Habitat escalated adaptive therapy (HEAT): a phase 2 trial utilizing radiomic habitat-directed and genomic-adjusted radiation dose (GARD) optimization for high-grade soft tissue sarcoma.

BACKGROUND: Soft tissue sarcomas (STS), have significant inter- and intra-tumoral heterogeneity, with poor response to standard neoadjuvant radiotherapy (RT). Achieving a favorable pathologic response (FPR ≥ 95%) from RT is associated with improved patient outcome. Genomic adjusted radiation dose (GARD), a radiation-specific metric that quantifies the expected RT treatment effect as a function of tumor dose and genomics, proposed that STS is significantly underdosed. STS have significant radiomic heterogeneity, where radiomic habitats can delineate regions of intra-tumoral hypoxia and radioresistance. We designed a novel clinical trial, Habitat Escalated Adaptive Therapy (HEAT), utilizing radiomic habitats to identify areas of radioresistance within the tumor and targeting them with GARD-optimized doses, to improve FPR in high-grade STS. METHODS: Phase 2 non-randomized single-arm clinical trial includes non-metastatic, resectable high-grade STS patients. Pre-treatment multiparametric MRIs (mpMRI) delineate three distinct intra-tumoral habitats based on apparent diffusion coefficient (ADC) and dynamic contrast enhanced (DCE) sequences. GARD estimates that simultaneous integrated boost (SIB) doses of 70 and 60 Gy in 25 fractions to the highest and intermediate radioresistant habitats, while the remaining volume receives standard 50 Gy, would lead to a > 3 fold FPR increase to 24%. Pre-treatment CT guided biopsies of each habitat along with clip placement will be performed for pathologic evaluation, future genomic studies, and response assessment. An mpMRI taken between weeks two and three of treatment will be used for biological plan adaptation to account for tumor response, in addition to an mpMRI after the completion of radiotherapy in addition to pathologic response, toxicity, radiomic response, disease control, and survival will be evaluated as secondary endpoints. Furthermore, liquid biopsy will be performed with mpMRI for future ancillary studies. DISCUSSION: This is the first clinical trial to test a novel genomic-based RT dose optimization (GARD) and to utilize radiomic habitats to identify and target radioresistance regions, as a strategy to improve the outcome of RT-treated STS patients. Its success could usher in a new phase in radiation oncology, integrating genomic and radiomic insights into clinical practice and trial designs, and may reveal new radiomic and genomic biomarkers, refining personalized treatment strategies for STS. TRIAL REGISTRATION: NCT05301283. TRIAL STATUS: The trial started recruitment on March 17, 2022.

Can we lower the platelet threshold of ≥ 50 × 109/L for performing a lumbar puncture safely in patients with hematological malignancies?

Lumbar punctures (LP) are routinely used to administer intrathecal chemotherapy for children and adults with hematologic malignancies. The current guidelines suggest a platelet threshold of ≥ 50 × 109/L prior to LP for intrathecal chemotherapy (ITC). This can be challenging in patients with hematological malignancies who are thrombocytopenic. We conducted a retrospective chart review of 900 LPs for ITC and compared adverse events in patients with a platelet count of ≥ 50 × 109/L and < 50 × 109/L. Cohort 1 included 682 LPs (75.8%) with a pre-procedure platelet count ≥ 50 × 109/L, and cohort 2 included 218 LPs (24.2%) with a pre-procedure platelet count < 50 × 109/L. Cohort 2 was further subdivided into pre-procedure platelet counts of 41 × 109/L-49 × 109/L (n = 43), 31 × 109/L-40 × 109/L (n = 77), 21 × 109/L-30 × 109/L (n = 84), and 11 × 109/L-20 × 109/L (n = 14). Among 900 LP procedures, a pre-procedure platelet count < 50 × 109/L did not demonstrate a higher rate of post-procedure adverse events (6.5% vs 6.8%, p = 0.8237). When cohort 2 was further stratified, the cohort with a pre-procedure platelet count of 21 × 109/L-30 × 109/L had the highest percentage of complications from LP (9.5%) and the highest rates of traumatic taps with observed LP RBC count > 200 (35.7%, p = 0.0015). The rate of red blood cells (RBC) in the CSF was significantly higher in the group with platelets < 50 × 109/L with observed LP RBC count ≥ 200 (31.2% vs 20.5%, p = 0.0016), ≥ 500 (27.1% vs 14.6%, p < 0.0001), and ≥ 1000 (23% vs 11.6%, p < 0.0001). No instances of epidural hematomas were seen. We found no significant difference in bleeding complications between patients undergoing LPs for ITC with a platelet count above or below 50 × 109/L.

