The incremental value of contrast-enhanced MRI in the detection of biopsy-proven local recurrence of prostate cancer after radical prostatectomy: effect of reader experience

Biparametric MRI in prostate cancer during active surveillance: is it safe?

Active surveillance (AS) is the preferred option for patients presenting with low-intermediate-risk prostate cancer. MRI now plays a crucial role for baseline assessment and ongoing monitoring of AS. The Prostate Cancer Radiological Estimation of Change in Sequential Evaluation (PRECISE) recommendations aid radiological assessment of progression; however, current guidelines do not advise on MRI protocols nor on frequency. Biparametric (bp) imaging without contrast administration offers advantages such as reduced costs and increased throughput, with similar outcomes to multiparametric (mp) MRI shown in the biopsy naïve setting. In AS follow-up, the paradigm shifts from MRI lesion detection to assessment of progression, and patients have the further safety net of continuing clinical surveillance. As such, bpMRI may be appropriate in clinically stable patients on routine AS follow-up pathways; however, there is currently limited published evidence for this approach. It should be noted that mpMRI may be mandated in certain patients and potentially offers additional advantages, including improving image quality, new lesion detection, and staging accuracy. Recently developed AI solutions have enabled higher quality and faster scanning protocols, which may help mitigate against disadvantages of bpMRI. In this article, we explore the current role of MRI in AS and address the need for contrast-enhanced sequences. CLINICAL RELEVANCE STATEMENT: Active surveillance is the preferred plan for patients with lower-risk prostate cancer, and MRI plays a crucial role in patient selection and monitoring; however, current guidelines do not currently recommend how or when to perform MRI in follow-up. KEY POINTS: Noncontrast biparametric MRI has reduced costs and increased throughput and may be appropriate for monitoring stable patients. Multiparametric MRI may be mandated in certain patients, and contrast potentially offers additional advantages. AI solutions enable higher quality, faster scanning protocols, and could mitigate the disadvantages of biparametric imaging.

Prostate Imaging for Local Recurrence Reporting and Data System for Biparametric Magnetic Resonance Imaging: A Proposal

We investigated a novel dedicated Prostate Imaging for Local Recurrence Reporting and Data System (PI-RRADS) in biochemical recurrence after radiotherapy (RT) and rad- ical prostatectomy (RP) evaluating biparametric magnetic resonance imaging (bpMRI) exams, at 3T MRI of 55 patients. Associating bpMRI and biochemical recurrence data, we calculated bpMRI diagnostic accuracy. Four probability categories, from 1 (very low) to 4 (very high), were distinguished. In 20 patients with radiotherapy, 25% and 75% of lesions were reported as PI-RRADS 3, and 4, respectively. In 35 patients with radi- cal prostatectomy, 7.7% of lesions were included in PI-RRADS 1-2, whereas 40.4% and 51.9% in PI-RRADS 3 and 4 categories, respectively. Excellent agreement and significant correlation between bpMRI and biochemical recurrence were found. BpMRI showed sensitivity, specificity, positive predictive value, negative predictive value, false-posi- tive value, false-negative value, and total diagnostic accuracy of 96.15%, 86.7%, 97.4 %, 81.25%, 13.3%, 3.8% and 94.6%, respectively. BpMRI-based PI-RRADS allows the detection and localization local recurrence in biochemical recurrence after RT and RP contributing in clinical management and treatment.

Effects of dynamic contrast enhancement on transition zone prostate cancer in Prostate Imaging Reporting and Data System Version 2.1

BACKGROUND

The aim of the study was to analyse the effects of dynamic contrast enhanced (DCE)-MRI on transitional-zone prostate cancer (tzPCa) and clinically significant transitional-zone prostate cancer (cs-tzPCa) in Prostate Imaging Reporting and Data System (PI-RADS) Version 2.1.

PATIENTS AND METHODS

The diagnostic efficiencies of T2-weighted imaging (T2WI) + diffusion-weighted imaging (DWI), T2WI + dynamic contrast-enhancement (DCE), and T2WI + DWI + DCE in tzPCa and cs-tzPCa were compared using the score of ≥ 4 as the positive threshold and prostate biopsy as the reference standard.

RESULTS

A total of 425 prostate cases were included in the study: 203 cases in the tzPCa group, and 146 in the cs-tzPCa group. The three sequence combinations had the similar areas under the curves in diagnosing tzPCa and cs-tzPCa (all P < 0.05). The sensitivity of T2WI + DCE and T2WI + DWI + DCE (84.7% and 85.7% for tzPCa; 88.4% and 89.7% for cs-tzPCa, respectively) in diagnosing tzPCa and cs-tzPCa was significantly greater than that of T2WI + DWI (79.3% for tzPCa; 82.9% for cs-tzPCa). The specificity of T2WI + DWI (86.5% for tzPCa; 74.9% for cs-tzPCa) were significantly greater than those of T2WI + DCE and T2WI + DWI + DCE (68.0% and 68.5% for tzPCa; 59.1% and 59.5% for cs-tzPCa, respectively) (all P > 0.05). The diagnostic efficacies of T2WI + DCE and T2WI + DWI + DCE had no significant differences (all P < 0.05).

CONCLUSIONS

DCE can improve the sensitivity of diagnosis for tzPCa and cs-tzPCa, and it is useful for small PCa lesion diagnosis.

Mapping of Local Recurrences After Radical Prostatectomy Using 68-Gallium-Prostate-Specific Membrane Antigen Positron Emission Tomography/Computed Tomography: Implications for Postprostatectomy Radiation Therapy Clinical Target Volumes

PURPOSE

Our objective is to describe the distribution of local recurrences after radical prostatectomy (RP) as delineated using 68-Gallium-prostate-specific membrane antigen positron emission tomography/computed tomography (⁶⁸Ga-PSMA PET/CT) to identify areas where current consensus guideline clinical target volumes (CTVs) are insufficient or excessive and to identify predictors of recurrence location within the fossa.

METHODS AND MATERIALS

Retrospective review of databases from 2 tertiary referral centers was performed to identify patients who underwent ⁶⁸Ga-PSMA PET/CT for biochemical recurrence after RP. Those with a component of local recurrence were included for further analysis. The epicenter of each recurrence was defined relative to reference points in 3 axes, categorized into 1 of 7 levels in the superior/inferior axis relative to the vesicourethral anastomosis, and recorded as within or outside the Faculty of Radiation Oncology Genito-urinary Group (FROGG) and Radiation Therapy Oncology Group consensus CTVs. Univariate and multivariate analysis was performed to identify predictors of recurrence location based on clinical and histopathologic variables.

RESULTS

One thousand forty-nine ⁶⁸Ga-PSMA PET/CT scans were reviewed. One hundred forty sites of local recurrence were identified on 132 scans. Relative to the vesicourethral anastomosis, 13 (9%), 31 (22%), 17 (12%), 24 (17%), 27 (19%), 20 (14%), and 8 (6%) recurrences occurred >5 mm inferior; within 5 mm above or below; and 6 to 15 mm, 16 to 25 mm, 26 to 35 mm, 36 to 45 mm, and >45 mm superiorly, respectively. Thirteen (9%) and 2 (1.4%) recurrences occurred beyond the FROGG and Radiation Therapy Oncology Group consensus CTVs, respectively, with all below the inferior CTV margin.

