Correlation of parathyroid scanning and anatomy in 261 unselected patients with sporadic primary hyperparathyroidism

Localization of Small Parathyroid Adenomas Using Modified 4-Dimensional Computed Tomography/Ultrasound

Objective. To investigate whether parathyroid gland weight has an impact on the accuracy of preoperative localization of parathyroid adenomas with modified 4 dimensional computed tomography/ultrasound. And to determine if the weight of parathyroid adenomas can be calculated accurately based on the dimensions of the gland on the CT images.

Study Design. Case series with chart review.

Setting. Tertiary care hospital.

Subjects and Methods. One hundred forty-two patients who had a preoperative modified 4-dimensional computed tomography/ultrasound and underwent parathyroidectomy for hyperparathyroidism due to a parathyroid adenoma between 1998 and 2009. Charts were reviewed to identify (1) the sensitivity and specificity for localization of parathyroid adenomas according to gland weight and (2) correlation between preoperative estimate of parathyroid weight and the surgical weight of the parathyroid gland.

Results. Modified 4-dimensional computed tomography/ultrasound displayed 92% sensitivity for localizing adenomas weighing <150 mg to the correct side of the neck (95% confidence interval [CI], 65%-99%), 100% sensitivity for glands weighing 150 to 500 mg (95%-100%), and 98% sensitivity for glands weighing >500 mg (92%-100%). For localization to the correct quadrant of the neck, sensitivity was 75% (95% CI, 47%-91%) for glands weighing <150 mg, 89% (79%-95%) for those weighing 150 to 500 mg, and 94% (85%-97%) for glands weighing >500 mg. A positive correlation was seen between the preoperative weight estimate based on imaging and the operative weight of the gland, with a Pearson correlation coefficient of 0.96.

Conclusion. Modified 4-dimensional computed tomography/ultrasound can closely predict the weight of parathyroid glands preoperatively and has good sensitivity for localization of adenomas, even in glands weighing less than 150 mg.

Weight difference between double parathyroid adenomas is the cause of false-positive IOPTH test after resection of the first lesion

BACKGROUND

Some patients with double parathyroid adenoma show a greater than 50% decline in intraoperative parathyroid hormone (IOPTH) after resection of the first lesion. The present study was designed to test the hypothesis that significant adenoma weight differences may explain this inappropriate decline of IOPTH.

METHODS

We reviewed prospective database records at two tertiary institutions. Patients with a histopathologic diagnosis of double adenoma and no familial history of hyperparathyroidism were included. Diagnosis of double adenoma was confirmed either preoperatively (double uptake), intraoperatively (bilateral exploration), or at reintervention. IOPTH was determined following the Miami protocol. The 10-min postexcision sample was considered as the 0-min sample for IOPTH determinations at the time of resection of the second lesion.

RESULTS

Thirteen patients met the inclusion criteria. After resection of the first lesion, IOPTH failed to decline in four patients and a second adenoma was removed. They had similar weight (404 vs. 598 mg). In nine patients IOPTH showed a false greater than 50% decline. These patients had the largest adenoma removed first (846 +/- 226 mg), and only two had normal PTH serum concentrations 10 min after resection. The second adenoma was always smaller (284 +/- 177 mg; P = 0.02) and its resection either during the same operation (7 cases) or at reoperation (2 cases) led to normalization of IOPTH at 10 min in all cases.

CONCLUSIONS

Two-thirds of patients with double parathyroid adenoma show a false-positive decline of IOPTH after resection of the first adenoma. This appears to be due to the initial removal of the larger lesion.

Primary hyperparathyroidism: role of the preoperative oral calcium loading test in the differential diagnosis between adenoma and hyperplasia

Whereas the sensitivity of the membrane calcium receptors is decreased in parathyroid adenoma, extracellular calcium may reduce parathyroid hormone (PTH) secretion through the protein kinase C pathway in parathyroid hyperplasia. The aim of this study was to determine the role of a preoperative oral calcium loading test in the differential diagnosis between adenoma and hyperplasia. Twenty-two subjects with adenoma (group A, age +/- standard error 56 +/-2 years, female/male 15/7), 10 individuals with hyperplasia (group H, age 54 +/-3, female/male 8/2), and 32 age and gender pair-matched controls (group C) underwent the test. Calcium and PTH were measured before and 60, 120, and 180 min after oral administration of 1 g of calcium (as gluconolactate). Product P was defined as minimal PTH concentration (pg/mL) x maximal calcium concentration (mg/dL) during the test. Ratio R was defined as relative PTH decline/relative calcium increase. The PTH decline during the test in group H was comparable to that of the controls. PTH decline <30%, Product P > 1,100, and Ratio R < 4 diagnosed adenoma with specificity of 100%, 90%, and 100%, respectively. PTH decline >60% diagnosed hyperplasia with specificity of 100%. The total accuracy of the test (65%) was comparable to that of technetium-99 m sestamibi scintigraphy (66%) and better than that of ultrasonography (58%). The test may discriminate patients with sporadic diffuse hyperplasia from individuals with solitary adenoma in cases of primary hyperparathyroidism with an indication for surgery.