Yttrium-90 Radioembolization for Liver-Dominant Metastatic Prostate Cancer: A Case Series.

Transarterial radioembolization (TARE) with yttrium-90 glass microspheres is widely used to treat primary and secondary malignancies in the liver. However, the safety and efficacy of TARE in patients with liver-dominant metastatic castration-resistant prostate cancer (mCRPC) is unknown. A proof-of-concept, retrospective analysis of 7 consecutive patients with liver-dominant mCRPC who were treated with TARE was performed. The median overall survival was 27.2, 32.1, and 108.1 months from the time of TARE, the diagnosis of liver metastases, and initial cancer diagnosis, respectively. The median liver progression-free survival was 7.3 months. No grade 3 or higher adverse effects were noted. TARE was found to be a safe and effective tool for treating patients with liver-dominant mCRPC in this limited cohort.

Safety of CT-Guided Microwave Ablation of Subcardiac Liver Tumors.

PURPOSE: The purpose of this study was to investigate the safety of CT-guided microwave ablation (MWA) of subcardiac hepatic tumors. MATERIALS AND METHODS: This retrospective study included 19 patients (11 males and 8 females, age: 64.0 years (IQR: 58.3, 71.0) who underwent CT-guided MWA of 22 subcardiac tumors from January 2016 through December 2020. The subcardiac tumors consisted of 6 hepatocellular carcinomas and 16 metastases. Hydrodissection or other thermal protection technique was not used during the ablation. Subcardiac ablation was defined as the ablation zone extended ≤ 0.5 cm from myocardium or coronary artery. The safety of MWA of subcardiac tumors was evaluated based on procedural and post-procedural complications and intra-procedural ECG changes. Local tumor progression (LTP) was also analyzed and correlated with tumor and ablation zone sizes. RESULTS: The primary efficacy rate was 100%. The median follow-up was 20.5 months (IQR: 6.0, 29.8). There was no 30-day mortality. One grade 3 complication occurred (severe shoulder and chest pain), and there were 19 events of grade 1 or 2 complications. No instances of cardiac complications or significant procedural ECG changes were observed. There were 22 events of grade 1 and 2 laboratory toxicity and 1 event of grade 3 elevated bilirubin. The LTP was 13.6% at 1 year and 22.7% at 2 years. There was no significant correlation between LTP and tumor or ablation zone sizes. CONCLUSION: CT-guided MWA of subcardiac hepatic tumors is safe, and MWA should be considered as an option for managing subcardiac tumors. LTP rates for MWA of subcardiac tumors may be inferior to ablation of tumors in common location. LEVEL OF EVIDENCE III: Cohort Study.

Role of Radioembolization in the Management of Liver-Dominant Metastatic Renal Cell Carcinoma: A Single-Center, Retrospective Study.

PURPOSE: The management of Renal cell carcinoma (RCC) patients with liver metastases is challenging. Liver-directed therapy, such as Transarterial radioembolization (TARE), is a reasonable option for these patients; however, its safety and efficacy are not well characterized. This study evaluated the safety and efficacy of TARE in patients with liver-dominant metastatic RCC. MATERIALS AND METHODS: This is a retrospective, single-center study. Thirty-eight patients' medical records were reviewed who underwent TARE between January 1, 2009, and December 31, 2019, in a tertiary cancer center. Two were excluded from further analysis. Thirty-six patients received 51 TARE treatments. Median follow-up time was 18.2 months. Imaging data were evaluated using mRECIST or RECIST 1.1 criteria. Toxicities, treatment responses, liver progression-free survival (LPFS), and median overall survival (OS) were calculated. Univariate and multivariate analyses were conducted to reveal predictors of OS. RESULTS: Median OS from TARE was 19.3 months (95% CI, 22.6-47.4) and from diagnosis of liver metastases was 36.5 months (95% CI: 26.4-49.8). Mild, grade 1 or 2, biochemical toxicity developed in 27 patients (75%). Grade 3-4 toxicity was noted in two patients (5.5%). The objective response rate was 89%; the disease control rate was 94% (21 complete response, 11 partial response, two stable disease, and two progressive disease). Univariate and multivariate analyses showed longer survival in patients who had objective response, lower lung shunt fraction, and better baseline liver function. CONCLUSIONS: TARE is safe and effective and led to promising overall survival in patients with liver-dominant metastatic RCC. LEVEL OF EVIDENCE: Level 3, retrospective cohort study.

