How to improve image quality of DWI of the prostate-enema or catheter preparation?

OBJECTIVES

To compare the impact of laxative enema preparation versus air/gas suction through a small catheter on image quality of prostate DWI.

METHODS

In this single-center study, 200 consecutive patients (100 in each arm) with either enema or catheter preparation were retrospectively included. Two blinded readers independently assessed aspects of image quality on 5-point Likert scales. Scores were compared between groups and the influence of confounding factors evaluated using multivariable logistic regression. Prostate diameters were compared on DWI and T₂-weighted imaging using intraclass correlation coefficients.

RESULTS

Image quality was significantly higher in the enema group regarding the severity of susceptibility-related artifacts (reader 1: 0.34 ± 0.77 vs. 1.73 ± 1.34, reader 2: 0.38 ± 0.86 vs. 1.76 ± 1.39), the differentiability of the anatomy (reader 1: 3.36 ± 1.05 vs. 2.08 ± 1.31, reader 2: 3.37 ± 1.05 vs. 2.09 ± 1.35), and the overall image quality (reader 1: 3.66 ± 0.77 vs. 2.26 ± 1.33, Reader 2: 3.59 ± 0.87 vs. 2.23 ± 1.38) with almost perfect inter-observer agreement (κ = 0.92-0.95). In the enema group, rectal distention was significantly lower and strongly correlated with the severity of artifacts (reader 1: ρ = 0.79, reader 2: ρ = 0.73). Furthermore, there were significantly fewer substantial image distortions, with odds ratios of 0.051 and 0.084 for the two readers which coincided with a higher agreement of the prostate diameters in the phase-encoding direction (0.96 vs. 0.89).

CONCLUSIONS

Enema preparation is superior to catheter preparation and yields substantial improvements in image quality.

KEY POINTS

• Enema preparation is superior to decompression of the rectum using air/gas suction through a small catheter. • Enema preparation markedly improves the image quality of prostate DWI regarding the severity of susceptibility-related artifacts, the differentiability of the anatomy, and the overall image quality and considerably reduces substantial artifacts that may impair a reliable diagnosis.

Pitfalls in Prostate Cancer Magnetic Resonance Imaging

Image-guided prostate biopsies are changing the outlook of prostate cancer (PCa) diagnosis, with the degree of suspicion on multiparametric magnetic resonance imaging (mp-MRI) being a strong predictor of targeted biopsy outcome. It is important not only to detect these suspicious lesions but also to be aware of the potential pitfalls in mp-MRI prostate imaging. The aim of this pictorial essay is to show a wide spectrum of representative cases, which are frequently misdiagnosed as PIRADS ⅘ while reporting mp-MRI of the prostate. We provide some valuable recommendations to avoid these fallacies and improve mp-MRI of prostate evaluation.

Prostatitis: imaging appearances and diagnostic considerations

Acute and chronic inflammation of the prostate gland can be attributed to several underlying aetiologies, including but not limited to, bacterial prostatitis, granulomatous prostatitis, and Immunoglobulin G4-related prostatitis. In this review, we provide an overview of the general imaging appearances of the different types of prostatitis, their distinguishing features and characteristic appearances at cross-sectional imaging. Common imaging pitfalls are presented and illustrated with examples.

Multiparametric MRI Lesion Classified as Prostate Imaging-Reporting and Data System 5 but Histopathologically Described as Benign: A Case Report and Review of Literature

INTRODUCTION

Prostate cancer (PCa) is the most common malignancy in men. The multiparametric MRI (mpMRI) significantly improved the diagnostic approach of PCa. Although PCa is highly likely to be present in prostate imaging-reporting and data system (PI-RADS) 5 lesions, there are up to 18% of PI-RADS 5 lesions with benign histopathology after targeted biopsy.

CASE DESCRIPTION

We present the case of a 66-year-old man who was referred to our hospital for MRI/ultrasound fusion-based targeted biopsy due to an elevated PSA and a PI-RADS 5 lesion described in the mpMRI. After 2 consecutive biopsies, the mpMRI target showed no malignancy. The lesion was described as PI-RADS 2 two years later.

CONCLUSION

This case demonstrates the risk of false-positive classified PI-RADS 5 lesions in the mpMRI and the challenge in some cases to distinguish between BPH nodules and cancer. Until today, a limited amount of studies exists concerning this issue. However, further studies are required to evaluate further characteristics associated with a higher possibility of histopathologically benign findings in PI-RADS 5 lesions.

The Clinical and Pathologic Relevance of a Prostate MRI Diagnosis of "Prostatitis"

OBJECTIVE

To investigate the relationship between magnetic resonance imaging evidence of prostatitis with clinical symptomatology. Non-malignant abnormalities in peripheral zone are common in prostate multiparametric prostate magnetic resonance imaging (mpMRI). These findings are sometimes reported as "prostatitis" or "inflammation" and lead to patient anxiety and urologic referral.

METHODS

Retrospective review of patients undergoing prostate mpMRI (2016-2017) was performed. Two cohort groups based on the presence of "prostatitis" or "inflammation" in the radiology report were identified. Clinical characteristics included age, prostate specific antigen, biopsy/intervention history, true lower urinary tract symptoms (LUTS), pain, use of urologic medications, prostate volume, and PIRADS score. Pathologic finding of inflammation was recorded. Groups were compared using chi-square for dichotomous variables and t-tests for continuous variables.

RESULTS

One hundred and four patients were identified with "prostatitis/inflammation" and 273 without. Report of LUTS was high in both groups (58% and 62% for prostatitis and no prostatitis respectively, P= .49), though report of moderate/severe LUTS (physician description or IPSS of 8-19 and 20+) was more common in the no prostatitis group (7% vs 18%, P= .008). Use of urologic medication was similar between the 2 groups (31% and 37% for prostatitis and no prostatitis respectively, P = .23). Biopsy finding of inflammation was more common in the prostatitis group (57% vs 43% P = .027). Reports of pelvic pain, dysuria, or urinary findings of inflammation were uncommon in both groups.

