Skeletal SPECT/CT of the peripheral extremities.

Objective: Hybrid cameras that combine SPECT and helical CT can be used to correlate scintigraphic information with morphologic information in one imaging session. The purpose of this study was to investigate, in comparison with the value of scintigraphy and SPECT alone, the incremental diagnostic value of skeletal SPECT/CT in the care of patients with pain of the extremities.

Materials And Methods: Seventy-one patients without cancer who had pain in the extremities underwent three-phase bone scintigraphy and SPECT/CT of either the upper (n = 20) or the lower (n = 51) extremities. Planar scintigraphic and SPECT images and planar scintigraphic and SPECT/CT images were interpreted independently from each other. The findings were classified into the following diagnostic categories: normal, trauma, tumor, osteomyelitis, and osteoarthritis.

Results: Four patients had no abnormal bone metabolism or CT abnormality in the extremities. Among 34 lesions classified as osteoarthritis on planar and SPECT images, seven were reclassified as fracture and one as benign tumor at SPECT/CT. Of 15 lesions initially classified as osteomyelitis, four were diagnosed as osteoarthritis, four as fracture, and one as inflammation of the soft tissue only. Of eight diagnoses of fracture with the conventional approach, two were reclassified as osteomyelitis and two as osteoarthritis. In one of 10 patients with the initial diagnosis of a tumorlike lesion, the diagnosis was changed to trauma on the basis of SPECT/CT findings, and in another patient, the diagnosis was changed to osteoarthritis. Overall, SPECT/CT findings led to revision of the diagnostic category in the cases of 23 of 71 patients (p < 0.01).

Conclusion: Compared with bone scintigraphy and SPECT, the use of SPECT/CT increases diagnostic accuracy in the evaluation of orthopedic disorders affecting the extremities.