Optimal Factors of Diffusion Tensor Imaging Predicting Corticospinal Tract Injury in Patients with Brain Tumors

OBJECTIVE: To identify the optimal factors in diffusion tensor imaging for predicting corticospinal tract (CST) injury caused by brain tumors. MATERIALS AND METHODS: This prospective study included 33 patients with motor weakness and 64 patients with normal motor function. The movement of the CST, minimum distance between the CST and the tumor, and relative fractional anisotropy (rFA) of the CST on diffusion tensor imaging, were compared between patients with motor weakness and normal function. Logistic regression analysis was used to obtain the optimal factor predicting motor weakness. RESULTS: In patients with motor weakness, the displacement (8.44 ± 6.64 mm) of the CST (p = 0.009), minimum distance (3.98 ± 7.49 mm) between the CST and tumor (p < 0.001), and rFA (0.83 ± 0.11) of the CST (p < 0.001) were significantly different from those of the normal group (4.64 ± 6.65 mm, 14.87 ± 12.04 mm, and 0.98 ± 0.05, respectively) (p = 0.009, p < 0.001, and p < 0.001). The frequencies of patients with the CST passing through the tumor (6%, p = 0.002), CST close to the tumor (23%, p < 0.001), CST close to a malignant tumor (high grade glioma, metastasis, or lymphoma) (19%, p < 0.001), and CST passing through infiltrating edema (19%, p < 0.001) in the motor weakness group, were significantly different from those of the patients with normal motor function (0, 8, 1, and 10%, respectively). Logistic regression analysis showed that decreased rFA and CST close to a malignant tumor were effective variables related to motor weakness. CONCLUSION: Decreased fractional anisotropy, combined with closeness of a malignant tumor to the CST, is the optimal factor in predicting CST injury caused by a brain tumor.

Does diffusion tensor tractography of the corticospinal tract correctly reflect motor function?

To investigate the consistency of diffusion tensor tractography of the corticospinal tract on motor function. Clinical Presentations and Intervention: Three patients with brain tumor were admitted to our hospital with impaired motor function. Diffusion tensor imaging [DTI] and tractography were performed in these patients to assess their affected corticospinal tract. The corticospinal tract showed interruption with moderately impaired motor function in 2 patients. The third case had significantly weakened muscle strength on the left upper limb but an intact right corticospinal tract. These cases showed that the corticospinal tracts obtained by DTI with tractography were inconsistent with motor function. Hence, DTI should be interpreted with caution

Association of Helicobacter pylori with Elevated Blood Ammonia Levels in Cirrhotic Patients: A Meta-Analysis

PURPOSE: The association between Helicobacter pylori (H. pylori) and blood ammonia levels in cirrhotic patients is controversial. We aimed to clarify this controvercy by performing a meta-analysis of published studies. MATERIALS AND METHODS: We searched PubMed, EMBASE and Cochrane library for studies which explored the association between H. pylori and blood ammonia levels in cirrhotic patients before May 2012. Six cohort studies involved in 632 H. pylori positive and 396 H. pylori negative cirrhotic patients were eligible for our analysis. The summary estimates were presented as standard means differences (SMD) and 95% confidence intervals (CI) from individual studies. RESULTS: Overall, there was significant association between H. pylori infection and the elevated blood ammonia levels in cirrhotic patients (SMD=0.34, 95% CI=0.21-0.47, I2=42.1%). Sensitivity analysis further confirmed this association. Subgroup analysis showed that the association was found only in Asian ethnicity, but not in Caucasian ethnicity. CONCLUSION: H. pylori infection is associated with elevated blood ammonia levels in cirrhotic patients, and more large scale studies and stratify analysis are warranted in order to further evaluate this association.