Gábor Rudas

Using diffusion MRI for measuring the temperature of cerebrospinal fluid within the lateral ventricles

Aim:  Hypothermia is often induced to reduce brain injury in newborns, following perinatal hypoxic–ischaemic events, and in adults following traumatic brain injury, stroke or cardiac arrest. We aimed to devise a method, based on diffusion‐weighted MRI, to measure non‐invasively the temperature of the cerebrospinal fluid in the lateral ventricles.

COL4A2 mutation causing adult onset recurrent intracerebral hemorrhage and leukoencephalopathy

Abstract Type IV collagen α1 and α2 chains form heterotrimers that constitute an essential component of basement membranes. Mutations in COL4A1, encoding the α1 chain, cause a multisystem disease with prominent cerebrovascular manifestations, including porencephaly, bleeding-prone cerebral small vessel disease, and intracranial aneurysms. Mutations in COL4A2 have only been reported in a few porencephaly families so far. Herein, we report on a young adult patient with recurrent intracerebral hemorrhage, leukoencephalopathy, intracranial aneurysms, nephropathy, and myopathy associated with a novel COL4A2 mutation. We extensively investigated a 29-year-old male patient with recurrent deep intracerebral hemorrhages causing mild motor and sensory hemisyndromes. Brain MRI showed deep intracerebral hemorrhages of different age, diffuse leukoencephalopathy, multiple cerebral microbleeds and small aneurysms of the carotid siphon bilaterally. Laboratory work-up revealed significant microscopic hematuria and elevation of creatine-kinase. Genetic testing found a de novo glycine mutation within the COL4A2 triple helical domain. The presented case completes the spectrum of cerebral and systemic manifestations of COL4A2 mutations that appears to be very similar to that in COL4A1 mutations. Therefore, we emphasize the importance of screening both COL4A1 and COL4A2 in patients showing recurrent intracerebral hemorrhage of unknown etiology, particularly if associated with leukoencephalopathy.

DNA integrity of human leukocytes after magnetic resonance imaging

Abstract Purpose: This study focuses on the effects of high-field (3T) magnetic resonance imaging (MRI) scans on the DNA integrity of human leukocytes in vitro in order to validate the study where genotoxic effects were obtained and published by Lee et al. Materials and methods: The scanning protocol and exposure situation were the same as those used under routine clinical brain MRI scan. Peripheral blood samples from healthy non-smoking male donors were exposed to electromagnetic fields (EMF) produced by 3T magnetic resonance imaging equipment for 0, 22, 45, 67, and 89 min during the scanning procedure. Samples of positive control were exposed to ionizing radiation (4 Gy of 60Co-γ). Single breaks of DNA in leukocytes were detected by single-cell gel electrophoresis (Comet assay). Chromosome breakage, chromosome loss and micronuclei formations were detected by a micronucleus test (MN). Three independent experiments were performed. Results: The data of comet tail DNA%, olive tail moment and micronucleus frequency showed no DNA damages due to MRI exposure. Conclusions: The results of the Comet assay and the micronucleus test indicate that the applied exposure of MRI does not appear to produce breaks in the DNA and has no significant effect on DNA integrity.

The Differentiation of Amnestic Type MCI from the Non-Amnestic Types by Structural MRI

Introduction: While amnestic mild cognitive impairment (aMCI) and non-amnestic mild cognitive impairment (naMCI) are theoretically different entities, only a few investigations studied the structural brain differences between these subtypes of mild cognitive impairment. The aim of the study was to find the structural differences between aMCI and naMCI, and to replicate previous findings on the differentiation between aMCI and healthy controls. Methods: Altogether 62 aMCI, naMCI, and healthy control subjects were included into the study based on the Petersen criteria. All patients underwent a routine brain MR examination, and a detailed neuropsychological examination. Results: The sizes of the hippocampus, the entorhinal cortex and the amygdala were decreased in aMCI relative to naMCI and to controls. Furthermore the cortical thickness of the entorhinal cortex, the fusiform gyrus, the precuneus and the isthmus of the cingulate gyrus were significantly decreased in aMCI relative to naMCI and healthy controls. The largest differences relative to controls were detected for the volume of the hippocampus (18% decrease vs. controls) and the cortical thickness (20% decrease vs. controls) of the entorhinal cortex: 1.6 and 1.4 in terms of Cohens d. Only the volume of the precuneus were decreased in the naMCI group (5% decrease) compared to the control subjects: 0.9 in terms of Cohens d. Significant between group differences were also found in the neuropsychological test results: a decreased anterograde, retrograde memory, and category fluency performance was detected in the aMCI group relative to controls and naMCI subjects. Subjects with naMCI showed decreased letter fluency relative to controls, while both MCI groups showed decreased executive functioning relative to controls as measured by the Trail Making test part B. Memory performance in the aMCI group and in the entire sample correlated with the thickness of the entorhinal cortex and with the volume of the amygdala. Conclusion: The amnestic mild cognitive impairment/non-amnestic mild cognitive impairment separation is not only theoretical but backed by structural imaging methods and neuropsychological tests. A better knowledge of the MCI subtypes can help to predict the direction of progression and create targeted prevention.