Impact of adenoma weight and ectopic location of parathyroid adenoma on localization study results

Although the sensitivity of preoperative localization techniques is high for solitary parathyroid adenomas, negative imaging study results are inevitable. The weight and location of the parathyroid adenoma may contribute to the negative results. We aimed to study the impact of adenoma weight and ectopic location of the parathyroid adenoma on ultrasonography and sestamibi scan results. The patients were divided into two groups according to adenoma location. Group 1 consisted of 36 patients with ectopic location, and group 2 consisted of 149 patients with normal location. Parathyroid adenoma weight and the results of imaging studies were determined in all patients. Of 185 patients operated on for hyperparathyroidism, 36 (19.4%) had ectopic parathyroid glands. There was a positive correlation between adenoma weight and positive imaging studies, whereas ectopic location did not correlate with negative imaging study results. There was no significant difference between the ectopic adenoma ratio of patients with negative and positive imaging study results. The weight of the ectopic parathyroid adenoma was significantly lower in patients with negative imaging study results than in patients with positive imaging study results (p = 0.001). According to the analysis of variance, patients with higher-weight adenomas have positive imaging study results irrespective of ectopic location. For both normal and ectopic adenoma locations, adenoma weight was found only to be a factor that positively influences imaging study results.

Ultrasonography in detection of single and multiple abnormal parathyroid glands in primary hyperparathyroidism: comparison with radionuclide scintigraphy and surgery

BACKGROUND

Among the parathyroid imaging techniques, ultrasonography (USG) has the advantage of convenience, easy availability and low cost.

OBJECTIVE

To study the role of USG in localization (side and/or site) of abnormal parathyroid glands in primary hyperparathyroidism (PHPT) and to compare with radionuclide scintigraphy and the 'gold standard', surgery.

METHODS

Forty-six consecutive patients undergoing USG of the anterior neck for a diagnosis of PHPT in whom a nuclear scan (technetium-99m sestamibi and/or thallium-201/technetium-99m pertechnetate scintigraphy) was also performed, were studied. The results of imaging were independently interpreted and correlated with reference to surgical findings.

RESULTS

Forty-six patients had 52 abnormal parathyroid glands on surgical exploration and surgery was successful in all but one. Forty-one patients had a single adenoma, four had multigland disease and one had a paraganglioma. USG correctly localized the abnormal gland in 30 (73%) and scintigraphy was positive in 40 (98%) out of 41 patients with a single adenoma as confirmed on surgical exploration. Scintigraphy showed a positive concordant test in all 30 patients with a single abnormal gland detected on USG and picked up 10 out of 11 abnormal glands where USG was negative. The sensitivity and positive predictive value of USG for detecting a single abnormal gland was 73% and 100%, respectively, whereas the sensitivity and positive predictive value for scintigraphy was 98%. In patients with multigland disease, USG missed 3 (30%) out of 10 and scintigraphy missed 6 (60%) out of 10 abnormal parathyroid glands as confirmed on surgical exploration (P < 0.05). However, in two patients who had ectopic parathyroid gland, both the modalities localized the lesion in one (paraganglioma), whereas in the other neither test was helpful (left retro-esophageal).

CONCLUSION

USG is a convenient, affordable and useful modality to localize abnormal enlarged parathyroid glands in the majority of patients with PHPT. However, when USG is negative, scintigraphy is complementary to it.

A systematic review of the diagnosis and treatment of primary hyperparathyroidism from 1995 to 2003

OBJECTIVE

To systematically review the current preoperative diagnostic modalities, surgical treatments, and glandular pathologies associated with primary hyperparathyroidism.

STUDY DESIGN

A systematic literature review.

RESULTS

Of the 20,225 cases of primary hyperparathyroidism reported, solitary adenomas (SA), multiple gland hyperplasia disease (MGHD), double adenomas (DA), and parathyroid carcinomas (CAR) occurred in 88.90%, 5.74%, 4.14%, and 0.74% of cases respectively. Tc 99m -sestamibi and ultrasound were 88.44% and 78.55% sensitive, respectively, for SA, 44.46% and 34.86% for MGHD, and 29.95% and 16.20% for DA, respectively. Postoperative normocalcemia was achieved in 96.66%, 95.25%, and 97.69% of patients offered minimally invasive radio-guided parathyroidectomy (MIRP), unilateral, and bilateral neck exploration (BNE). Intraoperative PTH assays (IOPTH) were helpful in approximately 60% of bilateral neck exploration conversion (BNEC) surgeries.

