Endocrine Abstracts

Primary hyperparathyroidism is a common disorder which is curable by surgery. Exact localisation of parathyroid adenoma is essential for minimal invasive approach. The gold standard is sestamibi SPECT/CT nowadays - but fails in approximately 10% cases. In last 3 years some case report with 18F-choline PET/CT were published. We describe two cases with SPECT/CT invisible parathyroid adenoma.

First case was 36y/o woman, with osteopenia diagnosed after pregnancy (was attributed to LMWH treatment in pregnancy) and no relevant health problems. Mild hypercalcemia (2.7 mmol/l) was found in 2014 in context with vitamine D deficiency and patient was referred to our department. Primary hyperparathyroidism was clearly stated (serum calcium 2.9 mmol/l; PTH 130 ng/l; 25-OH-D vitamine 69 nmol/l), bone turnover was also slightly elevated. According to age, osteopenia and planned pregnancy we decided for surgery, but ultrasonography and sestamibi SPECT/CT was without any parathyroid adenoma. Patient did not agreed with surgical revision of all four glands and we choosed conservative approach. In 2015, hypercalciuria was appeared, therefore next SPECT/CT and ultrasonography was performed, with still negative results. In 2016 we used PET/MRI with 18F-choline for the first time in our hospital – upper left parathyroid adenoma was found (9×6 mm, SUVmax 5.8). Patient was referred to surgery and histologic examination reveals parathyroid adenoma and patient went normocalcemic, normocalciuric and with normal PTH level, with continuing D vitamine treatment due to osteopenia. No hungry bone syndrome was presented.

Second case was 59 y/o man, with primary hyperparathyroidism treated for 3 years by cinacalcet, with twice negative sestamibi SPECT/CT, repeatedly negative ultrasonography. During the treatment was slightly hypercalcemic (2.6 mmol/l), normocalciuric, with non-progressing osteopenia. PET/MRI revealed 8mm left bottom parathyroid adenoma and patient was referred for surgical resection, planned for March 2017.

Despite our limited experiences, 18F-choline PET seems to be a promising diagnostic option. Using MRI instead of CT has some advantages – radiation load, no risk of iodine contrast allergy and slightly better resolution in neck region.