Arterial spin labeling MRI for assessment of perfusion in native and transplanted kidneys

Abstract

Purpose-To apply a magnetic resonance (MR) arterial spin labeling (ASL) technique to evaluate kidney perfusion in native and transplanted kidneys.Materials and Methods-This study was compliant with the Health Insurance Portability and Accountability Act (HIPAA) and approved by the institutional review board. Informed consent was obtained from all subjects. Renal perfusion exams were performed at 1.5 T in a total of 25 subjects: 10 with native and 15 with transplanted kidneys. A flow-sensitive alternating inversion recovery (FAIR) ASL sequence was performed with respiratory triggering in all subjects and under free-breathing conditions in five transplant subjects. Thirty-two control/tag pairs were acquired and processed using a single-compartment model. Perfusion in native and transplanted Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript kidneys was compared above and below an estimated glomerular filtration rate (eGFR) threshold of 60 ml/min/1.73m 2 and correlations with eGFR were determined.Results-In many of the transplanted kidneys, major feeding vessels in the coronal plane required a slice orientation sagittal to the kidney. Renal motion during the examination was observed in native and transplant subjects and was corrected with registration. Cortical perfusion correlated with eGFR in native (r=0.85, p=0.002) and transplant subjects (r=0.61, p=0.02). For subjects with eGFR≥60 ml/min/1.73m 2 , native kidneys demonstrated greater cortical (p=0.01) and medullary (p=0.04) perfusion than transplanted kidneys. For subjects with eGFR<60 ml/min/ 1.73m 2 , native kidneys demonstrated greater medullary perfusion (p=0.04) compared to transplanted kidneys. Free-breathing acquisitions provided renal perfusion measurements that were slightly lower compared to the coached/triggered technique, although no statistical differences were observed.Conclusion-In conclusion, FAIR-ASL was able to measure renal perfusion in subjects with native and transplanted kidneys, potentially providing a clinically viable technique for monitoring kidney function.

Measurement of Kidney Perfusion in Critically Ill Patients

“…ASL allows imaging of the renal arteries despite their complex orientation [56]. A fairly good correlation of ASL with P AH clearance has been reported [57] and some applications after ren al transpl antation or in renal artery stenosis [55,58] have been proposed. One of the main interests of ASL is its ability to draw parametric maps of relative perfusion (Figure 2) enabling clinicians to study geographical intra-organ diff erences in pe rfus ion as opposed to overall organ blood fl ow.…”

Measurement of kidney perfusion in critically ill Patients

“…A perfusion-weighted image can be produced by subtracting an image in which inflowing spins have been labeled from an image in which spin labeling has not been used (Figure 2). [55]. ASL allows imaging of the renal arteries despite their complex orientation [56].…”

“…ASL allows imaging of the renal arteries despite their complex orientation [56]. A fairly good correlation of ASL with PAH clearance has been reported [57] and some applications after renal transplantation or in renal artery stenosis [55,58] have been proposed. One of the main interests of ASL is its ability to draw parametric maps of relative perfusion (Figure 2) enabling clinicians to study geographical intra-organ differences in perfus ion as opposed to overall organ blood flow.…”

“…Tagged image (a) with moving spins labeled; control image (b) ; difference between a and b representing the perfusion-weighted image (c) ; and resulting perfusion map (d) shown in units of ml/min per 100 g (adapted from [55] with permission).…”

Arterial and portal venous liver perfusion using selective spin labelling MRI

“…Its application has been extended to organs other than the brain and oncological imaging. In abdominal organs, SL-MRI is almost exclusively performed in the kidneys [6][7][8][9]. Abdominal SL-MRI is especially challenged by possible misalignment between the control and label images.…”