Diffusion tensor imaging of normal-appearing white matter in unilateral cerebral arterial occlusive disease.

PURPOSE: To use MR with diffusion tensor imaging (DTI) and conventional and high b value to assess diffusion changes in normal-appearing white matter (NAWM) in patients with unilateral, severe stenosis, or occlusion of the middle cerebral artery (MCA). MATERIALS AND METHODS: In total, 28 patients with NAWM and unilateral, severe stenosis, or occlusion of the MCA underwent DTI with b values 1000 and 2200 s/mm(2) at 3.0T MR. Fractional anisotropy (FA), apparent diffusion coefficient (ADC), radial diffusivity (eigenvalues λ1 , λ2 ), and axial diffusivity (eigenvalue λ3 ) were measured for the ipsilateral and contralateral corona radiata. RESULTS: Mean FA was significantly lower for the ipsilateral than contralateral corona radiata with high b value, 2200 s/mm(2) , and ipsilateral corona radiata with conventional low b value, 1000 s/mm(2) (all P < 0.01). Mean ADC, λ1 , λ2 , and λ3 were significantly higher for the ipsilateral than contralateral corona radiata with high b value (all P < 0.05) but not for ipsilateral than contralateral corona radiata with low b value (P > 0.05). CONCLUSION: DTI with a high b value detects diffusion changes in NAWM in patients with unilateral, severe stenosis, or occlusion of the MCA not seen with conventional b value or conventional MRI contrasts.

[Evaluation of blood oxygen level in hepatocellular carcinoma with noninvasive magnetic resonance multi-echo R2* technique and its clinical significance].

OBJECTIVE: To probe the relationship of clinical and pathological features of hepatocellular carcinoma (HCC) with the blood oxygen level by the technique of noninvasive magnetic resonance multi-echo R2*. METHODS: Multi-echo R2* sequence was carried out pre-operatively in a total of 46 patients with pathologically proved HCC. The T2* and R2* values of HCC, liver, spleen and paraspinous muscle on T2* and R2* maps and the ratios of HCC to liver (H/L), spleen (H/S) and muscle (H/M) were calculated. Different groups were defined according to such clinical parameters as the serum AFP level, lesion dimension, Edmondson's grade, ascites, capsula, liver cirrhosis, intrahepatic daughter foci or tumor-emboli in portal vein respectively. The differences in T2* and R2* values and the ratios between different groups were analyzed. RESULTS: In contrast with T2* value, the R2* value of HCC was less than that of liver or spleen (P < 0.05). Difference in R2* ratio of H/M (0.81 +/- 0.26 vs. 1.23 +/- 0.39) was found between positive and negative groups of AFP (P = 0.047, t = 2.248). And so was the same difference (0.83 +/- 0.24 vs. 1.23 +/- 0.43) between the lesions with or without capsula (P = 0.046, t = 2.257). The R2* ratio of H/S in hepatic cirrhosis group (1.01 +/- 0.58) was higher than that in noncirrhosis one (0.53 +/- 0.17) (P = 0.035, t = 2.247) whereas the T2* ratio of H/S was reversed (1.42 +/- 0.92 vs. 2.64 +/- 1.15) (P = 0.036, t = 2.230). The differences in T2* ratio of H/M in the group with or without intrahepatic daughter foci (1.18 +/- 0.47 vs. 2.24 +/- 1.71) (P = 0.048, t = 2.115), and in T2* value in the group with or without tumor-emboli in portal vein (27.24 +/- 11.90 ms vs. 46.70 +/- 38.40 ms) (P = 0.049, t = 2.046) were shown to be significant. However, no differences in MR parameters between other groups were observed (P > 0.05). CONCLUSION: The blood oxygen level parameters, R2* and T2* values and the ratios are related to some clinical and pathological features of HCC. And the blood oxygen level is affected by multiple factors.

Sectional anatomy of the peritoneal reflections of the upper abdomen in the coronal plane.

PURPOSE: The purpose of this study was to provide practical anatomic data for the imaging diagnosis and surgical treatment of the diseases of the subphrenic spaces. METHODS: The sectional anatomy of the subphrenic spaces on the coronal plane was investigated on serial coronal sections of the upper abdomen of 30 Chinese adult cadavers. RESULTS: The space between the anterior margin of gastropancreatic fold and the posterior layer of hepatogastric ligament is the only direct pathway between the superior and inferior recesses of the lesser sac. That pathway can be divided into 3 types on the coronal plane. The right layer of the gastrophrenic ligament is continuous with the posterior layer of the lesser omentum, and its left layer is continuous with the right layer of the phrenosplenic ligament and the posterior layer of the gastrosplenic ligament. The gastropancreatic fold is continued to the left and right layers of the gastrophrenic ligament upwards. The bare area of the stomach is located between the left and right layers of the gastrophrenic ligament; its existing rate is 100%. The bare area of the spleen is located among the phrenosplenic ligament, gastrosplenic ligament, splenorenal ligament, and splenocolic ligament. Its greatest width exists between the two layers of the splenorenal ligament. It can be divided into the splenic hilus and splenorenal parts. CONCLUSION: The coronal section is dominant to show the anatomic relationships of the gastrophrenic ligaments and the gastropancreatic folds, and the bare area of the stomach.

Lie detection by functional magnetic resonance imaging.

The accurate detection of deception or lying is a challenge to experts in many scientific disciplines. To investigate if specific cerebral activation characterized feigned memory impairment, six healthy male volunteers underwent functional magnetic resonance imaging with a block-design paradigm while they performed forced-choice memory tasks involving both simulated malingering and under normal control conditions. Malingering that demonstrated the existence and involvement of a prefrontal-parietal-sub-cortical circuit with feigned memory impairment produced distinct patterns of neural activation. Because astute liars feign memory impairment successfully in testing once they understand the design of the measure being employed, our study represents an extremely significant preliminary step towards the development of valid and sensitive methods for the detection of deception.