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Background. The aim of our study was (1) to describe central nervous system (CNS) manifestations in children with Langerhans cell histiocytosis (LCH) based on images sent to a reference center and meeting minimum requirements and (2) to assess the inter-rater agreement of CNS-MRI results, which represents the overall reproducibility of this investigation.

Purpose: Limbic encephalitis (LE) is an immune-related disease with limbic symptoms, variable and asymmetric magnetic resonance imaging (MRI) aspects and antibody profiles. This study investigated the diagnostic value of quantitative relaxation times T2 (qT2) and MRI signal intensities (SI) in LE. Methods: The prospective 3T-MRI study included 39 epilepsy patients with initially suspected LE and 20 healthy controls. Values and asymmetry indices of qT2, T2-weighted (T2-w) and proton density (PD)-w SI of manually delineated and automatically segmented amygdala and hippocampus were measured. Additionally, two raters made a blinded visual analysis on FLAIR (fluid attenuation inversion recovery) and T2-w images. Results: According to diagnostic guidelines, 22 patients had probable LE and 17 patients had possible LE. The qT2 was higher (p < 0.01) in patients than in controls (mean ± SD, amygdala 98 ± 7 ms vs. 90 ± 5 ms, hippocampus 101 ± 7 ms vs. 92 ± 3 ms), but was not different between probable and possible LE or between sides (left and right). The PD-w SI and T2-w SI were lower in patients than in controls but were not different between patient subgroups or between sides. Diagnostic performance of visual analysis was relatively poor. Conclusions: Epilepsy patients with suspected LE had elevated qT2 in amygdala and hippocampus, whereas the expected T2-w SI increase was not found; however, the diagnostic value of qT2 remains questionable since it did not discriminate probable from possible LE. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to evaluate whether patients with drug-resistant mesial temporal lobe epilepsy (TLE) due to hippocampal 'gliosis only' have different MRI features than those with hippocampal sclerosis (HS). Most TLE patients have HS corresponding to severe neuronal loss and gliosis, but a few have 'gliosis only' without significant reduction of neuronal density. Methods: We analyzed the morphology of cerebral 3 T MRIs (T1, T2, and FLAIR) of 103 patients with HS and 20 with 'gliosis only' concerning hippocampal and amygdala aspect, volumes, and signal intensity (SI) using Fisher's exact test, Student's t test, and principal component analysis. Results: Visually, the ipsilateral hippocampus was hyperintense in both groups, but SI was markedly increased in 74% of HS and in 25% of 'gliosis only' patients; the ipsilateral hippocampus was smaller in 92% of HS and in 50% of 'gliosis only' patients, and its internal architecture was lost in 57% of HS and 5% of 'gliosis only' patients; the contralateral hippocampal SI was altered in 25% of HS and in 70% of 'gliosis only' patients (all p < 0.001). Ipsilateral hippocampus of HS patients had lower volume (mean ± SD 2.86 ± 0.87 ml) compared with that of 'gliosis only' patients (3.4 ± 1.02 ml) and had higher SI than the contralateral hippocampus of HS patients and then the hippocampus of 'gliosis only' patients (all p < 0.01). Conclusion: 'Gliosis only' has different MRI hippocampal characteristics than HS: less volume loss, less increase of the T2-w signal intensity, preservation of internal architecture, and more contralateral affection. [ABSTRACT FROM AUTHOR]

Contrast enhancement of glioblastomas (GBM) is caused by the decrease in relaxation time, T1. Here, we demonstrate that the quantitative measurement of T1 (qT1) discovers a subtle enhancement in GBM patients that is invisible in standard MRI. We assessed the volume change of this 'cloudy' enhancement during radio-chemotherapy and its impact on patients' progression-free survival (PFS). We enrolled 18 GBM patients in this observational, prospective cohort study and measured 3T-MRI pre- and post contrast agent with standard T1-weighted (T1w) and with sequences to quantify T1 before radiation, and at 6-week intervals during radio-chemotherapy. We measured contrast enhancement by subtracting pre from post contrast contrast images, yielding relative signal increase ∆T1w and relative T1 shortening ∆qT1. On ∆qT1, we identified a solid and a cloudy-enhancing compartment and evaluated the impact of their therapy-related volume change upon PFS. In ∆qT1 maps cloudy-enhancing compartments were found in all but two patients at baseline and in all patients during therapy. The qT1 decrease in the cloudy-enhancing compartment post contrast was 21.64% versus 1.96% in the contralateral control tissue ( P < 0.001). It was located at the margin of solid enhancement which was also seen on T1w. In contrast, the cloudy-enhancing compartment was visually undetectable on ∆T1w. A volume decrease of more than 21.4% of the cloudy-enhancing compartment at first follow-up predicted longer PFS ( P = 0.038). Cloudy-enhancing compartment outside the solid contrast-enhancing area of GBM is a new observation which is only visually detectable with qT1-mapping and may represent tumor infiltration. Its early volume decrease predicts a longer PFS in GBM patients during standard radio-chemotherapy. [ABSTRACT FROM AUTHOR]