Comparison of magnetic resonance imaging and ultrasound (MRI-US) fusion-guided prostate biopsies obtained from axial and sagittal approaches

Intra-practice Urologist-level Variation in Targeted Fusion Biopsy Outcomes

OBJECTIVE

To examine the extent to which the urologist performing biopsy contributes to variation in prostate cancer detection during fusion-guided prostate biopsy.

METHODS

All men in the Michigan Urological Surgery Improvement Collaborative (MUSIC) clinical registry who underwent fusion biopsy at Michigan Medicine from August 2017 to March 2019 were included. The primary outcomes were clinically significant cancer detection rate (defined as Gleason Grade ≥2) in targeted cores and clinically significant cancer detection on targeted cores stratified by PI-RADS score. Bivariate and multivariable logistic regression analyses were performed.

RESULTS

A total of 1133 fusion biopsies performed by 5 providers were included. When adjusting for patient age, PSA, race, family history, prostate volume, clinical stage, and PI-RADS score, there was no significant difference in targeted clinically significant cancer detection rates across providers (range = 38.5%-46.9%, adjusted P-value = .575). Clinically significant cancer detection rates ranged from 11.1% to 16.7% in PI-RADS 3 (unadjusted P = .838), from 24.6% to 43.4% in PI-RADS 4 (adjusted P = .003), and from 69.4% to 78.8% in PI-RADS 5 (adjusted P = .766) lesions.

CONCLUSION

There was a statistically significant difference in clinically significant prostate cancer detection in PI-RADS 4 lesions across providers. These findings suggest that even among experienced providers, variation at the urologist level may contribute to differences in clinically significant cancer detection rates within PI-RADS 4 lesions. However, the relative impact of biopsy technique, radiologist interpretation, and MR acquisition protocol requires further study.

Diagnosis and Pathologic Reporting of Prostate Cancer in the Era of MRI-Targeted Prostate Biopsy

Historically, the detection of prostate cancer relied upon a systematic yet random sampling of the prostate by transrectal ultrasound guided biopsy. This approach was a nontargeted technique that led to the under detection of cancers at biopsy and the upgrading of cancers at radical prostatectomy. Multiparametric MRI-targeted prostate biopsy allows for an image-directed approach to the identification of prostate cancer. MRI-targeted biopsy of the prostate is superior for the detection of clinically significant prostate cancer. As this technique has become more prevalent among urologists, pathologists need to recognize how this development impacts cancer diagnosis and reporting.

Multifocality of Prostate Cancer and Candidacy for Focal Therapy Based on Magnetic Resonance Imaging

OBJECTIVES

To determine the prevalence of multiparametric magnetic resonance imaging (mpMRI)-detected and targeted biopsy-confirmed multifocal and unifocal prostate cancer (PCa) among patients with Prostate Imaging Reporting and Data System (PI-RADS) ≥3 lesions. Focal therapy (FT) options for PCa are tied to accurate spatial identification on mpMRI.

METHODS

Men without prior diagnosis of PCa receiving mpMRI, targeted and systematic prostate biopsy in the Prospective Loyola Urology mpMRI (PLUM) Prostate Biopsy Cohort from 2015-2021 were included. Patients with PI-RADS ≥3 lesions were classified by mpMRI lesion location, targeted biopsy, and systematic biopsy. Patients with single biopsy-confirmed grade group (GG) 2 lesions and concordant systematic biopsy were defined as FT candidates. Multivariable logistic regression evaluated predictors of mpMRI-undetected contralateral PCa.

RESULTS

Of 897 patients, 450 (50.2%) had a single, 141 (15.7%) had multiple unilateral, and 306 (34.1%) had bilateral mpMRI lesions. 28.7% had a single targeted biopsy-confirmed lesion while 10.4% were multifocal. Among single targeted biopsy-confirmed patients, 92/257 (35.8%) had contralateral PCa missed by mpMRI with DRE, PSA, and biopsy history identified as independent predictors. Systematic biopsy findings dropped the rate of single confirmed lesions from 28.7% to 18.4% and multifocal PCa increased from 10.4% to 20.6%. After GG restrictions, 61/897 (6.8%) remained potential FT candidates.

CONCLUSIONS

Among men with clinical suspicion of prostate cancer receiving mpMRI, 28.7% had a single targeted biopsy-confirmed lesion and 10.4% had multifocality on mpMRI, but many mpMRI-undetected contralateral PCa were identified. Only 6.0% of biopsy-naïve men remained with a single GG2 mpMRI lesion potentially amenable to FT.

Transrectal ultrasound-guided prostate biopsy versus combined magnetic resonance imaging-ultrasound fusion and systematic biopsy for prostate cancer detection in routine clinical practice

PURPOSE

The goal of this study was to retrospectively compare systematic ultrasound-guided prostate biopsy (US-PB) and multiparametric magnetic resonance imaging-ultrasound fusion prostate biopsy (MRI-PB) in men undergoing primary or repeated biopsies.

METHODS

A population of 2,200 patients with a prostate-specific antigen (PSA) level >4.0 ng/ dL and/or an abnormal rectal examination was divided into two groups. All patients underwent US-PB (n=1,021) or MRI-PB (n=1,179) between April 2015 and April 2019. Population demographics, including age, PSA level, digital rectal examination results, prostate volume, number of previous negative biopsies, Prostate Imaging Reporting and Data System (PI-RADS) version 2 (V2) score, and biopsy results, were acquired and compared with respect to these variables. Univariate regression analysis of the risk factors for a higher Gleason score (GS) was performed.

RESULTS

The cancer detection rate (CDR) was 23.8% (243 of 1,021) in the US-PB group and 31.3% (399 of 1,179) in the MRI-PB group. Of those, 225 patients (22.0%) in the US-PB group and 374 patients (31.7%) in the MRI-PB group had clinically significant prostate cancer (csPCa). The patients with csPCa in the MRI-PB group included 10 (40%), 50 (62.5%), 184 (94.8%), and 32 (94.1%) patients with PI-RADS V2 scores of 2, 3, 4, and 5, respectively. Of the patients with csPCa, 155 (91.7%) in the US-PB group were diagnosed on the basis of the primary biopsy, compared to 308 (94.4%) in the MRI-PB group. We found the PI-RADS V2 score to be the best predictor of a higher GS.

CONCLUSION

MRI-PB showed a high CDR for csPCa. MRI-PB could be a reasonable approach in patients with high PI-RADS V2 scores at primary biopsy.

A Magnetic Resonance Imaging-Based Prediction Model for Prostate Biopsy Risk Stratification

Importance

Multiparametric magnetic resonance imaging (MRI) in conjunction with MRI-transrectal ultrasound (TRUS) fusion-guided biopsies have improved the detection of prostate cancer. It is unclear whether MRI itself adds additional value to multivariable prediction models based on clinical parameters.

Objective

To determine whether an MRI-based prediction model can reduce unnecessary biopsies in patients with suspected prostate cancer.

Design, Setting, and Participants

Patients underwent MRI, MRI-TRUS fusion-guided biopsy, and 12-core systematic biopsy in 1 session. The development cohort used to derive the prediction model consisted of 400 patients from 1 institution enrolled between May 14, 2015, and August 31, 2016, and the validation cohort included 251 patients from 2 independent institutions who underwent biopsies between April 1, 2013, and June 30, 2016, at 1 institution and between July 1, 2015, and October 31, 2016, at the other institution. The MRI model included MRI-derived parameters in addition to clinical variables. Area under the curve of receiver operating characteristic curves and decision curve analysis were performed.

Main Outcomes and Measures

Risk of clinically significant prostate cancer on biopsy, defined as a Gleason score of 3 + 4 or higher in at least 1 biopsy core.

