Keywords:
Cancer, Biopsy, MR, CT, Genital / Reproductive system male, Oncology, Abdomen
Authors:
P. Vivian, S. Dupre; QLD/AU
DOI:
10.1594/ranzcr2016/R-0059
Conclusion
Primary prostate cancer suspected on MRI was detectable on contrast enhanced CT staging scans of the abdomen/pelvis in 41.3% of cases.
Lesions located posterior-laterally in the peripheral zone were more readily detected on CT compared to those located anteriorly,
symmetrically,
diffusely,
or within the transitional zone.
Transition zone lesions were considered harder to detect due to the normal higher density of the transitional zone seen on CT.
(See Fig.
4-9)
The small sample size was the major limitation of the study.
The relationship between lesion visibility on CT and histology could not be accurately investigated in this study due to poor correlation of histology results and lesion location on imaging.
This is an area to be investigated in future research.
Although MRI is superior to CT in the detection of primary prostate cancer,
CT may provide a useful alternative to help direct imaging-guided biopsy of clinically suspected prostate cancer when MRI is not safe (eg.
MRI-incompatible pacemaker),
or not readily accessible.(2)
Targeted MRI-guided biopsy of the prostate is performed at some centres if TRUS biopsy is negative.
MRI-guided biopsies are costly,
time-consuming,
require specific equipment and are technically difficult.(3) If a lesion was also visible on CT then a CT-guided biopsy could potentially be performed,
saving time and money and increase patient access to such a service due to equipment availability.
One recent study has found non-targeted CT-guide transgluteal biopsy of the prostate a viable option in patients without rectal access.(4)
CT scans reviewed in this study were performed in the portal venous phase,
however,
as primary prostate cancer enhances early relative to the surrounding normal parenchyma,
optimal visualisation of lesions on CT would be expected in the arterial phase.(5)
In summary,
primary prostate cancer suspected on MRI can be detected on routine CT abdomen/pelvis scans.
Although MRI is superior to CT in detection of prostate lesions,
there are situations were CT may be the next best option to guide TRUS or CT-guided percutaneous biopsy.
Given the massive number of CT scans that are performed yearly in middle aged and elderly males it is important that radiologists recognise the CT appearance of primary prostate cancer and include the prostate as a ‘review area’ when interpreting all CT abdomen/pelvis scans.
Suspicious findings on CT should prompt further investigation with PSA (prostate-specific antigen) and possibly MRI.