CASE-BASED PITFALLS AND LIMITATIONS OF PIRADS v2.0

Transcription

1 CASE-BASED PITFALLS AND LIMITATIONS OF PIRADS v2.0 Antonio Luna, MD, PhD. Medical Director. Health Time. Jaén, Spain. Assistant professor of radiology. Case Western Reserve University. Cleveland, OH. Scientific director of the Spanish Society of Radiology (SERAM)

2 DISCLOSURES Consultant for Bracco Imaging (Milan, Italy) and sporadically Lecturer for GE and Toshiba in the last year. Royalties from Springer for several book publications

3 TEACHING POINTS To highlight the limitations of PIRADS version 2 in the characterization of significant prostate cancer using a case-based approach To identify false positive and negative lesions in significant cancer detection using PIRADS version 2 To review common and uncommon MRI pitfalls and tricks for significant prostate cancer detection

4 Introduction Multiparametric MRI (mpmri) has a growing impact in prostate cancer (PCa) management, being considered the most accurate imaging technique for its detection and localization, due to its ability to detect clinically significant tumors (Gleason score > 7) Recently, European Guidelines of EAU has included mp-mri as an option after a first negative transrectal-ultrasound guided biopsy (TRUS) in patients with clinical suspicion of PCa. In addition, the PIRADS v2 standard from ACR and ESUR helps to improve the reproducibility in the reading of mpmri between different centers and radiologist. Mottet N et al. EAU Prostate Cancer Guidelines 2015 Weinreb JC et al. PIRADS v

5 Introduction However, this reading system is far from being perfect, with limitations related to: o Decreased sensitivity due to false negatives cases, as there are some clinical significant PCa, which are not detectable with MRI. o Decreased specificity, as some normal anatomical structures and benign pathologies may simulate malignant disease. Mottet N et al. EAU Prostate Cancer Guidelines 2015 Weinreb JC et al. PIRADS v

6 Introduction Multiparametric MRI (mpmri) has a growing impact in prostate cancer (PCa) management, being considered the most accurate imaging technique for its detection and localization, due to its ability to detect clinically significant tumors (Gleason score > 7) Recently, European Guidelines of EAU has included mp-mri as an option after a first negative transrectalultrasound guided biopsy (TRUS) in patients with clinical suspicion of PCa. In addition, the PIRADS v2 standard from ACR and ESUR helps to improve the reproducibility in the reading of mpmri between different centers and radiologist. However, this reading system is far from being perfect, with limitations related to: o Decreased sensitivity due to false negatives cases, as there are some clinical significant PCa, which are not detectable with MRI. o Decreased specificity, as some normal anatomical structures and benign pathologies may simulate malignant disease. This review deals with the more common limitations and pitfalls of PIRADS v2 guidelines, in an intend to help radiologists to recognize these potential pitfalls. Mottet N et al. EAU Prostate Cancer Guidelines 2015 Weinreb JC et al. PIRADS v

7 Case 1: rule out significant prostate cancer DWI DCE-MRI There are 3 PCa in the prostatectomy specimen: PCa Gleason 3+4 in posterolateral right PZ, which is a PIRADS 5 lesion on MRI (red circle) PCa Gleason 3+3 in posterolateral left PZ, which is a bandlike hypointense lesion on, not clearly visible in the rest of sequences, consistent with PIRADS 2 lesion. PCa Gleason 3+3 in anterior transitional zone, which retrospectively is only seen as a tiny hypointense nodule on, without any associated abnormality in the rest of sequences (PIRADS 1).

