Preoperative four-dimensional computed tomography imaging and intraoperative findings for parathyroid disease are not always in agreement, a retrospective study has found.
Among patients with primary hyperparathyroidism who underwent preoperative four-dimensional computed tomography (4-D CT) followed by parathyroidectomy, multigland disease was the most strongly associated with discordance between the scan and the intraoperative findings, according to the study.
“Parathyroid 4-D CTs have emerged as one of the most accurate preoperative imaging modalities to localize abnormal parathyroid glands,” wrote researchers led by Shonan Sho, MD (JAMA Surg. 2017 Aug 9.). “Despite this use, missed lesions and incorrect localization still occur.”
In what is believed to be the first study of its kind, Dr. Sho of the section of endocrine surgery at the University of California, Los Angeles, and his associates prospectively evaluated factors associated with discordance between preoperative four-dimensional computed tomographic scans and intraoperative findings. They examined data from 411 patients with primary hyperparathyroidism who underwent 4-D CTs followed by parathyroidectomy at UCLA from Sept. 1, 2011, through Oct. 31, 2016. The mean age of patients was 59, 79% were female, and 30% had discordance between preoperative 4-D CTs and intraoperative findings.
When the researchers compared concordant cases with discordant cases, they found that discordant cases had higher frequencies of multigland disease (24.3% vs. 66.7%, respectively; P less than .001) and multinodular goiter or thyroid nodule (29.2% vs. 40.7%; P = .02). “Thyroid nodules can mimic parathyroid adenomas because they can occur in similar locations and appear oval or round, and they can have enhancement characteristics similar to those of parathyroid adenomas,” Dr. Sho and his associates wrote. “The addition of ultrasound may enable correct identification of abnormal parathyroid glands in a patient with thyroid nodules.”
The investigators also found that missed parathyroid lesions tended to be smaller than 10 mm in size and were more likely to be in the inferior position.
Multivariable analysis revealed the analysis risk factors for discordant 4-D CT findings: multigland disease (odds ratio, 7.63), parathyroid lesion in the inferior position (OR, 6.82), parathyroid lesion size of 10 mm or less (OR, 4.37), and multinodular goiter or thyroid nodule (OR, 1.82). The researchers concluded, “In the case of a negative 4-D CT, the surgeon may elect to allot additional operative time for what may be a more difficult case. Or, after considering the likelihood of MGD [multigland disease] based on biochemical values and the 4-D CT result, the surgeon may consider having a more detailed discussion with the patient regarding the potential need for subtotal parathyroidectomy. During surgery, if the surgeon is not finding the culprit glands or if the PTH [parathyroid hormone] level is not dropping, he or she should recall that discordance between intraoperative findings and the 4-D CT results is likely to be explained by MGD, an inferior gland that is flattened against the surface of the thyroid gland, or, less commonly, an intrathyroidal gland.”
They acknowledged certain limitations of the study, including its single-center, retrospective design; the fact that calcium levels were not available in all patients; and the fact that the 4-D CT technique remains novel.
The investigators reported having no relevant financial disclosures.