Effectiveness and Safety of Prostatic Artery Embolization for the Treatment of Lower Urinary Tract Symptoms from Benign Prostatic Hyperplasia in Men with Concurrent Localized Prostate Cancer.

PURPOSE: To assess the effectiveness and safety of prostatic artery embolization (PAE) on lower urinary tract symptoms (LUTS) in the setting of localized prostate cancer (PCa). MATERIALS AND METHODS: This was a retrospective, single-center, institutional review board-approved study from December 2016 to June 2020 of 21 patients (median age, 72; range, 63-83 years) with moderate LUTS and localized PCa. Clinical effectiveness was evaluated at 6 and 12 weeks using International Prostate Symptom Score (IPSS) and quality of life (QoL) improvement. Seventeen patients were scheduled to receive definitive radiotherapy (RT) after PAE; 13 patients completed RT. Short-term imaging signs of oncologic progression were evaluated at 6 and 12 weeks defined by at least one of the following on magnetic resonance imaging: increased Prostate Imaging-Reporting and Data System score of index lesion(s) to at least 4, new extracapsular extension, seminal vesicle involvement, or pelvic lymphadenopathy. Nonparametric Wilcoxon signed-rank test was used for analysis. RESULTS: IPSS improved by a median of 12 (n = 19, P < .0001) and 14 (n = 14, P < .0001) at 6 and 12 weeks, respectively. QoL improved by a median of 2 (n = 19, P < .0001) and 3 (n = 3, P < .0001) at 6 and 12 weeks. Prostate volume decreased by a median of 24% (n = 19, P < .0001) and 36% (n = 12, P = .015) at 6 and 12 weeks. No patients demonstrated disease progression at 6 (n = 16) or 12 (n = 8) weeks by imaging. No patients experienced increased prostate-specific antigen after RT, grade ≥3 adverse events, or greater genitourinary toxicity. CONCLUSIONS: PAE is effective and safe for the treatment of men with LUTS from benign prostatic hyperplasia in the setting of concomitant, localized, non-obstructive PCa.

A Proof-of-Concept Study on the Use of Prostate Artery Embolization Before Definitive Radiation Therapy in Prostate Cancer.

PURPOSE: Prostatic artery embolization (PAE) is an effective therapy for alleviating lower urinary tract symptoms (LUTS) in patients with benign prostatic hyperplasia; however, is not well studied in patients with concurrent prostate cancer (PCa). We demonstrate a proof of concept for PAE before definitive radiation therapy (RT) in patients with PCa. METHODS AND MATERIALS: From December 2017 to July 2019, 9 patients with PCa underwent PAE for the indication of LUTS from benign prostatic hyperplasia with concurrent PCa. Five received radiation and all follow-ups at our institution and were therefore included in the analysis. Median follow-up was 18 months from the time of PAE. Side effects during radiation were quantified using the Common Terminology Criteria for Adverse Events scoring system. Pre- and post-PAE plans were compared in the 5 patients by performing an isovolumetric expansion of the post-PAE plan (treated plan) equivalent to the measured volume reduction after PAE. Patient 1 (PT-01) and PT-02 had prostate RT alone whereas PT-03, PT-04, and PT-05 had prostate with elective nodal coverage RT. Mean doses to organs at risk were compared between the 2 plans. RESULTS: The mean International Prostate Symptom Score reduction after PAE was 13.8 (5.0-30.0; P = .02). The mean prostatic volume reduction after PAE was 23.1% (7.2%-47.7%). There were no Common Terminology Criteria for Adverse Events grade 3 (severe) or higher during radiation. Post-PAE plans in PT-01 and PT-02 had on average 23.2%, 39.8%, and 22.9% decrease in mean dose across the bladder, rectum, and penile bulb, respectively, compared with the pre-PAE plans. There were no appreciable differences in dosimetry in PT03, PT-04, and PT-05 who had nodal coverage. There was no biochemical failure in any of the patients. CONCLUSIONS: We demonstrate a proof of concept that PAE is a clinically significant adjunctive therapy for alleviating LUTS and achieving significant volume reduction before RT, resulting in decreased radiation-related toxicity from RT for PCa.