CONCLUSION

The overall prevalence of multiple gland disease (MGD and DA) was lower than often suggested by conventional wisdom. Furthermore, preoperative imaging was less accurate than it is often perceived for accurately imaging MGD. MIRP and UNE were more successful in achieving normocalcemia than is typically quoted. IOPTH was a helpful but not "fool-proof" adjunct in parathyroid exploration surgery.

SIGNIFICANCE

These results support a greater role for the treatment of primary hyperparathyroidism using less invasive approaches. EMB rating: B-3.

Detection of multiple gland primary hyperparathyroidism in the era of minimally invasive parathyroidectomy

BACKGROUND

A focused surgical approach for primary hyperparathyroidism relies on the ability of preoperative imaging and intraoperative parathyroid hormone monitoring (IOPTH) to detect multiple gland disease (MGD). The study objective was to determine the best predictor for MGD.

METHODS

First time parathyroidectomy was performed on 233 patients with primary hyperparathyroidism who underwent preoperative sestamibi imaging, ultrasound, and IOPTH between December 1999 and January 2004.

RESULTS

Single gland disease (SGD) was found in 204 (88%) and MGD in 23 (10%) patients. Hyperparathyroidism persisted in 6 of 233 patients (2.6%). For patients with MGD, sestamibi imaging correctly predicted MGD in 2 of 23 (9%) patients, incorrectly showed SGD in 9 of 23 (39%), and was negative in 12 of 23 (52%). Ultrasound correctly predicted MGD in 6 of 23 (26%) patients, incorrectly predicted SGD in 6 of 23 (39%), and was negative in 8 of 23 (35%). Together sestamibi imaging and ultrasound predicted MGD in 7 of 23 (30%) patients, incorrectly predicted SGD in 7 of 23 (30%), was negative in 7 of 23 (30%), and was discordant in 10 of 23 (5%). IOPTH indicated MGD in 15 of 18 (83%) patients but falsely predicted cure after single gland excision in 3 of 18 (17%). The combination of sestamibi imaging, ultrasound, and IOPTH detected MGD in 16 of 18 (89%) patients.

CONCLUSION

Ultrasound was more sensitive for detecting MGD than sestamibi imaging. Ultrasound and sestamibi imaging together provided information warranting a bilateral approach in 70% of patients with MGD. IOPTH was the most sensitive for MGD, but combining all 3 tests was the best predictor, identifying the majority of patients with MGD.

Accuracy of surgeon-performed ultrasound in parathyroid localization

Ultrasound is one of the preferred modalities for localization of abnormal parathyroids. Accuracy of ultrasound is technician-dependent. This study was undertaken to determine the accuracy of surgeon-performed ultrasound (SPU) for the localization of parathyroid tumors in comparison to radiology-performed ultrasound (RPU) and nuclear scintigraphy (NS). In this series 74 consecutive patients with untreated primary hyperparathyroidism underwent SPU at the initial clinic visit; 21 of these patients did not undergo surgery and are excluded from the analysis. Of the 53 patients remaining, RPU was obtained in 26, and 52 patients underwent NS. Directed parathyroidectomy was performed with use of the intraoperative parathyroid hormone assay (IOPTH). In all, 46 patients had a single adenoma as indicated by IOPTH and final pathology. Two patients had double gland disease, and 5 patients had multi-gland hyperplasia. The sensitivity of SPU was 82% and the specificity was 90% in detecting the diseased glands on the correct side (right versus left). The sensitivity for RPU was 42% and the specificity was 92% (n = 26). The sensitivity of NS was 44% and the specificity was 98% (n = 52). In only one case did RPU or NS detect a gland not found by SPU. SPU can be done with accuracy comparable to other ultrasound series in the literature, and it may be superior to RPU or NS in some institutions. It is important for surgeons to be aware of local institutional expertise when relying on RPU and NS during preoperative evaluation prior to directed parathyroidectomy.

Localization of Parathyroid Adenomas By 99mTc-Sestamibi Scanning: Upper Neck Versus Lower Neck Lesions

OBJECTIVE

To assess the diagnostic properties of (99m)Tc-sestamibi scanning (dual-phase technique) in patients with primary hyperparathyroidism and to establish the overall efficacy of this imaging technique for localization of an adenoma.

