R iv istu .l i Ne u ro rud iologio l 5: 333-356. 2002

Upright, Weight-B e aring,Dynamic-Kinetic MRI of the SpinepMRI/kMRI

J.R. JINKINS, J.S. DWORKIN*, C,A. GREEN*, J.N GREENHALGH'I, M. GIANNI+, M. GELBIEN*,R.B.WOLF*. J. DAMADIANX. R.V DAMADIAN*Medical C(llega of Pennsrlvania Hahnennun, Drexel Univercit"-, Philadelphia, Pennsylvania;* Fdnr ('orDorotion. l\Ialville. Neu,York

Key rrordsr magnetic resonance imaging spine. kinetic spine imaging. upright spine imaging. dyrramic spine imaging

SUMMARY - The purpose of this study was to demonstrate the general util ity of the first dedicatedmagnetic resonance imaging (MRI) unit enabling upright, weight-bearing positional evaluation of thespinal column (pMRI) during various dynamic-kinetic maneuvers (kMRI) in patients with degenerativeconditions of the soine.

This study coniisted of a prospective analysis of cervical and lumbar imaging examinations. All stud-ies were performed on a recently introduced whole body MRI system (Stand-Up"' MRI, Fonar Corp,Melville, NY). The system operates at 0.6T using an electromagnet with a horizontal field, transverse tothe longitudinal axis of the patient's body. Depending upon spinal level, all examinations were acquiredwith either a cervical or lumbar solenoidal radiofrequency receiver coil. This unit is configured with atop/front-open design. incorporating a patient-scanning table with tilt, translation and elevation functions.The unique motorized patient handling system developed for the scanner allows for vertical (upright,weight bearing) and horizontal (recumbent) positioning of all patients. The top/front-open constructionalso allows dynamic-kinetic flexion and extension maneuvers of the spine. Patterns of bony and soft tis-sue change occurring among recumbent (/MRI) and upright neutral positions (pMRI), and dynamic-ki-netic acquisitions (kMRI) were sought.

Depending on the specific underlying pathologic degenerative condition, significant alterations ob-served on pMRI and kMRI that were either more or less pronounced than on rMRI included: fluctuatinganterior and posterior disc herniations, hypermobile spinal instability, central spinal canal and spinalneural foramen stenosis and general sagittal spinal contour changes. No patient suffered from feelings ofclaustrophobia that resulted in termination of the examination.

In conclusion, the potential relative beneficial aspects of upright, weight-bearing (pMRI), dynamic-kinetic (kMRI) spinal imaging on this system over that of recumbent MRI (rMRI) include: the revelationof occult disease dependent on true axial Ioading, the unmasking of kinetic-dependent disease, and the a-bility to scan the patient in the position of clinically relevant signs and symptoms. This imaging unit alsodemonstrated low claustrophobic potential and yielded relatively high-resolution images with little mo-tion/chemical-shift artifact.

Ricevuto i l30.{)7.2002

333

Upright. WeightBearing, Drnani(Kitvtic MRI of the Spine LR. Jinkins

Introduction

Magnetic resonance imaging (MRI) using com-mercial systems has until the present been limitedto acquiring scans with patients in the recumbentposition. It is a logical observation that the humancondition is subject to the effects of gravity in po-sitions other than that of recumbencv'. In addi-t ion. i t is c lear lhat pal ients exper ienie s igns andsymptoms in dynamic maneuvers of the spinal col-umn other than the recumbent one. For this rea-son, a new fully open MRI unit was configured toallow upright, partially upright, as well as recum-bent imaging. This would at the same time enablepartial or full weight bearing and simultaneous ki-netic maneuvers of the patient's whole body orany body part. The obiective was to facilitateimaging of the body in any position of normalstress, across the limits of range of motion, and im-portantly in the specific position of the patient'sclinical syndrome. Under optimized conditions itwas hoped that a specific imaging abnormalitymight be linked with the specific position or ki-netic maneuver that reproduced the clinical syn-drome. In this way imaging findings could poten-tially be tied meaningfully to patient signs andsymptoms. Furthermore, it was anticipated that ra-diologically occult but possibly clinically relevantweight bearing and/or kinetic dependent diseasenot visible on the recumbent examination wouldbe unmasked by the positional-dynamic imagingtechnique: .

Material and Methods

This study consisted of a prospective analysis ofcervical and lumbar MRI examinations. All exami-nations were performed on a recently introducedfull body MRI system (Stand-Up rM MRI, FonarCorporation, Melville, NY) (figure 1). The systemoperates at 0.6T using an electromagnet with a hor-izontal field, transverse to the longitudinal axis ofthe patient's body.

Table I Patienl Positionins rehted variations of MRI

. Recumbent MRI: rMRI:Supine, recumbent imaging

. Positional MRI:2MRI:

lmaging in varying angular positionsof longitudinal axis of body

. I(inetic MRI: kMRI:

Imaging during dynamic-kinetic somaticmaneuvers (f lexion. extension, rotation.lateral bending)

Depending upon spinal level, all examinationswere acquired with either a cervical or lumbar so-lenoidal radiofrequency receiver coil. This MRI u-nit is configured with a top/front-open design, in-corporating a patient-scanning table with tilt,translation and elevation functions. The unioueMRI-compat ib le. motor ized pat ient handl ing sys-tem developed for the scanner allows vertical (up-right, weight bearing) and horizontal (recumbent)positioning of all patients. The top/front-open con-struction also allows dynamic-kinetic flexion andextension maneuvers of the spine.

Sagittal lumbar/cervical T1- (TR: 680, TE: 17,NEX: 3, ETL: 3) weighted fast spin echo imaging(Tl FSEWI), sagittal lumbar/cervical T2- (4000,140-160,2. 13-15) weighted fast spin echo imaging(T2FSEWI), axial lumbar Tl WI (600, 20, 2) orTl FSEWI (800, 17, 3, 3), axial cervical gradient re-called echo T2*-weighted (620-730, 22, 2)(T2*GREWI) were performed in all cervical/lum-bar studies, respectively. In all cases, recumbentneutral, upright neutral, upright flexion, and up-right extension imaging was performed. The pa-tients were seated for the upright cervical exami-nations and for the neutral upright lumbar acquisi-tions, and were placed in the standing position forthe lumbar kinetic studies.

Patterns of bony and soft tissue change occur-ring among recumbent neutral (rMRI) and up-right neutral positions (pMRI), and dynamic-ki-netic acquisitions (kMRI: upright flexion-exten-sion) were sought (table 1). Specifically, degenera-tive spinal disease including focal intervertebraldisc herniations, spinal stenosis involving the cen-tral spinal canal and spinal neural foramina, andhypermobile spinal instability were compared toother visibly normal segmental spinal levels a-mong the rMRI, the pMRI and kMRI acquisitions(tables 2-7).

Focal disc herniations were defined as localizedprotrusions of intervertebral disc material that en-compassed less that 25% of the total disc periph-ery in the axial plane; central spinal stenosis wasdefined as generalized narrowing of the centralspinal canal in the axial and/or sagittal plane rela-tive to that of other spinal levels; spinal neuralforamen narrowing was defined as general nar-rowing of the neural foramina as determined fromsagittal acquisitions relative to that of other seg-mental spinal levels; and hypermobile spinal insta-bility was defined as relative mobility between ad-jacent spinal segments as compared to other spinallevels that in turn demonstrated virtually no inter-

334

Riv isur di N euroratliologin 1 5: 333-356. 2tfr2

segmental motion. Generally speaking, degenera-tive disc disease was defined as both intrinsic dis-cal MRI signal loss as well as morphological alter-ation to include a reduction in suoeroinferior di-mensional disc space heigh t.

Alterations in sagittal spinal curvature werealso noted between the neutral rMRI and oMRIacquis i t ions ( tab le 8) . F inal ly . notat ion was madeas to whether or not the patient was referred inpart because of an inability to undergo a priorMRI due to subjective feelings of claustrophobiaattempted in a "closed" MRI unit.

