Should we be looking for prostate carcinoma on CT?

Abstract

Purpose: MRI prostate is becoming routine practice prior to prostate biopsy in the setting of elevated PSA. We have anecdotally found that high-grade prostate lesions identified on MRI are detectable on subsequent contrast enhanced CT abdomen/pelvis staging scans. Although CT is used extensively for assessing nodal and metastatic disease in known prostate cancer, the modality is not considered suitable for diagnosis of primary lesions.1 As such, incidental prostate lesions may be missed or ignored on CT scans performed for other reasons. Prostate cancer has been demonstrated to appear as a focal or diffuse region of contrast enhancement on CT.2 There is currently little research investigating the correlation between CT and MRI findings. By comparing CT with MRI prostate we aim to confirm that high grade prostate cancer can be detected on CT and therefore should be a 'review area' when reporting any CT abdomen/pelvis. Methods and Materials: A retrospective review was undertaken of all MRI prostate scans performed at Nambour General Hospital in the past 24 months, identifying patients with high grade MRI lesions (PIRADS 4 & 5) greater or equal to 1 cm in size. Subsequent staging CT abdomen/pelvis scans (portal venous phase) performed within 6 months of the initial MRI were then examined to determine if an enhancing lesion was detectable at the same site as the MRI lesion. If detected, the average density (HU) of the CT lesion was recorded and compared with the adjacent prostate parenchyma. Histological grading (Gleason score) was also recorded if available. Results: Preliminary results show that, in retrospect, the majority of high-grade prostate lesions diagnosed on MRI are detectable on CT staging scans. Detailed statistical analysis is yet to be performed. Conclusion: Given the preliminary results, we conclude that the detection of focal enhancement within the prostate on CT may represent high-grade prostate cancer and therefore the prostate should be a 'review area' on all CT abdomen/pelvis scans.L612893761 <br />