METHODS

The medical records of all 131 patients who underwent parathyroid scanning in a tertiary care center between January 1997 and December 2002 were reviewed. The surgical findings were used as the "gold standard" for the diagnosis of parathyroid pathologic conditions.

RESULTS

Primary hyperparathyroidism was diagnosed in 87 of the 131 patients (66.4%); of these, 76 underwent surgical treatment. In 44 patients, sestamibi scanning was also done for conditions other than primary hyperparathyroidism. (99m)Tc-sestamibi scanning had a sensitivity of 79.1%, a specificity of 86.7%, a positive predictive value of 88.3%, a false-positive rate of 11.6%, and a false-negative rate of 23.3% for the diagnosis of parathyroid adenoma. Despite the apparent high sensitivity of this scanning technique, only 58.2% of the adenomas were found intra-operatively at the location predicted by the scan. Lesions in the upper neck area were missed more frequently by sestamibi scanning than were those in the lower neck area (13 of 32 versus 1 of 35, respectively) (P<0.05).

CONCLUSION

Preoperative localization of parathyroid adenomas with use of (99m)Tc-sestamibi scanning showed a limited capacity to reveal their precise location. Thus, such scans must be complemented with other studies, such as intraoperative ultrasonography and rapid parathyroid hormone assay, to ensure a successful excision if a limited surgical procedure is planned.

The cost-effectiveness of sestamibi scanning compared to bilateral neck exploration for the treatment of primary hyperparathyroidism

This article presents a cost-effectiveness analysis to determine whether preoperative imaging with Tc99m-sestamibi for detection and treatment of solitary adenomas associated with primary hyperparathyroidism is cost-effective compared with routine bilateral neck exploration.

Unilateral and bilateral surgery for parathyroid disease

The principles of successful parathyroid surgery, regardless of the approach, demand a clear understanding of the philosophy behind the surgical exploration. A systematic approach, founded in science and refined by experience, is necessary to achieve long-term, reproducible surgical success. This article discusses the underlying logic and the advantages and disadvantages of the two basic approaches to parathyroid pathology: unilateral and bilateral cervical exploration. The authors do not to advocate a particular technique;instead, they provide a conceptual framework to surgical parathyroid disease upon which more advanced discussion can be built.

Management of primary hyperthyroidism: toward minimal access surgery

Fifteen years ago, bilateral exploration of the neck was dogma in parathyroid surgery. Now, less invasive procedures can be used to target lesions identified by new tests such as dual-phase Sestamibi scanning or intraoperative documentation of parathyroid hormone (PTH) level changes after removal of a parathyroid gland. A hand-held gamma probe can be used for intraoperative detection of high-uptake lesions, and video-assisted endoscopic surgery has been used successfully. With these new techniques, surgical exploration can be confined to one side of the neck through smaller incisions associated with better cosmetic results. The operating time is reduced, and in some cases the procedure can be done under local anesthesia. The objective of this article is to describe recent changes in the management of parathyroid adenoma requiring surgery.

Intraoperative parathyroid hormone testing: what have we learned?

OBJECTIVES/HYPOTHESIS

The development of rapid, sensitive assays for measuring the intact parathyroid hormone (iPTH) molecule has the potential to allow the surgeon to determine the success of parathyroid surgery intraoperatively. The purpose of the study was to review our results in the context of currently held beliefs regarding the ability of the intraoperative iPTH to predict resolution of hyperparathyroidism.

STUDY DESIGN

Retrospective review.

METHODS

The study series is a retrospective review of 107 consecutive parathyroidectomies performed by a single surgeon. Patients with primary, secondary, and tertiary hyperparathyroidism were included.

RESULTS

The intraoperative assay allowed an overall success rate of 93.4% across all patient categories. The success rate in patients with primary hyperparathyroidism was 95.7%. Measuring the iPTH level at 10 versus 15 minutes after the removal of tissue did not significantly affect the predictive value of the test. A decrease of 50% in the iPTH level after the resection of hyperfunctioning tissue was prognostic of successful treatment of the hyperparathyroid state. By contrast, a postexcision iPTH level that was within the normal range was not always predictive of cure.

CONCLUSIONS

The intraoperative iPTH assay is particularly useful in the treatment of primary hyperparathyroidism. The assay eliminates the need for intraoperative frozen-section analysis in most cases and allows the surgeon to perform limited resections with confidence. This is especially true in complicated parathyroid surgeries, such as revision surgeries or those requiring concomitant thyroid surgery. The assay is also useful in secondary hyperparathyroidism, although it appears that the inability to identify small nonfunctional or hypofunctional supernumerary parathyroid glands means that long-term normocalcemia may not be assured.

