Targeted MRI/TRUS fusion-guided biopsy in men with previous prostate biopsies using a novel registration software and multiparametric MRI PI-RADS scores: first results

Variability of mpMRI diagnostic performance according to the upfront individual patient risk of having clinically significant prostate cancer

BACKGROUND

To assess the variation of multiparametric magnetic resonance imaging (mpMRI) positive predictive value (PPV) according to each patient's risk of clinically significant prostate cancer (csPCa) based exclusively on clinical factors.

METHODS

We evaluated 999 patients with positive mpMRI (PI-RADS ≥ 3) receiving targeted (TBx) plus systematic prostate biopsy. We built a multivariable logistic regression analysis (MVA) using clinical risk factors to calculate the individual patients' risk of harboring csPCa at TBx. A second MVA tested the association between individual patients' clinical risk and mpMRI PPV accounting for the PI-RADS score. Finally, we plotted the PPV of each PI-RADS score by the individual patient pretest probability of csPCa using a LOWESS approach.

RESULTS

Overall, TBx found csPCa in 21%, 51%, and 80% of patients with PI-RADS 3, 4, and 5 lesions, respectively. At MVA, age, PSA, digital rectal examination (DRE), and prostate volume were significantly associated with the risk of csPCa at biopsy. DRE yielded the highest odds ratio (OR: 2.88; p < 0.001). The individual patient's clinical risk was significantly associated with mpMRI PPV (OR: 2.49; p < 0.001) using MVA. Plotting the mpMRI PPV according to the predicted clinical risks, we observed that for patients with clinical risk close to 0 versus patients with risk higher than 90%, the mpMRI PPV of PI-RADS 3, 4, and 5 ranged from 0% to 75%, from 0% to 96%, and from 45% to 100%, respectively.

CONCLUSION

mpMRI PPV varies according to the individual pretest patient's risk based on clinical factors. These findings should be considered in the decision-making process for patients with suspect MRI findings referred for a prostate biopsy. Moreover, our data support the need for further studies to create an individualized risk prediction tool.

Impact of the time elapsed between prostate biopsy and surgery on the accuracy of nomograms predicting lymph node invasion in patients with clinically localized prostate cancer

We aimed to investigate whether the performance characteristics of available nomograms predicting lymph node invasion (LNI) in prostate cancer patients undergoing radical prostatectomy (RP) change according to the time elapsed between diagnosis and surgery. We identified 816 patients who underwent RP with extended pelvic lymph node dissection (ePLND) after combined prostate biopsy at 6 referral centers. We plotted the accuracy (ROC-derived area under the curve [AUC]) of each Briganti nomogram according to the time elapsed between biopsy ad RP. We then tested whether discrimination of the nomograms improved after accounting for the time elapsed between biopsy ad RP. The median time between biopsy and RP was 3 months. The LNI rate was 13%. The discrimination of each nomogram decreased with increasing time elapsed between biopsy and surgery, where the AUC of the 2019 Briganti nomogram was 88% vs. 70% for men undergoing surgery <2 vs. >6 months from the biopsy. The addition of the time elapsed between biopsy ad RP improved the accuracy of all available nomograms (P < 0.003), with the Briganti 2019 nomogram showing the highest discrimination. Clinicians should be aware that the discrimination of available nomograms decreases according to the time elapsed between diagnosis and surgery. The indication of ePLND should be carefully evaluated in men below the LNI cut-off who had a diagnosis more than 6 months before RP. This has important implications when considering the longer waiting lists related to the impact of COVID-19 on healthcare systems.

Assessing the need for systematic biopsies in addition to targeted biopsies according to the characteristics of the index lesion at mpMRI. Results from a large, multi-institutional database

PURPOSE

We hypothesized that systematic biopsies (SBx) value for clinically significant PCa (csPCa) detection, in addition to mpMRI targeted biopsies (TBx), may vary significantly according to mpMRI index lesion (IL) characteristics.

METHODS

We identified 1350 men with an mpMRI suspicious lesion (PI-RADS ≥ 3), defined as IL, who underwent TBx and SBx at three referral centres. The outcome was SBx added value in csPCa (grade group ≥ 2 PCa detected at SBx and missed by TBx) detection. To this aim, we performed multivariable logistic regression analyses (MVA). Furthermore, we explored the interaction between IL volume and SBx csPCa added value, across different PI-RADS categories, using lowess function.

RESULTS

Overall, 569 (42%) men had csPCa at TBx and 78 (6%) csPCa were identified at SBx only. At MVA PSA (OR 0.90; p < 0.05) and IL volume (OR 0.58; p < 0.05) were associated with SBx csPCa added value. At interaction analyses, a nonlinear correlation between PI-RADS and SBx csPCa added value was identified with a decrease from roughly 10 to 4% followed by a substantial plateau at 1.2 ml and 0.6 ml for PI-RADS 3 and 4, respectively. For PI-RADS 5 lesions SBx csPCa added was constantly lower than 4%.

CONCLUSIONS

Increasing IL volume in PI-RADS 3 and 4 lesions is associated with reduction in SBx csPCa added value. For diagnostic purposes, SBx could be omitted in men with IL larger than 1.2 ml and 0.6 ml for PI-RADS 3 and 4, respectively. Conversely, for PI-RADS 5, SBx csPCa added value was minimal regardless of IL volume.

Does previous prostate surgery affect multiparametric magnetic resonance imaging accuracy in detecting clinically significant prostate cancer? Results from a single institution series

BACKGROUND

Multiparametric MRI (mpMRI) has demonstrated high diagnostic accuracy for clinically significant PCa (csPCa). However, the accuracy of this test in men that received a previous prostatic surgery is still controversial. We aimed at assessing the effect of previous prostatic surgery on the detection of csPCa in a tertiary referral center.

METHOD

We relied on a cohort of 311 men with a positive mpMRI (prostate imaging - reporting and data system [PI-RADS] ≥ 3) who underwent a targeted (TBx) plus concomitant systematic random biopsy (SBx) at a single tertiary referral center between 2017 and 2020. The study outcome was to compare the detection of csPCa (Gleason score ≥ 3 + 4) between the two groups (no previous prostate surgery [Group 1] vs. previous prostate surgery [Group 2]). Multivariable logistic regression analysis (MVA) was used to assess the relationship between previous prostate surgery and the detection of csPCa at TBx, after taking into account potential clinical confounders.

RESULTS

Overall, 24 (8%) patients received a previous prostate surgery before undergoing mpMRI. Median prostate-specific antigen density was 0.15 versus 0.08 ng/ml/cc, in Group 1 versus 2, respectively. The most frequent finding at mpMRI was in Group 1 versus 2, PI-RADS 4 (55%) versus PI-RADS 3 and 4 (42% each). The majority of patients were biopsy naïve in both Groups 1 (66%) and 2 (71%). The overall detection of csPCa in Group 1 versus 2 was 83% versus 75%, respectively. Differently, the detection of csPCa at TBx in Groups 1 versus 2 was 76% versus 71%, respectively. At MVA, previous prostate surgery (odds ratio: 0.65; p = 0.02) was significantly associated with lower csPCa detection at TBx, after accounting for potential confounders.

