First successful imaging without contrast agent of the complex structure of the kidneys

A research team from POSTECH (Pohang University of Science and Technology) studied kidney diseases using ultrafast ultrasound that captures 1,000 images in just one second.

The research team performed imaging of the three-dimensional microvasculature of the kidneys using ultrafast ultrasound. Their technique is attracting attention because it is able to visualize the entire renal microvasculature without any contrast agent. Results are published Advanced science.

The kidney plays a role in filtering waste and removing unwanted substances from the bloodstream. Conditions such as hypertension and diabetes can compromise this vital function, leading to kidney failure, an irreversible disease requiring lifelong treatment with artificial hemodialysis or donor kidney transplantation.

Given the direct link between blood perfusion in the kidneys and their filtration function, microvascular imaging can be a key indicator for preventing and curing kidney failure.

Representative contemporary medical imaging methods like CT (computed tomography) and MRI (magnetic resonance imaging) have limitations in capturing fine vascular structures due to their resolution and sensitivity constraints. Additionally, the use of contrast agents in these methods is limited due to their potentially fatal side effects in patients with renal insufficiency.

In contrast, ultrasound imaging, considered safe enough for fetal monitoring, uses the Doppler effect to measure the speed and direction of blood flow in real time without the need for contrast agents.

However, current imaging speed has limitations to capture fine blood vessels with sufficient sensitivity. The research team improved microvascular sensitivity using ultrafast ultrasound acquisition, capturing 1,000 images per second, a speed more than 100 times faster than conventional ultrasound imaging.

Using this technique, researchers achieved a world first by imaging the entire three-dimensional vascular network of the renal artery, vein, and interlobular arteries and veins 167 μm (micrometers) thick in the renal cortex without use a contrast agent.

Furthermore, they continuously observed renal vascular changes in an animal model induced by renal failure, performing a multivariate analysis using hemodynamic and vascular morphological indicators. The results revealed a sharp decrease in renal blood flow in acute renal failure, while in diabetic nephropathy they identified chronic vascular degeneration of the kidneys accompanied by vascular distortion.

Professor Chulhong Kim explained: “The system allows us to understand the pathophysiology of diseases leading to kidney failure, thereby enabling the observation of vascular changes before and after kidney transplantation. It has significant potential to be used to study blood circulation and functional impairments in various organs. , including the digestive system, circulatory system and cerebral nervous system.