Glioma grading by microvascular permeability parameters derived from dynamic contrast-enhanced MRI and intratumoral susceptibility signal on susceptibility weighted imaging.

BACKGROUND: Dynamic contrast-enhanced MRI (DCE-MRI) estimates vascular permeability of brain tumors, and susceptibility-weighted imaging (SWI) may demonstrate tumor vascularity by intratumoral susceptibility signals (ITSS). This study assessed volume transfer constant (Ktrans) accuracy, the volume of extravascular extracellular space (EES) per unit volume of tissue (Ve) derived from DCE-MRI, and the degree of ITSS in glioma grading. METHODS: Thirty-two patients with different glioma grades were enrolled in this retrospective study. Patients underwent DCE-MRI and non-contrast enhanced SWI by three-tesla scanning. Ktrans values, Ve, and the degree of ITSS in glioma were compared. Receiver operating characteristic (ROC) curve analysis determined diagnostic performances of Ktrans and Ve in glioma grading, and Spearman's correlation analysis determined the associations between Ktrans, Ve, ITSS, and tumor grade. RESULTS: Ktrans and Ve values were significantly different between low grade gliomas (LGGs) and both high grade gliomas (HGGs) and grade II, III and IV gliomas (P<0.01). The degree of ITSS of LGGs was lower than HGGs (P<0.01), and the ITSS of grade II gliomas was lower than grade III or IV gliomas. Ktrans and Ve were correlated with glioma grade (P<0.01), while ITSS was moderately correlated (P<0.01). Ktrans values were moderately correlated with ITSS in the same segments (P<0.01). CONCLUSION: Ktrans and Ve values, and ITSS helped distinguish the differences between LGGs and HGGs and between grade II, III and IV gliomas. There was a moderate correlation between Ktrans and ITSS in the same tumor segments.

White matter integrity and cognition in mild traumatic brain injury following motor vehicle accident.

The aim of this study is to explore the white matter structure integrity in patients with mild traumatic brain injury (mTBI) using diffusion tensor imaging (DTI), and to analyze the relationship between the white matter structure integrity and cognitive impairment of patients with mTBI. Twenty-five patients with mTBI and 25 healthy control subjects were studied with conventional MR imaging and diffusion tensor imaging. Fractional anisotropy (FA) and mean diffusivity (MD) maps of patients with mTBI were calculated and compared, with these control maps using tract-based spatial statistics (TBSS). Significantly lower fractional anisotropy was found in patients in the uncinate fasciculus, superior longitudinal fasciculus, inferior longitudinal fasciculus, and internal capsule. Mean diffusivity was significantly elevated in the body of corpus callosum, uncinate fasciculus, superior longitudinal fasciculus, and internal capsule in the mTBI group compared with the control group (P<0.05). The mTBI group showed a significant negative correlation between the elevated mean diffusivity of the uncinate fasciculus and the working memory index (WMI) (R(2)=0.51, P<0.05), and the internal capsule of MD values was significantly negatively related to processing speed index (PSI) (R(2)=0.45, P<0.05). There was a positive correlation between the FA value of the uncinate fasciculus and Mini Mental State Examination (MMSE) in the mTBI patient group (R(2)=0.36, P<0.05). TBSS analysis of DTI suggests that patients with mTBI have focal axonal injury, and the pathophysiology is significantly related to the MMSE and IQ of mTBI patients. Diffusion tensor imaging can be a powerful technique for in vivo detection of mTBI, and can help in the diagnosis of patients with mTBI.

Diffusion tensor imaging and magnetic resonance spectroscopy in traumatic brain injury: a review of recent literature.

Concussion is the most common form of traumatic brain injury (TBI), but diagnosis remains controversial because the brain appears quite normal in conventional computed tomography and magnetic resonance imaging (MRI). These conventional tools are not sensitive enough to detect diffuse traumatic axonal injury, and cannot depict aberrations in mild TBIs. Advanced MRI modalities including diffusion tensor imaging (DTI), and magnetic resonance spectroscopy (MRS), make it possible to detect brain injuries in TBI. The purpose of this review is to provide the latest information regarding the visualization and quantification of important abnormalities in TBI and new insights into their clinical significance. Advanced imaging modalities allow the discovery of biomarkers of injury and the detection of changes in brain injury over time. Such tools will likely be used to evaluate treatment efficacy in research. Combining multiple imaging modalities would not only provide greater insight into the underlying physiological changes in TBI, but also improve diagnostic accuracy in predicting outcomes. In this review we present evidence of brain abnormalities in TBI based on investigations using MRI, including DTI and MRS. Our review provides a summary of some of the important studies published from 2002 to 2012 on the topic of MRI findings in head trauma. With the growing realization that even mild head injury can lead to neurocognitive deficits, medical imaging has assumed preeminence for detecting abnormalities associated with TBI. Advanced MRI modalities such as DTI and MRS have an important role in the diagnosis of lesions for TBI patients.