CONCLUSION

The presence of previous prostate surgery significantly decreases the accuracy of mpMRI in detecting csPCa. These results should be taken into account when assessing patients with a history of prostatic surgery and a suspicious lesion at mpMRI, to better select those who might avoid an unnecessary biopsy.

Application of Multiple Ultrasonic Techniques in the Diagnosis of Prostate Cancer

Methods for diagnosing prostate cancer (PCa) are developing in the direction of imaging. Advanced ultrasound examination modes include micro-Doppler, computerized-transrectal ultrasound, elastography, contrast-enhanced ultrasound and microultrasound. When two or more of these modes are used in PCa diagnosis, the combined technique is called multiparameter ultrasound (mp-US). Mp-US provides complementary information to multiparameter magnetic resonance imaging (mp-MRI) for diagnosing PCa. At present, no study has attempted to combine the characteristics of different ultrasound modes with advanced classification systems similar to the PIRADS system in mpMRI for the diagnosis of PCa. As an imaging method, mp-US has great potential in the diagnosis of PCa.

First experiences and results after cryoablation of prostate cancer with histopathological evaluation and imaging-based follow-up

Aim: To share our experience after 28 cryoablation treatments for prostate cancer (PCa) with histopathology, clinical data and MRI as the follow-up methods. Methods: Clinical follow-up comprised prostate specific antigen (PSA)-measurements, PSA-density and quality-of-life-parameters. multi-parametric (mp)MRI pre- and post-cryoablation were retrospectively re-analyzed in 23 cases using Likert scores. Follow-up-histopathology was performed via MRI/ultrasound fusion-guided and/or systematic biopsy. Receiver operating characteristic curve analysis was performed. Results: 17 PCa (61%) were diagnosed within 12-month post-cryotherapy (infield and out-of-field disease). PSA levels and PSA density were not significantly different between patients with or without PCa recurrence. mpMRI can characterize the decrease in prostate volume and necrosis. Area under the curve for the detection of PCa was 81% (global Likert scores), 74-87% (T2), 78% (diffusion weighted imaging) and 57-78% (dynamic contrast enhanced imaging; Youden-selected cutoff ≥3). Conclusion: Besides histopathological evaluation and control biopsy, MRI might have the potential to accurately detect PCa after cryotherapy. Clinical data and interdisciplinary communication are required for efficient monitoring after cryoablation treatments for PCa.

Diagnostic performance of fusion (US/MRI guided) prostate biopsy: propensity score matched comparison of elastic versus rigid fusion system

PURPOSE

Many software for US/MRI guided fusion prostate biopsy (FPB), have been developed in the last years. However, there are few data comparing diagnostic accuracy of different fusion systems. We assessed diagnostic performance of elastic (EF) versus rigid fusion (RF) PB in a propensity score matched (PSM) analysis.

METHODS

A total of 314 FPB were prospectively collected from two different centers. All patients were biopsy naïve and all mpMRI reported a single suspicious area. Overall, 211 PB were performed using a RF system and 103 using an EF software. The two groups were compared for the main clinical features. A 1:1 PSM analysis was employed to reduce covariate imbalance to < 10%. Detection rate (DR) for any prostate cancer (PCa) and clinically significant (cs) PCa were compared and stratified for PI-RADS Score. A per target univariable and multivariable regression analyses were applied to identity predictors of anyPCa and csPCa.

RESULTS

After applying the PSM, two cohorts of 83 cases were selected. DR of any PCa cancer and csPCa were comparable between the two cohorts (all p > 0.077) as well as DR of csPCa for every PIRADS score. At univariable regression analysis lesion size, PI-RADS Score, PSA Density and EF system were predictors of any PCa (all p < 0.001); however, at multivariable analysis only PI-RADS Score was independent predictor of any PCa (p = 0.027). At multivariable analysis only PI-RADS score was independent predictor of csPCa.

CONCLUSIONS

Fusion PB guarantees high diagnostic accuracy for csPCa, regardless of the fusion technology. Prospective randomized study is needed to confirm these data.

Optimizing prostate-targeted biopsy schemes in men with multiple mpMRI visible lesions: should we target all suspicious areas? Results of a two institution series

BACKGROUND

To assess the diagnostic added value of sampling secondary lesions at prostate mpMRI (SL) in addition to index lesion (IL) in detecting significant prostate cancer (csPCa) when also systematic biopsy (SBx) is performed.

METHODS

We relied on a cohort of 312 men with two suspicious lesions at prostate mpMRI who underwent subsequent targeted biopsy of each lesion (TBx) and concomitant SBx at two tertiary-referral centers between 2013 and 2019. The study outcome was the added value of targeting SL (i.e., the one with a lower PI-RADS score and/or the smaller size compared to IL) in the detection of csPCa. To this aim, we compared different biopsy strategies (SBx + overall TBx vs SBx + IL-targeted biopsy vs SBx + SL-targeted biopsy) and assessed whether SL features could be correlated with detection of csPCa at overall TBx in a multivariable logistic regression model (MVA).

RESULTS

Overall, 44% of men had csPCa at TBx of all lesions while 39% and 23% of men had csPCa found in IL and SL, respectively. The rate of csPCa found at SBx, IL-TBx, and SL-TBx only was 5%, 6%, and 2%, respectively. The detection rate of csPCa for SBx + IL-TBx was 47%. The addition of SL-TBx increased csPCa detection by only 2% (p = 0.12). At MVA, neither PI-RADS of SL nor the number of cores targeting SL was associated with an increased detection of csPCa (all p > 0.3). Conversely, age (OR: 1.07), PSA (OR: 1.07), prostate volume (OR: 0.98), and PI-RADS of the IL (OR: 2.36) were independently associated with csPCa detection at TBx (all p < 0.01).

CONCLUSIONS

There is no significant benefit in terms of csPCa detection when an adequate SBx is performed in combination with IL-TBx in patients with multiple mpMRI lesions. In these men target biopsy of secondary lesions can be safely omitted.

How to optimize follow-up in patients with a suspicious multiparametric MRI and a subsequent negative targeted prostate biopsy. Results from a large, single-institution series

OBJECTIVE

We aimed at optimizing the follow-up for patients with a positive multiparametric magnetic resonance of the prostate (mpMRI) and a subsequent negative targeted biopsy (TBx) plus systematic biopsy (SBx).

MATERIALS AND METHODS

A total of 308 men with a clinical suspicion of PCa and a positive mpMRI (PI-RADS ≥ 3) with concomitant negative systematic and targeted Bx performed at a single tertiary referral center. All patients were then followed with serial PSA measurements, digital rectal examination and eventual follow-up mpMRI and/or repeat Bx. The primary outcome was to evaluate the overall clinically significant PCa (csPCa)-free survival. The secondary outcome was to assess the role of a repeat mpMRI (Fu-mpMRI) and PSA density as predictors of csPCa diagnosis (defined as Gleason score ≥ 3 + 4) during follow-up. Kaplan Meier analysis and univariable Cox regression were used for survival and predictive analyses.

