Interactive Explainable Deep Learning Model Informs Prostate Cancer Diagnosis at MRI.

Background Clinically significant prostate cancer (PCa) diagnosis at MRI requires accurate and efficient radiologic interpretation. Although artificial intelligence may assist in this task, lack of transparency has limited clinical translation. Purpose To develop an explainable artificial intelligence (XAI) model for clinically significant PCa diagnosis at biparametric MRI using Prostate Imaging Reporting and Data System (PI-RADS) features for classification justification. Materials and Methods This retrospective study included consecutive patients with histopathologic analysis-proven prostatic lesions who underwent biparametric MRI and biopsy between January 2012 and December 2017. After image annotation by two radiologists, a deep learning model was trained to detect the index lesion; classify PCa, clinically significant PCa (Gleason score ≥ 7), and benign lesions (eg, prostatitis); and justify classifications using PI-RADS features. Lesion- and patient-based performance were assessed using fivefold cross validation and areas under the receiver operating characteristic curve. Clinical feasibility was tested in a multireader study and by using the external PROSTATEx data set. Statistical evaluation of the multireader study included Mann-Whitney U and exact Fisher-Yates test. Results Overall, 1224 men (median age, 67 years; IQR, 62-73 years) had 3260 prostatic lesions (372 lesions with Gleason score of 6; 743 lesions with Gleason score of ≥ 7; 2145 benign lesions). XAI reliably detected clinically significant PCa in internal (area under the receiver operating characteristic curve, 0.89) and external test sets (area under the receiver operating characteristic curve, 0.87) with a sensitivity of 93% (95% CI: 87, 98) and an average of one false-positive finding per patient. Accuracy of the visual and textual explanations of XAI classifications was 80% (1080 of 1352), confirmed by experts. XAI-assisted readings improved the confidence (4.1 vs 3.4 on a five-point Likert scale; P = .007) of nonexperts in assessing PI-RADS 3 lesions, reducing reading time by 58 seconds (P = .009). Conclusion The explainable AI model reliably detected and classified clinically significant prostate cancer and improved the confidence and reading time of nonexperts while providing visual and textual explanations using well-established imaging features. © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Chapiro in this issue.

Injectable autologous chondrocyte implantation in acetabular cartilage defects: 2-year minimum clinical and MRI results.

INTRODUCTION: Early results using injectable autologous chondrocyte implantation (ACI) for the treatment of full thickness acetabular cartilage defects have been promising. However, so far there is no information on radiological results after injectable ACI using spheroids. The purpose of this sturdy was to (1) investigate the quality of tissue repair on MRI and (2) investigate the correlation between the MRI results and clinical results at a minimum follow-up of 24 months after third generation ACI in full thickness acetabular cartilage defects. It was hypothesized that ACI shows good MRI results in patients with large full thickness acetabular cartilage defects 24 months after surgery. It was also hypothesized that there is a correlation between postoperative clinical and MRI morphological results at a minimum follow-up of 24 months. STUDY DESIGN: Retrospective case series. MATERIALS AND METHODS: Patients with ACI for full thickness acetabular cartilage defects > 2 cm2 were evaluated by preoperative and postoperative clinical scoring tools including the modified Harris Hip Score (mHHS), the International Hip Outcome Tool (iHOT-33), and the Subjective Hip Value (SHV) as well as a high resolution indirect arthro-MRI 24 months after surgery utilizing an identical imaging protocol for all patients. The magnetic resonance observation of cartilage repair tissue (MOCART) scoring system was used to classify the repair tissue on MRI. Demographic patient data was evaluated for influencing factors for pre- and postoperative clinical as well as radiological results. RESULTS: Thirty six consecutive patients (5 women/31 men, average age 32.9 years) had undergone two stage ACI procedure. The average size of the cartilage defect was 5.0 (2-6) cm2. The average follow-up was 29.9 (24-42) months. Four patients were not available for the final follow-up (follow-up rate 89%). The postoperative average MOCART score was 82.2 (± 14.2). MOCART score showed medium correlation of the item defect fill and the postoperative mHHS (r = 0.384, p = 0.043). There was no correlation of the other items or the total score with postoperative results. The patients showed significant improvement in the outcome measurements between preoperative and postoperative in the mHHS, the iHOT-33, and the SHV. CONCLUSIONS: Despite the large acetabular cartilage defects included in this study, ACI showed good MRI results with complete defect fill in 87.5% after a minimum 24-month follow-up. Statistically significant correlation of MRI and clinical results could only be seen with the item defect fill. Further research with longer follow-up is needed to evaluate the long-term results of ACI in acetabular cartilage defects.

