Parathyroid 4D CT and Scintigraphy: What Factors Contribute to Missed Parathyroid Lesions?

Objective: To determine the prevalence of missed lesions for parathyroid 4-dimensional computed tomography (4D CT) and scintigraphy and to describe the factors leading to missed lesions for both modalities.

Study design: Case series with chart review.

Setting: Single center, hospital based.

Subjects and methods: Forty patients undergoing 4D CT and scintigraphy before parathyroidectomy between July 2009 and October 2013 were included. Radiology reports and imaging were reviewed and correlated with operative notes to identify cases with missed lesions and the reasons for those misses. All lesions were then classified according to the following factors: multigland disease, lesion size, patient body weight, and multinodular goiter.

Results: Of the 40 patients, 6 had multigland disease, resulting in 51 lesions; 12 and 29 lesions were missed on 4D CT and scintigraphy, respectively. The sensitivity for detection of all lesions was 76% for 4D CT and 43% for scintigraphy. Sensitivities for single-gland disease were 88% for 4D CT and 50% for scintigraphy. Sensitivities for multigland disease were 53% for 4D CT and 24% for scintigraphy. Rates of multigland disease in patients with missed lesions were 75% on 4D CT and 48% on scintigraphy, as compared with patients with detected lesions, 23% and 18%, respectively (P ≤ .04). Mean weight of lesions missed on 4D CT was 0.3 and 0.6 g in detected lesions (P = .15). Mean weight of lesions missed on scintigraphy was 0.4 and 0.8 g in detected lesions (P = .03).

Conclusion: 4D CT has higher sensitivity than scintigraphy. Missed lesions are more likely to occur with multigland disease for both modalities and in smaller lesions for scintigraphy.