URORADIOLOGY

Imaging Findings

Axial t1w image shows capsular bulge in the right posterior aspect involving the neurovascular bundle, with T2WI axial showing a hypointense area in the peripheral zone on the right side suggestive of malignancy. Image 3 axial stir shows the same finding of a hypointense area in the peripheral zone

Diagnosis

Ca prostate

Discussion:

Adenocarcinoma of the prostate (ACP) is an exceedingly common malignancy. In 1990
ACP became the most frequency cancer diagnosed in American man, surpassing the
frequency of lung cancer for the first time. Prostate cancer is a disease of elderly men, and of all patients with this diagnosis, 75% are 60 to 80 years of age. MRI of the prostate gland with the endorectal surface coil system provides images of the prostatic and periprostatic tissues that are sigificantly more detailed than body coil MRI or transrectal ultrasound. This allows for improved visualization of the seminal vesicles, prostatic capsule, and neurovascular bundles.Although clinical experience with use of endorectal MRI is still some what limited, it appears to be more accurate in identifying advanced disease. The patients Prostate-specific antigen (PSA) value, any prior history of prostitis or radiation therapy, and the location of positive biopsy findings are important pieces of history that should be acknowledged before the interpretation of these images. Although there is still overlap in the distinction between benign and malignant pathologic conditions in the gland on MR images, with the use of a combination of signal intensity behavior, morphology, location, treatment history, and proton MR spectroscopy, a better separation between the two groups can be better made today than 5 years ago. MRI is an emerging technology and new developments are constantly being made at a rapid rate.

Staging Classification

Stage A: tumors that are discovered incidentally on histollogic
examination of prostate tissue from BPH

Stage B: tumors are palpable on rectal examination and are confined
within the boundaries of the prostate

Stage C: tumors which have penetrated the peripheral capsule of the
prostate and may extend cephalid to the seminal vessels or laterally
toward the bony pelvic sidewalls

Stage D: tumors which have spread to the pelvic lymph nodes and have
distant metastases

MR Spectroscopy and the Prostate

Proton, phophorus and carbon MRS have been used in studies both in vitro and in vivo, to associate levels of metabolites with benign or malignant prostate lessions. The levels of phosphocreatine (PCr) and phosphomonesters (PME) can be used to distinguish malignant from benign tissue.

Carcinoma of the prostate is best demonstrated on T2 weighted images, showing a loss of bright signal of both the peripheral zone and seminal vesicles. T1 images are valuable for depicting extra-capsular spread, bone metastases, and lymphadenopathy. Invention of multi-planar fast spin echo seguences had improved the examination of the prostate in four ways: examination is faster, more planes can be covered, TE can be increased to achieve more T2 weighting, phase encodings can be increased to increase resolution, and decreased acquisition time per series reduces motion artifacts

Fat-suppression techniques have been reported to improve the detection of capsular penetration by ACP

Dr. Ashok Raghavan, Manipal Hospital, Bangalore