RESULTS

Median follow-up was 31 months (IQR: 23-43). During the study period 116 (37.7%) and 68 (22.1%) of men received a Fu-mpMRI and a Fu-Bx, respectively. Overall, 51 (16.6%) and 15 (4.9%) patients had a positive mpMRI and clinically significant (csPCa) diagnosis during follow-up, respectively. Among 68 men who received a Fu-Bx, the 2- and 3-years csPCa diagnosis-free survival in men with negative vs. positive Fu-mpMRI was 97% vs. 65% and 92% vs. 65%, respectively. At univariate Cox-regression analysis the presence of a positive Fu-mpMRI resulted to be significantly associated with the presence of csPCa at Fu-Bx (HR: 5.8, 95% CI: 1.3-26.6, P = 0.008). The 2- and 3-years csPCa diagnosis-free survival in men with PSAd <0.15 vs. ≥0.15 was 89% vs. 77%, and 86% vs. 66%, respectively (HR: 2.6, 95% CI: 0.75-8.87, P = 0.13). The combination of negative Fu-mpMRI and PSAd<0.15 furtherly reduced the probability of csPCa diagnosis at Fu-Bx at only 6% at 3years (HR: 9.9, 95% CI: 1.9-38.6, P < 0.001) in this subgroup of patients.

CONCLUSIONS

After a negative TBx for a positive mpMRI, more than half of Fu-mpMRI were negative. A persistent positive mpMRI was associated with a significant risk of csPCa. The risk of csPCa diagnosis in men with negative mpMRI performed after negative TBx and low PSAd was negligible.

Multiparametric magnetic resonance imaging of the prostate underestimates tumour volume of small visible lesions

OBJECTIVE

To assess the relationship between the volume of the index lesion (IL) measured at multiparametric magnetic resonance imaging (mpMRI; MRIvol) and at radical prostatectomy (RPvol), stratifying it according to Prostate Imaging-Reporting and Data System (PI-RADS) score.

PATIENTS AND METHODS

We identified 332 men with a positive mpMRI (single lesion with PI-RADS ≥3) who underwent systematic plus targeted biopsy and subsequent RP at two tertiary referral centres between 2013 and 2018. All mpMRIs were reviewed by experienced radiologists using PI-RADS scores. The study outcome was to assess the relationship between MRIvol (based on planimetry from MRI sequence best showing tumour) and RPvol (based on tumour involved area of each RP pathology slice). To achieve this endpoint, we performed a multivariable linear regression analysis (LRA) to predict RPvol using PI-RADS, prostate-specific antigen level, prostate volume, age, digital rectal examination, Gleason score at MRI-targeted biopsy, biopsy history and time from mpMRI to RP as covariates. Non-parametric locally estimated scatterplot smoothing (LOESS) function was used to graphically explore the relationship between MRIvol and RPvol, stratifying for PI-RADS score.

RESULTS

Overall, 24%, 49% and 27% of men had visible PI-RADS 3, 4 and 5 lesions at mpMRI. The median (interquartile range [IQR]) MRIvol and RPvol were 0.67 (0.29-1.76) mL and 1.39 (0.58-4.23) mL. At LRA, MRIvol was significantly correlated with a RPvol underestimation (slope: 2.4, 95% confidence interval [CI] 0.1-46.3). The non-parametric LOESS analysis showed a non-linear relationship between MRIvol and RPvol. Significant underestimation was reported across all volumes with the highest differences between MRIvol and RPvol in the low volume range (<2 mL), where RPvol almost doubled MRIvol. A similar effect was observed across all PI-RADS scores subgroups.

CONCLUSIONS

In the present study, mpMRI significantly underestimated the exact volume of the IL, especially for small visible lesions, regardless of PI-RADS score. This should be considered when planning tailored focal therapy approaches often delivered to men with smaller prostatic lesions.

Age and gleason score upgrading between prostate biopsy and radical prostatectomy: Is this still true in the multiparametric resonance imaging era?

INTRODUCTION

Several studies have invariably shown that the risk of Grade Group (GG) upgrading between biopsy and radical prostatectomy (RP) is higher in elderly men. Whether this is due to a real biological effect or to a diagnostic bias is still unknown. We hypothesized that the introduction of multiparametric magnetic resonance imaging (MRI) has improved the diagnostic accuracy of PCa detection in older men thus reducing the risk of GG upgrading at RP reported in the pre-MRI era.

MATERIALS AND METHODS

We selected 424 men who received a systematic plus targeted biopsy for a positive MRI and subsequent RP at two referral centers between 2013 and 2019. Upgrading was defined as an increase in GG at final pathology as compared to biopsy. Multivariable logistic regressions tested the risk of upgrading over increasing age according to any upgrading definition and after stratifying definitions according to GG group and biopsy type. Non-parametric functions explored the relationship between age and upgrading rate.

RESULTS

Median rate of upgrading was 17%. In multivariable models, while age was not associated with increased risk of GG upgrading (p=0.4). At non-parametric analyses, probability of upgrading slightly decreased with age, without reaching statistical significance. In subgroup analyses according to different upgrading definition and to biopsy type, age did not predict higher risk of upgrading regardless of outcome definitions (GG 1 to 2 P = 0.1; GG 2 to 3 P = 0.2; GG 3 to 4-5 P = 0.2) and in GG detected at TBx (OR 0.998, P = 0.8).

CONCLUSIONS

We showed that use of MRI has obliterated the association between older age and increased risk of upgrading mainly due to improved diagnostic approaches in this group of men. Therefore, it is likely that the effect of age and GG upgrading reported in previous studies in elderly men was due to misdiagnosis and lead-time bias in the pre-MRI era.

The role of MRI/TRUS fusion biopsy in the diagnosis of clinically significant prostate cancer

Background

The aim of this work is to evaluate the detection rate of magnetic resonance imaging/transrectal ultrasound (MRI/TRUS) fusion-guided biopsy for clinically significant prostate cancers (Cs PCas), with particular interest in biopsy-naive patients and patients in active surveillance. MRI-targeted biopsy improves cancer detection rate (DR) in patients with prior negative biopsies; the current literature focuses on biopsy naive patients. We also evaluated the pathologic concordance between biopsies and surgical specimens.

Methods

MRI/TRUS fusion-guided biopsies were performed between February 2016 and February 2019. Patients with previous negative biopsies, biopsy-naive or in active surveillance (AS) were included. Cs PCas were defined through Epstein's criteria.

