Microstructural and Neurochemical Changes in the Rat Brain After Diffuse Axonal Injury.

BACKGROUND: Diffuse axonal injury (DAI) is one of the devastating types of traumatic brain injury, but is difficult to detect on conventional imaging in its early stages. PURPOSE: To test the technical feasibility and diagnostic value of diffusion kurtosis imaging (DKI) and glutamate chemical exchange saturation transfer (GluCEST) imaging in the brain after DAI. STUDY TYPE: Prospective. ANIMAL MODEL: Sixty Sprague-Dawley rats. The DAI model was induced by using the impact acceleration model of Marmarou et al with modified settings. FIELD STRENGTH/SEQUENCE: A 7.0T animal MR scanner with a fast spin-echo sequence (T2 -weighted imaging), fast spin-echo multislice sequence (DKI), echo planar imaging in the signal of the chemical exchange saturation transfer sequence (CEST), and point-resolved spectroscopy sequence (hydrogenproton magnetic resonance spectroscopy, 1 H-MRS). ASSESSMENT: Brain MRI scanned before and 2 hours after injury. DKI images were processed with MatLab and MRIcro software, GluCEST images were processed using software routines written in MatLab, and spectroscopic data were postprocessed with LCModel. STATISTICAL TESTS: The parameters of these techniques were assessed using the independent sample t-test and Pearson correlation. RESULTS: Mean kurtosis and mean diffusivity values were significantly higher than controls in the parietal lobe, hippocampus, and thalamus (P < 0.01). However, fractional anisotropy was lower only in the parietal lobe, with no detectable changes in the hippocampus and thalamus. GluCEST values of the parietal lobe, hippocampus, and thalamus were significantly higher than controls in DAI rats (P < 0.01). This change was further validated through 1 H-MRS. A positive correlation was observed between glutamate (Glu) and glutamate compound (Glx) concentrations and GluCEST values (Glu: R2 = 0.589, Glx: R2 = 0.878). DATA CONCLUSION: DKI and GluCEST might be acceptably sensitive for tracking microstructural and neurochemical changes in the brain following DAI. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:1069-1077.

Glutamate Chemical Exchange Saturation Transfer (GluCEST) Magnetic Resonance Imaging of Rat Brain With Acute Carbon Monoxide Poisoning.

Objectives: To evaluate the diagnostic and prognostic values of glutamate chemical exchange saturation transfer (GluCEST) magnetic resonance imaging as a quantitative method for pathogenetic research and clinical application of carbon monoxide (CO) poisoning-induced encephalopathy combined with the proton magnetic resonance spectroscopy (1H-MRS) and the related histopathological and behavioral changes. Methods: A total of 63 Sprague-Dawley rats were randomly divided into four groups. Group A (n = 12) was used for animal modeling verification; Group B (n = 15) was used for magnetic resonance molecular imaging, Group C (n = 15) was used for animal behavior experiments, and Group D (n = 21) was used for histopathological examination. All the above quantitative results were analyzed by statistics. Results: The peak value of carboxyhemoglobin saturation in the blood after modeling was 7.3-fold higher than before and lasted at least 2.5 h. The GluCEST values of the parietal lobe, hippocampus, and thalamus were significantly higher than the base values in CO poisoning rats (p < 0.05) and the 1H-MRS showed significant differences in the parietal lobe and hippocampus. In the Morris water maze tests, the average latency and distance were significantly prolonged in poisoned rats (p < 0.05), and the cumulative time was shorter and negatively correlated with GluCEST. Conclusion: The GluCEST imaging non-invasively reflects the changes of glutamate in the brain in vivo with higher sensitivity and spatial resolution than 1H-MRS. Our study implies that GluCEST imaging may be used as a new imaging method for providing a pathogenetic and prognostic assessment of CO-associated encephalopathy.

Ectopic thyroid gland located on the L4 vertebral body: A case report.

RATIONALE: The prevalence of ectopic thyroid is extremely low, with the condition observed in approximately 1 in 100,000 to 300,000 people. Thyroid gland ectopia develops as a result of the presence of developmental abnormalities during the migration of the thyroid anlage from the floor of the primitive foregut to its final position in the neck. Ectopic thyroid tissue is commonly observed in the lingual region, but can also present in other head and neck regions, as well as regions located at a large distance from the neck. PATIENT CONCERNS: A 67-year-old woman who had experienced left lumbago and leg pain was transferred to our hospital following the worsening of her lumbago-related symptoms in the 2 months preceding her presentation. Seven years ago, the patient had recurrent lumbago and leg pain without obvious inducement, and visited a local clinic for treatment. The severity of her symptoms fluctuated; their intensity increased after participation in activities and decreased after rest. DIAGNOSES: The patient was diagnosed as having an ectopic thyroid gland that was located on the L4 vertebral body. INTERVENTIONS: The patient chose to undergo surgery, with supportive care, following tumor discovery. OUTCOMES: After surgical treatment, the degree of lumbar spinal stenosis improved, and the patient's clinical symptoms were alleviated. LESSONS: Clinically, ectopic goiter is diagnosed through radionuclide thyroid imaging, ultrasound examination, computed tomography, magnetic resonance imaging, and biopsy pathology. However, the imaging manifestations in this case were atypical, leading to greater diagnostic difficulties. A conclusion was finally reached based on pathology.