Evaluation, diagnosis and surveillance of renal masses in the setting of VHL disease.

This brief report focuses on the evaluation and diagnosis of clinically localized renal masses in children and adults with Von Hippel-Lindau (VHL) disease. Counseling considerations pertinent to the urologists, medical oncologists, and multidisciplinary teams involved in the care of these patients are addressed. As practice patterns regarding the evaluation and management of VHL tumors can vary considerably, this report aims to provide guidance on some of the controversies associated with the diagnostic evaluation and initial management of localized renal masses in VHL patients.

Liver tumor ablation in difficult locations: Microwave ablation of perivascular and subdiaphragmatic hepatocellular carcinoma.

AIM: To assess the safety and efficacy of CT-guided microwave ablation (MWA) of hepatocellular carcinoma (HCC) near large blood vessels and the diaphragm by analyzing procedural complications and local tumor progression (LTP). METHODS: From October 2013 through January 2019, 80 patients (54 males and 26 females) with 136 tumors who underwent CT-guided MWA of HCC were included in this retrospective analysis. MWA was performed on 43 perivascular HCC (≤5 mm from a vessel measuring ≥5 mm in diameter), 38 subdiaphragmatic HCC (≤5 mm from diaphragm), and 64 control HCC. Risk factors for local tumor progression (LTP), overall survival, and complications were analyzed using the Chi-square and Cox proportional hazards model methods. RESULTS: The technical success rate of MWA was 100%. Complication incidence was not significantly different between perivascular and control tumors (20.9% vs 10.9%; p = 0.155) or between subdiaphragmatic and control tumors (21.1% vs 10.9%; p = 0.163). The effect of lesion location on LTP disappeared while controlling for age and lesion size. There was no significant difference in median survival time between patients who had only control tumors (38.8 months) compared to patients with at least one perivascular or subdiaphragmatic tumor (42.5 months; p = 0.098). CONCLUSION: CT-guided percutaneous MWA of perivascular and subdiaphragmatic HCC tumors is safe and effective. The local tumor recurrence and survival was not significantly different compared to control tumors.

Prostate Artery Embolization - Adverse Events and Peri-Procedural Management.

As prostate artery embolization (PAE) for treatment of lower urinary tract symptoms attributed to benign prostatic hyperplasia becomes more commonly performed, operator knowledge of the adverse events is essential to inform patient selection, patient preparation, and postprocedural management. The aim of this article is to discuss the incidence, presentation, and management of adverse effects after PAE.

Prostatic Artery Embolization Is Safe and Effective for Medically Recalcitrant Radiation-Induced Prostatitis.

