Purpose:To evaluate the feasibility of single voxel 1H-MRS of the CNS structures contained in the posterior cranial fossa and to determine the distribution of the normal metabolite ratios, concentrations, and T2 relaxation times in the midbrain, pons, medulla, dentate nucleus and cerebellar vermis. Materials and Methods:A total of 147 single voxel 1H-MR spectra with a point-resolved proton spectroscopy sequence (PRESS) sequence and echo time (TE) of 136 or 272 msec were obtained in the midbrain, pons, medulla, dentate, and vermis of 31 healthy volunteers. In seven additional patients; the concentrations and T2 relaxation times of metabolites were obtained in the same locations (except the medulla) with an external phantom calibration method and a four TE PRESS technique.Results: Ten (27%) of 36 spectra acquired in the medulla were of poor quality. A similar ranking of the N-acetyl aspartate (NAA)/creatine (Cr) ratio and choline(Cho)/Cr ratios in the five locations for the two TEs was observed, with the highest values in the pons (mean NAA/Cr ϭ 4.16 Ϯ 0.6 and Cho/Cr ϭ2.66 Ϯ 0.6 at TE 272) and the lowest values in the dentate and vermis (mean NAA/Cr ϭ 1.66 Ϯ 0.2 and Cho/Cr ϭ 1.20 Ϯ 0.2 at TE 272). The analysis of variance showed significant regional differences of the NAA and Cr concentrations, which had the highest values in the dentate. Non-significant regional differences were observed for the concentration of Cho and for the T2 of the metabolites. Conclusion:With the exception of the medulla, single voxel 1H-MRS enables an in vivo biochemical analysis of the CNS structures contained in the posterior cranial fossa. Regional differences in the metabolite ratios and concentrations must be considered when employing 1H-MRS for evaluation of diseases of the brainstem and cerebellum.

CTC can be detected in two-thirds and CTM in more than half of patients with advanced NSCLC at diagnosis. Reasons underlying lack of CTC and CTM in some advanced lung cancers deserve further investigations.

Two patients are reported in whom the presence of triventricular hydrocephalus and aqueductal obstruction or stenosis due to multiple expanding lacunae in the mesencephalothalamic region possibly corresponds to abnormally dilated perivascular spaces. Placement of a ventriculoperitoneal cerebrospinal fluid (CSF) shunt in one patient and the performance of a third ventricle cisternotomy in the other reversed the hydrocephalic syndrome, but did not modify the complex neuroophthalmological disturbance and rubral tremor presumably related to the compressive effects of the lacunae on adjacent parenchyma. In one patient the number and size of the lacunae were increased 4 years after CSF shunt placement. A review of the literature revealed two cases in which magnetic resonance imaging demonstrated a similar, poorly understood pathological condition.

Hashimoto's thyroiditis, in most of whom cerebellar atrophy was shown on magnetic resonance imaging. One of their reported cases was treated by intravenous immunoglobulin IgG, and ataxia partially improved.5 Although responsiveness to intravenous immunoglobulin suggested autoimmune mechanisms in the pathogenesis of ataxia in this patient, it remains uncertain whether or not ataxia and cerebellar atrophy were aetiologically associated with Hashimoto's thyroiditis. By contrast, our patient with progressive ataxia had a positive serological diagnostic marker, anti-NAE antibodies and showed an excellent response to steroid treatment, leading to a diagnosis of Hashimoto's encephalopathy.In conclusion, this report suggests that a diagnosis of Hashimoto's encephalopathy is warranted in patients with progressive pure ataxia and anti-NAE antibodies are a useful serological marker of diagnosis. Moreover, Hashimoto's encephalopathy should be included in a differential diagnosis of a treatable ataxia.

A patient with suprasellar and brain stem involvement in Erdheim Chester disease (ECD) underwent magnetic resonance (MR) imaging and proton MR spectroscopy (1H MRS) of the ventral pons before and 1, 4 and 18 months after external whole-brain (24 Gy) radiotherapy. By revealing a decrease of the N-acetyl-aspartate/choline ratio in the pons, 1H MR spectroscopy anticipated lesions growth on MR imaging. In line with the results in four patients reported in the literature, our observation indicates that external radiation therapy is not effective for intracranial involvement in ECD.