Comparison of Choi, RECIST and Somatostatin Receptor PET/CT Based Criteria for the Evaluation of Response and Response Prediction to PRRT.

Aim: The most suitable method for assessment of response to peptide receptor radionuclide therapy (PRRT) of neuroendocrine tumors (NET) is still under debate. In this study we aimed to compare size (RECIST 1.1), density (Choi), Standardized Uptake Value (SUV) and a newly defined ZP combined parameter derived from Somatostatin Receptor (SSR) PET/CT for prediction of both response to PRRT and overall survival (OS). Material and Methods: Thirty-four NET patients with progressive disease (F:M 23:11; mean age 61.2 y; SD ± 12) treated with PRRT using either Lu-177 DOTATOC or Lu-177 DOTATATE and imaged with Ga-68 SSR PET/CT approximately 10-12 weeks prior to and after each treatment cycle were retrospectively analyzed. Median duration of follow-up after the first cycle was 63.9 months (range 6.2-86.2). A total of 77 lesions (2-8 per patient) were analyzed. Response assessment was performed according to RECIST 1.1, Choi and modified EORTC (MORE) criteria. In addition, a new parameter named ZP, the product of Hounsfield unit (HU) and SUVmean (Standard Uptake Value) of a tumor lesion, was tested. Further, SUV values (max and mean) of the tumor were normalized to SUV of normal liver parenchyma. Tumor response was defined as CR, PR, or SD. Gold standard for comparison of baseline parameters for prediction of response of individual target lesions to PRRT was change in size of lesions according to RECIST 1.1. For prediction of overall survival, the response after the first and second PRRT were tested. Results: Based on RECIST 1.1, Choi, MORE, and ZP, 85.3%, 64.7%, 61.8%, and 70.6% achieved a response whereas 14.7%, 35.3%, 38.2%, and 29.4% demonstrated PD (progressive disease), respectively. Baseline ZP and ZPnormalized were found to be the only parameters predictive of lesion progression after three PRRT cycles (AUC ZP 0.753; 95% CI 0.6-0.9, p 0.037; AUC ZPnormalized 0.766; 95% CI 0.6-0.9; p 0.029). Based on a cut-off-value of 1201, ZP achieved a sensitivity of 86% and a specificity of 67%, while ZPnormalized reached a sensitivity of 86% and a specificity of 76% at a cut-off-value of 198. Median OS in the total cohort was not reached. In univariate analysis amongst all parameters, only patients having progressive disease according to MORE after the second cycle of PRRT were found to have significantly shorter overall survival (median OS in objective responders not reached, in PD 29.2 months; p 0.015). Patients progressive after two cycles of PRRT according to ZP had shorter OS compared to those responding (median OS for responders not reached, for PD 47.2 months, p 0.066). Conclusions: In this explorative study, we showed that Choi, RECIST 1.1, and SUVmax-based response evaluation varied significantly from each other. Only patients showing progressive disease after two PRRT cycles according to MORE criteria had a worse prognosis while baseline ZP and ZPnormalized performed best in predicting lesion progression after three cycles of PRRT.

Tertiary survey ultrasound has no diagnostic benefit in trauma patients without abdominal injuries on standardised initial whole-body computed tomography.

PURPOSE: The aim of our study was to evaluate the impact of a routine tertiary survey ultrasound (US) on patient management in major trauma patients without trauma-related abdominal findings on standardised initial whole-body CT (WBCT). METHODS: In this retrospective study, all WBCT scans acquired in major trauma patients between 07/2017 and 12/2019 at a university hospital and level I trauma centre were screened. 1,024 patients were included in the final analysis. Results of tertiary survey US and patient information (demographic data, trauma mechanism, imaging findings, clinical course, medical history, and anticoagulative medication) were collected and analysed. RESULTS: Routine tertiary survey US revealed new abdominal findings in six out of 1,024 patients (0.6%). None of the patients had to undergo surgery or minimally invasive intervention, nor did any of the patients die as a result of abdominal injuries. Additional abdominal imaging after tertiary survey US was ordered in 39 patients (38 US, 1 US + CT). None of these patients required further treatment for abdominal injuries. CONCLUSIONS: Routine tertiary survey US after inconspicuous standardised initial WBCT did not change clinical outcome for abdominal trauma patients.

International Multi-Site Initiative to Develop an MRI-Inclusive Nomogram for Side-Specific Prediction of Extraprostatic Extension of Prostate Cancer.