PURPOSE: Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) represents 90% of all chronic prostatitis cases and may occur after radiation therapy (RT) for localized prostate cancer. Medical therapy is effective in approximately 50% of cases, with no therapy demonstrating consistent efficacy in refractory cases. Prostatic artery embolization (PAE) is effective in men with lower urinary tract symptoms and benign prostatic hyperplasia. We report clinical improvement after PAE in a case series of men with CP/CPPS after RT. METHODS AND MATERIALS: Nine men (median age 72 years; range, 61-83 years) with CP/CPPS after RT for prostate cancer underwent PAE. Baseline International Prostate Symptom Score was recorded in 5 patients (median 23; range, 4-26), Chronic Prostatitis Symptom Index score in 6 patients (median 22.5; range, 6-34), and quality of life (QoL) score in 8 patients (median 5; range, 2-6). Median baseline prostate volume was 49 cm3 (range, 22-123 cm3). Patients were followed up at 6 and 12 weeks with QoL, International Prostate Symptom Score, and/or Chronic Prostatitis Symptom Index score and magnetic resonance imaging. RESULTS: Technical success (ie, bilateral embolization) was achieved in 78% (n = 7) of patients with the other 2 patients having undergone unilateral embolization with no major complications. Clinical success was seen in 89% (n = 8) of patients and QoL improved in 78% (n = 7) during the follow-up period. CONCLUSION: CP/CPPS after RT for localized prostate cancer is a highly morbid condition, with medical therapy successful in only 50% of cases. PAE may be a successful therapy for medically recalcitrant CP/CPPS, and further studies are necessary to understand the best patient selection and scenario for PAE in the setting of CP/CPPS.

Transarterial Radioembolization Treatment of Pancreatic Cancer Patients with Liver-Dominant Metastatic Disease Using Yttrium-90 Glass Microspheres: A Single-Institution Retrospective Study.

PURPOSE: To retrospectively evaluate the safety and efficacy of transarterial radioembolization (TARE) with yttrium-90 (90Y)-labeled glass microspheres in pancreatic adenocarcinoma patients with liver-dominant metastatic disease. MATERIALS AND METHODS: This retrospective, single-center study evaluated 26 patients (12 men and 14 women; mean age, 65.5 ± 11.2 years) with liver-dominant metastatic pancreatic cancer who were treated with TARE from April 2010 to September 2017. All patients received systemic chemotherapy before TARE, and 19 received systemic therapy after embolization. Nineteen patients had extrahepatic disease at the time of TARE. Response to treatment was determined by Response Evaluation Criteria in Solid Tumors at 3 months. RESULTS: Median overall survival (OS) from pancreatic cancer diagnosis was 33.0 months (range, 8.5-87.5 months); median OS from diagnosis of liver metastasis was 21.8 months (range, 2.0-86.2 months); and median OS from TARE treatment was 7.0 months (range, 1.0-84.1 months). Grade 1-2 clinical toxicities were noted in 21 patients (80.8%), and 24 patients (92.3%) had grade 1-2 biochemical toxicities. Four patients (15.4%) had grade 3 clinical toxicities, and 6 patients (23.1%) had grade 3 biochemical toxicities. Imaging was available in 22 patients (84.6%) and demonstrated partial response in 1 patient, stable disease in 9 patients, and progressive disease in 12 patients. Improved hepatic progression-free survival was associated in patients younger than 65 years and in those whose carbohydrate antigen 19-9 level decreased or remained stable after treatment. CONCLUSIONS: TARE with 90Y-labeled glass microspheres is safe and led to promising OS in liver-dominant metastatic pancreatic cancer.

Ablation of Intrahepatic Cholangiocarcinoma.

Intrahepatic cholangiocarcinoma is the second most common primary liver cancer but represents only a small portion of all primary liver cancers. At the time of diagnosis, patients are often not surgical candidates due to tumor burden of other comorbidities. In addition, there is a very high rate of tumor recurrence after resection. Local regional therapies, specifically ablative therapies of radiofrequency ablation, microwave ablation, cryoablation, and irreversible electroporation, have proven to be beneficial with other hepatic tumors. The purpose of this review is to provide an overview and update of the medical literature demonstrating ablative therapy as a treatment option for intrahepatic cholangiocarcinoma.

Intrahepatic Cholangiocarcinoma Treated with Transarterial Yttrium-90 Glass Microsphere Radioembolization: Results of a Single Institution Retrospective Study.