CONCLUSION

While mpMRI findings of prostatitis may indicate NIH Category IV prostatitis, there is no evidence of correlation with categories I, II or III prostatitis nor with symptomatic LUTS, and patients should be reassured that further investigation is not warranted.

Prostate Multiparametric MRI: Common Pitfalls in Primary Diagnosis and How to Avoid Them

Purpose of Review

To provide the radiologist with basic knowledge about normal and abnormal findings in the prostatic mp-MRI, taking a look at the possible diagnostic pitfalls commonly seen in daily clinical practice, allowing him to recognize and consequently avoid them.

Recent Findings

Prostate mp-MRI has now become commonly used in most diagnostic imaging centers, as a precise, accurate and above all non-invasive tool, useful in the diagnosis, staging and follow-up of prostate diseases, first of all prostatic carcinoma. For this reason, it is important to take into account the existence of numerous possible anatomic and pathologic processes which can mimick or masquerade as prostate cancer.

Summary

Through the combination of anatomical (T2WI) and functional sequences (DWI/ADC and DCE), the mp-MRI of the prostate provides all the information necessary for a correct classification of patients with prostate disease, cancer in particular. It is not uncommon, however, for the radiologist to make errors in the interpretation of imaging due to conditions, pathological or otherwise, that mimic prostate cancer and that, consequently, affect the diagnostic/therapeutic process of patients. The strategy, and what this pictorial review aims at, is to learn to recognize the potential pitfalls of the prostatic mp-MRI and avoid them.

Quantitative measurements of prostatic zones by MRI and their dependence on prostate size: possible clinical implications in prostate cancer

AIM

Many studies support an inverse relationship between benign prostate hypertrophy (BPH) size and incidence of prostate cancer (PCa), but the causal link between these conditions is poorly understood. Recent studies suggest that a growing transition zone (TZ) in the prostate may induce pressure on the outer peripheral zone (PZ), leading to atrophy of the glandular tissue where PCa often originates, providing a possible explanation for this interaction. To further investigate this phenomenon, our pilot study uses magnetic resonance imaging (MRI) to examine quantitative zonal changes in a consecutive cohort of prostates.

METHODS

MRI scans of male patients [n = 204, 61.57 ± 13.90 years, average body mass index (BMI) 29.05 kg/m2] with various prostate sizes were analyzed statistically to identify possible associations between prostate parameters, such as total prostate volume (TPV) and peripheral zone thickness (PZT).

RESULTS

TPV and PZT demonstrated a weak, inverse correlation (r = -0.21, p = 0.002). However, when examining the plotted data, the relationship between TPV and PZT was significantly different when the cohort was divided into two groups; lower TPV: ⩽87.5 ml (n = 188, TPV x- = 36.01 ± 18.18 ml), and higher TPV: >87.5 ml (n = 17, TPV x- = 125.69 ± 41.13 ml). Average PZT differed significantly between these groups (z = -3.5554, p = 0.0004).

CONCLUSIONS

PZT was significantly different for patients with lower versus higher TPVs, suggesting that, above a certain point of BPH growth, the PZ is unable to withstand pressure from an expanding TZ, supporting the notion that growing BPH causes compression of the PZ glandular tissue, and, therefore, BPH may be protective against PCa.

Rectal gas-induced susceptibility artefacts on prostate diffusion-weighted MRI with epi read-out at 3.0 T: does a preparatory micro-enema improve image quality?

PURPOSE

To assess whether the application of a preparatory micro-enema reduces gas-induced susceptibility artefacts on diffusion-weighted MRI of the prostate.

METHODS

114 consecutive patients who received multiparametric 3 T MRI of the prostate at our institution were retrospectively enrolled. 63 patients self-administered a preparatory micro-enema prior to imaging, and 51 patients underwent MRI without bowel preparation. Two blinded readers independently reviewed the diffusion-weighted sequences regarding gas-induced artefacts. The presence/severity of artefacts was scored ranging from 0 (no artefact) to 3 (severe artefact). A score ≥ 2 was considered a clinically relevant artefact. Maximum rectal width at the level of the prostate was correlated with the administration of a micro-enema. Scores were compared between the scans performed with and without bowel preparation using univariable and multivariable logistic regression, taking into account potential confounding factors (age and prostate volume).

RESULTS

Significantly less artefacts were found on diffusion-weighted sequences after the administration of a micro-enema shortly prior to MR imaging. Clinically relevant artefacts were found in 10% in the patient group after enema, in 41% without enema. If present, artefacts were also significantly less severe. Mean severity score was 0.3 (enema administered) and 1.2 (no enema), and odds ratio was 0.137 (p < 0.0001) in univariable ordinal logistic regression. Inter-observer agreement was excellent (κ 0.801).

CONCLUSION

The use of a preparatory micro-enema prior to 3 T multiparametric prostate MRI significantly reduces both the incidence and severity of gas-induced artefacts on diffusion-weighted sequences and thus improves image quality.

Isotropic Expansion of the Intraprostatic Gross Tumor Volume of Primary Prostate Cancer Patients Defined in MRI-A Correlation Study With Whole Mount Histopathological Information as Reference

Introduction

An accurate delineation of the intraprostatic gross tumor volume (GTV) is of importance for focal treatment in patients with primary prostate cancer (PCa). Multiparametric MRI (mpMRI) is the standard of care for lesion detection but has been shown to underestimate GTV. This study investigated how far the GTV has to be expanded in MRI in order to reach concordance with the histopathological reference and whether this strategy is practicable in clinical routine.