Diagnosis of normocalcemic hyperparathyroidism by oral calcium loading test

We evaluated the oral calcium-loading test (OCLT) in diagnosing normocalcemic primary hyperparathyroidism. Calcium and PTH levels were measured before, 60, 120 and 180 min after oral 1 g of calcium gluconolactate administration in 102 consecutive females with high circulating PTH levels, and 25 controls. Patients were classified as follows: Group A, patients with a parathyroid adenoma identified by two imaging modalities. Sub-Group AO, hyperparathyroid patients [no.=13, mean age 59 yr (SD=10)] evaluated prior to parathyroidectomy. Sub-Group AH, non-operated hypercalcemic patients [no.=29, age 63 yr (SD=11)]. Sub-Group AN, normocalcemic non-operated women [no.=14, age 59 yr (SD=8)]. Group B, normocalcemic individuals [no.=46, age 58 yr (SD=11)] with negative parathyroid imaging. Group C, control patients [no.= 25, age 56 yr (SD=12)]. The concentrations of calcium and PTH overlapped in the normocalcemic groups during the OCLT. Product P, defined as circulating PTH nadir (pg/ml) x peak calcium concentration (mg/dl), better discriminated Sub-Group AN from Group B, AUC=0.98 (95% CI 0.95, 1.00) than did Ratio R, defined as relative PTH decline/relative calcium increment, AUC= 0.86 (95%CI 0.73, 0.99). Assuming normal threshold of Product P and Ratio R at 260 and 17 respectively, the combined parameters diagnose normocalcemic hyperparathyroid patients with 100% sensitivity and 87% specificity.

[Diagnostic value of parathyroid localization techniques in surgery for primary hyperparathyroidism]

OBJECTIVES

To determine the accuracy of imaging techniques for localization of nodular lesions of parathyroid glands.

MATERIAL AND METHODS

Seventy one patients were prospectively enrolled and underwent surgical examination for primary hyperparathyroidism. Ultrasonography (US), 201Tl/99mTc parathyroid subtraction scintigraphy and 99mTc MIBI scintigraphy were evaluated.

RESULTS

The sensitivity and specificity for combined 201Tl/99mTc parathyroid subtraction scintigraphy and US for parathyroid adenomas were 72.27% and 89.22% respectively. The combination of 99mTc MIBI scintigraphy and US resulted in improved specificity (93.67%) and positive predictive value (80.39%). The accuracy of the localizing studies was lower for patients with hyperplasia.

CONCLUSIONS

The combination of scintigraphy and US is the best approach for localization of nodules. In most cases, the two techniques are complementary.

Hyperparathyroidism associated with thyroid pathology

BACKGROUND

The pathological association between thyroid and parathyroid gland disease is here discussed. The multiphase analyzer has revealed a new type of subclinical primary hyperparathyroidism (HPP) and the role of surgery in these cases is not clear.

METHODS

This is a prospective study of all cases of thyroid disease in association with parathyroid disease treated surgically in our Institute from July 1999 to June 2001.

RESULTS

Of the 221 thyroidectomies carried out, 29 patients had an elevated preoperative serum level of parathyroid hormone (PTH). An ultrasonography examination was performed on all patients and a preoperative scanning with 99Tc-MIBI on 11 of 29 patients. We examined intraoperatively 19 cases of HPP (14 parathyroid adenoma, 5 hyperplasia). In 10 cases we observed a normal size of the parathyroid gland and we did not perform a parathyroidectomy.

CONCLUSIONS

All patients with elevated serum parathyroid hormone and serum calcium levels before thyroidectomy should be considered candidates also for surgery to the parathyroid glands. The pathological association between thyroid and parathyroid gland diseases is not rare. We must conduct an accurate neck exploration in all these cases.

Improving the yield of preoperative parathyroid localization: technetium Tc 99m-sestamibi imaging after thyroid suppression

BACKGROUND

Preoperative localization is essential for successful directed, minimally invasive or reoperative parathyroidectomy. Standard technetium Tc 99m-sestamibi imaging is the most sensitive modality for localization. We reviewed our experience with (99m)Tc-sestamibi imaging and specifically investigated the effect of thyroid suppression on repeat imaging of patients who had initially nonlocalizing scans.

METHODS

. The records of patients who underwent (99m)Tc-sestamibi imaging during evaluation for primary hyperparathyroidism were reviewed. A subset of patients with initially nonlocalizing scans underwent thyroid suppression with either thyroxin or liothyronine and then had their scans repeated.

