Stroke assessment with intravoxel incoherent motion diffusion-weighted MRI

• Published in: NMR in biomedicine Vol. 29; no. 3; pp. 320 - 328
• Main Authors: Suo, Shiteng, Cao, Mengqiu, Zhu, Wanqiu, Li, Lei, Li, Jun, Shen, Fei, Zu, Jinyan, Zhou, Zien, Zhuang, Zhiguo, Qu, Jianxun, Chen, Zengai, Xu, Jianrong
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.03.2016; Wiley Subscription Services, Inc
• Subjects: Adult; Aged; Aged, 80 and over; bi-exponential; Diffusion Magnetic Resonance Imaging - methods; diffusion-weighted imaging; Female; human brain; Humans; intravoxel incoherent motion; Male; Middle Aged; Models, Theoretical; Motion; perfusion; stroke; Stroke - diagnostic imaging; human brain; perfusion; bi-exponential; diffusion-weighted imaging; stroke; intravoxel incoherent motion
• ISSN: 0952-3480; 1099-1492; 1099-1492
• DOI: 10.1002/nbm.3467

Intravoxel incoherent motion (IVIM) diffusion‐weighted MRI can simultaneously measure diffusion and perfusion characteristics in a non‐invasive way. This study aimed to determine the potential utility of IVIM in characterizing brain diffusion and perfusion properties for clinical stroke. The multi‐b‐value diffusion‐weighted images of 101 patients diagnosed with acute/subacute ischemic stroke were retrospectively evaluated. The diffusion coefficient D, representing the water apparent diffusivity, was obtained by fitting the diffusion data with increasing high b‐values to a simple mono‐exponential model. The IVIM‐derived perfusion parameters, pseudodiffusion coefficient D*, vascular volume fraction f and blood flow‐related parameter fD*, were calculated with the bi‐exponential model. Additionally, the apparent diffusion coefficient (ADC) was fitted according to the mono‐exponential model using all b‐values. The diffusion parameters for the ischemic lesion and normal contralateral region were measured in each patient. Statistical analysis was performed using the paired Student t‐test and Pearson correlation test. Diffusion data in both the ischemic lesion and normal contralateral region followed the IVIM bi‐exponential behavior, and the IVIM model showed better goodness of fit than the mono‐exponential model with lower Akaike information criterion values. The paired Student t‐test revealed significant differences for all diffusion parameters (all P < 0.001) except D* (P = 0.218) between ischemic and normal areas. For all patients in both ischemic and normal regions, ADC was significantly positively correlated with D (both r = 1, both P < 0.001) and f (r = 0.541, P < 0.001; r = 0.262, P = 0.008); significant correlation was also found between ADC and fD* in the ischemic region (r = 0.254, P = 0.010). For all pixels within the region of interest from a representative subject in both ischemic and normal regions, ADC was significantly positively correlated with D (both r = 1, both P < 0.001), f (r = 0.823, P < 0.001; r = 0.652, P < 0.001) and fD* (r = 0.294, P < 0.001; r = 0.340, P < 0.001). These findings may have clinical implications for the use of IVIM imaging in the assessment and management of acute/subacute stroke patients. Copyright © 2016 John Wiley & Sons, Ltd. Intravoxel incoherent motion (IVIM) diffusion‐weighted MRI was applied in patients with acute/subacute ischemic stroke. Our results showed that the IVIM bi‐exponential model fitted the diffusion data better than the conventional mono‐exponential model, and demonstrated that the IVIM imaging was capable to evaluate the diffusion and perfusion effects simultaneously in human stroke, in a quantitative and non‐invasive way.