Investigating the need of triggering the acquisition for infant diffusion MRI: A quantitative study including bootstrap statistics

Diffusion weighted magnetic resonance imaging is increasingly being used for neonatal and young pediatric subjects. Our purpose was to investigate a) whether cardiac triggering was needed to reduce variability of diffusion (tensor) imaging data, b) how pulsation artifacts affect the fitted diffusion tensor when triggering is not used and c) the feasibility of triggered data acquisition in neonates and young children. Data were collected from 11 infants and 7 adults. In seven infants and seven adults, diffusion encoding was applied solely along the z gradient direction with and without cardiac triggering. Non-parametric bootstrap statistical methods were applied to investigate the dependence of variance on triggering. One infant and all adults served as test–retest controls. From the remaining three infants diffusion tensor imaging data were acquired with and without triggering. Our findings that used the repeated measurements in a single diffusion-encoding direction indicated that without triggering the variability in the data was increased significantly both in infants and adults. When collecting diffusion tensor data in infants, this increased variability results in erroneous fractional anisotropy values and artifactual fiber direction estimates. Contrary to previous reports but supported by our findings involving adults, pulsation artifacts were present in a larger extent of the brain in the infant population. In conclusion, triggering is feasible in young subjects and is preferred when acquiring diffusion MRI data. In doing so, the amount of erroneous estimations due to image artifacts will be minimized, which in turn will lead to more specific and less ambiguous interpretations. Although fitting the pulse-monitoring device requires additional set-up time, the total imaging time is usually shorter than acquiring multiple data sets to compile a single, artifact-free set.

Aortic thrombosis diagnosed by ultrasound

A neonate developed aortic thrombosis following catheterization of the umbilical artery. The thrombus was identified and followed up by ultrasonography. Fibrinolytic therapy led to the almost complete disappearance of the aortic thrombus but the child died of cerebral haemorrhage. Physicians should be alerted to the possibility of aortic thrombosis in neonates following umbilical arterial catheterization. Ultrasonography is an appropriate method for diagnosis and follow-up in these cases.

Changes in echogenicity of spinal subarachnoid space associated with intracranial hemorrhage: new observations

Purpose. The role of subarachnoid blood and secondary, sterile inflammation in the pathogenesis of posthemorrhagic hydrocephalus (PHH) is not well understood. The aims of this study were to study the frequency and rate of spread of blood into the spinal subarachnoid space (SSS) and to evaluate the relationship of this finding and PHH.¶Materials and methods. Nine premature babies with major intracerebral hemorrhage (ICH, grade 3 or higher), and ten premature infants with minor ICH (grade 1) or no evidence of ICH (control group) were identified and underwent serial cranial and spinal sonography at the time of initial diagnosis, 12–24 h after the ICH and weekly thereafter for at least 9 weeks. Sagittal and axial scans of the thoracolumbar spine were obtained and evaluated for the presence of echogenic debris in the dorsal SSS. Six additional patients who had cranial and spinal sonography died within the 1st week of life and underwent post-mortem examinations.¶Results. The SSS was echo-free (normal) in all cases at the time of initial sonographic diagnosis of ICH. Within 24 h, all babies with major ICH had developed increased echogenicity of the cervical and thoracic SSS. Echogenicity of the SSS decreased gradually over several weeks. Although transient ventricular dilatation was present in every patient, only one patient had rapidly progressive PHH requiring shunt placement. Transient cysts of the cervicothoracic subarachnoid space were identified in two patients 6–7 weeks after ICH. The subarachnoid space remained echo-free in all control infants At autopsy, all four infants with echogenic spinal debris had blood or blood products in the spinal subarachnoid space, whereas two infants with echo-free spinal images did not.¶Conclusions. Spread of blood from the ventricular system into the spinal subarachnoid space after ICH is common and can be seen within 24 h of initial ICH. Subarachnoid blood is associated with post-hemorrhagic ventricular dilatation and transient spinal subarachnoid cyst formation.

