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An MRI assessment of prostate cancer local recurrence using the PI-RR system: diagnostic accuracy, inter-observer
Paolo Niccolò Franco1,2, Sofia Frade-Santos3,4, Alejandra García-Baizán3
1Department of Radiology, Hospital Universitario de Vigo, Carretera Clara Campoamor 341, 36312, Vigo, Spain. francopaoloniccolo@gmail.com.
Objectives:
The Prostate Imaging for Recurrence Reporting (PI-RR) system has been recently proposed to promote standardisation in the MR assessment of prostate cancer (PCa) local recurrence after radical prostatectomy (RP) and radiation therapy (RT). This study aims to evaluate PI-RR's diagnostic accuracy, assess the inter-observer reliability among readers with variable experience, and correlate imaging results with anatomopathological and laboratory parameters.
Methods:
Patients who underwent a pelvic MRI for suspicion of PCa local recurrence after RP or RT were retrospectively enrolled (October 2017-February 2020). PI-RR scores were independently assessed for each patient by five readers with variable experience in prostate MRI (two senior and three junior radiologists). Biochemical data and histopathological features were collected. The reference standard was determined through biochemical, imaging, or histopathological follow-up data. Reader's diagnostic performance was assessed using contingency tables. Cohen's kappa coefficient (κ) and intraclass correlation coefficient (ICC) were calculated to measure inter-observer reliability.
Results:
The final cohort included 120 patients (median age, 72 years [IQR, 62-82]). Recurrence was confirmed in 106 (88.3%) patients. Considering a PI-RR score ≥ 3 as positive for recurrence, minimum and maximum diagnostic values among the readers were as follows: sensitivity 79-86%; specificity 64-86%; positive predictive value 95-98%; negative predictive value 33-46%; accuracy 79-87%. Regardless of reader's level of experience, the inter-observer reliability resulted good or excellent (κ ranges across all readers: 0.52-0.77), and ICC was 0.8. Prostate-specific antigen (PSA) velocity, baseline-PSA, and trigger-PSA resulted predictive of local recurrence at imaging.
Conclusions:
The PI-RR system is an effective tool for MRI evaluation of PCa local recurrence and facilitates uniformity among radiologists.
Clinical Relevance Statement:
This study confirmed the PI-RR system's good diagnostic accuracy for the MRI evaluation of PCa local recurrences. It showed high reproducibility among readers with variable experience levels, validating it as a promising standardisation tool for assessing patients with biochemical recurrence.
Key Points:
• In this retrospective study, the PI-RR system revealed promising diagnostic performances among five readers with different experience (sensitivity 79-86%; specificity 64-86%; accuracy 79-87%). • The inter-observer reliability among the five readers resulted good or excellent (κ ranges: 0.52-0.77) with an intraclass correlation coefficient of 0.8. • The PI-RR assessment score may facilitate standardisation and generalizability in the evaluation of prostate cancer local recurrence among radiologists.
Insights
The Prostate Imaging for Recurrence Reporting (PI-RR) system shows good accuracy and reliability for MRI detection of prostate cancer recurrence after treatment. This standardized approach improves consistency among radiologists assessing local recurrence.
Area of Science:
- Radiology
- Oncology
- Medical Imaging
Background:
- Standardized MRI assessment is crucial for detecting prostate cancer (PCa) local recurrence post-treatment.
- The Prostate Imaging for Recurrence Reporting (PI-RR) system aims to standardize MRI interpretation for PCa recurrence.
Purpose of the Study:
- Evaluate the diagnostic accuracy of the PI-RR system.
- Assess inter-observer reliability of PI-RR among radiologists with varying experience.
- Correlate PI-RR findings with clinical and pathological data.
Main Methods:
- Retrospective analysis of pelvic MRIs in 120 patients with suspected PCa recurrence.
- Independent PI-RR scoring by five radiologists (two senior, three junior).
- Reference standard established via follow-up data; inter-observer reliability assessed using Cohen's kappa and ICC.
Main Results:
- PI-RR demonstrated good diagnostic performance (sensitivity 79-86%, specificity 64-86%, accuracy 79-87%).
- Excellent inter-observer reliability was observed (kappa 0.52-0.77, ICC 0.8) across all experience levels.
- Prostate-specific antigen (PSA) parameters predicted local recurrence on imaging.
Conclusions:
- The PI-RR system is effective for MRI evaluation of PCa local recurrence.
- It promotes uniformity and standardization in assessing patients with biochemical recurrence.
- PI-RR is a promising tool for improving consistency in prostate MRI interpretation.