CONCLUSIONS

In the largest study to date mapping local recurrences after RP in 3-dimensions, we provide several insights to inform future contouring guidelines; in particular, 9% of recurrences occurred inferior to the FROGG CTV.

Quality checkpoints in the MRI-directed prostate cancer diagnostic pathway

Multiparametric MRI of the prostate is now recommended as the initial diagnostic test for men presenting with suspected prostate cancer, with a negative MRI enabling safe avoidance of biopsy and a positive result enabling MRI-directed sampling of lesions. The diagnostic pathway consists of several steps, from initial patient presentation and preparation to performing and interpreting MRI, communicating the imaging findings, outlining the prostate and intra-prostatic target lesions, performing the biopsy and assessing the cores. Each component of this pathway requires experienced clinicians, optimized equipment, good inter-disciplinary communication between specialists, and standardized workflows in order to achieve the expected outcomes. Assessment of quality and mitigation measures are essential for the success of the MRI-directed prostate cancer diagnostic pathway. Quality assurance processes including Prostate Imaging-Reporting and Data System, template biopsy, and pathology guidelines help to minimize variation and ensure optimization of the diagnostic pathway. Quality control systems including the Prostate Imaging Quality scoring system, patient-level outcomes (such as Prostate Imaging-Reporting and Data System MRI score assignment and cancer detection rates), multidisciplinary meeting review and audits might also be used to provide consistency of outcomes and ensure that all the benefits of the MRI-directed pathway are achieved.

Prostate MRI Qualification: AJR Expert Panel Narrative Review

Prostate MRI is now established as a first-line investigation for individuals presenting with suspected localized or locally advanced prostate cancer. Successful delivery of the MRI-directed pathway for prostate cancer diagnosis relies on high-quality imaging as well as the interpreting radiologist's experience and expertise. Radiologist certification in prostate MRI may help limit interreader variability, optimize outcomes, and provide individual radiologists with documentation of meeting predefined standards. This AJR Expert Panel Narrative Review summarizes existing certification proposals, recognizing variable progress across regions in establishing prostate MRI certification programs. To our knowledge, Germany is the only country with a prostate MRI certification process that is currently available for radiologists. However, prostate MRI certification programs have also recently been proposed in the United States and United Kingdom and by European professional society consensus panels. Recommended qualification processes entail a multifaceted approach, incorporating components such as minimum case numbers, peer learning, course participation, continuing medical education credits, and feedback from pathology results. Given the diversity in health care systems, including in the provision and availability of MRI services, national organizations will likely need to take independent approaches to certification and accreditation. The relevant professional organizations should begin developing these programs or continue existing plans for implementation.

The role of multiparametric mri in the diagnosis of local recurrence after radical prostatectomy and before salvage radiotherapy

PURPOSE

Assess multiparametric-MRI (mp-MRI) diagnostic accuracy in the detection of local recurrence of Prostate Cancer (PCa) after Radical Prostatectomy (PR) and before Radiation Therapy (RT).

MATERIALS AND METHODS

A total of 188 patients underwent 1.5-T mp-MRI after RP before RT. Patients were divided into two groups: with biochemical recurrence (group A) and without but with high risk of local recurrence (group B). Continuous variables were compared between two groups using T-Student; categoric variables were analyzed using Pearson chi-square. ROC analysis was performed considering PSA before RT, ISUP, pT and pN as grouping variables.

RESULTS

PCa recurrence (reduction of PSA levels after RT) was 89.8% in the group A and 80.3% in the group B. Comparing patients with and without PCa recurrence, there was a significant difference in PSA values before RT for group A and for PSA values before RT and after RT for group B. In group A, there was a significant correlation between PSA before RT and diameter of recurrence and between PSA before RT and time spent before recurrence. The mp-MRI diagnostic accuracy in detecting PCa local recurrence after RP is of 62.2% in group A and 38% in group B. DWI is the most specific MRI-sequence and DCE the most sensitive. For PSA = 0.5 ng/ml, the AUC decreases while sensitivity and accuracy increase for each MRI-sequence. For PSA = 0.9 ng/ml, DCE-AUC increases significantly.

CONCLUSION

mp-MRI should always be performed before RT when a recurrence is suspected. New scenarios can be opened considering the role of DWI for PSA ≤ 0.5 ng/ml.

Current Status of Biparametric MRI in Prostate Cancer Diagnosis: Literature Analysis

The role of multiparametric MRI (mpMRI) in the detection of prostate cancer is well-established. Based on the limited role of dynamic contrast enhancement (DCE) in PI-RADS v2.1, the risk of potential side effects, and the increased cost and time, there has been an increase in studies advocating for the omission of DCE from MRI assessments. Per PI-RADS v2.1, DCE is indicated in the assessment of PI-RADS 3 lesions in the peripheral zone, with its most pronounced effect when T2WI and DWI are of insufficient quality. The aim of this study was to evaluate the methodology and reporting in the literature from the past 5 years regarding the use of DCE in prostate MRI, especially with respect to the indications for DCE as stated in PI-RADS v2.1, and to describe the different approaches used across the studies. We searched for studies investigating the use of bpMRI and/or mpMRI in the detection of clinically significant prostate cancer between January 2017 and April 2022 in the PubMed, Web of Science, and Google Scholar databases. Through the search process, a total of 269 studies were gathered and 41 remained after abstract and full-text screening. The following information was extracted from the eligible studies: general clinical and technical characteristics of the studies, the number of PI-RADS 3 lesions, different definitions of clinically significant prostate cancer (csPCa), biopsy thresholds, reference standard methods, and number and experience of readers. Forty-one studies were included in the study. Only 51% (21/41) of studies reported the prevalence of csPCa in their equivocal lesion (PI-RADS category 3 lesions) subgroups. Of the included studies, none (0/41) performed a stratified sub-analysis of the DCE benefit versus MRI quality and 46% (19/41) made explicit statements about removing MRI scans based on a range of factors including motion, noise, and image artifacts. Furthermore, the number of studies investigating the role of DCE using readers with varying experience was relatively low. This review demonstrates that a high proportion of the studies investigating whether bpMRI can replace mpMRI did not transparently report information inherent to their study design concerning the key indications of DCE, such as the number of clinically insignificant/significant PI-RADS 3 lesions, nor did they provide any sub-analyses to test image quality, with some removing bad quality MRI scans altogether, or reader-experience-dependency indications for DCE. For the studies that reported on most of the DCE indications, their conclusions about the utility of DCE were heavily definition-dependent (with varying definitions of csPCa and of the PI-RADS category biopsy significance threshold). Reporting the information inherent to the study design and related to the specific indications for DCE as stated in PI-RADS v2.1 is needed to determine whether DCE is helpful or not. With most of the recent literature being retrospective and not including the data related to DCE indications in particular, the ongoing dispute between bpMRI and mpMRI is likely to linger.

