Résumé
Abstract Objective: To compare the predictions of dominant Gleason pattern ≥ 4 or non-organ confined disease with Prostate Imaging Reporting and Data System (PI-RADS v2) with or without proton magnetic resonance spectroscopic imaging (1H-MRSI). Materials and Methods: Thirty-nine men underwent 3-tesla endorectal multiparametric MRI including 1H-MRSI and prostatectomy. Two radiologists assigned PI-RADS v2 and 1H-MRSI scores to index lesions. Statistical analyses used logistic regressions, receiver operating characteristic (ROC) curves, and 2x2 tables for diagnostic accuracies. Results: The sensitivity and specificity of 1H-MRSI and PI-RADS v2 for high-grade prostate cancer (PCa) were 85.7% (57.1%) and 92.9% (100%), and 56% (68.0%) and 24.0% (24.0%). The sensitivity and specificity of 1H-MRSI and PI-RADS v2 for extra-prostatic extension (EPE) were 64.0% (40%) and 20.0% (48%), and 50.0% (57.1%) and 71.4% (64.3%). The area under the ROC curves (AUC) for prediction of high-grade prostate cancer were 0.65 and 0.61 for PI-RADS v2 and 0.72 and 0.70 when combined with 1H-MRSI (readers 1 and 2, p = 0.04 and 0.21). For prediction of EPE the AUC were 0.54 and 0.60 for PI-RADS v2 and 0.55 and 0.61 when combined with 1H-MRSI (p > 0.05). Conclusion: 1H-MRSI might improve the discrimination of high-grade prostate cancer when combined to PI-RADS v2, particularly for PI-RADS v2 score 4 lesions, but it does not affect the prediction of EPE.
Resumo Objetivo: Comparar as predições de tumor com padrão 4 de Gleason dominante ou de tumor com extensão extraprostática utilizando o sistema Prostate Imaging Reporting and Data System (PI-RADS v2), combinado ou não a espectroscopia por ressonância magnética (1H-ERM). Materiais e Métodos: Trinta e nove pacientes submeteram-se a RM de 3 tesla com bobina endorretal, incluindo 1H-ERM, e prostatectomia. Dois radiologistas classificaram as principais lesões identificadas em cada caso utilizando PI-RADS v2 e escores de 1H-ERM. As análises estatísticas incluíram regressões logísticas, curvas receiver operating characteristic (ROC) e tabelas 2x2 para acurácia diagnóstica. Resultados: A sensibilidade e a especificidade da 1H-ERM e do PI-RADS v2 para a detecção de câncer de próstata de alto grau foram 85,7% (57,1%) e 92,9% (100%), e 56% (68%) e 24% (24%). A sensibilidade e a especificidade da 1H-ERM e do PI-RADS v2 para a detecção de extensão extraprostática (EEP) foram 64,0% (40%) e 20% (48%), e 50% (57,1%) e 71,4% (64,3%). As áreas das curvas ROC para a predição de câncer de alto grau foram 0,65 e 0,61 para PI-RADS v2 e 0,72 e 0,70 quando combinado com 1H-ERM (radiologistas 1 e 2, p = 0.04 e 0.21). Para a predição de EEP, as áreas das curvas ROC foram 0,54 e 0,60 para PI-RADS v2 e 0,55 e 0,61 quando combinado com 1H-ERM (p > 0.05). Conclusão: É possível que a 1H-ERM melhore a predição de câncer de alto grau quando combinada ao PI-RADS v2, em particular para lesões que recebem um escore PI-RADS v2 4; entretanto, ela não afeta a predição de EEP.
Résumé
PURPOSE: To retrospectively determine the accuracy of T2-weighted endorectal MR imaging in the detection of prostate cancer after external beam radiation therapy and to investigate the relationship between imaging accuracy and time since therapy. MATERIAL AND METHODS: Institutional review board approval was obtained and the study was HIPPA compliant. We identified 59 patients who underwent 1.5 Tesla endorectal MR imaging of the prostate between 1999 and 2006 after definitive external beam radiation therapy for biopsy-proven prostate cancer. Two readers recorded the presence or absence of tumor on T2-weighted images. Logistic regression and Fishers exact tests for 2x2 tables were used to determine the accuracy of imaging and investigate if accuracy differed between those imaged within 3 years of therapy (n = 25) and those imaged more than 3 years after therapy (n = 34). Transrectal biopsy was used as the standard of reference for the presence or absence of recurrent cancer. RESULTS: Thirty-four of 59 patients (58 percent) had recurrent prostate cancer detected on biopsy. The overall accuracy of T2-weighted MR imaging in the detection cancer after external beam radiation therapy was 63 percent (37/59) for reader 1 and 71 percent for reader 2 (42/59). For both readers, logistic regression showed no difference in accuracy between those imaged within 3 years of therapy and those imaged more than 3 years after therapy (p = 0.86 for reader 1 and 0.44 for reader 2). CONCLUSION: T2-weighted endorectal MR imaging has low accuracy in the detection of prostate cancer after external beam radiation therapy, irrespective of the time since therapy.