Results

Overall, 193 (48.3%) of the 400 patients in the development cohort (mean [SD] age at biopsy, 64.3 [7.1] years) and 96 (38.2%) of the 251 patients in the validation cohort (mean [SD] age at biopsy, 64.9 [7.2] years) had clinically significant prostate cancer, defined as a Gleason score greater than or equal to 3 + 4. By applying the model to the external validation cohort, the area under the curve increased from 64% to 84% compared with the baseline model (P < .001). At a risk threshold of 20%, the MRI model had a lower false-positive rate than the baseline model (46% [95% CI, 32%-66%] vs 92% [95% CI, 70%-100%]), with only a small reduction in the true-positive rate (89% [95% CI, 85%-96%] vs 99% [95% CI, 89%-100%]). Eighteen of 100 fewer biopsies could have been performed, with no increase in the number of patients with missed clinically significant prostate cancers.

Conclusions and Relevance

The inclusion of MRI-derived parameters in a risk model could reduce the number of unnecessary biopsies while maintaining a high rate of diagnosis of clinically significant prostate cancers.

Intra- and interreader reproducibility of PI-RADSv2: A multireader study

BACKGROUND

The Prostate Imaging Reporting and Data System version 2 (PI-RADSv2) has been in use since 2015; while interreader reproducibility has been studied, there has been a paucity of studies investigating the intrareader reproducibility of PI-RADSv2.

PURPOSE

To evaluate both intra- and interreader reproducibility of PI-RADSv2 in the assessment of intraprostatic lesions using multiparametric magnetic resonance imaging (mpMRI).

STUDY TYPE

Retrospective.

POPULATION/SUBJECTS

In all, 102 consecutive biopsy-naïve patients who underwent prostate MRI and subsequent MR/transrectal ultrasonography (MR/TRUS)-guided biopsy.

FIELD STRENGTH/SEQUENCES

Prostate mpMRI at 3T using endorectal with phased array surface coils (TW MRI, DW MRI with ADC maps and b2000 DW MRI, DCE MRI).

ASSESSMENT

Previously detected and biopsied lesions were scored by four readers from four different institutions using PI-RADSv2. Readers scored lesions during two readout rounds with a 4-week washout period.

STATISTICAL TESTS

Kappa (κ) statistics and specific agreement (Po ) were calculated to quantify intra- and interreader reproducibility of PI-RADSv2 scoring. Lesion measurement agreement was calculated using the intraclass correlation coefficient (ICC).

RESULTS

Overall intrareader reproducibility was moderate to substantial (κ = 0.43-0.67, Po  = 0.60-0.77), while overall interreader reproducibility was poor to moderate (κ = 0.24, Po  = 46). Readers with more experience showed greater interreader reproducibility than readers with intermediate experience in the whole prostate (P = 0.026) and peripheral zone (P = 0.002). Sequence-specific interreader agreement for all readers was similar to the overall PI-RADSv2 score, with κ = 0.24, 0.24, and 0.23 and Po  = 0.47, 0.44, and 0.54 in T2 -weighted, diffusion-weighted imaging (DWI), and dynamic contrast-enhanced (DCE), respectively. Overall intrareader and interreader ICC for lesion measurement was 0.82 and 0.71, respectively.

DATA CONCLUSION

PI-RADSv2 provides moderate intrareader reproducibility, poor interreader reproducibility, and moderate interreader lesion measurement reproducibility. These findings suggest a need for more standardized reader training in prostate MRI.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 2.

Difference in MRI-guided biopsy cancer detection rates between individual clinicians

OBJECTIVE

A number of studies have described the overall institutional learning curve for magnetic resonance imaging-guided biopsy but none have evaluated differences and interactions between clinicians. Therefore, we aim to measure and compare the cancer detection rates between individual radiologists and urologists at a single academic institution.

METHODS

A consecutive sample of patients undergoing magnetic resonance imaging-guided biopsy at a single institution were included for analysis. The detection of any and clinically significant (Gleason score ≥3+4) prostate cancer was compared between radiologists and urologists after adjusting for relevant demographic and clinical characteristics. Analysis was conducted on a perlesion basis and only the results of the targeted cores were considered in the primary analysis.

RESULTS

Two hundred eighty-one patients with 418 lesions were included in the study. Prostate cancer of any grade was detected in 43.7% (183/418) of targeted lesions. There was no difference in the distribution of Prostate Imaging Reporting and Data System (PIRADS) scores attributed by each radiologist (p = 0.43). The individual radiologist cancer detection rate for both overall and clinically significant cancer was similar across each PIRADS score except for the detection of any cancer in PIRADS 3 lesions (p = 0.03). There was no difference in the detection rates of any grade or clinically significant cancer between urologists.

CONCLUSION

This single institutional analysis found that the performance of radiologists and urologists was largely comparable. Theonly variation observed was among radiologists for PIRADS 3 lesions.

Imaging as a Personalized Biomarker for Prostate Cancer Risk Stratification

Biomarkers provide objective data to guide clinicians in disease management. Prostate-specific antigen serves as a biomarker for screening of prostate cancer but has come under scrutiny for detection of clinically indolent disease. Multiple imaging techniques demonstrate promising results for diagnosing, staging, and determining definitive management of prostate cancer. One such modality, multiparametric magnetic resonance imaging (mpMRI), detects more clinically significant disease while missing lower volume and clinically insignificant disease. It also provides valuable information regarding tumor characteristics such as location and extraprostatic extension to guide surgical planning. Information from mpMRI may also help patients avoid unnecessary biopsies in the future. It can also be incorporated into targeted biopsies as well as following patients on active surveillance. Other novel techniques have also been developed to detect metastatic disease with advantages over traditional computer tomography and magnetic resonance imaging, which primarily rely on defined size criteria. These new techniques take advantage of underlying biological changes in prostate cancer tissue to identify metastatic disease. The purpose of this review is to present literature on imaging as a personalized biomarker for prostate cancer risk stratification.

How Would MRI-targeted Prostate Biopsy Alter Radiation Therapy Approaches in Treating Prostate Cancer?

OBJECTIVE

To determine if magnetic resonance imaging (MRI)/ultrasound fusion-targeted prostate biopsy (TB) would lead to increased recommendations of aggressive radiotherapy treatments for higher risk prostate cancer compared to systematic biopsy (SB) results.

METHODS

Clinicopathologic data of 533 men who underwent both TB and SB from 2014 to 2017 was analyzed. TB was performed in addition to SB in patients with detection of MRI suspicious lesions. Three patient cohorts were established: (1) biopsy naïve (80/533, 15.0%), (2) active surveillance (185/533, 34.7%), and (3) prior negative biopsy (268/533, 50.3%). Cancer risk categorical criteria were established with recommended radiotherapy treatment for each. Variation of risk classification due to biopsy method for all patients and within each cohort was analyzed using either a chi-squared statistic or Fisher's exact test. McNemar's pairwise analyses were performed for all risk categories between TB and SB to assess the effects of TB on high-risk cancer identification and subsequent radiotherapy recommendations.

RESULTS

Number of patients within cancer risk categories (1. "No Cancer or Low-Risk"; 2. "More Favorable Intermediate-Risk"; 3. "Less Favorable Intermediate-Risk"; 4. "High-Risk") varied significantly based on TB and SB pathology among all patients combined (P <.0001), in cohort 2 (P = .0005), and in cohort 3 (P <0.0001). Further, among all patients, TB increased cancer risk classification and correspondingly would result in more aggressive radiotherapy recommendations: "No Cancer or Low-Risk" to "Less Favorable Intermediate-Risk" (30/343, P <0.0001) and "No Cancer or Low-Risk" to "High-Risk" (31/353, P <.0001).