Patients and Methods

Twenty-two patients with planned prostatectomy and preceded 3 Tesla mpMRI were prospectively examined. After surgery, PCa contours delineated on histopathological slides (GTV-Histo) were superimposed on MRI using ex-vivo imaging as support for co-registration. According to the PI-RADSv2 classification, GTV was manually delineated in MRI (GTV-MRI) by two experts in consensus. For volumetric analysis, we compared GTV-MRI and GTV-Histo. Subsequently, we isotropically enlarged GTV-MRI in 1 mm increments within the prostate and also compared those with GTV-Histo regarding the absolute volumes. For evaluating the spatial accuracy, we considered the coverage ratio of GTV-Histo, the Sørensen–Dice coefficient (DSC), as well as the contact with the urethra.

Results

In 19 of 22 patients MRI underestimated the intraprostatic tumor volume compared to histopathological reference: median GTV-Histo (4.7 cm³, IQR: 2.5–18.8) was significantly (p<0.001) lager than median GTV-MRI (2.6 cm³, IQR: 1.2–6.9). A median expansion of 1 mm (range: 0–4 mm) adjusted the initial GTV-MRI to at least the volume of GTV-Histo (GTV^exp-MRI). Original GTV-MRI and expansion with 1, 2, 3, and 4 mm covered in median 39% (IQR: 2%–78%), 62% (10%–91%), 70% (15%–95%), 80% (21–100), 87% (25%–100%) of GTV-Histo, respectively. Best DSC (median: 0.54) between GTV-Histo and GTV-MRI was achieved by median expansion of 2 mm. The urethra was covered by initial GTVs-MRI in eight patients (36%). After applying an expansion with 2 mm the urethra was covered in one more patient by GTV-MRI.

Conclusion

Using histopathology as reference, we demonstrated that MRI underestimates intraprostatic tumor volume. A 2 mm–expansion may improve accurate GTV-delineation while respecting the balance between histological tumor coverage and overtreatment.

Fusion US/MRI prostate biopsy using a computer aided diagnostic (CAD) system

BACKGROUND

The aim of this study was to investigate the impact of computer aided diagnostic (CAD) system on the detection rate of prostate cancer (PCa) in a series of fusion prostate biopsy (FPB).

METHODS

Two prospective transperineal FPB series (with or without CAD assistance) were analyzed and PCa detection rates compared with per-patient and per-target analyses. The χ² and Mann-Whitney test were used to compare categorical and continuous variables, respectively. Univariable and multivariable regression analyses were applied to identify predictors of any and clinically significant (cs) PCa detection. Subgroup analyses were performed after stratifying for PI-RADS Score and lesion location.

RESULTS

Out of 183 FPB, 89 were performed with CAD assistance. At per-patient analysis the detection rate of any PCa and of cs PCa were 56.3% and 30.6%, respectively; the aid of CAD was negligible for either any PCa or csPCa detection rates (P=0.45 and P=0.99, respectively). Conversely in a per-target analysis, CAD-assisted biopsy had significantly higher positive predictive value (PPV) for any PCa versus MRI-only group (58% vs. 37.8%, P=0.001). PI-RADS Score was the only independent predictor of any and csPCa, either in per-patient or per-target multivariable regression analysis (all P<0.029). In a subgroup per-patient analysis of anterior/transitional zone lesions, csPCa detection rate was significantly higher in the CAD cohort (54.5%vs.11.1%, respectively; P=0.028), and CAD assistance was the only predictor of csPCa detection (P=0.013).

CONCLUSIONS

CAD assistance for FPB seems to improve detection of csPCa located in anterior/transitional zone. Enhanced identification and improved contouring of lesions may justify higher diagnostic performance.

Prostate MRI: practical guidelines for interpreting and reporting according to PI-RADS version 2.1

The increasing precision of multiparametric magnetic resonance imaging of the prostate, together with greater experience and standardization in its interpretation, has given this technique an important role in the management of prostate cancer, the most prevalent non-cutaneous cancer in men. This article reviews the concepts in PI-RADS version 2.1 for estimating the probability and zonal location of significant tumors of the prostate, using a practical approach that includes current considerations about the prerequisites for carrying out the test and recommendations for interpreting the findings. It emphasizes benign findings that can lead to confusion and the criteria for evaluating the probability of local spread, which must be included in the structured report.

Prostatitis, the Great Mimicker of Prostate Cancer: Can We Differentiate Them Quantitatively With Multiparametric MRI?

OBJECTIVE. The purpose of this study was to investigate the diagnostic performance of semiquantitative and quantitative pharmacokinetic parameters and quantitative apparent diffusion coefficient (ADC) values obtained from prostate multiparametric MRI (mpMRI) to differentiate prostate cancer (PCa) and prostatitis objectively. MATERIALS AND METHODS. We conducted a retrospective review of patients with biopsy-proven PCa or prostatitis who underwent mpMRI study between January 2015 and February 2018. Mean ADC, forward volume transfer constant (K^trans), reverse volume transfer constant (k_ep), plasma volume fraction (V_p), extravascular extracellular space volume fraction (V_e), and time to peak (TTP) values were calculated for both lesions and contralateral normal prostate tissue. Signal intensity-time curves were analyzed. Lesion-to-normal prostate tissue ratios of pharmacokinetic parameters were also calculated. The diagnostic accuracy and cutoff points of all parameters were analyzed to differentiate PCa from prostatitis. RESULTS. A total of 138 patients (94 with PCa and 44 with prostatitis) were included in the study. Statistically, ADC, quantitative pharmacokinetic parameters (K^trans, k_ep, V_e, and V_p), their lesion-to-normal prostate tissue ratios, and TTP values successfully differentiated PCa and prostatitis. Surprisingly, we found that V_e values were significantly higher in prostatitis lesions. The combination of these parameters had 92.7% overall diagnostic accuracy. ADC, k_ep, and TTP made up the most successful combination for differential diagnosis. Analysis of the signal intensity-time curves showed mostly type 2 and type 3 enhancement curve patterns for patients with PCa. Type 3 curves were not seen in any prostatitis cases. CONCLUSION. Quantitative analysis of mpMRI differentiates PCa from prostatitis with high sensitivity and specificity, appears to have significant potential, and may improve diagnostic accuracy. In addition, evaluating these parameters does not cause any extra burden to the patients.

