The Value of Fused SPECT/CT in the Evaluation of Solitary Skull Lesion

Abstract

The aim of this study was to evaluate the role of single photon emission computed tomography and/or computed tomography (SPECT/CT) in differentiating metastatic from benign solitary skull lesions. Consecutive patients who had a SPECT/CT of the head subsequent to a whole-body bone scan (WBS) for the evaluation of a single skull lesion were selected. A single skull lesion on the WBS was further evaluated with SPECT/CT to characterize the lesion. The results of the SPECT/CT were correlated with other radiologic examinations performed within 2 weeks. An average follow-up interval after the SPECT/CT was 8.9 months to correlate with additional radiologic imaging studies and clinical information. A total of 19 lesions in 19 patients were seen on the WBS and 2 additional lesions on the SPECT/CT. All lesions demonstrated focal increased tracer uptake. The SPECT/CT correctly identified 3 out of 3 metastatic lesions and 12 out of 17 benign lesions, that is 71% of lesions were correctly classifised as metastatic or benign lesions. Only 1 patient was classified incorrectly as metastatic lesion with SPECT/CT when it was proven benign by other imaging modalities and follow-up. The sensitivity, specificity, positive and negative predictive values of SPECT/CT images in identifying metastatic lesions were 100%, 92%, 75%, and 100%, respectively. Five lesions remained indeterminate even after the SPECT/CT interpretation and were confirmed benign by other imaging modalities. SPECT/CT can help identify benign versus metastatic solitary skull lesions in most of the patients with high sensitivity and specificity.