CONCLUSION

Among men with prostate cancer, TB commonly led to reclassification to a higher risk group, which is accompanied by more aggressive radiotherapy treatment recommendations when compared with SB findings alone.

Targets missed: predictors of MRI-targeted biopsy failing to accurately localize prostate cancer found on systematic biopsy

BACKGROUND

Magnetic resonance imaging (MRI)/ultrasound (US) fusion-guided biopsy has improved the ability to localize and detect prostate cancer (PCa) with efficiency surpassing systematic biopsy. Nevertheless, some patients have PCa missed using the MRI-targeted biopsy sampling alone. We aim to identify clinical and imaging parameters associated with cases where targeted biopsy did not detect PCa compared to systematic biopsy.

METHODS

We conducted a retrospective review of patients who underwent MRI/US fusion-guided biopsy in addition to concurrent systematic, extended-sextant biopsy between 2014 and 2017. For patients with PCa detected on systematic biopsy not properly localized by MRI/US fusion-guided biopsy, the sextant distance from MRI-targeted lesion to the cancer-positive sextant was calculated and parameters potentially predicting this targeting miss were evaluated.

RESULTS

In all, 35/127 (27.6%) patients with single-session MRI/US fusion-guided biopsy plus standard biopsy finding PCa had lesions incorrectly localized. Of these, 15/35 (42.9%) were identified as possible fusion-software misregistrations. The remainder, 12/35 (34.3%), represented targeted biopsies one sextant away from the cancer focus and 8/35 (22.9%) targeted biopsies two sextants away from the cancer focus. Only 7/35 (20.0%) patients were determined to have clinically significant PCa, which represents 7/127 (5.5%) of the overall population. Lower MRI lesion volumes (p = 0.022), lesion density (p < 0.001), and PI-RADS scores (p < 0.001) were significantly associated with targeted biopsy missing PCa detected on systematic biopsy.

CONCLUSION

Clinically significant PCa is rarely missed utilizing MRI/US fusion-guided biopsy. With the majority of missed tumors representing targeting misregistrations or cases of low-grade cancer in sextants immediately adjacent to MRI suspicious lesions. Lower MRI lesion volumes, lesion density, and PI-RADS are predictors of cases with targeted biopsies missing cancer, for which systematic sampling of the sextants containing MRI targets and adjacent sextants would most optimize PCa detection.

Added Value of Multiparametric Magnetic Resonance Imaging to Clinical Nomograms for Predicting Adverse Pathology in Prostate Cancer

PURPOSE

We examined the additional value of preoperative prostate multiparametric magnetic resonance imaging and transrectal ultrasound/multiparametric magnetic resonance imaging fusion guided targeted biopsy when performed in combination with clinical nomograms to predict adverse pathology at radical prostatectomy.

MATERIALS AND METHODS

We identified all patients who underwent 3 Tesla multiparametric magnetic resonance imaging prior to fusion biopsy and radical prostatectomy. The Partin and the MSKCC (Memorial Sloan Kettering Cancer Center) preradical prostatectomy nomograms were applied to estimate the probability of organ confined disease, extraprostatic extension, seminal vesicle invasion and lymph node involvement using transrectal ultrasound guided systematic biopsy and transrectal ultrasound/multiparametric magnetic resonance imaging fusion guided targeted biopsy Gleason scores. With radical prostatectomy pathology as the gold standard we developed multivariable logistic regression models based on these nomograms before and after adding multiparametric magnetic resonance imaging to assess any additional predictive ability.

RESULTS

A total of 532 patients were included in study. When multiparametric magnetic resonance imaging findings were added to the systematic biopsy based MSKCC nomogram, the AUC increased by 0.10 for organ confined disease (p <0.001), 0.10 for extraprostatic extension (p = 0.003), 0.09 for seminal vesicle invasion (p = 0.011) and 0.06 for lymph node involvement (p = 0.120). Using Gleason scores derived from targeted biopsy compared to systematic biopsy provided an additional predictive value of organ confined disease (Δ AUC 0.07, p = 0.003) and extraprostatic extension (Δ AUC 0.07, p = 0.048) at radical prostatectomy with the MSKCC nomogram. Similar results were obtained using the Partin nomogram.

CONCLUSIONS

Magnetic resonance imaging alone or in addition to standard clinical nomograms provides significant additional predictive ability of adverse pathology at the time of radical prostatectomy. This information can be greatly beneficial to urologists for preoperative planning and for counseling patients regarding the risks of future therapy.

Stereotactic Radiosurgery for Prostate Cancer Following Magnetic Resonance Imaging Directed Biopsy: A Multidisciplinary Approach with Case Examples

Classically, prostate cancer has been diagnosed via systematic, transrectal ultrasound-guided biopsy prompted by an abnormal digital rectal exam or elevated serum prostate-specific antigen (PSA) level. The development of multi-parametric magnetic resonance imaging (MRI) has led to improved detection of prostate cancer foci. For patients with clinically localized prostate cancer seeking definitive therapy through radiation therapy, external beam radiation has been a mainstay with a movement toward hypofractionation, notably prostate stereotactic body radiotherapy (SBRT). We aim to describe the practical aspects of establishing a multidisciplinary, MRI-based prostate SBRT program by means of case examples.

The prostate SBRT team at the University of Alabama at Birmingham has been performing prostate SBRT for over four years using a multidisciplinary workflow. We have additionally completed a phase II trial of prostate SBRT with additional targeting of intraprostatic lesions with higher doses of radiation using a simultaneous integrated boost technique.

While there have been no reported randomized trials of prostate SBRT, this treatment has been proven safe and effective for properly selected patients with low and intermediate-risk prostate cancer. We present our multidisciplinary approach to prostate SBRT with two clinical cases targeting high-risk [MAM1] lesions in different anatomic zones of the prostate highlighting pertinent clinical challenges in successfully delivering prostate SBRT and managing potential side effects.

In conclusion, we report a multidisciplinary, MRI-based approach to treating patients with ultra hyperfractionated stereotactic radiosurgery as primary definitive treatment for prostate cancer.

Multifunctional nanoparticles for real-time evaluation of toxicity during fetal development

Increasing production of nanomaterials in industrial quantities has led to public health concerns regarding exposure, particularly among pregnant women and developing fetuses. Information regarding the barrier capacity of the placenta for various nanomaterials is limited due to challenges working with ex vivo human placentas or in vivo animal models. To facilitate real-time in vivo imaging of placental transport, we have developed a novel, multifunctional nanoparticle, based on a core of mesoporous silica nanoparticles (MSN), and functionalized for magnetic resonance imaging (MRI), ultrasound, and fluorescent microscopy. Our MSN particles were tested as a tracking method for harmful and toxic nanomaterials. In gravid mice, intravenous injections of MSN were administered in the maternal circulation in early gestation (day 9) and late gestation (day 14). MRI and ultrasound were used to track the MSN following the injections. Changes in contrast relative to control mice indicated that MSN were observed in the embryos of mice following early gestation injections, while MSN were excluded from the embryo by the placenta following late gestation injections. The timing of transplacental barrier porosity is consistent with the notion that in mice there is a progressive increasing segregation by the placenta in later gestation. In addition, built-in physico-chemical properties of our MSN may present options for the therapeutic treatment of embryonic exposure. For example, if preventive measures such as detoxification of harmful compounds are implemented, the particle size and exposure timing can be tailored to selectively distribute to the maternal side of the trophoblast or delivered to the fetus.

Multi-institutional nomogram predicting benign prostate pathology on magnetic resonance/ultrasound fusion biopsy in men with a prior negative 12-core systematic biopsy

BACKGROUND

Prostate multiparametric magnetic resonance imaging (mpMRI) may be recommended for patients with a prior negative systematic biopsy (SB). However, a proportion of these patients will continue to have no prostate cancer (PCa) identified on magnetic resonance/ultrasound fusion biopsy (FB) despite abnormal mpMRI findings.