T1 and T2 MR fingerprinting measurements of prostate cancer and prostatitis correlate with deep learning-derived estimates of epithelium, lumen, and stromal composition on corresponding whole mount histopathology

OBJECTIVES

To explore the associations between T1 and T2 magnetic resonance fingerprinting (MRF) measurements and corresponding tissue compartment ratios (TCRs) on whole mount histopathology of prostate cancer (PCa) and prostatitis.

MATERIALS AND METHODS

A retrospective, IRB-approved, HIPAA-compliant cohort consisting of 14 PCa patients who underwent 3 T multiparametric MRI along with T1 and T2 MRF maps prior to radical prostatectomy was used. Correspondences between whole mount specimens and MRI and MRF were manually established. Prostatitis, PCa, and normal peripheral zone (PZ) regions of interest (ROIs) on pathology were segmented for TCRs of epithelium, lumen, and stroma using two U-net deep learning models. Corresponding ROIs were mapped to T2-weighted MRI (T2w), apparent diffusion coefficient (ADC), and T1 and T2 MRF maps. Their correlations with TCRs were computed using Pearson's correlation coefficient (R). Statistically significant differences in means were assessed using one-way ANOVA.

RESULTS

Statistically significant differences (p < 0.01) in means of TCRs and T1 and T2 MRF were observed between PCa, prostatitis, and normal PZ. A negative correlation was observed between T1 and T2 MRF and epithelium (R = - 0.38, - 0.44, p < 0.05) of PCa. T1 MRF was correlated in opposite directions with stroma of PCa and prostatitis (R = 0.35, - 0.44, p < 0.05). T2 MRF was positively correlated with lumen of PCa and prostatitis (R = 0.57, 0.46, p < 0.01). Mean T2 MRF showed significant differences (p < 0.01) between PCa and prostatitis across both transition zone (TZ) and PZ, while mean T1 MRF was significant (p = 0.02) in TZ.

CONCLUSION

Significant associations between MRF (T1 in the TZ and T2 in the PZ) and tissue compartments on corresponding histopathology were observed.

KEY POINTS

• Mean T2 MRF measurements and ADC within cancerous regions of interest dropped with increasing ISUP prognostic groups (IPG). • Mean T1 and T2 MRF measurements were significantly different (p < 0.001) across IPGs, prostatitis, and normal peripheral zone (NPZ). • T2 MRF showed stronger correlations in the peripheral zone, while T1 MRF showed stronger correlations in the transition zone with histopathology for prostate cancer.

Prostate MR: pitfalls and benign lesions

Multiparametric MRI (mpMRI) of the prostate has evolved to be an integral component for the diagnosis, risk stratification, staging, and targeting of prostate cancer. However, anatomic and histologic mimics of prostate cancer on mpMRI exist. Anatomic feature that mimic prostate cancer on mpMRI include anterior fibromuscular stroma, normal central zone, periprostatic venous plexus, and thickened surgical capsule (transition zone pseudocapsule). Benign conditions such as post-biopsy hemorrhage, prostatitis or inflammation, focal prostate atrophy, benign prostatic hyperplasia nodules, and prostatic calcifications can also mimic prostate cancer on mpMRI. Technical challenges and other pitfalls such as image distortion, motion artifacts, and endorectal coil placements can also limit the efficacy of mpMRI. Knowledge of prostate anatomy, location of the lesion and its imaging features on different sequences, and being familiar with the common pitfalls are critical for the radiologists who interpret mpMRI. Therefore, this article reviews the pitfalls (anatomic structures and technical challenges) and benign lesions or abnormalities that may mimic prostate cancer on mpMRI and how to interpret them.

Prostate magnetic resonance imaging technique

Multiparametric magnetic resonance (MR) imaging of the prostate is an excellent tool to detect clinically significant prostate cancer, and it has widely been incorporated into clinical practice due to its excellent tissue contrast and image resolution. The aims of this article are to describe the prostate MR imaging technique for detection of clinically significant prostate cancer according to PI-RADS v2.1, as well as alternative sequences and basic aspects of patient preparation and MR imaging artifact avoidance.

Quantitative measurements of prostate capsule and gland density and their correlation to prostate size: possible clinical implications in prostate cancer

PURPOSE

To study histo-anatomical imaging features and possible association between prostate volume, capsule thickness and glandular density within the peripheral zone (PZ) of prostates of different sizes.

METHODS

Patients were selected who had undergone radical prostatectomy. Specimen selection was based on two factors: first, easy reconstruction of prostate anatomy by the histological slides; and second, based on prostate size. Specimens were chosen with small (< 35 cc) and also with large size (> 80 cc). A total of 20 patients were selected. None of these patients had undergone previous treatment. Computer-based imaging for quantitative measurements of capsule thickness and glandular density within the PZ were performed. Multiple regression analysis was performed to determine the relationship between these measured parameters and the clinical characteristics of these patients.

RESULTS

Multiple regression analysis revealed a strong, positive association between prostate size and average capsule thickness; on the contrary, we found a negative correlation between prostate volume and average glandular density. Fibrotic thickness of the capsule was associated with gland atrophy and decreased gland density within the PZ.

CONCLUSIONS

The results suggest that BPH may be associated with the development of fibrosis and gland atrophy within the peripheral zone. As 80% of prostate cancer originates from the glandular epithelium within the peripheral zone, this observed phenomenon may explain the inverse relationship between BPH and incidence of prostate cancer well documented in the literature.