BACKGROUND: To develop an international, multi-site nomogram for side-specific prediction of extraprostatic extension (EPE) of prostate cancer based on clinical, biopsy, and magnetic resonance imaging- (MRI) derived data. METHODS: Ten institutions from the USA and Europe contributed clinical and side-specific biopsy and MRI variables of consecutive patients who underwent prostatectomy. A logistic regression model was used to develop a nomogram for predicting side-specific EPE on prostatectomy specimens. The performance of the statistical model was evaluated by bootstrap resampling and cross validation and compared with the performance of benchmark models that do not incorporate MRI findings. RESULTS: Data from 840 patients were analyzed; pathologic EPE was found in 320/840 (31.8%). The nomogram model included patient age, prostate-specific antigen density, side-specific biopsy data (i.e., Gleason grade group, percent positive cores, tumor extent), and side-specific MRI features (i.e., presence of a PI-RADSv2 4 or 5 lesion, level of suspicion for EPE, length of capsular contact). The area under the receiver operating characteristic curve of the new, MRI-inclusive model (0.828, 95% confidence limits: 0.805, 0.852) was significantly higher than that of any of the benchmark models (p < 0.001 for all). CONCLUSIONS: In an international, multi-site study, we developed an MRI-inclusive nomogram for the side-specific prediction of EPE of prostate cancer that demonstrated significantly greater accuracy than clinical benchmark models.

Shortened Tracer Uptake Time in GA-68-DOTATOC-PET of Meningiomas Does Not Impair Diagnostic Accuracy and PET Volume Definition.

Ga-68-DOTATOC-PET/MRI can affect the planning target volume (PTV) definition of meningiomas before radiosurgery. A shorter tracer uptake time before image acquisition could allow the examination of more patients. The aim of this study was to investigate if shortening uptake time is possible without compromising diagnostic accuracy and PET volume. Fifteen patients (f = 12; mean age 52 years (34-80 years)) with meningiomas were prospectively examined with dynamic [68Ga]Ga-68-labeled [DOTA0-Phe1-Tyr3] octreotide (Ga-68-DOTATOC)-PET/MRI over 70 min before radiosurgery planning. Meningiomas were delineated manually in the PET dataset. PET volumes at each time point were compared to the reference standard 60 min post tracer injection (p.i.) using the Friedman test followed by a Wilcoxon signed-rank test and Bonferroni correction. In all patients, the earliest time point with 100% lesion detection compared to 60 min p.i. was identified. PET volumes did not change significantly from 15 min p.i. (p = 1.0) compared to 60 min p.i. The earliest time point with 100% lesion detection in all patients was 10 min p.i. In patients with meningiomas undergoing Ga-68-DOTATOC-PET, the tracer uptake time can safely be reduced to 15 min p.i. with comparable PET volume and 100% lesion detection compared to 60 min p.i.

Comparison of Structural Subscapularis Integrity After Latarjet Procedure Versus Iliac Crest Bone Graft Transfer.

BACKGROUND: Although clinical outcome scores are comparable after coracoid transfer procedure (Latarjet) and iliac crest bone graft transfer (ICBGT) for anterior shoulder instability with glenoid bone loss, a significant decrease in internal rotation capacity has been reported for the Latarjet procedure. HYPOTHESIS: The subscapularis (SSC) musculotendinous integrity will be less compromised by ICBGT than by the Latarjet procedure. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: We retrospectively analyzed pre- and postoperative computed tomography (CT) scans at short-term follow-up of 52 patients (26 Latarjet, 26 ICBGT) previously assessed in a prospective randomized controlled trial. Measurements included the preoperative glenoid defect area and graft area protruding the glenoid rim at follow-up and tendon thickness assessed through SSC and infraspinatus (ISP) ratios. Fatty muscle infiltration was graded according to Goutallier, quantified with muscle attenuation in Hounsfield units, and additionally calculated as percentages. We measured 3 angles to describe rerouting of the SSC musculotendinous unit around the bone grafts. RESULTS: SSC fatty muscle infiltration was 2.0% ± 2.2% in the Latarjet group versus 2.4% ± 2.2% in ICBGT (P = .546) preoperatively and showed significantly higher values in the Latarjet group at follow-up (5.3% ± 4.5% vs 2.3% ± 1.7%; P = .001). In total, 4 patients (15.4%) in the Latarjet group showed a progression from grade 0 to grade 1 at follow-up, whereas no changes in the ICBGT group were noted. The measured rerouting angle of the SSC muscle was significantly increased in the Latarjet group (11.8° ± 2.1°) compared with ICBGT (7.5° ± 1.3°; P < .001) at follow-up, with a significant positive correlation between this angle and fatty muscle infiltration (R = 0.447; P = .008). Ratios of SSC/ISP tendon thickness were 1.03 ± 0.3 in the Latarjet group versus 0.97 ± 0.3 (P = .383) in ICBGT preoperatively and showed significantly lower ratios in the Latarjet group (0.7 ± 0.3 vs 1.0 ± 0.2; P < .001) at follow-up. CONCLUSION: Although clinical outcome scores after anterior shoulder stabilization with a Latarjet procedure and ICBGT are comparable, this study shows that the described decline in internal rotation capacity after Latarjet procedure has a radiographic structural correlate in terms of marked thinning and rerouting of the SSC tendon as well as slight fatty degeneration of the muscle.

