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Bogdan Draganski

Publications and source records attributed to Bogdan Draganski.

9 recordsLinked to original sources
PubMed2021

1q21.1 distal copy number variants are associated with cerebral and cognitive alterations in humans.

Low-frequency 1q21.1 distal deletion and duplication copy number variant (CNV) carriers are predisposed to multiple neurodevelopmental disorders, including schizophrenia, autism and intellectual disability. Human carriers display a high prevalence of micro- and macrocephaly in deletion and duplication carriers, respectively. The underlying brain structural diversity remains largely unknown. We systematically called CNVs in 38 cohorts from the large-scale ENIGMA-CNV collaboration and the UK Biobank and identified 28 1q21.1 distal deletion and 22 duplication carriers and 37,088 non-carriers (48% male) derived from 15 distinct magnetic resonance imaging scanner sites. With standardized methods, we compared subcortical and cortical brain measures (all) and cognitive performance (UK Biobank only) between carrier groups also testing for mediation of brain structure on cognition. We identified positive dosage effects of copy number on intracranial volume (ICV) and total cortical surface area, with the largest effects in frontal and cingulate cortices, and negative dosage effects on caudate and hippocampal volumes. The carriers displayed distinct cognitive deficit profiles in cognitive tasks from the UK Biobank with intermediate decreases in duplication carriers and somewhat larger in deletion carriers-the latter potentially mediated by ICV or cortical surface area. These results shed light on pathobiological mechanisms of neurodevelopmental disorders, by demonstrating gene dose effect on specific brain structures and effect on cognitive function.

Brain↗
PubMed2006

Temporal and spatial dynamics of brain structure changes during extensive learning.

The current view regarding human long-term memory as an active process of encoding and retrieval includes a highly specific learning-induced functional plasticity in a network of multiple memory systems. Voxel-based morphometry was used to detect possible structural brain changes associated with learning. Magnetic resonance images were obtained at three different time points while medical students learned for their medical examination. During the learning period, the gray matter increased significantly in the posterior and lateral parietal cortex bilaterally. These structural changes did not change significantly toward the third scan during the semester break 3 months after the exam. The posterior hippocampus showed a different pattern over time: the initial increase in gray matter during the learning period was even more pronounced toward the third time point. These results indicate that the acquisition of a great amount of highly abstract information may be related to a particular pattern of structural gray matter changes in particular brain areas.

Adult↗
PubMed2005

Transcranial ultrasound brain perfusion assessment with a contrast agent-specific imaging mode: results of a two-center trial.

BACKGROUND AND PURPOSE: The purpose of this study was to assess brain perfusion with an ultrasound contrast-specific imaging mode and to prove if the results are comparable between 2 centers using a standardized study protocol. METHODS: A total of 32 individuals without known cerebrovascular disease were included in the study. Perfusion studies were performed ipsilaterally in an axial diencephalic plane after intravenous administration of 0.75 mL of Optison. Offline time intensity curves (TIC) were generated in different anatomic regions. Both centers used identical study protocols, ultrasound machines, and contrast agent. RESULTS: In both centers, the comparison of the parameter time to peak intensity (TPI) revealed significantly shorter TPIs in the main vessel structures compared with any parenchymal region of interest (ROI), whereas no significant differences were seen between the parenchymal ROIs. The parameter peak intensity (PI) varied widely interindividually in both centers, whereas the inter-ROI comparison revealed statistical significance (P < 0.05) in most of the cases according to the following pattern: (1) lentiforme nucleus > thalamus and white matter region, (2) thalamus > white matter region, and (3) main vessel > any parenchymal structure. Similar results were achieved in both centers independently. CONCLUSIONS: The study demonstrates that brain perfusion assessment with an ultrasound contrast-specific imaging mode is comparable between different centers using the same study protocol.

Adult↗
PubMed2005

Detection of cardiac right-to-left shunts by contrast-enhanced harmonic carotid duplex sonography.

