A multifaceted approach to quality in the MRI-directed biopsy pathway for prostate cancer diagnosis

PI-QUAL version 2: an update of a standardised scoring system for the assessment of image quality of prostate MRI

Multiparametric MRI is the optimal primary investigation when prostate cancer is suspected, and its ability to rule in and rule out clinically significant disease relies on high-quality anatomical and functional images. Avenues for achieving consistent high-quality acquisitions include meticulous patient preparation, scanner setup, optimised pulse sequences, personnel training, and artificial intelligence systems. The impact of these interventions on the final images needs to be quantified. The prostate imaging quality (PI-QUAL) scoring system was the first standardised quantification method that demonstrated the potential for clinical benefit by relating image quality to cancer detection ability by MRI. We present the updated version of PI-QUAL (PI-QUAL v2) which applies to prostate MRI performed with or without intravenous contrast medium using a simplified 3-point scale focused on critical technical and qualitative image parameters. CLINICAL RELEVANCE STATEMENT: High image quality is crucial for prostate MRI, and the updated version of the PI-QUAL score (PI-QUAL v2) aims to address the limitations of version 1. It is now applicable to both multiparametric MRI and MRI without intravenous contrast medium. KEY POINTS: High-quality images are essential for prostate cancer diagnosis and management using MRI. PI-QUAL v2 simplifies image assessment and expands its applicability to prostate MRI without contrast medium. PI-QUAL v2 focuses on critical technical and qualitative image parameters and emphasises T2-WI and DWI.

Enhancing prostate MRI expertise: educational strategies for radiologists

The adoption of multiparametric MRI (mpMRI) and the Prostate Imaging Reporting and Data System has significantly changed prostate cancer diagnosis and management. These advancements, alongside novel biomarkers and updated International Society of Uropathology grade groups, have improved cancer detection and prognostication. Despite this progress, varying levels of expertise in mpMRI among radiologists have resulted in inconsistent assessments, potentially leading to unnecessary procedures and diminished confidence in the modality. This review assesses the educational landscape for prostate MRI, highlighting available resources for radiologists at all professional stages. It emphasizes the need for targeted educational strategies to bridge knowledge gaps and improve patient care outcomes in prostate cancer management.

Prostate MRI and image quality: The urologist's perspective

The development of different imaging modalities of the prostate has significantly improved tumor detection, patient risk stratification, and quality of care.Among these, multiparametric magnetic resonance imaging (mp-MRI) has emerged as the most sensitive tool.It is useful in the diagnosis, localization, risk stratification, and staging of clinically significant prostate cancer, PCa. As a result, mp-MRI of the prostate is recommended as the initial diagnostic test for men with suspected PCa. A multidisciplinary approach is crucial in the diagnosis and management of prostate cancer and mp-MRI plays a fundamental role in this scenario.While many aspects of image quality certainly fall within the purview of radiology, it is important to recognize that urologists must also be attentive to imaging quality when utilizing mp-MRI to facilitate PCa management. We present our viewpoint as urologists on how image quality impacts the management of men diagnosed with PCa andattempt to identify the factors that impact mp-MRI image quality, consequences of poor image quality, and finally suggestions for improvements.

MRI-informed prostate biopsy: What the radiologist should know on quality in biopsy planning and biopsy acquisition

Quality is currently recognized as the pre-requisite for delivering the clinical benefits expected by magnetic resonance imaging (MRI)-informed prostate biopsy (MRI-i-PB) in patients with a suspicion for clinically significant prostate cancer (csPCa). The "quality chain" underlying MRI-i-PB is multidisciplinary in nature, and depends on several factors related to the patient, imaging technique, image interpretation and biopsy procedure. This review aims at making the radiologist aware of biopsy-related factors impacting on MRI-i-PB quality, both in terms of biopsy planning (threshold for biopsy decisions, association with systematic biopsy and number of targeted cores) and biopsy acquisition (biopsy route, targeting technique, and operator's experience). While there is still space for improvement and better standardization of several biopsy-related procedures, current evidence suggests that high-quality MRI-i-PB can be delivered by acquiring and increased the number of biopsy cores targeted to suspicious imaging findings and perilesional area ("focal saturation biopsy"). On the other hand, uncertainty still exists as to whether software-assisted fusion of MRI and transrectal ultrasound images can outperform cognitive fusion strategy. The role for operator's experience and quality assurance/quality control procedures are also discussed.