PURPOSE: To evaluate the efficacy and safety of transarterial yttrium-90 glass microsphere radioembolization in patients with unresectable intrahepatic cholangiocarcinoma (ICC). MATERIALS AND METHODS: Retrospective review of 85 consecutive patients (41 men and 44 women; age, 73.4 ± 9.3 years) was performed. Survival data were analyzed by the Kaplan-Meier method, Cox regression models, and the log-rank test. RESULTS: Median overall survival (OS) from diagnosis was 21.4 months (95% confidence interval [CI]: 16.6-28.4); median OS from radioembolization was 12.0 months (95% CI: 8.0-15.2). Seven episodes of severe toxicity occurred. At 3 months, 6.2% of patients had partial response, 64.2% had stable disease, and 29.6% had progressive disease. Median OS from radioembolization was significantly longer in patients with Eastern Cooperative Oncology Group (ECOG) scores of 0 and 1 than patients with an ECOG score of 2 (18.5 vs 5.5 months, P = .0012), and median OS from radioembolization was significantly longer in patients with well-differentiated histology than patients with poorly differentiated histology (18.6 vs 9.7 months, P = .012). Patients with solitary tumors had significantly longer median OS from radioembolization than patients with multifocal disease (25 vs. 6.1 months, P = .006). The absence of extrahepatic metastasis was associated with significantly increased median OS (15.2 vs. 6.8 months, P = .003). Increased time from diagnosis to radioembolization was a negative predictor of OS. The morphology of the tumor (mass-forming or infiltrative, hyper- or hypo-enhancing) had no effect on survival. Post-treatment increased cancer antigen 19-9 level, increased international normalized ratio, decreased albumin, increased bilirubin, increased aspartate aminotransferase, and increased Model for End-Stage Liver Disease score were significant predictors of decreased OS. CONCLUSIONS: These data support the therapeutic role of radioembolization for the treatment of unresectable ICC with good efficacy and an acceptable safety profile.

Inferior vena cava filter placement in a left IVC and drainage into duplicated SVC via hemiazygous continuation.

Left-sided inferior vena cava (IVC) is the second most common anatomical anomaly of the IVC. We report a drainage pattern of the left IVC into a left duplicated superior vena cava (SVC) diagnosed during IVC filter placement consultation. The patient was a 66-year-old man with symptomatic hematuria caused by bladder cancer diagnosed with IVC thrombus and a left IVC found on a staging computed tomography urogram. The patient underwent computed tomography pulmonary angiogram, which ruled out pulmonary embolism, but demonstrated hemiazygous continuation of the left IVC above the diaphragm to meet a persistent left SVC (prevalence approximately 0.3%-0.5%) (Kim et al. 1995) [1] emptying into the right atrium via the coronary sinus. We report a novel drainage pattern of the left IVC into a duplicated left SVC via hemiazygous continuation.

Liver-Directed Therapies for Hepatocellular Carcinoma and Intrahepatic Cholangiocarcinoma.

Hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (IHC) are primary liver cancers where all or most of the tumor burden is usually confined to the liver. Therefore, locoregional liver-directed therapies can provide an opportunity to control intrahepatic disease with minimal systemic side effects. The English medical literature and clinical trials were reviewed to provide a synopsis on the available liver-directed percutaneous therapies for HCC and IHC. Locoregional liver-directed therapies provide survival benefit for patients with HCC and IHC compared to best medical treatment and have lower comorbid risks compared to surgical resection. These treatment options should be considered, especially in patients with unresectable disease.

Dynamic contrast-enhanced MRI of the prostate: An intraindividual assessment of the effect of temporal resolution on qualitative detection and quantitative analysis of histopathologically proven prostate cancer.

