Optic radiation in normal adults: a study using magnetic resonance diffusion tensor imaging and diffusion tensor tractography / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the fractional anisotropy (FA) and the architecture of the optic radiation fiber tracts of normal adults with magnetic resonance (MR) diffusion tensor imaging (DTI).</p><p><b>METHODS</b>Diffusion tensor images were obtained from 30 healthy volunteers without any cerebral abnormalities on conventional MRI. FA and the mean diffusivity (MD) of the optic radiation were measured in the directional encoded color (DEC) maps. The architecture of the optic radiation fiber tracts were displayed with the software of diffusion tensor fiber tracking.</p><p><b>RESULTS</b>In all subjects, the optic radiation could be readily identified in the DEC maps. The FA value was 0.509-/+0.029 in the left and 0.502-/+0.026 in the right, with the MD value of (0.763-/+0.050) x10(-3) and 0.748-/+0.052)x10(-3) mm2/s, respectively. No significant differences were found in the FA or MD value of the bilateral optic radiation (P>0.05). Diffusion tensor tractography (DTT) demonstrated that the 3 bundles of the optic radiation fibers were located in the lateral sagittal stratum, passing from the lateral geniculate body of the thalamus to the primary visual cortex. The dorsal and lateral bundles passed posteriorly to the superior bank of the calcarine cortex, while the ventral bundle passed anteriorly before making a sharp turn, known as the Meyer loop, and subsequently coursed posteriorly to terminate in the inferior margin of the calcarine cortex, which was consistent with the results of classic anatomical studies.</p><p><b>CONCLUSION</b>As a novel method to study the relationship between visual function and optic pathway, DTI and DTT can show the FA and architecture of the optic radiation.</p>

Using 1H-MRS to evaluate the effects of warm ischemia reperfusion injury on the regeneration of hepatic cells in orthotopic transplanted livers in rats / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To investigate the prognostic value of proton magnetic resonance spectroscopy (1H-MRS) in the study of warm ischemia reperfusion injury to the regeneration of hepatic cells of the livers following their orthotopic transplantation in rats.</p><p><b>METHODS</b>A rat orthotopic liver transplantation (OLT) model with warm ischemia, the experimental group, was established and the same was done with a control group but without warm ischemia of the livers. They were studied at 6 time points (6 hours, 1, 3, 7, 14, and 30 days after OLT). All rats took axial T1 weighted and T2 weighted imaging scans and 1H MR spectroscopies.</p><p><b>RESULTS</b>The positive rate of proliferating cell nuclear antigen (PCNA) and the mean peak choline/water ratio in the experimental group were significantly higher than those in the control group and the peak choline /water ratio had a positive correlation with the positive rate of PCNA. Serum ALT and AST increased significantly after OLT, especially during the 6 hour to 3day period. The levels of ALT and AST were markedly higher in the experimental group compared to the control group.</p><p><b>CONCLUSION</b>Warm ischemia reperfusion injury of OLT has a significant effect on the regeneration of hepatic cells, and the choline peak of 1H-MRS can be used to evaluate the regeneration of hepatic cells non-invasively.</p>

Quantitative study of dynamic magnetic resonance perfusion-weighted imaging in rabbit models of implanted hepatic VX2 tumor / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the possibility of dynamic magnetic resonance (MR) perfusion-weighted imaging (PWI) in rabbit models of implanted hepatic VX2 tumor.</p><p><b>METHODS</b>MRI and PWI images were obtained from 16 rabbit models of implanted hepatic VX2 tumor and 4 normal rabbits at 14, 18, 22, and 26 days after tumor implantation, respectively, and the mean time to enhancement (MTE) and maximum slope of increase (MSI) were estimated and compared with pathological changes.</p><p><b>RESULTS</b>In the rabbit models of implanted hepatic tumor the MTE tended to increase and MSI to descend 14, 18, 22, and 26 days after tumor implantation, showing significant differences from the control group. Coagulation necrosis and fibrous hyperplasia in the tumors appeared to progress with time as found pathologically.</p><p><b>CONCLUSION</b>Dynamic MR PWI quantitative analysis of rabbit models of implanted hepatic VX2 tumor provides valuable means for observing the growth behaviors of VX2 tumor and may be clinically applicable in the evaluation of hepatic diseases.</p>