Optimizing size thresholds for detection of clinically significant prostate cancer on MRI: Peripheral zone cancers are smaller and more predictable than transition zone tumors.

PURPOSE: To evaluate if size-based cut-offs based on MR imaging can successfully assess clinically significant prostate cancer (csPCA). The goal was to improve the currently applied size-based differentiation criterion in PI-RADS. METHODS AND MATERIALS: MRIs of 293 patients who had undergone 3 T MR imaging with subsequent confirmation of prostate cancer on systematic and targeted MRI/TRUS-fusion biopsy were re-read by three radiologists. All identifiable tumors were measured on T2WI for lesions originating in the transition zone (TZ) and on DWI for lesions from the peripheral zone (PZ) and tabulated against their Gleason grade. RESULTS: 309 lesions were analyzed, 213 (68.9 %) in the PZ and 96 (31.1 %) in the TZ. ROC-Analysis showed a stronger correlation between lesion size and clinically significant (defined as Gleason Grade Group ≥ 2) prostate cancer (PCa) for the PZ (AUC = 0.73) compared to the TZ (AUC = 0.63). The calculated Youden index resulted in size cut-offs of 14 mm for PZ and 21 mm for TZ tumors. CONCLUSION: Size cut-offs can be used to stratify prostate cancer with different optimal size thresholds in the peripheral zone and transition zone. There was a clearer separation of clinically significant tumors in peripheral zone cancers compared to transition zone cancers. Future iterations of PI-RADS could therefore take different size-based cut-offs for peripheral zone and transition zone cancers into account.

The influence of posture and scapulothoracic orientation on the choice of humeral component retrotorsion in reverse total shoulder arthroplasty.

BACKGROUND: The literature suggests implantation of the humeral component in reverse total shoulder arthroplasty (RTSA) in 0°-40° of retrotorsion without further specification. We hypothesized that optimal humeral component retrotorsion to avoid notching and gain balanced rotational capacity would depend on scapular position and posture. METHODS: We investigated 200 shoulders in 100 patients with available whole-body computed tomography scans and created 3-dimensional models. Implantation of a humeral component in 20° of retrotorsion was simulated, and a correction angle (CA) to yield perfect opposition to the glenosphere was calculated. Patient-specific variables such as age, sex, posture, and scapular orientation parameters were correlated with this CA. RESULTS: Scapular orientation showed large interindividual differences. A highly significant correlation was seen between the CA and scapular internal rotation (R = 0.71, P < .001) and protraction (R = 0.39, P < .001). When the CA was adjusted for glenoid retroversion, the correlation coefficient of scapular internal rotation increased even further (R = 0.91, P < .001). Scapular internal rotation itself showed a correlation with thoracic kyphosis (R = 0.27, P < .001), protraction (R = 0.57, P < .001), tilt (R = 0.29, P < .001), and scapular translation (R = -0.23, P < .001). CONCLUSION: Scapular orientation and posture should be integrated into the determination process of humeral component retrotorsion in RTSA. In theory, implantation of the humeral component with increased retrotorsion leads to improved neutral opposition of the RTSA components in patients with extensive internal rotation of the scapula. On the basis of varying scapular internal rotation, we propose the distinction of 3 different posture types (A-C) for enhanced appraisal of scapulothoracic orientation.

Author Correction: Evaluation of T1 relaxation time in prostate cancer and benign prostate tissue using a Modified Look-Locker inversion recovery sequence.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Validation of the PI-RADS language: predictive values of PI-RADS lexicon descriptors for detection of prostate cancer.

