ABSTRACT
BACKGROUND: The accuracy of prostate cancer local staging at the time of diagnosis directly influences patient prognosis and treatment. AIM: To evaluate the diagnostic performance and interobserver variability of mp-MRI in local staging of prostate cancer, using the histopathologic findings at prostatectomy as the reference standard. METHODS: Fifty patients (mean age 64.4±7.2) with biopsy confirmed prostate cancer were included in this prospective study. All patients were examined with mp-MRI before radical prostatectomy and images were read by three independent radiologists. Sensitivity (Se), specificity (Sp), positive predictive value (PPV), negative predictive value (NPV), and accuracy rate were calculated and compared for all three readers. Interobserver agreement was evaluated using Kappa Cohen coefficient of agreement. RESULTS: The overall Se, Sp, PPV, NPV and accuracy rates for detecting extraprostatic tumor extension (EPE) ranged between 76.5-94.1%, 45.5-84.9%, 43.8-76.2%, 83.3-96.6% and 58-88%. For evaluation of seminal vesicle invasion (SVI), the overall Se, Sp, PPV, NPV and accuracy rates ranged between 57.1-85.7%, 86.1-97.7%, 40.0-85.7%, 92.5-97.7% and 82-96%, respectively. The overall Kappa Cohen coefficient of agreement varied between 0.349-0.638 for EPE and between 0.507-0.668 for SVI. CONCLUSIONS: Our results showed that 1.5T mp-MRI is a reliable method for local staging of prostate cancer, with good diagnostic performance in detecting EPE and SVI. The overall interobserver agreement rates between readers with the same level of experience in prostate MRI ranged from fair to good in the evaluation of EPE and from moderate to good for the assessment of SVI.
ABSTRACT
PURPOSE: The purpose of this prospective observational study was to evaluate the diagnostic performance of multiparametric (mp) magnetic resonance imaging (MRI) for prostate cancer detection and to assess the interobserver variability, using the Prostate Imaging Reporting and Data Systems (PI-RADS). METHODS: 50 patients (mean age 68.42±6.58 years) with suspected prostate cancer fulfilling the inclusion criteria and without any exclusion criteria were enrolled. All patients were examined with mp-MRI protocol, as per European Society of Urogenital Radiology (ESUR) guidelines, before systematic transrectal ultrasound (TRUS)-guided biopsy. All examinations were read by three independent radiologists with 3-year experience in prostate MRI. Sensitivity (Se), specificity (Sp), positive predictive value (PPV) and negative predictive value (NPV) were calculated. Interobserver agreement was evaluated using Kappa Cohen coefficient of agreement. RESULTS: mp-MRI and histopathological results of TRUSguided biopsy showed a very good agreement in prostate cancer detection. The overall Se, Sp, PPV and NPV ranged between 93.3-96.7%, 55.0-80.0%, 76.3-87.9% and 88.2-94.1%, respectively. The Kappa Cohen coefficient of interobserver agreement was 0.643 between Readers 1 and 2, 0.664 between Readers 1 and Reader 3 and 0.568 between Readers 2 and 3. CONCLUSIONS: Our results showed a high Se for the detection of prostate cancer with mp-MRI and a high NPV to rule out prostate malignancy. PI-RADS version 2 provides an adequate standardization of mp-MRI, allowing a good level of interobserver agreement.
