Diagnostic accuracy of planar, SPECT, and SPECT/CT parathyroid scintigraphy protocols in patients with hyperparathyroidism.

BACKGROUND: Several parathyroid scintigraphy protocols have been used for preoperative localization of hyperfunctioning parathyroid glands in patients with hyperparathyroidism. The aim of this study is to compare the diagnostic accuracy of various parathyroid scintigraphy protocols.

MATERIAL AND METHODS: A retrospective diagnostic accuracy study with histopathology as the reference standard was done. Five imaging protocols were investigated including planar dual tracer Tc-99m pertechnetate/Tc-99m sestamibi (DT), planar dual phase Tc-99m sestamibi (DP), and combined dual tracer dual phase (DTDP) protocols, as well as add-on single photon emission computed tomography (SPECT), and single photon emission computed tomography/computed tomography (SPECT/CT).

RESULTS: A total of 63 patients underwent parathyroid scintigraphy and subsequent parathyroid surgery with a total of 106 excised lesions with histopathological diagnosis. On a lesion-based analysis, sensitivity and specificity (with 95% confidence interval) of protocols were as follows. DT protocol: 69.4% (53.1-82.0%) and 80.0% (49.0-94.3%); DP protocol: 78.6% (52.4-92.4%) and 33.3% (9.7-70.0%); DTDP protocol: 64.7% (47.9-78.5%) and 50.0% (18.8-81.2%); SPECT: 92.3% (66.7-98.6%) and 75.0% (30.1-95.4%); SPECT/CT: 80.0% (49.0-94.3%) and 75.0% (30.1-95.4%). All protocols had perfect sensitivity for detection of parathyroid adenoma whereas SPECT was the most sensitive method for detection of hyperplastic parathyroid glands.

CONCLUSION: Planar parathyroid scintigraphy using the DT protocol has a trend towards being more accurate than DP and DTDP protocols. Additional imaging with SPECT and SPECT/CT had a trend towards being more accurate than planar imaging.