8 PCa detection with mpmri Now PCa is considered a multifocal disease, with one index lesion and one or more additional distant secondary low-grade, low-volume lesions. This heterogeneity has limited current diagnostic pathway, as it cannot differentiate between both types of disease, leading to: o Overdiagnosis and overtreatment of low grade PCa o Underdiagnosis and undertreatment of high grade Pca Prostatectomy specimen showing multifocal PCa MRI has been introduced in the diagnostic armamentarium of PCa, as it is the most accurate imaging technique for its detection and localization, due to its outstanding ability to detect clinically significant tumors (Gleason score > 7) Ahmed, H. The Lancet Oncology, 2012; 13(11), e509 e517. Weinreb JC et al. PIRADS v

9 Case 2: 70 year-old male. PSA: 5.3 ng/ml

10 False negative lesions PCa 3+4 PCa 4+3 False negative PCa Gleason 4+3 on DWI. On right PZ, there is a band-like hypointense area on, which is not clearly visible in the rest of sequences. Prostatectomy specimen demostrates a PCa Gleason 4+3 (thunder). Asterisk represent a PCa Gleason 3+4 in anterior fibromuscular stroma not depicted on MRI images.

11 Case 3: 58 year-old male. PSA: 3.9 ng/ml DWI

12 Case 3: 58 year-old male. PSA: 3.9 ng/ml Substraction DCE-MRI Wash-in map DWI PIRADS 2 lesion: ill-defined area on WI no abnormality on and high b value DWI focal area of enhancement on left PZ (curve type 3) Gleason score (3+4) in 10% of a 1 cm core Incidental area of hemorrhage in posterolateral right PZ (arrowheads)

13 False negative lesions Low volume or small significant tumor On mpmri, tumors smaller than 0.5 cm are considered not visible. Also, it is assumed that most of the Gleason 6 tumors are not depicted with mpmri. But over this size, there are others factors that influence detection: o According to recent data, among tumor foci containing Gleason pattern 4, the only independent predictors of tumor detection were accordingly increasing tumor size and non-cribriform predominant architecture The definition of clinical significant cancer is still under debate, as: o some groups consider it any tumor with Gleason score > 7, o others separate Gleason 3+4 from Gleason over 4+3 in different prognostic groups, o others take into account the proportion of tumor burden in the biopsy cores or the proportion of Gleason 4 pattern

14 Case 4: 80 year-old male. PSA: 8.26 ng/ml DWI b 1400 * On right PZ, PIRADS 3 lesion: focal hypointense abnormality with low signal intensity on WI hypointense nodule on map not detectable on b 1400 s/mm 2 image. On targeted biopsy, a PCa Gleason 3+4 with 37% of involvement of the cores is confirmed. Lack of visibility on high b value image can be related to diffuse inflammatory changes in the rest of PZ, as it can be seen in the left posterolateral PZ on WI (asterisk)

15 Case 5: 21 year-old male with pelvic pain. PIRADS 2 lesion large well-defined mass of intermediate signal intensity on WI, which invades all the TZ. severe restriction of DWI heterogeneous peripheral enhancement, with central areas of lack of enhancement representing necrosis. b1000 DCE-MRI

16 False negative lesions Other tumors than adenocarcinoma b1000 DCE-MRI Undifferentiated sarcoma with miliary pulmonary metastases at diagnosis.

17 False negative lesions Other tumors than adenocarcinoma Sarcomas of the prostate o are rare tumours, accounting for % of all primary prostatic neoplasms. o are predominantly mesenchymal in origin but, they may also arise from stromal components o on the -weighted sequences, prostate sarcomas invariably appear as heterogeneous masses with areas of intermediate and high signal. Necrosis and cystic change in these tumours is common, because of their high malignancy and rapid growth o may demonstrate a well-defined low signal compressible pseudocapsule o usually show restriction on DWI and avid enhancement reflecting its aggressive nature

18 False negative lesions Other tumors than adenocarcinoma Rastinehard AR et al. Biomedical Data Mining 2015, 3:2 Non acinar subtypes of adenocarcinoma and sarcomas are more difficult to detect with mpmri if following strictly PIRADS v2 standard Ductal adenocarcinoma is the most common variant of nonacinar PCa (0.5-6% of all PCa). This is a very aggressive variant which behaves differently on mpmri: o Usually shows high signal intensity on WI, with similar appearance to Gleason score 6 tumors o shows restriciton of DWI and increased perfusion on DCE-MRI

19 Case 6: 49 year-old male with persistent hematuria and normal PSA level. DWI DCE PIRADS 2 lesion very large encapsulated nodule is depicted in the middle lobe, homogeneous low signal intensity on WI, restriction of diffusion and type II TIC.

