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

Abstract

Objectives This retrospective study evaluated whether the use of additional anterior 99mTc-sestamibi/123I pinhole imaging improves the outcome of 99mTc-sestamibi/123I 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 99mTc-sestamibi/123I 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.

The role of combined techniques of scintigraphy and SPECT/CT in the diagnosis of primary hyperparathyroidism

“…The sensitivity of this method for the diagnosis of parathyroid adenoma is between 50% and 86%. [5–8] The principle consists of the distinct kinetics that Techentium sestamibi has in thyroid and parathyroid glands, revealing hyperfunctioning parathyroid glands in delayed phase. This method is appreciated for simplicity of the technique and low cost.…”

Added Value of Subtraction SPECT/CT in Dual-Isotope Parathyroid Scintigraphy

“…Several previous publications have assessed imaging setups similar to ours. A combination of subtraction pinhole and subtraction SPECT/CT (i.e., our dual/dual setup) has previously been found to have sensitivity similar to ours or higher (81%–98%) and varying specificity (67%–99%) [ 11 , 12 , 13 ]. In these studies the removed parathyroid glands were somewhat larger than in the present study (average size 700–1420 mg, compared to 544 mg in the present study) which, as mentioned, would likely increase sensitivity.…”

“…Due to the limited sensitivity of the dual/single method, Krčálová et al recommend adding subtraction SPECT/CT (i.e., dual/dual) or 18F-fluorocholin-positron emission tomography / computed tomography (PET/CT) in order to increase sensitivity [ 14 ]. Others have assessed subtraction pinhole alone and/or subtraction SPECT/CT alone, the former with reported sensitivities and specificities of 75%–88% and 90% respectively, and the latter sensitivity of 86%–95% and specificity 98%–100% [ 6 , 13 ]. In our experience very small HPG’s may be visible only on pinhole images, therefore we do not recommend omitting planar pinhole imaging.…”