ABSTRACT
Objective To study the characteristics of MR imaging and proton MR spectrscopy(~1H MRS)of stroke-like lesions in MELAS.Methods Clinical,MR imaging and proton spectroscopic findings of stroke-like lesions in 7 patients with confirmed MELAS were analyzed retrospectively.Results A total of 12 MR investigations had been performed in 7 patients.Stroke-like lesions showed by MR imaging included superacute in 12,acute in 12,subacute in 10 and chronic stage in 6.Early stroke-like lesions were demonstrated as focal edematous foci mainly involved cortex/subcotical areas of occipital,temporal and parietal lobes.At MR diffusion imaging,stroke-like lesions in the superacute(＜3 days)stage were showed as well-circumscribed lesions with high signal intensities for cytotoxic edema.During the acute(4～7 days),sub-acute(2～4 weeks)and chronic(＞4 weeks)stages,the lesions gradually expanded,and became blur,and presented with vasogenic edema mainly.Proton spectroscopy showed a prominently elevated lactate,varied decrease of NAA concentration and other brain motabolites in the stroke-like lesions early after onset,and depicted gradual decrease of lactate level and partial recovery of NAA concentration subsequently.Conclusion Stroke-like lesions in MELAS mainly involve the cerebral cortex and subcortical areas,in which cytotoxic edema appears early but for a short period.In ~1H MRS,the lesions are characterized by a double lactate peak with decrease of NAA concentration.
ABSTRACT
Objective To analyze the MRI manifestations of meningeal carcinomatosis, and to investigate the value of MRI in diagnosis of meningeal carcinomatosis.Methods The MRI data of 28 cases with proven meningeal carcinomatosis were reviewed retrospectively.Results 11, 8 and 25 cases were detected respectively on pre-contrast T 2WI and T 1WI of SE sequence , and post-contrast T 1WI.According to the manifestations of post-contrast MRI, meningeal carcinomatosis were divided into two types: dura-arachnoid enhancement(7 cases) and pia-subarachnoid space enhancement(18 cases) in accordance with the standard of Meltzer.Conclusion MRI, especially the post-contrast MRI is a reliable modality in diagnosis of meningeal carcinomatosis. Double dosage of contrast medium and thin slice thickness can provide more informations.