20 False positive lesions : Giant Stromal BPH nodule DWI DCE 49 year-old male with persistent hematuria and normal PSA level. A very large encapsulated nodule is depicted in the middle lobe, which shows homogeneous low signal intensity on WI, restriction of diffusion and type II TIC. On targeted biopsy, a stromal BPH is demonstrated.

21 False positive lesions : Stromal BPH nodule BPH typically enlarges TZ due to hyperplasia of both the prostatic stromal and epithelial cells. BPH shows a multinodular configuration of TZ. Hyperintense nodules on WI represents hyperplastic glandular elements, which are easily differentiated from PCa with MRI Stromal and mixed nodules are most commonly hypointense on WI, and, in addition, they show restriction of water diffusion and early enhancement on DCE-MRI. Morphological criteria based on WI are the best to differentiate between stromal nodular hyperplasia and PCa of the TZ, although DWI can also help as PCa usually show a greater proportion of restriction Rarely, stromal BPH nodule can be detected in the PZ mimicking PCa.

22 False positive lesions : Stromal BPH nodule b2000 DCE-MRI MRI shows 2 stromal BPH nodules in left TZ. Both are well-defined, encapsulated, - hypointense nodules, with avid and fast enhancement and delayed washout (type 3 TIC). Both of them, also demonstrate restriction of diffusion, being more evident in the one located anteriorly. Both are PIRADS 2 lesions according to their benign appearance on WIs

23 Case 7: 63 year-old male. PSA: 6.4 ng/ml 3+3 Acute prostatitis DWI DCE PIRADS 5 lesion located on right PZ Nodular lesion, with moderate hypointense signal on WI and, marked restriction of diffusion and severe asymmetrical enhancement

24 Common in urology clinics Local (+) systemic symptomps Imaging does not form part of its normal work-up More likely in young men Caused by intraprostatic urine reflux or after prostate biopsy Histology: influx of neutrophils MRI: similar apperance to chronic prostatitis and overlaps with PCa May cause intraprostatic abscess and pelvic lymph node enlargement False positive lesions Acute prostatitis 3+3 Acute prostatitis Nodular lesion, with moderate hypo signal on WI and located on right PZ, shows marked restriction of diffusion and severe asymmetrical enhancement. It was classified as PIRADS 5. Prostatectomy specimen showed acute prostatitis. In addition, an incidental PCa Gleason 6 (3+3) was identified on anterior TZ, not detectable on MRI. DWI DCE

25 Case 8: 63 year-old male. PSA 7.2 ng/ml. DRE (+) On left PZ, PIRADS 5 lesion Markedy hypointense nodule on WI, restriction of diffusion peripheral enhancement central area of low intensity signal on all the sequences DWI DCE Acute purulent prostatitis with caseous necrosis in the prostatectomy specimen.

26 False positive lesions Acute prostatitis/abscess ababds DWI A large prostatic abscess is shown in the anterior TZ. Typical findings on MRI are demonstrates such as restriction of diffusion, peripheral enhancement and hyperintense content on TWI. This is a probably benign lesion (PIRADS 2)according to PIRADS v2 guidelines. uncommon condition, often difficult to discern clinically from acute prostatitis. focal accumulation of pus within the prostate gland. the common infecting organisms are Neisseria gonorrheae, Staphylococcus aureus and Mycobacterium tuberculosis, and also gram negative bacteria, such as Escherichia coli mainly affects diabetic and immunosuppressed patients. percutaneous transperineal or transrectal drainage under transrectal sonography is the first choice for therapy DCE

27 Case 9: 72 year-old male. PSA: 5.6 ng/ml DWI PIRADS 4 in the lateral right PZ a focal round nodule on WI (< 1.5 cm), high signal intensity on high b value DWI and low signal on.