METHODS

In this multi-institutional, retrospective study, clinical and mpMRI parameters were assessed for 285 consecutive patients with at least 1 prior negative biopsy who underwent FB for a Prostate Imaging Reporting and Data System (PI-RADS) score of 3 to 5 at the University of Rochester Medical Center from December 2014 to December 2016, or at the University of Alabama at Birmingham from February 2014 to February 2017. Nomograms were generated for predicting benign prostate pathology on both the targeted biopsy and the concurrent SB.

RESULTS

Benign pathology was found in 132 of 285 patients (46.3%). In a multivariate analysis, the predictors of benign prostate pathology on FB were age, prostate-specific antigen, prostate volume, and PI-RADS score. The predicted probabilities were plotted on a receiver operating characteristic curve, and the area under the curve was 0.825. The nomogram demonstrated excellent calibration and a high net benefit in a decision curve analysis. With a theoretical cutoff probability of ≥0.7 used to recommend deferment of FB, 61 of 285 patients (21.4%) would have avoided an unnecessary biopsy, and only 4 of 285 patients (1.4%) with PCa with a Gleason score ≥ 3 + 4 would have been missed.

CONCLUSIONS

False-positive mpMRI examinations may occur in up to 46.3% of patients with a prior negative biopsy. Thus, a multi-institutional nomogram has been developed and validated for predicting benign pathology after FB in patients with a prior negative biopsy, and this may help to reduce the number of unnecessary biopsies in the setting of abnormal mpMRI findings. Cancer 2018;124:278-85. © 2017 American Cancer Society.

Co-registration of MRI and ultrasound: accuracy of targeting based on radiology-pathology correlation

We reviewed the role of multiparametric magnetic resonance imaging (MP-MRI) and methods of MRI guided biopsy including in-bore, cognitive fusion, and software-based fusion. MP-MRI has been developed, optimized, and studied as a means of improving prostate cancer detection beyond the standard evaluation that utilizes digital rectal examinations and serum prostate specific antigen (PSA). MP-MRI has been proven to be an excellent diagnostic imaging modality that improves prostate cancer detection and risk stratification by guiding biopsy samples. The co-registration between MRI and ultrasound has allowed for software-based fusion which enables office-based biopsy procedures while still benefiting from the detailed prostate characterization of MRI. MP-MRI/ultrasound fusion guided biopsy has been studied in detail as this technology has been developed, tested, and validated in the past decade. The imaging to pathology correlation supporting the use of MP-MRI/ultrasound fusion is well documented in the literature. As the indication for the use of prostate MP-MRI becomes more widespread, it is important to continue to evaluate the correlation between imaging and pathologic findings.

MR/US Fusion Technology: What Makes It Tick?

MR/US fusion biopsy has emerged as a significant refinement of traditional prostate cancer diagnostic techniques. Utilizing not only quantitative imaging suspicion information from mpMRI but also the spatial accuracy and three-dimensional localization allows such strategies to specifically sample areas of concern with the gland. As such, diagnostic certainty is markedly improved. In this manuscript, we aim to highlight the multidisciplinary approach (amongst urologists, radiologists, pathologists, imaging technologists, nursing staff, and patients) which is required to launch and maintain a successful prostate imaging program.

Customized Tool for the Validation of Optical Coherence Tomography in Differentiation of Prostate Cancer

OBJECTIVE

To design and demonstrate a customized tool to generate histologic sections of the prostate that directly correlate with needle-based optical coherence tomography pullback measurements.

MATERIALS AND METHODS

A customized tool was created to hold the prostatectomy specimens during optical coherence tomography measurements and formalin fixation. Using the tool, the prostate could be sliced into slices of 4 mm thickness through the optical coherence tomography measurement trajectory. In this way, whole-mount pathology slides were produced in exactly the same location as the optical coherence tomography measurements were performed. Full 3-dimensional optical coherence tomography pullbacks were fused with the histopathology slides using the 3-dimensional imaging software AMIRA, and images were compared.

RESULTS

A radical prostatectomy was performed in a patient (age: 68 years, prostate-specific antigen: 6.0 ng/mL) with Gleason score 3 + 4 = 7 in 2/5 biopsy cores on the left side (15%) and Gleason score 3 + 4 = 7 in 1/5 biopsy cores on the right side (5%). Histopathology after radical prostatectomy showed an anterior located pT2cNx adenocarcinoma (Gleason score 3 + 4 = 7). Histopathological prostate slides were produced using the customized tool for optical coherence tomography measurements, fixation, and slicing of the prostate specimens. These slides correlated exactly with the optical coherence tomography images. Various structures, for example, Gleason 3 + 4 prostate cancer, stroma, healthy glands, and cystic atrophy with septae, could be identified both on optical coherence tomography and on the histopathological prostate slides.

CONCLUSION

We successfully designed and applied a customized tool to process radical prostatectomy specimens to improve the coregistration of whole mount histology sections to fresh tissue optical coherence tomography pullback measurements. This technique will be crucial in validating the results of optical coherence tomography imaging studies with histology and can easily be applied in other solid tissues as well, for example, lung, kidney, breast, and liver. This will help improve the efficacy of optical coherence tomography in cancer detection and staging in solid organs.

The addition of a sagittal image fusion improves the prostate cancer detection in a sensor-based MRI /ultrasound fusion guided targeted biopsy

BACKGROUND

To explore the diagnostic benefit of an additional image fusion of the sagittal plane in addition to the standard axial image fusion, using a sensor-based MRI/US fusion platform.

METHODS

During July 2013 and September 2015, 251 patients with at least one suspicious lesion on mpMRI (rated by PI-RADS) were included into the analysis. All patients underwent MRI/US targeted biopsy (TB) in combination with a 10 core systematic prostate biopsy (SB). All biopsies were performed on a sensor-based fusion system. Group A included 162 men who received TB by an axial MRI/US image fusion. Group B comprised 89 men in whom the TB was performed with an additional sagittal image fusion.

RESULTS

The median age in group A was 67 years (IQR 61-72) and in group B 68 years (IQR 60-71). The median PSA level in group A was 8.10 ng/ml (IQR 6.05-14) and in group B 8.59 ng/ml (IQR 5.65-12.32). In group A the proportion of patients with a suspicious digital rectal examination (DRE) (14 vs. 29%, p = 0.007) and the proportion of primary biopsies (33 vs 46%, p = 0.046) were significantly lower. The rate of PI-RADS 3 lesions were overrepresented in group A compared to group B (19 vs. 9%; p = 0.044). Classified according to PI-RADS 3, 4 and 5, the detection rates of TB were 42, 48, 75% in group A and 25, 74, 90% in group B. The rate of PCa with a Gleason score ≥7 missed by TB was 33% (18 cases) in group A and 9% (5 cases) in group B; p-value 0.072. An explorative multivariate binary logistic regression analysis revealed that PI-RADS, a suspicious DRE and performing an additional sagittal image fusion were significant predictors for PCa detection in TB. 9 PCa were only detected by TB with sagittal fusion (sTB) and sTB identified 10 additional clinically significant PCa (Gleason ≥7).

CONCLUSION

Performing an additional sagittal image fusion besides the standard axial fusion appears to improve the accuracy of the sensor-based MRI/US fusion platform.

Should Hypoechoic Lesions on Transrectal Ultrasound Be Sampled During Magnetic Resonance Imaging-targeted Prostate Biopsy?