Multi-reader evaluation of different image quality scoring systems in prostate MRI

OBJECTIVES

To evaluate different image quality scoring systems in the assessment of factors limiting diagnostic accuracy of prostate MRI.

METHODS

This retrospective IRB-approved study included 281 patients undergoing prostate MRI prior to biopsy. Four readers (2 experienced, 2 novice) independently reviewed all MRI examinations (n = 295) and assigned scores for subjective image quality (1-5; 1:poor, 5:excellent), the PI-QUAL and the PSHS scoring system. The original PI-RADS scores were extracted from the report and transperineal template saturation biopsy served as histopathological reference.

RESULTS

Inter-reader agreement was found to be good, with PSHS showing highest agreement (kappa: 0.65). The PSHS scoring system performed well assessing the influence of image quality on sensitivity of MR for clinically-significant cancer for the experienced readers using a PI-RADS score cut-off ≥ 3/≥4, as did the PI-QUAL scoring system with a PI-RADS cut-off ≥ 4. For the less experienced radiologist, this was true for PSHS (clinically-significant and all cancers) and PI-QUAL scores (clinically-significant cancers) for a PI-RADS score ≥ 3. PSHS scores were positively associated with the detection of clinically-significant cancer based on a PI-RADS cut-off ≥ 4, OR 1.86 (95 % CI 1.22-2.82), and had the highest Somers' D.

CONCLUSIONS

The PSHS scoring system performed well in assessing the effect of image quality on detection rates, as did the PI-QUAL system. Since both systems focus on different aspects of image quality, their incorporation into prostate MRI reports could further enhance standardization and allow for a reliable assessment of image quality as a potential confounder in prostate MRI.

Promoting the use of the PI-QUAL score for prostate MRI quality: results from the ESOR Nicholas Gourtsoyiannis teaching fellowship

OBJECTIVES

The Prostate Imaging Quality (PI-QUAL) score is a new metric to evaluate the diagnostic quality of multiparametric magnetic resonance imaging (MRI) of the prostate. This study assesses the impact of an intervention, namely a prostate MRI quality training lecture, on the participant's ability to apply PI-QUAL.

METHODS

Sixteen participants (radiologists, urologists, physicists, and computer scientists) of varying experience in reviewing diagnostic prostate MRI all assessed the image quality of ten examinations from different vendors and machines. Then, they attended a dedicated lecture followed by a hands-on workshop on MRI quality assessment using the PI-QUAL score. Five scans assessed by the participants were evaluated in the workshop using the PI-QUAL score for teaching purposes. After the course, the same participants evaluated the image quality of a new set of ten scans applying the PI-QUAL score. Results were assessed using receiver operating characteristic analysis. The reference standard was the PI-QUAL score assessed by one of the developers of PI-QUAL.

RESULTS

There was a significant improvement in average area under the curve for the evaluation of image quality from baseline (0.59 [95 % confidence intervals: 0.50-0.66]) to post-teaching (0.96 [0.92-0.98]), an improvement of 0.37 [0.21-0.41] (p < 0.001).

CONCLUSIONS

A teaching course (dedicated lecture + hands-on workshop) on PI-QUAL significantly improved the application of this scoring system to assess the quality of prostate MRI examinations.

KEY POINTS

• A significant improvement in the application of PI-QUAL for the assessment of prostate MR image quality was observed after an educational intervention. • Appropriate training on image quality can be delivered to those involved in the acquisition and interpretation of prostate MRI. • Further investigation will be needed to understand the impact on improving the acquisition of high-quality diagnostic prostate MR examinations.