Results

The neutral upright imaging studies (neutral-pMRI) demonstrated the assumption by the pa-tient of the true postural sagittal lumbar cervicalor lumbar lordotic spinal curvature existing in the

patient at the time of the MRI examination, a fea-ture that was partially or completely lost on theneutral recumbent examination (rMRI) (figures2,3). In other words, this relative postural sagittalspinal curvature correction phenomenon was man-ifested by a change from a straight or even re-versed lordotic curvature on rMRI to a more lor-dotic one on pMRI. Increasing severity of focalposterior disc herniation on the neutral-pMRlcompared to the rMRI was noted (figure 3), andwas yet worse in degree on extension-kMRl (fig-ure 2); these posterior disc herniations were lesssevere on flexion-kMRI maneuvers as comoaredto all other acquisitions (figure 4). Absoluie denovo appearance of disc herniation on neutral-pMRI was identified on extension-kMRI acquisi-tions in some cases as compared to rMRI (figure2). A reduction of intervertebral disc height wastypically noted at levels of disc degeneration (fig-

Table 4 Types of intersegmental spinal motion

. Eumobility: normal motion

. Hypermobility: increased motion in theX, Y, Z planes

. HvDomobilitv: decreased motion

Table 5 Positional lluclualion in spinal ligaments and discs(p/kMRI)

Li game ntotactic effects

Intact spinal ligamentous structures

- Contained bulging peripheral disc material

- Inclusion of disc material within discspace when ligaments are tensed

- Further protrusion of disc material intoperispinal space when ligaments are relaxed

Table 6 Dysfunclional intersegment.l molion (DlM)

. DIM is a form of intersegmental hypermobility

. DIM engenders generalized acceleratedintersegmental degeneration

. Mechanism of accelerated spinal degeneration:chronic. reDetitive autotrauma

Table 2 Dynamic spinal olterations

. Bony Structures:Intersegmental RelationshipsRange of MotionSpinal Contour

. lnteryertebral Discs:- Disc Height- Disc Margin

. Ligaments:Ligamentotactic Ef fectsLigamentopathic Effects

. Perispinal Muscles

. Neural Tissue:Spinal CordSpinal Nerye Roots(ventral and dorsal)

Cauda Equina

Table 3 "Telescoping" of spinal column in degenerative disease

. Intersegmenlal settling:- Disc collapse- Posterior spinal facet (zygapophyseal)

joint subluxation

. Annulus fibrosus redundancy

. Ligamentous redundancy

. Meningeal redundancy

. Neural redundancy

335

I p n q h r . \ \ t , i s l t r B n t t i t r q . I ) t t r r u t t t t K u t t t i \ l l l ! t ) l t l h . r ) t n r

. \ s

l /' I

I ; r ! L r r c I V i r r r o u . l ) l l l r r r r l l i r l r l r r L ' l i ! u r i i l r o n \ o l t h . S l l n d t I\ l R I u I i l : \ ) l ) i r l i . n 1 i n \ l r r L l i n ! f ( ) \ i l i o n ( . l i r n r l i g n ( . u l r i r l I ) \ l R l ) :1 J ) | r l i c n l i n ' r c L | | r h r n l t ) ( \ i l i ( ) n ( r \ l R I ) : ( ) l r i t l i r n r i r 1 r . n d . l t r h r r !

f r \ i l i 1 , n 1 l r r ! i L l r \ . i L n s l r i l p \ l l t 1 ) : 1 ) ) f r l L . n l I r r r f \ r c r l l l r \ r ( ' n r \ 1 r r l\ r ( i n n r r n . L r \ L j r \ 1 k \ l l t l ) : t : ) I r a l i r n l r n l u r n h r r l l r \ j o n . \ r e n \ r o n n r i i "n ! u \ ! r \ l k \ ! l t l ) : I ) l r i r l i r n l i n \ f r l . r l u p r i ! h l f ( i \ i l i r ) | ( \ . 1 1 ! d | . u l r i r lt , \ l l { I )

l t6

Riv ista di Neulo rudiolosia 15: 333-356. 200�2

Figure 2 Sagittal cervical spinal curvature correction: unmasking of central spinal stenosis; occult herniated intervertebral disc (all im-ages in same patient): A) recumbent midline sagittal T2-weighted fast spin echo MRI (iMRI) shows straightening and partial reversalof the sagittal spinal curvature of the cervical spine (double headed arrow). Minor posterior disc bulges/protrusions are present at mul-tiple levels, but the spinal cord (asterisk) is not compressed. B) Upright-neutral midline sagittal T2-weighted fast spin echo MRI(pMRI) shows partial resioration of the true sagittal postural cervical curvature upon neutral-upright positioning (curved line). Notethe relative increase in the posterior disc protrusion at the C5-6level (arrowhead) and encroachmeot on the spinalcord (aste sk) ascompared to the recumbent image (A). C) Recumbent axial T2*-weighted gradient recalled echo MRI (rMRI) through the C4-5 levelshows patent neural foramina bilaterally (single headed arrows), and mild stenosis of the central spinal canal (double headed arrow).C) Upright-neutral axial T2*-weighted gradient recalled echo MRI (pMRI) through the C4-5 level shows bilateral narrowing of theneural foramina (single headed arrows). Note also the narowing of the central spinal canal (double-headed arrows) relative to the re-cumbent study (D), and the compression of the underlying spinal cord [i.e., relative anteroposterior flattening of the spinal cord ascompared to the recumbent image (D)].

337

Up rillht, Weight- B?arint!, D|D(Dtit-Kineti( lr,lRI of thc Spi r

ures 3.4). Increasing severitv of central spinalcanal stenosis was identified on neutral-oMRI andon cxtcnsion-kMRI acquis i l ions. as comparcd torMRI, and was overall ntost severe on extensionand least severe on flexion-kMRI acquisitions (fig-ures 2.5). Similarly. increasing scveritv of spinalneural foramcn stenosis was identified on neutral-pMRl (figures 3). as compared to rMRI. and wasoverall most scvere on extcnsion and lcast severeon flexion-kMRl acquisitions (figure 6). Increas-ing central spinal canal narrowing with spinal cordcompression on extcnsion-kMRI was identificd insome cervical examinations (figure 2) as comparedto recumbent IMRI. neutral-pMRI and f'lexion-kMRI maneuvers. T ianslat ional sas i t ta l o lane in-lcrsegmcnta l hypermobi l i ty wa, idcnt i f icd ar somclevels associated with degenerativc disk discaseand minor anterolisthesis of a dcqenerativc nature

33u

(figurcs 5.7). Postoperative spinal stability was i-dentitied across levels of prior surgical fusion (fig-ure 8). No examination was uninterpretable basedon paticnt motion during anv portion of the MRIacquisitions. No patient was unable to completcthe cnt i re examinat ion due to subject ive lee l ingsof claustrophobia.

Discussion

Convent ional recumbent MRI. or rMRI. is obvi -ously inadequate theoreticallv tbr a completc andthorough evaluation of the spinal column and itscontents. The biomechanics ol human conditionincludes both wcight bearing body positioning. or/ ) M R l . a s u c l l a s c o m p l e x k i n c t i c m a n e u r e r s . o rkMRI in threc d imensions ' " . The present MRI u-nit was intended to addrcss these considerations.

Figure: E)Uprighl cxtension nl idl inc sa-qi l tal T2-wciShtcd f |sl \pin echo l \ ,1Rl (exrcnsion kMRI) sh() lrs furthcr poslerior pfolrusionol the inlervcrtcbral discs at mult iple levels (arrows) and anlerior inlbldinq ol lhc poslcrior \pinal l i lLamenls (ar;()whcldsj. r .esult ingin overal l worsening of lhc stcnosis ol the ccntral spinal canal. Nole thc imtingemcnl ( i .e.. compressidn) of the untlerlving spinal corl(asleJr.5kJ_bv lhcsc cncroaching spinal sol l l issue elcmcnls. F') Recumbcnl a\ i i l lT2: ' rciehred gr.adient r.ecal lcd ccho MRI i fMRI) allhc C5 C6 disc level shows poslerior paradiscal osleophve l i)rmnlion (arrowhcad) exte-nding into thc xnlerior aspecl of the ccntralspinl l_canal. Nolc thal the ceNical spinal cord is alrophic. hut lherc is a r inl ol CSF hvpcrintcnsit ! enl irelv surrounding lhe cord. C)Uprighl cxtcnsion axialT2: ' rcighted gradienl recal led echo MRI (exlension kMRI) rereal inq lexicnsion,iel l ted) tbcal Dosteri)r cl ischernial ion (arrow). Nole thc o\eral l increased rtenosis ol lhe ccnlral spint l canal .rn.t the c,,rrrfrrr ' \ \r , ,n-tndcnrrr i , 'n 0l lhe underlyingcervical soinal cord (aslerisk ).

