RESUMEN
BACKGROUND: Diffuse damage to the periventricular white matter has recently been suggested to be a cause of the cognitive deficits seen following preterm birth. It is unclear whether this form of injury can be visualised on MR imaging, but one group has described diffuse excessive high signal intensity (DEHSI) as a possible form of diffuse white matter injury. This finding is dependent on window imaging and the subjective assessment of the reviewer, but little data have been published on the degree of subjectivity on its appearance among raters. OBJECTIVE: To assess the subjectivity of DEHSI on conventional and ultrafast T2-weighted MR imaging following preterm birth. MATERIALS AND METHODS: An observational study of 40 preterm infants who had MR imaging of the brain around term-equivalent age, including conventional fast spin-echo (FSE) and ultrafast single-shot fast spin-echo (SSFSE) T2-weighted sequences in the axial plane. Images were anonymised and scored twice by four observers for the presence of DEHSI. Inter- and intra-observer agreement were calculated. RESULTS: Sixty-five percent of conventional and 100% of the ultrafast images were of diagnostic quality. DEHSI was noted in between 0% and 69.2% of conventional images and 27.5-90% of the ultrafast images. Inter- and intra-observer agreement ranged from none to moderate. CONCLUSION: The visual appearances of DEHSI on conventional FSE and ultrafast SSFSE T2-W images are highly subjective, limiting its clinical application.
Asunto(s)
Lesiones Encefálicas/diagnóstico por imagen , Imagen por Resonancia Magnética , Femenino , Humanos , Recién Nacido , Recien Nacido Prematuro , Masculino , Variaciones Dependientes del Observador , Embarazo , RadiografíaRESUMEN
Developmental dyslexia is associated with problems in a range of linguistic and non-linguistic skills. Some of those problems have been attributed to dysfunction of the cerebellum and its associated neural systems. Two studies of cerebellar structure were undertaken by our group. In Study 1, white and grey matter volumes in the cerebellum were investigated in 10 dyslexic and 11 control adult male, right-handed participants using whole-brain volumetric MRI (3D-T1-weighted data sets with a spatial resolution of 0.8 x 0.8 x 0.8 mm(3)). The key finding was that the dyslexic group had a larger volume of white matter in both cerebellar hemispheres, differences that remained significant even when adjusting for total cerebellar volume. In Study 2, with the same participants, long-echo-time proton spectroscopy was used to investigate the ratios of the metabolites choline (Cho), N-acetylaspartate (NAA), and creatine (Cr) in the cerebellar hemispheres and vermis. Two significant differences were found: The dyslexic group had a lower ratio of NAA/Cho in the right cerebellar hemisphere together with a higher ratio of Cho/Cr in the left cerebellar hemisphere. Although it is difficult to interpret the volumetric and spectroscopic results unambiguously, taken together they suggest two possible interpretations: excessive connectivity or abnormal myelination.
Asunto(s)
Cerebelo/metabolismo , Cerebelo/patología , Dislexia/metabolismo , Dislexia/patología , Adulto , Estudios de Casos y Controles , HumanosRESUMEN
PURPOSE: To estimate the levels of basal ganglia iron levels in Parkinson's disease (PD) using the PRIME MR sequence at 3.0 Tesla, in relation to patients' motor symptom severity. MATERIALS AND METHODS: Seventy patients with PD and 10 healthy controls underwent assessment of movement and MR imaging. Mean R2' relaxation rates were recorded in the substantia nigra, frontal white matter and in the rostral, mid, and caudal putamen. RESULTS: R2' relaxation rates were significantly higher in patients with PD than in healthy controls. R2' in the most affected substantia nigra correlated with PD patients' motor symptom severity, but not with disease duration. Neuroradiological observation revealed a rostral to caudal "gradient" of putaminal hypointensity. This was substantiated by the finding that the mid and caudal putamen showed significantly higher R2' relaxation rates, consistent with higher iron levels in PD relative to the healthy controls. CONCLUSION: MRI at 3.0 Tesla suggests that substantia nigra iron levels are increased and linked to the severity of motor symptoms experienced in PD. Findings consistent with increased iron levels in the PD putamen are shown, in a region-specific rostral to caudal gradient.