Prostate MR Imaging: An Update

Quantitative magnetic resonance imaging in prostate cancer: A review of current technology

Prostate cancer (PCa) imaging forms an important part of PCa clinical management. Magnetic resonance imaging is the modality of choice for prostate imaging. Most of the current imaging assessment is qualitative i.e., based on visual inspection and thus subjected to inter-observer disagreement. Quantitative imaging is better than qualitative assessment as it is more objective, and standardized, thus improving interobserver agreement. Apart from detecting PCa, few quantitative parameters may have potential to predict disease aggressiveness, and thus can be used for prognosis and deciding the course of management. There are various magnetic resonance imaging-based quantitative parameters and few of them are already part of PIRADS v.2.1. However, there are many other parameters that are under study and need further validation by rigorous multicenter studies before recommending them for routine clinical practice. This review intends to discuss the existing quantitative methods, recent developments, and novel techniques in detail.

Utilization trend of prebiopsy multiparametric magnetic resonance imaging and its impact on prostate cancer detection: Real-world insights from a high-volume center in southwest China

BACKGROUND

Data on the utilization and effects of prebiopsy prostate multiparametric magnetic resonance imaging (mpMRI) to support its routine use in real-world setting are still scarce.

OBJECTIVE

To evaluate the change of clinical practice of prebiopsy mpMRI over time, and assess its diagnostic accuracy.

DESIGN, SETTING, AND PARTICIPANTS

We retrospectively analyzed data from 6168 patients who underwent primary prostate biopsy (PBx) between January 2011 and December 2021 and had prostate-specific antigen (PSA) values ranging from 3 to 100 ng/mL.

INTERVENTION

Prebiopsy MRI at the time of PBx.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

We performed general linear regression and to elucidate trends in the annual use of prebiopsy mpMRI and conducted multivariable logistic regression to evaluate the potential benefits of incorporating prebiopsy mpMRI for prostate cancer (PCa) detection.

RESULTS AND LIMITATIONS

The utilization of prebiopsy mpMRI significantly increased from 9.2% in 2011 to 75.0% in 2021 (p < 0.001). In addition, prebiopsy mpMRI significantly reduced negative PBx by 8.6% while improving the detection of clinically significant PCa (csPCa) by 7.0%. Regression analysis showed that the utilization of prebiopsy mpMRI was significantly associated with a 48% (95% confidence interval [CI]: 1.19-1.84) and 36% (95% CI: 1.12-1.66) increased PCa detection rate in the PSA 3-10 ng/mL and 10-20 ng/mL groups, respectively; and a 34% increased csPCa detection rate in the PSA 10-20 ng/mL group (95% CI: 1.09-1.64). The retrospective design and the single center cohort constituted the limitations of this study.

CONCLUSIONS

Our study demonstrated a notable rise in the utilization of prebiopsy mpMRI in the past decade. The adoption of this imaging technique was significantly associated with an increased probability of detecting prostate cancer.

PATIENT SUMMARY

From 2011 to 2021, we demonstrated a steady increase in the utilization of prebiopsy mpMRI among biopsy-naïve men. We also confirmed the positive impact of prebiopsy mpMRI utilization on the detection of prostate cancer.

MRI characteristics of canine prostatic neoplasia

Magnetic resonance imaging (MRI) has been used to evaluate dogs with suspected prostatic neoplasia, however, published studies describing MRI characteristics of canine prostatic neoplasia are currently lacking. The aims of the current retrospective case series study were to describe MRI findings of the pelvic region in dogs with a histopathologic or cytologic diagnosis of prostatic neoplasia. Retrospective analysis of these images was then performed by a board-certified veterinary radiologist for shared imaging characteristics. The most consistent characteristics were heterogeneous hyperintensity of the tumor on T2-weighted images (10/10) and short tau inversion recovery images (10/10), prostatic capsular margin distortion by the tumor (10/10), cavitations (10/10), complete effacement of the prostatic architecture (9/10), neurovascular bundle (NVB) compression or invasion (9/10), heterogeneous isointensity of the tumor on T1-weighted images (9/10), and strong contrast enhancement of the tumor (8/10). Additional features included an overlying pattern of distorted radiating striations (7/10), regional lymphadenomegaly (5/10), mineralization within the mass (5/10), urinary bladder trigone involvement (6/10), and post-prostatic urethral involvement (7/10). These findings supported the use of MRI as an adjunct imaging modality for diagnosis and therapeutic planning of prostatic neoplasia and including prostatic neoplasia as a likely differential diagnosis for dogs with these MRI characteristics.

