247 Single-Photon Emission Computed Tomography (SPECT) In Predicting Localisation of Parathyroid Adenomas: A Closed-Loop Prospective Study

Aim to measure the sensitivity of SPECT in localising parathyroid adenomas particularly whilst attempting minimally invasive parathyroidectomy. Method 2-cycles prospective study correlating SPECT and operative findings was conducted. All patients underwent ultrasound and SPECT, those with concordant findings on both modalities underwent minimally invasive parathyroidectomy, whilst patients with discordant findings on both modalities had central neck exploration. Following operative findings, recommendations of changing the SPECT reporting method such as surgically relevant structures adjacent to the lesion, such as the thyroid, were implemented. Following which, a second prospective study assessed the outcome of change. Results In the first cycle, 20 patients underwent partial parathyroidectomy, either by open (n = 13), or minimally invasive (n = 7) approach. SPECT sensitivity was 85% (n = 17) in identifying the adenoma. Out of all histologically confirmed adenomas, SPECT identified all adenomas (n = 17) on the correct side and 41% (n = 7) on the correct level (superior vs. inferior parathyroid). In the second cycle following recommendation, 14 patients had surgery, 9 as minimally invasive and 5 as open approach. SPECT sensitivity was 79% (n = 11) for adenoma identification. Of all confirmed adenomas, SPECT identifying adenomas at the correct side increased to 91% (n = 10) and correct level to 91% (n = 10). Conclusions SPECT alone is not yet regarded as gold standard in parathyroid adenoma localisation. The study has demonstrated that feedback to the radiologist of the operative findings may enhance its usefulness, particularly in attempting to proceed with a minimally invasive parathyroidectomy.

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.

Individualised Timing of Radio-Guided Parathyroidectomy Using Multi-Phase SPECT/CT Increases In Vivo Sensitivity and Accuracy and Reduces Operating Time: A Randomised Clinical Trial

Background: Minimally invasive parathyroidectomy is the preferred treatment for primary hyperparathyroidism. Despite relatively accurate preoperative information, minimally invasive parathyroidectomy can be challenging, especially in the case of small and ectopic adenomas. Radio guidance aids in both in vivo identification and ex vivo confirmation of adenoma. In vivo accuracy is currently not satisfactory. The present study evaluated whether a beneficial effect (increased sensitivity, specificity, accuracy) is obtained with individualised timing of minimally invasive radio-guided parathyroidectomy (MIRGP) using preoperative multi-phase 99mTc-MIBI single photon emission computed tomography (SPECT)/computed tomography (CT). Methods: This randomised clinical trial was conducted from May 2016 to January 2020 in a tertiary referral hospital. Adult patients with primary hyperparathyroidism sent for 99mTc-MIBI SPECT/CT were included consecutively and randomly assigned to conventional (dual-phase) SPECT/CT and conventional MIRGP (group I) or multi-phase SPECT/CT and individualised MIRGP (group II). One hundred of 106 eligible patients were included, and 83 patients underwent complete intervention. Results: A total of 47 patients in group I and 35 patients in group II were analysed. Group II had a shorter operating time (p = 0.003). The in vivo sensitivity and accuracy of radio guidance was 85.1% in group I and 100% in group II (p = 0.046), and 90.4% in group I and 100% in group II (p = 0.021), respectively. We found no difference in the in vivo specificity and ex vivo parameters between groups. Conclusion: Individualised timing increased the in vivo sensitivity and accuracy of radio guidance and reduced operating time, as some parathyroid adenomas rapidly wash out the radionuclide.