OBJECTIVE: Paradoxical embolization by cardiac right-to-left shunts (RLS) is increasingly recognized as an important factor for embolic stroke. Contrast-enhanced transcranial Doppler sonography (ce-TCDS) is an established diagnostic tool for RLS detection but is frequently limited because of an inadequate temporal acoustic bone window. The purpose of this study was to determine whether extracranial sonography (ECS) using harmonic frequencies improves detection of RLS. METHODS: Extracranial color duplex sonography using harmonic frequencies enables visualization of even single ultrasound contrast agent microbubbles because of oscillation. Patients with stroke and positive RLS findings on transesophageal echocardiography underwent a simultaneous extracranial and transcranial sonographic examination of the proximal common carotid artery (CCA) and middle cerebral artery (MCA) on the same side. A Valsalva strain was performed for 10 seconds after intravenous bolus injection of a galactose-based nontranspulmonary contrast agent. The B-mode frame sequences of the transverse plane of the CCA obtained by harmonic ECS and the ce-TCDS recordings of high-intensity transient signals from the MCA were analyzed offline. RESULTS: In all patients with RLS, the shunts could be identified by harmonic ECS. A close correlation could be seen between the count of visualized microbubbles in the CCA and the number of high-intensity transient signals detected on ce-TCDS in the ipsilateral MCA. CONCLUSIONS: The results of this study indicate that contrast-enhanced ultrasound harmonic imaging of the CCA using a Valsalva strain might be an optional screening tool for detection of cardiac RLS in patients with insufficient acoustic bone windows.

Carotid Artery, Internal↗
PubMed2004

Bilateral thalamic gray matter changes in patients with restless legs syndrome.

Restless legs syndrome (RLS) is a common neurological disorder of a primary unpleasant sensation with an urge to move the legs occurring at rest. The etiology of idiopathic RLS is unknown and structural cerebral abnormalities have so far not been detected. We studied 51 right-handed patients with an idiopathic restless legs syndrome in two independent samples (Regensburg RLS-group: n = 28, Munich RLS-group: n = 23) and compared them to 51 sex- and age-matched healthy volunteers. High-resolution T1-weighted magnetic resonance imaging (MRI) of each subject was obtained and analyzed using voxel-based morphometry (VBM) to detect regionally specific differences in gray matter between patients and controls. Conjunction analysis was used to combine results from both centers. In patients with idiopathic RLS, both study centers observed independently a bilateral gray matter increase in the pulvinar. In the conjunction analysis including all patients and controls from both study centers, a significant gray matter increase in the pulvinar bilaterally (right: x = 16, y = -21, z = 12, Z = 4.57; left: x = -16, y = -24, z = 12, Z = 4.10) was present. This is the first demonstration of structural changes in the brain of patients with idiopathic RLS. These changes in thalamic structures are either involved in the pathogenesis of RLS or may reflect a consequence of chronic increase in afferent input of behaviorally relevant information.

Adult↗
PubMed2003

Brain perfusion imaging of a craniopharyngioma by transcranial duplex sonography.

BACKGROUND AND PURPOSE: The aim of this study was to test a new ultrasound software tool to assess pathological perfusion in a brain tumor patient. METHODS: Tissue harmonic imaging (THI) enables an improved depiction of brain morphology, employing nonlinear parenchyma and ultrasound contrast agent (UCA) backscatter information. With specialized software, morphological information can be separated from perfusion information. Both can be superimposed at a preferred mixing ratio in a single image. RESULTS: Using THI and a perfluoropropane-based UCA, a pathologic perfusion pattern described by abnormal perfused areas in the tumor region could be demonstrated. After superimposing morphologic and perfusion information, subtle structural tumor inhomogeneities were depicted. Craniopharyngioma structure and perfusion defect were confirmed by T2-weighted and perfusion-weighted magnetic resonance imaging. CONCLUSION: Transcranial duplex sonography in combination with contrast specific imaging methods might be helpful to visualize perfusion defects without loss of morphological information.