RESULTS

Ninety-nine patients with primary hyperparathyroidism underwent (99m)Tc-sestamibi imaging followed by parathyroidectomy (initial operation, 78; reoperation, 21). Successful parathyroid localization was obtained on standard imaging in 67 patients. Fourteen of 32 patients who had nonlocalizing (99m)Tc-sestamibi imaging studies underwent an additional scan after thyroid suppression. In 10 of 14 patients (71%), repeat (99m)Tc-sestamibi imaging after thyroid suppression successfully localized abnormal parathyroid tissue.

CONCLUSIONS

Thyroid suppression may improve the yield of (99m)Tc-sestamibi imaging in patients with hyperparathyroidism who have an initially nonlocalizing study. This diagnostic strategy may be helpful in patients motivated to undergo a directed, minimally invasive operation, as well as in the evaluation of patients for reoperative parathyroidectomy.

Ultrasonography for preoperative localization of enlarged parathyroid glands in primary hyperparathyroidism: comparison with (99m)technetium sestamibi scintigraphy

OBJECTIVE

To determine the utility of ultrasonography for the preoperative localization of enlarged parathyroid glands in primary hyperparathyroidism, and to compare this method with (99m)technetium sestamibi scintigraphy.

DESIGN

The results of ultrasonography for localization of enlarged parathyroid glands were determined in 120 consecutive patients with primary hyperparathyroidism and compared with findings at surgery (n = 86) and with the results of (99m)technetium sestamibi scintigraphy (n = 99).

PATIENTS

All patients had biochemically documented primary hyperparathyroidism based on elevated serum calcium and 'intact' parathyroid hormone measured by immunoassay. Patients with prior parathyroid surgery or secondary hyperparathyroidism were excluded.

MEASUREMENTS

High-resolution ultrasonography was performed by a single observer. (99m)Technetium sestamibi scintigraphy was performed using early and delayed (2-h) views, and correlated with simultaneous thyroidal 123I uptake in most patients.

RESULTS

Ultrasonography detected putative enlarged parathyroid glands in 92 of 120 unselected patients (77%). It correctly predicted surgical findings in 64 of 86 patients undergoing surgery (74%), including 61 of 72 patients with solitary eutopic parathyroid adenomas (84%), but only two of eight patients with solitary ectopic adenomas, and only one of six patients with multigland parathyroid disease. Sestamibi scintigraphy was positive in 87 of 99 unselected patients (88%), a higher proportion than ultrasonography (P < 0.05), reflecting superior sensitivity for the detection of ectopic parathyroid adenomas. For 74 patients undergoing parathyroid surgery who underwent both imaging tests there was no statistically significant difference between ultrasonography and sestamibi scintigraphy in ability to correctly predict surgical findings (74%vs. 82%, respectively) or in positive predictive value (93%vs. 90%, respectively). However, sestamibi scintigraphy was clearly more sensitive for ectopic parathyroid adenomas, providing correct localization in 8/8 cases. When one test was negative, testing with the second method was usually positive, improving the likelihood of a positive result to 98% when both tests were employed.

CONCLUSIONS

Ultrasonography can be a sensitive and accurate method for preoperative localization of enlarged parathyroid glands in primary hyperparathyroidism, comparable in overall utility to sestamibi scintigraphy. These results suggest that a strategy of initial testing with one or the other method, followed by the alternate imaging test if the first test is negative, would provide correct parathyroid imaging in most patients without prior parathyroid surgery.

The efficacy of sestamibi parathyroid scintigraphy for directing surgical approaches based on modified interpretation criteria

PURPOSE

With the increasing use of targeted parathyroidectomy, the accuracy of sestamibi parathyroid scintigraphy (SPS) in determining the best surgical approach has become more clinically relevant than its sensitivity for detecting all abnormal glands. The reported accuracy of SPS does not represent the true efficacy of SPS for directing targeted parathyroidectomy, because many authors reported accuracy on the basis of abnormal glands. The authors assessed the efficacy of SPS based on modified interpretation criteria to determine specifically whether SPS influences the surgeon's choice of a targeted versus a conventional approach to parathyroidectomy.

METHODS

The authors reviewed the SPS studies (both dual-isotope subtraction and Tc-99m sestamibi dual-phase techniques) performed in 80 patients with primary hyperparathyroidism. All patients had surgery with histologic diagnoses, intraoperative PTH assays, and clinical follow-up.

RESULTS

Of 75 patients with solitary adenomas, 9 SPS studies were negative, equivocal, or showed two or more foci, and 66 studies showed a solitary focus on the correct side. Of these 66 studies, 63 showed a lesion in the correct quadrant (e.g., superior or inferior) and 3 predicted the correct side only but a wrong quadrant. The positive-predictive value of SPS was 100% for correctly identifying the side of the adenoma (thus correctly directing unilateral surgery) and 95.5% for correctly identifying the quadrant of the solitary adenoma.