Quantitative Prostate MRI

Prostate MRI is reported in clinical practice using the Prostate Imaging and Data Reporting System (PI-RADS). PI-RADS aims to standardize, as much as possible, the acquisition, interpretation, reporting, and ultimately the performance of prostate MRI. PI-RADS relies upon mainly subjective analysis of MR imaging findings, with very few incorporated quantitative features. The shortcomings of PI-RADS are mainly: low-to-moderate interobserver agreement and modest accuracy for detection of clinically significant tumors in the transition zone. The use of a more quantitative analysis of prostate MR imaging findings is therefore of interest. Quantitative MR imaging features including: tumor size and volume, tumor length of capsular contact, tumor apparent diffusion coefficient (ADC) metrics, tumor T₁ and T₂ relaxation times, tumor shape, and texture analyses have all shown value for improving characterization of observations detected on prostate MRI and for differentiating between tumors by their pathological grade and stage. Quantitative analysis may therefore improve diagnostic accuracy for detection of cancer and could be a noninvasive means to predict patient prognosis and guide management. Since quantitative analysis of prostate MRI is less dependent on an individual users' assessment, it could also improve interobserver agreement. Semi- and fully automated analysis of quantitative (radiomic) MRI features using artificial neural networks represent the next step in quantitative prostate MRI and are now being actively studied. Validation, through high-quality multicenter studies assessing diagnostic accuracy for clinically significant prostate cancer detection, in the domain of quantitative prostate MRI is needed. This article reviews advances in quantitative prostate MRI, highlighting the strengths and limitations of existing and emerging techniques, as well as discussing opportunities and challenges for evaluation of prostate MRI in clinical practice when using quantitative assessment. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 2.

Effects of "real life" prostate MRI inter-observer variability on total needle samples and indication for biopsy

PURPOSE

Prostate multiparametric magnetic resonance imaging (mpMRI) improves diagnosis of clinically significant cancer and reduces over-detection of nonsignificant cancer. Disagreement in the interpretation of mpMRI readings is well-known, with a reported discrepancy rate of 10% to 42%. We report the clinical repercussions of this variability on prostate biopsy candidates.

MATERIALS AND METHODS

Medical records of patients referred from 11 medical centers for MR-guided prostate biopsy (MRGpB) between October, 2017 and January, 2019 were retrospectively analyzed. Patients with at least one prostate imaging reporting and data system (PI-RADS) 3 or greater prostate lesion were selected, and the mpMRI studies (all read by others) were reviewed by our prostate mpMRI reader. Outcomes included changes in PI-RADS score and the subsequent effect on total needle samples and indication for biopsy.

RESULTS

Eighty-two patients with 128 lesions were suitable for analysis (mean age 66.5 ± 7.1 years, mean PSA 6.8 ± 8.5 ng/ml). Nine (11%) patients had suspicious rectal exams (T2a). Following our prostate mpMRI reader's imaging revisions, the PI-RADS score was downgraded in 66 (52%) lesions, upgraded in 15 (12%), and unchanged in 47 (37%), leaving a total of 84 suspected lesions (kappa = 0.17). Biopsy was deferred in 22 (27%) patients, and an estimated 136.4 (34.4%) samples were avoided (P = 0.0001 for both). There was a trend toward prostate size to correlate with imaging revision and abortion of biopsy (P = 0.06) while enrollment in active surveillance correlated with proof from such outcome (P = 0.007).

CONCLUSION

These data suggest that high interobserver disagreement in prostate mpMRIs from diverse institutes significantly affects prostate biopsy practice. The clinical consequences of this discord are significant.

What You Need to Know Before Reading Multiparametric MRI for Prostate Cancer

OBJECTIVE. Multiparametric MRI (mpMRI) has become the main imaging modality for the detection, localization, and local staging of prostate cancer over the past decade. For radiologists to achieve consistent and reproducible reporting of prostate mpMRI, a comprehensive evaluation of the gland including detailed knowledge of anatomy, pathology, and clinical data is required. This article familiarizes radiologists with common pitfalls and conditions that affect mpMRI performance during readouts. CONCLUSION. Consistent, accurate, and reproducible reporting of prostate mpMRI is vital. Additionally, radiologists should be aware of common diagnostic pitfalls that can hinder mpMRI performance.

Multiparametric MRI for prostate cancer diagnosis: current status and future directions

The current diagnostic pathway for prostate cancer has resulted in overdiagnosis and consequent overtreatment as well as underdiagnosis and missed diagnoses in many men. Multiparametric MRI (mpMRI) of the prostate has been identified as a test that could mitigate these diagnostic errors. The performance of mpMRI can vary depending on the population being studied, the execution of the MRI itself, the experience of the radiologist, whether additional biomarkers are considered and whether mpMRI-targeted biopsy is carried out alone or in addition to systematic biopsy. A number of challenges to implementation remain, such as ensuring high-quality execution and reporting of mpMRI and ensuring that this diagnostic pathway is cost-effective. Nevertheless, emerging clinical trial data support the adoption of this technology as part of the standard of care for the diagnosis of prostate cancer.

Xanthogranulomatous prostatitis: A rare mimicker of prostate adenocarcinoma

Xanthogranulomatous prostatitis as mimicker of prostate adenocarcinoma can cause a diagnostic dilemma, as presented in this case. Therefore, alongside histopathology analysis, multiparametric magnetic resonance imaging (mpMRI) would be useful in this situation by identifying and characterizing suspicious prostatic lesions before biopsy thereby supporting current recommendations on the use of mpMRI.

Radiological semantics discriminate clinically significant grade prostate cancer

Background

Identification of imaging traits to discriminate clinically significant prostate cancer is challenging due to the multi focal nature of the disease. The difficulty in obtaining a consensus by the Prostate Imaging and Data Systems (PI-RADS) scores coupled with disagreements in interpreting multi-parametric Magnetic Resonance Imaging (mpMRI) has resulted in increased variability in reporting findings and evaluating the utility of this imaging modality in detecting clinically significant prostate cancer. This study assess the ability of radiological traits (semantics) observed on multi-parametric Magnetic Resonance images (mpMRI) to discriminate clinically significant prostate cancer.

