摘要
BACKGROUND Bone is one of the common sites of metastasis from prostate carcinoma.Bone scintigraphy(BS)is one of the most sensitive imaging modalities currently used for bone metastatic work-up.Skeletal metastasis in prostate carcinoma commonly involves pelvic bones but rarely involves extrapelvic-extraspinal sites.AIM To retrospectively analyze the BS data to determine the pattern of skeletal metastases in the prostate carcinoma.METHODS This retrospective observational study involves patients with biopsy-proven prostate carcinoma referred for BS for staging assessment.Patients with abnormal BS were evaluated for the pattern of skeletal involvement and data were pre-sented in descriptive format in the form of percentages.RESULTS A total of 150 patients with biopsy-proven prostate cancer who were referred for staging were included in the study.Thirteen of 150 patients(8.67%)had no abnormal uptake on planar images,ruling out metastatic disease.Twenty-four patients(16%)had heterogeneous uptake in the spine with distribution charac-teristic of degenerative disease and no scan pattern of metastatic disease.Thirty patients(20%)had multifocal uptake involving both pelvic and extra pelvic bones on planar images typical for skeletal metastasis and were considered metastatic.Eighty-three out of 150 patients(55.3%)had increased tracer uptake,which was indeterminate,thus,single photon emission computed tomography-computed tomography(SPECT-CT)was acquired,which showed 51 with metastatic disease,31 benign lesions,and one indeterminate finding.Seven of 150 patients had exclusive pelvic bone uptake,which was found to be metastatic in 4/7 patients in SPECT-CT.Fifty six out of 150 patients showed exclusive extrapelvic tracer uptake,of which only 3 had vertebral metastatic disease.None of the patients with increased uptake exclusively in the extrapelvic-extraspinal location was metastatic.CONCLUSION The incidence of exclusive extrapelvic skeletal metastatic disease in prostate carcinoma is 2%(excluding one patient with indeterminate findings).Further,none of the patients in the current study had exclusive extrapelvic-extraspinal metastasis.Thus,exclusive extrapelvic-extraspinal focal abnormality on planar BS carries a very low probability of metastatic disease and hence,further imaging or SPECT-CT can be safely avoided in such cases.
