Lingjie Wu

Metabolic changes in the visual cortex of binocular blindness macaque monkeys: a proton magnetic resonance spectroscopy study.

Purpose To evaluate proton magnetic resonance spectroscopy (1H-MRS) in a study of cross-modal plasticity in the visual cortex of binocular blindness macaque monkeys. Materials and Methods Four healthy neonatal macaque monkeys were randomly divided into 2 groups, with 2 in each group. Optic nerve transection was performed in both monkeys in the experimental group (group B) to obtain binocular blindness. Two healthy macaque monkeys served as a control group (group A). After sixteen months post-procedure, 1H-MRS was performed in the visual cortex of all monkeys. We compared the peak areas of NAA, Cr, Cho, Glx and Ins and the ratios of NAA/Cr, Cho/Cr, Glx/Cr and Ins/Cr of each monkey in group B with group A. Results The peak area of NAA and the NAA/Cr ratio in the visual cortex of monkey 4 in group B were found to be dramatically decreased, the peak area of NAA slightly decreased and the NAA/Cr ratio clearly decreased in visual cortex of monkey 3 in group B than those in group A. The peak area of Ins and the Ins/Cr ratio in the visual cortex of monkey 4 in group B slightly increased. The peak area of Cho and the Cho/Cr ratio in the visual cortex of all monkeys in group B dramatically increased compared with group A. The peak area of Glx in the visual cortex of all monkeys in group B slightly increased compared with group A. Conclusions 1H-MRS could detect biochemical and metabolic changes in the visual cortex and therefore this technique can be used to provide valuable information for investigating the mechanisms of cross-modal plasticity of binocular blindness in a macaque monkey model.

Intravoxel Incoherent Motion MR Imaging in the Differentiation of Benign and Malignant Sinonasal Lesions: Comparison with Conventional Diffusion-Weighted MR Imaging

One hundred thirty-one patients with histologically proved solid sinonasal lesions (56 benign and 75 malignant) who underwent conventional DWI and intravoxel incoherent motion were evaluated. The diffusion coefficient (D), pseudodiffusion coefficient (D*), and perfusion fraction (f) values derived from intravoxel incoherent motion and ADC values derived from conventional DWI were measured and compared. The mean ADC and D values were significantly lower in malignant sinonasal lesions than in benign sinonasal lesions and the mean f value was higher in malignant than in benign lesions. Multiparametric models can significantly improve the cross-validated areas under the curve for the differentiation of sinonasal lesions compared with single-parametric models. The authors conclude that intravoxel incoherent motion appears to be a more effective MR imaging technique than conventional DWI in the differentiation of benign and malignant sinonasal lesions. BACKGROUND AND PURPOSE: Intravoxel incoherent motion is a promising method for the differentiation of sinonasal lesions. This study aimed to evaluate the value of intravoxel incoherent motion in the differentiation of benign and malignant sinonasal lesions and to compare the diagnostic performance of intravoxel incoherent motion with that of conventional DWI. MATERIALS AND METHODS: One hundred thirty-one patients with histologically proved solid sinonasal lesions (56 benign and 75 malignant) who underwent conventional DWI and intravoxel incoherent motion were recruited in this study. The diffusion coefficient (D), pseudodiffusion coefficient (D*), and perfusion fraction (f) values derived from intravoxel incoherent motion and ADC values derived from conventional DWI were measured and compared between the 2 groups using the Student t test. Receiver operating characteristic curve analysis, logistic regression analysis, and 10-fold cross-validation were performed to evaluate the diagnostic performance of single-parametric and multiparametric models. RESULTS: The mean ADC and D values were significantly lower in malignant sinonasal lesions than in benign sinonasal lesions (both P < .001). The mean f value was higher in malignant lesions than in benign lesions (P = .003). Multiparametric models can significantly improve the cross-validated areas under the curve for the differentiation of sinonasal lesions compared with single-parametric models (all corrected P < .05 except the D value). The model of D+f provided a better diagnostic performance than the ADC value (corrected P < .001). CONCLUSIONS: Intravoxel incoherent motion appears to be a more effective MR imaging technique than conventional DWI in the differentiation of benign and malignant sinonasal lesions.