TT

r r ( \ l l i k r l \ t \ . t l l r \ r \ S L ' | r r f r l r r r r c ( ' l r . r d r I t r r ] | t ' l r r r l J \ r h r L l ! f r r - , r r . , \ L l n , r L , r l r i l r u l . 1 { i 1 h r \ l r h r r r ( ) r ) r . l l , ' r l

.i.19

Upright, Weight- Bearing. Dvnunic-Kinetic MRI oJ the Spint J.R. Jinkins

ilP,:f"l.-1] l:::l?:ll]:l!lii"- l,ltg'lcfr,"1 T1-weishted ^fast spin echo MRt (rMRI) on the parient s lerr side shows narowins or rheL)/r I splnal neural Ioramen (dashed arrow).as a.result of posterior disc protrusion, interveriebral disc space narrowing and iaradis-cal o' leoFhvtc lurmation- F) Uprighl-neulral midl in( parn;acitral I I .weighred fasr splp ..1lo vnripMft i i"" ' r i" "ui i .n, . t" ' r , , . t .:"^::r . i . . .T,I l- . ] .ry1:l l ' r /ed

narro$rng ol,al l ol rhs \pjnal ncurat forJmina tsotid arro\as). inctudrnp thtr L5rS I tevet tda.f ied arrolr) (com_pare wllh.recumDent examlni l t lon. t) Al-some point in this stenol ic process. the exi l ing neurovascular bundle (asterisk) wi l l undcrgocompression and may become svmptomatic.

Both occult weight bearing disease (e.g., focal in-tervertebral disc herniations, spinal stenosis, thecalsac volumetric change), and kinetic dependent dis-ease (e.g.. disc herniations. spinal stenosis. hyper-mobile instability) of a degenerative nature 7rrwere unmasked by the p/kMRI technique. In addi-tlon, a true assessment of the patient's sagittal pos-tural spinal lordotic curvature was possible onneutra l upr ight pMRI. rhereby enabl ing berrer e-valuation of whether the loss of curvature was dueto patient positioning (i.e., rMRI) or as a probableresul t o f somat ic per isp inal muscular gurrd ing orspasm (figures 2,3). Axial loading and dvnamicflexion-exlen5ion studies by othir reseirchershave borne these varied observations out:{rt.

Simple upright or upright pMRI, showed a phe-nomenon here lermed " te lescoping" whereby thelevels of generalized intersegmental spinal degen-eration showed a collapse of the spine into iiself(figure 4) ".

Consequent redundancy of the discal, ligamen-tous and meningeal tissues of the spine resulted in

340

increased degrees of central canal and lateral re-cess spinal stenosis, while craniocaudal shorteninsof the spine associated r . r i th te lescoping caused in-creased degrees of neural foramen stenosis (figure3) . On occasion. the degree of f rank poster ior t ischern iat ion was seen to enlarge wi th upr ight pMRI( l igure 3) . This lar ter f ind ine would seem Lo be animportant observation, obviously improving thequalitative nature of the analysis in relevant casesof disc herniation. Finally. upright-neutral imagingfrequently showed increasing degrees of sagittalplane anterolisthesis, both in degenerative spondy-lolisthesis and in some cases of soondvlolvticspondylo l is t hes is

Upright extension kMRI tended to showgreater degrees of central canal and neural fora-rnen stenosis, while flexion kMRI revealed a less-ening or complete resolution of the same centralcanal and neural foramen narrowing (figures 5.6).These phenomena were only observed at levels ofdisc degeneration (i.e., both disc desiccation anddisc space narrowing) ' ' '.. In exceptional cases, de

L'pi i(ht. l4'd!:ht- B( ri !1, D\'tluttliL Ki t,ti( lllRI t)l th( Spint:

/l(/v(, posterior disc herniations wcrc revealed onlvon upright-extension kMRI (figure 2). When pre-scnt in the cervical spine. such cases invariablvshowed compression of the undcrlying spinal cord.Overall. this was fclt to be one ol the most impor-tant observations noted in this study. lnterestinglv.some of the posterior disc herniations became lesssevere whe n upright flexion kMRI was performcd(figurc 4).

This would seem to bc worthy of preoperativenote to thosc surgeons that operate on the spinc inpositions of llexion. Presumably this phcnomenonis caused lx a liganrcntotuctic effact: the intactflbers ol the anterior and posterior longitudinalligaments and the intact peripheral annular fibcrshave effects upon the underlying disc material. al-ternatelv allowing morc disc protrusion when lax.and lcss protrusion when taught. It was notcd thatall cases of fluctuating intervcrlcbral disc hernia-tion had MRI signal loss compatible with desicca-tion as well as intervertebral disc space height rc-duction "".

342

Thesc disc findings wcrc also invariably true incascs of sagittal ("x") plane hypermobile spinal in-s tabi l i ty r " ' . I t was possib le to judge even minordegrees of translational hypermobile spinal insta-bility (e.g.. mobile antero- or retrolisthesis) grosslyas well as by using direct region of intcrcst mca-surements (figures 5.7). The kMRI technique obvi-ouslv does not suffer from the effects of magnifi-cation and patient positioning crrors potentiallyinhcrcnt in conventional radiographic dynamicflexion-extension studies traditionally uscd inthese circumstances. Thcsc instances of interseg-menta l hypcrmobi l i tv sccm in par t to be a mani-festation of spinal liguntentoputhv'". As the prin-c ipal ro les of sp inal l igaments are to s tabi l izc thcsegments of the spine and also to limit the range ofmotion that the spinal segments can traverse. de-generative stretching or frank rupture of these lig-amcnts will predictably allow some degree of in-tersegmental h)'permobilitv'" "r.

Other alterations in the intervcrtcbral discs andposterior spinal facet joints will have either posi-

Figurc 5 Worscnine-reducing ccnlral \pinal canal slcnosis on d!nrmic-kinetic MRI (kMRI): minor lranslat ional inlcrscgmcntal hv,pcrnrobi lc instabi l i tv on dvnamic-kinct ic M R | ( k M R I ) A ) Rrcu r ir hc rr L m r. l l inc 'agi l tal T2-weighlcd lasl sl i11 echo M R I ( r i , l RI ) showsmild. general ired spondvlosis and minor gcncral ircd narr()$inq ol lhe centr i l l spinal canal. B) t-rprighl ncutral midl ine sxgit lal

'12-

\\ 'eightcd fast spin ccho MRI (pMRI) sh()ws vcrv nl inor \vorsenine of lhc ccntral spinal canal stcnosis inleriorlv (+) relaltve to the rccrmbenl i age (A). Nolc lhc assumplion by lhe pLl l icnt ol lhc lruc poslural sagi l tal lordol ic curvi l lurc of the lumbosacral spine rscomparcd lo the rccumbcnl cxrminal ion.

Rivistu I i Net!f t)ruI i t lognr 15: 3.3.3-356.2002

Figure 5 C) U priSht-exlension midl inc sagittal - f2

wcighled Ias( spin ccho MR | (kMRI)rcvcalssevereworseningofthecenlrt lspinalcana l s tenos i s i n t he l owe r l umbar a rea (a r rows : L ' l - L5 .L5S l ) .Th i s resu l l s f r omacomb in { l i ono f f ac lo r s . i nc l ud i ; e redundancvo f t heIheca l sac andsp ina l l i gamcn l s and i nc reas i ru pos te r i o r p ro l f us ions o f t hc i n te r \ c r t . b r i l l d i \ c \ . r t L l - i i | nL iL5S l .D )Up r i gh t - f l ex i onmidl ine sag.i l lal f2-weighted f i tst spin ccho MRI (kMRI) demonstrates complete reducl ion of lhc posrcrior disc protrusi iniar the L. l-5 and L5_Sl lcvels. lnd resolut ion of the ccnlral spinal canal slcnosis a1 thcse lurnbar scqnrcnts (c;parc with Cj. Also note that thereis nl inor anierol islhesis at Ihe L2-3 and L:l 5 levels as compared to the neutral cxaminal i()ns (A.B). indicating rssociatcd mild transla-t ional interscqmcnlal hypertnobi le instabi l i ty al thcsc Icvels.

tive (i.e.. hypermobility) or negative (i.e.. hypomo-bility) effects upon intersegmental motion ̂ . o..

