Selective venous sampling for localization of hyperfunctioning parathyroid glands

Planar scintigraphy with 123I/99mTc-sestamibi, 99mTc-sestamibi SPECT/CT, 11C-methionine PET/CT, or selective venous sampling before reoperation of primary hyperparathyroidism?

All patients with primary hyperparathyroidism should undergo localization studies before reoperation, but it is not known which method is most accurate. The purpose of this prospective study was to compare the performance of planar scintigraphy with (123)I/(99m)Tc-sestamibi, (99m)Tc-sestamibi SPECT (SPECT/CT), (11)C-methionine PET/CT, and selective venous sampling (SVS) in persistent primary hyperparathyroidism.

METHODS

Twenty-one patients referred for reoperation of persistent hyperparathyroidism were included and investigated with (123)I/(99m)Tc-sestamibi, SPECT/CT (n = 19), (11)C-methionine PET/CT, and SVS (n = 18) before reoperation. All patients had been operated on 1-2 times previously because of hyperparathyroidism. The results of the localization studies were compared with operative findings, histology, and biochemical cure.

RESULTS

Eighteen (86%) of 21 patients were biochemically cured. Nineteen parathyroid glands (9 adenomas, 1 atypical adenoma, and 9 hyperplastic glands) were removed from 17 patients, and 1 patient who was biochemically cured had an unclear histology result. The accuracy for localizing a pathologic parathyroid gland to the correct side of the neck was 59% (95% confidence interval [CI], 36%-79%) for (123)I/(99m)Tc-sestamibi, 19% (95% CI, 5%-42%) for SPECT/CT, 65% (95% CI, 43%-84%) for (11)C-methionine PET/CT, and 40% (95% CI, 19%-65%) for SVS (P < 0.01 for (123)I/(99m)Tc-sestamibi vs. SPECT/CT). The corresponding accuracy for the correct quadrant or more specific site was 48% (95% CI, 27%-69%) for (123)I/(99m)Tc-sestamibi, 14% (95% CI, 3%-36%) for SPECT/CT, 61% (95% CI, 39%-80%) for (11)C-methionine PET/CT, and 25% (95% CI, 9%-49%) for SVS (P < 0.02 for (123)I/(99m)Tc-sestamibi vs. SPECT/CT). In the 3 patients not cured, preoperative (123)I/(99m)Tc-sestamibi and SPECT/CT remained negative, SVS was false predictive in all, and (11)C-methionine PET/CT in 1. (11)C-methionine PET/CT accurately revealed the pathologic gland in 4 of 8 (50%) patients with a negative (123)I/(99m)Tc-sestamibi scan result, all of whom were biochemically cured after reoperation.

CONCLUSION

Planar scintigraphy with (123)I/(99m)Tc-sestamibi performs well in complicated primary hyperparathyroidism and is recommended as first-line imaging before reoperation. (11)C-methionine PET/CT provides valuable additional information if (123)I/(99m)Tc-sestamibi scan results remain negative. (99m)Tc-sestamibi SPECT/CT and SVS provide no additional information, compared with the combined results of (123)I/(99m)Tc-sestamibi and (11)C-methionine PET/CT imaging.

Accuracy of selective venous sampling for intact parathyroid hormone in difficult patients with recurrent or persistent hyperparathyroidism

BACKGROUND

Preoperative noninvasive localization studies of the neck and mediastinum are beneficial before reoperation. However, the role of selective venous sampling (SVS) for parathyroid hormone (PTH) in reoperative parathyroid surgery has never been clearly defined. The purpose of this study was to evaluate the accuracy of SVS when applied selectively to the subset of patients with indeterminate noninvasive localization studies.

METHODS

Between January 1990 and December 2001, 64 of 235 (27%) patients with persistent or recurrent hyperparathyroidism were considered candidates for SVS in addition to noninvasive localization studies. Accuracy of SVS for PTH was retrospectively evaluated.