OBJECTIVES: To assess the discriminatory power of lexicon terms used in PI-RADS version 2 to describe MRI features of prostate lesions. METHODS: Four hundred fifty-four patients were included in this retrospective, institutional review board-approved study. Patients received multiparametric (mp) MRI and subsequent prostate biopsy including MRI/transrectal ultrasound fusion biopsy and 10-core systematic biopsy. PI-RADS lexicon terms describing lesion characteristics on mpMRI were assigned to lesions by experienced readers. Positive and negative predictive values (PPV, NPV) of each lexicon term were assessed using biopsy results as a reference standard. RESULTS: From a total of 501 lesions, clinically significant prostate cancer (csPCa) was present in 175 lesions (34.9%). Terms related to findings of restricted diffusion showed PPVs of up to 52.0%/43.9% and NPV of up to 91.8%/89.7% (peripheral zone or PZ/transition zone or TZ). T2-weighted imaging (T2W)-related terms showed a wide range of predictive values. For PZ lesions, high PPVs were found for "markedly hypointense," "lenticular," "lobulated," and "spiculated" (PPVs between 67.2 and 56.7%). For TZ lesions, high PPVs were found for "water-drop-shaped" and "erased charcoal sign" (78.6% and 61.0%). The terms "encapsulated," "organized chaos," and "linear" showed to be good predictors for benignity with distinctively low PPVs between 5.4 and 6.9%. Most T2WI-related terms showed improved predictive values for TZ lesions when combined with DWI-related findings. CONCLUSIONS: Lexicon terms with high discriminatory power were identified (e.g., "markedly hypointense," "water-drop-shaped," "organized chaos"). DWI-related terms can be useful for excluding TZ cancer. Combining T2WI- with DWI findings in TZ lesions markedly improved predictive values. KEY POINTS: • Lexicon terms describing morphological and functional features of prostate lesions on MRI show a wide range of predictive values for prostate cancer. • Some T2-related terms have favorable PPVs, e.g., "water-drop-shaped" and "organized chaos" while others show less distinctive predictive values. DWI-related terms have noticeable negative predictive values in TZ lesions making DWI feature a useful tool for exclusion of TZ cancer. • Combining DWI- and T2-related lexicon terms for assessment of TZ lesions markedly improves PPVs. Most T2-related lexicon terms showed a significant decrease in PPV when combined with negative findings for "DW hyperintensity."

Evaluation of T1 relaxation time in prostate cancer and benign prostate tissue using a Modified Look-Locker inversion recovery sequence.

Purpose of this study was to evaluate the diagnostic performance of T1 relaxation time (T1) for differentiating prostate cancer (PCa) from benign tissue as well as high- from low-grade PCa. Twenty-three patients with suspicion for PCa were included in this prospective study. 3 T MRI including a Modified Look-Locker inversion recovery sequence was acquired. Subsequent targeted and systematic prostate biopsy served as a reference standard. T1 and apparent diffusion coefficient (ADC) value in PCa and reference regions without malignancy as well as high- and low-grade PCa were compared using the Mann-Whitney U test. The performance of T1, ADC value, and a combination of both to differentiate PCa and reference regions was assessed by receiver operating characteristic (ROC) analysis. T1 and ADC value were lower in PCa compared to reference regions in the peripheral and transition zone (p < 0.001). ROC analysis revealed high AUCs for T1 (0.92; 95%-CI, 0.87-0.98) and ADC value (0.97; 95%-CI, 0.94 to 1.0) when differentiating PCa and reference regions. A combination of T1 and ADC value yielded an even higher AUC. The difference was statistically significant comparing it to the AUC for ADC value alone (p = 0.02). No significant differences were found between high- and low-grade PCa for T1 (p = 0.31) and ADC value (p = 0.8). T1 relaxation time differs significantly between PCa and benign prostate tissue with lower T1 in PCa. It could represent an imaging biomarker for PCa.

Combined tumor plus nontumor interim FDG-PET parameters are prognostic for response to chemoradiation in squamous cell esophageal cancer.

