Eur Radiol (2009) 19: 2950–2952DOI 10.1007/s00330-009-1478-3 LETTER TO THE EDITOR

Mehmet ÖzkanSabahattin GündüzMurat BitekerNilüfer Ekşi DuranTahsin Güneysu

Received: 29 December 2008Revised: 6 March 2009Accepted: 6 April 2009Published online: 23 July 2009# European Society of Radiology 2009

Letter to the Editor re: Correctnessof multi-detector-row computed tomographyfor diagnosing mechanical prosthetic heartvalve disorders using operative findingsas a gold standard

Dear Editor,Multi-detector-row computed tomogra-phy is a useful technique for theevaluation of mechanical prostheticheart valve disorders.

We readwith great interest the recentreport of Tsai et al. [1] entitled“Correctness of multi-detector-rowcomputed tomography for diagnosingmechanical prosthetic heart valve dis-orders using operative findings as agold standard.” They reported thatmultidetector-row computerizedtomography (MDCT) resulted in acorrectness of 100% for diagnosingthe disease as well as localizing thedisorder. Although we agree with thediagnostic value of MDCT in theevaluation of prosthetic valve dys-function (PVD), we feel that this studyhas some major drawbacks:

(1) Since there are only two patientswith pannus out of six patients withsurgical correction, the number ofpatients is too small to consider thisconclusive information.

(2) Although transesophageal echo-cardiography (TEE) has somelimitations for assessing pannusformation, not using TEE, whichis known to be the current mostprecious and gold standard diag-nostic tool in the evaluation ofprosthetic heart valves, is anothermajor limitation.

(3) Distinction between thrombus(THR) and pannus formation canbe challenging despite improve-

ments in the imaging of themechanical prostheses providedby TEE. The use of a moreadvanced diagnostic image,MDCT, may enable us to detectthe real reason for PVD. In thisregard, the third limitation of thestudy is the absence of THRformation as a reason for PVD.Attenuation values of theabnormal masses adjacent to theprosthetic valves may providequantitative data for the differen-tiation of pannus and THRformation. However, attenuationvalues of the abnormal masses,which can also predict theresponse to thrombolytic therapy,were also not mentioned by theauthors [3]. We found that higherHounsfield unit values are sugges-tive of pannus (Fig. 1), whereas thelower values indicate THR (Fig. 2).Although an example of pannusformation is given by Tsai et al. inFig. 5, the pannus was identified asa small black area, an identificationwith which we respectfullydisagree, extending into the hous-ing. We clearly demonstrated thatpannus formation was found to be ahigh density mass in white ratherthan black, and we are convincedthat a low density mass almostalways indicates THR.

(4) In an ongoing trial [3], we haveevaluated the role of MDCT in 37patients (now 50 patients) withPVD; we have also determined the

A reply to this Letter to the Editor isavailable at doi:10.1007/s00330-009-1479-2

M. Özkan (*) . S. Gündüz .M. Biteker . N. E. DuranDepartment of Cardiology, KosuyoluKartal Heart and Research Hospital,Istanbul, Turkeye-mail: memoozkan1@gmail.comTel.: +90-532-2551513Fax: +90-216-3682527

T. GüneysuSection of CT-Angiography,Sonomed Imaging Center,Istanbul, Turkey

role of MDCT in the evaluation ofmonoleaflet valves in 8 patients,none of whom had adequate visi-bility because of excessive artifacts,in line with the study of Konen etal. [2]. Furthermore, Konen et al.have recently reported examiningthe role of aortic and mitral me-chanical valves and stated that the

visibility of monoleaflet mechanicalvalves with MDCT was limited.

Although MDCT provides some-what satisfactory delineation of PVD,there is still insufficient clinical evi-dence to make definitive recommenda-tions, and hence the authors would nothave been conclusive and enthusiastic.

In conclusion, we appreciate thestudy by Tsai et al. for their construc-tive interest in evaluating PVD byMDCT. Nevertheless, more patientswith pannus-related PVD, confirmedsurgically, should have been enrolledbecause the detection rate of pannusformation is so poor that a preopera-tive diagnosis is almost impossible.

B A

HU: 420

Fig. 1 Pannus formation surr-rounding the prosthetic mitralvalve is seen both in multi-detector computerized tomogra-phy (white arrow; a) andsurgically excised valve (blackarrow; b). Note the highHounsfield unit value (HU: 420)over the valve as a high densitymass, white in color, which issuggestive of pannus. HU:Hounsfield unit

A B

LA-THR

LAA-THR

LA HU: 62

LA

LV

HU

C

Fig. 2 Multidetector computer-ized tomography images ofprosthetic mitral valve (a), LAand LAA (b) having extensiveinvolvement of a low densitymass with low Hounsfield unitvalue (HU: 62), identified as alarge black area, which almostalways indicates thrombus. (c)Surgical finding of MMVthrombus (white arrows) isexactly the same as the multi-detector computerized tomogra-phy finding shown in (a). LA:Left atrium, LAA: left atrialappendage, LV: left ventricle,MMV: mitral mechanical valve,THR: thrombus, Ao: aorta

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References

1. Tsai IC, Lin YK, Chang Y, Fu YC,Wang CC, Hsieh SR, Wei HJ, Tsai HW,Jan SL, Wang KY, Chen MC, Chen CC(2008) Correctness of multi-detector-row computed tomography for diag-nosing mechanical prosthetic heartvalve disorders using operative findingsas a gold standard. Eur Radiol 19(4):857–867

2. Konen E, Goitein O, Feinberg MS,Eshet Y, Raanani E, Rimon U, Di-SegniE (2008) The role of ECG-gatedMDCT in the evaluation of aortic andmitral mechanical valves: initial expe-rience. AJR 191:26–31

3. Gündüz S, Duran NE, Biteker M,Güneysu T, Gökdeniz T, AstarcıoğluM, Ertürk E, Aykan AÇ, Yıldız M,Özkan M (2008) Cardiac 64-slicemultidetector computerized tomogra-phy in the management of prostheticheart valve obstruction. Circulation118:18 S–1063

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