OBJECTIVE

To determine whether supplemental biopsy of hypoechoic ultrasound lesions (HUL) incidentally found during magnetic resonance imaging (MRI)-transrectal ultrasound (TRUS) fusion-targeted prostate biopsy results in improved prostate cancer (PCa) detection.

METHODS

Patients underwent MRI-TRUS-targeted biopsy as part of an ongoing prospective trial from August 2007 to February 2015. For men with HUL, the biopsy pathology of HUL and MRI lesions was classified according to the updated 2014 International Society of Urological Pathology (ISUP) grading system. The detection of PCa by MRI-targeted biopsy with and without HUL biopsy was compared.

RESULTS

Of 1260 men in the trial, 106 underwent biopsy of 119 HULs. PCa was diagnosed in 52 out of 106 men (49%) by biopsy of either MRI lesions or HUL. Biopsy of HUL in addition to MRI lesions resulted in 4 additional diagnoses of high-grade (ISUP grades 3-5) PCa versus biopsy of MRI lesions alone (20 vs 16 men, P = .046). Three of these cases were upgraded from lower grade (ISUP grades 1-2) PCa on MRI-guided biopsy alone, and only 1 case (1% of cohort) was diagnosed that would have been missed by MRI-guided biopsy alone. Supplemental biopsy of HUL did not change the PCa risk category in 96% (102 out of 106) of men with HUL.

CONCLUSION

Supplemental biopsy of HUL yields a small increase in the detection of higher grade PCa as compared with biopsy of MRI lesions alone. As upgrading is rare, routinely screening for HUL during MRI-targeted biopsy remains controversial.

Magnetic Resonance Imaging-Ultrasound Fusion-Guided Prostate Biopsy: Review of Technology, Techniques, and Outcomes

Transrectal ultrasound (TRUS)-guided (12-14 core) systematic biopsy of the prostate is the recommended standard for patients with suspicion of prostate cancer (PCa). Advances in imaging have led to the application of magnetic resonance imaging (MRI) for the detection of PCa with subsequent development of software-based co-registration allowing for the integration of MRI with real-time TRUS during prostate biopsy. A number of fusion-guided methods and platforms are now commercially available with common elements in image and analysis and planning. Implementation of fusion-guided prostate biopsy has now been proven to improve the detection of clinically significant PCa in appropriately selected patients.

Magnetic Resonance Imaging-Transrectal Ultrasound Guided Fusion Biopsy to Detect Progression in Patients with Existing Lesions on Active Surveillance for Low and Intermediate Risk Prostate Cancer

PURPOSE

Active surveillance is an established option for men with low risk prostate cancer. Multiparametric magnetic resonance imaging with magnetic resonance imaging-transrectal ultrasound fusion guided biopsy may better identify patients for active surveillance compared to systematic 12-core biopsy due to improved risk stratification. To our knowledge the performance of multiparametric magnetic resonance imaging in following men on active surveillance with visible lesions is unknown. We evaluated multiparametric magnetic resonance imaging and magnetic resonance imaging-transrectal ultrasound fusion guided biopsy to monitor men on active surveillance.

MATERIALS AND METHODS

This retrospective review included men from 2007 to 2015 with prostate cancer on active surveillance in whom magnetic resonance imaging visible lesions were monitored by multiparametric magnetic resonance imaging and fusion guided biopsy. Progression was defined by ISUP (International Society of Urological Pathology) grade group 1 to 2 and ISUP grade group 2 to 3. Significance was considered at p ≤0.05.

RESULTS

A total of 166 patients on active surveillance with 2 or more fusion guided biopsies were included in analysis. Mean followup was 25.5 months. Of the patients 29.5% had pathological progression. Targeted biopsy alone identified 44.9% of patients who progressed compared to 30.6% identified by systematic 12-core biopsy alone (p = 0.03). Fusion guided biopsy detected 26% more cases of pathological progression on surveillance biopsy compared to systematic 12-core biopsy. Progression on multiparametric magnetic resonance imaging was the sole predictor of pathological progression at surveillance biopsy (p = 0.013). Multiparametric magnetic resonance imaging progression in the entire cohort had 81% negative predictive value, 35% positive predictive value, 77.6% sensitivity and 40.5% specificity in detecting pathological progression.

CONCLUSIONS

Multiparametric magnetic resonance imaging progression predicts the risk of pathological progression. Patients with stable multiparametric magnetic resonance imaging findings have a low rate of progression. Incorporating fusion guided biopsy in active surveillance nearly doubled our detection of pathological progression compared to systematic 12-core biopsy.

Missing the Mark: Prostate Cancer Upgrading by Systematic Biopsy over Magnetic Resonance Imaging/Transrectal Ultrasound Fusion Biopsy

PURPOSE

Multiparametric magnetic resonance imaging and fusion biopsy detect more high risk prostate cancer and less low risk prostate cancer than systematic biopsy. However, there remains a small subset of patients in whom systematic biopsy captures higher grade disease than fusion biopsy. We sought to identify potential mechanisms of the failure of fusion biopsy in the detection of clinically significant prostate cancer.

MATERIALS AND METHODS

We reviewed a prospectively maintained database of patients who underwent multiparametric magnetic resonance imaging followed by fusion biopsy and systematic biopsy from 2007 to 2014. In patients in whom disease was upgraded to clinically significant disease (Gleason 7 or greater) by systematic biopsy over fusion biopsy, independent re-review of magnetic resonance imaging, archived biopsy imaging and whole mount pathology as well as needle coordinate mapping were performed. Multivariate logistic regression analysis was done to determine predictors of upgrading by systematic biopsy.

RESULTS

Disease was upgraded based on systematic biopsy over fusion biopsy in 135 of 1,003 patients (13.5%), of whom only 62 (6.2%) were upgraded to intermediate (Gleason 7) and high risk (Gleason 8 or greater) prostate cancer (51 or 5.1% and 11 or 1.1%, respectively). On multivariate analysis lower prostate specific antigen (p <0.001), higher magnetic resonance imaging prostate volume (p <0.001) and a lower number of target cores (p = 0.001) were predictors of upgrading by systematic biopsy. Main mechanisms of under grading by fusion biopsy included multiparametric magnetic resonance imaging reader oversight, presence of magnetic resonance imaging invisible cancer, fusion biopsy technique error and intralesion Gleason heterogeneity.

CONCLUSIONS

Magnetic resonance imaging and fusion biopsy rarely missed clinically significant prostate cancer as only 62 of 1,003 cases (6.2%) were upgraded to clinically significant disease by systematic biopsy. Imaging and biopsy techniques are continually refined. Further studies will help clarify mechanisms of fusion biopsy failure and the patient populations that benefit from systematic biopsy in addition to fusion biopsy.

Risk stratification of prostate cancer utilizing apparent diffusion coefficient value and lesion volume on multiparametric MRI

PURPOSE

To evaluate the performance of apparent diffusion coefficient (ADC) and lesion volume in potentially risk-stratifying patients with prostate cancer (PCa).

MATERIALS AND METHODS

Men with elevated prostate-specific antigen or abnormal digital rectal exam underwent a 3T multiparametric magnetic resonance imaging (mpMRI) with endorectal coil. ADC maps were calculated using b values of 0, 500, 1000, and 1500; additional images were obtained with b value of 2000. We prospectively enrolled 312 men with lesions suspicious for cancer (suspicion score 2-5) on mpMRI. MRI/ultrasound fusion-guided prostate biopsies were performed. Mean ADC of suspicious lesions were correlated against lesion volume, Gleason and D'Amico risk.

RESULTS

The cancer detection rate of fusion biopsy per lesion was 45.6% (206/452). Cancerous lesions were larger (median volume: 0.40 vs. 0.30 cm³ ; P = 0.016). The median ADC (×10^-6 mm² /sec) for lesions negative and positive for PCa were 984.5 and 666.5, respectively (P < 0.0001). The AUC of ADC in predicting PCa was 0.79. Larger lesions were associated with higher risk PCa (Gleason and D'Amico) and lower ADC (all P < 0.0001).

