Renal cyst mimicking metastasis on a bone scan – advantage of a hybrid imaging

Overview

76-y-old pacient was investigated for the staging of prostate cancer in our department. Whole-body bone scan was performed 2 hours after injection of 550 MBq of ^99mTc -HDP on a gamma camera Optima NM/CT640 with HR collimator. There were a focally increased accumulation in the left iliac bone, in the caudal ribs, in both knees medially (probably due to gonarthrosis) and on the right shank on the whole body scan. (Fig. 1) We performed a SPECT/low dose CT of the pelvis and lumbar spine and of the shank for better specification. The increased accumulation on the right shank was localized on the surface, it is the contamination. (Fig. 2) The focally increased accumulation in the left iliac bone and in the caudal ribs on the planar scan was evident in the kidney cyst. (Fig. 3) Neither in pelvis nor in ribs was detected increased accumulation, these were detected due to shining through to the detectors on the whole-body scan. We concluded that the bone scan is negative without signs of metastases, only with degenerative changes in the lumbar spine and in joints. We described the large kidney cyst on the left side as extra finding of investigation.

Keywords:

SPECT/CT – bone scan – extraosseous accumulation