Magnetic resonance imaging for prostate cancer: Comparative studies including radical prostatectomy specimens and template transperineal biopsy

The Impact of Histopathological Features of Prostate Cancerous Lesions on Multiparametric Magnetic Resonance Imaging Findings using PI-RADS Version 2

OBJECTIVES

To determine the square measure threshold of prostate cancer lesions in pathological specimens showing PI-RADS categories 3 to 5, and to identify the pathological characteristics of cancerous lesions over the threshold.

METHODS

Cancer foci detected in horizontal sections of specimens were defined as pathological cancerous lesions, in which square measure, lesion location (peripheral or transition zone), Gleason pattern (GP), GP4-5 component percentages, and GP 4 subtypes were assessed. A receiver operating characteristic curve was used to determine the threshold of the square measure of pathological specimens that distinguishes between lesions of PI-RADS categories 1 and 2 and those of 3 to 5. Univariable and multivariable analyses were performed to determine the histopathological features associated with PI-RADS categories 3 to 5.

RESULTS

A total of 100 consecutive patients underwent multiparametric magnetic resonance imaging before robotic-assisted laparoscopic prostatectomy. A total of 1366 pathological cancerous lesions were detected, 217 of which were classified as PI-RADS categories 3 to 5. A square measure of 40 mm² on pathological specimens was the threshold for PI-RADS categories 3 to 5. Of the 415 lesions that were over 40 mm², 211 lesions exhibited PI-RADS categories 1, 2 and 204 lesions exhibited PI-RADS categories 3 to 5. Multiple logistic regression analysis showed that square measure, fused glands, and cribriform glands were independently associated with PI-RADS categories 3 to 5.

CONCLUSION

Cancerous lesions over 40 mm² showing PI-RADS categories 3 to 5 are associated with square measure, fused glands, and cribriform glands.

Contrast-enhanced ultrasound with dispersion analysis for the localization of prostate cancer: correlation with radical prostatectomy specimens

PURPOSE

To determine the value of two-dimensional (2D) contrast-enhanced ultrasound (CEUS) imaging and the additional value of contrast ultrasound dispersion imaging (CUDI) for the localization of clinically significant prostate cancer (csPCa).

METHODS

In this multicentre study, subjects scheduled for a radical prostatectomy underwent 2D CEUS imaging preoperatively. CUDI maps were generated from the CEUS recordings. Both CEUS recordings and CUDI maps were scored on the likelihood of presenting csPCa (any Gleason ≥ 4 + 3 and Gleason 3 + 4 larger than 0.5 mL) by five observers and compared to radical prostatectomy histopathology. An automated three-dimensional (3D) fusion protocol was used to match imaging with histopathology. Receiver operator curve (ROC) analysis was performed per observer and imaging modality.

RESULTS

133 of 216 (62%) patients were included in the final analysis. Average area under the ROC for all five readers for CEUS, CUDI and the combination was 0.78, 0.79 and 0.78, respectively. This yields a sensitivity and specificity of 81 and 64% for CEUS, 83 and 56% for CUDI and 83 and 55% for the combination. Interobserver agreement for CEUS, CUDI and the combination showed kappa values of 0.20, 0.18 and 0.18 respectively.

CONCLUSION

The sensitivity and specificity of 2D CEUS and CUDI for csPCa localization are moderate. Despite compressing CEUS in one image, CUDI showed a similar performance to 2D CEUS. With a sensitivity of 83% at cutoff point 3, it could become a useful imaging procedure, especially with 4D acquisition, improved quantification and combination with other US imaging techniques such as elastography.

Institutional Adoption and Apprenticeship of Fusion Targeted Prostate Biopsy: Does Experience Affect the Cancer Detection Rate?

INTRODUCTION

There are limited data on the learning curve of magnetic resonance imaging/transrectal ultrasound (MRI/TRUS)-fusion targeted prostate biopsies (tBx).

OBJECTIVE

The aim of this study was to investigate the difference in prostate cancer (PCa) detection rate between an experienced urologist and novice resident performing tBx.

METHODS

A total of 183 patients underwent tBx from 2012 to 2016 for a total of 518 tBx cores. Biopsies in this study were performed by an experienced urologist (investigator A) or a novice resident (investigator B). The outcome was the detection of PCa on tBx. Using a multivariable logistic regression model, we estimated odds ratios for the detection of PCa. Inverse probability treatment weighting (IPTW) was used to balance patients' baseline characteristics and compare detection rates of PCa. Before performance of tBx, all patients underwent MRI.

