Applications of MRI in the diagnosis, treatment and follow up of prostate cancer

Matthew Buck

Prostate Cancer

• Second most common cause of cancer mortality in males• 1 in 8 males in UK• Increases with age• Risk factors include: ethnicity, family history, and poor

diet• 70% in peripheral zone, 25% transitional zone and 5%

central zone• Clinically significant and clinically insignificant

(Cancer Research UK, 2015; Linton and Catto, 2013; Matikane et al., 2010)

Anatomy

A B

C D

(PI-RADS V2, 2015)

Key

A: SagitalB: CornonalC: Axial BaseD: Axial Apex

PZ: Peripheral zoneCZ: Central zoneTZ: Transitional zoneUS: Urethral sphincter

AFS: Anterior fibromuscular stroma

a- anteriorp- posteriorl- lateralm- medial

Staging

Stage I- Too small to see on scans Stage II- Completely inside prostate gland

Stage III- Broken through capsule Stage IV- Spread to other organs

Diagnosis

Digital Rectal Exam (DRE)• Has a low specificity and low sensitivity• Large amount of inter-observer variability

and dependent on clinical experience

Prostate Specific Antigen (PSA)• Presence in blood indicates a disruption

in blood-prostate barrier• PSA< 10 ng/ ml = low risk• PSA 10-20 ng/ ml = intermediate risk• PSA>20 ng/ ml = high risk

Trans rectal ultrasound (TRUS)• Allows measurement of gland volume

Biopsy• TRUS or tans-perineal• Targeted to suspicious lesions or

peripheral zone• Risk of bleeding or infection

Gleeson Score• Assessment of cancerous cells• Graded 1-5 based on growth patterns• >7 = high risk

(Cancer Research UK, 2015; Linton and Catto, 2013; EAU, 2015)

MRI vs. CT vs. PET

MRI• Visualization of organ-

confined or extra-prostate spread

• Tumour location• Extracapsular spread• Seminal vesicle invasion• Bone mets

CT• Good for nodes and

distant disease• Poor visualization of

the prostate gland• Useful in MRI

contraindicated• Quick scan time• Ionising radiation• Not recommended to

low or medium risk patients (NICE, 2014)

PET• Good for metastatic

boney deposits.• Poor visualization of

the prostate gland• Ionising radiation• Not recommended in

routine clinical practice (NICE, 2014)

(NICE, 2014; Lipton and Catto, 2013)

MRI Prep

• Use of Anti-spasmodic (e.g. buscopan)• Empty bowels• Consider scanning prone• Recent biopsy may be contra-indicated• Refrain from ejaculation for 3 days prior

(Gunderson & Tepper, 2015; PI- RADS V2, 2015)

Endorectal coil vs. Phased array coil

• Increased SNR• Allows for more spatial resolution

imaging and better image quality of low SNR sequences

• Better for larger patients• More time consuming• Poor patient tolerance• Possible gland deformity• Inflation of ERC balloon causes

magnetic field inhomogeneity• Contraindication such as prior rectal

surgery, IBD, Latex allergy

• 16 channel phased array coil can provide sufficient SNR

• Less time consuming• Less traumatic for patients• Cheaper

(NICE, 2014; PI-RADS, 2015; Grand et al, 2012)

Axial Pelvis

T1

• Nodular enlargement• Loss of nodal sinus fat• Bone metastasis

T2

• Nodal involvement• Renal obstruction

• Large FOV• 5mm slice thickness

(Mankad et al, 2011; PIRADS, 2015)

Axial Prostate

T1• Presence of hemorrhage

within prostate and seminal vesicles

T2• Assess abnormalities• Seminal vesicle involvement• Nodal involvement• Extra-prostatic extension• Used for TZ lesion

measurement

• Small FOV- 120-200 mm (PI-RADS, 2015)

• 3 mm slices

(Mankad et al, 2011; PI-RADS, 2015)

T1 Axial T2 Axial

Biopsy related residual hemorrhagein right mid-peripheral zone

Large left mid-peripheralzone lesion

(Sankineni et al., 2014)

Sagittal and CoronalSagittal

• Evaluate prostate anatomy• Localisation of ER coil• Highlights invasion into bladder• Large FOV to survey of lumbar

spine and retroperitoneal for pathologies if suspected

• Used in PROMIS trial and HIFU trial

Coronal

• Evaluate prostate anatomy• Identify T2 bright and T2 dark

anatomy• Assessment of apex and base of

prostate• Bladder and seminal vesicle

assessment

Performing multi planar imaging is required for accurate measurement of the prostate gland (PI-RADS V2)