Manganese-enhanced MRI (ME MRI) in evaluation of the auditory pathway in an experimental rat model: ME MRI in evaluation of auditory pathway

This study aimed to explore the optimal dose and manner of administration for visualization of the auditory pathway on manganese‐enhanced MRI (ME MRI). Twenty‐four healthy male Sprague–Dawley rats were randomly divided into three experimental groups (n = 8 for Groups A, B and C). The rats in Groups A, B and C were subjected to MnCl2 injection through the tympanum, inner ear endolymph and perilymph, respectively (0.2 M for four rats and 0.4 M for the others in each group) and observed at 1, 2, 3, 4, 7 and 10 days after the operation with 3.0 T MRI. The signal intensity (SI) and dynamic changes of the auditory pathways at various times, and at two doses through three injection routes, were compared by statistical analysis. Administration of MnCl2 through the perilymph best showed the complete auditory pathway (P < 0.01), whereas administration though the tympanum only demonstrated part of the pathway. The SI was highest at 24 h after administration of the tracer and began to decline at 48 h. The SI of the auditory cortex was higher after the injection of 0.4 M MnCl2 than that of 0.2 M MnCl2. ME MRI best demonstrated the whole auditory pathway at 24 h after the injection of 0.4 M MnCl2 through the perilymph in the rat, which provided an optimal method for the study of ME MRI of the auditory pathway in the animal model.

Preliminary study of diffusion-weighted imaging and magnetic resonance spectroscopy imaging in Kimura disease.

Abstract In this study, we evaluated the value of diffusion-weighted imaging (DWI) and magnetic resonance (MR) spectroscopy imaging (MRSI) combined with computed tomography (CT) and conventional MR imaging (MRI) in the diagnosis of Kimura disease (KD). The clinical data and CT and MRI findings of 5 patients with KD proven by histopathologic examination were retrospectively reviewed. Diffusion-weighted imaging and MRSI were performed at 1.5 T in 3 patients with KD. Apparent diffusion coefficient (ADC) values and the choline/creatine ratio of the lesions were compared with those of the contralateral normal parotid glands. All imaging results were compared with histopathologic findings. The typical features of KD were subcutaneous lesions, continuously infiltrative parotid lesions with or without intraparotid lymphadenopathies, and reactive cervical lymphadenopathies on CT and conventional MRI. On DWI, the ADC values of all subcutaneous and infiltrative parotid lesions were higher compared to those of normal parotid glands, and the ADC values of reactive lymphadenopathies were lower compared to both. The choline/creatine levels of subcutaneous and infiltrative parotid lesions were slightly higher than those of normal parotid glands. In conclusion, DWI and MRSI offer valuable information that may be characteristic of KD, which can highly suggest the diagnosis of KD when combined with morphological imaging.

Differentiation of olfactory neuroblastomas from nasal squamous cell carcinomas using MR diffusion kurtosis imaging and dynamic contrast-enhanced MRI

To evaluate the use of magnetic resonance (MR) diffusion kurtosis imaging (DKI) and dynamic contrast‐enhanced MR imaging (DCE‐MRI) in the differentiation of olfactory neuroblastomas (ONBs) from squamous cell carcinomas (SCCs).

Standard diffusion-weighted, diffusion kurtosis and intravoxel incoherent motion MR imaging of sinonasal malignancies: correlations with Ki-67 proliferation status

ObjectivesTo explore the correlations of parameters derived from standard diffusion-weighted imaging (DWI), diffusion kurtosis imaging (DKI) and intravoxel incoherent motion (IVIM) with the Ki-67 proliferation status.MethodsSeventy-five patients with histologically proven sinonasal malignancies who underwent standard DWI, DKI and IVIM were retrospectively reviewed. The mean, minimum, maximum and whole standard DWI [apparent diffusion coefficient (ADC)], DKI [diffusion kurtosis (K) and diffusion coefficient (Dk)] and IVIM [pure diffusion coefficient (D), pseudo-diffusion coefficient (D*) and perfusion fraction (f)] parameters were measured and correlated with the Ki-67 labelling index (LI). The Ki-67 LI was categorised as high (> 50%) or low (≤ 50%).ResultsThe K and f values were positively correlated with the Ki-67 LI (rho = 0.295~0.532), whereas the ADC, Dk and D values were negatively correlated with the Ki-67 LI (rho = -0.443~-0.277). The ADC, Dk and D values were lower, whereas the K value was higher in sinonasal malignancies with a high Ki-67 LI than in those in a low Ki-67 LI (all p < 0.05). A higher maximum K value (Kmax > 0.977) independently predicted a high Ki-67 status [odds ratio (OR) = 7.614; 95% confidence interval (CI) = 2.197-38.674; p = 0.017].ConclusionADC, Dk, K, D and f are correlated with Ki-67 LI. Kmax is the strongest independent factor for predicting Ki-67 status.Key Points• DWI-derived parameters from different models are capable of providing different pathophysiological information.• DWI, DKI and IVIM parameters are associated with Ki-67 proliferation status.• Kmaxderived from DKI is the strongest independent factor for the prediction of Ki-67 proliferation status.