CONCLUSION

The positive-predictive value of SPS for directing the surgical approach (but not for detecting individual lesions) that reveals a single focus is very high based on our modified interpretation criteria.

Parathyroid gland radionuclide scanning--methods and indications

The usefulness of preoperative radionuclide scanning of the parathyroid glands in patients with primary or secondary hyperparathyroidism was long controversial because available techniques were of limited diagnostic efficacy. Technetium-99m-labeled sestamibi (99Tc-sestamibi) is a new radiopharmaceutical agent easily detected by gamma cameras. The first parathyroid imaging studies done with 99Tc-sestamibi about 10 years ago used a double-phase technique to separate thyroid and parathyroid tissue. Although promising, this method was less than ideal, particularly in multiple gland primary hyperparathyroidism and in secondary hyperparathyroidism. For several years, we have been using subtraction between two images acquired simultaneously, one with 99Tc-sestamibi, which binds to thyroid and parathyroid tissue, and the other with 123-iodine, which binds only to thyroid tissue. The remarkable efficacy of this technique in both primary and secondary hyperparathyroidism invites a reappraisal of the place of radionuclide imaging as a preoperative localization procedure done to reduce the need for repeat surgery. The usefulness of this technique in selecting candidates for unilateral surgery among patients with primary hyperparathyroidism is discussed.

[Radioguided surgery for primary hyperparathyroidism. Experience in 75 cases]

STUDY AIM

To report feasibility and efficacy of radioguided mini invasive hyperparathyroidism surgery.

PATIENTS AND METHOD

From November 1998 to August 2000, 75 patients with primary hyperparathyroidism have been operated on by radioguided surgery within 90 to 180 minutes following i.v. injection of a diagnostic dose of MIBI and after parathyroid scanning with planar and oblique views. Exclusion criteria were thyroid pathology requiring surgery and suspicion of multiple endocrine neoplasia. A 20% step-up between the background noise and tissue uptake was the diagnostic threshold for parathyroid hyperfunctioning tissue.

RESULTS

A 20% step-up was observed in only 17% of cases overall; all cured, but two. Various angles of application of the probe can result in significant discrepancies of recorded uptake for the same spot. These results demonstrate a physiological step-up between the ipsilateral unaffected upper and lower quadrants of the neck (range: -17 to -8%), because of the proximity of supraortic vessels (upper neck-upper mediastinal gradient: -44 to -30%). Therefore, significant ratios are meaningful only between either the symmetrical left and right controlateral quadrants respectively, and not between the upper and the lower ipsilateral quadrants. Eleven per cent (8/75) of preoperative scannings were non-contributory, and probe detection was contributory in 3/8 cases only.

CONCLUSION

Benefit of the technique is limited in routine, but it can be helpful in redo cases if the offending gland is not located in close surroundings of tissues physiologically taking up the radiopharmaceutical (salivary glands, great vessels and heart).

A normal variant on Tl-201 and Tc-99m MIBI whole-body imaging: the superior right atrial wall (auricle) and superoanterior right ventricular wall are often seen as mediastinal lesions

PURPOSE

The authors have often observed on Tl-201 and Tc-99m sestamibi (MIBI) scans in patients with thyroid cancer a small focus of increased uptake in the right midparasternal region (focus A) or sometimes in the lower mid chest at the level of the lower sternum (focus B) just inferomedial to focus A. The objective of this study was to assess the frequency of this finding on Tl-201 MIBI studies, to assess the incidence of true pathologic lesions corresponding to these foci, and to identify their nature.

MATERIALS AND METHODS

One hundred ten whole body Tl-201 studies using 4 mCi (148 MBq) and 84 MIBI studies using 20 mCi (740 MBq: first-pass, planar, and SPECT images) were reviewed. The appearance of either focus A or focus B on three orthogonal SPECT images was correlated with an atlas of cross-sectional anatomy and computed tomography. If focus A was seen on the immediate static image (obtained at the end of the first-pass acquisition without moving the patient), this image was coregistered with a selected image from the first-pass study showing the superior vena cava and also with another selected image showing the ascending aorta.

RESULTS

Focus A was seen in 40% of Tl-201 scans and in 49% of MIBI scans, whereas focus B was seen in 20% of Tl-201 scans and 39% of MIBI scans. On correlation of the SPECT images with a cross-sectional anatomy atlas, focus A and focus B invariably corresponded to the superior portion of the right auricle and basal superoanterior right ventricular wall, respectively. These myocardial regions are prominent and sometimes appear as discrete foci because they are considerably thicker than other parts of the right atrial and right ventricular muscle, respectively, and because they are seen partly end-on in the anterior projection.

