Measuring Kidney Perfusion, pH, and Renal Clearance Consecutively Using MRI and Multispectral Optoacoustic Tomography

Abstract

Purpose: To establish multi-modal imaging for the assessment of kidney pH, perfusion, and clearance rate using magnetic resonance imaging (MRI) and multispectral optoacoustic tomography (MSOT) in healthy mice. Kidney pH and perfusion values were measured on a pixel-by-pixel basis using the MRI acidoCEST and FAIR-EPI methods. Kidney filtration rate was measured by analyzing the renal clearance rate of IRdye 800 using MSOT. To test the effect of one imaging method on the other, a set of 3 animals were imaged with MSOT followed by MRI, and a second set of 3 animals were imaged with MRI followed by MSOT. In a subsequent study, the reproducibility of pH, perfusion, and renal clearance measurements were tested by imaging 4 animals twice, separated by 4 days. The contrast agents used for acidoCEST based pH measurements influenced the results of MSOT. Specifically, the exponential decay time from the kidney cortex, as measured by MSOT, was significantly altered when MRI was performed prior to MSOT. However, no significant difference in the cortex to pelvis area under the curve (AUC) was noted. When the order of experiments was reversed, no significant differences were noted in the pH or perfusion values. Reproducibility measurements demonstrated similar pH and cortex to pelvis AUC; however, perfusion values were significantly different with the cortex values being higher and the pelvic values being lower in the second imaging time. We demonstrate that using a combination of MRI and MSOT, physiological measurements of pH, blood flow, and clearance rates can be measured in the mouse kidney in the same imaging session.

DHHC21 Deficiency Attenuates Renal Dysfunction During Septic Injury

“…Another novel aspect of our study is the utilization of MSOT to evaluate kidney perfusion and function during septic injury. MSOT has been reported as a label-free method to measure the perfusion of different organs and a reliable imaging technique to determine kidney function 28,32,45 . Compared to Doppler owmeter which does not allow visualization of microvasculature 45 , MSOT generates images with high spatial resolution at 150 µm while providing quantitative assessment of the perfusion status in the kidney microvasculature.…”

“…MSOT relies on the photoacoustic effect and detects the ultrasound signals produced by the thermal expansion of tissues/molecules when excited by near-infrared (NIR, 680-950nm) laser pulses 27 . NIR dye IRDye800CW, which is exclusively excreted by the kidneys 28,29 , was injected intravenously 24 hours after sham procedure and CLP-induced septic injury. As shown in Fig.…”

Development of concurrent magnetic resonance imaging and volumetric optoacoustic tomography: A phantom feasibility study

“…Even though multimodal imaging with a separate acquisition of OAT and MRI data has previously been reported [22–24], a truly hybrid system for concurrent OAT‐MRI imaging has so far not been developed. This work is the first to demonstrate the basic feasibility of simultaneous OAT and MRI recordings.…”

Photoacoustic Imaging in Evaluating Early Intestinal Ischemia and Reperfusion Injury with Rat Models

“…However, its wide application is limited by the complexity of operation methods, the use of special instruments and the high cost of inspection. CT and MRI are also used to predict or measure intestinal viability, and have certain diagnostic value for intestinal ischemia injury [22,23] . However, these imaging techniques usually produce motion artifacts due to the patient's heartbeat and respiration [24] .…”