Prostate MRI Qualification: AJR Expert Panel Narrative Review

Prostate MRI is now established as a first-line investigation for individuals presenting with suspected localized or locally advanced prostate cancer. Successful delivery of the MRI-directed pathway for prostate cancer diagnosis relies on high-quality imaging as well as the interpreting radiologist's experience and expertise. Radiologist certification in prostate MRI may help limit interreader variability, optimize outcomes, and provide individual radiologists with documentation of meeting predefined standards. This AJR Expert Panel Narrative Review summarizes existing certification proposals, recognizing variable progress across regions in establishing prostate MRI certification programs. To our knowledge, Germany is the only country with a prostate MRI certification process that is currently available for radiologists. However, prostate MRI certification programs have also recently been proposed in the United States and United Kingdom and by European professional society consensus panels. Recommended qualification processes entail a multifaceted approach, incorporating components such as minimum case numbers, peer learning, course participation, continuing medical education credits, and feedback from pathology results. Given the diversity in health care systems, including in the provision and availability of MRI services, national organizations will likely need to take independent approaches to certification and accreditation. The relevant professional organizations should begin developing these programs or continue existing plans for implementation.

Artificial Intelligence for Automated Cancer Detection on Prostate MRI: Opportunities and Ongoing Challenges, From the AJR Special Series on AI Applications

Use of prostate MRI has increased greatly in the past decade, primarily in directing targeted prostate biopsy. However, prostate MRI interpretation remains prone to interreader variation. Artificial intelligence (AI) has the potential to standardize detection of lesions on MRI that are suspicious for prostate cancer (PCa). The purpose of this review is to explore the current status of AI for the automated detection of PCa on MRI. Recent literature describing promising results regarding AI models for PCa detection on MRI is highlighted. Numerous limitations of the existing literature are also described, including biases in model validation, heterogeneity in reporting of performance metrics, and lack of sufficient evidence of clinical translation. Challenges related to AI ethics and data governance are also discussed. An outlook is provided for AI in lesion detection on prostate MRI in the coming years, emphasizing current research needs. Future investigations, incorporating large-scale diverse multiinstitutional training and testing datasets, are anticipated to enable the development of more robust AI models for PCa detection on MRI, though prospective clinical trials will ultimately be required to establish benefit of AI in patient management.

Magnetic Resonance Imaging-Targeted Biopsy and Pretherapeutic Prostate Cancer Risk Assessment: a Systematic Review: Biopsie ciblée par Imagerie par résonance magnétique et évaluation pré-thérapeutique du risque de cancer de la prostate : revue systématique

INTRODUCTION

Multiparametric magnetic resonance imaging (MRI) has been included in prostate cancer (PCa) diagnostic pathway and may improve disease characterization. The aim of this systematic review is to assess the added value of MRI-targeted biopsy (TB) in pre-therapeutic risk assessment models over existing tools based on systematic biopsy (SB) for localized PCa.

EVIDENCE ACQUISITION

A systematic search was conducted using Pubmed (Medline), Scopus and ScienceDirect databases according to Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) statement. We included studies through October 2021 reporting on TB in pretherapeutic risk assessment models.

EVIDENCE SYNTHESIS

We identified 24 eligible studies including 24'237 patients for the systematic review. All included studies were retrospective and conducted in patients undergoing radical prostatectomy. Nine studies reported on the risk of extraprostatic extension, seven on the risk of lymph node invasion, three on the risk of biochemical recurrence and nine on the improvement of PCa risk stratification. Overall, the combination of TB with imaging, clinical and biochemical parameters outperformed current pretherapeutic risk assessment models. External validation studies are lacking for certain endpoints and the absence of standardization among TB protocols, including number of TB cores and fusion systems, may limit the generalizability of the results.

CONCLUSION

TB should be incorporated in pretherapeutic risk assessment models to improve clinical decision making. Further high-quality studies are required to determine models' generalizability while there is an urgent need to reach consensus on a standardized TB protocol. Long-term outcomes after treatment are also awaited to confirm the superiority of such models over classical risk classifications only based on SB. © 2022 Elsevier Masson SAS. All rights reserved.

