Metastasis (carcinoma of prostate)

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Clinical History:
This 64 year old man is status post prostatectomy with positive margins and subsequent local regional recurrence, treated with external beam radiation therapy, with further recurrence and subsequent development of disseminated disease.

Diagnosis:
Lumbar vertebral body metastases (prostate carcinoma)

MR Technique:
4 mm sagittal pre-contrast FSE (15 echoes) T2- (without fat saturation), pre-contrast FSE (3 echoes) T1- and post-contrast (with fat saturation) FSE (3 echoes) T1-weighted images are presented, acquired at 1.5 T on a Siemens Espree MR system. Sequence parameters were TR/ TE = 3150/94, 665/9.8 and 835/9.8 respectively. Scan times were 2:28, 3:35 and 4:30 min:sec.

Imaging Findings:
A radiation port is noted extending from a portion of L5 through the sacrum with associated fatty marrow replacement, best seen on the pre-contrast T1-weighted scan. There are multiple focal discrete enhancing lesions within L1, L3, L4, and L5 consistent with metastatic disease. These are best seen on the post-contrast scan with fat saturation, and are less well visualized on the pre-contrast T1-weighted scan, with focal low signal intensity. T2-weighted scans are in general less sensitive for bony metastatic disease, and in this instance were acquired without fat saturation, making the scan extremely poor in terms of sensitivity. There is near complete involvement of the L5 vertebral body, with the radiation port passing through the lower portion of this vertebra. Not illustrated, there were multiple focal mixed blastic and lytic lesions seen within the bilateral sacral ala and iliac bones.

Plain radiographs have poor sensitivity to bony metastases, with detection dependent upon extensive cortical bone destruction. MR is the most sensitive imaging modality in clinical use today. In terms of lytic (those illustrated in the current case) and sclerotic lesions, prostate carcinoma can be of either type, or mixed, but is commonly sclerotic. Breast carcinoma is more commonly lytic, but sclerotic lesions are not uncommon. Lung carcinoma is usually lytic.