28 False positive lesions: Chronic prostatitis Prostatitis almost always originates in the PZ often associated with elevated PSA levels, sometimes showing fluctuation, raising the suspicion of PCa. decrease of PSA with antibiotherapy favors the diagnosis Caused by undertreated acute prostatitis and recurrent infection or if lower tract infection is present. Clinically indolent. Urine culture (-) Histologically, chronic prostatitis is characterized by extracellular edema surrounding the involved prostatic cells with lymphocytes, plasma cells, macrophages, and neutrophils in the prostatic stroma. This abundance in cells as compared with normal prostatic tissue lead to an decrease. In this manner, chronic prostatitis is a common cause of false positive in targeted biopsies using areas of low as reference to define targets DWI PIRADS 4 in the lateral right PZ a focal round nodule on WI (< 1.5 cm), high signal intensity on high b value DWI and low signal on. This is biopsy proven chronic prostatitis which MRI findings cannot be differentiated from those of significant PCa.

29 MR appearance False positive lesions Acute and chronic prostatitis WI Acute prostatits Midly hypointense area with ill-defined margins May be diffuse Chronic prostatitis Ill-defined or lineal low signal intensity area in the PZ A lobar or diffuse distribution ispossible In the TZ is uncommon, but can mimic the erased charcoal sign of PCa High b value Mild to moderate hyperintense Mild to moderate hyperintensity Mild to moderate hypointense Mild to moderate hypointensity DCE-MRI Very intense and fast early enhancement, that can be diffuse and involving a greater area than the - abnormality Abscess may be a complication Acute prostatits Pitfall Similar to chronic prostatitis, may appear similar to PCa Usually even more intense enhancement than chronic prostatitis Intense and early enhancement Association to atrophy and scar Chronic prostatitis Great mimicker of significant PCa that usually shows bordeline pathological PIRADS scores Morphological criteria helps to their differentiation but they can be very similar Overlap also in their appearance in functional sequences with PCa, although chronic prostatitis usually show less restriction of diffusion than PCa. In this setting, quantification of has been proposed, as chronic prostatitis is expected to show higher values than significant PCa Trick Clinical history may help PCa is more well-defined and nodular in appearance

30 Case 10: 59 year-old male. PSA: 3.5 ng/ml DCE PIRADS 2 lesion Band-like hypointense area on axial WI with associated loss of volume. mild lineal areas of high signal intensity on DWI and low signal on corresponding map. intense and asymmetric enhancement. DWI

31 False positive lesions Glandular atrophy/postinflammatory scars DCE Band-like hypointense area on axial WI with associated loss of volume. It shows mild lineal areas of high signal intensity on DWI and low signal on corresponding map. The lesion shows intense and asymmetric enhancement. As it is not focal, suggests a PIRADS 2 abnormality, which corresponds to an area of focal atrophy of inflammatory origin. MR appearance DWI WI Focal or geographical area of low signal intesity High b value Moderately hyperintense Moderately hypointense DCE-MRI Moderate enhancement Pitfall Trick Nodule with imaging characteristics than overlap PCa in PZ Less restriction of diffusion and enhancement than significant PCa Volume loss may be associated

32 False positive lesions Postinflammatory scars DWI DCE TARGETED BIOPSY A 63 year-old male with PSA: 4 ng/ml and previous negative biopsy 5 months before. A triangular-shaped hypointense focal area of 7 mm is depicted on WI at right basal PZ, which also shows a linear area of restriction of diffusion and early enhancement. A targeted MRI/US fusion biopsy demonstrates a focal area of fibrosis at this level.