Results

A total of 416 men were enrolled. The overall DRs and Cs PCa DRs were 49% and 34.3%, respectively. Cs PCas were 17.2%, 44.9% and 73.4%, respectively for PI-RADS 3, 4 or 5. Among biopsy-naive patients, 34.8% were found to have a Cs PCa, while a 43.6% tumour upgrading was achieved in men with a low risk of PCa. In patients who underwent radical prostatectomy (RP), the concordance between biopsy Gleason score (GS) (bGS) and pathological GS (pGS) was 90.8%.

Conclusion

Our study highlights the role of MRI/TRUS fusion prostate biopsy in the detection of PCa in patients with previous negative biopsies focusing on Cs PCa diagnosis. The MRI/TRUS fusion biopsy is also emerging as a diagnostic tool in biopsy-naïve patients and deserves a fundamental role in AS protocols. A greater concordance between bGS and pGS can be achieved with targeted biopsies.

Applicability of readout-segmented echoplanar diffusion weighted imaging for prostate MRI

To evaluate readout-segmented echoplanar (rsEPI) diffusion weighted imaging (DWI) for multiparametric (mp) magnetic resonance imaging (MRI) of the prostate compared to the established single-shot echoplanar imaging (ssEPI) sequence.One hundred ten consecutive patients with clinical suspicion of prostate cancer underwent mp prostate MRI using both, the ssEPI and the rsEPI DWI sequence. For an objective assessment, delineation of the prostate shape on both DWI sequences was compared to T2-weighted images by measuring organ diameters. Apparent diffusion coefficient (ADC) values, image contrast and contrast-to-noise ratio (CNR) were compared between the 2 sequences on a region-of-interest-based analysis. Diagnostic accuracy for quantitative ADC-values was calculated. Histopathology from MRI/ultrasound fusion-guided biopsy was used as reference standard. For a subjective assessment, 2 independent readers visually assessed image quality of both sequences using Likert-scales.Delineation of the prostate shape was more accurate with rsEPI compared to ssEPI. ADC values in target lesions were not significantly different but significantly higher in the surrounding normal prostatic tissue of the transition zone. CNR was comparable between ssEPI and rsEPI. Sensitivity and specificity were good for both sequences with 84/84% and 82/73% with a Youden selected cut-off of ADC = 0.971*10 mm/s for rsEPI and 1.017*10 mm/s for ssEPI. Anatomic artifacts were significantly less and SNR was lower on rsEPI compared to ssEPI in the subjective analysis.Delineation of the prostate shape was more accurate with rsEPI DWI than with ssEPI DWI with less anatomic artifacts and higher subjective SNR and image quality on rsEPI DW images. Diagnostic ability of quantitative ADC-values was not significantly different between the 2 sequences. Thus, rsEPI DWI might be more suitable for prostate MRI with regard to MRI-guided targeted biopsy and therapy planning.

Is There Still a Need for Repeated Systematic Biopsies in Patients with Previous Negative Biopsies in the Era of Magnetic Resonance Imaging-targeted Biopsies of the Prostate?

BACKGROUND

The role of targeted prostate biopsies (TBs) in patients with cancer suspicious lesions on multiparametric magnetic resonance imaging (mpMRI) following negative systematic biopsies (SBs) is undebated. However, whether they should be combined with repeated SBs remains unclear.

OBJECTIVE

To evaluate the value of repeated SBs in addition to TBs in patients with a prior negative SB and a persistent suspicion of prostate cancer (PCa).

DESIGN, SETTING, AND PARTICIPANTS

A prospective study as part of a multicenter randomized controlled trial conducted between 2014 and 2017, including 665 men with a prior negative SB and a persistent suspicion of PCa (suspicious digital rectal examination and/or prostate-specific antigen >4.0ng/ml).

INTERVENTION

All patients underwent 3T mpMRI according to Prostate Imaging Reporting and Data System (PI-RADS) v2. Patients with PI-RADS ≥3 were randomized 1:1:1 for three TB techniques: MRI-TRUS fusion TB (FUS-TB), cognitive registration fusion TB (COG-TB), or in-bore MRI TB. FUS-TB and COG-TB were combined with repeated SBs.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Clinically significant prostate cancer (csPCa) was defined as Gleason ≥3+4. Differences in detection rates of csPCa, clinically insignificant PCa (cisPCa), and overall PCa between TBs (FUS-TB and COG-TB) and repeated SBs were compared using McNemar's test.

RESULTS AND LIMITATIONS

In the 152 patients who underwent both TB and SB, PCa was detected by TB in 47% and by SB in 32% (p<0.001, 95% confidence interval [CI]: 6.0-22%). TB detected significantly more csPCa than SB (32% vs 16%; p<0.001, 95% CI: 11-25%). Clinically significant PCa was missed by TB in 1.3% (2/152). Combining SB and TB resulted in detection rate differences of 6.0% for PCa, 5.0% for cisPCa, and 1.0% for csPCa compared with TB alone.

CONCLUSIONS

In case of a persistent suspicion of PCa following a negative SB, TB detected significantly more csPCa cases than SB. The additional value of SB was limited, and only 1.3% of csPCa would have been missed when SB had been omitted.

PATIENT SUMMARY

We evaluated the role of systematic biopsies and magnetic resonance imaging (MRI)-targeted biopsies for the diagnosis of prostate cancer in patients with prior negative systematic biopsies. MRI-targeted biopsies perform better in detecting prostate cancer in these patients. The value of repeated systematic biopsies is limited.

Assessing the Clinical Value of Positive Multiparametric Magnetic Resonance Imaging in Young Men with a Suspicion of Prostate Cancer

BACKGROUND

There is a lack of evidence on the ability of magnetic resonance imaging (MRI) of the prostate to detect clinically significant prostate cancer (csPCa) in young patients.

OBJECTIVE

We hypothesised that the diagnostic performance of MRI for csPCa varies according to patient's age. To address this, we assessed the variation in the csPCa detection rate of MRI targeted biopsy (MRI-TBx) versus systematic random biopsy (SBx) across different patient ages.

DESIGN, SETTING, AND PARTICIPANTS

We retrospectively identified 930 patients who underwent prostate MRI and subsequent biopsy at two referral centres between 2013 and 2018. The Prostate Imaging Reporting and Data System (PI-RADS) was used for MRI reporting.

INTERVENTION

A lesion with a PI-RADS score of ≥3 detected at MRI received an MRI-TBx in addition to an SBx during the same session.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The outcome of our study was the relationship between age and csPCa detection rate at MRI-TBx and SBx, respectively. Clinically significant prostate cancer (PCa) was defined as the presence of PCa with Gleason score ≥3+4. Multivariable logistic regression analyses (MVAs) predicting csPCa detection were assessed for both MRI-TBx and SBx. Covariates were age, prostate-specific antigen density, PI-RADS score, previous biopsy status, digital rectal examination, and the number of targeted and systematic cores. The hypothesis that MRI accuracy in detecting csPCa differed by age was finally tested with a nonparametric loess analysis.

