Optimal interpretative strategy for preoperative parathyroid scintigraphy.

Purpose: Our objective was to retrospectively compare various scintigraphic methods to determine their relative accuracies and interobserver variabilities in preoperative localization of single-gland disease in patients with primary hyperparathyroidism.
Patients and Methods: We studied 292 patients who underwent preoperative parathyroid scintigraphy and surgical resection between June 2002 and September 2008. Imaging included early and delayed pinhole Tc-MIBI imaging (including anterior oblique images), similar I imaging, and MIBI SPECT. Seven different imaging combinations were assessed as follows: early MIBI only, delayed MIBI only, comparison of dual-phase early and delayed MIBI, visual subtraction of early MIBI and I images, all planar images, SPECT only, and all planar and SPECT images (ALL). Each data set was reviewed by 2 of 4 experienced nuclear physicians without knowledge of clinical information or final diagnosis. Imaging results were compared with surgical outcomes.
Results: The accuracy of ALL imaging for delineating abnormal/normal parathyroid glands by quadrant was 96%, 93%, 95%, and 95% for the 4 readers. The accuracies of visual subtraction of early MIBI and I images and all planar images were not significantly different from ALL for all 4 readers. All planar and SPECT images were significantly more accurate than early MIBI only, delayed MIBI only, or SPECT only for all 4 readers and better than comparison of dual-phase early and delayed MIBI for 3 of 4 readers.
Conclusions: A rigorous combination of multiple imaging approaches yielded high accuracies across multiple readers for localization of a single offending parathyroid gland, but a more limited technique using MIBI/I subtraction imaging with anterior and anterior oblique pinhole images provided similarly high accuracy and limited interobserver variation of accuracy.