MRS and diffusion tensor image in mild traumatic brain injuries

To analyze characters of magnetic resonance spectroscopy (MRS) and diffusion tensor imaging (DTI) in the diagnosis of mild trauma brain injuries (MTBI) in frontal lobe and to compare with conventional magnetic resonance imaging (MRI).

A total of 21 patients were selected, who all aged 12-51 years old and had injury within 24 hours. Computer tomography (CT) and the Glasgow Coma Scale were used to evaluate the degree of injury. All patients were diagnosed as MTBI, and 19 had conventional MRI, MRS and DTI. The major parameters of MRS were Probe-P sequence, TE = 144 or 35 ms, and both single voxel spectrum and chemical shift imging were included. The major parameters of DTI were diffusion directions =15, b value = 1 000 s/mm(2). Frational anisotropic (FA) map and average ADC map were obtained to evaluate DTI result. Positive detetion ratio was observed and the imaging changes were compared between injured side and normal side.

All 21 patients had CT scan and Glasgow scale. A total of 19 patients had conventional MRI, DTI and MRS. Results of CT and conventional MRI showed no significant abnormality in lobe, and Glasgow scale showed mild type. MRS result showed significant decrease in N-acetyl aspartate (NAA) and NAA/creatine (Cr) in 13 cases (68.4%) (P<0.001), and increase in lactic acid (Lac) in 7 cases (36.8%). FA mapping of the frontal lobe displayed significant changes in 7 cases (36.8%), with 5 out of the 7 cases having increase in FA value. And there was no significant difference in average ADC.

MRS and DTI might be more sensible than other methods, such as CT and conventional MRI in diagnosis of MTBI. The particular changes were reduced NAA and increased Lac for MRS, and increased FA values for DTI.