Dohuble‐phase Parathyroid Scintigraphy in Dogs Using Technetium‐99m‐sestamibi

Abstract

The purpose of this study was to evaluate the utility of double-phase parathyroid scintigraphy using 99mTc-sestamibi for detecting and localizing hyperfunctioning parathyroid glands in hypercalcemic dogs. Fifteen hypercalcemic dogs that underwent parathyroid scintigraphy were included in this study: 3 dogs with hypercalcemia of malignancy, and 12 dogs with hyperfunctioning parathyroid tissue (parathyroid adenoma or parathyroid hyperplasia). The presence of parathyroid adenoma or parathyroid hyperplasia was documented by histopathologic examination. In 3 dogs with hypercalcemia of malignancy, parathyroid scintigraphy was negative for hyperfunctioning parathyroid tissue and the scans were classified as true negative. Parathyroid scintigraphy correctly identified the presence and location of hyperfunctioning parathyroid tissue in only 1 of 6 dogs with a parathyroid adenoma. False positive and false negative results occurred in dogs with parathyroid adenomas. Parathyroid scintigraphy failed to detect hyperfunctioning parathyroid tissue in 5 of 6 dogs with parathyroid hyperplasia and were classified as false negative. False positive results were obtained in the remaining dog with parathyroid hyperplasia. Sensitivity of parathyroid scintigraphy for detecting and localizing hyperfunctioning parathyroid tissue was 11%, specificity was 50%, and overall accuracy was 27%. Positive and negative predictive value were 25% and 27%, respectively. Sensitivity for detection of parathyroid adenomas was 25%, and sensitivity for detection of hyperplastic glands was 0 %. Results of this study indicate that double-phase parathyroid scintigraphy does not appear to have acceptable accuracy in detecting hyperfunctioning parathyroid glands in dogs. Due to the poor sensitivity and specificity of the technique in dogs, parathyroid scintigraphy is not recommended for definitive identification of abnormal parathyroid glands as the cause of hypercalcemia in dogs.

Hypercalcemia and Primary Hyperparathyroidism

“…99m Tc-sestamibi radionuclide scans provide excellent results for localizing parathyroid adenomas in people (O'Dougherty et al, 1992;Taillefer et al, 1992). The poor sensitivity and specificity of parathyroid gland scintigraphy led the authors to conclude that use of this tool could not be recommended (Matwichuk et al, 2000). In a subsequent study, double-phase parathyroid scintigraphy was evaluated in a group of PHPTH dogs with one of 10 having a scan that correlated with surgery.…”

Diagnosing the Etiology of Hypercalcemia in a Dog

“…11,19 Nuclear scintigraphy with technetiumlabeled sestamibi has been used to attempt identification of hyperfunctioning parathyroid glands, but accuracy was found to be poor. 12 For definitive diagnosis of an enlarged parathyroid gland, histopathological examination of an excised gland is required.…”

The Endocrine and Metabolic Systems

“…[3][4][5] Parathyroid gland scintigraphy with technetium 99m sestamibi has poor sensitivity and specificity in the dog. 6 Management. Emergency treatment is necessary for severe hypercalcemia.…”