Dual-tracer subtraction parathyroid SPECT using Tc-99m pertechnetate and Tc-99m MIBI

Abstract

The aim of this study was to develop software for dual-tracer subtraction parathyroid SPECT using Tc-99m pertechnetate and Tc-99m MIBI. The software was developed using MATLAB and designed into 3 main steps: image registration, image normalization, and subtraction SPECT. Image registration was performed for all transaxial, coronal and sagittal planes with option to manually adjust slice-by-slice. For normalization, a region of interest (ROI) was manually drawn around the thyroid gland for all transaxial slices of pertechnetate SPECT and the thyroid contours were automatically copied to the MIBI SPECT. A normalization factor was then calculated and used to normalize the pertechnetate SPECT. Finally, MIBI SPECT was subtracted from pertechnetate SPECT to generate subtraction SPECT images. Retrospective data from patients were used to evaluate the software. The abnormal findings on subtraction SPECT were confirmed with the surgical pathologic report used as the gold standard. A total of 10 abnormal glands were surgically removed of which 8 were identified by the subtraction SPECT. These findings corresponded to the pathologic results that confirmed 2 adenomas and 6 hyperplastic glands. However, 2 hyperplastic glands were missed due to their small size. This software is user-friendly, efficient and can be used for dual-tracer subtraction parathyroid SPECT.