We have investigated the prognostic value of two novel interim 18 F-fluorodeoxyglucose positron emission tomography (FDG-PET) parameters in patients undergoing chemoradiation (CRT) for esophageal squamous cell carcinoma (ESCC): one tumor parameter (maximal standardized uptake ratio rSUR) and one normal tissue parameter (change of FDG uptake within irradiated nontumor-affected esophagus ∆SUVNTO ). PET data of 134 European and Chinese patients were analyzed. Parameter establishment was based on 36 patients undergoing preoperative CRT plus surgery, validation was performed in 98 patients receiving definitive CRT. Patients received PET imaging prior and during fourth week of CRT. Clinical parameters, baseline PET parameters, and interim PET parameters (rSUR and ∆SUVNTO ) were analyzed and compared to event-free survival (EFS), overall survival (OS), loco-regional control (LRC) and freedom from distant metastases (FFDM). Combining rSUR and ∆SUVNTO revealed a strong prognostic impact on EFS, OS, LRC and FFDM in patients undergoing preoperative CRT. In the definitive CRT cohort, univariate analysis with respect to EFS revealed several staging plus both previously established interim PET parameters as significant prognostic factors. Multivariate analyses revealed only rSUR and ∆SUVNTO as independent prognostic factors (p = 0.003, p = 0.008). Combination of these parameters with the cutoff established in preoperative CRT revealed excellent discrimination of patients with a long or short EFS (73% vs. 17% at 2 years, respectively) and significantly discriminated all other endpoints (OS, p < 0.001; LRC, p < 0.001; FFDM, p = 0.02), even in subgroups. Combined use of interim FDG-PET derived parameters ∆SUVNTO and rSUR seems to have predictive potential, allowing to select responders for definitive CRT and omission of surgery.

Additive Value of Transrectal Systematic Ventral Biopsies in Combination with Magnet Resonance Imaging/Ultrasound Fusion-Guided Biopsy in Patients with 3 or More Negative Prostate Biopsies.

INTRODUCTION: Patients with consistent suspicion for prostate cancer (PCa) and multiple negative prebiopsies prior to multiparametric magnetic resonance imaging (mpMRI) are still frequently evaluated for an image-guided biopsy and are reported with heterogeneous detection rates. The inclusion of a systematic biopsy (SB) is also still recommended with predominant sampling within the posterior/peripheral zone of the prostate. The aim of this study was (I) to evaluate PCa detection rates using a modified 10 core SB template including anterior biopsies in combination with mpMRI/ultrasound fusion-guided targeted biopsy (TB) in patients with 3 or more negative prebiopsies and (II) to compare mpMRI index lesion localization with histologically confirmed locali-zation from associated prostatectomy samples. METHODS: Overall 1,337 consecutive patients underwent sensor-based registration TB of the prostate and a subsequent 10-core SB between January 2012 and December 2015 at our institution. For this study, 101 patients with ≥3 negative prebiopsies and prostate imaging - reporting data system lesions ≥3 were pooled prospectively and underwent TB and a modified SB including 2 ventral (anterior) biopsies. Detection rates were estimated for the modified SB, TB, and its combination. A subgroup analysis of 35 patients undergoing prostatectomy was performed by a head-to-head comparison of mpMRI index lesion and histologically confirmed PCa index lesion localization. RESULTS: The overall detection rate for PCa was 54.5%. The combination of TB and SB detected 14 (25.4%) more cases missed by TB alone (p < 0.001) and 7 (12.7%) more cases missed by SB alone (p = 0.016), respectively. A postoperative Gleason upgrade was seen in 12/35 (34.3%) cases within the TB group and in 14/35 (40.0%) in the SB group, respectively. The subgroup analysis showed a predominant location of PCa index lesions anteriorly at the level of the midgland. The MRI detection rate of the anteriorly located index lesions was 70.4% (15/21 cases) with a clinically significant Gleason score (≥3 + 4 = 7a [International Society of Urological Pathology grade 2]) in 80.9%. Interestingly a modified SB template detected 90.5% (19/21) of the anteriorly located index lesions. CONCLUSION: Our data suggest that in patients with multiple prebiopsies PCa seems to be predominantly located anteriorly. We suggest the general integration of anterior biopsies despite TB in repeat biopsy patients.

Image-guided Irreversible Electroporation of Localized Prostate Cancer: Functional and Oncologic Outcomes.

