99mTc-Sestamibi Thigh SPECT/CT Imaging for Assessment of Myopathy in Cerebrotendinous Xanthomatosis With Histopathological and Immunohistochemical Correlation

Purpose The aim of this study was to determine the effectiveness of using 99mTc-sestamibi thigh SPECT/CT imaging for evaluating myopathy in cerebrotendinous xanthomatosis (CTX). Patients and Methods Four genetically proven CTX patients (Family I, Cases I-1 and I-2; Family II, Cases II-1 and II-2) were included. They all underwent muscle biopsies for histopathologic and ultrastructural studies. Immunohistochemical staining for vinculin expression was also performed. 99mTc-sestamibi thigh SPECT/CT imaging was conducted on all 4 CTX patients, and both visual interpretation and muscle-to-background (M/B) ratio count were applied for assessment. Correlation analysis of the imaging findings and results of the ultrastructural and immunohistochemical studies was done. Results In the 99mTc-sestamibi thigh SPECT/CT imaging study, all 4 CTX cases had abnormal scores of visual interpretation and M/B ratios. The ultrastructural features of the skeletal muscle of the 4 CTX cases showed mitochondrial and membrane system abnormalities, with increased depositions of metabolites. They also had abnormal increases in vinculin expression after immunohistochemical staining of the skeletal muscle. Conclusions This is the first report on the use of 99mTc-sestamibi thigh SPECT/CT imaging to assess the mitochondrial status of CTX. The imaging findings may have a correlation with the ultrastructural and immunohistochemical findings on skeletal muscle. Although the 99mTc-sestamibi thigh SPECT/CT imaging is not specific for CTX, this noninvasive in vivo assessment can be an important tool for the detection and follow-up study of skeletal muscle involvement in CTX.