What can DTI tell about early cognitive impairment? – Differentiation between MCI subtypes and healthy controls by diffusion tensor imaging

Mild cognitive impairment (MCI) gained a lot of interest recently, especially that the conversion rate to Alzheimer Disease (AD) in the amnestic subtype (aMCI) is higher than in the non-amnestic subtype (naMCI). We aimed to determine whether and how diffusion-weighted MRI (DWI) using the diffusion tensor model (DTI) can differentiate MCI subtypes from healthy subjects. High resolution 3D T1W and DWI images of patients (aMCI, n = 18; naMCI, n = 20; according to Petersen criteria) and controls (n = 27) were acquired at 3T and processed using ExploreDTI and SPM. Voxel-wise and region of interest (ROI) analyses of fractional anisotropy (FA) and mean diffusivity (MD) were performed with ANCOVA; MD was higher in aMCI compared to controls or naMCI in several grey and white matter (GM, WM) regions (especially in the temporal pole and the inferior temporal lobes), while FA was lower in WM ROI-s (e.g. left Cingulum). Moreover, significant correlations were identified between verbal fluency, visual and verbal memory performance and DTI metrics. Logistic regression showed that measuring FA of the crus of fornix along GM volumetry improves the discrimination of aMCI from naMCI. Additional information from DWI/DTI aids preclinical detection of AD and may help detecting early non-Alzheimer type dementia, too.

Cortical Hand Knob Stroke: Report of 25 Cases

BACKGROUND Although uncommon, cortical hand knob territory stroke is a well-defined stroke entity that mimics peripheral nerve damage. Atherosclerosis and hypertension are the most prevalent risk factors for the disease. Embolic origin, either artery-to-artery or cardioembolic, has been suggested as the most probable underlying mechanism. MATERIALS AND METHODS Twenty-five patients with isolated hand palsy due to central origin were admitted to our department between 2006 and 2016. Cortical lesions were proven by either computed tomography or magnetic resonance imaging. RESULTS The average age was 67 ± 12 years. Most of the cases were first-ever strokes (n = 23, 92%). Isolated infarct in the hand knob region was found in 18 of the 25 cases, whereas 7 had multiple acute infarctions. Supra-aortic atherosclerosis was found in 21 patients, 8 of them had 50% or greater ipsilateral stenosis of the internal carotid artery. Hypertension was the second most prevalent risk factor (n = 20, 80%). Quick improvement of symptoms was seen in almost every case (mean follow-up 17.5 months), 9 patients showed complete recovery, whereas 2 remained disabled and 1 died due to a malignant disease. Three patients suffered a recurrent stroke on follow-up. CONCLUSIONS We conclude that distal arm paresis is a rare presentation of acute stroke with usually benign course.

Diffusion weighted magnetic resonance imaging demonstrates tumor response following palliative embolization of a recurrent shoulder plasmacytoma

We report the palliative embolization and functional imaging follow-up of a recurrent shoulder plasmacytoma. The multiple myeloma patient complained of severe pain and discomfort, while he could not tolerate further chemotherapy. The left shoulder lesion had earlier received a high dose of irradiation. Thus, the well-vascularized lesion was embolized via feeding arteries branching off from the left subclavian artery in two sessions. The patient’s symptoms rapidly improved post-embolization and the serum free light chain ratio stabilized at a lower level. The follow-up magnetic resonance image showed increased diffusivity in previously restricted tumor foci. This has negatively correlated with the decreased fludeoxyglucose uptake on PET, suggesting post-embolization necrosis.