Radiologists and Clinical Trials: Part 1 The Truth About Reader Disagreements

The debate over human visual perception and how medical images should be interpreted have persisted since X-rays were the only imaging technique available. Concerns over rates of disagreement between expert image readers are associated with much of the clinical research and at times driven by the belief that any image endpoint variability is problematic. The deeper understanding of the reasons, value, and risk of disagreement are somewhat siloed, leading, at times, to costly and risky approaches, especially in clinical trials. Although artificial intelligence promises some relief from mistakes, its routine application for assessing tumors within cancer trials is still an aspiration. Our consortium of international experts in medical imaging for drug development research, the Pharma Imaging Network for Therapeutics and Diagnostics (PINTAD), tapped the collective knowledge of its members to ground expectations, summarize common reasons for reader discordance, identify what factors can be controlled and which actions are likely to be effective in reducing discordance. Reinforced by an exhaustive literature review, our work defines the forces that shape reader variability. This review article aims to produce a singular authoritative resource outlining reader performance's practical realities within cancer trials, whether they occur within a clinical or an independent central review.

Response on DCE-MRI predicts outcome of salvage radiotherapy for local recurrence after radical prostatectomy

OBJECTIVE

To assess the predictive role of response on dynamic contrast enhancement on magnetic resonance imaging (DCE-MRI) of visible local lesions in the setting of salvage radiotherapy (sRT) after radical prostatectomy.

METHODS

All patients referred for sRT for biochemical failure after radical prostatectomy from February 2014 to September 2016 were considered eligible if they had been restaged with DCE-MRI and had been found to have a visible lesion in the prostatic bed, but no distant/nodal disease on choline positron emission tomography (PET)-computed tomography (CT). Eligible patients were contacted during follow-up and offered reimaging with serial DCE-MRI until lesion resolution. Complete response (CR) was defined as the disappearance of the target lesion on DCE-MRI; prostate-specific antigen (PSA) recurrence was defined as a 0.2 ng/mL PSA rise above the nadir. Median follow-up after sRT was 41.5 months (range, 12.1-61.2 months).

RESULTS

Fifty-nine patients agreed to undergo repeated DCE-MRI for a total of 64 studied lesions. Overall, 57 lesions (89.1%) showed a CR after 1 (51 patients) or 2 (6 patients) scans, while 7 lesions did not show any change (no response [NR]). At 42 months, no evidence of biochemical disease (bNED) survival was 74.7±6.4% and 64.3±21.0% for patients with CR and NR lesions, respectively (hazard ratio [HR], 3.181; 95% confidence interval [CI], 0.157-64.364; p = 0.451). When only patients treated with sRT without androgen deprivation were selected (n = 41), bNED survival rates at 42 months were 72.1±8.0% and 0, respectively (HR, 52.830; 95% CI, 1.893-1474.110; p = 0.020).

CONCLUSIONS

Patients whose lesions disappear during follow-up have a better outcome than those with unchanged lesions after sRT alone.

Diagnostic accuracy of biparametric versus multiparametric prostate MRI: assessment of contrast benefit in clinical practice

PURPOSE

To assess the added value of dynamic contrast-enhanced (DCE) in prostate MR in clinical practice.

METHODS

Two hundred sixty-four patients underwent prostate MRI, with T2 and DWI sequences initially interpreted, prior to full multiparametric magnetic resonance imaging (mpMRI) interpretation using a Likert 1-5 scale. A prospective opinion was given on likely benefit of contrast prior to review of the DCE sequence, and retrospectively following full mpMRI review. The final histology result following targeted and/or systematic biopsy of the prostate was used for outcome purposes.

RESULTS

Biparametric magnetic resonance imaging (bpMRI) and mpMRI were assigned the same score in 86% of cases; when dichotomising to a negative or positive MRI (Likert score ≥ 3), concordance increased to 92.8%. At Likert score ≥ 3 bpMRI detected 89.9% of all cancers and 93.5% clinically significant prostate cancers (csPCa) and mpMRI 90.7% and 94.6%, respectively. mpMRI had fewer false positives than bpMRI (11.4% vs 18.9%) and a lower Likert 3 rate (8.3% vs 17%), conferring higher specificity (74% vs 67%), but similar sensitivity (95% versus 94%) and ROC-AUC (90% vs 89%). At a positive MRI threshold of Likert ≥ 4, mpMRI had a higher sensitivity than bpMRI (89% versus 80%) and detected more csPCa (89.2% versus 79.6%). DCE was prospectively considered of potential benefit in 27.3%, but readers would only recall 11% of patients for DCE sequences, mainly to assess score 3 peripheral zone lesions. Following full mpMRI review, DCE was considered helpful in 28.4% of cases; in 23/75 (30.6%) of these cases this only became apparent after reviewing the sequence, reasons included increased confidence, presence of "safety-net" lesions or inflammatory lesions.

CONCLUSION

BpMRI has equivalent cancer detection rates to mpMRI; however, mpMRI had fewer Likert 3 call rates and increased specificity and was subjectively considered of benefit by readers in 28.4% of cases.

KEY POINTS

• bpMRI has similar cancer detection rates to the full mpMRI protocol at a positive MRI threshold of Likert 3. • mpMRI had fewer intermediate category 3 calls (8.3%) than bpMRI (17%) and fewer false positives than bpMRI (11.4% vs 18.9%), conferring higher specificity (74% vs 67%). • Readers considered DCE beneficial in 28.4% of cases, but in a relatively high number (30.6%) this only became apparent after reviewing the sequence.

Magnetic Resonance Imaging Assessment After Therapy in Prostate Cancer

Prostate cancer is the fifth leading cause of death worldwide. A variety of treatment options is available for localized prostate cancer and may range from active surveillance to focal therapy or whole gland treatment, that is, surgery or radiotherapy. Serum prostate-specific antigen levels are an important tool to monitor treatment success after whole gland treatment, unfortunately prostate-specific antigen is unreliable after focal therapy. Multiparametric magnetic resonance imaging of the prostate is rapidly gaining field in the management of prostate cancer and may play a crucial role in the evaluation of recurrent prostate cancer. This article will focus on postprocedural magnetic resonance imaging after different forms of local therapy in patients with prostate cancer.

PI-RADS version 2.1: one small step for prostate MRI

Multiparametric (mp) prostate magnetic resonance imaging (MRI) is playing an increasingly prominent role in the diagnostic work-up of patients with suspected prostate cancer. Performing mpMRI before biopsy offers several advantages including biopsy avoidance under certain clinical circumstances and targeting biopsy of suspicious lesions to enable the correct diagnosis. The success of the technique is heavily dependent on high-quality image acquisition, interpretation, and report communication, all areas addressed by previous versions of the Prostate Imaging-Reporting and Data System (PI-RADS) recommendations. Numerous studies have validated the approach, but the widespread adoption of PI-RADS version 2 has also highlighted inconsistencies and limitations, particularly relating to interobserver variability for evaluation of the transition zone. These limitations are addressed in the recently released version 2.1. In this article, we highlight the key changes proposed in PI-RADS v2.1 and explore the background reasoning and evidence for the recommendations.

Functional Magnetic Resonance Imaging in the Diagnosis of Locally Recurrent Prostate Cancer: Are All Pulse Sequences Helpful?

Objective

To perform a meta-analysis to quantitatively assess functional magnetic resonance imaging (MRI) in the diagnosis of locally recurrent prostate cancer.