33 False positive lesions Glandular atrophy/postinflammatory scars Atrophy is a frequent finding at prostate biopsy, not mentioned by pathologist very commonly o Histologically shows crowded glands with scant cytoplasm and crowding of nuclei o Caused by inflammation, radiation, antiandrogens and chronic ischemia o Types: simple, sclerotic with cyst formation and post-atrophic hyperplastic o Direct relationship between its extent and the total or free serum elevation of PSA Postinflammatory scars usually occurs after prostatitis, and are located in the PZ Both are mimickers of PCa, and their MRI findings overlap those of chronic prostatitis

34 Case 11: 56 year-old male. PSA: 5.32 ng/ml DWI DCE Targeted biopsy: Gleason 3+4

35 Case 11: 66 year-old male with antecedent of recurrent bladder carcinoma. Persistent and progressive elevation of PSA. 4 negative previous TRUS-Bx DWI DCE On left PZ, PIRADS 3 lesion Markedy hypointense nodule on WI Midly hypointense nodule on Not detectable on DWI Perfusion (-) Granulomatous prostatitis in a patient with previous BCG injections

36 False positive lesions Granulomatous prostatitis Uncommon benign inflammatory condition Clinically is similar to PCa (firm nodule + PSA elevation) Types: o Idiopathic: more frequent, non specific and non necrotic. o Infectious: specific, non necrotic or necrotic. After intravesical bacille Calmette-Guérin (BCG) therapy or tuberculous prostatitis o Iatrogenic: postsurgical (TURP or bladder surgery) o Malacoplakia: rare granulomatous disease. Similar to PCa in MRI. o Associated with systemic granulomatous disease (sarcoidosis): rare Incidental finding in MRI for rectal cancer staging. Previous intravesical Bacille Calmette-Guérin therapy for bladder cancer. MRI depicts the presence of bladder polyps (arrowheads) on WI. MRI also shows a focal hypointense area of 17 mm on left peripheral zone on WI (arrows,) which also shows low signal intensity on map suspicious for prostate cancer. This corresponds to a PIRADS 5 lesion, confirmed as non necrotic granulomatous prostatitis

37 MR appearance WI False positive lesions Granulomatous prostatitis Non necrotic granulomatous prostatits Very hypointense discrete mass with illdefined margins and nodular to bandlike shape Necrotic granulomatous prostatits High signal intensity High b value Hyperintense Hyperintense Markedly hypointense Markedly hypointense DCE-MRI Intense enhancement Large areas of lack on enhancement= caseous necrosis, Moderate surrounding enhancement Pitfall Trick Non necrotic granulomatous prostatits Nodular lesion with similar imaging characteristics to PCa. May show extraprostatic extension Clinical history may help Only specific diagnosis is histological analysis Necrotic granulomatous prostatits Restriction of diffusion Residual patchy areas of markedly low signal intensity due to calcification fibrosis and noncaseating necrosis Areas of caseous necrosis Incidental finding in MRI for rectal cancer staging. Previous intravesical Bacille Calmette-Guérin therapy for bladder cancer. MRI depicts the presence of bladder polyps (arrowheads) on WI. MRI also shows a focal hypointense area of 17 mm on left peripheral zone on WI (arrows,) which also shows low signal intensity on map suspicious for prostate cancer. This corresponds to a PIRADS 5 lesion, posteriorly confirmed as non necrotic granulomatous prostatitis

38 False positive lesions: Pitfalls related to anatomic structures Normal anatomic structures can show a bizarre configuration and simulate PCa in mpmri Radiologist should recognize the various presentations of these normal prostatic structures Anatomic structures that may simulate PCa 1. Anterior fibromuscular stroma 2. Central zone 3. Surgical capsule 4. Periprostatic veins 5. Neurovascular bundles

39 Located in the most anterosuperior part of the prostate gland Composed of fibrous and smooth muscular elements o Absence of glandular tissue o Apical half is rich in striated muscle and blends into the gland and the muscle of the pelvic diaphragm o laterally and posteriorly, it thins to form the fibrous capsule that surrounds the prostate gland MR appearance Pitfalls related to anatomic structures Anterior fibromuscular stroma WI Marked and homogeneous hypointensity Symmetric configuration High b value Isointense b1000 b2000 DCE-MRI DCE-MRI Iso- to hypointense Absence of early enhancement Progressive enhancement (type I TIC) Normal anterior fibromuscular stroma in a 43 year-old male without signs of BPH. Anterior fibromuscular stroma is markedly hypointense on WIs, shows absence of restriction and slow and progressive enhancement on DCE-MRI.