PURPOSE: To assess the effects of temporal resolution (RT ) in dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) on qualitative tumor detection and quantitative pharmacokinetic parameters in prostate cancer. MATERIALS AND METHODS: This retrospective Institutional Review Board (IRB)-approved study included 58 men (64 ± 7 years). They underwent 3T prostate MRI showing dominant peripheral zone (PZ) tumors (24 with Gleason ≥ 4 + 3), prior to prostatectomy. Continuously acquired DCE utilizing GRASP (Golden-angle RAdial Sparse Parallel) was retrospectively reconstructed at RT of 1.4 sec, 3.7 sec, 6.0 sec, 9.7 sec, and 14.9 sec. A reader placed volumes-of-interest on dominant tumors and benign PZ, generating quantitative pharmacokinetic parameters (ktrans , ve ) at each RT . Two blinded readers assessed each RT for lesion presence, location, conspicuity, and reader confidence on a 5-point scale. Data were assessed by mixed-model analysis of variance (ANOVA), generalized estimating equation (GEE), and receiver operating characteristic (ROC) analysis. RESULTS: RT did not affect sensitivity (R1all : 69.0%-72.4%, all Padj = 1.000; R1GS≥4 + 3 : 83.3-91.7%, all Padj = 1.000; R2all : 60.3-69.0%, all Padj = 1.000; R2GS≥4 + 3 : 58.3%-79.2%, all Padj = 1.000). R1 reported greater conspicuity of GS ≥ 4 + 3 tumors at RT of 1.4 sec vs. 14.9 sec (4.29 ± 1.23 vs. 3.46 ± 1.44; Padj = 0.029). No other tumor conspicuity pairwise comparison reached significance (R1all : 2.98-3.43, all Padj ≥ 0.205; R2all : 2.57-3.19, all Padj ≥ 0.059; R1GS≥4 + 3 : 3.46-4.29, all other Padj ≥ 0.156; R2GS≥4 + 3 : 2.92-3.71, all Padj ≥ 0.439). There was no effect of RT on reader confidence (R1all : 3.17-3.34, all Padj = 1.000; R2all : 2.83-3.19, all Padj ≥ 0.801; R1GS≥4 + 3 : 3.79-4.21, all Padj = 1.000; R2GS≥4 + 3 : 3.13-3.79, all Padj = 1.000). ktrans and ve of tumor and benign tissue did not differ across RT (all adjusted P values [Padj ] = 1.000). RT did not significantly affect area under the curve (AUC) of Ktrans or ve for differentiating tumor from benign (all Padj = 1.000). CONCLUSION: Current PI-RADS recommendations for RT of 10 seconds may be sufficient, with further reduction to the stated PI-RADS preference of RT ≤ 7 seconds offering no benefit in tumor detection or quantitative analysis. LEVEL OF EVIDENCE: 3 J. MAGN. RESON. IMAGING 2017;45:1464-1475.

Prostate Cancer Detection Using Computed Very High b-value Diffusion-weighted Imaging: How High Should We Go?

RATIONALE AND OBJECTIVES: The aim of this study was to assess prostate cancer detection using a broad range of computed b-values up to 5000 s/mm(2). MATERIALS AND METHODS: This retrospective Health Insurance Portability and Accountability Act-compliant study was approved by an institutional review board with consent waiver. Forty-nine patients (63 ± 8 years) underwent 3T prostate magnetic resonance imaging before prostatectomy. Examinations included diffusion-weighted imaging (DWI) with b-values of 50 and 1000 s/mm(2). Seven computed DWI image sets (b-values: 1000, 1500, 2000, 2500, 3000, 4000, and 5000 s/mm(2)) were generated by mono-exponential fit. Two blinded radiologists (R1 [attending], R2 [fellow]) independently evaluated diffusion weighted image sets for image quality and dominant lesion location. A separate unblinded radiologist placed regions of interest to measure tumor-to-peripheral zone (PZ) contrast. Pathologic findings from prostatectomy served as reference standard. Measures were compared between b-values using the Jonckheere-Terpstra trend test, Spearman correlation coefficient, and generalized estimating equations based on logistic regression for correlated data. RESULTS: As b-value increased, tumor-to-PZ contrast and benign prostate suppression for both readers increased (r = +0.65 to +0.71, P ≤ 0.001), whereas anatomic clarity, visualization of the capsule, and visualization of peripheral-transition zone edge decreased (r = -0.69 to -0.75, P ≤ 0.003). Sensitivity for tumor was highest for R1 at b1500-3000 (84%-88%) and for R2 at b1500-2500 (70%-76%). Sensitivities for both pathologic outcomes were lower for both readers at both b1000 and the highest computed b-values. Sensitivity for Gleason >6 tumor was highest for R1 at b1500-3000 (90%-93%) and for R2 at 1500-2500 (78%-80%). The positive predictive value for tumor for R1 was similar from b1000 to 4000 (93%-98%) and for R2 was similar from b1500 to 4000 (88%-94%). CONCLUSIONS: Computed b-values in the range of 1500-2500 s/mm(2) (but not higher) were optimal for prostate cancer detection; b-values of 1000 or 3000-5000 exhibited overall lower performance.