99m Tc-Sestamibi/ 123 I Subtraction SPECT/CT in Parathyroid Scintigraphy: Is Additional Pinhole Imaging Useful?

OBJECTIVES: This retrospective study evaluated whether the use of additional anterior 99m Tc-sestamibi/123 I pinhole imaging improves the outcome of 99m Tc-sestamibi/123 I subtraction SPECT/CT in parathyroid scintigraphy (PS).

MATERIALS AND METHODS: PS using simultaneous dual-isotope subtraction methods and an acquisition protocol combining SPECT/CT and planar pinhole imaging was performed for 175 patients with primary or secondary hyperparathyroidism. All patients who proceeded to surgery with complete postsurgery laboratory findings were included in this study ( n = 94). SPECT/CT images alone and combined with pinhole images were evaluated.

RESULTS: There were 111 enlarged parathyroid glands of which 104 and 108 glands were correctly visualized by SPECT/CT (seven false positives) or SPECT/CT with pinhole (three false positives), respectively. Both sensitivity and specificity were higher with combined SPECT/CT with pinhole than with SPECT/CT alone (97% versus 94% and 99% versus 98%, resp., not significant). The false-positive rate was 6% with SPECT/CT and decreased to 3% using combined SPECT/CT with pinhole.

CONCLUSION: 99m Tc-sestamibi/123 I subtraction SPECT/CT is a highly sensitive and specific protocol for PS. The use of additional anterior pinhole imaging increases both sensitivity and specificity of PS, although this increase is not statistically significant.