Efficacy of additional lateral pinhole and SPECT/CT imaging in dual-phase Tc-99m MIBI parathyroid scintigraphy for localising parathyroid pathologies in patients with primary hyperparathyroidism: a single-institution experience.

Purpose: Parathyroid imaging with dual-phase technetium-99m methoxyisobutrylizonitrile (Tc-99m MIBI) scintigraphy serves as an important prerequisite for the identification of hyperfunctioning parathyroid gland(s) in patients with primary hyperparathyroidism (PHPT) for a successful targeted parathyroidectomy. This study aimed to evaluate the clinical value of additional lateral imaging and single-photon emission computed tomography/computed tomography (SPECT/CT) versus conventional planar imaging for locating parathyroid pathologies in patients with PHPT.
Materials and Methods: A retrospective review was performed on 105 patients who underwent dual-phase Tc-99m MIBI scintigraphy and were surgically treated by parathyroidectomy. Dual-phase Tc-99m-MIBI planar scintigraphy with additional lateral pinhole views and SPECT/CT imaging was performed on a routine basis, as per departmental protocol. Comparison study between imaging modalities was done by patient-based analysis and scintigraphy results were compared with the clinical findings, biochemical markers, and histopathological findings.
Results: Sensitivity and specificity for anterior planar dual-phase Tc-99m MIBI scintigraphy were 78.8 and 80%, respectively. In comparison, lateral pinhole scan and SPECT/CT alone were found to have sensitivities of 85.9 and 90.9%, respectively, with the same specificity. Sensitivity decreased in patients with normocalcaemia and multiglandular disease. The mean adenoma weight and size for true-positive studies were significantly higher than those for false-negative or false-positive studies.
Conclusion: SPECT/CT provided the highest diagnostic accuracy for preoperative identification of parathyroid lesions in PHPT patients. Lateral pinhole imaging offers comparable sensitivity and aids in adenoma localisation when SPECT/CT is unavailable.
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