Methods

We obtained multi-parametric MRI studies from 103 prostate cancer patients with 167 targeted biopsies from a single institution. The study was approved by our Institutional Review Board (IRB) for retrospective analysis. The biopsy location had been identified and marked by a clinical radiologist for targeted biopsy based on initial study interpretation. Using the target locations, two study radiologists independently re-evaluated the scans and scored 16 semantic traits on a point scale (up to 5 levels) based on mpMRI images. The semantic traits describe size, shape, and border characteristics of the prostate lesion, as well as presence of disease around lymph nodes (lymphadenopathy). We built a linear classifier model on these semantic traits and related to pathological outcome to identify clinically significant tumors (Gleason Score ≥ 7). The discriminatory ability of the predictors was tested using cross validation method randomly repeated and ensemble values were reported. We then compared the performance of semantic predictors with the PI-RADS predictors.

Results

We found several semantic features individually discriminated high grade Gleason score (ADC-intensity, Homogeneity, early-enhancement, T2-intensity and extraprostatic extention), these univariate predictors had an average area under the receiver operator characteristics (AUROC) ranging from 0.54 to 0.68. Multivariable semantic predictors with three features (ADC-intensity; T2-intensity, enhancement homogenicity) had an average AUROC of 0.7 [0.43, 0.94]. The PI-RADS based predictor had average AUROC of 0.6 [0.47, 0.75].

Conclusion

We find semantics traits are related to pathological findings with relatively higher reproducibility between radiologists. Multivariable predictors formed on these traits shows higher discriminatory ability compared to PI-RADS scores.

Compressed Central Zone Uptake on PSMA PET/CT-A Potential Pitfall in Interpretation

The case of a 66-year-old man undergoing a staging PSMA PET/CT after a recent diagnosis of prostate carcinoma is presented. In addition to uptake within the prostate consistent with primary tumor activity, mild symmetrical and diffuse uptake is also noted within central zone. The appearance is not consistent with likely tumor activity. Comparison is made with histopathology after a radical prostatectomy, and no correlating tumor is noted in the region of central zone uptake. Increased PSMA uptake within the compressed central zone of the prostate may represent a potential pitfall in PSMA PET/CT imaging.

Teardrop sign

We have submitted an interesting image of teardrop sign on prostate MRI.

Multiparametric MRI appearances of primary granulomatous prostatitis

OBJECTIVE

Radiological features of granulomatous prostatitis (GP) overlap with those of prostate adenocarcinoma. Identification of specific GP features may aid diagnosis. We aimed to evaluate the multiparametric MRI (mpMRI) features of GP.

METHODS

We retrospectively reviewed 16 patients from a cohort undergoing mpMRI and transperineal sector-guided prostate biopsies between July 2012 and May 2017. Images were analysed for lesion location, shape, size, extracapsular extension, signal intensity (SI), apparent diffusion coefficient (ADC) values, dynamic contrast enhancement (DCE) pattern and PI-RADS (Prostate Imaging - Reporting and Data System) v2 score.

RESULTS

Histology revealed 13 cases of nonspecific GP and 3 cases of xanthogranulomatous prostatitis. GP lesions were diffuse involving > 50% of the prostate ( n = 13) or nodular ( n = 3). Signal intensity on T ₂ weighted imaging was low and high on diffusion-weighted imaging. ADC values were low (mean 702 ± 79 × 10^-6 mm/s² ). Five patients had DCE imaging with all cases 'positive' as per PI-RADS scoring, with two cases displaying further ring enhancement consistent with abscess formation. Overall PI-RADS score for all cases was 5, indicating high suspicion of prostate cancer.

CONCLUSION

GP is difficult to differentiate from prostate cancer, but typically gives diffuse changes involving > 50% of the gland on mpMRI, with extracapsular extension and rim-enhancing areas. It should be considered a differential diagnosis in patients with recent urinary tract infection (UTI) or prior Bacillus Calmette-Guerin (BCG) treatment.

ADVANCES IN KNOWLEDGE

Prostate MRI imaging features including diffuse changes, extracapsular extension and rim-enhancing areas, in patients with recent UTI or BCG treatment may help identify granulomatous prostatitis cases.

[Imaging for initial diagnosis of localized prostate cancer]

The initial diagnosis of prostate cancer has been traditionally performed using systematic core biopsies with the use of magnetic resonance imaging (MRI) reserved to problem-solving scenarios. There is currently an ongoing paradigm shift towards the use of MRI prior to targeted biopsy as the standard approach. Prostate cancer therefore does not remain the last solid tumor entity diagnosed by non-targeted techniques but joins other solid tumor entities for which targeted diagnostic approaches have existed for a while. However, the complexity of the background tissue signal in the prostate makes lesion detection challenging. This article will provide an overview of the components of multiparametric prostate MRI and their interpretation using structured interpretation according to the current PI-RADSv2 (Prostate Imaging Reporting and Data System version 2) guidelines and of novel ultrasound techniques for primary diagnosis.

False positives in PIRADS (V2) 3, 4, and 5 lesions: relationship with reader experience and zonal location

PURPOSE

To investigate the effect of reader experience and zonal location on the occurrence of false positives (FPs) in PIRADS (V2) 3, 4, and 5 lesions on multiparametric (MP)-MRI of the prostate.

MATERIALS AND METHODS

This retrospective study included 139 patients who had consecutively undergone an MP-MRI of the prostate in combination with a transrectal ultrasound MRI fusion-guided biopsy between 2014 and 2017. MRI exams were prospectively read by a group of inexperienced radiologists (cohort 1; 54 patients) and an experienced radiologist (cohort 2; 85 patients). Multivariable logistic regression analysis was performed to determine the association of experience of the radiologist and zonal location with a FP reading. FP rates were compared between readings by inexperienced and experienced radiologists according to zonal location, using Chi-square (χ²) tests.