Roundtable: arguments in support of using multi-parametric prostate MRI protocol

There is increasing evidence to suggest the value of bi-parametric prostate MRI to replace multi-parametric MRI, which includes the dynamic contrast enhancement (DCE) sequence. In this review, we discuss the value of DCE in select scenarios, specifically in resolving equivocal cases, improving the diagnostic accuracy in the inexperienced reader, rescuing exams in the settings of failed T2W and DWI, detecting biochemical recurrence, while imposing minimal to no risk to the patient with respect to IV gadolinium use, specifically group II agents.

Shape Analysis of Peripheral Zone Observations on Prostate DWI: Correlation to Histopathology Outcomes After Radical Prostatectomy

OBJECTIVE. The objective of our study was to subjectively and quantitatively assess shape features of peripheral zone (PZ) tumors at DWI compared with pathologic outcomes. MATERIALS AND METHODS. During the study period, 241 consecutive men with PZ dominant prostate tumors underwent 3-T MRI including DWI before undergoing radical prostatectomy. DW images of these patients were retrospectively assessed by two blinded radiologists. The reviewers assigned Prostate Imaging Reporting and Data System (PI-RADS) shape categories (round or oval, crescentic [i.e., conforming to PZ], linear or wedge-shaped) and segmented tumors for quantitative shape analysis. Discrepancies were resolved by consensus. Comparisons were performed with Gleason score (GS) and pathologic stage. RESULTS. Consensus review results were as follows: 63.9% (154/241) of tumors were round or oval; 22.8% (55/241), crescentic; and 13.3% (32/241), linear or wedge-shaped. Agreement for shape assessment was moderate (κ = 0.41). Round or oval tumors were higher grade (GS 6 = 1.3%, GS 7 = 78.0%, GS ≥ 8 = 20.7%) than crescentic tumors (GS 6 = 9.1%, GS 7 = 74.6%, GS ≥ 8 = 16.3%) and linear or wedge-shaped tumors (GS 6 = 6.3%, GS 7 = 78.1%, GS ≥ 8 = 15.6%) (p = 0.011). In addition, round or oval tumors had higher rates of extraprostatic extension (EPE) and seminal vesicle invasion (SVI) (EPE and SVI: 70.1% and 26.0%) than crescentic tumors (67.3% and 9.1%; p = 0.003) and linear or wedge-shaped tumors (40.6% and 9.4%; p = 0.008). Quantitatively, the shape features termed "circularity" and "roundness" were associated with EPE (p < 0.001 and p = 0.003), SVI (p < 0.001 and p = 0.029), and increasing GS (p = 0.009 and p = 0.021), but there was overlap between groups. CONCLUSION. In this study, approximately 10% of resected PZ tumors were linear or wedge-shaped on DWI. PZ tumors that were judged subjectively and evaluated quantitatively to be round or oval were associated with increased prostate cancer aggressiveness.