Physically implausible signals as a quantitative quality assessment metric in prostate diffusion-weighted MR imaging

PURPOSE

To provide a quantitative assessment of diffusion-weighted MR images of the prostate through identification of PIDS which clearly represents artifacts in the data. We calculated the percentage and distribution of PIDS in prostate DWI and compare the amount of PIDS between mpMRI images obtained with and without an endorectal coil.

METHODS

This IRB approved retrospective study (from 03/03/2014 to 03/10/2020), included 40 patients scanned with endorectal coil (ERC) and 40 without ER coil (NERC). PIDS contains any voxel where: (1) the diffusion signal increases despite an increase in b-value; and/or (2) apparent diffusion coefficient (ADC) is more than 3.0 μm²/ms (the ADC of pure water at 37 °C and it is physically implausible for any material to have a higher ADC). PIDS for transition zone (TZ) and peripheral zone (PZ) was calculated using an in-house MATLAB program. DWI images were quantitatively inspected for noise, motion, and distortion. T-test was used to compare the difference between PIDS levels in ERC versus NERC and ANOVA to compare the PIDS levels in the anatomic zones. The images were evaluated by a fellowship-trained radiologist in Abdominal Imaging with more than 10 years of experience in reading prostate MRI. This was tested only in prostate in this study.

RESULTS

80 patients (58 ± 8 years old, 80 men) were evaluated. The percentage of voxels exhibiting PIDS was 17.1 ± 8.1% for the ERC cohort and 22.2 ± 15.5% for the NERC cohort. PIDS for NERC versus ERC were not significantly different (p = 0.14). The apex and base showed similar percentages of PIDS in ERC (p = 0.30) and NERC (p = 0.86). The mid (13.8 ± 8.6%) in ERC showed lower values (p = 0.02) of PIDS compared to apex (19.9 ± 11.1%) and base (17.5 ± 8.3%).

CONCLUSION

PIDS maps provide a spatially resolved quantitative quality assessment for prostate DWI. Average PIDS over the entire prostate were similar for the ERC and NERC cohorts, and did not differ significantly across prostate zones. However, for many of the patients, PIDS was focally much higher in specific prostate zones. PIDS assessment can guide Radiologist's evaluation of images and the development of improved DWI sequences.

Inter-reader agreement of the Prostate Imaging Quality (PI-QUAL) score: A bicentric study

PURPOSE

To investigate the inter-reader agreement of the Prostate imaging quality (PI-QUAL) for multiparametric magnetic resonance imaging (mpMRI).

METHODS

We included 66 men who underwent 1.5 T mpMRI in June 2020-July 2020 in center 1, with no exclusion criteria. mpMRI included multiplanar T2-weighted imaging (T2WI), Diffusion-weighted imaging (DWI), and dynamic contrast-enhanced imaging (DCE). Two readers from center 2 (experience <1000 to >1500 examinations), blinded to clinical history but not to acquisition parameters, independently assessed PI-QUAL qualitative/anatomical items of each mpMRI sequence, final PI-QUAL score (1-5), and the Prostate imaging reporting and data system version 2.1 (PI-RADSv2.1) category of the index lesion. Cohen's kappa statistics (k) or prevalence-adjusted-bias-adjusted kappa (PABAK) were used to calculate the inter-reader agreement in assessing the PI-QUAL (1-to-5 scale and 1-2 versus 3 versus 4-5), the diagnostic quality of each mpMRI sequence, qualitative/anatomical items, and PI-RADSv2.1 category.

RESULTS

The inter-reader agreement for PI-QUAL category was moderate upon 1-5 scale (k = 0.55; 95%CI 0.39-0.71) or 1-3 scale (k = 0.51; 95%CI 0.29-0.72), with 90.9% examinations categorized PI-QUAL ≥ 3 by readers. The agreement in assessing a sequence as diagnostic was higher for T2WI (k = 0.76) than DCE (PABAK = 0.61) and DWI (k = 0.46), ranging moderate-to-substantial for most of the items. Readers provided comparable PI-RADSv2.1 categorization (k = 0.88 [excellent agreement]; 95%CI 0.81-0.96), with most PI-RADSv2.1 ≥ 3 assignments found in PI-QUAL ≥ 3 examinations (43/46 by reader 1, and 47/47 by reader 2).