CONCLUSION

The mean ADC of suspicious lesions on mpMRI was inversely correlated, while lesion volume had a direct correlation with PCa detection. Future follow-up studies are needed to assess longitudinal cancer risks of suspicious mpMRI lesions.

LEVEL OF EVIDENCE

2 J. Magn. Reson. Imaging 2017;45:610-616.

A practical approach to investigating a man with a raised prostate-specific antigen in the modern era

Urologists in the UK are encouraged to follow the National Institute for Health and Care Excellence (NICE) guidelines for patient management. In 2014, members of the British Association of Urological Surgeons (BAUS) were asked in a survey what diagnostic pathway they would follow for themselves or their relatives if they had a raised prostate-specific antigen (PSA). It was found that only a quarter would follow NICE guidance. The current recommendations rely on pathological assessment of prostate tissue obtained at a transrectal ultrasound guided biopsy. Increasing evidence indicates that pre-biopsy multiparametric magnetic resonance imaging (mp-MRI) coupled with targeted biopsy approaches outperform random biopsies in the detection of clinically significant disease. Herein we discuss the role of magnetic resonance imaging and targeted biopsy approaches to diagnose prostate cancer in the modern era.

Integrating MRI for the diagnosis of prostate cancer

PURPOSE OF REVIEW

We review recent developments in prostate MRI for prostate cancer diagnosis.

RECENT FINDINGS

Large series have strengthened the case for the use of MRI prior to subsequent biopsy to maximize the detection of clinically significant disease, and reduce the detection of clinically insignificant disease. This has effectively moved the discussion on from whether MRI is useful in prostate cancer detection to how best to use it, and at which time point. The Prostate Imaging- Reporting And Data System (PIRADS) group have published a second version of the PIRADS criteria for prostate MRI, covering acquisition, interpretation, and reporting both for clinical practice and data collection for research.There is debate about the commonly used and more prescriptive PIRADS system versus the less prescriptive systems based on overall clinical impression of clinically significant disease (e.g. Likert or simplified quantum scoring). Studies suggest that the Likert or simplified quantum scoring approach may outperform PIRADSv2. Published data are conflicting on whether software-assisted fusion of MRI lesions to ultrasound used at biopsy is more effective than visual registration by a trained operator.

SUMMARY

The use of prostate MRI is increasing worldwide, and the debate now focuses on how best to use it to optimize the detection of clinically significant disease.

Midline lesions of the prostate: role of MRI/TRUS fusion biopsy and implications in Gleason risk stratification

PURPOSE

MRI-TRUS fusion biopsy (FBx) has proven efficacy in targeting suspicious areas that are traditionally missed by systematic 12-core biopsy (SBx). Midline prostate lesions are undersampled during SBx, as traditional approaches aim laterally during TRUS biopsy. The aim of our study was to determine the utility of FBx for targeting midline lesions identified on multiparametric MRI (mpMRI).

METHODS

A review was performed of a prospectively maintained database of patients undergoing mpMRI followed by FBx and SBx from 2007 to 2015. Midline location was defined as any lesion crossing the midline on axial imaging and involving both prostatic lobes. Index lesion was defined as lesion with highest Gleason score on biopsy. Patient demographic, imaging, and histopathologic data were collected. Multivariate logistic regression was conducted to determine independent predictors of having clinically significant (CS) cancer (Gleason ≥ 7) in midline lesions.

RESULTS

Out of 1266 patients, we identified 202 suspicious midline lesions in 190 patients [median (IQR) age 63 (10) years; PSA 7.6 (6.6)]. Eighty-eight (46.3 %) patients had cancer detection on FBx of midline lesion. A midline target represented the index lesion of the prostate in 63/190 (33.2 %) patients. Risk category upgrading based on FBx of a midline lesion compared to SBx occurred in 45/190 patients (23.7 %). On multivariate analysis, higher PSA (p = .001), lower MRI-derived prostate volume (p < .001), and moderate-high or high suspicion on mpMRI (p = .014) predicted CS cancer in midline lesions.

CONCLUSIONS

MRI-TRUS FBx facilitates sampling of midline lesions. Integration of mpMRI and FBx for targeting of midline lesions improves detection of CS prostate cancer.

Nanotechnology and cancer: improving real-time monitoring and staging of bladder cancer with multimodal mesoporous silica nanoparticles

Background

Despite being one of the most common cancers, bladder cancer is largely inefficiently and inaccurately staged and monitored. Current imaging methods detect cancer only when it has reached “visible” size and has significantly disrupted the structure of the organ. By that time, thousands of cells will have proliferated and perhaps metastasized. Repeated biopsies and scans are necessary to determine the effect of therapy on cancer growth. In this report, we describe a novel approach based on multimodal nanoparticle contrast agent technology and its application to a preclinical animal model of bladder cancer. The innovation relies on the engineering core of mesoporous silica with specific scanning contrast properties and surface modification that include fluorescence and magnetic resonance imaging (MRI) contrast. The overall dimensions of the nano-device are preset at 80–180 nm, depending on composition with a pore size of 2 nm.

Methods

To facilitate and expedite discoveries, we combined a well-known model of bladder cancer and our novel technology. We exposed nanoparticles to MB49 murine bladder cancer cells in vitro and found that 70 % of the cells were labeled by nanoparticles as measured by flow cytometry. The in vivo mouse model for bladder cancer is particularly well suited for T1- and T2-weighted MRI.

Results

Under our experimental conditions, we demonstrate that the nanoparticles considerably improve tumor definition in terms of volumetric, intensity and structural characteristics. Important bladder tumor parameters can be ascertained, non-invasively, repetitively, and with great accuracy. Furthermore, since the particles are not biodegradable, repetitive injection is not required. This feature allows follow-up diagnostic evaluations during cancer treatment. Changes in MRI signals show that in situ uptake of free particles has predilection to tumor cells relative to normal bladder epithelium. The particle distribution within the tumors was corroborated by fluorescent microscopy of sections of excised bladders. In addition, MRI imaging revealed fibrous finger-like projections into the tumors where particles insinuated themselves deeply. This morphological characteristic was confirmed by fluorescence microscopy.

Conclusions

These findings may present new options for therapeutic intervention. Ultimately, the combination of real-time and repeated MRI evaluation of the tumors enhanced by nanoparticle contrast may have the potential for translation into human clinical studies for tumor staging, therapeutic monitoring, and drug delivery.

The role of MRI in active surveillance for prostate cancer

Approximately one in seven American men will be diagnosed with prostate cancer during his lifetime, and at least 50% of newly diagnosed patients will present with low-risk disease. In the last decade, the decision-making paradigm for management has shifted due to high rates of disease detection and overtreatment, attributed to prostate-specific antigen screening, with more men deferring definitive treatment for active surveillance. The advent of multiparametric magnetic resonance imaging (MP-MRI) and MRI/ transrectal ultrasound-guided fusion-guided prostate biopsy has refined the process of diagnosis, identifying patients with clinically-significant cancer and larger disease burden who would most likely benefit from intervention. In parallel, the utilization of MP-MRI in the surveillance of low-grade, low-volume disease is on the rise, reflecting support in a growing body of literature. The aim of this review is to appraise and summarize the data evaluating the role of magnetic resonance imaging in active surveillance for prostate cancer.