RESULTS

Successful surgical treatment was achieved in 86% of these patients. SVS for PTH yielded true-positive results in 75% of patients and was not useful for the surgeon in 17% (completely false-positive in 12% and indeterminate in 5%). In 2% of patients, SVS identified successfully 1 gland but failed to locate another abnormal gland. In 6% of patients, the location of the abnormal parathyroid tissue remained unknown, and the patients have persistent hyperparathyroidism.

CONCLUSIONS

We showed that SVS is clinically useful in patients with persistent or recurrent hyperparathyroidism when the noninvasive localization studies do not clearly localize the abnormal parathyroid glands.

Reoperation for suspected primary hyperparathyroidism

A retrospective analysis of 93 patients undergoing 128 re-explorations for persistent or recurrent hypercalcaemia is presented. Seventy-six patients (82 per cent) became normocalcaemic after between one and five reoperations. Nine patients had hypercalcaemia caused by sarcoidosis, familial hypocalciuric hypercalcaemia or metastatic disease, and two had parathyroid carcinoma. Fifteen patients (16 per cent) developed permanent hypoparathyroidism requiring vitamin D and/or calcium therapy and nine had permanent recurrent laryngeal nerve paralysis. Undetected adenomas (41 cases) and inadequate resection in hyperplastic disease (28) were the predominant causes of initial failure. Reoperation for persistent or recurrent hyperparathyroidism restored normocalcaemia in the majority of patients. This 'cure' was achieved at the cost of considerable morbidity and a careful risk-benefit analysis of each patient is recommended before performing reoperative parathyroid surgery.

Pre-operative localization and interventional treatment of parathyroid tumors: when and how?

A variety of diagnostic tests are currently used for parathyroid localization. In patients who have not had previous surgery, none of these are as sensitive or specific for the localization of abnormal parathyroid glands as an experienced surgeon. In these patients, no pre-operative localization procedures are normally needed. Patients who have had previous thyroid or parathyroid surgery require pre-operative localization. Noninvasive imaging procedures (ultrasound, scintigraphy, computed tomography, magnetic resonance imaging) should be performed until an abnormal gland is identified in the same location on at least 2 examinations. The order in which these studies are performed is not important. In the 50% to 70% of patients in whom noninvasive studies are inconclusive, suspicious lesions may be aspirated or biopsied with imaging guidance. If this cannot be done or is nondiagnostic, angiography and, if necessary, parathyroid venous sampling should be done. Intra-operative ultrasound examination of the neck is helpful during re-operations. In selected patients, parathyroid tumors may be ablated by injection of contrast material through an angiographic catheter into the artery supplying the gland, or by percutaneous injection of alcohol into the gland itself. Angiographic ablation is best used for mediastinal glands supplied by the internal thoracic artery or by a descending branch of the inferior thyroid artery. Percutaneous alcohol injection may injure the recurrent laryngeal nerve permanently and should be limited to the rare patient with a neck lesion who has a prohibitive surgical risk. Neither technique is as effective as surgery.

Value of venous catheterization and calcitonin studies in the treatment and management of clinically inapparent medullary thyroid carcinoma

Seventeen patients with medullary thyroid carcinoma (MTC) underwent venous catheterization (VC) for sampling and serum calcitonin (CT) assay. The VC was performed either after an initial treatment in order to detect cervical recurrences and metastases (16 patients) or to prove abnormal CT thyroid secretion before any treatment (one patient). In 16 of the 32 tumoral localizations suspected by VC (50%), a tumoral focus was proven. For selective/peripheral CT gradient value superior to 2.50, 12 localizations of 12 (100%) were proven and for CT gradient value between 1.50 and 2.50, four localizations of 15 (26.6%) were proven. In six patients with exclusive cervical MTC secreting sites, treatment induced a total remission in two cases (12%) and improved in four cases (23%). The authors conclude that VC has a real value to localize MTC secreting sites. A total remission or an improvement can be obtained after treatment when VC detects exclusive cervical tumors.