Also noted at levels of disc degeneration was asagittal plane hypermobile "rocking" of the verte-brae in relationship to each other (figurcs 4.6),'".Observation of the opposed adjacent vertebralendplates in such cases showed them to move inrelationship to each other to a much greatcr de-

'l'able 7 Translational hvpelmobile instabilit.l of the spinal cot-

L i ga nte n t o p a t h i c alter ations'.l igamentous stretching/rupture

Mobile translational antero- and retrolisthesis(X-plane )

- Mobilc latero- and roblisthesis (Z and Y-planes)

Dynamic overextension of spinal range(s)of motion(X. Y. Z planes)

Tablc tl Tvpes of upright postural spinal curvature

. Normal curvatureCervical: lordotic

- l horacic: kyphotic- Lumbar: lordotic

Exaggerated curvature- Hvperlordosis- Hyperkyphosis

. Loss of sagittal spinal curvature(straight spine)

- Hl,polordosis- Hvpokvphosis

. Coronal plane scoliosis(direction of convex curve)

- Leftward: levoscoliosis- Rightward: dextroscoliosis- Serpentine: serpentine scoliosis

343

Upright.W(ight Bcurit tg, Drnontic Kitk|. t i ( MRI ol t l l . ,spit tr

F i gu re 6 E f t ec l so fd tnan l i c k i nc l i cnancu \c r s ( kMRl )onsp inn l ncu ra l i ) ( r n r i n i r a t l c vc l s o f dcqcne [ r t cd t l i s c t l i s c . r sc i l nd t hco rc t i -ca l ] i ga .men lous . l ax i I v ( i ' e ' . I i gamcn top l1h t ' ) : ' d vs func1 i01a l i n1c rs tgmcn l l | ]mo l i r ' nA )Rccun rben1p l r1 t s l l g i l t a lT � � l lN � � � � � � � � � � � � � �cho MRI (rMRI) \hows intcNerrcbral disc deqcncral ion l l l lbc LS-Sl levcl (rsrcrisk). N(ne thc i l l nariorvinq of thi-neural foramcn(n r ro \ \ ' ) a t1h i s l evc ] ( i - e ' 'm ioo r t ) r am ina l \ l en (x i ' . - and thcnc | rpa r i l | c l su . acc \o l l bcvc r1cb ra Iend � � � � � � � � � � � � � � � � � � � � � � � � � � � � �

j : l . . i l " .P"i l ' :Cl! l l I l :

$ cighttd frst rp11 4.1,u MRI (k MRI ) re\eals furlhcr nrrrowin{ of rhc neurat rul^ni.n l i i i i l i r i" t tuo r r"r"-l t \ c r , , r h< r ( cumhr l | t rmJs r / \ ) . \ . , t , . t h ( upcn in r , , t t hL . I r t c r r r , r , , \ l ( ( r . , r r h , . . l r . i . l : r r e r J , , uh lu hc : r J r . L i . r r r , , $ r . ( 1 , , \ r np , , r l h ( pu .

l " , " j l ' , ; l T ; l ] i . 1 l . . 1 , ] . i : j ] : ] ) . : l " : . . ] ' . ' ] . " ' : . ' l o t hc recumbcn1 ina8c (A ) . ( . ) t : p r i g | r l - l l c x i ( ) n l l r asae i l 1a l ' I . 2 .wc igh � � � � � F � � � � � � � � � � �) l I :" ! l ' : '11,)

ucmun\lrrte\ , 'p!nrns , ' � l thc neural forrnren al L5-sl (rrro$). lhc openin1] ot 'rhe posrorior aspeit of the disc spacej l : l , " : . j : ] ] y : y ' : ' , I : , : l ' ) . c - | oS |n ! ' . , l , t hc i | n te r i o r l spec to l l hdd i \ cs � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �( l lne\ l t lgure\ t l . L l l lu\ l l i r l , r Ll\ ' \ i n(ttr ,nal inlcrsegmenlal moti()n in rddit ion to thc dvnamic chan{es in thc sizc ol lhc neural rora-n rcn r1 ' l e !e ]So ld i scdcgcnc I i I l i onand lbeo rc t i c i l | l i g : | n ]en tous | l \ i l \ ' ( i ' c ' . l i g i lmen1oP � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �somcwhal enlafqed t\ c(nlpared t() lhc recumbcnt irnd the c\ lensi(r; inlue\lA.B).

relr(Jl l rPrn1(nlrru\ lr \r l \ ( I i r" l rP,irn!ntoPit lht ) A) Reclmbcnt midl ine sa!ir tal T l-ncightcd i lsl spin ccho NIRI (rMRI) snows nrnor.lc\\ , lnirn qrruc l . .rnlcrr"r \p' tr l t l \ l t ' � l l \ lhests l l the L1-5 level ( lrrowhcad). lhe pars interart icul i i r is was inlact on hoih siclcs l t rhisl < \ c l . \ , ' l c t h ( r c l i l L l o n s h l O h e l r \ c u I l h elevel Nole-the rel. l l ionship helwcen lhe anlerior surluces ol the L-l und L-s vertcbfal b(rdies iclashcd l incsl. Bl Upriqhi,neutrat mid,l ine sagittal r I 'wciShrcd i .st spin echo M R,l ( FM Rl ) rrr eirts nr in, ' r r \ ,)r \unrn{ . t r l ,e anr.t i , , . r i i f . i i i l , ; ; i : i i l l^; l i ; j ' ; ; ; . , ," l . , , . " , , ,npa rcd l o l he r ccumben t dxan t iDa l i on . C ) L p r i qh t - l l c r r , , n m iJ l t r \ . r u I l T l - \ \E iqb t cc l i as l sp incchoUn t l tVn t i aen tons t ru r cs tu . -1he ran tc r i o r5ub ]ux : r1 i ono lL - l r l n I , 5 i n | | c \ I ( ' n (L l l shcdJ r r . l u ) . . r s t . r n r0 l r r ed to . l i gu |esA .E | . ' I h i sdcn l t l ns l i a l c i l 1 � � � � � � � � � � � � � � � � �

I n e | < | J I | n n \ h l f h C l \ \ i ' \ ' n l l l ( i | | ) l ( ' | l , n . u r l ' | ( . ' . , , l l l l f I | . l l l L l I i ! ( l t ( h r : | | h , r J r c . l L l ' r s h t J � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �recumbenl i lnacc (A).

344

R i I i stu I i N eu tu ) tul iolr,qi( I 5r -.133-356. 2(X)2

Figure lJ Postoperalive inlerseqmental fusi()n stability (four )ears status-post clinicallv successlul interbody bone grall lusion). A) Up-riqht ncutral midl inc sagittal Tl wcightcd fast spin echo MRI (pMRI) shows the surgical iusion at C5-C6 (asterisk): autologous bonydowels \vere used ibr thc oriSinal fusion perlbrmed,l vcars prior to the current examinal ion. Notc thc normal bony iniersegmental ver-tebral al isnmcnt and normal upright postural sagi l tal Iordotic curvalure. B) Lipright-neutral midl ine sagit lal T2-weighted tasl spin echoMRI (pMRI) aSain shows thc interscgmcntal fusion (asterisk). Note the good spatial dimensions ofthe CSF surrounding the spinal cord.C) Uprighl-nexion (arro* ) midl ine saSi[a] T2-weighted fast spin ccho MRI (kMRI) shows no intcrsegmenral sl ippase ar. suprrjacenrto. or subjaccnt to thc surgical lv fuscd lcvel (sol id l ine). Note the maintenance oi the anleroposterjor dimension of the central spinalcanal. D) Uprighl-extension (arrow) midl ine sagi l talT2 weighted fasr spin ccho MRI (kMRI) again revcals no inlerseqmenlal hyper,mobilc instabi l i ty ( i .c.. no intcrscgmental mobil i t) , : sol id l ine) or cenlral spinal canal compromise a1 any level.

gree than is observed at levels with normal inter-vertebral discs as judged by MRI (figures 4.6). Thisis herc termed as tlvs.funttionul inter:iegmental no-/ ldr (DIM).

The significance of DIM is the theoretical possi-bility that such pathologic vertebral motion mavengender gencralized accelerated intersegmental

degeneration due to the effects of micro-auto-trauma over long periods of time. The self-protect-ing spinal mechanisms inherent in the normal in-tervertebral discs and intact spinal ligaments arelack ing in such cases. perhaps in i t ia t ing a progres-sive degenerative cascade of degeneraldjve outotra-ntati zi ng hy permobil it1t.

-t4)

Upright, WeighbBeatin+, Dynanic-Kinetic MRI ofthe Spine

Table g Combincd effects ofspinal degenerrtion with telescoD.ing. diskopaahy. ligrmentopalht hypermobite iltstobitity. & Dli4

Table 10 Clinicoradiologic relevrnce ofpl&MRI

l]9::: :- j,.:l:p:1"-'11: intersegmental-hypermobile instability al segmenr above fusion.5 years fo owing bitaleral fusion (pedictescrews.and rods extenchng belween L4-Sl ) and bi laleral lamineclomy at the Lzt-Sl levets A) Recumbent mibl ine sagit tal T I -w;ightedfast sPin echo.MRI (rMRl) shows bilateral lamineclomy extending-from L,l--S I (arrowheais). The patient aiio haf 6il"teral pjdicl.screws and rods extendlS-from and to lhe same Ievels { not shown ): No melallic arlifact is present Ue'cau=. rtre suieiirl ;atenals werecomposed of l i tanium.-B)sagirtal-uprighl-siuing ( i .e.. parr ial f lexionr midrineT2-weighred t ist spin echo MRI (p,,t 'MEi joemonstratesmarxeo antenor sllp ot lhe LJ vertebral body upon the L4 verlebra (dashed arrows). Also note the resullant mari<ed stenosis of the cen-tral sPinal canalat the-L3-4 level (solid arrow), and resultant encroachment of the-bony structures of the spine upon itre cauoa equlna(courtesy of M. Rose. M.D).

