An Ectopic Mediastinal Parathyroid Adenoma Accurately Located by a Single-Day Imaging Protocol of Tc-99m Pertechnetate–MIBI Subtraction Scintigraphy and MIBI-SPECT–Computed Tomographic Image Fusion

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Abstract
Because ectopic parathyroid adenoma (PA) is a frequent cause of failed initial surgery, an imaging approach with accurate preoperative localization is recommended by some authors in patients with primary hyperparathyroidism (HPT). The authors describe a 52-year-old woman in whom primary HPT was diagnosed incidentally during a screening program for osteoporosis. The peculiarity of this case is that the patient was examined before operation in a single-day multimodal imaging protocol based on the combination of high-resolution cervical ultrasound, planar Tc-99m pertechnetate–MIBI scans, and an MIBI-SPECT–computed tomographic (CT) image fusion study. An ectopic PA was accurately located in the upper middle mediastinum, close to the lower margin of the sternal notch. Guided by the MIBI-SPECT–CT fusion images, the surgeon performed a limited median sternotomy and easily removed the PA that was revealed before operation. To confirm the completeness of resection, a bilateral neck exploration was performed through the same incision, with identification of three normally sized parathyroid glands. Our experience suggests the utility of multimodality imaging procedures for the accurate preoperative localization of PAs, particularly when they are present in ectopic mediastinal locations. Such procedures, including the MIBI-SPECT–CT image fusion study, can be performed in a single day.