CONCLUSIONS

The reproducibility of PI-QUAL was moderate. Higher PI-QUAL scores were associated with excellent inter-reader agreement for PI-RADSv2.1 categorization.

Deep learning-based artificial intelligence applications in prostate MRI: brief summary

Prostate cancer (PCa) is the most common cancer type in males in the Western World. MRI has an established role in diagnosis of PCa through guiding biopsies. Due to multistep complex nature of the MRI-guided PCa diagnosis pathway, diagnostic performance has a big variation. Developing artificial intelligence (AI) models using machine learning, particularly deep learning, has an expanding role in radiology. Specifically, for prostate MRI, several AI approaches have been defined in the literature for prostate segmentation, lesion detection and classification with the aim of improving diagnostic performance and interobserver agreement. In this review article, we summarize the use of radiology applications of AI in prostate MRI.

PI-QUAL v.1: the first step towards good-quality prostate MRI

• It is mandatory to evaluate the image quality of a prostate MRI scan, and to mention this quality in the report.

• PI-QUAL v1 is an essential starting tool to standardize the evaluation of the quality of prostate MR-images as objectively as possible.

• PI-QUAL will step by step develop into a reliable quality assessment tool to ensure that the first step of the MRI pathway is as accurate as possible.

Comparison of 5 Rectal Preparation Strategies for Prostate MRI and Impact on Image Quality

PURPOSE

To compare 5 different rectal preparation strategies for prostate MRI.

METHODS

This 5-arm quality-assurance study evaluated 56 patients per arm (280 patients) including: no preparation, clear-fluids diet (CFD) beginning at 00:00 hours on the day of MRI, Fleet®-enema, enema + CFD, enema + CFD + IV-antispasmodic agent. The study was powered to 0.80 with alpha-error of 0.05. Three blinded radiologists independently evaluated T2-Weighted (T2W) and Diffusion Weighed Imaging (DWI) for: rectal diameter (maximal AP diameter), rectal content (stool, fluid, gas), rectal motion, T2W/DWI image quality, T2W image sharpness and DWI susceptibility artifact using 5-point Likert scales. Overall comparisons were performed using analysis of variance (ANOVA) and Kruskal-Wallis, with pair-wise comparisons using paired t-tests and Wilcoxon sign-rank tests.

RESULTS

Rectal diameter and amount of gas were lower in enema compared to non-enema groups (p < 0.001), with smallest diameter and least gas in the enema + CFD + IV-antispasmodic group (p = 0.022-<0.001). T2W image quality and sharpness were highest in the enema + CFD groups (p < 0.001) with no difference comparing enema + CFD with/without IV-antispasmodic (p = 0.064, 0.084). Motion artifact was least in enema + CFD + IV-antispasmodic group compared to all other groups (p < 0.001), followed by the enema + CFD group (p = 0.008-<0.001). DWI image quality was highest (p < 0.001) and DWI susceptibility artifact lowest (p < 0.001) in the enema + CFD groups (p < 0.001) and did not differ comparing enema + CFD with/without anti-spasmodic (p = 0.058-0.202).

CONCLUSIONS

Use of enema + clear-fluids diet before prostate MRI yields the highest T2W and DWI image quality with the least DWI artifact. IV-antispasmodic use reduces motion on T2W but does not improve image quality on T2W or DWI, or lessen DWI artifact compared to enema + clear-fluids diet.

Inter-reader agreement of the PI-QUAL score for prostate MRI quality in the NeuroSAFE PROOF trial

Objectives

The Prostate Imaging Quality (PI-QUAL) score assesses the quality of multiparametric MRI (mpMRI). A score of 1 means all sequences are below the minimum standard of diagnostic quality, 3 implies that the scan is of sufficient diagnostic quality, and 5 means that all three sequences are of optimal diagnostic quality. We investigated the inter-reader reproducibility of the PI-QUAL score in patients enrolled in the NeuroSAFE PROOF trial.

