The EANM practice guidelines for parathyroid imaging.

INTRODUCTION: Nuclear medicine parathyroid imaging is important in the identification of hyperfunctioning parathyroid glands in primary hyperparathyroidism (pHPT), but it may be also valuable before surgical treatment in secondary hyperparathyroidism (sHPT). Parathyroid radionuclide imaging with scintigraphy or positron emission tomography (PET) is a highly sensitive procedure for the assessment of the presence and number of hyperfunctioning parathyroid glands, located either at typical sites or ectopically. The treatment of pHPT is mostly directed toward minimally invasive parathyroidectomy, especially in cases with a single adenoma. In experienced hands, successful surgery depends mainly on the exact preoperative localization of one or more hyperfunctioning parathyroid adenomas. Failure to preoperatively identify the hyperfunctioning parathyroid gland challenges minimally invasive parathyroidectomy and might require bilateral open neck exploration. METHODS: Over a decade has now passed since the European Association of Nuclear Medicine (EANM) issued the first edition of the guideline on parathyroid imaging, and a number of new insights and techniques have been developed since. The aim of the present document is to provide state-of-the-art guidelines for nuclear medicine physicians performing parathyroid scintigraphy, single-photon emission computed tomography/computed tomography (SPECT/CT), positron emission tomography/computed tomography (PET/CT), and positron emission tomography/magnetic resonance imaging (PET/MRI) in patients with pHPT, as well as in those with sHPT. CONCLUSION: These guidelines are written and authorized by the EANM to promote optimal parathyroid imaging. They will assist nuclear medicine physicians in the detection and correct localization of hyperfunctioning parathyroid lesions.

Molecular imaging of thyroid and parathyroid diseases.

INTRODUCTION: Molecular imaging of thyroid and parathyroid diseases has changed in recent years due to the introduction of new radiopharmaceuticals and new imaging techniques. Accordingly, we provided an clinicians-oriented overview of such techniques and their indications. AREAS COVERED: A review of the literature was performed in the PubMed, Web of Science, and Scopus without time or language restrictions through the use of one or more fitting search criteria and terms as well as through screening of references in relevant selected papers. Literature up to and including December 2023 was included. Screening of titles/abstracts and removal of duplicates was performed and the full texts of the remaining potentially relevant articles were retrieved and reviewed. EXPERT OPINION: Thyroid and parathyroid scintigraphy remains integral in patients with thyrotoxicosis, thyroid nodules, differentiated thyroid cancer and, respectively, hyperparathyroidism. In the last years positron-emission tomography with different tracers emerged as a more accurate alternative in evaluating indeterminate thyroid nodules [18F-fluorodeoxyglucose (FDG)], differentiated thyroid cancer [124I-iodide, 18F-tetrafluoroborate, 18F-FDG] and hyperparathyroidism [18F-fluorocholine]. Other PET tracers are useful in evaluating relapsing/advanced forms of medullary thyroid cancer (18F-FDOPA) and selecting patients with advanced follicular and medullary thyroid cancers for theranostic treatments (68Ga/177Ga-somatostatin analogues).

Incidental finding of [99mTc]Tc-MIBI uptake in a post-radiotherapy breast without recurrence of cancer.

The oncophilic nature of [99mTc]Tc-MIBI makes this radiopharmaceutical useful in cancer diagnostics, with particular emphasis on breast cancer. Increased uptake of [99mTc]Tc-MIBI in tests performed for non-oncological indications always raises the suspicion of its neoplasmatic character and requires further clinical diagnostics, which is especially justified in patients with a previous history of cancer. However, the presented case illustrates that focally increased uptake of [99mTc]Tc-MIBI is not always associated with the presence of cancer cells and may result from post-therapeutic changes.

Diagnostic Value of Choline PET in the Preoperative Localization of Hyperfunctioning Parathyroid Gland(s): A Comprehensive Overview.

