Usefulness of 99mTc-SESTAMIBI Scintigraphy in Persistent Hyperparathyroidism after Kidney Transplant

Abstract

Purpose: ^99mTc-labeled sestamibi scintigraphy combined with single-photon emission computed tomography (SPECT) has a high positive predictive value for localizing hyperfunctioning parathyroid lesions in primary hyperparathyroidism (pHPT) but relatively low sensitivity and specificity in secondary hyperparathyroidism (sHPT) and tertiary hyperparathyroidism (tHPT). The purpose of this study is to investigate the usefulness of ^99mTc-sestamibi scintigraphy in persistent hyperparathyroidism after kidney transplant (KT).

Methods: Retrospectively evaluated 50 patients who received parathyroidectomy after KT at a single medical center. The parathyroid lesion with the highest sestamibi uptake intensity of a patient was graded from 0 to 3. Uptake intensity was analyzed in correlation with parathyroid hormone (PTH), calcium, ionized calcium, phosphorus, and vitamin D.

Results: Per-patient analysis, 43 patients had hyperplasia, 6 patients had adenomas, and 1 patient had a carcinoma. Only 3 patients with hyperplasia did not demonstrate any sestamibi uptake in the parathyroid scans. Out of the 148 pathologically confirmed parathyroid lesions, SPECT/CT images were able to identify 89 lesions (60%) and planar images of 71 lesions (48%). The average of sestamibi uptake intensity was mild at grade 1.6. Uptake intensity showed a positive correlation with parathyroid hormone (PTH) level but not with phosphorus, calcium, ionized calcium, or vitamin D levels. The largest lesion showed a high positive predictive value, especially in lesions with a diameter over 1.0 cm.

Conclusions: Regardless of relatively low and less discrete uptake in KT patients, it well depicts the largest and the most hyperfunctioning lesion.

Keywords: Hyperparathyroid; Kidney transplant; Parathyroid; SPECT; Sestamibi.

Fig. 1

Representative images of the visual grading for parathyroid lesion with the highest uptake among 4 parathyroid glands. Grade 0 not depicting any distinctive uptake (a). Grade 1 showing mild uptake lower or equivalent to the soft tissue and bones (b). The image demonstrates grade 1 uptakes in 3 lesions of the right lower, left upper, and left lower parathyroid (circles). Grade 2 uptake in the right lower parathyroid (arrow) showing higher than soft tissue/bone but lower than the salivary glands (c). Grade 3 uptake in the right lower parathyroid (arrow) higher than the salivary glands (d)

Fig. 2

43-year-old woman with a history of a kidney transplant from a deceased donor for IgA nephropathy. The patient had an elevated parathyroid hormone level of 217 pg/mL and hypercalcemia of 10.3 ml/gL. The patient showed homogeneous thyroid uptake on early phase (a) and no significant sestamibi uptake after a washout on delayed phase (b). However, a left lower nodular lesion with mild uptake was seen on delayed SPECT/CT (c). The lesion was confirmed of hyperplasia, and another hyperplasia lesion was discovered in the right upper site, which was not depicted in the sestamibi scan

Fig. 3

52-year-old man with a history of a kidney transplant from a cadaver donor for chronic kidney disease. The patient had an elevated parathyroid hormone level of 318.0 pg/mL and hypercalcemia of 11.9 ml/gL in clinical suspicion of tertiary hyperparathyroidism. The patient showed high (grade 3) uptake intensity in the right superoposterior aspect on sestamibi scan on 15-min (a) and 30-h (b) planar images and SPECT/CT (c). The patient had subtotal parathyroidectomy with half preserving the smallest left lower gland. The right upper parathyroid lesion was the largest lesion out of the 4 (2.3 × 1.6 cm) and unexpectedly confirmed of parathyroid carcinoma by pathology. Other remaining 3 lesions were confirmed of hyperplasia which were not discrete in the sestamibi scan