Ultrasonographic diagnosis of parathyroid glands and percutaneous ethanol injection therapy.

The first choice for imaging diagnosis of parathyroid gland (PTG) abnormalities is ultrasonography with a high-frequency probe. The patient must be positioned correctly when performing either imaging or percutaneous ethanol injection (PEIT) of the PTG. The enlarged PTGs are examined by ultrasonic tomography using 3D measurements, and it is important to evaluate blood flow; the PTGs are hypervascular in comparison with a nodular lesion of the thyroid. Based on the 3D data, the estimated volume of the gland is calculated (a x b x c x pi/6), from which the volume of ethanol to be injected is determined. The operator performing the puncture should be skilled in interventional ultrasonography, including needle biopsy of superficial organs, because when the PTG enlargement is advanced, ethanol must be injected in several steps while checking for residual blood flow. After locating the tip of the needle by ultrasonography, the ethanol is injected, the jet echoes that spread from the tip of the needle are confirmed, and when there is no leakage from the gland, a volume of ethanol corresponding to approximately 50% of the volume of the enlarged gland is injected. If residual blood flow is observed, additional ethanol is injected at the site. After completion of PEIT of the PTG, colour Doppler imaging is repeated and, if there is no blood flow, then the procedure is considered to be successful.