Current status and future prospective of focal therapy for localized prostate cancer: development of multiparametric MRI, MRI-TRUS fusion image-guided biopsy, and treatment modalities.

Multiparametric magnetic resonance imaging (mpMRI) has been increasingly used to diagnose clinically significant prostate cancer (csPC) because of its usefulness in combination with anatomic and functional data. MRI-targeted biopsy, such as MRI-transrectal ultrasound (TRUS) fusion image-guided prostate biopsy, has high accuracy in the detection and localization of csPC. This novel diagnostic technique contributes to the development of tailor-made medicine as focal therapy, which cures the csPC while preserving the anatomical structures related to urinary and sexual function. In the early days of focal therapy, TRUS-guided systematic biopsy was used for patient selection, and treatment was performed for patients with low-risk PC. With the introduction of mpMRI and mapping biopsy, the treatment range is now determined based on individualized cancer localization. In recent prospective studies, 87.4% of treated patients had intermediate- and high-risk PC. However, focal therapy has two main limitations. First, a randomized controlled trial would be difficult to design because of the differences in pathological features between patients undergoing focal therapy and radical treatment. Therefore, pair-matched studies and/or historical controlled studies have been performed to compare focal therapy and radical treatment. Second, no long-term (≥ 10-year) follow-up study has been performed. However, recent prospective studies have encouraged the use of focal therapy as a treatment strategy for localized PC because it contributes to high preservation of continence and erectile function.

The role of multiparametric magnetic resonance imaging in the diagnosis of granulomatous prostatitis mimicking prostate cancer.

PURPOSE: Aimed to investigate the role of multiparametric magnetic resonance imaging (mp-MRI) in the diagnosis of granulomatous prostatitis caused by intravesical Bacillus Calmette-Guérin (BCG). METHODS: In this prospective, single-center study, 10 male patients who were given intravesical BCG due to intermediate- and high-risk bladder cancer were included. Before transurethral resection of bladder tumors (TURB), all patients were evaluated by mp-MRI, serum prostate-specific antigen (PSA), and digital rectal examination (DRE). Serum PSA levels and DRE findings were evaluated before and after intravesical BCG treatment. Prostate mp-MRI was performed for patients with elevated levels of serum PSA and/or with abnormal DRE findings. Then, MRI fusion + systematic prostate biopsy was performed. Demographic data of the patients before and after intravesical BCG were compared. RESULTS: The average age of the patients was 66.9 years (55-87 years). While PSA was 1.7 ng/ml before intravesical BCG treatment, it was 4.3 ng/ml after intravesical BCG treatment (p = 0.005). PSA density (PSAD) was 0.04 and 0.10 before and after the treatment, respectively (p = 0.012). DRE findings of all patients were normal before the treatment. However, abnormal findings were detected in 80% of them after the treatment (p = 0.008). PI-RADS ≥ 3 lesions were found to be significantly higher in all patients after intravesical BCG (p = 0.004). CONCLUSION: Granulomatous prostatitis is a rare complication of intravesical BCG. High PSA, abnormal DRE, and PI-RADS ≥ 3 lesions detected after intravesical BCG should suggest granulomatous prostatitis and unnecessary biopsies may be avoided.

The effect of delaying transperineal fusion biopsy of the prostate for patients with suspicious MRI findings-Implications for the COVID-19 era.

OBJECTIVE: Image guided biopsies are an integral part of prostate cancer evaluation. The effect of delaying biopsies of suspicious prostate mpMRI lesions is uncertain and clinically relevant during the COVID-19 crisis. We evaluated the association between biopsy delay time and pathologic findings on subsequent prostate biopsy. MATERIALS AND METHODS: After obtaining IRB approval we reviewed the medical records of 214 patients who underwent image-guided transperineal fusion biopsy of the prostate biopsy between 2017 and 2019. Study outcomes included clinically significant (ISUP grade group ≥2) and any prostate cancer on biopsy. Logistic regression was used to evaluate the association between biopsy delay time and outcomes while adjusting for known predictors of cancer on biopsy. RESULTS: The study cohort included 195 men with a median age of 68. Median delay between mpMRI and biopsy was 5 months, and 90% of patients had a ≤8 months delay. A significant association was found between PI-RADS 5 lesions and no previous biopsies and shorter delay time. Delay time was not associated with clinically significant or any cancer on biopsy. A higher risk of significant cancer was associated with older age (P = 0.008), higher PSA (0.003), smaller prostate volume (<0.001), no previous biopsy (0.012) and PI-RADS 5 lesions (0.015). CONCLUSIONS: Our findings suggest that under current practice, where men with PI-RADS 5 lesions and no previous biopsies undergo earlier evaluation, a delay of up to 8 months between imaging and biopsy does not affect biopsy findings. In the current COVID-19 crisis, selectively delaying image-guided prostate biopsies is unlikely to result in a higher rate of significant cancer.

Segmented diffusion-weighted imaging of the prostate: Application to transperineal in-bore 3T MR image-guided targeted biopsy.

