Correlation between CT and diffusion-weighted imaging of acute cerebral ischemia in a rat model

Neuroimage-Based Consciousness Evaluation of Patients with Secondary Doubtful Hydrocephalus Before and After Lumbar Drainage

Hydrocephalus is often treated with a cerebrospinal fluid shunt (CFS) for excessive amounts of cerebrospinal fluid in the brain. However, it is very difficult to distinguish whether the ventricular enlargement is due to hydrocephalus or other causes, such as brain atrophy after brain damage and surgery. The non-trivial evaluation of the consciousness level, along with a continuous drainage test of the lumbar cistern is thus clinically important before the decision for CFS is made. We studied 32 secondary mild hydrocephalus patients with different consciousness levels, who received T1 and diffusion tensor imaging magnetic resonance scans before and after lumbar cerebrospinal fluid drainage. We applied a novel machine-learning method to find the most discriminative features from the multi-modal neuroimages. Then, we built a regression model to regress the JFK Coma Recovery Scale-Revised (CRS-R) scores to quantify the level of consciousness. The experimental results showed that our method not only approximated the CRS-R scores but also tracked the temporal changes in individual patients. The regression model has high potential for the evaluation of consciousness in clinical practice.

Identification of hyperacute ischemic stroke with a more homogenous nature

Previous reports revealed that middle cerebral artery occlusion (MCAO) models in rats were very diverse in nature, and experimental stroke of a more homogenous nature had not been previously documented. This paper aims to present our novel observations of experimental stroke in rats with similar MRI characteristics after MCAO. Immediately after MCAO, 19 rats were placed into a 4.7 T MRI scanner, and diffusion weighted imaging (DWI) of axial and coronal planes was repeated every 10 minutes up to post-occlusion 115 minutes. Apparent diffusion coefficient (ADC) values of the ischemic lesions were calculated and compared to those of the unaffected contra-lateral hemispheres. Successful MCAO was defined when the whole left MCA territory showed ADC abnormality on DWI. Percentage of hemispheric lesion volume (% HLV), relative ADC value (rADC), and relative DWI signal intensity (rDWI) were serially evaluated for quantitative analysis of ADC-derived lesion characteristics. Successful MCA territorial infarction was induced in nine rats (9/19, 47.4%). In quantitative analysis of ADC-derived lesion characteristics, lesion volumes of seven rats (group 1) were very similar, but larger than those of the other two rats (group 2): % HLV of initial MRI = 45.4 ± 2.5 / 19.1 ± 6.6. rADCs and rDWIs of group 1 showed similar patterns of temporal change, which was different from those of group 2. Using prospective diffusion MRI after MCAO in rats, we identified territorial hyperacute ischemic lesions with similar MRI characteristics. This observation would contribute to the establishment of more homogenous rodent models for ischemic stroke translational research.

A promising method of enhancement for early detection of ischemic stroke

BACKGROUND

Computed Tomography (CT) scan without contrast is the modality of choice for diagnosis of stroke. However, routine brain CT scan, with linear processing has some limitations in early diagnosis of ischemic stroke. The aim of this study was to evaluate and compare the sensitivity and specificity of processed CT images with conventional ones in early diagnosis of cerebrovascular attack (CVA).

PATIENTS AND METHODS

This was a self-controlled study conducted in a university referal hospital from 2010 to 2011. Seventy CT scans underwent a process using Laplacian Pyramid transform. Thirty five of participants were diagnosed with CVA while others had only headache and no ischemic stroke diagnosis based on the first and follow-up CT scans. A neuroradiologist made diagnosis with and without the help of processed CT scans. The McNemar and Wilcoxon analysis were used to compare the sensitivity, specificity, positive and negative predictive values of two methods.

RESULTS

The sensitivity (% 65.7 vs. %31.4, P value = 0.001), positive predictive value (% 85.2 vs. % 61, P value = 0.03) and negative predictive value (% 73.9% vs. %49, P value = 0.01) of the processed method were significantly higher than the routine one, while no difference was seen in specificity (% 88.6 vs. %77.1, P value = 0.15). Moreover, the accuracy of the processed method was significantly better than the linear one (P value < 0.001).

CONCLUSIONS

It was concluded that nonlinear modified Laplacian Pyramid method can composed CT scans which can be more helpful in early detection of ischemic stroke.