Materials and Methods

A comprehensive search of the PubMed, Embase, Cochrane Central Register of Controlled Trials, and Cochrane Database of Systematic Reviews was conducted from January 1, 1995 to December 31, 2016. Diagnostic accuracy was quantitatively pooled for all studies by using hierarchical logistic regression modeling, including bivariate modeling and hierarchical summary receiver operating characteristic (HSROC) curves (AUCs). The Z test was used to determine whether adding functional MRI to T2-weighted imaging (T2WI) results in significantly increased diagnostic sensitivity and specificity.

Results

Meta-analysis of 13 studies involving 826 patients who underwent radical prostatectomy showed a pooled sensitivity and specificity of 91%, and the AUC was 0.96. Meta-analysis of 7 studies involving 329 patients who underwent radiotherapy showed a pooled sensitivity of 80% and specificity of 81%, and the AUC was 0.88. Meta-analysis of 11 studies reporting 1669 sextant biopsies from patients who underwent radiotherapy showed a pooled sensitivity of 54% and specificity of 91%, and the AUC was 0.85. Sensitivity after radiotherapy was significantly higher when diffusion-weighted MRI data were combined with T2WI than when only T2WI results were used. This was true when meta-analysis was performed on a per-patient basis (p = 0.027) or per sextant biopsy (p = 0.046). A similar result was found when ¹H-magnetic resonance spectroscopy (¹H-MRS) data were combined with T2WI and sextant biopsy was the unit of analysis (p = 0.036).

Conclusion

Functional MRI data may not strengthen the ability of T2WI to detect locally recurrent prostate cancer in patients who have undergone radical prostatectomy. By contrast, diffusion-weight MRI and ¹H-MRS data may improve the sensitivity of T2WI for patients who have undergone radiotherapy.

Innovations in imaging modalities for recurrent and metastatic prostate cancer: a systematic review

INTRODUCTION

The last decade has witnessed tremendous changes in the management of advanced and metastatic castration resistant prostate cancer. In the current systematic review, we analyze novel imaging techniques in the setting of recurrent and metastatic prostate cancer (PCa), exploring available data and highlighting future exams which could enter clinical practice in the upcoming years.

EVIDENCE ACQUISITION

The National Library of Medicine Database was searched for relevant articles published between January 2012 and August 2017. A wide search was performed including the combination of following words: "Prostate" AND "Cancer" AND ("Metastatic" OR "Recurrent") AND "imaging" AND ("MRI" OR "PET"). The selection procedure followed the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) principles and is presented using a PRISMA flow chart.

EVIDENCE SYNTHESIS

Novel imaging techniques, as multiparametric magnetic resonance imaging (MRI), whole-body MRI and Choline and prostate-specific membrane antigen (PSMA) PET imaging techniques are currently revolutioning the treatment planning in patients with advanced and metastatic PCa, allowing a better characterization of the disease. Multiparametric MRI performs well in the detection of local recurrences, with sensitivity rates of 67-98% and overall diagnostic accuracy of 83-93%, depending on the type of magnetic field strength (1.5 vs. 3T). Whole body MRI instead shows a high specificity (>95%) for bone metastases. PET imaging, and in particular PSMA PET/CT, showed promising results in the detection of both local and distant recurrences, even for low PSA values (<0.5 ng/mL). Sensitivity varies from 77-98% depending on PSA value and PSA velocity.

CONCLUSIONS

Whole body-MRI, NaF PET, Choline-PET/CT and PSMA PET/CT are flourishing techniques which find great application in the field of recurrent and metastatic PCa, in the effort to reduce treatment of "PSA only" and rather focus our therapies on clinical tumor entities. Standardization is urgently needed to allow adequate comparison of results and diffusion on a large scale.

Prostate MR Imaging for Posttreatment Evaluation and Recurrence

Prostate multiparametric MR imaging (mpMRI) plays an important role in local evaluation after treatment of prostate cancer. After radical prostatectomy, radiation therapy, and focal therapy, mpMRI can be used to visualize normal post-treatment changes and to diagnose locally recurrent disease. An understanding of the various treatments and expected changes is essential for complete and accurate post-treatment mpMRI interpretation.

Imaging for the Detection of Locoregional Recurrences in Biochemical Progression After Radical Prostatectomy-A Systematic Review

CONTEXT

Local and regional recurrence after radical prostatectomy (RP) can be treated using salvage radiotherapy (SRT). If the recurrence can be delineated on diagnostic imaging, this could allow for increasingly individualized SRT.

OBJECTIVE

This systematic review aimed at evaluating the evidence regarding the usefulness of positron emission tomography (PET) and magnetic resonance imaging (MRI) in identifying local and regional recurrences, with the aim to further individualize the SRT treatment.

EVIDENCE ACQUISITION

A systematic PubMed/Medline search was conducted in December 2015. Studies included were imaging studies of post-RP patients focusing on local and/or regional recurrence where sensitivity and specificity of MRI or PET were the primary end points. Only studies using biopsy, other histological analysis, and/or treatment follow-up as reference standard were included. Quality Assessment of Diagnostic Accuracy Studies-2 was used to score the study quality. Twenty-five articles were deemed of sufficient quality and included in the review.

EVIDENCE SYNTHESIS

[¹¹C]Acetate had the highest pooled sensitivity (92%), while [¹¹C]choline and [¹⁸F]choline had pooled sensitivities of 71% and 84%, respectively. The PET tracer with highest pooled specificity was [¹¹C]choline (86%). Regarding MRI, MR spectroscopy combined with dynamic contrast enhanced (DCE) MRI showed the highest pooled sensitivity (89%). High pooled sensitivities were also seen using multiparametric MRI (84%), diffusion-weighted MRI combined with T2-weigthed (T2w) imaging (82%), and DCE MRI combined with T2w imaging (82%). These also showed high pooled specificities (85%, 89%, and 92%, respectively).

CONCLUSIONS

Both MRI and PET have adequate sensitivity and specificity for the detection of prostate cancer recurrences post-RP. Multiparametric MRI, using diffusion-weighted and/or DCE imaging, and the choline-labeled tracers showed high pooled sensitivity and specificity, although their ranges were broad.

PATIENT SUMMARY

After reviewing imaging studies of recurrent prostate cancer after prostatectomy, we concluded that choline positron emission tomography and diffusion-weighted magnetic resonance imaging can be proposed as the current standard, with high sensitivity and specificity.

The value of adding diffusion-weighted images for tumor detection and preoperative staging in renal pelvic carcinoma for the reader's experience

PURPOSE

This retrospective study aimed to assess the value of adding diffusion-weighted magnetic resonance imaging (DWI) or gadolinium-enhanced fat-suppressed T1WI (CEI) to T2-weighted imaging (T2WI) for preoperative T categorization in renal pelvic carcinoma by the reader's experience using surgical specimens as the reference standard.

METHODS

Two radiologists (Reader 1; 3 years, 2; 13 years) reviewed 49 cases with urothelial carcinoma who underwent magnetic resonance imaging examination before surgery, independently, using three image sets: T2WI alone, T2WI plus DWI, and T2WI plus CEI for tumor detection and T categorization. The differences in the apparent diffusion coefficient values between tumors and renal parenchyma, histopathologic grade were analyzed.

