Diffusion-Weighted Magnetic Resonance Imaging (DW-MRI) as a Diagnostic Method for Prostate Cancer

Prostate cancer is the second most common cancer among men in the world. Due to the slow growth of this cancer, its early detection can lead to definitive treatment and mortality reduction. Based on the lower diagnostic ability of conventional methods, imaging methods have been paid attention in recent years.

The aim of this study was to evaluate the value and accuracy of diffusion MRI in the prostate cancer as a diagnostic method.

This was a descriptive cross-sectional study conducted in a 15-month period in patients with prostate cancer who had lower urinary tract symptoms, high PSA (higher than 4 ng/mL), or an abnormal finding in the digital rectum examination. The patients were evaluated by MRI of the whole prostate gland with T2 weighted and diffusion images. Patients’ conditions were determined by a urologist with standard 12-fold transrectal sonography-guided biopsy of the prostate. Then, by a histologic examination, healthy or cancerous tissues, Gleason score, and the positive blind numbers were determined by a pathologist. In the end, the results were compared.

We observed 80 patients among whom, 25 cases (31.2%) had malignancies in DW-MRI, including 22 cases that had a malignancy in biopsy and three cases whose biopsy indicated the benign pathology. MRI findings in 55 cases (68.7%) were benign (BPH, prostatitis) that in four cases, malignancy was seen in the biopsy. The sensitivity of DW-MRI was 84% and specificity was 94%, indicating a high diagnostic capability for DW-MRI. The positive and negative predictive values of DW-MRI for prostate cancer were 88% and 92%, respectively. We also observed that older age leads to the lower sensitivity of the MRI. Gleason score, PSA level, and tumor burden had a direct relationship with the accuracy of DW-MRI. However, prostate volume did not have a significant relationship with the detection of cancer in MRI.

DW-MRI can be used for better diagnosis and staging of prostate cancer in patients with prostate lesions. Accordingly, it can upgrade cancer diagnosis in patients with negative biopsies and high suspicion of cancer.