40 Case 12: 76 year-old male with persistent and progressive elevation of PSA (PSA=5ng/mL). DWI b2000 DCE- MRI PIRADS 5 lesion in right anterior fibromuscular stroma ill-defined nodule, hypointense on WI mild restriction of diffusion enhancement (+)

41 Pitfalls related to anatomic structures Anterior fibromuscular stroma DWI b2000 Feb/2016 DWI b2000 Targeted MR/US fusion biopsy was negative for malignancy, consistent with asymmetric hyperthrophy of the anterior fibromuscular stroma Jul/2017 Pitfall Trick asymmetrical hyperthophy may show a nodular or lenticular appearance and look like PCa absence of restriction diffusion or significant early enhancement

42 Case 13: 59 year-old male. PSA: 28 ng/ml DWI b1400 DCE Targeted MR/US fusion biopsy showed a Gleason 4+4 PCa

43 Pitfalls related to anatomic structures Anterior fibromuscular stroma Pca b year-old male with PSA= 8.42 ng/ml. Systematic TRUS biopsy showed a PCa Gleason 3+3 en in right lobe in only 1 fragment with involvement of 15%. Posteriorly, MRI is performed demonstrating a highly suspicious lesion (PIRADS 5) in anterior fibromuscular stroma. Targeted biopsy revealed a PCa Gleason 8 (4+4). * b year-old male with increasing PSA up to 23.4 ng/ml. A lentiform hypointense lesion on WIs is depicted, with origin in the inferior aspect of the anterior fibromuscular stroma (asterisk), and with invasion of apical anterior TZ. The lesion shows aggressivenes both in morphological and functional sequences. Targeted MR/US fusion biopsy confirmed a PCa Gleason 4+3. DCE-MRI

44 Case 14: 62 year-old male. PSA:5.6 ng/ml DWI

45 MR appearance WI Pitfalls related to anatomic structures Central zone Its embryologic origin is from the Wolffian duct, different than the rest of the prostate gland (urogenital sinus) Represent aproximately 25% of the total prostatic volume Reduce its size in the presence of BPH, with poorer depiction on MRI Symmetric band between the PZ and TZ at the base, from below the SV to the verumontanum and surrounding the ejaculatory ducts High b value DCE-MRI Hypointense Moustache sign at the base of the prostate: Median posterior zone in the middle third of the gland Hyperintense Hypointense Progressive enhancement (type I TIC) or progressive enhancement + plateau (type 2 TIC) Uncommonly, washout (type 3 TIC) Pitfall Trick Moustache appearance of normal central zone symmetrical oval shape, sharp margins homogeneous dark signal intensity on WI asymmetrical hyperthrophy may show a nodular or lenticular appearance and look like PCa easy to recognize on coronal WI as: reversed tear drop appearance

46 Case 15: 69 year-old male. PSA: 4.6. Free/Total PSA ratio: 14%. DWI b2000 DCE-MRI On left central zone, PIRADS 5 lesion A hypointense asymmetrical nodule is identified on -weighted images with invasion of seminal vesicles restricition of diffusion and Perfusion (+), type II TIC.

47 Pitfalls related to anatomic structures Prostate cancer of the central zone Targeted MR/TRUS fusion biopsy demonstrates a Gleason 8 (4+4) PCa < 5% of PCa are located in the central zone, but are typically more aggressive Low sensitivities, but with high specificities have been reported for detection of PCa of the central zone with MRI

48 Case 16: 58 year-old male. PSA: 3.8 ng/ml. b2000 DCE-MRI On paramedian right PZ, hypointense nodule on axial TSE WI hypointense on. Absence of high signal on DWI and a tubular shape on coronal TSE-WI sugggest this is a pseudolesion, MIP of the venous phase of the DCE-MRI confirms a vascular structure at this level.

