Preoperative localization of the diseased parathyroid gland(s) in primary hyperparathyroidism
allows for minimally invasive surgery. This study was designed to establish the optimal first-line preoperative imaging modality.
Patients and Methods
Ninety-one patients were studied consecutively in a prospective head-to-head comparison of dual isotope (99m
Tc-MIBI vs 123
(PS), dual-phase PS, 4-dimensional (4D) CT, and ultrasonography
(US). Surgery, histological confirmation, and postoperative normalization of Ca++
and parathyroid hormone were the reference standard.
Ninety-seven hyperfunctioning parathyroid glands (HPGs) were identified by the reference standard. Sensitivity and specificity for subtraction
PS, dual-phase PS, 4D-CT
, and US were 93%, 65%, 58%, and 57% as well as 99%, 99.6%, 86%, and 95%, respectively. Interrater agreement was excellent for subtraction
PS (κ = 0.96) while only fair for 4D-CT
(κ = 0.34). Pinhole imaging and subtraction
of delayed images (the latter especially in case of a nodular thyroid gland) increased the sensitivity of subtraction
PS. SPECT/low-dose CT did not increase sensitivity but aided in the exact localization of the HPGs. Of 7 negative subtraction
PS studies, 4D-CT
and US were able to locate 3 and 1 additional HPGs, respectively.
Dual isotope pinhole subtraction
PS has higher diagnostic accuracy compared with dual-phase PS, 4D-CT
, and US as a first-line imaging study in primary hyperparathyroidism
. In case of a negative scintigraphy
or suspicion of multiglandular disease, 4D-CT
and/or US is recommended as a second-line modality. However, diagnostic algorithms should be adapted in accordance with local availability and expertise.