Optimizing Patient Population for MP-MRI and Fusion Biopsy for Prostate Cancer Detection

The diagnosis and treatment of prostate cancer continue to evolve with advances in science and technology. The utilization of multiparametric MRI (mp-MRI) to identify lesions in the prostate has given clinicians the ability to visualize malignancy in the prostate with greater confidence. With this new ability came the advancement of fusion biopsy platforms, which allow for direct targeting of these lesions. As with any new technology in medicine, the proper use of these modalities and how they fit into current clinical practice need to be addressed. This review summarizes the current knowledge on how to best optimize which men undergo mp-MRI and fusion biopsies both in the screening and treatment settings.

The significance of anterior prostate lesions on multiparametric magnetic resonance imaging in African-American men

INTRODUCTION

African-American (AA) men tend to harbor high-risk prostate cancer (PCa) and exhibit worse outcomes when compared to other groups. It has been postulated that AA men may harbor more anterior prostate lesions (APLs) that are undersampled by the standard transrectal ultrasound guided-biopsy (SBx), potentially resulting in greater degree of Gleason score (GS) upgrading at radical prostatectomy. We aimed to evaluate the detection rate of anterior PCa significance of APLs in AA men on multiparametric magnetic resonance imaging (mpMRI) and compare it to a matched cohort of White/Other (W/O) men.

MATERIALS AND METHODS

A review of 1,267 men who had an mpMRI with suspicious prostate lesions and who underwent magnetic resonance transrectal ultrasound fusion-guided biopsy (FBx) with concurrent SBx in the same biopsy session was performed. All AA men were matched to a control group of W/O using a 1:1 propensity score-matching algorithm with age, prostate-specific antigen, and prostate volume as matching variables. Logistic regression analysis was used to determine predictors of APLs in AA men.

RESULTS

Of the 195 AA men who underwent mpMRI, 93 (47.7%) men had a total of 109 APLs. Prior negative SBx was associated with the presence of APLs in AA men (Odds ratio = 1.81; 95% CI: 1.03-3.20; P = 0.04). On multivariate logistic regression analysis, smaller prostate (P = 0.001) and rising prostate-specific antigen (P = 0.007) were independent predictors of cancer-positive APLs in AA men. Comparative analysis of AA (93/195, 47.7%) vs. W/O (100/194, 52%) showed no difference in the rates of APLs (P = 0.44) or in cancer detection rate within those lesions or the distribution of GS within those cancers (P = 0.63) despite an overall higher cancer detection rate in AA men (AA: 124/195 [63.6%] vs. W/O: 97/194 [50.0%], P = 0.007). In cases where APLs were positive for PCa on FBx, the GS of APL was equal to the highest GS of the entire gland in 82.9% (29/35) and 90.9% (30/33) of the time in AA and W/O men, respectively.

CONCLUSION

Cancer-positive APLs represented the highest risk GS in most cases. AA men with prior negative SBx are twice as likely to harbor a concerning APL. In our cohort, AA and W/O men had comparable rates of APLs on mpMRI. Thus, differences in APLs do not explain the higher risk of AA men for deahth due to PCa. However, targeting of APLs via FBx can clinically improve PCa risk stratification and guide appropriate treatment options.

Prostate Cancer Diagnosis on Repeat Magnetic Resonance Imaging-Transrectal Ultrasound Fusion Biopsy of Benign Lesions: Recommendations for Repeat Sampling

PURPOSE

Urologists face a dilemma when a lesion identified on multiparametric magnetic resonance imaging is benign on image guided fusion biopsy. We investigated the detection rate of prostate cancer on repeat fusion biopsy in multiparametric magnetic resonance imaging lesions initially found to be pathologically benign on fusion biopsy.

MATERIALS AND METHODS

We reviewed the records of all patients from 2007 to 2014 who underwent multiparametric magnetic resonance imaging and image guided fusion biopsy. We identified men who underwent rebiopsy of the same discrete lesion after initial fusion biopsy results were benign. Data were documented on a per lesion basis. We manually reviewed UroNav system (Invivo, Gainesville, Florida) needle tracking to verify accurate image registration. Multivariate analysis was used to identify clinical and imaging factors predictive of prostate cancer detection at repeat fusion biopsy.

RESULTS

A total of 131 unique lesions were rebiopsied in 90 patients. Of these 131 resampled lesions 21 (16%) showed prostate cancer, which in 13 (61.9%) was Gleason 3 + 3. On multivariate analysis only lesion growth on repeat multiparametric magnetic resonance imaging was significantly associated with prostate cancer detection at repeat biopsy (HR 3.274, 95% CI 1.205-8.896, p = 0.02).

CONCLUSIONS

Pathologically benign multiparametric magnetic resonance imaging lesions on initial image guided fusion biopsy are rarely found to harbor clinically significant prostate cancer on repeat biopsy. When prostate cancer was identified, most disease was low risk. An increase in lesion diameter was an independent predictor of prostate cancer detection. While these data are retrospective, they may provide some confidence in the reliability of negative initial image guided fusion biopsies despite a positive multiparametric magnetic resonance imaging finding.

Reproducibility of Multiparametric Magnetic Resonance Imaging and Fusion Guided Prostate Biopsy: Multi-Institutional External Validation by a Propensity Score Matched Cohort

PURPOSE

As the adoption of magnetic resonance imaging/ultrasound fusion guided biopsy expands, the reproducibility of outcomes at expert centers becomes essential. We sought to validate the comprehensive NCI (National Cancer Institute) experience with multiparametric magnetic resonance imaging and fusion guided biopsy in an external, independent, matched cohort of patients.

MATERIALS AND METHODS

We compared 620 patients enrolled in a prospective trial comparing systematic biopsy to fusion guided biopsy at NCI to 310 who underwent a similar procedure at Long Island Jewish Medical Center. The propensity score, defined as the probability of being treated outside NCI, was calculated using the estimated logistic regression model. Patients from the hospital were matched 1:1 for age, prostate specific antigen, magnetic resonance imaging suspicion score and prior negative biopsies. Clinically significant disease was defined as Gleason 3 + 4 or greater.

RESULTS

Before matching we found differences between the cohorts in age, magnetic resonance imaging suspicion score (each p <0.001), the number of patients with prior negative biopsies (p = 0.01), and the overall cancer detection rate and the cancer detection rate by fusion guided biopsy (each p <0.001). No difference was found in the rates of upgrading by fusion guided biopsy (p = 0.28) or upgrading to clinically significant disease (p = 0.95). A statistically significant difference remained in the overall cancer detection rate and the rate by fusion guided biopsy after matching. On subgroup analysis we found a difference in the overall cancer detection rate and the rate by fusion guided biopsy (p <0.001 and 0.003) in patients with prior negative systematic biopsy but no difference in the 2 rates (p = 0.39 and 0.51, respectively) in biopsy naïve patients.

CONCLUSIONS

Improved detection of clinically significant cancer by magnetic resonance imaging and fusion guided biopsy is reproducible by an experienced multidisciplinary team consisting of dedicated radiologists and urologists.

Combined Biparametric Prostate Magnetic Resonance Imaging and Prostate-specific Antigen in the Detection of Prostate Cancer: A Validation Study in a Biopsy-naive Patient Population

OBJECTIVE

To validate the use of biparametric (T2- and diffusion-weighted) magnetic resonance imaging (B-MRI) and prostate-specific antigen (PSA) or PSA density (PSAD) in a biopsy-naive cohort at risk for prostate cancer (PCa).

METHODS

All patients (n = 59) underwent PSA screening and digital rectal exam prior to a B-MRI followed by MRI or transrectal ultrasound fusion-guided targeted biopsy. Previously reported composite formulas incorporating screen positive lesions (SPL) on B-MRI and PSA or PSAD were developed to maximize PCa detection. For PSA, a patient was considered screen positive if PSA level + 6 × (the number of SPL) >14. For PSAD, screening was positive if PSAD × 14 + (the number of SPL) >4.25. These schemes were employed in this new test set to validate the initial formulas. Performance assessment of these formulas was determined for all cancer detection and for tumors with Gleason ≥3 + 4.

