Abstract Objective To assess the severity of secondary hyperparathyroidism (SHPT) using contrast-enhanced ultrasound (CEUS) parametric imaging.Methods 56 SHPT patients who underwent conventional and CEUS examination of the parathyroid gland in our hospital from January 2021 to September 2021

followed by PI imaging analysis. They were divided into light

moderate and severe group as per parathyroid hormone (PTH). After conventional ultrasound measurement of volume and internal echo

CEUS was performed

then PI was used to analyze the video clips and the earliest Arrival Time (AT1)

last Arrival Time (AT1) and travel time (△T) were measured. TIC imaging was used to measure the time of the contrast agent entering the parathyroid (ATm). The quantitative parameters of PI include the perfusion pattem (uniform

centripetal

centrifugal

eccentric)

non-uniform

uniform enhancement

non-enhancement area and enhancement time.Results PI imaging is more recommended to measure the start time of contrast agent entry after mass SHPT imaging. The PI manifestations of light and moderate SHPT were mainly in uniform perfusion pattems

and showed uniform enhancement; The PI manifestations of severe SHPT were mainly centered perfusion pattern and showed uneven enhancement. PI of SHPT in the three groups was almost synchronous with the entry of thyroid contrast agent

and ArT1 of mild SHPT was the earliest.Conclusion The PI model and quantitative parameters can be benefit for the assessment the severity of SHPT.