J.R.linkins

. Spinal Stenosis [central spinal canal, lateral

recesses (subarticular zone), neural foramina]

. Spinal Cord/Nerve Compression

. Somatic Nerve Endins Irritation

. Neuromuscular/Ligamentous Autotrauma

. Related Patient Signs/Symptoms

. Patient care considerations

- Improvement of imaging sensitivityover that of recumbent examinations

. Medicolegal aspects

- Revelation of diagnoses missed

on recumbent examinations

. Worker's compensation

- Revelation of occult pathology not foundon recumbent examinations

. Economic factors

346

bl.-,.

f r r \ \ ( l l r r l , , 1 l l r r r I i ! l u r r l r l i . . h r f l r L r r r o r r r ( L ' ! r l ! \ \ t i l \ l l i , \ . \ l I ) )

l l t \ ! \ t t t t l i \ t I t , ) n k l i , r r , ! / , / l 5 l r l l 5 h . l l r l ) l

1i

.r+7

I J n g h t . \ \ i i q h r l l t \ u u t { . l ) \ ' t r t t n t t t K i t t t t i L \ ! l l t o j r t t t . \ t t t t t t

\ l R l ( k \ l l t 1 ) r ! i r n \ h r ) \ \ \ l h r n ( i n r r i r l l ! l r l l : r r r r r r l I ' c n r l i n r : i r | l ] ! r J i r n ( r , ) t l h . 1 1 ] i n . r t . , , l L r r r r r L

l.+8

t ,

\

;t

Rivista di Neuroral iulogia l5: 333.350.2002

I9",::] l "T::. l i ]:-p-f y,l l ; :! l l l* l^*:" of - Lhermine \ Svndroms . or ctecrrical !ensarions exrcndrng do\r n horh upper exlremr-j]:: :ry:, '1.1.'_:l : l

rne cervrcal.sprne A) Recumb(nr midline sagittal T2-weighred spin echo MRI { rMRa shows rhe noimat appear-ance.or tne ccrv lcal \p lnal cord (b lack dstcr lsk) dnd lhe l \ ro lerel poqrer ior d isc prutrusionq al the C5 Co and C6-C7 lcrels (wl . i i i ( as-

l .^: ' :\ ' . ]:^B"lYt:ql '.::"l lr l T9].: \agrrral T2-wcrshred..!prn echo MRt rkMirr demonsrrares anrerior dispraccmenr of rhc spin.rl

::;:'''ii'i'ifJfiil*fft "ililF:fii:':Jil"lL'"1:Ti:;l"lTJ::l,"Ji,jii,:li!"y5l5l#:!::"Ti:i'1"_:1-+li,;1;:;l*fftllli i(5red symptums conri: 'renr wirh Lhcrmirre . slndromc during this ftexion "iuoy.Tri" "i"d'y ;;;. r;; ;; i ;; i ,; i ;;; i ;; i , ' . . nn,ur. o,dynamic-kinetic MRI (kMRI) in its ability to correlate a speciific imaging acquiiition wih i sp*iiic crii,lc"L.i;;j;;*'

Figure l4-F,at suppression (STIR: short tau inversion recovery) lechnique.A) Recumbenr midline sagrrral Tl-weighled iast sprn echoMRI (rMRI) shows normal vertebral marow. epidural and perivertebial fat' (asle risks). B) n.."-u!"i .iolir" ,""giilirz-i,.igl,,"al:;:,.oJ,i:.1:Yl,,, lyl l l_l i l

'gl: i l fp*qsion rsrtR) showq excelenr rar supp,e.*ion eq,"riy a"r.-; 'r i;;;"i;; l ;;;; rtarge isrcr_lsKs, L\ole lne gooo \lsuallTalton ol lhe conus medulari< (small aslerisk) and the n(rve roots ofthe cauda equina 1arr5ws1.

349

Uprillht, Weight-Beuring, DvnanticKinetic M RI rr.f the Spi ?

Figure 15 Ultra-fast imaging techniques for appl icai ion with spinal stress maneuvers:kMRL A) Uprighr-f lexion (arrow) midl inc sagittalT2-weighted driven-equil ibr ium MRI (kMRI) demonstrates normal spinal column mobil i ty. B) Upright-cxtension (arrow) midl inesagittal T2-weighted driven-equil ibr ium MRI (kMRI) again shows normal spinal column mobil i t l r . Nole thal there is some Increase rnthe posterior disc protrusions at mult iple levels. increased intblding of the posterior spinal l igamcntous struclurcs. and consonant minor. noncompressive nanowing of the anteroposterior dimcnsion of the spinal canal. These single-sl ice. driven-equil ibr ium imageswcre each acquired in thirty-four seconds (t ime: l7 sec x 2 NEX = 34 sec).This techniquc wil l l ikcly provc to be important in cases ofcri t ical stenosis of the central spinal canal undcr condit ions of hvpermobile inslabi l i tv. where the spinal cord may be in danger of com-pression during stress maneuvers-The d ven equil ibr ium sequences should al low verv brief imaginS acquisit ions and cnablc dynamickinetic patient posit ions to be sa[ely assumed fbr ver! short pcriods of t imc required by this technique.

Figure 16 Telescoping ol the spinal column associatcd with dcgcnerative disc disease. A) Diagram of recumbent spine showing de-generativc disc diseasc at thc L4 L5 lcvel. and degeneral ion ol the interspinous l igamcnt at this same lcvcl (scrraled l ines). Notc thcbulging ol the degenerated intervertebral disc al L, l L5 rcsult ing in mild narrowing of the central spinal canal (double headed arrow).B) Diagram of Ihe uprighl-neulral lumbosacral spine demonstrat ing gravity related ( large sol id arrow) narrowing of the l-4-t-5 inter-vertebral disc space (dashed arrow) and intcrspinous space (small sol id arrow) as compared to the recumbent imagc A. togcthcr withredundancy of th€ soft t issues bordering upon the central spinal canal. This telescoping of thc spinal column mav result in varying de,grees oI worsening slenosis of the centra] spinal canal (doublc hcaded arrow).

350

R ir ista di Neu rctudiolo gia 15l. 333-356. 2OO2

Ftgorc 17 .Li8(nenkrtadic a d liSanenbparri. cffects. A) Diagram of the recumbenl spine sho\ring degeneration of the L4-L-5 inter-!ertchral Ji \c.and inter\prnous l igament (serrated l ines). Note ihe mild peripheral bulging of the iniervirtebral disc at L4-L5. and themrnor narro\r Ing () l the ccntral \pinal cirnal (double headed arrow). Also note the near-pa;l let posit ion of the intervertebral end plateson eithcr 5iJ( of the L4-5 JIsc. B) Diagram of the upright-f lexed (sol id curved arrow) iumbosicral spine shows an increase in the an-lerlor dlsc protrul lon- (ofen curved rrrow) related to laxity of the anterior longitudinal l igament and anterior f ibers of the annulus f i-bro\u\. l ( \enlnP ol

, lhc poslcrior dr\c prolrusir,n bulge cau.e.i hy rcnsion rrf thi posterioi longitudinal l igamenl and rrmaintng intacl

fro\ l(rror lrher\ ol the annulus f ihrosu\ sl laying ol Ihe \pinou5 procc\\cs t5ol id straitsht arrowst. hypcrcipansion ol the inter\pinou\tpacc {\ l ippl lng,. opening up uf lhe po\t(r ior aspect ol the disc space (aqteri . l . , lashe'd curv(d arro;s). and narrowinq ol tnr anrenoraqp(ct ol thc d,\c space (straight dashed arrows). Nole.that the central spinal canal becomes wider (double headed arr<iw) as comparedlo the neutral posit ion or extension maneuver (A.C). AIso note thal the opposed vertebral endplates on either sidc of the degenJratedL4-5 inlcrvertebral disc assume an anleriorly directed wedgc-configuration (dysfunctional intirsegmental motion: C). C) Diagram ofihe uprighl-extended.lumbosacral spinc shows.an increase in thc posterior disc protrusion (open sriaight arrow) relat;d t; laxit:y of theposlcrior longitudinal ligament and anterior fibers of th€ annului fibrosus. lessening of the ;nterior ;isc protrusion caused bv tensionol thr anlerior lon8i ludinal l igament and remcrning intacl anlerior l iber\ of the a-nnulus l ihrosus. tol lrsion of thc spinous processes(.ol id stratghl arrows,r. opcntng up ot th( anrcrior disc space la!tcnsk. dcshed \ lralghl arrow. ). and narrowing of the'poster ior a.peclot thc dl lc.sprce.(da\hed cur\,ed arrows). Note thal the central spinal canal becomc.s narrower (double headeA arrow)'as courparcu rothe neutral position or flexion maneuver (A.B). Also note thal the opposed vertebral endplates on either side of the degenerated L4-5 interyertebral disc assume_ a posteriorly directed wcdge cr:nfiguralion. This lattcr observition indicates dysfunctional i;tersegmentalmotion at this level of disc degeneration. a resuh in pa of inle;segmental ligamentopathy (i.e.. ligamentois laxity/rupture).