RESULTS

Screen positive lesions on B-MRI had the highest sensitivity (95.5%) and negative predictive value of 71.4% compared with PSA and PSAD. B-MRI significantly improved sensitivity (43.2-72.7%, P = .0002) when combined with PSAD. The negative predictive value of PSA increased with B-MRI, achieving 91.7% for B-MRI and PSA for Gleason ≥3 + 4. Overall accuracies of the composite equations were 81.4% (B-MRI and PSA) and 78.0% (B-MRI and PSAD).

CONCLUSION

Validation with a biopsy-naive cohort demonstrates the parameter SPL performed better than PSA or PSAD alone in accurately detecting PCa. The combined use of B-MRI, PSA, and PSAD resulted in improved accuracy for detecting clinically significant PCa.

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.

Magnetic Resonance Imaging/Transrectal Ultrasonography Fusion Prostate Biopsy Significantly Outperforms Systematic 12-Core Biopsy for Prediction of Total Magnetic Resonance Imaging Tumor Volume in Active Surveillance Patients

OBJECTIVE

To correlate the highest percentage core involvement (HPCI) and corresponding tumor length (CTL) on systematic 12-core biopsy (SBx) and targeted magnetic resonance imaging/transrectal ultrasonography (MRI/TRUS) fusion biopsy (TBx), with total MRI prostate cancer (PCa) tumor volume (TV).

PATIENTS AND METHODS

Fifty patients meeting criteria for active surveillance (AS) based on outside SBx, who underwent 3.0T multiparametric prostate MRI (MP-MRI), followed by SBx and TBx during the same session at our institution were examined. PCa TVs were calculated using MP-MRI and then correlated using bivariate analysis with the HPCI and CTL for SBx and TBx.

RESULTS

For TBx, HPCI and CTL showed a positive correlation (R(2)=0.31, P<0.0001 and R(2)=0.37, P<0.0001, respectively) with total MRI PCa TV, whereas for SBx, these parameters showed a poor correlation (R(2)=0.00006, P=0.96 and R(2)=0.0004, P=0.89, respectively). For detection of patients with clinically significant MRI derived tumor burden greater than 500 mm(3), SBx was 25% sensitive, 90.9% specific (falsely elevated because of missed tumors and extremely low sensitivity), and 54% accurate in comparison with TBx, which was 53.6% sensitive, 86.4% specific, and 68% accurate.

CONCLUSIONS

HPCI and CTL on TBx positively correlates with total MRI PCa TV, whereas there was no correlation seen with SBx. TBx is superior to SBx for detecting tumor burden greater than 500 mm(3). When using biopsy positive MRI derived TVs, TBx better reflects overall disease burden, improving risk stratification among candidates for active surveillance.

Prostate Cancer: Interobserver Agreement and Accuracy with the Revised Prostate Imaging Reporting and Data System at Multiparametric MR Imaging

PURPOSE

To evaluate accuracy and interobserver variability with the use of the Prostate Imaging Reporting and Data System (PI-RADS) version 2.0 for detection of prostate cancer at multiparametric magnetic resonance (MR) imaging in a biopsy-naïve patient population.

MATERIALS AND METHODS

This retrospective HIPAA-compliant study was approved by the local ethics committee, and written informed consent was obtained from all patients for use of their imaging and histopathologic data in future research studies. In 101 biopsy-naïve patients with elevated prostate-specific antigen levels who underwent multiparametric MR imaging of the prostate and subsequent transrectal ultrasonography (US)-MR imaging fusion-guided biopsy, suspicious lesions detected at multiparametric MR imaging were scored by five readers who were blinded to pathologic results by using to the newly revised PI-RADS and the scoring system developed in-house. Interobserver agreement was evaluated by using κ statistics, and the correlation of pathologic results with each of the two scoring systems was evaluated by using the Kendall τ correlation coefficient.

RESULTS

Specimens of 162 lesions in 94 patients were sampled by means of transrectal US-MR imaging fusion biopsy. Results for 87 (54%) lesions were positive for prostate cancer. Kendall τ values with the PI-RADS and the in-house-developed scoring system, respectively, at T2-weighted MR imaging in the peripheral zone were 0.51 and 0.17 and in the transitional zone, 0.45 and -0.11; at diffusion-weighted MR imaging, 0.42 and 0.28; at dynamic contrast material-enhanced MR imaging, 0.23 and 0.24, and overall suspicion scores were 0.42 and 0.49. Median κ scores among all possible pairs of readers for PI-RADS and the in-house-developed scoring system, respectively, for T2-weighted MR images in the peripheral zone were 0.47 and 0.15; transitional zone, 0.37 and 0.07; diffusion-weighted MR imaging, 0.41 and 0.57; dynamic contrast-enhanced MR imaging, 0.48 and 0.41; and overall suspicion scores, 0.46 and 0.55.

CONCLUSION

Use of the revised PI-RADS provides moderately reproducible MR imaging scores for detection of clinically relevant disease.

The Role of Magnetic Resonance Image Guided Prostate Biopsy in Stratifying Men for Risk of Extracapsular Extension at Radical Prostatectomy

PURPOSE

Magnetic resonance imaging detects extracapsular extension by prostate cancer with excellent specificity but low sensitivity. This limits surgical planning, which could be modified to account for focal extracapsular extension with image directed guidance for wider excision. In this study we evaluate the performance of multiparametric magnetic resonance imaging in extracapsular extension detection and determine which preoperative variables predict extracapsular extension on final pathology when multiparametric magnetic resonance imaging predicts organ confined disease.

MATERIALS AND METHODS

From May 2007 to March 2014, 169 patients underwent pre-biopsy multiparametric magnetic resonance imaging, magnetic resonance imaging/transrectal ultrasound fusion guided biopsy, extended sextant 12-core biopsy and radical prostatectomy at our institution. A subset of 116 men had multiparametric magnetic resonance imaging negative for extracapsular extension and were included in the final analysis.

RESULTS

The 116 men with multiparametric magnetic resonance imaging negative for extracapsular extension had a median age of 61 years (IQR 57-66) and a median prostate specific antigen of 5.51 ng/ml (IQR 3.91-9.07). The prevalence of extracapsular extension was 23.1% in the overall population. Sensitivity, specificity, and positive and negative predictive values of multiparametric magnetic resonance imaging for extracapsular extension were 48.7%, 73.9%, 35.9% and 82.8%, respectively. On multivariate regression analysis only patient age (p=0.002) and magnetic resonance imaging/transrectal ultrasound fusion guided biopsy Gleason score (p=0.032) were independent predictors of extracapsular extension on final radical prostatectomy pathology.

CONCLUSIONS

Because of the low sensitivity of multiparametric magnetic resonance imaging for extracapsular extension, further tools are necessary to stratify men at risk for occult extracapsular extension that would otherwise only become apparent on final pathology. Magnetic resonance imaging/transrectal ultrasound fusion guided biopsy Gleason score can help identify which men with prostate cancer have extracapsular extension that may not be detectable by imaging.

Multiparametric MRI in the PSA screening era

Prostate cancer remains significant public health concern amid growing controversies regarding prostate specific antigen (PSA) based screening. The utility of PSA has been brought into question, and alternative measures are investigated to remedy the overdetection of indolent disease and safeguard patients from the potential harms resulting from an elevated PSA. Multiparametric MRI of the prostate has shown promise in identifying patients at risk for clinically significant disease but its role within the current diagnostic and treatment paradigm remains in question. The current review focuses on recent applications of MRI in this pathway.