Background Irreversible electroporation (IRE) is a nonthermal ablative method based on the formation of nanoscale defects in cell membranes leading to cell death. Clinical experience with the technique for treatment of prostate cancer remains limited. Purpose To evaluate urogenital toxicity and oncologic outcome of MRI-transrectal US fusion-guided IRE of localized prostate cancer. Materials and Methods In this prospective study, men with biopsy-proven, treatment-naive, low- to intermediate-risk prostate cancer (prostate-specific antigen [PSA], ≤15 ng/mL; Gleason score, ≤3 + 4; clinical stage, ≤T2c; lesion size at multiparametric MRI, ≤20 mm) underwent focal MRI/transrectal US fusion-guided IRE between July 2014 and July 2017. Primary end point was the urogenital toxicity profile of focal IRE by using participant-reported questionnaires. Secondary end points were biochemical, histologic, and imaging measures of oncologic control. Analyses were performed by using nonparametric and χ2 test statistics. Results Thirty men were included (median age, 65.5 years); mean PSA level was 8.65 ng/mL and mean tumor size was 13.5 mm. One grade III adverse event (urethral stricture) was recorded. The proportion of men with erection sufficient for penetration was 83.3% (25 of 30) at baseline and 79.3% (23 of 29; P > .99) at 12 months. Leak-free and pad-free continence rate was 90% (27 of 30) at baseline and 86.2% (25 of 29; P > .99) at 12 months. Urogenital function remained stable at 12 months according to changes in the modified International Consultation on Incontinence Questionnaire Male Lower Urinary Tract Symptoms, or ICIQ-MLUTS, and the International Index of Erectile Function, or IIEF-5, questionnaires (P = .58 and P = .07, respectively). PSA level decreased from a baseline median value of 8.65 ng/mL (interquartile range, 5-11.4 ng/mL) to 2.35 ng/mL (interquartile range, 1-3.4 ng/mL) at 12 months (P < .001). At 6 months, 28 of 30 participants underwent posttreatment biopsy. The rate of in-field treatment failure was 17.9% (five of 28) as determined with multiparametric prostate MRI and targeted biopsies at 6 months. Conclusion After a median follow-up of 20 months, focal irreversible electroporation of localized prostate cancer was associated with low urogenital toxicity and promising oncologic outcomes. © RSNA, 2019 Online supplemental material is available for this article.

Impact of 68Ga-DOTATOC PET/MRI on robotic radiosurgery treatment planning in meningioma patients: first experiences in a single institution.

OBJECTIVEFor stereotactic radiosurgery (SRS) planning, precise contouring of tumor boundaries and organs at risk is of utmost importance. Correct interpretation of standard neuroimaging (i.e., CT and MRI) can be challenging after previous surgeries or in cases of skull base lesions with complex shapes. The aim of this study was to evaluate the impact of 68Ga-DOTATOC PET/MRI on treatment planning for image-guided SRS by CyberKnife.METHODSThe authors retrospectively identified 11 meningioma treatments in 10 patients who received a 68Ga-DOTATOC PET/MRI prior to SRS. The planning target volume (PTV) used for the patients' treatment was defined as the reference standard. This was contoured by a treating radiosurgeon (RS0) using fused planning CT and PET/MRI data sets. The same tumors were then contoured by another experienced radiosurgeon (RS1) and by a less-experienced radiosurgeon (RS2), both blinded to PET data sets. A comparison of target volumes with focus on volume-based metrics and distance to critical structures was performed. RS1 and RS2 also filled in a questionnaire analyzing the confidence level and the subjective need for the implementation of PET data sets for contouring.RESULTSAnalysis showed a subjective personal preference for PET/MRI in all cases for both radiosurgeons, particularly in proximity to critical structures. The analysis of the planning volumes per physician showed significantly smaller RS2-PTV in comparison to RS1-PTV and to RS0-PTV, whereas the median volumes were comparable between RS1-PTV and RS2-PTV (median: RS0: 4.3 cm3 [IQR 3.4-6.5 cm3] and RS1: 4.5 cm3 [IQR 2.7-6 cm3] vs RS2: 2.6 cm3 [IQR 2-5 cm3]; p = 0.003). This was also reflected in the best spatial congruency between the 2 experienced physicians (RS0 and RS1). The percentage of the left-out volume contoured by RS1 and RS2 compared to RS0 with PET/MRI demonstrated a relevant left-out-volume portion in both cases with greater extent for the less-experienced radiosurgeon (RS2) (RS1: 19.1% [IQR 8.5%-22%] vs RS2: 40.2% [IQR 34.2%-53%]). No significant differences were detected regarding investigated critical structures.CONCLUSIONSThis study demonstrated a relevant impact of PET/MRI on target volume delineation of meningiomas. The extent was highly dependent on the experience of the treating physician. This preliminary study supports the relevance of 68Ga-DOTATOC PET/MRI as a tool for radiosurgical treatment planning of meningiomas.

Ga-68-PSMA PET/CT in treatment-naïve patients with prostate cancer: Which clinical parameters and risk stratification systems best predict PSMA-positive metastases?