49 Located around the lateral margins of the prostate gland, closely to the prostate capsule Communicates with a plexus anterior to the prostate Pitfalls related to anatomic structures Periprostatic venous plexus b2000 MR appearance WI High b value Hypointense signal may be present Isointense DCE-MRI Hypointense DCE-MRI Early and persistent enhancement Pitfall Trick May simulate a low signal nodule on WI in the apical PZ No high signal on DWI MIP of venous enhanced series easily demonstrates the enhancing tubular vascular structure Axial TSE WI demonstrates a hypointense nodule (arrow) of paramedian right PZ, which is also hypointense on. Absence of high signal on DWI and a tubular shape on coronal TSE-WI sugggest this is a pseudolesion, as confirmed in the MIP of the venous phase of the DCE-MRI, where a vascular structure can be identified at this level.

50 Located in the posterolateral aspect of the prostate Composed of loose connective and adipose tissue containing the periprostatic venous plexus intermixed with arteries, nerves, and lymphatics Sometimes, the nerve trunks are sparsed around the lateral aspect of the prostate, without a true NV bundle are critical to mantain normal erectile function Through the NV bundles: cavernous neural plexus innervates the corpora cavernosa the prostate gland receives both parasympathetic and sympathetic innervation MR appearance Pitfalls related to anatomic structures Neurovascular bundles DCE-MRI b2000 WI High b value DCE-MRI Pitfall Trick Hypointense Isointense Signal void Progressive and predominant delayed enahncement may show a nodular appearance when viewed on face on axial plane Tubular structure on the posterolateral margin of the PZ 63 year-old male with PSA level=5 ng/ml and free to total PSA ratio=12% and 2 previous negative biopsies. A hypointense nodule is demonstrated on axial WI, which presents a band-like hypointense appearance on map, and nodular enhancement on DCE- MRI. On high b value, it is mininally hyperitense. This corresponds to a PIRADS 4 lesion, but coronal WI confirms it truly represents the right NV close to the prostatic margin.

51 Located in the posterolateral aspect of the prostate Composed of loose connective and adipose tissue containing the periprostatic venous plexus intermixed with arteries, nerves, and lymphatics Sometimes, the nerve trunks are sparsed around the lateral aspect of the prostate, without a true NV bundle are critical to mantain normal erectile function Through the NV bundles: cavernous neural plexus innervates the corpora cavernosa the prostate gland receives both parasympathetic and sympathetic innervation MR appearance Pitfalls related to anatomic structures Neurovascular bundles DCE-MRI b2000 WI High b value DCE-MRI Pitfall Trick Hypointense Isointense Signal void Progressive and predominant delayed enahncement may show a nodular appearance when viewed on face on axial plane Tubular structure on the posterolateral margin of the PZ 63 year-old male with PSA level=5 ng/ml and free to total PSA ratio=12% and 2 previous negative biopsies. A hypointense nodule is demonstrated on axial WI, which presents a band-like hypointense appearance on map, and nodular enhancement on DCE- MRI. On high b value, it is mininally hyperitense. This corresponds to a PIRADS 4 lesion, but coronal WI confirms it truly represents the right NV close to the prostatic margin.

52 Acknowledgements LIMITATIONS OF PIRADS v2 Antonio Luna MD, PhD. Health Time, Jaén. Spain. Case Medical Center. Case Western Reserve University. Cleveland, OH. Lidia Alcalá-Mata, MD. Health Time, Jaén. Spain Teodoro Martin-Noguerol, MD. Health Time, Jaén. Spain Roberto Garcia Figueiras MD; PhD. Complexo Hospitalario Santiago de Compostela, Spain. Joan C. Vilanova MD, PhD. IDI. Clinica Girona. Girona, Spain. Mariano Volpacchio, MD. Centr Diagnostico Rossi. Buenos Aires, Argentina. Violeta Catalá, MD.Fundació Puigvert. Autonoma University. Barcelona, Spain,