Adult↗
PubMed2002

Observation on the integrity of the blood-brain barrier after microbubble destruction by diagnostic transcranial color-coded sonography.

OBJECTIVE: To investigate alteration of the blood-brain barrier from ultrasonic contrast agent destruction by diagnostic transcranial color-coded sonography using gadolinium-enhanced magnetic resonance imaging. METHODS: Healthy male volunteers received 10 mL (400 mg/dL) of Levovist (SH U 508A; Schering AG, Berlin, Germany; n = 6) or 3 mL of Optison (FS069; Mallinckrodt Inc, St Louis, MO; n = 4) followed by 0.3 mmol/kg magnetic resonance imaging contrast agent (Magnevist; Schering) intravenously. Then transcranial color-coded sonography was performed with a conventional color duplex sonographic system, which insonated the brain in a slightly angulated axial plane with temporal average intensity of less than 700 mW/cm2 or acoustic pressure amplitude of less than 2.69 MPa, attenuated by the temporal bone. Before, immediately after, and 2 hours after insonation, T1-weighted axial magnetic resonance imaging was performed. All magnetic resonance images were individually assessed, and T1 signal intensities were measured in 2 regions of interest in both hemispheres at the 3 time points. RESULTS: No focal contrast enhancement or damage to the brain and no significant difference between T1 signal intensities in the right and left brain regions could be detected during early or late phases when either ultrasonic contrast agent was used. CONCLUSIONS: This bioeffects study gives further evidence of the safety of ultrasonic destruction of Levovist and Optison microbubbles by diagnostic transcranial color-coded sonography. However, more subtle local effects may have been missed by gadolinium-enhanced magnetic resonance imaging. Studies on diagnostic contrast-enhanced transcranial color-coded sonography as well as microbubble-based drug delivery strategies should consider ultrasonic contrast agent microbubble characteristics and concentration as well as ultrasound transmission power levels.

Adult↗
PubMedDate not supplied

Preoperative evaluation of carotid artery stenosis: comparison of contrast-enhanced MR angiography and duplex sonography with digital subtraction angiography.

BACKGROUND AND PURPOSE: Contrast-enhanced MR angiography and extracranial color-coded duplex sonography are noninvasive, preoperative imaging modalities for evaluation of carotid artery stenosis. Innovative techniques and improvements in image quality require frequent reassessment of accuracy, reliability, and diagnostic value compared with those of digital subtraction angiography (DSA). We evaluated contrast-enhanced MR angiography and duplex sonography compared with DSA for detection of high-grade carotid artery stenoses. METHODS: Four readers, blinded to clinical symptoms and the outcome of other studies, independently evaluated stenoses on contrast-enhanced MR angiograms in 71 vessels of 39 symptomatic patients. Duplex sonography was also performed in all vessels. The severity of stenosis was defined according to North American Symptomatic Carotid Endarterectomy Trial criteria (0-29%, 30-69%, 70-99%, 100%). Results of both modalities were compared with the corresponding DSA findings. RESULTS: Contrast-enhanced MR angiography had a sensitivity and specificity of 94.9% and 79.1%, respectively, for the identification of carotid artery stenoses of 70% or greater. Sensitivity and specificity of duplex sonography were 92.9% and 81.9%, respectively. Combining data from both tests revealed a sensitivity and specificity of 100% and 81.4%, respectively, for concordant results (80% of vessels). CONCLUSION: Concordant results of contrast-enhanced MR angiography and duplex sonography increase the diagnostic sensitivity to 100%. The reliability of MR angiography is comparable to that of DSA. The combination of contrast-enhanced MR angiography and duplex sonography might be preferable over DSA for preoperative evaluation in most patients, thus reducing the risk of perioperative morbidity and improving the overall outcome.

Adult↗