An Assessment of Enhancement Patterns in Abnormal Parathyroid Glands on Three-Phase CT Imaging.

Background Four-dimensional computed tomography (4DCT) is increasingly used in the investigation of primary hyperparathyroidism. The objective of this study was to identify and analyse the usefulness of different enhancement patterns on 4DCT to improve its sensitivity. Methodology Retrospective data were collected on 100 glands. A consultant head and neck radiologist measured the Hounsfield units (HU) of the parathyroid gland and surrounding normal thyroid tissue in the pre-contrast, arterial and venous phases. Each gland was grouped according to the enhancement pattern, and the percentage change in HU was also calculated between the three phases. Results Thirty-five parathyroid glands demonstrated enhancement higher than the thyroid gland in the arterial phase and lower in the delayed phase and were placed into group A. Four parathyroid glands demonstrated enhancement higher than the thyroid gland in the arterial phase and also higher in the delayed phase and were placed into group B. Fifty-nine parathyroid glands demonstrated enhancement lower than the thyroid gland in the arterial phase and also lower in the delayed phase and were placed into group C. Two parathyroid glands demonstrated enhancement lower than the thyroid gland in the arterial phase and higher in the delayed phase and were placed into group D. Conclusions This study demonstrated that the classically described enhancement pattern of the parathyroid gland is not always present or the most frequent, thereby showing that the enhancement pattern cannot be relied upon in isolation. Instead, a thorough understanding of anatomy, embryology and possible ectopic gland locations is essential.