-

B c

Provocative p/kMRI is an experimental tech-nique that may be of major practical relevance inthe future. By comparing images where the patientis pain or symptom free, with a specific position inwhich the patient experiences pain or symptom(s),the imaging specialist may be able to clearly linkthe medical images with the clinical syndrome. Inthis manner, provocative p/kMRI may become atruly specific diagnostic imaging method in casesof spinal disease (figure 11).

The images of the cervical and lumbar spine suf-tered very little from motion artifacts from eitherCSF or body origin; no study was degraded to thepoint of being uninterpretable. Patient motion wasnot a problem, this being overcome by simplyplacing the scan table at 5 degrees posterior tiltenabling the patient to passively rest against thetable during the MRI acquisitions. In addition, it

The postoperative spine may perhaps be bestanalyzed by p/kMRI in those patients who haveundergone surgical intersegmental fusion proce-dureso'. In the absence of ferromaenetic fusion im-plants. the MRI uni t was capable of ident ica l eval -uation as compared to the preoperative spine.Cases of stabile intersegmental fusion, for exam-ple, showed no evidence of intersegmental motion,thereby confirming postoperative intersegmentalstability (figure 8). Overall mobility of the spinemay also be negatively impacted by discectomyalone. unaccompanied by surgical bony fusion 7,,.

Spinal cord motion is another dynamic factorthat may be amenable to analysis in cases wherethere is clinically suspected congenital or postop-erative spinal cord, tethering.In test cases, for ex-ample, the conus medullaris was seen to freelymove anteriorly and posteriorly on flexion and ex-tension kMRI, respectively (figure 10).

351

Upright, Weight- Beuring, Dvnumic-Kinetic MRI ol the Spine J.R. Jinkins

A

Figure l13 Effects of weight bearing-neutral posture (uprighFneutral gravity and muscular balance effects). and dynamic-kinetic maneuvets on the neural foramina; dvsfunctional intersegmental motion (DIM) at levels of disc degeneration. A) Diagram of the re-cumbent spine showing degeneration of the L4-L5 intervertebral disc (serrated l ines)- Note the minor narrowing of the neural fora,men at this level (open arrowhead).The inlerior recess of the ncural foramen remarns open (rol id arrowhead). Also nole the near par-allel position of the intervertebral end plates on either side of the L4-L5 disc. B) Diagram of the upright-neutral spine (large solid s,lraight arrow: standing postural axial loading) showing degeneration of the L4-L5 intervertebral disc (serrated lines)- Note the minorincrease in narrowing of the neural fbramen at this level (open arrowhead: compare with A). The inferior recess of the neural fora-men is fu her nafiowed (solid arrowhead) by the increasing protrusion of ihe posterolateral aspect of the intervertebral disc (dashedarrow: compar€ with A). Also note the minor reduction in superoinferior height of the bony margins of the neural foramen, in part asa result of the disc space narrowing (dashed arow) associated with subluxation of the spinal facet joint arlicular processes (small s-traisht sol id arrows).

was found to be unnecessary to stand the patientfor upright p/kMRI of the cervical and thoracicspines; at present, only one sagittal sequence is feltto be necessary for evaluation of the lumbar spine,in order to analyze the lumbosacral spine for truepostural curvature and for considering issues ofspinal balanceltT!.

The remainder of the lumbosacral spine p/kMRI examination may be performed in the sittingposition.

The chemical shift artifact was minor on all im-ages, this being directly related to field strengthtthis effect would be expected to be less than one-half that experienced at 1.5 T. In addition, the de-gree of motion artifact from such sources as theheart or CSF motion was typically minor, evenwithout'flow compensation'overlay techniques

352

that were not used: this source of artifacts is alsorelated to field strength, commonly being worseon high-field MRI units.

Other currently relevant overlay techniques arepossible on this p/kMRI unit. Included amongthese are fat suppression imaging (STIR: short tauinversion recovery) coupled with fast spin echo ac-quisitions (figure 12). This is felt to be very usefulin the evaluation of spinal inflammation andspinal neoplasia.

Finally, in the patient with a possible criticalstenosis of the spine in association with hypermo-bile instability or positional worsening of the nar-rowing of the central spinal canal, long time periodacquisition sequences are of concern in the patientwho may have greater degrees of spinal cord orcauda equina compression in upright flexion-ex-

Rivista di NeurcrudioloSid 15: 333-356. 2002

\J

(

Figure l l t .C) Diagram of the upright-extended (curved sol id arrow) lumbosacral spine sho\rs. an increase in the posterior disc pro,trusion/bulge. and nalrowing of the posterior aspcct of the disc space (straight dashed arrows). Noie the increasing posterior disc pro-Irusion associated with obliteralion of the inferior recess (solid arrowhead) and superior recess (open arrowheadj of the neural fora-men (sol id arrowhead). the opening up of the anlcrior disc space (asterisk. dashed curvcd arrows). the narrowing of the postsrior irs-pecl of lhc disc space (straight dashed arrows). thc part ial shearing contracting subluxation of the posterior spini l facet lzygapopnv-scal). ioint processes (sol id slraight arrows). and the diminul ion in size of the antcriorlv bulging di ic (opcn curved arrow)."Ati" i roi"that thc opposed v-ertebral endplates on either side of the degenerated L4-5 intervertebral disc assurne a posteriorly direcled wed€leconfiguration (dYsfunctional intersegmenlal motion: C). D) Diagram of the upright- l lexed (sol id curvcd arrow) lumbosacral spinedemonstral ing anlerior disc protrusion (open curved arrow) relatcd to Iaxit), ol the anlcrior longi ludinal l igament. lessening of theposlerior disc protrusion/bulge as a r€sult of Iension of the remaining intacl posterior annular fib;rs. opening up of the pt,stJrior aspect_of thc disc sPace (asterisk. straighl dashed arrows). narrowing of the anterior aspect of thc disc space (cuived dashed arrows). thepart ial shearing dislract ing subluxation of Ihe posterior spinal facet (z),gapophvseal) joint processei (sol id straight arrowsl. and rhcopeninS up of the superior reccss (sol id arrowhead) and inlerior recess (open arrowhead) oithc spinal neural lbr;men. Also note thatthc opposed verlebral cndplates on either side of the degencrated L,1-5 intervertebml disc assume an antef lorl ] , directeu weugc confiSuration. This lat ier observation indicales dvsfunctional intersegnrental motion al lhN Iqvel ot diqc degcn(rat ion. a result in parr ofintersegmental l igamentopathy ( i .e.. l igamenrous laxitv/rupture).

tension p/kMRl. For this purpose. very fast acqui-sition sequences have been implemented in orderlo screen for such critical abnormalities before go-ing forward with longer time period imaging stud-ies (e.g., -4-5 minutes). Driven-equilibrium fastspin echo acquisitions offer excellent quality imag-ing in a fraction of the time (e.g., 1 NEX - l7 sec-onds) required of traditional sequences, and allowsafe imaging of almost any patient with p/kMRI(figure l3). These fast high-resolution techniquesmay in the future be a major if not only method ofimaging the spine us ing p/kMRl.

Conclusions

To conclude, the potential relative beneficial as-pects of upright, weight- bearing (pMRI), dynamic-

kinetic (kMRl) spinal imaging on this system overthat of recumbent MRI (rMRl) include: clarifica-tion of true sagittal upright neutral spinal curva-ture unaffected by patient positioning. revelationof occult degenerative spinal disease dependenton true axial loading (i.e., weighfbearing) (figure14), unmasking of kinetic-dependent degenerativespinal disease (i.e.. flexion-extension) (figures 15-17), and the potential ability to scan the patient inthe position of clinically relevant pain (figure 11)(table 9). Scanning the patient in Ihe operative po-sillon, enabling the surgeon to have a true preop-erative picture of the intraoperative pathologicmorphology, is a topic currently under investiga-tion ". This MRI unit also demonstrated low claus-trophobic potential and yielded high-resolutionimases with little motion/chemical artifact.