Hyperparathyroidism is a metabolic disorder characterized by the excessive production of the parathyroid hormone. The diagnosis is based on clinical and laboratory data. In most cases the only treatment is surgery and a correct preoperatory localization of the hyperfunctioning parathyroid gland(s) is essential. Currently, ultrasonography combined with [99mTc]Tc-MIBI parathyroid scintigraphy, optionally associated with single photon emission computed tomography/computed tomography (SPECT/CT), represent the standard preoperative imaging. In recent years, a number of studies have evaluated the potential role of choline positron emission tomography (PET) in hyperparathyroidism with promising results. Most of the recent evidence underlined its higher sensitivity and diagnostic accuracy in the localization of hyperfunctioning parathyroid glands. Choline PET has a higher spatial resolution that is useful for the detection of smaller parathyroid glands and it also has shorter examination times and favorable radiation exposure. These are just a few of the aspects that support it to overcome traditional imaging. Moreover, from the preliminary data, the choline uptake mechanism seems to also have an impact on its better performance. For these reasons, if first used as second level imaging in patients with negative or inconclusive traditional imaging results, several authors have supported its use as a first line investigation. This comprehensive overview aims to provide an accurate description of the preliminary results available in the literature about the use of choline PET/CT in hyperparathyroidism and to compare these results with the performance of traditional imaging methods.

The efficacy of low and high dose (99m)Tc-MIBI protocols for intraoperative identification of hyperplastic parathyroid glands in secondary hyperparathyroidism.

OBJECTIVE: The aim of this study was to compare the efficacy of low- and high-dose (99m)Tc-MIBI protocols for intraoperative identification of hyperplastic parathyroid glands via gamma probe in secondary hyperparathyroidism. MATERIAL AND METHODS: This retrospective study was conducted using a prospective database of 59 patients who had undergone radioguided subtotal parathyroidectomy between 2004-2012. The patients were studied in 2 groups. Group 1 (n=31) received 37 MBq (99m)Tc-MIBI intravenously in the surgical room approximately 10 min before the beginning of the intervention and surgery was performed under gamma probe guidance. Group 2 (n=28) received 555 MBq (99m)Tc- MIBI intravenously 2h before surgery, which was also performed under gamma probe guidance. Intraoperative gamma probe findings, laboratory findings, and histopathological findings were evaluated together. RESULTS: Using acceptance of the histopathological findings as gold standard, sensitivity and specificity of intraoperative gamma probe for identifying hyperplastic parathyroid glands was 98% and 100%, respectively, in both groups. CONCLUSIONS: In the light of these findings, it is concluded that the low-dose (99m)Tc-MIBI protocol might be preferable for intraoperative identification of hyperplastic parathyroid glands in secondary hyperparathyroidism patients because it was observed to be as effective as the high-dose (99m)Tc-MIBI protocol. Furthermore, the low-dose protocol does not have the disadvantages that are associated with the high-dose protocol.

Myocardial Perfusion Imaging in Myocardial Infarction Using 99mTc-MIBI : A New Myocardial Imaging Agent

Technetium-99m methoxyisobutylisonitrile(99m-Tc MIBI), a new myocardial imaging agent, was used in myocardial perfusion scan in 23 patients who had been diagnosed as myocardial infarction to assess its usefulness in elvaluation of coronary artery disease. All patients undertook left ventriculography (LVG) and coronary arteriography (CAG). Gated blood pool scan, plannar scintigraphy and SPECT were also done using 99m-Tc MIBI. After then SPECT image was reconstructed to short axis view of the heart at the level of the base, mid and apex. The data from these studies were compared with the results of EKG, LVG and CAG. Diagnostic sensitivity of myocardial scan using 99m-Tc MIBI was 91.3%. In localization of infarction site and evaluation of its extent, myocardial scan was superior to EKG. CAG revealed significant stenosis at the arteries supplying the area in which the scan showed perfusion defect. In detecting abnormal wall motion, the sensitivity and the specificity were 81.9% and 93.7% respectively. Perfusion defect were found in 75%, 82.5%, and 100% of hypokinetic, akinetic, and dyskinetic segments, respectively. Myocardial perfusion scan using 99m-Tc MIBI was an useful noninvasive test in localizing the site and the extent of infarct and detecting the abnormal left ventricular wall motion.