Changes in DTI parameters in the optic tracts of macaque monkeys with monocular blindness

For humans and non-human primates, the alteration of the visual pathways white matter fibers after visual deprivation has been partially explored. However, the changes in the optic tracts after the transection of the optic nerve have not been well characterized. In the current study, we attempted to investigate the differences in optic tracts between normal and unilateral optic nerve transected macaque monkeys using diffusion tensor imaging (DTI). Four healthy neonatal macaque monkeys were randomly divided into 2 groups, with 2 in each group. Group A served as a control group, and Group B underwent unilateral (right eye) optic nerve transection to produce monocular blindness. Sixteen months (Group B16M) and thirty-two months (Group B32M) after optic nerve transection, diffusion tensor imaging was performed on all monkeys. Then, we compared fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD) in bilateral optic tracts between Group A and Group B and between Group B16M and Group B32M. In both Group B16M and Group B32M, when compared with normal monkeys in Group A, FA was decreased and MD, AD and RD were increased in the bilateral optic tracts of monkeys with monocular blindness. Furthermore, compared with Group B16M, FA was reduced and MD, AD, RD were more obviously increased in the bilateral optic tracts of Group B32M, and noticeable differences in MD, AD and RD were found between the left and right optic tracts in group B32M. We believe that the results of this study would be helpful in investigation of the histological abnormalities of the integrity damage, axonal degeneration and demyelination of optic tracts in macaque monkeys with monocular blindness by DTI parameters in noninvasively and quantitatively.

Evaluation of changes in magnetic resonance diffusion tensor imaging of the bilateral optic tract in monocular blind rats

Some studies have used diffusion tensor imaging (DTI) to investigate white matter development of the visual pathway in humans and animals after visual deprivation. However, the alterations in the bilateral optic tract after the transection of unilateral optic nerve have not been well explored. In this study, we attempted to investigate the structural integrity of and pathological changes to the bilateral optic tract after transection of the unilateral optic nerve in rats using DTI. Eight healthy male Sprague‐Dawley (SD) rats were randomly divided into 2 groups, with 4 in each group. Group A served as a control group. Transection of the unilateral (right) optic nerve was performed in the four rats in group B at seven days after birth to establish the early monocular blind model. Four months after the operation, MnCl2 was injected into the left eyes of all rats, and MRI examinations were performed 24 h after injection. We detect the fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) values of the bilateral optic tract in all rats. In a comparison of the ipsilateral optic tract of group B with group A, a significant decrease in FA (P < 0.001) and an increase in RD (P < 0.01) of the left optic tract were found in group B, while no significant difference was found in the right optic tract. In group B, the FA and RD values of the left optic tract were significantly lower (P < 0.01) and significantly higher (P < 0.05), respectively, than those of the right optic tract. Consequently, transection of the right optic nerve can lead to structural integrity damage of and pathological changes to the left optic tract in rats. Some DTI‐derived parameters (such as FA and RD) may serve as biomarkers of optic tract degeneration.

Manganese-enhanced MR imaging (MEMRI) combined with electrophysiology in the study of cross-modal plasticity in binocularly blind rats

Our study aimed to determine and verify the establishment of visual to auditory cross‐modal plasticity using manganese‐enhanced MR imaging (MEMRI) combined with examinations of the visual evoked potential (VEP), auditory brainstem response (ABR) and bilateral visual cortex response to a bilateral auditory stimulus (AVR). Fourteen healthy male Sprague‐Dawley newborn rats were randomly divided into 2 groups (n = 7 per group). Optic nerve transection was performed in the 7 rats of Group A three weeks after birth to obtain binocularly blind models, and the 7 rats of Group B were maintained as the control group. The VEP was measured to ensure complete binocular blindness. Four months after the operation, MnCl2 was injected into the left inner ear perilymph of all rats, and an MRI examination was performed 24 h after injection. Then, ABR and AVR were measured to detect the generation of auditory compensatory function. The results of the VEP have confirmed complete binocular blindness. The normalized signal intensity of the bilateral medial geniculate nucleus, auditory cortex, visual center (including the lateral geniculate nucleus, superior colliculus and visual cortex) and right hippocampus in binocularly blind rats was significantly increased compared with that in normal rats (P ≤ 0.005), which was confirmed by measurement of the ABR and AVR. Our results suggested that MEMRI combined with electrophysiology can show changes in the auditory and visual pathways of binocularly blind rats and demonstrate the generation of an auditory compensatory pathway.

Manganese-enhanced magnetic resonance imaging combined with electrophysiology in the evaluation of visual pathway in experimental rat models with monocular blindness

Our study aimed to explore the feasibility of manganese‐enhanced magnetic resonance imaging (MEMRI) combined with visual evoked potentials (VEP) and auditory evoked visual cortex responses (AVR) in evaluating for the establishment of visual/auditory compensatory pathways after monocular blindness.