Can intravoxel incoherent motion diffusion-weighted imaging characterize the cellular injury and microcirculation alteration in hepatic ischemia-reperfusion injury? An animal study.
To investigate whether intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) can be used to quantitatively analyze the cellular injury and microcirculation alterations in hepatic ischemia-reperfusion injury (HIRI).
Thirty-two New Zealand white rabbits were randomly and equally assigned to the sham group, 1-hour, 4-hour, and 12-hour groups according to the reperfusion time after 1 hour of ischemia using a 70% liver ischemia-reperfusion injury model. All the animals underwent IVIM-DWI with 12 b values at 1.5T. The imaging parameters (IVIM parameters and apparent diffusion coefficient [ADC]) among different groups were compared. The correlations between imaging parameters and histological scores, and the ratio of serum aspartate aminotransferase to serum alanine aminotransferase (serum AST/ALT) were analyzed.
During the first hour of HIRI, true diffusion coefficient (D) and ADC significantly decreased (P < 0.05), while there was no significant decrease in perfusion fraction (f) (P = 0.708). There was fair to good correlation between histological scores and f (rs = -0.493 with the sham cases excluded, and -0.682 with all cases, both P < 0.05) and ADC (rs = -0.479 with the sham cases excluded, and -0.766 with all cases, both P < 0.05). There was no correlation between imaging parameters and serum AST/ALT with the sham cases excluded (P = 0.673 for f, 0.568 for D, 0.403 for ADC), and good correlation between D, ADC, and serum AST/ALT (r = 0.747 and 0.748, both P < 0.001) with all cases.
IVIM-DWI can quantitatively characterize an animal model of HIRI, with D and ADC sensitive in early detection of cellular injury, as well as fair to good correlation between f, ADC, and microcirculation alteration. J. Magn. Reson. Imaging 2016;43:1327-1336.
Ye W
，Li J
，Guo C
，Chen S
，Liu YB
，Liu Z
，Wu H
，Wang G
，Liang C
... -
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Intravoxel Incoherent Motion and Dynamic Contrast-Enhanced Magnetic Resonance Imaging to Early Detect Tissue Injury and Microcirculation Alteration in Hepatic Injury Induced by Intestinal Ischemia-Reperfusion in a Rat Model.
Intravoxel incoherent motion (IVIM) can provide quantitative information about water diffusion and perfusion that can be used to evaluate hepatic injury, but it has not been studied in hepatic injury induced by intestinal ischemia-reperfusion (IIR). Dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) can provide perfusion data, but it is unclear whether it can provide useful information for assessing hepatic injury induced by IIR.
To examine whether IVIM and DCE-MRI can detect early IIR-induced hepatic changes, and to evaluate the relationship between IVIM and DCE-derived parameters and biochemical indicators and histological scores.
Prospective pre-clinical study.
Forty-two male Sprague-Dawley rats.
IVIM-diffusion-weighted imaging (DWI) using diffusion-weighted echo-planar imaging sequence and DCE-MRI using fast spoiled gradient recalled-based sequence at 3.0 T.
All rats were randomly divided into the control group (Sham), the simple ischemia group, the ischemia-reperfusion (IR) group (IR1h, IR2h, IR3h, and IR4h) in a model of secondary hepatic injury caused by IIR, and IIR was induced by clamping the superior mesenteric artery for 60 minutes and then removing the vascular clamp. Advanced Workstation (AW) 4.6 was used to calculate the imaging parameters (apparent diffusion coefficient [ADC], true diffusion coefficient [D], perfusion-related diffusion [D* ] and volume fraction [f]) of IVIM. OmniKinetics (OK) software was used to calculate the DCE imaging parameters (Ktrans , Kep , and Ve ). Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were analyzed with an automatic biochemical analyzer. Superoxide dismutase (SOD) activity was assessed using the nitro-blue tetrazolium method. Malondialdehyde (MDA) was determined by thiobarbituric acid colorimetry. Histopathology was performed with hematoxylin and eosin staining.
One-way analysis of variance (ANOVA) and Bonferroni post-hoc tests were used to analyze the imaging parameters and biochemical indicators among the different groups. Pearson correlation analysis was applied to determine the correlation between imaging parameters and biochemical indicators or histological score.
ALT and MDA reached peak levels at IR4h, while SOD reached the minimum level at IR4h (all P < 0.05). ADC, D, D* , and f gradually decreased as reperfusion continued, and Ktrans and Ve gradually increased (all P < 0.05). The degrees of change for f and Ve were greater than those of other imaging parameters at IR1h (all P < 0.05). All groups showed good correlation between imaging parameters and SOD and MDA (r[ADC] = 0.615, -0.666, r[D] = 0.493, -0.612, r[D* ] = 0.607, -0.647, r[f] = 0.637, -0.682, r[Ktrans ] = -0.522, 0.500, r[Ve ] = -0.590, 0.665, respectively; all P < 0.05). However, the IR groups showed poor or no correlation between the imaging parameters and SOD and MDA (P [Ktrans and MDA] = 0.050, P [D and SOD] = 0.125, P [the remaining imaging parameters] < 0.05). All groups showed a positive correlation between histological score and Ktrans and Ve (r = 0.775, 0.874, all P < 0.05), and a negative correlation between histological score and ADC, D, f, and D* (r = -0.739, -0.821, -0.868, -0.841, respectively; all P < 0.05). For the IR groups, there was a positive correlation between histological score and Ktrans and Ve (r = 0.747, 0.802, all P < 0.05), and a negative correlation between histological score and ADC, D, f, and D* (r = -0.567, -0.712, -0.715, -0.779, respectively; all P < 0.05).