PURPOSE: To evaluate the accuracy of clinical parameters and established pre-treatment risk stratification systems for prostate cancer (PCa) in predicting PSMA-positive metastases in men undergoing Ga-68-PSMA PET/CT as initial staging examination. MATERIALS AND METHODS: A retrospective analysis in 108 consecutive treatment-naïve patients with biopsy-proven PCa undergoing Ga-68-PSMA PET/CT (median age, 72 years [range, 49-82 years]) was performed. Prediction of PSMA-positive metastases by serum PSA, clinical T stage (cT), ISUP group, percentage of positive biopsy cores, and derived risk scores (D'Amico risk classification system, Roach [RF], Yale formula [YF], and Briganti nomogram [BN]) was examined with ROC analysis. RESULTS: Any PSMA-positive metastases were found in 36 of 108 patients, including LN metastases in 28 patients, extrapelvic LN metastases in 15 patients, and organ metastases in 19 patients (bone, 19; lung, 1). AUCs for PSA, cT, ISUP, and percentage of positive biopsy cores regarding PSMA-positive metastases did not differ significantly (range, 0.6-0.8; each P > 0.05). D'Amico (AUC, 0.61-0.64) was inferior to RF (0.76-0.83), YF (0.81-0.86), and BN (0.73 to 0.88; each P < 0.05). Among the 89 high-risk patients (D'Amico), decision for or against PET imaging based on RF (cut-off, >18.0), YF (>10.8), or BN (>8.0) would have prevented PSMA PET/CT in 4 (5%), 15 (17%), or 18 patients (20%), respectively, while preserving a sensitivity ≥95% for PSMA-positive metastases. CONCLUSIONS: Clinical parameters and established risk stratification systems for PCa can predict Ga-68-PSMA PET-positive metastases in treatment-naïve patients. Especially YF and BN may improve identification of patients with the highest probability of metastatic disease detected by Ga-68-PSMA PET/CT.

PSMA-PET based radiotherapy: a review of initial experiences, survey on current practice and future perspectives.

68Gallium prostate specific membrane antigen (PSMA) ligand positron emission tomography (PET) is an increasingly used imaging modality in prostate cancer, especially in cases of tumor recurrence after curative intended therapy. Owed to the novelty of the PSMA-targeting tracers, clinical evidence on the value of PSMA-PET is moderate but rapidly increasing. State of the art imaging is pivotal for radiotherapy treatment planning as it may affect dose prescription, target delineation and use of concomitant therapy.This review summarizes the evidence on PSMA-PET imaging from a radiation oncologist's point of view. Additionally a short survey containing twelve examples of patients and 6 additional questions was performed in seven mayor academic centers with experience in PSMA ligand imaging and the findings are reported here.

A direct comparison of contrast-enhanced ultrasound and dynamic contrast-enhanced magnetic resonance imaging for prostate cancer detection and prediction of aggressiveness.

INTRODUCTION: Dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) and contrast-enhanced ultrasound (CEUS) analyse tissue vascularization. We evaluated if CEUS can provide comparable information as DCE-MRI for the detection of prostate cancer (PCa) and prediction of its aggressiveness. MATERIAL AND METHODS: A post-hoc evaluation of 92 patients was performed. In each patient CEUS and DCE-MRI parameters of the most suspicious lesion identified on MRI were analysed. The predictive values for discrimination between benign lesions, low-/intermediate- and high-grade PCa were evaluated. Results of targeted biopsy served as reference standard (benign lesions, n=51; low- and intermediate-grade PCa [Gleason grade group 1 and 2], n=22; high-grade PCa [≥ Gleason grade group 3], n=19). RESULTS: In peripheral zone lesions of all tested CEUS parameters only time to peak (TTPCEUS) showed significant differences between benign lesions and PCa (AUC 0.65). Of all tested DCE-MRI parameters, rate constant (Kep) was the best discriminator of high-grade PCa in the whole prostate (AUC 0.83) and in peripheral zone lesions (AUC 0.89). CONCLUSION: DCE-MRI showed a superior performance for detection of PCa and prediction of its aggressiveness. CEUS and DCE-MRI performed better in peripheral zone lesions than in transition zone lesions. KEY POINTS: • DCE-MRI gathers information about vascularization and capillary permeability characteristics of tissues. • DCE-MRI can detect PCa and predict its aggressiveness. • CEUS also gathers information about vascularization of tissues. • For detection of PCa and prediction of aggressiveness DCE-MRI performed superiorly. • Both imaging techniques performed better in peripheral zone lesions.