(Grand et al., 2012; PI-RADS V2, 2015)

Sagittal and Coronal

T2 Sagittal T2 Coronal

Murphy et al., 2013)

DWI• Diffusion weighted imaging• Assesses Brownian motion of molecules• Clinically significant cancers have restricted diffusion• Should include ADC• B-values acquired from 50 to 2000• High b-value can help visualize clinically significant cancers• Achieved by high b-value sequence or extrapolation from low b-value data• Primary sequence for PZ lesion measurement• Overlap with BPH and low grade tumour• Computed b-value can produce multiple b values from DWI with at least

two different b-values• High b-values have reduced SNR and increased SAR

(Bittencourt et al., 2014; PI-RADS, 2015; Ueno, et al., 2014)

DWI

(Bittencourt et al., 2014)

DCE MRI• Dynamic contrast enhanced• T1 scans before pre, during and post gadolinium• 2D or 3D- 3D imaging preferred• Ca prostate will often have early enhancement compared to

normal tissues and rapid wash out• May detect smaller, significant cancers• Secondary to T2 and DWI in PI-RADS assessment• Fat suppression can improve visualisation of enhancement• Direct visual assessment or parametric mapping

(PI-RADS, 2015; Bard, 2008; Sankineni et al., 2014)

DCE MRI

(Korobkin et al., 2014)

DCE MRI

(Bard, 2008)

T2 DCE

Spectroscopy• Prostate Ca has a high Choline content• Combined with T2- sensitivity 91% specificity 95% (Murphy et al., 2013)

• FOV voxel size is too large therefore small tumors may not be sampled

• Inoperative in the fat• Inflammation and post treatment artifacts detrimental• Specificity for low grade cancer 44% (Lemaitre et al., 2008)

• PI-RADS V2 does not recommend for routine imaging(Bard, 2009; Lemaitre et al., 2008; Murphy et al., 2013; Carroll et al., 2006)

Departmental ProtocolsStandard Protocol

• Buscopan administered• Localiser• T2 sag localiser• T1 axial large FOV • T2 coronal small FOV • T2 axial small FOV• DWI axial - b50 b400 b1000• DWI axial - b1400• T1 dynamic post contrast

PROMIS Protocol

• Localiser• T2 3 plane localiser• T2 coronal small FOV• T2 sagittal small FOV• T2 axial small FOV• DWI axial - b0 b150 b500 b1000• DWI axial - b1400• T1 dynamic vibe

Prostate CarcinomaMR features in PZ are:• A low T2 signal intensity mass • Diffusion restriction• Elevated choline peaks on MRSI• Early contrast wash-in and wash-out on DCE.• Mass effect on the adjacent capsule

MR features in TZ are:• On T2WI, area with homogenous low signal intensity, ill-defined margins,

lenticular shape and absence of a capsule and invasion of the AFS• Diffusion restriction with ill-defined margins• Asymmetric rapid contrast wash-in and wash out• Elevated choline peaks

(PI-RADS, 2015; Yu et al, 2014)

Mimics of Prostate CarcinomaChronic Pancreatitis• No contour deformity or mass effect on

adjacent normal tissue• Decreased T2 signal but DWI signal is

often less than prostate ca• Mild contrast wash-in and wash-out on

DCE

Hypertrophic nodules• Well defined margins; rounded or

spherical• Rapid contrast wash-in and wash-out

on DCE

Focal changes related to prior radiation• Lack of significant diffusion restriction• No rapid wash-in or wash-out on DCE• No elevation of choline peaks

Benign prostatic hyperplasia (BPH)• Found in TZ but can extrude to PZ• Glandular nodes have Moderate T2

hyper-intensity• Encapsulated with round nodules

and circumscribed margins• Stroma nodules have T2 hypo-

intensity• On DCE, Prostate Ca has stronger

enhancement with earlier peak time (p< 0.05).• ADCs are higher in BPH than

prostate ca

(Yu et al., 2014; PI-RADS, 2015; Ren et al., 2007)

Role of MRI in treatment and follow-up of Prostate Ca

• External beam radiation therapy (EBRT) and Brachytherapy are used in patients with tumour extension beyond prostatic capsule and in patients opting for primary or salvage treatment

• T2WI has a higher soft tissue contrast than CT and Transrectal US , as it provides more accurate identification and localisation of the tumour and gives more accurate delineation of irradiation field and decreases dose to periprostatic tissues and urethra.