RESULTS AND LIMITATIONS

The overall rate of csPCa was 54% (n=506). Overall, 325 (35%) and 461 (50%) patients had csPCa at SBx and MRI-TBx, respectively. The median numbers of SBx and MRI-TBx cores were 12 (interquartile range [IQR]: 10-13) and 5 (IQR: 4-7), respectively. At MVA, age at biopsy was an independent predictor of csPCa at MRI-TBx only (odds ratio: 1.05), after accounting for confounders. In men aged less than roughly 50yr, SBx had a higher probability of detecting csPCa relative to MRI-TBx (25% vs 16% at 40yr). Conversely, in patients aged >50yr, the probability of csPCa was higher in MRI-TBx than in SBx, reaching the highest difference for very elderly patients (48% vs 68% at 80yr). The main limitations were the retrospective design and the small number of young patients.

CONCLUSIONS

In this study, we reported the performance of MRI and MRI-TBx in detecting csPCa changes according to patients' age.

PATIENT SUMMARY

In young patients, the performance of a systematic random biopsy in detecting clinically significant prostate cancer (csPCa) is higher relative to magnetic resonance imaging targeted biopsy (MRI-TBx), reflecting the lower accuracy of MRI in younger men. Conversely, in older patients, MRI-TBx showed a clinical benefit with a higher csPCa detection rate compared with SBx, suggesting an increase of MRI accuracy with the increase of age.

There Is No Way to Avoid Systematic Prostate Biopsies in Addition to Multiparametric Magnetic Resonance Imaging Targeted Biopsies

BACKGROUND

Whether or not adding systematic biopsies (transrectal ultrasound-guided biopsy [TRUS-Bx]) to targeted cores in patients with a lesion detected at multiparametric magnetic resonance imaging (mpMRI) is still a debated topic.

OBJECTIVE

To identify patients who can avoid TRUS-Bx at the time of mpMRI targeted biopsy (MRI-TBx) relying on individual patient probability to harbour clinically significant prostate cancer (csPCa) outside the index lesion (IL).

DESIGN, SETTING, AND PARTICIPANTS

A total of 339 European and 441 North American patients underwent fusion MRI-TBx and concomitant TRUS-Bx at two tertiary care referral centres between 2013 and 2017.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The study outcome was csPCa, defined as a Gleason score at biopsy of ≥7, outside the IL. Multivariable logistic regression analyses (MVAs) were performed to develop a predictive model for the study outcome. Multivariable-derived coefficients were used to develop a novel risk calculator in each cohort. The models were evaluated using the area under the curve (AUC), calibration plot, and decision-curve analyses.

RESULTS AND LIMITATIONS

In the European cohort, csPCa detection rate was 55%. The csPCa detection rate for TRUS-Bx was 41%. At MVAs, prostate volume, previous negative biopsy, and Prostate Imaging Reporting and Data System versions 4 and 5 were independent predictors for the presence of csPCa outside the IL. The multivariable model had an AUC of 0.78. Omitting TRUS-Bx in patients with a calculated risk of <15% would have spared 16% of TRUS-Bx at the cost of missing 7% of csPCa. Similar findings were obtained when the same analyses were performed in the North American cohort. No net benefit was observed for low-threshold probabilities (<15%) of the each model relative to the standard of care (performing TRUS-Bx in addition to MRI-TBx to all patients) in both cohorts. The study is limited by its retrospective design.

CONCLUSIONS

We failed to identify those patients who might safely benefit from MRI-TBx alone. The combination of MRI-TBx and TRUS-Bx should strongly be considered the best available approach.

PATIENT SUMMARY

In the presence of positive multiparametric magnetic resonance imaging (mpMRI) of the prostate, physicians should always perform systematic sampling of the prostate in addition to mpMRI targeted biopsy.

Beyond transrectal ultrasound-guided prostate biopsies: available techniques and approaches

OBJECTIVES

Recent advances have led to the use of magnetic resonance imaging (MRI) alone or with fusion to transrectal ultrasound (TRUS) images for guiding biopsy of the prostate. Our group sought to develop consensus recommendations regarding MRI-guided prostate biopsy based on currently available literature and expert opinion.

METHODS

The published literature on the subject of MRI-guided prostate biopsy was reviewed using standard search terms and synthesized and analyzed by four different subgroups from among the authors. The literature was grouped into four categories-MRI-guided biopsy platforms, robotic MRI-TRUS fusion biopsy, template mapping biopsy and transrectal MRI-TRUS fusion biopsy. Consensus recommendations were developed using the Oxford Center for Evidence Based Medicine criteria.

RESULTS

There is limited high level evidence available on the subject of MRI-guided prostate biopsy. MRI guidance with or without TRUS fusion can lead to fewer unnecessary biopsies, help identify high-risk (Gleason ≥ 3 + 4) cancers that might have been missed on standard TRUS biopsy and identify cancers in the anterior prostate. There is no apparent significant difference between MRI biopsy platforms. Template mapping biopsy is perhaps the most accurate method of assessing volume and grade of tumor but is accompanied by higher incidence of side effects compared to TRUS biopsy.

CONCLUSIONS

Magnetic resonance imaging-guided biopsies are feasible and better than traditional ultrasound-guided biopsies for detecting high-risk prostate cancer and anterior lesions. Judicious use of MRI-guided biopsy could enhance diagnosis of clinically significant prostate cancer while limiting diagnosis of insignificant cancer.

Follow-up of negative MRI-targeted prostate biopsies: when are we missing cancer?

INTRODUCTION

Multiparametric magnetic resonance imaging (mpMRI) has improved clinicians' ability to detect clinically significant prostate cancer (csPCa). Combining or fusing these images with the real-time imaging of transrectal ultrasound (TRUS) allows urologists to better sample lesions with a targeted biopsy (Tbx) leading to the detection of greater rates of csPCa and decreased rates of low-risk PCa. In this review, we evaluate the technical aspects of the mpMRI-guided Tbx procedure to identify possible sources of error and provide clinical context to a negative Tbx.

METHODS

A literature search was conducted of possible reasons for false-negative TBx. This includes discussion on false-positive mpMRI findings, termed "PCa mimics," that may incorrectly suggest high likelihood of csPCa as well as errors during Tbx resulting in inexact image fusion or biopsy needle placement.

RESULTS

Despite the strong negative predictive value associated with Tbx, concerns of missed disease often remain, especially with MR-visible lesions. This raises questions about what to do next after a negative Tbx result. Potential sources of error can arise from each step in the targeted biopsy process ranging from "PCa mimics" or technical errors during mpMRI acquisition to failure to properly register MRI and TRUS images on a fusion biopsy platform to technical or anatomic limits on needle placement accuracy.

CONCLUSIONS

A better understanding of these potential pitfalls in the mpMRI-guided Tbx procedure will aid interpretation of a negative Tbx, identify areas for improving technical proficiency, and improve both physician understanding of negative Tbx and patient-management options.

