Evaluation of mannitol effect in patients with acute hepatic failure and acute-on-chronic liver failure using conventional MRI,diffusion tensor imaging and in-vivo proton MR spectroscopy

AIM： To evaluate the effect of an intravenous bolus of mannitol in altering brain metabolites, brain water content, brain parenchyma volume, cerebrospinal fluid （CSF） volume and clinical signs in controls and in patients with acute liver failure （ALF） and acute- on-chronic liver failure （ACLF）, by comparing changes in conventional magnetic resonance imaging （MRI）, in vivo proton magnetic resonance spectroscopy （PMRS） and diffusion tensor imaging （DTI） before and after its infusion.METHODS： Five patients each with ALF and ACLF in grade 3 or 4 hepatic encephalopathy and with clinical signs of raised intracranial pressure were studied along with five healthy volunteers. After baseline MRI, an intravenous bolus of 20% mannitol solution was given over 10 min in controls as well as in patients with ALF and ACLE Repeat MRI for the same position was acquired 30 rnin after completing the rnannitol injection. RESULTS： No statistically significant difference was observed between controls and patients with ALF and ACLF in metabolite ratios, DTI metrics and brain volume or CSF volume following 45 rain of mannitol infusion. There was no change in clinical status at the end of post-mannitol imaging. CONCLUSION： The osmotic effect of mannitol did not result in significant reduction of brain water content, alteration in metabolite ratios or any change in the clinical status of these patients during or within 45 min of mannitol infusion.

Application of proton MR spectroscopy on evaluation of radiotherapy treated intracranial tumors

Objective： To evaluate the clinical application of proton magnetic resonance spectroscopy （1HMRS） in patients with radiotherapy treated intracranial tumors. Methods： Forty patients with intracranial tumors underwent multivoxel 1HMRS examination before and after radiotherapy. The concentrations of N-acetyl aspartate （NAA）, choline （Cho） and creatine （Cr） were obtained both in the tumors and the contralateral normal brain regions, The ratios of NANCr, Cho/Cr and Cho/NAA were calculated at the same time and follow-up one year. Results： （1） After radiotherapy, tumors inhibited by radiation had decreased Cho, NAA and Cr on proton MRS. Some cases showed necrotic wave. （2） During the one year follow-up, local tumor recurred in 8 cases and their Cho and Cho/NAA increased high again. Other cases without recurrence, HMRS showed no change. Conclusion： Multivoxel proton MR spectroscopy is available for study of tumor metabolites after radiotherapy and it is a valuable method in the evaluation of radiotherapy treated tumors,