RESULTS

T2WI plus CEI or DWI had high detection rates (93.4%) compared to T2WI alone. When discriminating T3a/T3b, for Reader 1, the use of T2WI plus DWI (88.0%) and T2WI plus CEI (92.0%) was significantly more accurate than T2WI alone (73%), with AUCs of 0.86, 0.86 and 0.77, respectively. For Reader 2, the accuracies were high on all image sets, with AUCs of 0.87-0.95, and the mean ADC of the tumors was significantly lower than that of the normal renal parenchyma. In addition, the mean ADC values of high-grade tumors were significantly lower than that of low-grade tumors.

CONCLUSIONS

DWI and CEI could be more helpful than T2WI alone for preoperative T categorization by less-experienced reader and DWI could be used for preoperative T categorization and for predicting the histopathologic grade of renal pelvic carcinoma.

Discrimination of local recurrence after radical prostatectomy: value of diffusion-weighted magnetic resonance imaging

Background

Multiparametric magnetic resonance is the most accurate imaging technique for prostate cancer detection, staging, localization, and aggressiveness evaluation. We assessed accuracy of diffusion-weighted imaging in local recurrence diagnosis after radical prostatectomy.

Materials and methods

A retrospective study was conducted in 118 patients with findings suggestive of local recurrence in dynamic contrast-enhanced-magnetic resonance imaging. Local recurrence was defined clinically as a rising prostate-specific antigen level (biochemical recurrence) without radiographic evidence of distant metastasis over 6 months after surgery. Eighty-four patients (71.2%) had local recurrence (group 1) and 34 (28.8%) showed no recurrence (group 2). The diagnostic accuracy of diffusion-weighted imaging was assessed, and factors associated with local recurrence were evaluated using multivariate logistic regression analysis. Additional accuracy analysis was carried out according to the size of the nodule.

Results

In post-operative findings, group 1 patients had significantly higher serum prostate-specific antigen (P = 0.001), larger enhancing nodules (P = 0.005), and more positive findings in diffusion-weighted imaging (P = 0.001) than group 2 patients. The sensitivity of diffusion-weighted imaging was significantly higher for nodules ≥1 cm than for all nodules (96.6 vs. 80.9%, P = 0.001), whereas the specificities were equivalent (100.0 vs. 97.1, P = 0.529). In multivariate analysis, a positive finding in diffusion-weighted imaging was the independent predictor of local recurrence (P = 0.005), along with pathologic T stage (P = 0.018).

Conclusions

Diffusion-weighted imaging is accurate in distinguishing recurrence from enhancing nodule on dynamic contrast-enhanced-magnetic resonance. Nodules showing decreased diffusion suggest local recurrence, especially if sized ≥1 cm.

Multiparametric Magnetic Resonance Imaging of Recurrent Prostate Cancer

There is growing consensus that multiparametric magnetic resonance imaging (mpMRI) is an effective modality in the detection of locally recurrent prostate cancer after prostatectomy and radiation therapy. The emergence of magnetic resonance (MR)-guided focal therapies, such as cryoablation, high-intensity focused ultrasound, and laser ablation, have made the use of mpMRI even more important, as the normal anatomy is inevitably altered and the detection of recurrence is made more difficult. The aim of this article is to review the utility of mpMRI in detecting recurrent prostate cancer in patients following radical prostatectomy, radiation therapy, and focal therapy and to discuss expected post-treatment mpMRI findings, the varied appearance of recurrent tumors, and their mimics.

Detection of prostate cancer local recurrence following radical prostatectomy: assessment using a continuously acquired radial golden-angle compressed sensing acquisition

PURPOSE

To compare image quality and diagnostic performance for detecting local recurrence (LR) of prostate cancer after radical prostatectomy (RP) between standard dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) and a high spatiotemporal resolution, continuously acquired Golden-angle RAdial Sparse Parallel acquisition employing compressed sensing reconstruction ("GRASP").

METHODS

A search was conducted for prostate MRI examinations performed in patients with PSA ≥0.2 ng/mL after RP in whom follow-up evaluation allowed classification as positive (≥50% PSA reduction after pelvic radiation or positive biopsy) or negative (<50% PSA reduction after pelvic radiation; spontaneous PSA normalization) for LR, yielding 13 patients with standard DCE (11 LR+) and 12 with GRASP (10 LR+). Standard DCE had voxel size 3.0 × 1.9 × 1.9 mm and temporal resolution 5.5 s. GRASP had voxel size 1.0 × 1.1 × 1.1 cm and was retrospectively reconstructed at 2.3 s resolution. Two radiologists evaluated DCE sequences for image quality measures (1-5 scale) and the presence of LR.

RESULTS

GRASP achieved higher scores than standard DCE from both readers (p < 0.001-0.136) for anatomic clarity (R1: 4.4 ± 0.8 vs. 2.8 ± 0.67 R2: 4.8 ± 0.5 vs. 3.2 ± 0.6), sharpness (3.6 ± 0.9 vs. 2.5 ± 0.7; 4.6 ± 0.5 vs. 2.6 ± 0.5), confidence in interpretation (3.8 ± 0.8 vs. 3.1 ± 0.9; 3.8 ± 1.0 vs. 3.1 ± 1.2), and conspicuity of detected lesions (4.7 ± 0.5 vs. 3.8 ± 1.1; 4.5 ± 0.5 vs. 3.8 ± 1.0). For detecting LR, GRASP also achieved higher sensitivity (70% vs. 36%; 80% vs. 45%), specificity (R1 and R2: 100% vs. 50%), and accuracy (75% vs. 38%; 83% vs. 46%) for both readers.

CONCLUSION

Although requiring larger studies, high spatiotemporal resolution GRASP achieved substantially better image quality and diagnostic performance than standard DCE for detecting LR in patients with elevated PSA after prostatectomy.

PRECISION MANAGEMENT OF LOCALIZED PROSTATE CANCER

INTRODUCTION

The vast majority of men who are diagnosed with prostate cancer die of other causes, highlighting the importance of determining which patient has a risk of death from prostate cancer. Precision management of prostate cancer patients includes distinguishing which men have potentially lethal disease and employing strategies for determining which treatment modality appropriately balances the desire to achieve a durable response while preventing unnecessary overtreatment.

AREAS COVERED

In this review, we highlight precision approaches to risk assessment and a context for the precision-guided application of definitive therapy. We focus on three dilemmas relevant to the diagnosis of localized prostate cancer: screening, the decision to treat, and postoperative management.

EXPERT COMMENTARY

In the last five years, numerous precision tools have emerged with potential benefit to the patient. However, to achieve optimal outcome, the decision to employ one or more of these tests must be considered in the context of prevailing conventional factors. Moreover, performance and interpretation of a molecular or imaging precision test remains practitioner-dependent. The next five years will witness increased marriage of molecular and imaging biomarkers for improved multi-modal diagnosis and discrimination of disease that is aggressive versus truly indolent.

Localizing sites of disease in patients with rising serum prostate-specific antigen up to 1ng/ml following prostatectomy: How much information can conventional imaging provide?

PURPOSE

Accurate identification of the source of a detectable serum prostate-specific antigen (PSA) in the postprostatectomy setting is a major challenge among the urologic community. The aim of this study was to assess positivity rates of imaging examinations performed in patients with early PSA rise after prostatectomy and to summarize the management strategies adopted in this clinical scenario.

