Role of 18Fluorocholine Positron Emission Tomography/Computed Tomography in the Localization of Culprit Lesions in Patients of Persistent/Recurrent Primary Hyperparathyroidism: A Prospective Study in COVID Times.

Introduction: Recurrent/persistent primary hyperparathyroidism in patients who have undergone previous parathyroidectomy is a challenging condition. Imaging is important for localizing the parathyroid adenoma for re-exploration and 18F-Fluorocholine (18F-FCH) positron emission tomography/computed tomography (PET/CT) seems ideal for this purpose. Aim: This prospective study attempted to ascertain the utility of 18F-FCH PET/CT as an investigation in preoperative localization of abnormal parathyroid tissue in recurrent/persistent primary hyperparathyroidism while comparing it with 99mTc-Sestamibi dual-phase scintigraphy with early single-photon emission CT (SPECT)/CT and neck ultrasonography (USG). Methods: Twenty patients with biochemical features of recurrent/persistent primary hyperparathyroidism were enrolled into this study. They underwent neck USG, 99mTc-Sestamibi dual-phase scintigraphy with early SPECT/CT and 18F-FCH PET/CT for localization of parathyroid lesions. Six patients underwent surgical resection of the detected lesions, 3 were awaiting surgery, and 11 were managed conservatively. One patient died due to COVID. Results: The calculated positive predictive values on a per-lesion basis of neck USG, 99mTc-sestamibi scintigraphy and early SPECT/CT and 18F-FCH PET/CT in the cohort of the 5 operated patients were 75% (3/4), 71.4% (5/7), and 71.4% (5/7), respectively. On a per-patient basis, the lesion detection rate was 100% for 99mTc-sestamibi scan and FCH PET (5/5) and 80% on neck USG (4/5). Conclusion: 18F-FCH PET/CT is a highly accurate imaging modality for the detection of parathyroid lesions in patients with recurrent/persistent primary hyperparathyroidism.

Comparison of Neck Ultrasonography, Dual Phase 99mTc-Sestamibi with early SPECT-CT & 18F-Fluorocholine PET-CT as First Line Imaging in Patients with Primary Hyperparathyroidism.

Introduction: Successful surgical treatment for primary hyperparathyroidism requires accurate localization of abnormal parathyroid tissue in terms of location and number. Imaging is important for localizing the parathyroid adenoma, and there has been significant interest in 18F-fluorocholine (FCH) positron emission tomography/computed tomography (PET/CT) for this purpose. Aim: This study attempted to ascertain the utility of 18F-FCH PET/CT as a first-line investigation in preoperative localization of abnormal parathyroid tissue in primary hyperparathyroidism, in comparison with 99mTc-sestamibi dual-phase scintigraphy with early single-photon emission computed tomography (SPECT)/CT and neck ultrasonography. Materials and Methods: Fifty-five patients with biochemical features of primary hyperparathyroidism were enrolled in this study. They underwent neck ultrasonography, 99mTc-sestamibi dual-phase scintigraphy with early SPECT/CT, and 18F-FCH PET/CT for localization of parathyroid lesions. Thirty-three patients underwent surgical resection of the detected lesions. For two patients, clinical and biochemical follow-up was used as a gold standard. Results: A total of 40 lesions were resected in the 33 patients who underwent surgery. A further two lesions were localized in two patients with clinical and biochemical follow-up as the gold standard. Of these 42 lesions, 41 were detected in preoperative imaging and 1 lesion was noted intraoperatively and resected. 41/42 lesions were detected by 18F-FCH PET/CT (detection rate: 97.6%), 33/42 by 99mTc-sestamibi dual-phase scintigraphy with early SPECT/CT (detection rate: 78.5%), and 30/42 by neck ultrasonography (detection rate: 71.4%). Conclusion: Detection rates on 18F-FCH PET/CT were superior to both 99mTc-sestamibi dual-phase scintigraphy with early SPECT/CT and neck ultrasonography in preoperative localization of parathyroid lesions in patients with primary hyperparathyroidism.

Lincoln Sign in a Case of Primary Hyperparathyroidism on 18 F-Fluorocholine PET/CT.

