Search

Background: Chronic allograft damage (CAD) is the leading cause of long-term graft dysfunction. A noninvasive method that can diagnose CAD early and monitor its development is needed.Methods: Kidneys from Fisher rats were transplanted into Lewis rats to establish a CAD model (n = 20). The control group underwent syngeneic kidney transplantation (n = 20). The serum creatinine of the rats was monitored. At 4, 12, and 20 weeks after modeling, a magnetic resonance imaging (MRI) examination was performed. The apparent diffusion coefficient (ADC), pseudo diffusion coefficient (D*), true diffusion coefficient (D) and perfusion fraction (f) of the two groups were analyzed. Chronic allograft damage index (CADI) scoring was used to evaluate the transplanted kidney specimens. Immunohistochemistry was used to detect the expression of fibrosis markers in the transplanted kidney tissues and to analyze their correlations with all MRI parameters.Results: The transplanted kidneys in the experimental group developed CAD changes before the appearance of elevated creatinine. The MRI parameters in the experimental group [ADC (1.460 ± 0.109 VS 2.095 ± 0.319, P < 0.001), D (1.435 ± 0.102 VS 1.969 ± 0.305, P < 0.001), and f (26.532 ± 2.136 VS 32.255 ± 4.013, P < 0.001)] decreased, and D* (20.950 ± 2.273 VS 21.415 ± 1.598, P = 0.131) was not significantly different from those in the control group. ADC, D and f were negatively correlated with the CADI and the α-SMA and vimentin expression levels.Conclusion: Intravoxel incoherent motion (IVIM) imaging could detect CAD earlier than creatinine and reflect the degree of fibrosis in grafts quantitatively. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the relationships between imaging parameters derived from intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) and HPV status in oropharyngeal squamous cell carcinoma (OPSCC).Materials and Methods: 73 patients with a new diagnosis of OPSCC were enrolled in the present study. MRI including IVIM-DWI with nine b value (range 0-800 s/mm2) was acquired in all patients. Primary tumor (PT) and the largest metastatic lymph node (LN), if present, were volumetrically contoured and the tissue diffusion coefficient Dt, perfusion fraction f and perfusion-related diffusion coefficient D* were estimated by a bi-exponential fit. The apparent diffusion coefficient (ADC) was also estimated by a mono-exponential fit. The predictive power of the most relevant patient/tumor characteristics and image-based features in determining the HPV status was assessed.Results: 67 PTs and 67 metastatic LNs were analyzed. Significant differences in ADC and Dt values among HPV-positive and HPV-negative patients were found for PTs (p = 0.003 and p < 0.001, respectively), while a trend toward significance in Dt was reported for LNs (p = 0.066). The perfusion-related parameters, f, D* and D*× f, were not related to HPV status. The best predictive model for HPV positivity was obtained combining alcohol intake and smoke habits with Dt values of PTs (accuracy = 80.8%, sensitivity = 85.7%, specificity = 64.7%).Conclusion: Significant correlations were found between IVIM-DWI and HPV status in OPSCCs. The perfusion-free diffusion coefficient, Dt, may better reflect the HPV-related tumor differences compared to ADC, whereas the perfusion-related parameters were not able to reliably discriminate HPV-positive from HPV-negative OPSCC. [ABSTRACT FROM AUTHOR]

Background: Intravoxel incoherent motion magnetic resonance imaging (IVIM) enables non-invasive measurement of brain perfusion. Purpose: To investigate whether IVIM could be used to evaluate the hemodynamic disturbance of Moyamoya disease (MMD) by comparison with the gold-standard 15O-gas positron emission tomography (PET) method. Material and Methods: Ten consecutive patients with MMD (six women; mean age = 42.8 years) and 10 age-matched healthy controls were evaluated by diffusion-weighted images with 12 different b values in the range of 0–900 s/mm2 and 15O-gas PET. Tomographic maps of IVIM parameters, perfusion fraction (f), pseudo-diffusion coefficient (D*), and f・D*, as well as cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT) maps obtained with PET, were normalized and hemispheric gray and white matter values were calculated. IVIM parametric values were compared with PET parameters and with clinically assessed disease severity. Results: There was significant correlation between D* and MTT (r = –0.74, P < 0.001) and between f・D* and CBF (r = 0.52, P = 0.02) in the cortical areas. The f values in the white matter were significantly higher in symptomatic MMD patients than in healthy controls (P = 0.01). Conclusion: IVIM may be used to non-invasively investigate cerebral hemodynamic impairment in patients with MMD. Further evaluation is needed to establish IVIM usage in clinical settings. [ABSTRACT FROM AUTHOR]

Introduction: Cerebral small vessel disease (cSVD) is associated with microvascular and parenchymal alterations. Intravoxel incoherent motion (IVIM) MRI has been proposed to simultaneously measure both the microvascular perfusion and parenchymal diffusivity. This study aimed to evaluate the application of IVIM in cSVD to assess the microvasculature and parenchymal microstructure., Methods: Seventy-three patients with cSVD (age 70 ± 11 y) and thirty-nine controls (age 69 ± 12 y) underwent IVIM imaging (3T). Group differences of the perfusion volume fraction f and the parenchymal diffusivity D were investigated using multivariable linear regression accounted for age, sex and cardiovascular factors. To examine the relation between the IVIM measures and the disease severity on structural MRI, white matter hyperintensity (WMH) load served as surrogate measure of the disease severity., Results: Patients had a larger f ( p  < 0.024) in the normal appearing white matter (NAWM) than controls. Higher D ( p  < 0.031) was also observed for patients compared with controls in the NAWM and grey matter. Both f ( p  < 0.024) and D ( p  < 0.001) in the NAWM and grey matter increased with WMH load., Conclusions: The increased diffusivity reflects the predicted microstructural tissue impairment in cSVD. Unexpectedly, an increased perfusion volume fraction was observed in patients. Future studies are needed to reveal the precise nature of the increased perfusion volume fraction. IVIM imaging showed that the increases of f and D in cSVD were both related to disease severity, which suggests the potential of IVIM imaging to provide a surrogate marker for the progression of cSVD.