J ) J

Upright, WeightBearing, Dynamic-Kinetic MRI ofthe Spine J.R. Jinkins

Figure 19 Translational hypermobile instability associated withdynamic flexion-extension imaging (kMRI). A) Diagram of therecumbent spine showing degeneration of the L4-L5 interverte'bral disc and interspinous ligament (serrated lines). and degen-erative anterior spondylolisthesis of L,l (asterisk) on L5. Notethe minor narrowing of the central spinal canal (double headedarrow). B) Diagram of the upright-extended (solid curved ar-row) lumbosacral spine shows a partial reduction of the spondy-lolisthesis (dashed and solid straight arrows). Note that the cen-tral spinal canal becomes wider (double headed arrow) as com-pared to the neutral or fl€xion diagrams (A.C). C) Diagram ofthe uprighfflexed lumbosacral spine (solid curved arrow) re-veals a minor increase in the anterior translational soondvlolis-rhecis {dashed and sol id slraighl arro$s). Nore rhar ihe cenrralspinal canal becomes narrower (double headed arrow) as com-pared to the neutral or extension diagrams (A,B).

in patients with spinal, radicular and referred painsyndromes originating from spinal pathology(table 10).

This article is the proprietary property of Fonar Corporation,Melville, New York. Some or all of the contents may be used a-gain in other review publications on this subject. Fonar Corpo-ration reseNes the rights of republication after proper referenceof the present Rivista di Neuroradiologia article.

Based on initial experience with this unit, it isfelt that mid-field MRI may prove to be the opti-mal field strength for routine, anatomic MR imag-ing of the spinal column in degenerative as well asother spinal disease categories "

In addition, the evidence thus far indicates thatp/kMRI may prove to be efficacious to incorpo-rate as a part of the diagnosis-treatment paradigm

354

Rivista di Neuroradiolosia 75l.333-356.2C|J-2

References

1 Jinkins JR: Atlas of Neuroradiologic Embryology.Anatomy and Variants. Lippincott-Williams and Wilkins(ed). Phi ladelDhia 20m.

2 Jinkins JR. Gleen C. Damadian R: Upright, Weight-Bear-ing. Dynamic-Kinetic MRI of the Spine: pMRI/kMRI. Riv-ista di Neuroradioloeia l4: 135.2001.

I Smith TJ. Fernie CR: Functronal Biomechanic\ o[ theSpine. Soine l6: 1197-1203. 1991.

4 Sinith TJ: In Vitro Spinal Biomechanics: ExperimentalMethods and Apparatus. Spine l6:1204-1210. 1991.

5 Marras WS. Granata KP: A Biomechanical Assessment andModel of AxialTwisting in the Thoracolumbar Spine. Spine20r 1140-1151.1995.

6 Resnick DK.Weller SJ. BenzelEC: Biomechanics oftheTho-racolumbar Spine. Neuroslrg Clin N Amer 8:455-469. 1997.

7 Berne D. Goubier JN et Al: The Aging of the Spine. Eur JOrthop Surg Traumatol 9: 125-133. 1999.

8 Boden SD. Wiesel SW: Lumbosacral Segmental Motion inNormal Individuals: Have We Been Measurins lnstabi l i l rProperly? Spine l5: 571.57o. l99ti .

9 Danielson Bl, Wil ldn J et Al: Axial Loading of the SpineDuring CT and MR in Patients with Suspected LumbarSpinal Stenosis. Acta Radiol 39: 604-611. 1998.

l0 Frymoyer JW Frymoyer WW et Al: The Mechanical andKinematic Analysis of the Lumbar Spine in Normal LivingHuman Subiects in Vivo. J Biomech 12: 165-172,79'79.

11 Hedman TP. Fernie GR: In Vivo Measurement of LumbarSpinal Creep in Two Seated Postures Using Magnetic Res-onance Imaging. Spine 20:178-183. 1995.

12 Hilton RC. Ball J. Benn RT: In-vitro mobility of the lumbarspine. Annals Rheum Dis 38:378-383. 1979.

13 Inufusa A. An HS et Al: Anatomic Changes of the SDinalCanal anJ Intervertebral Foramen Associated With i lex-ion-Extension Movement. SDine 2l: 2412-2420. 1996.

l4 Mayoux-Benhamou MA. Revel M et At: A MorphometricStudy of the Lumbar Foramen: Influence of Flexion,Ex-tension Movements and of lsolated Disc CollaDse. SureRad io l Ana t l l r t ) 7 -102 . 198q .

l5 Nachemson AL. Schultz AB, Berkson MH: Mechanical Prop-erties ofHuman Lumbar Spine Motion Segments: lnfluencesof Age, Sex, Disc L€vel. and Degeneration. Spine 4: l-8. 1979.

16 Nowicki BH. Haughton VM et Al: Occult Lumbar LateralSpinal Stenosis in Neural Foramina Subjected to Physio-logic Loading. Am J Neuroradiol 17: 1605-1614, 1996.

l7 Pennal GF. Conn GS et Al: Motion Studies of the LumbarSpine: A Preliminary Report. J Bone Joint Surg 54B: 442-452.1912.

18 Penning L.Wilmink JT: Posture-dependent Bilateral Com-pression of L4 or L5 Nerve Roots in Facet Hypertrophy: ADynamic CI-Myelographic Study. Spine l2:488-500. 1987.

19 Schiinstrcim N, Lindahl S et Al: Dynamic Changes in theDimensions of the Lumbar Spinal Canal: An ExperimentalStudy In Vitro. J Orthop Res 7: 115-121, 1989.

20 Sortland O. Magnes B. Hauge T: Functional MyelographyWith Metrizamide in the Diagnosis of Lumbar SpinalStenosis. Acta Radio 355 (suppl): 42-54. 1977.

2l White AS. Panjabi MM: The Basic Kinematics of the Hu-man Spine: A Review of Past and Current Knowledge.SDine 3r 12-29. 1978.

22 Will6n J. Danielson B et Al: Dynamic Effects on the Lum-bar Spinal Canal: Axially Loaded CT-Myelography andMRI in Patients with Sciatica and/or Neurogenic Claudica,t ion. Spine 22:2qh8-2976. lqq7.

23 Wilmink JT, Penning L. van den Burg W Role of stenosisof spinal canal in L,1-L5 nerve root compression assessedby flexion-extension myelography. Neuroradiology 26: 173-IU l . 19 t34 .

24 Friberg O: Lumbar lnstabilityr A Dynamic Approach byTraction. Compression Radiography Spine 121 119-120, 1987.

25 Fujiwara A. An HS et Al: Morphologic Changes in theLumbar Intervertebral Foramen Due to Flexion-Extension.Lateral Bending. and Axial RotationtAn In Vitro Anatomicand Biomechanical Study. Spine 26: 876-81t2,2m1.

26 Hayes MA. Howard TC et Al: Roentgenographic Evalua-tion of Lumbar Spine Flexion-Extension in AsymptomaticIndividuals. SDine l1: 327 -331 . 1989.

27 Lee RR. Abr;ham RA, Quinn CB: Dynamic PhysiologicChanges in Lumbar CSF Volume Quantitatively MeasuredBy Three-Dimensional Fast Spin-Echo MRl. Spine 26:1112-tr78.2m.

28 Panjabi MM, Takata K, Goel VK: Kinematics of Lumbarlntervertebral Foramen. Spine 8: 348-357. 19U3.

29 Pearcy MJ.Tibrewal SB:Axial Rotation and Lateral Bend-ing in the Normal Lumbar Spine Measured by Three-Di-mensional Radiography. Spine 9: 582-587, 1984.

30 Penning L. Wilmink JT: Biomechanics of LumbosacralDural Sac. A Study of Flexion-Extension Myelography.SDine 6: 398-408. 1981.

3l Rtvel M. Mayoux-Benhamou MA et Al: Morphologicalvariations of the lumbar foramina. Rev Rhum Mal Os-teoartic 55: 361-366. 1988.

32 Stokes IA. Frvmover JW: Seemental Motion and Instabil-i tv. sDine 12:688-691. l9t i7.

-

33 Siokis IA. Wilder DG et A| Assessment of Patients withLow-Back Pain by Biplanar Radiographic Measurement ofIntervertebral Motion. Spine 6: 233-240, 1981.

34 Takayanagi K. Takahashi K et Al: Using Cineradiographyfor Continuous Dynamic-Motion Analysis of the LumbarSpine. Spine 26: 1858-1865.2001.

