Role of TRUS and MRI in the Detection of Prostate Cancer-A Prospective Study

Abstract

Introduction: Prostate cancer ranks second among all cancers affecting men. Common diagnostic tests like Transrectal Ultrasound (TRUS) and Prostate-Specific Antigen (PSA) are suboptimal for diagnostic purpose. Magnetic Resonance Imaging (MRI) has a promising role in detection, guidance for targeted biopsy and staging of prostate cancer. Aim: To evaluate the role of TRUS and MRI in the detection of prostate cancer and to ascertain if any functional parameter or union of parameters is of any utility in detection of prostate cancer. Materials and Methods: A prospective study was conducted which included fifty patients who underwent TRUS and 1.5-T MRI before being subjected toTRUS-guided biopsy. Imaging was compared with histopathological results. The sensitivity, specificity, positive and negative predictive value, positive and negative likelihood ratio for each of the investigation was calculated. Results: The accuracy of the model combining all the imaging variables {T2-weighted imaging (T2WI), MR spectroscopy (MRS), Diffusion-Weighted Imaging (DWI), Apparent Diffusion Coefficient (ADC) and Dynamic Contrast-Enhanced (DCE) MRI} in predicting prostate cancer was 94%, which was higher than the diagnostic accuracy of each variable considered alone (DWI, 92%; ADC, 92%; MRS, 88.0%; DCE-MRI, 92%; and T2WI, 72%). TRUS had a diagnostic accuracy of 80%, sensitivity of 100.0%, specificity of 67.7%, PPV of 65.5% and NPV of 100.0%. Conclusion: TRUS had a high sensitivity and negative predictive value but a low specificity. MRI had both high sensitivity and specificity especially when the combination of functional sequences was used. But, the addition of a third functional technique does not further improve detection. Thus, a limited number of functional sequences are needed in every MRI study for prostatic cancer. However, DWI being the most valuable should be included as one of the sequences.