Prostate cancer is the third leading cause of death and is the most common genitourinary malignancy in men. For the radiological evaluation of the prostate gland, magnetic resonance imaging (MRI) is a valuable imaging modality due to high tissue contrast, multiplanar imaging capabilities and the possibility of tissue characterization. In addition many new techniques in prostate gland MRI are under development and refinement. Recently, diffusion-weighted imaging (DWI) has emerged as a diagnostic technique in the evaluation of various abdominal lesions.
DWI reveals micro-molecular diffusion, which is the Brownian motion of the spins in biologic tissues. Restriction to the molecular diffusion of water in neoplastic tissues can be related both to the greater cellular density in the tissues, generated by the high index of neoplastic replication with a consequent reduction in the width of intercellular spaces, and to the ultrastructural alteration of the normal tissues. In prostate cancer, normal glandular architecture is disrupted, and is replaced by aggregated cancer cells and fibrotic stroma. These changes inhibit the movement of water molecules, with resultant restriction of diffusion and reduction of ADC values in the cancer tissue. The apparent diffusion coefficent (ADC) value has been reported to be useful for quantitatively distinguishing malignancy from benign lesions.
We hereby sought to present DWI features in prostate carcinomas which helped us to attain confident diagnosis of malignancy in renal failure patients wherein contrast scan was difficult. In our cases, the foci of the malignancy in the prostate gland were readily detected on DWI.