METHODS

Institutional Review Board-approved retrospective study of 142 postprostatectomy patients with PSA rise up to 1ng/ml who underwent evaluation with combination of multiparametric pelvic magnetic resonance imaging (MRI)±whole-body or bone MRI, bone scintigraphy, computed tomography (CT) chest-abdomen-pelvis, ¹⁸F-fludeoxyglucose-positron emission tomography (PET)/CT or ¹⁸F-sodium fluoride-PET/CT at a single tertiary cancer center. Imaging results were summarized per modality and compared with pathology findings.

RESULTS

Pelvic MRI was positive in 15/142 (11%) patients (14 patients with local recurrence in the surgical bed and 1 patient with pelvic osseous metastases). Of these 15, 10 patients underwent additional imaging examinations; none revealed positive findings. Of the 127 patients with negative pelvic MRI, 54 (43%) underwent additional imaging examinations; only 1/54 had positive findings (false-positive T8 lesion on bone scintigraphy and FDG-PET/CT; biopsy was negative for cancer). Overall, 12/16 patients with positive imaging findings and 75/126 (60%) patients with negative imaging received treatment (radiation, hormones or chemotherapy).

CONCLUSION

The conventional imaging identified sites of disease, almost always in the form of local recurrence, in a minority of patients with early PSA rise postprostatectomy.

Multiparametric magnetic resonance imaging: Current role in prostate cancer management

Digital rectal examination, serum prostate-specific antigen screening and transrectal ultrasound-guided biopsy are conventionally used as screening, diagnostic and surveillance tools for prostate cancer. However, they have limited sensitivity and specificity. In recent years, the role of multiparametric magnetic resonance imaging has steadily grown, and is now part of the standard clinical management in many institutions. In multiparametric magnetic resonance imaging, the morphological assessment of T2-weighted imaging is correlated with diffusion-weighted imaging, dynamic contrast-enhanced imaging perfusion and/or magnetic resonance spectroscopic imaging. Multiparametric magnetic resonance imaging is currently regarded as the most sensitive and specific imaging technique for the evaluation of prostate cancer, including detection, staging, localization and aggressiveness evaluation. This article presents an overview of multiparametric magnetic resonance imaging, and discusses the current role of multiparametric magnetic resonance imaging in the different fields of prostate cancer management.

Prostate cancer post-treatment follow-up and recurrence evaluation

Recurrent prostate cancer following primary treatment is common, and the population of men with biochemical recurrence is complex. Conventional management of recurrent prostate cancer involves nontargeted and/or systemic therapies, without defining an individual patient's specific disease. However, recent advances in imaging enable a shift in the management of recurrent prostate cancer to targeted, patient-specific approaches. Specifically, MRI can detect and define local prostate cancer recurrence early in the course of disease, and prostate-specific PET imaging greatly improves nodal staging and can detect previously unknown distant metastases. The significant advances in the imaging of both local and distant tumor recurrences allows for specific selection of treatment options tailored to patients and their disease with less associated morbidity.

Current role of multiparametric magnetic resonance imaging for prostate cancer

Multiparametric magnetic resonance imaging (mp-MRI) has shown promising results in diagnosis, localization, risk stratification and staging of clinically significant prostate cancer, and targeting or guiding prostate biopsy. mp-MRI consists of T2-weighted imaging (T2WI) combined with several functional sequences including diffusion-weighted imaging (DWI), perfusion or dynamic contrast-enhanced imaging (DCEI) and spectroscopic imaging. Recently, mp-MRI has been used to assess prostate cancer aggressiveness and to identify anteriorly located tumors before and during active surveillance. Moreover, recent studies have reported that mp-MRI is a reliable imaging modality for detecting local recurrence after radical prostatectomy or external beam radiation therapy. Because assessment on mp-MRI can be subjective, use of the newly developed standardized reporting Prostate Imaging and Reporting Archiving Data System (PI-RADS) scoring system and education of specialist radiologists are essential for accurate interpretation. This review focuses on the current place of mp-MRI in prostate cancer and its evolving role in the management of prostate cancer.

Role of MRI in the diagnosis and management of prostate cancer

Multiparametric MRI of the prostate consists of T1- and T2-weighted sequences, which provide anatomical information, and one or more 'functional' sequences, that is, diffusion-weighted imaging, dynamic contrast-enhanced sequences and magnetic resonance spectroscopy. Prostate MRI is the most accurate imaging method for local staging of prostate cancer and can also be used for the noninvasive evaluation of tumor aggressiveness. By magnetic resonance-guided prostate biopsy it is possible to target the most cancer-suspicious areas of the gland, especially in patients with a negative transrectal biopsy. In patients with biochemical recurrence after radical treatment, MRI is a valuable tool for the detection of local tumor recurrence and whole-body MRI can be used for the diagnosis of distant metastases.

Multiparametric magnetic resonance imaging-transrectal ultrasound fusion-assisted biopsy for the diagnosis of local recurrence after radical prostatectomy

OBJECTIVE

Approximately 15% of patients who undergo radical prostatectomy (RP) for prostate cancer develop local recurrence, which is heralded by a rise in serum prostate-specific antigen (PSA) levels. Early detection and treatment of recurrence improves the outcome of salvage treatment. We investigated the ability of multiparametric magnetic resonance imaging (mpMRI)-transrectal ultrasound (TRUS) fusion-guided biopsy (FGB) combined with "cognitive biopsy" to confirm local recurrence of prostate cancer after RP.

MATERIALS AND METHODS

In this retrospective study conducted between January 2010 and December 2014, patients with rising PSA levels after RP who had no known evidence of distant metastases underwent mpMRI including T2-weighted (T2W) imaging, diffusion-weighted imaging, dynamic contrast-enhanced (DCE) MRI at 3 Tesla, and subsequent MRI-ultrasound fusion biopsy with cognitive assistance. The detection rate of locally recurrent disease was determined.

RESULTS

A total of 10 patients (mean age = 67y, mean PSA level = 3.44ng/ml) met the inclusion criteria. Of the 10 patients, all had positive findings suspicious for local recurrence on mpMRI per entrance criterion. The most important features on mpMRI were early enhancement on DCE MR images and hypointensity on T2W images. The average lesion diameter on mpMRI was 1.12cm (range: 0.40-2.20cm). All suspicious lesions (16/16, 100%) were positive on T2W MR images, 14 (89%) showed positive features on apparent diffusion coefficient maps of diffusion-weighted images, and 16 (100%) were positive on DCE MR images. MRI-TRUS FGBs were positive in 10/16 lesions (62.5%) and 8/10 (80%) patients.

CONCLUSION

MRI-TRUS FGB with cognitive assistance is able to detect and diagnose locally recurrent lesions after RP, even at low PSA levels. This may facilitate early detection of recurrent disease and improve salvage treatment outcomes.

