Review articleNuclear medicine imaging of the parathyroid
Section snippets
Parathyroid anatomy, physiology, and pathology
Hyperparathyroidism is relatively common disorder of calcium balance that is being increasing recognized, in part because of the use of automated chemistry studies that include serum calcium estimation. The incidence is approximately 100 to 200 per 100,000, with women, generally postmenopausal, being affected two to three times more commonly than men [1]. Hyperparathyroidism may present asymptotically following routine biochemistry analysis or with a myriad of symptoms including renal stones,
Early noninvasive preoperative evaluation
The standard noninvasive imaging procedures for localizing parathyroid adenomas and hyperplasia include high-resolution ultrasound, parathyroid scintigraphy, CT, and MRI. Early experience with multimodal preoperative imaging was not encouraging, as the results of Krubsack's [6] prospective preoperative evaluation of 100 patients showed. This study employed ultrasound, MRI, CT, and Thallium-201 (201Tl)/pertechnetate subtraction imaging. The overall sensitivity varied from 55% to 73% and improved
History
The earliest attempts at radionuclide parathyroid imaging used imaging techniques such as 57Cobalt-vitamin B12, 75Selenium methionine, and 131Cesium scanning [13], [14]. The use of 201Tl chloride gave nuclear parathyroid imaging some credence. 201Tl, however, is taken up by both the thyroid and abnormal parathyroid glands, and an image of only the thyroid activity was desired. This image was achieved by the addition of an injection of 99mTc- pertechnetate, which is a standard agent for nuclear
Sestamibi parathyroid imaging
The Tc-labeled myocardial perfusion agent, 99mTc hexakis 2-methoxy-isobutyl isonitrile (sestamibi) was introduced by DuPont Merck Pharmaceuticals (Billerica, Massachusetts) to replace and improve the image quality of 201Tl myocardial perfusion imaging. Because of the higher, more ideal photon energy and shorter half-life, which reduced patient radiation exposure, greater injected activity could be administered, significantly improving in myocardial image quality and accuracy for coronary artery
Using low-dose 99mTechnitiium pertechnetate
A number of studies show improved accuracy of sestamibi parathyroid imaging with the addition of some form of thyroid subtraction, either with a low-dose 99mTc thyroid image or preferably with 123Iodine [35], [36], [37]. To obtain a computer subtraction parathyroid image, the nuclear data must be acquired digitally. The subtraction studies using low-dose 99mTc are performed by injecting 1 mCi of 99mTc intravenously, waiting 15 minutes, then obtaining an anterior pinhole image of the thyroid.
Sestamibi scan accuracy
A number of studies have demonstrated the increased performance of sestamibi over the 201Tl/pertechnetate imaging [48], [49]. This better performance translates into both increased accuracy and the detection of smaller glands. Better performance is also realized with the shift from dual-phase sestamibi-alone imaging to dual-isotope (pertechnetate or 123Iodine/sestamibi) protocols, particularly if these include SPECT along with the subtraction imaging [50]. Overall accuracy figures are somewhat
Sestamibi limitations
In a number of situations the sestamibi scan may not perform adequately, giving false-negative results, particularly for small parathyroid glands (usually less than 100 mg). False-negative results are also common in patients with parathyroid hyperplasia, in whom sestamibi uptake has been documented to be lower than in patients with adenomatous disease [53]. False-negative sestamibi studies are also likely when there is a high proportion of clear cells and in the presence of the multidrug
Other nuclear parathyroid imaging
There have been a limited number of reports of the use of positron emission tomography (PET) scanning with F-18 FDG (fluoro-deoxy-glucose) for parathyroid disease. The most extensive study compared dual-phase sestamibi SPECT with FDG PET and found that SPECT had a significantly better sensitivity (86% versus 43%) but a reduced specificity (90% versus 76%) [60]. Given that sensitivity generally improves by 20% to 40% with dual-isotope subtraction sestamibi SPECT compared with the dual-phase
References (63)
- et al.
Primary hyperparathyroidism, a surgical perspective
Endocrinol Metab Clin N Am
(1989) - et al.
Sestamibi parathyroid imaging
Semin Nucl Med
(1995) - et al.
Initial failure of surgical exploration in patients with primary hyperparathyroidism
Am J Surg
(1990) Parathyroid imaging: its current status and future role
Semin Nucl Med
(1987)- et al.
Technetium thallium scintiscanning for localization of parathyroid adenomas and hyperplasia, a reappraisal
Am J Surg
(1987) - et al.
Technetium 99m sestamibi scan is the useful procedure to locate parathyroid adenomas before surgery
Am J Surg
(1996) - et al.
Intraoperative localization of parathyroid glands with gamma counter probe in primary hyperparathyroidism: a prospective study
J Am Coll Surg
(2002) - et al.
Sestamibi versus thallium subtraction scintigraphy in parathyroid localization: a prospective comparative study in patients with predominantly mild primary hyperparathyroidism
Surgery
(1997) - et al.
Technetium 99m-MIBI-SPECT: a highly sensitive diagnostic tool for localization of parathyroid adenomas
Surgery
(2000) - et al.
Multiglandular disease in seemingly sporadic primary hyperparathyroidism revisited: where are we in the early 1990s? A plea against unilateral parathyroid exploration
Surgery
(1992)