CT may be best modality to localize abnormal thyroid glands

4D CT provided sufficient presurgical accuracy in the localization of abnormal parathyroid glands in patients with primary hyperthyroidism, according to a study published in the October issue of Radiology. The findings suggest that CT might replace ultrasound and SPECT in this application, which could decrease healthcare costs by eliminating duplicate exams.

The treatment of hyperthyroidism has shifted toward less invasive surgical techniques. Unilateral or targeted surgery, however, requires presurgical localization. Ultrasound and technetium 99m sestamibi, with sensitivities of 55 percent and 62 percent, respectively, have been used for this purpose. Although sensitivity rises to 73 percent when the exams are paired, spatial resolution remains problematic in some cases. Researchers have noted that this safer, less costly surgical approach requires accurate localization of the lesion.

George G. Hunter, MD, PhD, from the department of neuroradiology at Massachusetts General Hospital in Boston, and colleagues devised a retrospective study to investigate the value of 4D CT to identify patients with newly diagnosed primary hyperthyroidism who had only one parathyroid lesion located in the neck. Specifically, the researchers sought to determine if the technique localized the abnormal glands to the correct side and quadrant. Surgical findings served as the standard of reference.

The study population included 143 patients with hyperparathyroidism who underwent CT between August 2004 and January 2007 and were candidates for unilateral or targeted parathyroidectomy.

The researchers mined the EMR to record the side and quadrant of the abnormal glands based on the CT report. Both the radiology report and surgical notes were reviewed in a blinded fashion. Hunter and colleagues recorded a lesion as correctly localized in cases where a single abnormal parathyroid gland was found at surgery in the same location as predicted by CT.

 A total of 138 of the 143 patients had a single abnormal parathyroid gland at surgery. CT delivered 93.7 percent accuracy in identifying the side a single abnormal gland in 134 of the 143 patients.

“4D CT is an accurate method for the presurgical localization of parathyroid adenoma in patients with single-gland primary hyperthyroidism and has the potential to be the sole imaging examination for this purpose,” concluded Hunter et al. The benefits to the approach, continued the authors, include reduced costs, elimination of duplicate exams and improved localization accuracy.