Not All Multiparametric Magnetic Resonance Imaging-targeted Biopsies Are Equal: The Impact of the Type of Approach and Operator Expertise on the Detection of Clinically Significant Prostate Cancer

BACKGROUND

The extensive use of multiparametric magnetic resonance imaging (mpMRI) has led to an even more widespread use of different targeted biopsy techniques and approaches. The best way of performing targeted biopsies and the effect of operator expertise have still to be defined.

OBJECTIVE

To compare the rate of detection of clinically significant prostate cancer (csPCa) of different mpMRI targeted approaches and to assess the role of operator expertise in the detection of csPCa.

DESIGN, SETTING, AND PARTICIPANTS

We included 244 consecutive patients who underwent both 12-core transrectal ultrasound (TRUS) biopsy and mpMRI targeted biopsy with either a cognitive biopsy (CB) or fusion biopsy (FB) approach during the same session between 2013 and 2016 at a single tertiary referral centre.

INTERVENTION

All men underwent 1.5-T mpMRI with an endorectal coil. All biopsies were performed by three operators as their first cases of targeted biopsy. Lesions with a Prostate Imaging Recording and Data System (PI-RADS) v.2 score of ≥3 detected at mpMRI were targeted. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: csPCa was defined as disease with a Gleason score at biopsy of ≥7. Operator expertise was coded as the progressive number of targeted biopsies performed by each physician. Multivariable logistic regression analyses (MVA) were used to assess the association between the targeted biopsy technique (FB vs CB) and operator expertise for detection of csPCa. Covariates consisted of prostate-specific antigen, prostate volume, PI-RADS v.2 (3 vs >3), number of targeted cores per MRI lesion, and digital rectal examination (negative vs positive). The same analyses were performed for patients undergoing FB only after accounting for the FB approach (transrectal vs transperineal). A lowess smoothing weighted function was used to graphically assess the effect of operator expertise on the probability of detecting csPCa, after accounting for all confounders.

RESULTS AND LIMITATIONS

Overall, 157 patients (64%) underwent FB and 87 (36%) underwent CB. The overall csPCa detection rate was 58% for FB and 45% for CB (p=0.07). A significantly higher rate of csPCa detection in targeted samples was observed for FB compared to CB (57% vs 36%; p=0.002). On MVA, FB and operator expertise were significantly associated with a higher probability of csPCa detection in targeted samples (odds ratio [OR] 2.4 and 1.7, respectively; both p≤0.03). When the same analyses were repeated for patients undergoing FB, operator expertise remained an independent predictor of csPCa detection (OR 1.9; p=0.004). An increase in the probability of detecting csPCa with the number of procedures performed was observed after accounting for all confounders.

CONCLUSIONS

We demonstrated that FB had higher detection rate than CB for csPCa. Moreover, operator expertise was significantly associated with higher detection rates for csPCa.

PATIENT SUMMARY

When different targeted biopsy techniques were compared, fusion biopsy provided a higher detection rate compared to cognitive biopsy for clinically significant prostate cancer (csPCa). Moreover, we found that operator expertise was an important predictor of the detection of csPCa, regardless of the procedure used.

68Gallium-Prostate-Specific Membrane Antigen PET/Computed Tomography for Primary and Secondary Staging in Prostate Cancer

Prostate-specific membrane antigen (PSMA) PET has been recently introduced for the diagnosis of patients with metastatic prostate cancer (PCa). Until today, staging of patients with PCa relied mostly on morphologic features, such as size or shape, resulting in low detection rates in disease recurrence. PSMA PET imaging provides molecular information and, in combination with conventional imaging, offers improved sensitivity and specificity. This review discusses the benefits and limitations of PSMA imaging in the setting of primary staging and detection of recurrent disease in comparison with standard-of-care imaging techniques.

Targeted 11C-choline PET-CT/TRUS software fusion-guided prostate biopsy in men with persistently elevated PSA and negative mpMRI after previous negative biopsy

Background

We evaluated the feasibility and accuracy of 11C–choline PET-CT/TRUS fusion-guided prostate biopsy in men with persistently elevated PSA and negative mpMRI or contraindication to MRI, after previous negative biopsy. Clinical data were part of a prospective on-going observational clinical study: “Diagnostic accuracy of target mpMRI/US fusion biopsy in patients with suspected prostate cancer after initial negative biopsy”. Patients with a negative biopsy and negative mpMRI (PI-RADS v.2 < 3) or absolute contraindications to MRI and persistently elevated PSA, were included. All patients underwent 11C–choline PET with dedicated acquisition of the pelvis and PET-CT/TRUS-guided prostate biopsy by Bio-Jet™ fusion system (D&K Technologies, Germany). The primary endpoint was to assess the accuracy of 11C–choline PET-CT to determine the presence and the topographical distribution of PCa.

Results

Overall, 15 patients (median age 71 yrs. ± 8.89; tPSA 13.5 ng/ml ± 4.3) were analysed. Fourteen had a positive PET scan, which revealed 30 lesions. PCa was detected in 7/15 patients (46.7%) and four patients presented a clinically significant PCa: GS > 6. Over 58 cores, 25 (43.1%) were positive. No statistically significant difference in terms of mean and median values for SUVmax and SUVratio between benign and malignant lesions was found. PCa lesions with GS 3 + 3 (n = 3) showed a median SUVmax and SUVratio of 4.01 and 1.46, compared to 5.45 and 1.57, respectively for lesions with GS >6 (n = 4).

Conclusion

Software PET-CT/TRUS fusion-guided target biopsy could be a diagnostic alternative in patients with a suspected primary PCa and negative mpMRI, but its specificity appeared low.

[MRI/TRUS fusion-guided prostate biopsy : Value in the context of focal therapy]

BACKGROUND

Several systems for MRI/TRUS fusion-guided biopsy of the prostate are commercially available. Many studies have shown superiority of fusion systems for tumor detection and diagnostic quality compared to random biopsy. The benefit of fusion systems in focal therapy of prostate cancer (PC) is less clear.

OBJECTIVES

Critical considerations of fusion systems for planning and monitoring of focal therapy of PC were investigated.

MATERIALS AND METHODS

A systematic literature review of available fusion systems for the period 2013-5/2016 was performed. A checklist of technical details, suitability for special anatomic situations and suitability for focal therapy was established by the German working group for focal therapy (Arbeitskreis fokale und Mikrotherapie).

RESULTS

Eight fusion systems were considered (Artemis™, BioJet, BiopSee®, iSR´obot™ Mona Lisa, Hitachi HI-RVS, UroNav and Urostation®). Differences were found for biopsy mode (transrectal, perineal, both), fusion mode (elastic or rigid), navigation (image-based, electromagnetic sensor-based or mechanical sensor-based) and space requirements.

DISCUSSION

Several consensus groups recommend fusion systems for focal therapy. Useful features are "needle tracking" and compatibility between fusion system and treatment device (available for Artemis™, BiopSee® and Urostation® with Focal One®; BiopSee®, Hitachi HI-RVS with NanoKnife®; BioJet, BiopSee® with cryoablation, brachytherapy).

