Localization of small parathyroid adenomas using modified 4-dimensional computed tomography/ultrasound.

Objective: To investigate whether parathyroid gland weight has an impact on the accuracy of preoperative localization of parathyroid adenomas with modified 4 dimensional computed tomography/ultrasound. And to determine if the weight of parathyroid adenomas can be calculated accurately based on the dimensions of the gland on the CT images.

Study Design: Case series with chart review.

Setting: Tertiary care hospital.

Subjects And Methods: One hundred forty-two patients who had a preoperative modified 4-dimensional computed tomography/ultrasound and underwent parathyroidectomy for hyperparathyroidism due to a parathyroid adenoma between 1998 and 2009. Charts were reviewed to identify (1) the sensitivity and specificity for localization of parathyroid adenomas according to gland weight and (2) correlation between preoperative estimate of parathyroid weight and the surgical weight of the parathyroid gland.

Results: Modified 4-dimensional computed tomography/ultrasound displayed 92% sensitivity for localizing adenomas weighing <150 mg to the correct side of the neck (95% confidence interval [CI], 65%-99%), 100% sensitivity for glands weighing 150 to 500 mg (95%-100%), and 98% sensitivity for glands weighing >500 mg (92%-100%). For localization to the correct quadrant of the neck, sensitivity was 75% (95% CI, 47%-91%) for glands weighing <150 mg, 89% (79%-95%) for those weighing 150 to 500 mg, and 94% (85%-97%) for glands weighing >500 mg. A positive correlation was seen between the preoperative weight estimate based on imaging and the operative weight of the gland, with a Pearson correlation coefficient of 0.96.

Conclusion: Modified 4-dimensional computed tomography/ultrasound can closely predict the weight of parathyroid glands preoperatively and has good sensitivity for localization of adenomas, even in glands weighing less than 150 mg.