Improved detection and reduced biopsies: the effect of a multiparametric magnetic resonance imaging-based triage prostate cancer pathway in a public teaching hospital

PURPOSE

Multiparametric magnetic resonance imaging (mpMRI) improves clinically significant prostate cancer (csPCa) detection by facilitating targeted biopsy (cognitive, fusion technology, or in-gantry MRI guidance) and reducing negative biopsies. This study sought to describe the feasibility of introducing an mpMRI-based triage pathway, including diagnostic performance, applicability to training, and cost analysis.

METHODS

An observational retrospective cohort study of consecutive patients attending a large public tertiary referral training hospital who underwent mpMRI for suspicion of prostate cancer was considered. Standard clinical, MRI-related, histopathological, and financial parameters were collected for analysis of biopsy avoidance, diagnostic accuracy of biopsy approach, and operator (consultant and resident/registrar) and logistical (including financial) feasibility.

RESULTS

653 men underwent mpMRI, of which 344 underwent prostate biopsy resulting in a 47% biopsy avoidance rate. Overall, 240 (69.8%) patients were diagnosed with PCa, of which 208 (60.5%) were clinically significant, with higher rates of csPCa observed for higher PIRADS scores. In patients who underwent both systematic and targeted biopsy (stTPB), targeted cores detected csPCa in 12.7% and 16.6% in more men than systematic cores in PIRADS 5 and 4, respectively, whereas systematic cores detected csPCa in 5% and 3.2% of patients, where targeted cores did not. A high standard of performance was maintained across the study period and the approach was shown to be cost effective.

CONCLUSIONS

Introdution of an mpMRI-based triage system into a large public tertiary teaching hospital is feasible, cost effective and leads to high rates of prostate cancer diagnosis while reducing unnecessary biopsies and detection of insignificant PCa.

Application of an unsupervised multi-characteristic framework for intermediate-high risk prostate cancer localization using diffusion-weighted MRI

PURPOSE

The aim of this proof-of-concept work is to propose an unsupervised framework that combines multiple parameters, in "positive-if-all-positive" manner, from different models to localize tumors.

METHODS

A voxel-by-voxel analysis of the DW-MRI images of whole prostate was performed to obtain parametric maps for D*, D, f, and K using the IVIM and kurtosis models. Ten patients with moderate or high-risk prostate cancer were included in study. The mean age and serum PSA for these 10 patients were 65years (range 54-78) and 21.9ng/mL (range 4.84-44.81), respectively. These patients were scanned using a DW spin-echo sequence with echo-planar readout with 16 equidistantly spaced b-values in the range of 0-2000s/mm² (TE=58ms; TR=3990ms; spatial resolution 2.19×2.19×2.73mm³, slices =26, FOV=140×140mm, slice gap =0.27mm, NSA=2).

RESULTS

The proposed framework detected 24 lesions of which 14 were true positive with 58% tumor detection rate on lesion-based analysis with sensitivity of 100%. The mpMRI evaluation (PIRADSv2) identified 12 of 14 true positive lesions with sensitivity of 86%; positive predictive value of mpMRI was 92%. The index lesions were visible on all framework maps and were coded as the most suspicious in 9 of 10 patients.

CONCLUSION

Preliminary results of the proposed framework indicate high patient-based sensitivity with 100% detection rate for identifying moderate-high risk aggressive index lesions.

Use of a Quality Improvement Initiative to Achieve Consistent Reporting of Level of Suspicion for Tumor on Multiparametric Prostate MRI

OBJECTIVE

The purpose of this article is to evaluate the utility of a quality improvement (QI) initiative in achieving long-term adherence to an evolving structured format for reporting the level of suspicion for tumor on prostate MRI examinations.

MATERIALS AND METHODS

The original QI initiative occurred over a 4-month period in 2010, before which prostate MRI was reported using free text. The initiative consisted of development of a section-wide macro, an initial group training session, ordering physician input regarding the structured report's value, subsequent weekly sessions for ongoing review, and timely individualized feedback in instances of nonuse. The initial structured report included pick lists for describing the level of suspicion for tumor as negative, low, medium, or high. Pick lists were modified in 2011 to incorporate a 5-point Likert scale and again in 2015 to incorporate Prostate Imaging Data and Reporting System (PI-RADS) version 2. These refinements were implemented after accelerated training periods. The frequency of reports providing an MRI-based suspicion level during these periods was assessed.

