Tc-99m-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 Tc-99m-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. Tc-99m-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 Tc-99m-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 Tc-99m-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 Tc-99m-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.