RESULTS

On multivariable logistic regression analysis, investigator experience was associated with a higher odds of detection of PCa (OR = 1.003; 95% confidence interval 1.002-1.006, p = 0.037). After IPTW adjustment, there was no significant difference between the detection rate of investigator A (23%) and investigator B (32%; p = 0.457).

CONCLUSIONS

Data revealed a positive association between investigator experience and the odds of PCa detection, although there was no difference in the detection rates of the investigators.

Dosimetric and Radiobiological Evaluation of Multiparametric MRI-Guided Dose Painting in Radiotherapy of Prostate Cancer

Radiotherapy is one of the treatment options for locally advanced prostate cancer; however, with standard radiation doses, it is not always very effective. One of the strategies to improve the efficiency of radiotherapy is increasing the dose. In this study, to increase tumor local control rates, a new radiotherapy method, known as dose painting (DP), was investigated. To compare 3-dimensional conformal radiotherapy (3D-CRT) and intensity modulated radiotherapy (IMRT) plans with DP for prostate cancer. Twenty-four consecutive patients with locally advanced prostate cancer who underwent an multiparametric-magnetic resonance imaging (MP-MRI) (T₂w, diffusion weighted image, dynamic contrast enhancement, and MRS) scan before a diagnostic biopsy from September 2015 to April 2016 were invited to take part in this study. The tumor local control probability (TCP) values for 3D-CRT, IMRT, and DP techniques were 45, 56, and 77%, respectively. The DP technique had a 37.5 and 71% higher TCP than IMRT and 3D-CRT, and these differences were statistically significant (P = 0.001). The mean normal tissue complication probability (NTCP) values of the organ at risks for 3D-CRT, IMRT, and DP showed that there were statistically significant differences among them in three plans (P = 0.01). DP by contours using MP-MRI is technically feasible. This study evaluated biological modeling based on both MP-MRI defined subvolumes and pathologically defined subvolumes. The MP-MRI-guided DP results in better TCP/NTCP than 3D-CRT and IMRT.

Intraprostatic locations of tumor foci of higher grade missed by diagnostic prostate biopsy among potential candidates for active surveillance

To establish optimal biopsy scheme for selection of candidates for active surveillance (AS) among prostate cancer (PCa) patients, information on topographical distribution of tumor foci of higher grade missed by contemporary biopsy amongst potential candidates of AS would certainly be useful. Thus we analyzed topographic distribution of tumor foci by examining prostatectomy specimens in 444 patients who underwent radical prostatectomy for low risk PCa. Anterior and posterior prostate areas were demarcated by a horizontal line drawn at midpoint of prostatic urethra. Among 444 subjects, patients with upgrading showed relatively higher prevalence of index tumor foci in anterior prostate than those without upgrading, though not reaching statistical significance (p = 0.252). Meanwhile, among 135 (30.4%) patients with very low risk PCa, patients with upgrading showed significantly higher prevalence of index tumor foci in anterior prostate than those without upgrading (52.2% vs 33.8%; p = 0.031). In conclusions, tumor foci of higher grade missed by diagnostic biopsy were mostly located in anterior prostate among very low risk PCa patients. Such finding would be concrete evidence to support the notion that more efforts are needed to increase accuracy in detecting tumor foci in anterior prostate among potential candidates for AS.

Prevention of sepsis prior to prostate biopsy

Purpose

Urosepsis is the most feared complication of transrectal prostate biopsy. The incidence may be increasing from <1% to 2%–3% in contemporary series. Historically, fluoroquinolones have been effective antibiotic prophylaxis to prevent infective complications but antibiotic resistance is increasing. The increase in antibiotic resistance may contribute to reported increases in urosepsis and hospitalization after transrectal biopsy. This article will review other methods clinicians may employ to reduce the incidence of infective complications after prostate biopsy.

Materials and Methods

A systematic review of the literature was conducted using literature databases PubMed and Ovid MEDLINE in August 2015 in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) criteria.

Results

Effective strategies to reduce infective complications after transrectal prostate biopsy include augmented prophylaxis with other antibiotics, rectal swab culture directed antibiotic prophylaxis or a transperineal biopsy approach. Needle disinfection, minimizing the number of biopsy needles and rectal disinfectants may also be of use. These methods may be of particular utility in patients with risk factors for developing urosepsis such as recent antibiotic use and overseas travel.

Conclusions

The scientific literature describes various techniques designed to reduce infective complications caused by prostate biopsy. Clinicians should consider incorporating these novel techniques into their contemporary practice.