• Brachytherapy prostate Ca patients only to be imaged at 1.5T, due to artifact from gold beads

• However, radiotherapy can cause diffuse T2 signal• T2 imaging is limited by loss of zonal anatomy glandular atrophy and fibrosis• Low signal T2, low signal ADC and rapid wash out on DCE • DCE has better sensitivity (72%) than T2 (38%) for localisation of recurrent prostate

cancer (Haider et al., 2008)

• MRS can be added to examination to aid diagnosis as elevated choline levels with absence of citrate suggest recurrent prostate carcinoma

(Westphalen et al.,2008,;Murphy et al., 2013, Haider et al., 2008; Yu et al., 2014)

ReferencesAmerican Journal of Urology. (2015). PI-RADS V2 Prostate imaging- reporting and data system. ACR Bard, R. L. (2009). Dynamic contrast enhanced MRI. Berlin: Springer Bhavsar, A. & Verma, S. (2014). Anatomic imaging of the prostate. BioMed Research International. doi: 10.1155/2014/728539 Bittencourt, L. K. Attenberger, U. I. Lima, D. Strecker, R. de Oliverira, A. Schoenberg, S. O. … & Hausmann, D. (2014).

Feasibility study of computed vs measured high b- value (1400 s/mm²) diffusion-weighted MR images of the prostate. World Journal of Radiology, 6(6). 374-380. doi: 10.4329/wjr.v6.i6.374

Cancer Research UK. (2015). Prostate cancer mortality statistics. Cancer Research UK. Retrieved January 10th 2016 form:http://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/prostate-cancer/mortality European Association of Urology. (2015). Guidelines to prostate cancer. EAU. Arnhem. Mottet, N.

Grand, D. J. Mayo-Smith, W. W. Woofield, C. A. (2012). Practical body MRI: protocols, applications and image interpretation. New York: Cambridge University Press Gunderson, L. L. & Tepper, J. E. (2015). Clinical radiation oncology. (4th Ed.). China: Elsevier

Haider, M. A. Chung, P. Sweet, J. Toi, A. Jhaveri, K. Menard, D. … & Milosevic, M. (2008). Dynamic contrast enhanced MRI for localisation of recurrent prostate cancer after after external beam radiotherapy. Internation

Journal of Radiation Oncology. 70(2). 425-430. doi:10.1016/j.ijrobp.2007.06.029

ReferencesKorobkin, A. Serova, N. Ustyuzhanin, I. Korobkova, G & Voskanyan, A. (2014).

Diagnostic value of modern MRI technique. ECR. Doi: 10.1594/ecr2014/C-1482

Linton, K. D. & Catto, J. W. F. 2013. Prostate cancer, Renal and Urological Surgery II. 31(10). 516-522

Mankad, K. Hoey, E. Lakkaraju, A. Bhuskute, N. (2011). MRI of the whole body: an illustrated guide to common pathologies. Florida: Hodder Arnold

Murphy, G. Haider, M. Ghai, S. & Sreeharsaha, B. (2013). The expanding role of MRI in prostate cancer. American Journal of Radiology, 201. 1229-1239. doi. 10.2214/AJR.12.10178

National Institute for Health and Care Excellence. (2014). Prostate Cancer: Diagnosis and Management. London. NICE.

Ren, J. Huan, Y. Wang, H. Chang, Y. –J. Zhao, H. –T. Ge, Y. –L. … & Yang, Y. (2008). Dynamic contrast enhanced MRI of benign prostatic hyperplasia and prostatic carcinoma: correlation with angiogenesis. Clinical Radiology. 63. 153-159. doi:10.1016/j.crad.2007.07.023

Sankineni, S. Osman, M. & Choyke, P. L. (2014). Functional MRI in prostate cancer detection. Bio-Med Research International. doi: 10.1155/2014/590638

National Institute for Health and Care Excellence. (2014). Prostate Cancer: Diagnosis and Management. London. NICE.

References Ueno, Y. Takahashi, S. Ohno, Y. Kitajima, K. Yui, M. Kassai, Y. Kawakami, F. … & Sugimura, K. (2014). Computed

diffusion-weighted MRI for prostate cancer detection: the influence of the combinations of b-values. British Journal of Radiology. 88(1048). doi. 0.1259/bjr.20140738

Westphalen, A.C. McKenna, D. A. Kurhanewicz, J. & Coakley, F.V. (2009). Role of MRI and MRI spectroscopic imaging before and after radiotherapy for prostate cancer. Journal of Endourology, 24(4). 789-794 10.1089/end.2007.9822

Yu, J. Flucher, A. S. Turner, M. A. Cockrell, C. H. Cote, E. P. & Wallace, T. J. (2014). Prostate cancer and its

mimics at multiparametric prostate MRI. British Institute of Radiology, 87(1037)doi. 10.1259/bjr. 20130659