OBJECTIVE: This study aims to evaluate the applicability of using single-shot and multi-shot segmented diffusion-weighted imaging (DWI) techniques to support biopsy target localization in a cohort of targeted MRI-guided prostate biopsy patients. MATERIALS AND METHODS: Single-shot echo-planar diffusion-weighted imaging (SS-DWI) and multi-shot segmented (MS-DWI) were performed intra-procedurally on a 3Tesla system in a total of 35 men, who underwent in-bore prostate biopsy inside the scanner bore. Comparisons between SS-DWI and MS-DWI were performed with (in 16 men) and without (in 19 men) parallel coil acceleration (iPAT) for SS-DWI. Overall image quality and artifacts were scored by a radiologist and scores were compared with the Wilcoxon-Mann-Whitney rank test. Correlation between the presence of air and image quality scores was evaluated with Spearman statistics. To quantify distortion, the anteroposterior prostate dimension was measured in SS and MS b=0 diffusion- and T2-weighted images. Signal-to-noise ratio was estimated in a phantom experiment. Agreement and accuracy of targeting based on retrospective localization of restricted diffusion areas in DWI was evaluated with respect to the targets identified using multi-parametric MRI (mpMRI). RESULTS: Compared to SS-DWI without iPAT, the average image quality score in MS-DWI improved from 2.0 to 3.3 (p<0.005) and the artifact score improved from 2.3 to 1.4 (p<0.005). When iPAT was used in SS-DWI, the average image quality score in MS-DWI improved from 2.6 to 3.3 (p<0.05) and the artifact score improved from 2.1 to 1.4 (p<0.01). Image quality (ρ=-0.74, p<0.0005) and artifact scores (ρ=0.77, p<0.0005) both showed strong correlation with the presence of air in the rectum for the SS-DWI sequence without iPAT. These correlations remained significant when iPAT was enabled (ρ=-0.52, p<0.05 and ρ=0.64, p<0.01). For the comparison MS-DWI vs SS-DWI without iPAT, median differences between diffusion- and T2-weighted image gland measurements were 1.1(0.03-10.4)mm and 4.4(0.5-22.7)mm, respectively. In the SS-DWI-iPAT cohort, median gland dimension differences were 2.7(0.4-5.9)mm and 4.2(0.7-8.9)mm, respectively. Out of the total of 89 targets identified in mpMRI, 20 had corresponding restricted diffusion areas in SS-DWI and 28 in MS-DWI. No statistically significant difference was observed between the distances for the targets in the target-concordant SS- and MS-DWI restricted diffusion areas (5.5mm in SS-DWI vs 4.5mm in MS-DWI, p>0.05). CONCLUSIONS: MS-DWI applied to prostate imaging leads to a significant reduction of image distortion in comparison with SS-DWI. There is no sufficient evidence however to suggest that intra-procedural DWI can serve as a replacement for tracking of the targets identified in mpMRI for the purposes of targeted MRI-guided prostate biopsy.

The use of targeted MR-guided prostate biopsy reduces the risk of Gleason upgrading on radical prostatectomy.

PURPOSE: Gleason grading is the strongest predictor of prostate cancer outcome and commonly used to decide for or against the different treatment options. However, Gleason upgrading between systematic transrectal ultrasound-guided prostate biopsy (TRUS-GB) and radical prostatectomy (RPE) has frequently been observed. With respect to the high accuracy of multiparametric MRI (mpMRI) for high-grade cancers and the higher percentage of cancer involvement per biopsy core in targeted MR-guided prostate biopsy (MR-GB), we hypothesized that MR-GB reduces the risk of Gleason upgrading on RPE as compared to the gold standard. The purpose of this study was to compare the rate of Gleason upgrading on RPE for MR-GB, TRUS-GB, and the combination of both biopsy modalities. METHODS: Overall, 52 consecutive patients with RPE had received an mpMRI of the prostate and subsequently underwent targeted MR-GB prior to surgery. All patients underwent an additional TRUS-GB during the same biopsy session. Gleason grading was measured by two different methods: the conventional Gleason score (cGS = primary + secondary pattern) and the highest Gleason pattern (hGP). RESULTS: In relation to TRUS-GB, MR-GB alone showed lower rates of upgrading when comparing the cGS (40.4 vs. 50.0 %) and the hGP (21.2 vs. 32.7 %). The combination of MR-GB and TRUS-GB showed the lowest rates of upgrading (cGS: 28.8 %; hGP: 11.5 %), and compared to TRUS-GB, significantly reduced the risk of upgrading for both measurements of Gleason grading (cGS: OR 0.41, 95 % CL 0.18-0.91, p = 0.0289; hGP: OR 0.27, 95 % CL 0.10-0.75, p = 0.0123). CONCLUSION: MpMRI and targeted MR-GB are useful tools to better characterize and stage the extent of disease, and therefore enable the urologist to better risk-stratify and counsel the patient. The combined use of targeted MR-GB and TRUS-GB presents the least risk of Gleason underestimation.

3D Non-rigid Registration Using Surface and Local Salient Features for Transrectal Ultrasound Image-guided Prostate Biopsy.

We present a 3D non-rigid registration algorithm for the potential use in combining PET/CT and transrectal ultrasound (TRUS) images for targeted prostate biopsy. Our registration is a hybrid approach that simultaneously optimizes the similarities from point-based registration and volume matching methods. The 3D registration is obtained by minimizing the distances of corresponding points at the surface and within the prostate and by maximizing the overlap ratio of the bladder neck on both images. The hybrid approach not only capture deformation at the prostate surface and internal landmarks but also the deformation at the bladder neck regions. The registration uses a soft assignment and deterministic annealing process. The correspondences are iteratively established in a fuzzy-to-deterministic approach. B-splines are used to generate a smooth non-rigid spatial transformation. In this study, we tested our registration with pre- and post-biopsy TRUS images of the same patients. Registration accuracy is evaluated using manual defined anatomic landmarks, i.e. calcification. The root-mean-squared (RMS) of the difference image between the reference and floating images was decreased by 62.6±9.1% after registration. The mean target registration error (TRE) was 0.88±0.16 mm, i.e. less than 3 voxels with a voxel size of 0.38×0.38×0.38 mm3 for all five patients. The experimental results demonstrate the robustness and accuracy of the 3D non-rigid registration algorithm.