CONCLUSIONS

There are a few studies for treatment planning. However, studies on treatment monitoring after focal therapy are missing.

Evaluation of MRI/Ultrasound Fusion-Guided Prostate Biopsy Using Transrectal and Transperineal Approaches

Purpose

To evaluate transrectal (TR) and transperineal (TP) approaches for MRI/ultrasound (MRI/US) fusion-guided biopsy to detect prostate cancer (PCa).

Materials and Methods

154 men underwent multiparametric MRI and MRI/US fusion-guided biopsy between July 2012 and October 2016. 79/154 patients were biopsied with a TR approach and 75/154 with a TP approach. MRI was retrospectively analyzed according to PI-RADS version 2. PI-RADS scores were compared with histopathological results. Descriptive statistics, accuracy, and negative and positive predictive values were calculated. Histopathological results of first, second, and third MRI targeted biopsy cores were compared to evaluate the impact of one verus multiple targeted cores.

Results

Detection rates of PCa were 39% for TR biopsy and 75% for TP biopsy. Sensitivity/specificity for tumor detection with PI-RADS ≥ 4 were 81/69% for TR biopsy and 86/84% for TP biopsy. In 31% for TR biopsy and 19% for TP biopsy, PCa was found in the second or third MRI targeted biopsy core only.

Conclusion

MRI/US fusion-guided biopsy may be conducted with the TR as well as the TP approach with high accuracy, giving more flexibility for diagnosis and the option for focal treatment of PCa.

Standardized Reporting of Prostate MRI: Comparison of the Prostate Imaging Reporting and Data System (PI-RADS) Version 1 and Version 2

Introduction

Objective of our study was to determine the agreement between version 1 (v1) and v2 of the Prostate Imaging Reporting and Data System (PI-RADS) for evaluation of multiparametric prostate MRI (mpMRI) and to compare their diagnostic accuracy, their inter-observer agreement and practicability.

Material and Methods

mpMRI including T2-weighted imaging, diffusion-weighted imaging (DWI) and dynamic contrast-enhanced imaging (DCE) of 54 consecutive patients, who subsequently underwent MRI-guided in-bore biopsy were re-analyzed according to PI-RADS v1 and v2 by two independent readers. Diagnostic accuracy for detection of prostate cancer (PCa) was assessed using ROC-curve analysis. Agreement between PI-RADS versions and observers was calculated and the time needed for scoring was determined.

Results

MRI-guided biopsy revealed PCa in 31 patients. Diagnostic accuracy for detection of PCa was equivalent with both PI-RADS versions for reader 1 with sensitivities and specificities of 84%/91% (AUC = 0.91 95%CI[0.8–1]) for PI-RADS v1 and 100%/74% (AUC = 0.92 95% CI[0.8–1]) for PI-RADS v2. Reader 2 achieved similar diagnostic accuracy with sensitivity and specificity of 74%/91% (AUC = 0.88 95%CI[0.8–1]) for PI-RADS v1 and 81%/91% (AUC = 0.91 95%CI[0.8–1]) for PI-RADS v2. Agreement between scores determined with different PI-RADS versions was good (reader 1: κ = 0.62, reader 2: κ = 0.64). Inter-observer agreement was moderate with PI-RADS v2 (κ = 0.56) and fair with v1 (κ = 0.39). The time required for building the PI-RADS score was significantly lower with PI-RADS v2 compared to v1 (24.7±2.3 s vs. 41.9±2.6 s, p<0.001).

Conclusion

Agreement between PI-RADS versions was high and both versions revealed high diagnostic accuracy for detection of PCa. Due to better inter-observer agreement for malignant lesions and less time demand, the new PI-RADS version could be more practicable for clinical routine.

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.

Diagnostic Pathway with Multiparametric Magnetic Resonance Imaging Versus Standard Pathway: Results from a Randomized Prospective Study in Biopsy-naïve Patients with Suspected Prostate Cancer

BACKGROUND

An approach based on multiparametric magnetic resonance imaging (mpMRI) might increase the detection rate (DR) of clinically significant prostate cancer (csPCa).

OBJECTIVE

To compare an mpMRI-based pathway with the standard approach for the detection of prostate cancer (PCa) and csPCa.

DESIGN, SETTING, AND PARTICIPANTS

Between November 2014 and April 2016, 212 biopsy-naïve patients with suspected PCa (prostate specific antigen level ≤15 ng/ml and negative digital rectal examination results) were included in this randomized clinical trial. Patients were randomized into a prebiopsy mpMRI group (arm A, n=107) or a standard biopsy (SB) group (arm B, n=105).

INTERVENTION

In arm A, patients with mpMRI evidence of lesions suspected for PCa underwent mpMRI/transrectal ultrasound fusion software-guided targeted biopsy (TB) (n=81). The remaining patients in arm A (n=26) with negative mpMRI results and patients in arm B underwent 12-core SB.

OUTCOMES MEASUREMENTS AND STATISTICAL ANALYSIS

The primary end point was comparison of the DR of PCa and csPCa between the two arms of the study; the secondary end point was comparison of the DR between TB and SB.

RESULTS AND LIMITATIONS

The overall DRs were higher in arm A versus arm B for PCa (50.5% vs 29.5%, respectively; p=0.002) and csPCa (43.9% vs 18.1%, respectively; p<0.001). Concerning the biopsy approach, that is, TB in arm A, SB in arm A, and SB in arm B, the overall DRs were significantly different for PCa (60.5% vs 19.2% vs 29.5%, respectively; p<0.001) and for csPCa (56.8% vs 3.8% vs 18.1%, respectively; p<0.001). The reproducibility of the study could have been affected by the single-center nature.

CONCLUSIONS

A diagnostic pathway based on mpMRI had a higher DR than the standard pathway in both PCa and csPCa.

PATIENT SUMMARY

In this randomized trial, a pathway for the diagnosis of prostate cancer based on multiparametric magnetic resonance imaging (mpMRI) was compared with the standard pathway based on random biopsy. The mpMRI-based pathway had better performance than the standard pathway.

Accuracy and agreement of PIRADSv2 for prostate cancer mpMRI: A multireader study

PURPOSE

Multiparametric MRI (mpMRI) improves the detection of clinically significant prostate cancer, but is limited by interobserver variation. The second version of theProstate Imaging Reporting and Data System (PIRADSv2) was recently proposed as a standard for interpreting mpMRI. To assess the performance and interobserver agreement of PIRADSv2 we performed a multi-reader study with five radiologists of varying experience.

MATERIALS AND METHODS

Five radiologists (n = 2 prostate dedicated, n = 3 general body) blinded to clinicopathologic results detected and scored lesions on prostate mpMRI using PIRADSv2. The endorectal coil 3 Tesla MRI included T2W, diffusion-weighted imaging (apparent diffusion coefficient, b2000), and dynamic contrast enhancement. Thirty-four consecutive patients were included. Results were correlated with radical prostatectomy whole-mount histopathology produced with patient-specific three-dimensional molds. An index lesion was defined on pathology as the lesion with highest Gleason score or largest volume if equivalent grades. Average sensitivity and positive predictive values (PPVs) for all lesions and index lesions were determined using generalized estimating equations. Interobserver agreement was evaluated using index of specific agreement.