Interactive Feature Space Explorer© for multi-modal magnetic resonance imaging

Wider information content of multi-modal biomedical imaging is advantageous for detection, diagnosis and prognosis of various pathologies. However, the necessity to evaluate a large number images might hinder these advantages and reduce the efficiency. Herein, a new computer aided approach based on the utilization of feature space (FS) with reduced reliance on multiple image evaluations is proposed for research and routine clinical use. The method introduces the physician experience into the discovery process of FS biomarkers for addressing biological complexity, e.g., disease heterogeneity. This, in turn, elucidates relevant biophysical information which would not be available when automated algorithms are utilized. Accordingly, the prototype platform was designed and built for interactively investigating the features and their corresponding anatomic loci in order to identify pathologic FS regions. While the platform might be potentially beneficial in decision support generally and specifically for evaluating outlier cases, it is also potentially suitable for accurate ground truth determination in FS for algorithm development. Initial assessments conducted on two different pathologies from two different institutions provided valuable biophysical perspective. Investigations of the prostate magnetic resonance imaging data resulted in locating a potential aggressiveness biomarker in prostate cancer. Preliminary findings on renal cell carcinoma imaging data demonstrated potential for characterization of disease subtypes in the FS.

Multiparametric magnetic resonance imaging for prostate cancer: A review and update for urologists

Recently, imaging of prostate cancer has greatly advanced since the introduction of multiparametric magnetic resonance imaging (mpMRI). mpMRI consists of T2-weighted sequences combined with several functional sequences including diffusion-weighted imaging, dynamic contrast-enhanced imaging, and/or magnetic resonance spectroscopy imaging. Interest has been growing in mpMRI because no single MRI sequence adequately detects and characterizes prostate cancer. During the last decade, the role of mpMRI has been expanded in prostate cancer detection, staging, and targeting or guiding prostate biopsy. Recently, mpMRI has been used to assess prostate cancer aggressiveness and to identify anteriorly located tumors before and during active surveillance. Moreover, recent studies have reported that mpMRI is a reliable imaging modality for detecting local recurrence after radical prostatectomy or external beam radiation therapy. In this regard, some urologic clinical practice guidelines recommended the use of mpMRI in the diagnosis and management of prostate cancer. Because mpMRI is the evolving reference standard imaging modality for prostate cancer, urologists should acquire cutting-edge knowledge about mpMRI. In this article, we review the literature on the use of mpMRI in urologic practice and provide a brief description of techniques. More specifically, we state the role of mpMRI in prostate biopsy, active surveillance, high-risk prostate cancer, and detection of recurrence after radical prostatectomy.

Defining the learning curve for multiparametric magnetic resonance imaging (MRI) of the prostate using MRI-transrectal ultrasonography (TRUS) fusion-guided transperineal prostate biopsies as a validation tool

OBJECTIVES

To determine the accuracy of multiparametric magnetic resonance imaging (mpMRI) during the learning curve of radiologists using MRI targeted, transrectal ultrasonography (TRUS) guided transperineal fusion biopsy (MTTP) for validation.

PATIENTS AND METHODS

Prospective data on 340 men who underwent mpMRI (T2-weighted and diffusion-weighted MRI) followed by MTTP prostate biopsy, was collected according to Ginsburg Study Group and Standards for Reporting of Diagnostic Accuracy standards. MRI data were reported by two experienced radiologists and scored on a Likert scale. Biopsies were performed by consultant urologists not 'blinded' to the MRI result and men had both targeted and systematic sector biopsies, which were reviewed by a dedicated uropathologist. The cohorts were divided into groups representing five consecutive time intervals in the study. Sensitivity and specificity of positive MRI reports, prostate cancer detection by positive MRI, distribution of significant Gleason score and negative MRI with false negative for prostate cancer were calculated. Data were sequentially analysed and the learning curve was determined by comparing the first and last group.

RESULTS

We detected a positive mpMRI in 64 patients from Group A (91%) and 52 patients from Group E (74%). The prostate cancer detection rate on mpMRI increased from 42% (27/64) in Group A to 81% (42/52) in Group E (P < 0.001). The prostate cancer detection rate by targeted biopsy increased from 27% (17/64) in Group A to 63% (33/52) in Group E (P < 0.001). The negative predictive value of MRI for significant cancer (>Gleason 3+3) was 88.9% in Group E compared with 66.6% in Group A.

CONCLUSION

We demonstrate an improvement in detection of prostate cancer for MRI reporting over time, suggesting a learning curve for the technique. With an improved negative predictive value for significant cancer, decision for biopsy should be based on patient/surgeon factors and risk attributes alongside the MRI findings.

Improving prediction of prostate cancer recurrence using chemical imaging

Precise Outcome prediction is crucial to providing optimal cancer care across the spectrum of solid cancers. Clinically-useful tools to predict risk of adverse events (metastases, recurrence), however, remain deficient. Here, we report an approach to predict the risk of prostate cancer recurrence, at the time of initial diagnosis, using a combination of emerging chemical imaging, a diagnostic protocol that focuses simultaneously on the tumor and its microenvironment, and data analysis of frequent patterns in molecular expression. Fourier transform infrared (FT-IR) spectroscopic imaging was employed to record the structure and molecular content from tumors prostatectomy. We analyzed data from a patient cohort that is mid-grade dominant – which is the largest cohort of patients in the modern era and in whom prognostic methods are largely ineffective. Our approach outperforms the two widely used tools, Kattan nomogram and CAPRA-S score in a head-to-head comparison for predicting risk of recurrence. Importantly, the approach provides a histologic basis to the prediction that identifies chemical and morphologic features in the tumor microenvironment that is independent of conventional clinical information, opening the door to similar advances in other solid tumors.

Magnetic resonance imaging/positron emission tomography provides a roadmap for surgical planning and serves as a predictive biomarker in patients with recurrent gynecological cancers undergoing pelvic exenteration

OBJECTIVE

Magnetic resonance imaging (MRI) is the modality of choice for staging gynecological cancers owing to its superb soft tissue resolution, whereas F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) allows the assessment of glycolytic activity within the tumor microenvironment. In this study, we evaluated the incremental value of fused MRI/PET over MRI or fluorodeoxyglucose PET/CT alone for assessing local disease extent in patients with recurrent gynecological cancers undergoing pelvic exenteration and determined the associations between imaging findings and clinical outcomes in this patient population.

MATERIALS AND METHODS

The institutional review board approved this retrospective, Health Insurance Portability and Accountability Act (HIPAA)-compliant study of 31 patients who underwent pelvic MRI and PET/CT 3 months or less before pelvic exenteration for recurrent cancers of the uterine cervix, corpus, or vulva/vagina. Using a 1 to 5 scale (1, definitely not present; 5, definitely present), 2 readers independently evaluated MRI, PET/CT, and fused MRI/PET images for the presence of bladder, rectum, and pelvic sidewall invasion. Surgical pathology constituted the reference standard. Measurements of diagnostic accuracy, interreader agreement, and associations between imaging findings and progression-free survival and overall survival were calculated.

RESULTS

Compared with MRI or PET/CT, fused MRI/PET correctly improved readers' diagnostic confidence in detecting bladder, rectum, or pelvic sidewall invasion in up to 52% of patients. Interreader agreement was consistently in the highest ("almost perfect") range only for MRI/PET (κ = 0.84-1.0). The highest sensitivities (0.82-1.0), specificities (0.91-1.0), and predictive values (0.80-1.0) were consistently achieved with fused MRI/PET (although the differences were not statistically significant [P > 0.05]). Pelvic sidewall invasion on MRI/PET was the only finding significantly associated with both progression-free and overall survival for both readers (P = 0.0067-0.0440).

CONCLUSIONS

In patients with recurrent gynecological cancers undergoing pelvic exenteration, fused MRI/PET served as a predictive biomarker and yielded greater diagnostic confidence and interreader agreement than either MRI or PET/CT.

