Ultrasound diagnosis of parathyroid adenomas mimicking normal lymph nodes: microvascular clues.

BACKGROUND

Ultrasound (US) is the preferred imaging modality for preoperative localization of primary hyperparathyroidism (PHPT). Parathyroid adenomas may be confused with normal lymph nodes on conventional US. This study aimed to explore the usefulness of microvascular flow imaging (MVFI) in differentiating parathyroid adenomas from normal lymph nodes and compare it with color Doppler flow imaging (CDFI).

METHODS

A total of 34 parathyroid adenomas that appeared peripherally hypoechoic and internally hyperechoic mimicking normal lymph nodes were identified in 34 patients with PHPT, and 34 cervical level III normal lymph nodes from 34 healthy controls were selected for comparison. The ability of CDFI and MVFI to detect the vascular characteristics of parathyroid adenomas were compared.

RESULTS

On CDFI, the detection rates of polar vessels, hilar vessels, and rich vascular in parathyroid adenomas were 44.1%, 8.8%, and 52.9%, respectively. These characteristics in normal lymph nodes showed detection rates of 2.9%, 38.2%, and 8.8%, respectively. On MVFI, the detection rates of polar vessels, hilar vessels, and rich vascular in parathyroid adenomas were 82.4%, 5.9%, and 94.1%, respectively. For normal lymph nodes, the detection rates of these characteristics were 5.9%, 76.5%, and 11.8%, respectively. Compared with CDFI, MVFI detected a significantly higher rate of polar vessels and rich vascularity in parathyroid adenomas (82.4% 44.1% and 94.1% 52.9%, P=0.034 and P<0.001), as well as hilar vessels in normal lymph nodes (76.5% 38.2%, P<0.001).

CONCLUSIONS

MVFI more frequently identified polar vessels and rich vascularity in parathyroid adenomas, as well as hilar vessels in lymph nodes, compared to CDFI. This suggests that MVFI may play a better role in differentiating parathyroid adenomas from lymph nodes, contributing to surgical planning in PHPT cases.