RESULTS

Fifty-five percent of reports provided an MRI-based level of suspicion for tumor before the initiative. For various cohorts evaluated after the initiative (using structured reports based on the low, medium, or high scheme; a numeric Likert scale; or PI-RADS), this frequency improved to 95-100% (p < 0.001). Among reports without a suspicion level, potential confounding factors included marked artifact from hip prosthesis and overt diffuse tumor.

CONCLUSION

The QI initiative achieved excellent adherence in reporting a suspicion level for tumor on prostate MRI examinations. The described components of the initiative were useful for maintaining long-term adherence that persisted after serial modifications to the report lexicon.

Likert score 3 prostate lesions: Association between whole-lesion ADC metrics and pathologic findings at MRI/ultrasound fusion targeted biopsy

BACKGROUND

To assess associations between whole-lesion apparent diffusion coefficient (ADC) metrics and pathologic findings of Likert score 3 prostate lesions at MRI/ultrasound fusion targeted biopsy.

METHODS

This retrospective Institutional Review Board-approved study received a waiver of consent. We identified patients receiving a highest lesion score of 3 on 3 Tesla multiparametric MRI reviewed by a single experienced radiologist using a 5-point Likert scale and who underwent fusion biopsy. A total of 188 score 3 lesions in 158 patients were included. Three-dimensional volumes-of-interest encompassing each lesion were traced on ADC maps. Logistic regression was used to predict biopsy results based on whole-lesion ADC metrics and patient biopsy history. Biopsy yield was compared between metrics.

RESULTS

By lesion, targeted biopsy identified tumor in 22.3% and Gleason score (GS) > 6 tumor in 8.5%, although results varied by biopsy history: biopsy-naïve (n = 80), 20.0%/8.8%; prior negative biopsy (n = 53), 9.4%/1.9%; prior positive biopsy (n = 55): 40.0%/14.5%. Biopsy history, whole-lesion mean ADC, whole-lesion ADC10-25 , and whole-lesion ADC25-50 were each significantly associated with tumor or GS > 6 tumor at fusion biopsy (P ≤ 0.047). In men without prior negative prostate biopsy, whole-lesion ADC25-50  ≤ 1.04*10(-3) mm2 /s achieved 90.0% sensitivity and 50.0% specificity for GS > 6 tumor, which was significantly higher (P < 0.001) than specificity of PSA (17.5%) at identical sensitivity.

CONCLUSION

For score 3 lesions in patients without prior negative biopsy, whole-lesion ADC metrics help detect GS > 6 cancer while avoiding negative biopsies. However, deferral of fusion biopsy may be considered for score 3 lesions in patients with prior negative biopsy (without applying whole-lesion ADC metrics) given exceedingly low (∼ 2%) frequency of GS > 6 tumor in this group.

Prostate whole-mount histology reconstruction and registration to MRI for correlating in-vivo observations with biological findings

Multi-parametric magnetic resonance imaging (mMRI) is the standard exam for prostate cancer diagnosis, staging and risk assessment in current clinical routine. Correlating mMRI in-vivo observations with biological findings from radical prostatectomy specimen would improve the optimal therapy selection. Thus, we proposed a method for reconstructing and registering the prostate whole-mount histology (WMH) to the MRI, considering a thin slicing of the prostatectomy specimen. The method was evaluated on 3 patients, included in a prospective study, for which hematein-eosinsafran and immunohistochemistry stainings were performed. The registration error was assessed by measuring the Euclidean distance between landmarks, previously identified by an expert on both mMRI and histological slices. The mean error was 4:90α1:34 mm. Our method demonstrated promising results for registering prostate WMH to in-vivo mMRI, thus allowing for spatial accurate correlation between radiologic observations and biological information.