CONCLUSIONS

The superior portion of the right auricle and basal superoanterior right ventricular myocardium often appear as isolated foci on whole-body Tl-201 and MIBl scans. Neither focus should be interpreted as a metastatic lesion in patients with possible cancer or as an ectopic parathyroid adenoma in patients with hyperparathyroid disease.

Late parathyroid function after successful parathyroidectomy guided by intraoperative hormone assay (QPTH) compared with the standard bilateral neck exploration

BACKGROUND

Controversy continues between bilateral neck exploration and limited parathyroidectomy. One approach depends on gland size and histopathologic factors; the other approach limits excision to only hypersecreting glands. Both have excellent early operative success, but late recurrence rates with limited exploration are unknown.

METHODS

Three hundred twenty consecutive patients with primary hyperparathyroidism were followed 6 to 313 months after successful parathyroidectomy. One hundred seventy-six patients had bilateral neck exploration with excision of enlarged glands (group I); 144 patients had glands excised based on hyper-secretion (group II). Calcium and intact parathyroid hormone (iPTH) levels were measured yearly. Parathyroid gland hypersecretion was determined by elevated iPTH levels.

RESULTS

In group I, 1 gland was excised in 160 patients (91%); 19 of 176 patients (11%) had elevated iPTH levels. In group II, 139 patients (97%) had 1 gland excised; 19 of 144 patients (13%) had high iPTH levels. The number of patients with more than 1 gland excised in group I (9%) is 3 times higher than in group II (3%) (P <.05). There was no significant difference in the incidence of recurrent hyperfunctioning glands between the 2 different operative approaches (chi-squared test).

CONCLUSIONS

Late parathyroid gland function was comparable with both approaches. Multiple gland excision based on size alone may lead to excision of normal functioning glands.

Minimally invasive parathyroidectomy: 50 consecutive cases

OBJECTIVE

To determine the effectiveness and outcomes of minimally invasive parathyroidectomy.

DESIGN

Prospective, non-randomised, non-blinded trial.

SETTING

Affiliated university teaching hospitals of the Northern Clinical School, University of Sydney, New South Wales, May 1998 to October 1999.

PATIENTS

50 consecutive patients who underwent minimally invasive parathyroidectomy for primary hyperparathyroidism, and 150 consecutive patients undergoing open parathyroidectomy over the same period.

RESULTS

Minimally invasive parathyroidectomy was successfully completed and resulted in cure (normocalcaemia) in 42 of 50 patients (84%). Seven patients (14%) required conversion to an open procedure, all of which also resulted in normocalcaemia, giving an overall cure rate of 98%. One patient had persistent hyperparathyroidism after minimally invasive parathyroidectomy which was cured at subsequent open reoperation. Three patients had a temporary recurrent laryngeal nerve palsy. Open parathyroidectomy was successful in 147 of 150 patients (98%) at initial operation; one patient had a temporary recurrent laryngeal nerve palsy. Intraoperative measurement of parathyroid hormone levels by a quick technique in 23 of the patients (13 having minimally invasive and 10 open procedures) correctly identified the presence of multiple-gland disease.

CONCLUSION

Minimally invasive parathyroidectomy is a feasible procedure, although there are concerns about the complication rate.

Retrospective analysis of sequential changes in serum intact parathyroid hormone levels during conventional parathyroid exploration

BACKGROUND

The purpose of this study was to assess sequential changes in serum parathyroid hormone (PTH) levels during conventional parathyroidectomy.

METHODS

Sera were collected before and 10 minutes after resection of each parathyroid tumor from 112 consecutive patients and assayed postoperatively within 48 hours for PTH.

RESULTS

PTH reductions corroborated cures for 94 of 112 cases (84%), including 70 of 71 patients with solitary adenomas (SAs). However, there were 15 false positives (13%), in which PTH decreased more than 50% within 10 minutes of resection of 1 parathyroid tumor while additional parathyroid tumors remained in situ (1 of 71 SAs, 4 of 6 double adenomas, 7 of 15 primary hyperplasias, and 3 of 17 tertiary hyperplasias). There were 3 false negatives (3%), with PTH unchanged, even though postoperative PTH and calcium values confirmed cure (1 SA, 1 primary hyperplasia, and 1 tertiary hyperplasia). There were only 2 of 112 failed explorations (1.8%), which would not have been avoided by PTH monitoring because both subsequently were found to have mediastinal parathyroid adenomas.

CONCLUSIONS

We conclude that intraoperative PTH changes corroborated outcome in SA but may under-estimate the extent of resection required in parathyroid hyperplasia.