Introduction: Minimally invasive surgical treatment of primary hyperparathyroidism (PHPT) requires optimal preoperative localisation imaging. Parathyroid four-dimensional CT (4D-CT) has been reported to provide greater sensitivity than MIBI-SPECT/CT in localizing parathyroid adenomas. We analysed the additional value of 4D-CT in our cohort of PHPT patients.
Materials and methods: Patients who attended our parathyroid clinic between February 2016 and April 2017, with biochemically unequivocal PHPT and meeting criteria for surgery were included. All patients underwent Ultrasound and MIBI-SPECT/CT. Patients with inconclusive imaging underwent additional 4D-CT.
Results: Fifty-two patients (77% female) with a mean age of 66.2±14.9 years were included. To date 17/23 patients with inconclusive imaging results underwent additional 4D-CT. Surgical correlation so far has been positive in 4/4 positive 4D-CTs. An intrathyroidal parathyroid adenoma was found in 1 patient with a negative 4D-CT.
|Positive||29/52 (55.8%)||29/52 (55.8%)||13/17 (76.4%)|
|Negative||20/52 (38.5%)||22/52 (42.3%)||3/17 (17.6%)|
|Equivocal||3/52 (5.7%)||1/52 (1.9%)||1/17 (5.9%)|
|MIBI-SPECT/CT||4D-CT vs 4D-CT adjusted protocol||Annual UK Background Exposure|
|Calculated exposure||8.5 mSv||18 mSv vs 12 mSv||2.7 mSv|
Conclusions and discussion: We have been able to radiologically localize a parathyroid adenoma in a majority of our PHPT patients with inconclusive imaging. Surgical correlation is ongoing, but results so far are promising. 4D-CT incurs radiation exposure, particularly to the thyroid and therefore should be used cautiously, especially in younger patients. Population risk for developing any cancer is 1/1000 after 4D-CT, 1/1700 after 4D-CT adjusted protocol and 1/2400 after MIBI-SPECT/CT. Lifetime attributable risk for thyroid cancer after 4D-CT is 1/100,000 in patients >60 years vs 1/2600 in patients of 30 years. MIBI-SPECT/CT is five times more expensive than 4D-CT (£630 vs £125). Currently, first line imaging consists of Ultrasound and MIBI-SPECT/CT. 4D-CT has additional value in PHPT patients with negative conventional imaging. We suggest that 4D-CT should be considered as first line imaging in patients over 60 years presenting with PHPT. Optimising the sensitivity of parathyroid imaging should result in more patients having minimally invasive surgery.
06 Nov 2017 - 08 Nov 2017