RESULTS

A total of 168 lesions in 139 patients were detected. Median patient age was 68 years (Interquartile range (IQR) 62.5-73), and median PSA was 10.9 ng/mL (IQR 7.6-15.9) for the entire patient cohort. According to multivariable logistic regression, inexperience of the radiologist was significantly (P = 0.044, odds ratio 1.927, 95% confidence interval [CI] 1.017-3.651) and independently associated with a FP reading, while zonal location was not (P = 0.202, odds ratio 1.444, 95% CI 0.820-2.539). In the transition zone (TZ), the FP rate of the inexperienced radiologists 59% (17/29) was significantly higher (χ²P = 0.033) than that of the experienced radiologist 33% (13/40).

CONCLUSION

Inexperience of the radiologist is significantly and independently associated with a FP reading, while zonal location is not. Inexperienced radiologists have a significantly higher FP rate in the TZ.

68Ga-PSMA-11 PET/MR Detects Local Recurrence Occult on mpMRI in Prostate Cancer Patients After HIFU

High-intensity focused ultrasound (HIFU) is a promising new modality for the treatment of localized prostate cancer (PCa). Follow-up of patients is recommended with biopsies and multiparametric MRI (mpMRI). However, mpMRI in the postinterventional setting is often false-negative. It was our aim to investigate if the new tracer targeting the prostate-specific membrane antigen (⁶⁸Ga-PSMA-11) could be used to localize recurrent disease with PET/MR in patients with discrepant findings between mpMRI and template biopsies. Methods: Interim analysis was performed of the first 10 patients scanned between September 2016 and May 2018 with positive template biopsy and negative mpMRI after HIFU from an ongoing clinical trial (NCT02265159). All patients underwent ⁶⁸Ga-PSMA-11 PET/MRI within 3 mo. Four prostatic quadrants were defined, and for every quadrant suspicion for recurrence was rated on a 5-point Likert scale from definitely no recurrence (1) to highly suspected of recurrence (5), with 4 used as a cutoff for suspected disease based on PET/MRI by a masked reader. ⁶⁸Ga-PSMA-11 uptake of suspected lesions and background areas was measured with the SUV_max The apparent diffusion coefficient values of lesions and background were given for each segment. PET/MRI scans were compared with the template biopsy results, including corresponding Gleason scores (GS), number of positive cores, and tumor length. Results: The quadrant-based sensitivity, specificity, and positive and negative predictive values for PET/MRI were 55%, 100%, 100%, and 85%, respectively. Patient-based PET/MRI was negative in 4 cases with GS 3 + 4 and a tumor length between 0.1 and 3 mm. All tumor lesions with GS 4 + 3 or higher were detected on PET/MRI. Conclusion: Our preliminary results indicate that ⁶⁸Ga-PSMA-11-PET/MR has the potential to localize PCa recurrence after HIFU occult on mpMRI.

Infectious and Inflammatory Diseases of the Urinary Tract: Role of MR Imaging

Urinary tract infection (UTI) is among the most common of bacterial infections. Imaging studies are only required in cases of complicated UTIs. Ultrasound remains the first-line imaging method; however, CT is the gold standard for evaluation of UTIs. MR imaging's improved contrast resolution and absence of ionizing radiation may recommend its use for assessment of lower UTIs. Furthermore, MR imaging performs with diagnostic accuracy at least similar to CT in complicated UTIs, except for the identification of calculi and emphysematous pyelonephritis. In this article, the role of MR imaging for the evaluation of infectious and inflammatory disease processes of the urinary tract is reviewed.

Accuracy and Variability of Prostate Multiparametric Magnetic Resonance Imaging Interpretation Using the Prostate Imaging Reporting and Data System: A Blinded Comparison of Radiologists

BACKGROUND

Multiparametric (mp) magnetic resonance imaging (MRI) has become an important tool for the detection of clinically significant prostate cancer. However, diagnostic accuracy is affected by variability between radiologists.

OBJECTIVE

To determine the accuracy and variability in prostate mpMRI interpretation among radiologists, both individually and in teams, in a blinded fashion.

DESIGN, SETTING, AND PARTICIPANTS

A study cohort (n=32) was created from our prospective registry of patients who received prostate mpMRI with subsequent biopsy. The cohort was then independently reviewed by four radiologists of varying levels of experience, who assigned a Prostate Imaging Reporting and Data System (PI-RADS) classification, blinded to all clinical information. Consensus interpretation by teams of two radiologists was evaluated after a 12-wk wash-out period. Interpretive accuracy was calculated with various cutoffs for PI-RADS classification and Gleason score. Variability among individual radiologists and teams was calculated using the Fleiss kappa and intraclass correlation coefficient (ICC).

RESULTS AND LIMITATIONS

Using PI-RADS 3+/Gleason 7+ (p<0.01) and PI-RADS 4+/Gleason 6+ (p=0.02) as cutoffs, significant differences in accuracy among the four radiologists were noted. At no cutoff for PI-RADS classification or Gleason score did a team read achieve higher accuracy than the most accurate radiologist. The kappa and ICC ranged from 0.22 to 0.29 for the individuals and from 0.16 to 0.21 for the teams (poor agreement). A larger sample size may be needed to adequately power differences in accuracy among individual radiologists.

CONCLUSIONS

At various cutoffs for PI-RADS classification and Gleason score, we find significant differences in individual radiologist accuracy, as well as a poor agreement among individual radiologists. Consensus interpretations-as teams of two radiologists-did not improve accuracy or reduce variability.

PATIENT SUMMARY

This study investigated radiologist variability and differences in accuracy using multiparametric magnetic resonance imaging for the diagnosis of prostate cancer. Despite attempts to standardize interpretation within the field, we found substantial variability and significant differences in accuracy among individual radiologists.