ABSTRACT: Lincoln sign or black beard sign is one of the signs that have been classically described on bone scintigraphy in monostotic Paget disease, when mandible is involved. Extensive involvement of the mandible causes increased radiotracer uptake from one mandibular condyle to the other, resembling a black beard. We present the case of a 14-year-old girl with primary hyperparathyroidism who underwent an 18 F-fluorocholine PE/CT to locate the parathyroid adenoma. MIP image of the PET/CT incidentally showed black beard sign due to increased radiotracer uptake in the mandible.

Imaging characteristics of phosphaturic mesenchymal tumors.

BACKGROUND: Tumor-induced osteomalacia (TIO) is a rare paraneoplastic syndrome associated with phosphaturic mesenchymal tumors (PMTs). Localization of the causative tumor in these cases is an arduous task since the culprit lesions are usually small, slow-growing, and can be located almost anywhere from head to toe. PURPOSE: To describe the morphological characteristics of histologically proven PMTs on various radiological modalities. MATERIAL AND METHODS: After institutional ethical approval, this retrospective study analyzed 20 cases with a histopathological evidence of PMT. Various imaging characteristics of the tumors on available computed tomography (CT) and magnetic resonance imaging (MRI) scans were evaluated. Descriptive statistical analyses were conducted. RESULTS: The tumors were located in diverse locations: lower extremities (n = 10); head and neck (n = 5); vertebral column (n = 3); pelvis (n = 1); and upper extremities (n = 1). Bone lesions seen on CT had variable morphology: sclerotic (n = 3/8, 37.5%); lytic (n = 3/8, 37.5%), and both lytic and sclerotic (n = 2/8, 25%) with presence of narrow zone of transition in all cases (n = 8/8) and amorphous internal matrix calcifications in 25% of cases (n = 2/8). Of the tumors, 68.4% (n = 13/19) were hypointense on T1 and all of them showed hyperintense signal on T2-weighted and STIR images (n = 19/19) and contrast enhancement (n = 16/16). Of the tumors, 66.7% (n = 6/9) showed restricted diffusion. DOTANOC PET/CT showed tumor uptake in all cases (n = 8/8). CONCLUSION: PMTs may have variable and non-specific tumor appearances on various imaging modalities. However, in an appropriate clinical scenario and a background of suggestive biochemical work-up, the radiologist should keep a high index of suspicion.

Impact of Fluoro-Choline PET/CT in Reduction in Failed Parathyroid Localization in Primary Hyperparathyroidism.

INTRODUCTION: Accurate localization of the pathological parathyroid gland is a prerequisite for minimally invasive surgical management of hyperparathyroidism (HPT). Poor imaging or discordance in odd situations like ectopic adenomas, parathyroid hyperplasia, syndromic HPT results in localization dilemma thus causing failed parathyroidectomy. We studied the impact of Fluoro-Choline (FCH) PET/CT imaging in reduction in localization failure of parathyroid adenoma. MATERIALS AND METHODS: We did a retrospective observational study (2018-2021) of HPT among which 97 patients underwent focused parathyroidectomy (FP). All patients had undergone ultrasound imaging and 99mTc-sestaMIBI scan with early SPECT/CT (MIBI). When this preliminary imaging was doubtful or negative or multiple lesions were expected, FCH PET/CT was performed. We compared the localization accuracy of MIBI scan and FCH PET/CT with surgical outcomes as reference standard. RESULTS: MIBI scan showed overall lesion detection rate (LDR) of 88.65% in localization of pathological parathyroid gland in 97 patients. The addition of FCH PET/CT improved the overall lesion detection to 97.9%. The overall possible localization failure was reduced from 11.34 to 2.06% with the addition of FCH PET/CT (p < 0.05). Out of 97 patients of FP, 87 patients showed features of parathyroid adenoma. Single hyperplastic gland was seen in 7 patients, lipoadenoma was seen in 1 patient and 1 patient had features suggestive of parathyroiditis on histopathology. FCH PET/CT was a useful adjunct and showed significant reduction in localization failure of parathyroid adenoma.