Comparison of Tc-MIBI planar scintigraphy, SPET/CT and ultrasonography in detection of parathyroid adenoma in patients with primary hyperparathyroidism.

Objective: Primary hyperparathyroidism (PHPT) is a common endocrine disease that is caused by a single adenoma in most of the cases. Surgical management is the mainstay and definitive treatment for parathyroid adenoma (PA). Minimally invasive surgical techniques are as effective as bilateral neck exploration with a lower risk of complications and better cosmetic results in patients with solitary PA. Accurate preoperative localization with imaging modalities is paramount for determining patients candidate for minimally invasive surgery. In this study we aimed to evaluate the diagnostic performance of technetium-99m-methoxyisobutylisonitrile ( Tc-MIBI) planar scintigraphy (PS), single photon emission tomography/computed tomography (SPET/CT) and ultrasonography (US) in patients with PHPT.

Material And Methods: Fifty-eight patients with biochemical evidence of PHPT who underwent pre-operative imaging with parathyroid scintigraphy and US for detection and localization of PA and proceeded to surgery were included in the study. All patients underwent dual phase Tc-sesta MIBI parathyroid scintigraphy (early and delayed planar images and delayed SPET/CT). Data analysis was performed to evaluate the sensitivity, specificity, diagnostic accuracy and PPV of planar images, SPET/CT and US alone and combined US and SPET/CT. Histopathology was used as gold standard.

Results: Sensitivity, specificity, PPV and diagnostic accuracy for detection of PA, 80,4%, 42,8%, 91,1% and 75,8% for PS; 80,4%, 57,7%, 91,1% and 77,5% for delayed SPET/CT; 88,2%, 85,7%, 97,8% and 87,9% for US and 94,1%, 71,4%, 96% and 91,3% for SPET/CT+US. Combined US and SPET/CT has been shown to increase sensitivity and diagnostic accuracy. The overall sensitivity of PS and SPET/CT didn't vary however additional information which is helpful for planning minimally invasive surgery gained from tomographic images.

Conclusion: The combined use of US and SPET/CT has incremental value in accurately localizing PA over either technique alone. In the preoperative assessment of patients with PHPT combination of imaging methods allows selection of patients who would be suitable for minimally invasive surgery.