Keywords:
Neuroradiology brain, Neuroradiology peripheral nerve, Neuroradiology spine
Authors:
E. Kim, S.-T. Kim, D. H. Lee; Seoul/KR
DOI:
10.1594/ecr2010/C-2708
Methods and Materials
Patients
From December 2006 to Mar 2009, we prospectively collected MR images that showed accentuated gray-white differentiation on the ADC maps, and especially those ADC maps of those patients with hypoxic brain injury, brain death, hypoglycemia, status epilepticus and other toxic or metabolic encephalopathies and who were seen during our routine clinical practice. There were 19 patients (9 males and 10 females) with 20 MR images and their DWI or ADC maps showed pronounced gray-white differentiation. Their age ranged from 37 to 82 years (mean age: 53 years). The medical records of all 19 patients were retrospectively reviewed to evaluate their medical and neurologic statuses and the final clinical outcomes. Age-mated controls (n=10) whose brain MR demonstrated findings within the normal limits were included for comparison. Consent for MR imaging was obtained from a legally authorized representative, yet consent for this imaging study was waived. Our institutional review board approved this retrospective study.
MR images
The diffusion-weighted images were obtained using 1.5T or 3 T MR imaging systems (Signa Excite, GE Medical Systems, Milwaukee, WI; Sonata, Siemens, Erlangen, Germany) in all the patients. The DWI was obtained with a single-shot spin-echo echo-planar pulse sequence with two diffusion sensitivity values of 0 and 1000 s/mm2 along all three orthogonal axes. The slice thickness and gap of the DWI was 3mm and 1 mm, respectively. Other brain MR images that included the spin-echo T1-weighted, fast spin-echo T2-weighted and fast fluid-attenuated inversion-recovery (FLAIR) images were obtained for nine patients. The MR imaging parameters were as follows: 450–466/12/2 (TR/TE/NEX) for the spin-echo T1-weighted images, 3666–4000/96–104/1–2/7 (TR/TEeff/NEX/echo train) for the fast spin-echo T2-weighted images and 5000–10000/110–155/2000/1/7 (TR/TEeff/TI/NEX/echo train) for the FLAIR images. MR angiography of the intracranial vessels was done with using the 3D time-of-flight (TOF) technique in eight patients. The contrast-enhanced MRA (n=3) or 3D TOF (n=5) images for the carotid vessel were also obtained.
Image and statistical analysis
We retrospectively evaluated the brain MR images, and if there were different patterns of the DWI and ADC maps for these patients with global brain injury. To quantitatively determine these patterns, we measured the ADC values at representative areas of the brain. Fifteen ROIs for each patient were obtained with manual drawing on the ADC map for assessing lesions in the following areas: the bilateral frontal cortexes and deep white mater (WM) at the level of the centrum semiovale (n=4), the bilateral frontal cortical and periventricular WM at the level of the lateral ventricle (n=4), the bilateral putamens in the basal ganglia (n=2), the bilateral thalami (n=2) and the bilateral cerebellar hemispheres at the levels of both the middle cerebral peduncle (n=2) and the mid portion of the splenium (n=1). The ADC values of the control subjects were also measured at the above mentioned areas of the brain.
All patients with global brain injury were divided into three groups based on the ADC decrease of the cerebral cortical and WM. The mean ADC values at all measured anatomical locations were statistically analyzed for each group and a control group. One way analysis of variance (ANOVA) was used to compare the mean values of the ADC at the each anatomic location of the three groups of patients and a control group, and the Turkey test was used for multiple comparisons.