35 Wildermuth S, Zanetti M et Al: Lumbar Spiner Quantita-tive and Qualitative Assessment of Positional (UprightFlexion and Extension) MR Imaging and Myelography.Radiology 207: 391-398. 1998.

36 Wisleder D. Smith MB et Al: Lumbar Spine MechanicalResponse to Axial Compression Load ln Vivo. Spine 26:E403-409.2U)1.

37 Wisleder D. Werner SL et Al: A Method to Srudv LumbarSpine Response to Axial Compression During'MagneticResonance tmaging. Spine 26: E4l6-E420.2001.

38 Zamani AA. Moriarty T et Al: Functional MRI of theLumbar Spine in Erect Position in a SuperconductingOpen-Configuration MR System: Preliminary Results.JMRI 8: 1329-1333. 199tt.

39 Leviseth C. Drerup B: Spinal shrinkage during work in asitting posture compared to work in a standing posture.Clin Biomech 12: 409-418- 199'7 .

40 Lowe, RW Hayes TD et Al: Standing Roentgenograms inSpondylolisthesis. Clin Orthop 117: 80-84, 1976.

41 Devor M, Rappaport ZH: Relation of Foraminal (Lateral)Stenosis to Radicular Pain. Am J Neuroradiol l7: 1615-1617. 1996.

42 Haseeawa T. An HS et Al: Lumbar Foraminal Stenosis:CritiCal Heights of the Interyertebral Discs and Foramina.J Bone Joint Sure 77-A:32-38. 1995.

43 Pfirrmann CWA, Metzdorf A. Zanetti M: Magnetic Reso,nance Classif icarion oI Lumbar Intervertebral

-Disc Deeen-

eration. Soine 26: 1873-1878.200L44 Shiwei Y. Haughton VM. Sether LA: Criteria for Classify,

ing Normal and Degenerated Lumbar IntervertebralDisks. Neuroradiology 110: 523-526, 1989.

45 Axelsson P, Johnson R. Strttmqvist B: Is There IncreasedIntervertebral Mobility in Isthmic Adult Spondylolisthe-sis? A Matched Comparative Study Using RoentgenStereophotogrammetry. Spine 25: 1701-1703, 2000.

46 Boden SD, Frymoyer JW: Segmental Instability: Ove iewand Classification. In: Frymoyer JW (ed): The Adult Spine:Principles and Practice. Lippincott-Raven. Philadelphia1997: 21.3'l -2155.

47 Dupuis PR, Yong-Hing K et Al: Radiologic Diagnosis ofDegenerative Lumbar Spinal Instability. Spine l0: 262-216.1985.

48 Frymoyer JW Selby DK: Segmental Instability: Rationalefor Tieatment. SDine 10: 280-286. 1985.

49 Fujiwara A, Liri T-H et Al: The Effect of Disc Degenera-tion and Facet Joint Osteoarthritis on the Segmental Flex-ibi l i ty of the Lumbar Spine. Spine 25: 1016-1044.2000.

355

Uptight, Weight- Beating, Dynamic-Kinetic MRI of the Spine J.R. Jinkins

50 Pearcy M, Shepherd J: Is There Instabiliry in Spondylolis-thesis? SDine 10: 175-177.1985.

5l lto M,Tadano S. Kaneda K:A Biomechanical Definition ofSpinal Segmenral Inslabi l i ty Taking Personal and DiscLe\el Dif lerences Into Accounl. Spine l8:22t]5-2104. lgqj.

52 Pope MH, Panjabi M: Biomechaniial Definirions of Spinallnstabi l i tv SDine l0: 255-25b. 1985.

53 Sato H, kikirchi S: The Natural Hisrory of RadiographicInstability of the Lumbar Spine. Spine l8: 2075-2079, 1993.

54 Posner I.White AA et AltA Biomechanical Analvsis of theClinical Srabi l i ly of rhe Lumbar and Lumbosacial Spine.Soine 7r374-389. 1982.

55 Wood KB. Popp CA et Al: Radiographic Evaluation of In-stability in Spondylolisthesis. Spine 7: 1697-'l'703.1994.

56 Yahia H, Drouin G et Al: Degeneration of the HumanLumbar Spine Ligaments. An Ultrastructural Study. PathRes Pract 184: 369-375. 1989.

57 Fujiwara A. Tamai K et Al: The Interspinous Ligament ofthe Lumbar Spine: Magnetic Resonance Images and TheirClinical Significance. Spine 25: 358,363. 2000.

58 Adams MA. Hutton WC. Stott JRR: The Resistance toFlexion of the Lumbar Inte ertebral Joint. Spine 5:245,253. re80.

59 Dumas GA, Beaudoin L. Drouin G: In Situ MechanicalBehavior of Posterior SDinal Liqaments in the Lumbar Re-gion.An ln Vitro Study:J Biom;chanics 20:301-310. 1987.

60 Hukins DWL, Kirby MC et Al: Comparison of Structure.Mechanical Properties. and Functions of Lumbar SpinalLigaments. Spine l5: 787-795. 1990.

6l Panjabi MM: The Stabilizing System of rhe Spine. Part 1.Function. Dysfunction. Adaptation, and Enhancement. JSpinal Disorders 5: 3lt3-389. 1992.

62 Panjabi MM. Goel VK, Takata K: Physiologic Srrains in rheLumbar Spinal Ligamentst An In Vitro Biomechanical S-tudv SDine 7: 192-203.1982.

63 Sharmi M, Langrana NA. Rodriguez J: Role of Ligamenrsand Facets in Lumbar Spinal Stability. Spine 20: ti87-900.1995.

64 Fujiwara A. Lim TH,An HSrThe Effect of Disc Degenera-tion and Facet Joint Osteoarthritis on the Sesemental Flex-ibi l i ty of lhe Lumbar Sprne. Spine 25:.10.16-J044.2t(X).

65 Haughton VM. Schmidt TA et Al: Flexibility of LumbarSpinal Motion Segments Correlated toType ofTears in theAnnulus Fibrosis. J Neurosurg 92:81-86,2(D0.

66 Thompson RE, Pearcy MJ et Al: Disc Lesions and the Me-chanics of the lntervertebral Joint ComDlex. Soine 25:3026j3035.2000.

67 Twomey LT. Taylor JR: Sagittal Movements of the HumanLumbar Vertebral Column: A Quantitative Studv of theRole ot the Posrerior Verlebral Elements Arch Ph\s MedRehabil o4: 322-325. 1981.

6ll Cartolari R, Argento G et Al: Axial Loaded Computed To-mography (AL-CT) and Cine AL-CL Rivista di Neurora-diolosia I l . 1998.

69 Jinkins JR: Posttherapeutic Neurodiagnostic lmaging.Jinkins JR (ed), Lippincott-Raven. Phi ladelphia 1997.

70 Keller TS, Hansson TH et Al: In Vivo Creep Behavior oflhe Normal and Degenerated Porcrne Intervirtehral Disk:A Prel iminary Report. J Spinal Disorders l :267 -278.1989.

71 Jackson RP. Hales C: Congruent Spinopelvic Alignment onStanding Lateral Radiographs of Adult Volunteers. Spine25: 2808'21315. 2000.

72 Lee C-S, Lee C-K et Al: Dynamic Sagiftal lmbalance of theSpine in Degenerative Flat Back. Spine 26:2029-2035,2$1.

73 Jackson Rq Kanemura T et Al: Lurnbopelvic Lordosis andPelvic Balance on Repeared Standing Lateral RadiographsofAdult Volunteers and Untreated Patients with ConstantLow Back Pain. SDine 25: 575,586. 2000.

74 Jackson RB Peterson MD et Al: Compensatory Spin-opelvic Balance Over the Hip Axis and Better Reliabi l i tyin Measuring Lordosis to the Pelvic Radius on StandingLateral Radiographs of Adult Volunteers and Patients.Soine 23: 1750-1767. 1998.

75 Siephens GC, Yoo JU. Wilbur c: Comparison of LumbarSagittal Alignment Produced by Different Operative Posi,t ions. Spine 2l:1{302,1807. 1996.

76 Jinkins JR: Acquired Degenerative Changes of the Inter-ve ebral Segments at and Suprajacent to the LumbosacralJunction: a Radioanatomic Analvsis of the NondiskalStructures of the Spinal Column ;nd Perispinal Soft Tis-sues. Radiol Clin Nor Am 39: 73-99. 2001.

J. Randy Jinkins MD, FACR. FECDirector of Craniospinal Analomic Imaging ResearchDepartment of Radiological SciencesMedical College of Philadelphia-HahnemannDrexel University245 North 15'h Street - Mailstop 206Phif adef phia. PA 19 102- | 192E-mail : j r j inkins@aol.com

356