Methods

We analysed the scans of 103 patients on different MR systems and vendors from 12 different hospitals. Two dedicated radiologists highly experienced in prostate mpMRI independently assessed the PI-QUAL score for each scan. Interobserver agreement was assessed using Cohen’s kappa with standard quadratic weighting (κw) and percent agreement.

Results

The agreement for each single PI-QUAL score was strong (κw = 0.85 and percent agreement = 84%). A similar agreement (κw = 0.82 and percent agreement = 84%) was observed when the scans were clustered into three groups (PI-QUAL 1–2 vs PI-QUAL 3 vs PI-QUAL 4–5). The agreement in terms of diagnostic quality for each single sequence was highest for T2-weighted imaging (92/103 scans; 89%), followed by dynamic contrast-enhanced sequences (91/103; 88%) and diffusion-weighted imaging (80/103; 78%).

Conclusion

We observed strong reproducibility in the assessment of PI-QUAL between two radiologists with high expertise in prostate mpMRI. At present, PI-QUAL offers clinicians the only available tool for evaluating and reporting the quality of prostate mpMRI in a systematic manner but further refinements of this scoring system are warranted.

Key Points

• Inter-reader agreement for each single Prostate Imaging Quality (PI-QUAL) score (i.e., PI-QUAL 1 to PI-QUAL 5) was strong, with weighted kappa = 0.85 (95% confidence intervals: 0.51 – 1) and percent agreement = 84%.

• Interobserver agreement was strong when the scans were clustered into three groups according to the ability (or not) to rule in and to rule out clinically significant prostate cancer (i.e., PI-QUAL 1-2 vs PI-QUAL 3 vs PI-QUAL 4–5), with weighted kappa = 0.82 (95% confidence intervals: 0.68 – 0.96) and percent agreement = 84%.

• T2-weighted acquisitions were the most compliant with the Prostate Imaging Reporting and Data System (PI-RADS) v. 2.0 technical recommendations and were the sequences of highest diagnostic quality for both readers in 95/103 (92%) scans, followed by dynamic contrast enhanced acquisition with 81/103 (79%) scans and lastly by diffusion-weighted imaging with 79/103 (77%) scans.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00330-021-08169-1.

Current Opinion Regarding Multidisciplinary Cancer Clinic Utilization for the Management of Prostate Cancer

Objectives:

Multidisciplinary cancer clinic (MDC) is an evaluation option for the management of prostate cancer (PCa). The purpose of MDC is to provide the patient with a comprehensive assessment and risk/benefit discussion of all pertinent treatment options. Our objective was to obtain a contemporary measure and analysis of urologists’ opinion regarding PCa MDC.

Material and Methods:

We created a 14-item questionnaire for respondent baseline characteristics, subjective and objective inquiries regarding MDC for PCa management. The survey was distributed through email to members of the Society of Urologic Oncology and the Endourological Society. Data were analyzed using R (R Core team, 2017).

Results:

One hundred and seven (51%) respondents reported participation in MDC; the majority of which were male (97.6%), academic (61.4%) urologists with urologic oncology fellowship training (50%), and >20 years in practice (40.3%). MDC patients were most commonly referrals (78.5%) and with high-risk disease (Gleason sum 8–10) (83.2%). A majority of the respondents felt that MDC was very or extremely beneficial for PCa research (45% and 19%, respectively) and treatment (35% and 20%, respectively). Responses dissuading the use of MDC included lack of infrastructure (41%) and time commitment (21%). On multivariate analysis, urologists with >10 years in practice were less likely to find MDC beneficial in the management of PCa (11–20 years, P = 0.028 and >20 years P = 0.009).

Conclusion:

A contemporary sampling of urologists’ opinion and practice patterns alludes to the benefits that advocate for and the resource demand that hinders routine use of MDC for PCa evaluation. Urologist training and practice environment can affect participation in PCa MDC.