The expanding role of MRI in prostate cancer

OBJECTIVE

The purpose of this article is to review the many evolving facets of MRI in the evaluation of prostate cancer. We will discuss the roles of multiparametric MRI, including diffusion-weighted MRI, dynamic contrast-enhanced MRI, and MR spectroscopy, as adjuncts to morphologic T2-weighted imaging in detection, staging, treatment planning, and surveillance of prostate cancer.

CONCLUSION

Radiologists need to understand the advantages, limitations, and potential pitfalls of the different sequences to provide optimal assessment of prostate cancer.

Detection of recurrent prostate cancer after radical prostatectomy: comparison of 11C-choline PET/CT with pelvic multiparametric MR imaging with endorectal coil

The aim of this study was to compare (11)C-choline PET/CT with pelvic multiparametric MR imaging for detection of recurrent prostate carcinoma in patients with suspected recurrence after radical prostatectomy and to identify an optimal imaging method to restage these patients.

METHODS

This was a retrospective, single-institution study of 115 prostatectomy patients with suspected tumor recurrence who underwent both (11)C-choline PET/CT and multiparametric MR imaging with endorectal coil. The reference standard included histopathology, treatment change, and imaging follow-up for determination of locally recurrent tumor, lymph node (LN) metastases, and skeletal metastases. Two nuclear medicine and 2 genitourinary radiologists independently and in a masked manner reviewed PET/CT and multiparametric MR imaging, respectively. The reviewers assessed for local recurrence in the prostatectomy bed as well as LN and bone metastases, rating their diagnostic confidence with a 5-point scoring system for each location. Receiver-operating-characteristic analysis was used to compare the 2 modalities.

RESULTS

The standard of reference (either positive or negative) for the diagnosis of local recurrence and pelvic LN and bone metastases was met in 87, 70, and 95 patients, respectively. Documented local recurrence and pelvic LN and bone metastases was present in 61 of 87 (70.1%), 50 of 70 (71.4%), and 16 of 95 (16.8%) patients, respectively. Patient-based area under the receiver-operating-characteristic curves of multiparametric MR imaging versus PET/CT for the diagnosis of local recurrence and pelvic LN and bone metastases were 0.909 versus 0.761 (P = 0.0079), 0.812 versus 0.952 (P = 0.0064), and 0.927 versus 0.898 (P = 0.69), respectively. Among 61 patients with local recurrence, 32 patients (52.4%) were correctly diagnosed as having local recurrence by both multiparametric MR imaging and PET/CT, 22 (36.1%) were correctly diagnosed by multiparametric MR imaging only, 6 (9.8%) could not be diagnosed by either modality, and 1 (1.6%) was correctly diagnosed by PET/CT only. The patient-based sensitivity, specificity, and accuracy of multiparametric MR imaging for diagnosing local recurrence were 88.5% (54/61), 84.6% (22/26), and 87.4% (76/87) whereas those of PET/CT for detecting body LN or bone metastases were 92.3% (72/78), 100% (18/18), and 93.8% (90/96), respectively.

CONCLUSION

Multiparametric MR imaging with endorectal coil is superior for the detection of local recurrence, PET/CT is superior for pelvic LN metastasis, and both were equally excellent for pelvic bone metastasis. (11)C-choline PET/CT and pelvic multiparametric MR imaging are complementary for restaging prostatectomy patients with suspected recurrent disease.

Role of MRI in prostate cancer detection

The standard approach for the detection of prostate cancer--prostate-specific antigen (PSA) screening followed by transrectal ultrasonography (TRUS)-guided biopsy--has low sensitivity and provides limited information about the true extent and aggressiveness of the cancer. Improved methods are needed to assess the extent and aggressiveness of the cancer and to identify patients who will benefit from therapy. In recent years, there has been tremendous development of acquisition and processing tools for physiological and metabolic MRI techniques which play a potential role in the detection, localization and characterization of prostate cancer, such as dynamic contrast-enhanced MRI (DCE-MRI), diffusion-weighted MRI (DW-MRI) and/or proton MR spectroscopic imaging ((1)H MRSI). The standard protocol for prostate MRI without the use of a contrast agent involves multi-planar T1 -weighted MRI, T2 -weighted MRI and DW-MRI. This review discusses the potential role of MRI in the detection of prostate cancer, specifically describing the status of MRI as a tool for guiding targeted prostate biopsies and for detecting cancer in the untreated and treated gland. In addition, future areas of MRI research are briefly discussed. Groups conducting clinical trials should consider the recommendations put forward by the European Consensus Meeting, which state that the minimum requirements for prostate MRI are T1 -weighted MRI, T2 -weighted MRI, DCE-MRI (which involves the use of a contrast agent) and DW-MRI with a pelvic phased-array coil and propose the use of transperineal template mapping biopsies as the optimal reference standard.

Prostate cancer localization using multiparametric MR imaging: comparison of Prostate Imaging Reporting and Data System (PI-RADS) and Likert scales

PURPOSE

To compare the recently proposed Prostate Imaging Reporting and Data System (PI-RADS) scale that incorporates fixed criteria and a standard Likert scale based on overall impression in prostate cancer localization using multiparametric magnetic resonance (MR) imaging.

MATERIALS AND METHODS

This retrospective study was HIPAA compliant and institutional review board approved. Seventy patients who underwent 3-T pelvic MR imaging, including T2-weighted imaging, diffusion-weighted imaging, and dynamic contrast material-enhanced imaging, with a pelvic phased-array coil before radical prostatectomy were included. Three radiologists, each with 6 years of experience, independently scored 18 regions (12 peripheral zone [PZ], six transition zone [TZ]) using PI-RADS (range, scores 3-15) and Likert (range, scores 1-5) scales. Logistic regression for correlated data was used to compare scales for detection of tumors larger than 3 mm in maximal diameter at prostatectomy.

RESULTS

Maximal accuracy was achieved with score thresholds of 8 and higher and of 3 and higher for PI-RADS and Likert scales, respectively. At these thresholds, in the PZ, similar accuracy was achieved with the PI-RADS scale and the Likert scale for radiologist 1 (89.0% vs 88.2%, P = .223) and radiologist 3 (88.5% vs 88.2%, P = .739) and greater accuracy was achieved with the PI-RADS scale than the Likert scale for radiologist 2 (89.6% vs 87.1%, P = .008). In the TZ, accuracy was lower with the PI-RADS scale than with the Likert scale for radiologist 1 (70.0% vs 87.1%, P < .001), radiologist 2 (87.6% vs 92.6%, P = .002), and radiologist 3 (82.9% vs 91.2%, P < .001). For tumors with Gleason score of at least 7, sensitivity was higher with the PI-RADS scale than with the Likert scale for radiologist 1 (88.6% vs 82.6%, P = .032), and sensitivity was similar for radiologist 2 (78.0% vs 76.5, P = .467) and radiologist 3 (77.3% vs 81.1%, P = .125).

CONCLUSION

Radiologists performed well with both PI-RADS and Likert scales for tumor localization, although, in the TZ, performance was better with the Likert scale than the PI-RADS scale.

SUPPLEMENTAL MATERIAL

http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.13122233/-/DC1.