Estudio de concordancia entre los resultados de la puntuación de Gleason de biopsias de próstata y los de la prostatectomía radical en pacientes con cáncer de próstata localizado

Introducción. Existen diferencias entre la concordancia de la puntuación de Gleason en biopsias prostática y la patología final.Objetivos. Determinar la concordancia de las puntuaciones de Gleason obtenidas por biopsia de próstata y por prostatectomía radical (PR) en un hospital de IV nivel en Bogotá D.C., Colombia.Materiales y métodos. Estudio retrospectivo de pruebas diagnósticas realizado en un hospital de alta complejidad de Bogotá D.C. Fueron resisados los resultados de las PR y las biopsias prostáticas, clasificando los pacientes según D’Amico y la división por grupos realizada por patólogos. La concordancia diagnóstica se determinó mediante la estimación del coeficiente de Kappa ponderado.Resultados. Se incluyeron 180 pacientes con promedio de edad de 61 años. La exactitud diagnóstica de la puntuación de Gleason dada por biopsia fue de 52%, con supraestadificación del 34% y subestadificación del 14%. El índice Kappa ponderado entre la puntuación de Gleason de la biopsia prostática y la PR fue de 0.37 (p=0.000), y por grupos de 0.4 (p=0.000), con concordancia aceptable para la muestra.Conclusiones. La concordancia de la biopsia de próstata con la PR es baja con tendencia a la supraestadificación, lo que podría tener un impacto negativo en el manejo de los pacientes con cáncer de próstata localizado.

Evolution of prostate MRI: from multiparametric standard to less-is-better and different-is better strategies

Multiparametric magnetic resonance imaging (mpMRI) has become the standard of care to achieve accurate and reproducible diagnosis of prostate cancer. However, mpMRI is quite demanding in terms of technical rigour, patient's tolerability and safety, expertise in interpretation, and costs. This paper reviews the main technical strategies proposed as less-is-better solutions for clinical practice (non-contrast biparametric MRI, reduction of acquisition time, abbreviated protocols, computer-aided diagnosis systems), discussing them in the light of the available evidence and of the concurrent evolution of Prostate Imaging Reporting and Data System (PI-RADS). We also summarised research results on those advanced techniques representing an alternative different-is-better line of the still ongoing evolution of prostate MRI (quantitative diffusion-weighted imaging, quantitative dynamic contrast enhancement, intravoxel incoherent motion, diffusion tensor imaging, diffusional kurtosis imaging, restriction spectrum imaging, radiomics analysis, hybrid positron emission tomography/MRI).

Online Interactive Case-Based Instruction in Prostate Magnetic Resonance Imaging Interpretation Using Prostate Imaging and Reporting Data System Version 2: Effect for Novice Readers

PURPOSE

To assess the effect on reader performance of an interactive case-based online tutorial for prostate magnetic resonance imaging (MRI) interpretation using Prostate Imaging and Reporting Data System (PI-RADS).

METHODS

An educational website was developed incorporating scrollable multiparametric prostate MRI examinations with annotated solutions based on PI-RADS version 2. Three second-year radiology residents evaluated a separate set of 60 prostate MRI examinations both before and after review of the online case material, identifying and scoring dominant lesions. These 60 examinations included 30 benign cases and 30 cases with a dominant lesion demonstrating Gleason score ≥3 + 4 tumor on fusion-targeted biopsy. The readers' pooled performance was compared between the 2 sessions using logistic regression and Wilcoxon signed rank tests.

RESULTS

All readers completed the online material within four-hours. Review of the online material significantly improved sensitivity (from 57.8%-73.3%, P = 0.003) and negative predictive value (from 69.2%-78.2%, P = 0.049), but not specificity (from 70.0%-67.8%, P = 0.692) or positive predictive value (from 59.6%-64.7%, P = 0.389). Reader confidence (1-10 scale; 10 = maximal confidence) also improved significantly (from 5.6 ± 2.7 to 6.3 ± 2.6, P = 0.026). However, accuracy of assigned PI-RADS scores did not improve significantly (from 45.5%-53.3%, P = 0.149).

CONCLUSION

An online interactive case-based website in prostate MRI interpretation improved novice readers' sensitivity and negative predictive value for tumor detection, as well as readers' confidence. This online material may serve as a resource complementing existing traditional methods of instruction by providing a more flexible educational experience among a larger volume of learners. However, further more targeted educational initiatives regarding the proper application of PI-RADS remain warranted.