The combined application of IVIM and DCE-MRI has the potential to be used as an imaging tool for monitoring IIR-induced hepatic histopathology.
1 TECHNICAL EFFICACY STAGE: 2.
Yang J
，Meng M
，Pan C
，Qian L
，Sun Y
，Shi H
，Shen Y
，Dou W
... -
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Intravoxel incoherent motion (IVIM) in evaluation of breast lesions: comparison with conventional DWI.
To obtain perfusion as well as diffusion information in normal breast tissues and breast lesions from intravoxel incoherent motion (IVIM) imaging with biexponential analysis of multiple b-value diffusion-weighted imaging (DWI) and compare these parameters to apparent diffusion coefficient (ADC) obtained with monoexponential analysis in their ability to discriminate benign lesions and malignant tumors.
In this prospective study, informed consent was acquired from all patients. Eighty-four patients with 40 malignant tumors, 41 benign lesions, 30 simple cysts and 39 normal breast tissues were imaged at 1.5 T utilizing contrast-enhanced magnetic resonance imaging (MRI) and DWI using 12 b values (range: 0-1000 s/mm(2)). Tissue diffusivity (D), perfusion fraction (f) and pseudo-diffusion coefficient (D*) were calculated using segmented biexponential analysis. ADC (b = 0 and 1000 s/mm(2)) was calculated with monoexponential fitting of the DWI data. D, f, D* and ADC values were obtained for normal breast tissues, simple cysts, benign lesions and malignant tumors. Receiver operating characteristic analysis was performed for all DWI parameters.
There was good interobserver agreement on the measurements between the 2 observers. D values were significantly different among malignant tumors, benign lesions, simple cysts and normal breast tissues (P = 0.000) and it was the same result for f, D* and ADC values. Further comparisons of these 4 parameters between every single pair were as the following. D and ADC values of malignant tumors were significantly smaller than those of benign lesions, simple cysts and normal tissues (P = 0.000, respectively). The f value of malignant tumors was significantly higher than that of benign lesions, simple cysts and normal breast tissues (P = 0.001, P = 0.000, and P = 0.000). D and ADC values demonstrated higher sensitivity and specificity in differentiating benign lesions and malignant tumors, with area under the curve (AUC) of 0.952 and 0.945, respectively, while f and D* with the lower AUC of 0.723 and 0.630, respectively. Combining f and D values had a sensitivity up to 98.75%.
DWI response curves in malignant tumors, benign lesions and normal fibroglandular tissues are found to be biexponential fit in comparison with the monoexponential fit for simple cysts. IVIM provides separate quantitative measurement of D for cellularity and f and D* for vascularity and is helpful for differentiation between benign and malignant breast lesions.
Liu C
，Liang C
，Liu Z
，Zhang S
，Huang B
... -
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Intravoxel incoherent motion diffusion-weighted imaging of hepatocellular carcinoma: Is there a correlation with flow and perfusion metrics obtained with dynamic contrast-enhanced MRI?
To assess the correlation between intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) metrics in hepatocellular carcinoma (HCC) and liver parenchyma.
Twenty-five patients with HCC (M/F 23/2, mean age 58 years) underwent abdominal MRI at 1.5 or 3.0T, including IVIM-DWI (with 16 b-values) and DCE-MRI (3D FLASH sequence, mean temporal resolution of 2.3 sec). IVIM-DWI parameters (pseudodiffusion coefficient, D*, diffusion coefficient, D, and perfusion fraction, PF) were quantified in HCC lesions and liver parenchyma using a Bayesian fitting algorithm. DCE-MRI parameters (arterial flow, Fa , portal flow, Fp , total flow, Ft , mean transit time, MTT, distribution volume, DV, and arterial fraction, ART) were quantified using a dual-input single-compartment model. Correlations between IVIM-DWI and DCE-MRI parameters were assessed using a Spearman correlation test.
Thirty-three HCC lesions (average size 5.0 ± 3.6 cm) were analyzed. D, D*, and PF were all significantly lower in HCC vs. liver (P < 0.05). Significantly higher Fa and ART and lower Fp were observed in HCC vs. liver (P < 0.001). Significant moderate to strong negative correlations were observed between ART and D* (r = -0.443, P = 0.028), ART and PF (r = -0.536, P = 0.006), ART and PFxD* (r = -0.655, P < 0.001), Fa and PF (r = 0.455, P = 0.023), and Fa and PFxD* (r = -0.475, P = 0.018) in liver parenchyma. There was no significant correlation between IVIM-DWI and DCE-MRI metrics in HCC lesions.
IVIM-DWI and DCE-MRI provide nonredundant information in HCC, while they correlate in liver parenchyma. These findings may be secondary to predominant portal inflow in the liver and tortuous vasculature and tissue heterogeneity in tumors. J. MAGN. RESON. IMAGING 2016;44:856-864.
Hectors SJ
，Wagner M
，Besa C
，Bane O
，Dyvorne HA
，Fiel MI
，Zhu H
，Donovan M
，Taouli B
... -
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