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Use of 3D Arterial Spin Labeling to Evaluate Renal Perfusion in Patients with Chronic Kidney Disease1Radiology, Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China, 2Nephrology, Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China, 3MR Applications Development, Siemens Healthcare, Erlangen, Germany, 4MR Applications Development, Siemens Shenzhen Magnetic Resonance Ltd., Shenzhen, China
Synopsis
The purpose of this study is to evaluate the
effectiveness of 3D PASL and 3D pCASL in assessing RBF in both the renal cortex
and medulla of CKD patients and healthy volunteers. The results showed that RBF
maps derived from 3D pCASL had significantly better image quality than RBF maps
derived from 3D PASL. 3D pCASL has the potential to become a novel non-invasive
and non-contrast MRI technique to assess renal cortical and medullary
perfusion.
Introduction
Functional renal failure can be fatal for decompensated chronic kidney disease (CKD) patients. Evaluation of renal blood flow (RBF) is essential for establishing accurate CKD staging and appropriate treatment to attenuate progression to end stage renal disease. Different arterial spin labeling (ASL) imaging techniques such as pulsed ASL (PASL) and pseudo-continuous ASL (pCASL) have already been used to evaluate the RBF of patients with renal masses, arterial stenoses, and allografts that are not visible on conventional non-contrast MRI[1]. The purpose of this study is to evaluate the effectiveness of 3D PASL and 3D pCASL in the assessment of RBF in both the renal cortex and medulla of CKD patients and healthy volunteers.Methods
This experiment was approved by our ethics committee. Informed consent was obtained from all participants. CKD patients Stage 1(S1) to Stage 4 (S4) (n = 4, 9, 11, 7 for S1, S2, S3, and S4 respectively, total n = 31) and healthy volunteers (n = 10) underwent MRI on a 3T MR scanner (MAGNETOM Skyra; Siemens Healthcare, Erlangen, Germany) using a dedicated 18-channel body coil and an integrated spine coil. Prototype sequences with PASL and pCASL labelling were used with a 3D Turbo Gradient Spin Echo (TGSE) data acquisition module[2]. Detailed parameters are shown in Table 1. 3D motion correction was applied for the generation of a perfusion map. Image quality of both PASL and pCASL images were scored (0 - poor, 1 - moderate, 2 - good and 3 - excellent) and compared. Only RBF maps with acceptable image quality scores (≥ 1) were used for analyses regarding RBF. RBF of the renal cortex and medulla were measured on three central slices of every RBF map and compared within each group. RBF values were compared between CKD patients and volunteers and between CKD patients at different stages. Pearson correlation test was used to evaluate the correlations between RBF at the renal cortex and medulla and estimated glomerular filtration rate (eGFR) and between at the renal cortex and medulla and serum creatinine level (SCr) for CKD patients.Results
The image quality scores, expressed as median[P25, P75] , were significantly higher with pCASL(CKD: 2[1, 3], volunteers: 3[2, 3]) than those with PASL (CKD: 1[0, 1], volunteers: 1[1.5, 2.75]) for both CKD patients (P < 0.001) and healthy volunteers (P = 0.005). Thus, only the pCASL RBF maps were used for further analyses. RBF values in the cortex were significantly higher than those in the medulla for both CKD patients (P < 0.001) and volunteers (P < 0.001). RBF values in the cortex of CKD patients of S2 to S4 and in the medulla of S2 to S3 were all significantly lower than those of volunteers (Table 2). Among S2 to S4 of CKD patients, significant differences in RBF in both the cortex and medulla were found (χ2 = 22.130, P = 0.000; medulla: χ2 = 17.098, P = 0.001). RBF values in CKD S1 and S2 patients were significantly higher than those of S3 and S4 patients in both the cortex (S1 vs S3: P = 0.004；S1 vs S4: P = 0.008; S2 vs S3: P = 0.000；S2 vs S4: P = 0.001) and medulla (P = 0.022, 0.014, 0.003, 0.003 for S1 vs S3, S1 vs S4, S2 vs S3, S2 vs S4, respectively) (Fig 1, Table 2). A significant positive correlation between RBF and eGFR was demonstrated in both the cortex and the medulla of CKD patients (Pearson’s rho, cortex: r = 0.822, P = 0.000; medulla: r = 0.790, P = 0.000) (Fig.2). A significant negative correlation was found between RBF and SCr (Pearson’s rho, cortex: r = -0.712, P = 0.000; medulla: r = -0.653, P = 0.000).Discussion and Conclusion
Several previous studies have shown that ASL can be used to evaluate renal tissue perfusion[4,5]. However, this technique presents many challenges, such as sufficient background noise, subject artifact, and lack of consensus regarding labeling strategy and analysis approach[1]. To address these challenges, both PASL and pCASL were performed with a TGSE data acquisition module in free-breathing mode with background suppression in our study. Additionally, inline 3D motion correction was applied for perfusion map calculation. Our study showed that the image quality of pCASL was superior to that of PASL. Significant positive correlations between eGFR and pCASL-derived RBF, and negative correlations between SCr and pCASL-derived RBF in CKD patients were also demonstrated. Hence, pCASL can be used as a non-invasive and non-contrast MRI technique to assess renal perfusion for CKD patients.Acknowledgements
No acknowledgement found.References
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2 Günther M, Oshio K, Feinberg DA (2005) Single-Shot 3D Imaging Techniques Improve Arterial Spin Labeling Perfusion Measurements. Magn Reson Med 54:491-498
3 Levin A, Stevens PE, Bilous RW, et al (2013) Kidney disease: Improving global outcomes (KDIGO) CKD work group. KDIGO 2012 clinical practice guideline for the evaluation and management of chronic kidney disease. 1 ed. Vol. 3. London: Nature Publishing Group:1–150
4 Cai YZ, Li ZC, Zuo PL, Pfeuffer J, Li YM, Liu F, Liu RB (2017) Diagnostic value of renal perfusion in patients with chronic kidney disease using 3D arterial spin labeling. J Magn Reson Imaging 46:589-594
5 Li X, Auerbach EJ, Van de Moortele PF, Ugurbil K, Metzger GJ (2018) Quantitative single breath-hold renal arterial spin labeling imaging at 7T. Magn Reson Med 79:815-825
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