Retrospective Study of the Significant Predictive Role of Inflammatory Degree in Initial and Repeat Prostate Biopsy Specimens for Detecting Prostate Cancer

Purpose

The purpose of this study was to determine whether histologic inflammation (HI) in initial and repeat prostate biopsy specimens was significantly associated with the detection of prostate cancer.

Materials and Methods

Between 2005 and 2017, the clinicopathological records of patients with high prostatespecific antigen (PSA) levels who underwent initial and repeat prostate biopsies were retrospectively reviewed. The presence of HI and its degree in each biopsied specimen were interpreted by one uropathologist with 20 years of experience. The association between HI and cancer diagnosis was statistically assessed, with p < 0.05 considered significant, and the cancer and non-cancer groups were compared.

Results

Among the 522 patients with a median PSA levels of 6.5 ng/dL, including 258 (49.4%) whose cancer was diagnosed following repeat biopsy, the median degrees of HI in the initial and repeat biopsies were 25.0% and 41.7%, respectively. Furthermore, 211 (40.4%) and 247 (47.3%) patients had HI (> 0%) on biopsied specimens, respectively. Comparison of the cancer and noncancer groups revealed that a greater rate of HI specimens in the initial biopsy was associated with fewer prostate cancer diagnoses following repeat biopsy (p < 0.001). Other comparisons between the cancer and non-cancer groups showed that the cancer group had a significantly higher rate of hypertension, whereas those non-cancer group had a significantly higher rate of benign prostatic hyperplasia and prostatitis (p < 0.05).

Conclusion

A finding of a lesser degree of HI in the initial and a greater degree of HI in the repeat biopsied specimens was associated with the higher probability of cancer diagnosis in patients with high PSA levels.

Towards a universal MRI atlas of the prostate and prostate zones : Comparison of MRI vendor and image acquisition parameters

BACKGROUND AND PURPOSE

The aim of this study was to evaluate an automatic multi-atlas-based segmentation method for generating prostate, peripheral (PZ), and transition zone (TZ) contours on MRIs with and without fat saturation (±FS), and compare MRIs from different vendor MRI systems.

METHODS

T2-weighted (T2) and fat-saturated (T2FS) MRIs were acquired on 3T GE (GE, Waukesha, WI, USA) and Siemens (Erlangen, Germany) systems. Manual prostate and PZ contours were used to create atlas libraries. As a test MRI is entered, the procedure for atlas segmentation automatically identifies the atlas subjects that best match the test subject, followed by a normalized intensity-based free-form deformable registration. The contours are transformed to the test subject, and Dice similarity coefficients (DSC) and Hausdorff distances between atlas-generated and manual contours were used to assess performance.

RESULTS

Three atlases were generated based on GE_T2 (n = 30), GE_T2FS (n = 30), and Siem_T2FS (n = 31). When test images matched the contrast and vendor of the atlas, DSCs of 0.81 and 0.83 for T2 ± FS were obtained (baseline performance). Atlases performed with higher accuracy when segmenting (i) T2FS vs. T2 images, likely due to a superior contrast between prostate vs. surrounding tissue; (ii) prostate vs. zonal anatomy; (iii) in the mid-gland vs. base and apex. Atlases performance declined when tested with images with differing contrast and MRI vendor. Conversely, combined atlases showed similar performance to baseline.

CONCLUSION

The MRI atlas-based segmentation method achieved good results for prostate, PZ, and TZ compared to expert contoured volumes. Combined atlases performed similarly to matching atlas and scan type. The technique is fast, fully automatic, and implemented on commercially available clinical platform.

Pretreatment multiparametric MRI is independently associated with biochemical outcome in men treated with radiation therapy for prostate cancer

PURPOSE

The purpose of this study was to investigate the utility of pre-treatment multiparametric magnetic resonance imaging (mpMRI) in a modern cohort of intermediate and high-risk prostate cancer patients treated with primary radiotherapy.

METHODS AND MATERIALS

One hundred twenty three men with National Comprehensive Cancer Network (NCCN) intermediate or high-risk prostate cancer were treated with primary EBRT and/or brachytherapy and had evaluable pre-treatment mpMRI with endorectal coil. Images were assessed for the presence of radiographic extraprostatic extension (rEPE), seminal vesicle invasion (rSVI), lymph node involvement (LNI), sextant involvement, and largest axial tumor diameter. Imaging characteristics were analyzed along with clinical risk factors against freedom from biochemical failure (FFBF). Median follow-up time was 50 months.

RESULTS

Fourteen (11%) men developed biochemical failure. The 5-year FFBF was 94% in intermediate-risk patients and 82% in high-risk patients (p < 0.01). mpMRI findings including rEPE (29% vs. 66%, p < 0.01), rSVI (6% vs. 25%, p < 0.01), LNI (1% vs. 30%, p < 0.01), and largest axial tumor size> 15 mm (27% vs. 48%, p = 0.02) were identified in men with intermediate vs. high risk prostate cancer, respectively. mpMRI features associated with 5-y FFBF biochemical failure on univariate analysis included rEPE (80% vs 98%), rSVI (55% vs. 96%), LNI (65% vs. 93%), and largest axial tumor size >15mm (81% vs. 94%, all p < 0.01). Men without any high risk MRI finding had a 5-y FFBF of 100% vs. 81% (p < 0.01). Adverse imaging features (HR 8.9, p < 0.01) were independently associated with biochemical failure in a bivariate model analyzed alongside clinical risk category (HR 3.2, p = 0.04).

CONCLUSIONS

Pre-treatment mpMRI findings are strongly associated with biochemical outcomes in a modern cohort of intermediate and high-risk patients treated with primary radiotherapy. mpMRI may aid risk stratification beyond clinical risk factors in men treated with radiation therapy; further study is warranted to better understand how mpMRI can be used to individualize therapy.