RESULTS

Average sensitivity was 91% for detecting index lesions and 63% for all lesions across all readers. PPV was 85% for PIRADS ≥ 3 and 90% for PIRADS ≥ 4. Specialists performed better only for PIRADS ≥ 4 with sensitivity 90% versus 79% (P = 0.01) for index lesions. Index of specific agreement among readers was 93% for the detection of index lesions, 74% for the detection of all lesions, and 85% for scoring index lesions, and 58% for scoring all lesions.

CONCLUSION

By using PIRADSv2, general body radiologists and prostate specialists can detect high-grade index prostate cancer lesions with high sensitivity and agreement.

LEVEL OF EVIDENCE

1 J. Magn. Reson. Imaging 2017;45:579-585.

Modeling Cryotherapy Ice Ball Dimensions and Isotherms in a Novel Gel-based Model to Determine Optimal Cryo-needle Configurations and Settings for Potential Use in Clinical Practice

Objective

To gain a better understanding of ice ball dimensions and temperature isotherms relevant for cell kill when using combinations of cryo-needles we set out to answer 4 questions: (1) what type of cryo-needle? (2) how many needles? (3) best spatial configuration? and (4) correct duty cycle percentage?

Methods

We conducted laboratory experiments to monitor ice ball dimensions and create multi-needle planar isotherm maps for 17G and 10G cryo-needles using a novel multi-needle thermocouple fixture within gel at body temperature. We tested configurations of 1-4 cryo-needles at duty cycles of 20%-100% with 1-2.5 cm spacing.

Results

Analysis of various combinations shows that a central core of ≤−40°C develops at a distance of ~1 cm around the cryo-needles. Temperature increases linearly from this point to the ice ball leading edge (0°C), which is a further ≈1 cm away. Thus, the −40°C isotherm is approximately 1 cm inside the leading edge of the ice ball.

The optimum distance between cryo-needles was 1.5-2 cm, at duty cycle settings of 70%-100%. At distances further apart or with lower duty cycle settings, ice balls either had a central core >−40°C or had an hourglass shape.

Conclusion

In answer to questions 1-3, tumor length, diameter, and shape will ultimately determine the number of needles and their configuration. However, we propose a conservative distance for cryo-needle placement between 1 and 1.5 cm should be adopted for clinical practice. In answer to question 4, using low duty cycle settings runs the risk of incomplete −40°C isotherm coverage of the tumor, and thus in routine practice we suggest that settings of 70%-100% are most appropriate.

Multiparametric MRI and targeted prostate biopsy: Improvements in cancer detection, localization, and risk assessment

Introduction

Multiparametric-MRI (mp-MRI) is an evolving noninvasive imaging modality that increases the accurate localization of prostate cancer at the time of MRI targeted biopsy, thereby enhancing clinical risk assessment, and improving the ability to appropriately counsel patients regarding therapy.

Material and methods

We used MEDLINE/PubMed to conduct a comprehensive search of the English medical literature. Articles were reviewed, data was extracted, analyzed, and summarized. In this review, we discuss the mp-MRI prostate exam, its role in targeted prostate biopsy, along with clinical applications and outcomes of MRI targeted biopsies.

Results

Mp-MRI, consisting of T2-weighted imaging, diffusion-weighted imaging, dynamic contrast-enhanced imaging, and possibly MR spectroscopy, has demonstrated improved specificity in prostate cancer detection as compared to conventional T2-weighted images alone. An MRI suspicion score has been developed and is depicted using an institutional Likert or, more recently, a standardized reporting scale (PI-RADS). Techniques of MRI-targeted biopsy include in-gantry MRI guided biopsy, TRUS-guided visual estimation biopsy, and software co-registered MRI-US guided biopsy (MRI-US fusion). Among men with no previous biopsy, MRI-US fusion biopsy demonstrates up to a 20% increase in detection of clinically significant cancers compared to systematic biopsy while avoiding a significant portion of low risk disease. These data suggest a potential role in reducing over-detection and, ultimately, over-treatment. Among men with previous negative biopsy, 72–87% of cancers detected by MRI targeted biopsy are clinically significant. Among men with known low risk cancer, repeat biopsy by MR-targeting improves risk stratification in selecting men appropriate for active surveillance secondarily reducing the need for repetitive biopsy during surveillance.

Conclusions

Use of mp-MRI for targeting prostate biopsies has the potential to reduce the sampling error associated with conventional biopsy by providing better disease localization and sampling. MRI-ultrasound fusion-targeted prostate biopsy may improve the identification of clinically significant prostate cancer while limiting detection of indolent disease, ultimately facilitating more accurate risk stratification. Literature supports the clinical applications of MRI-targeted biopsy in men who have never been biopsied before, those with a prior negative biopsy, and those with low risk disease considering active surveillance.

Evaluation of the 'Prostate Interdisciplinary Communication and Mapping Algorithm for Biopsy and Pathology' (PIC-MABP)

INTRODUCTION

Experience from interdisciplinary cooperation revealed the need for a prostate mapping scheme to communicate multiparametric MRI (mpMRI) findings between radiologists, urologists, and pathologists, which should be detailed, yet easy to memorize. For this purpose, the 'Prostate interdisciplinary communication and mapping algorithm for biopsy and pathology' (PIC-MABP) was developed. This study evaluated the accuracy of the PIC-MABP system.

METHODS

PIC-MABP was tested and validated in findings of 10 randomly selected patients from routine clinical practise with 18 histologically proven cancer lesions. Patients received an mpMRI of the prostate prior to prostatectomy. After surgery the prostates were prepared as whole-mount step sections. Cancer lesions, which were found suspicious on mpMRI, were assigned to the according PIC-MABP sectors by a radiologist. MpMRI slides were masked and sent to seven urologists from different centres, providing only the PIC-MABP location of each lesion. Urologists marked the accordant regions. Then mpMRI slides were unmasked, and the correctness of each mark was evaluated.

RESULTS

One hundred and seventeen of the 126 marks (93%) were correctly assigned. Detection rates differed for lesions >0.5 cc compared with lesions <0.5 cc (p < 0.005): 3/7 (43%) marks were correctly assigned in lesions <0.3 cc, 16/21 (76%) in lesions with 0.3-0.5 cc, and 98/98 (100%) in lesions >0.5 cc. Interobserver agreement was good for lesions >0.5 cc and poor for lesions <0.3 cc (Fleiss Kappa 1 vs. 0.0175).

CONCLUSION

PIC-MABP seems to be a reliable system to communicate the location of mpMRI findings >0.5 cc between different disciplines and can be a useful guidance for cognitive mpMRI/TRUS fusion biopsy.