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T A Yousry

Publications and source records attributed to T A Yousry.

At least 19 recordsLinked to original sources
PubMed2006

Neuroimaging findings in human prion disease.

Imaging occupies an important role in the investigation of dementia and neurodegenerative disease. The role of imaging in prion disease used to be one of exclusion of other conditions. Over the past decade, the non-invasive nature of MRI, the improved range of magnetic resonance sequences and the availability of clinical and neuropathological correlation have led to a more prominent position of MRI and its inclusion in the diagnostic criteria for variant Creutzfeldt-Jakob disease. As experience of imaging in human prion disease increases, patterns of change related to strain and genotype may improve the diagnostic potential of imaging in the future, may reduce the need for more invasive testing and prove useful in future therapeutic trials. This paper reviews the current knowledge of imaging appearances in human prion disease.

Creutzfeldt-Jakob Syndrome↗
PubMed2004

A review of structural magnetic resonance neuroimaging.

Magnetic resonance imaging (MRI) is often divided into structural MRI and functional MRI (fMRI). The former is a widely used imaging technique in research as well as in clinical practice. This review describes the more important developments in structural MRI in recent years, including high resolution imaging, T2 relaxation measurement, T2*-weighted imaging, T1 relaxation measurement, magnetisation transfer imaging, and diffusion imaging. The principles underlying these techniques, as well as their use in research and in clinical practice, will be discussed.

Brain↗
PubMed2003

Prospective evaluation of neurological complications after allogeneic bone marrow transplantation.

OBJECTIVE: To determine the spectrum and frequency of neurologic sequelae after allogeneic bone marrow transplantation (BMT) and to define a risk profile of the patients. METHODS: A prospective follow-up of 71 allogeneic bone marrow recipients 14 +/- 3 months after transplantation. Patients underwent a neurologic examination, a neuropsychological test battery, and cranial MRI before and after BMT. RESULTS: A large proportion of patients (65%) developed sequelae after BMT. Acute complications of defined etiology occurred in 18% of the patients and led to death in 9% of the study population. A total of 47% of the patients developed new neurologic abnormalities of undefined origin that were mild and subacute and predominantly affected the peripheral nervous system. The cognitive and neuroradiologic outcome was favorable in a majority of these patients, but a small subgroup exhibited cognitive deterioration and white matter lesions. Risk factor analysis identified acute graft-versus-host disease (GvHD) and other variables partly related to GvHD such as long-lasting immunosuppression as the main predictors of sequelae after allogeneic BMT. The authors have established an association with various factors but, owing to the observational character of this study, conclusions about the etiology of the findings are unclear. CONCLUSION: Neurologic complications significantly contribute to the morbidity and mortality of patients receiving allogeneic BMT. Subclinical abnormalities, cognitive deficits, and white matter lesions detected 1 year after BMT in a subgroup of patients may be related to more extensive CNS changes observed after transplantation in an earlier retrospective study and may be associated with the risk factor chronic GvHD/immunosuppression.

Adolescent↗
PubMed2003

The effect of interferon beta-1b on quantities derived from MT MRI in secondary progressive MS.

BACKGROUND: Magnetization transfer (MT) MRI can provide in vivo markers reflecting the severity of irreversible, MS-related brain damage occurring within and outside T2-visible lesions. OBJECTIVE: To assess the effect of interferon (IFN) beta-1b treatment on the accumulation of brain damage in patients with secondary progressive (SP) MS, measured using MT MRI. METHODS: Eighty-two patients with SPMS from five centers participating in a European, multicenter, double-blind, placebo-controlled trial of IFNbeta-1b in SPMS underwent brain T2-weighted and MT MRI at baseline. Evaluable follow-up data were available for 75 patients at 12 months, 54 at 24 months, and 47 at 36 months. MT MRI scans were postprocessed and analyzed to obtain histograms of MT ratio (MTR) values from the whole brain. A region of interest-based analysis of MTR values from the normal-appearing white matter (NAWM) was also performed. RESULTS: In both the treatment arms, there was a decrease of average brain MTR values from baseline to month 24 (mean change -4.9%) and month 36 (mean change -4.3%). These changes were significant for the placebo group at both timepoints and for the IFNbeta-1b group at month 24 only, with no significant treatment effect. A decrease of NAWM MTR was also observed, with no significant difference between the two treatment arms. CONCLUSION: In this cohort of patients with secondary progressive MS, interferon beta-1b did not show an overall effect on the worsening of magnetization transfer MRI measures, when compared with placebo. The data show that change in magnetization transfer ratio is a promising tool for monitoring disease evolution in secondary progressive MS and that the information obtained from magnetization transfer MRI complements that obtained from MRI measures of lesion load and inflammation.

Adult↗
PubMed2003

Inferior central sulcus: variations of anatomy and function on the example of the motor tongue area.

We wanted to define the position of the primary motor tongue area (MTA) by using functional magnetic resonance imaging (fMRI) to display the MTA in relation to the inferolateral segment of the central sulcus (CS). The anatomy of the inferolateral segment was analyzed in 24 healthy subjects, using the magnetization prepared rapid acquisition gradient echo sequence. The position of the MTA was defined in 11 subjects by using fMRI to identify the sites of maximal activation for each subject in relation to that subject's own CS. The MTA was then displayed in three orthogonal planes, and in lateral surface reformations. The inferolateral segment displayed two distinct curves in 33 of 48 (69%) hemispheres, three curves in 6%, and four curves in 23%. Significant paradigm correlated activations were found in every hemisphere. Thereof 89 local maxima were determined, with 84 (94%) located in the region of the CS. Sixty-seven (80%) of the 84 CS activations lay along the two lowest curves of the CS. In 86% of cases, activations situated in the middle and deep portion of the anterior bank of the CS were encompassed within the three axial sections centered on the cella media of the lateral ventricles. In conclusion, the variability of the inferior CS segment precluded the assignment of the MTA to a specific anatomic configuration. However, the position of the MTA could be approximated by the intersection between the CS and the three axial planes through, just above, and just below the cella media of the lateral ventricles.

Adult↗
PubMed2003

High resolution MRI of the brain at 4.7 Tesla using fast spin echo imaging.

Over recent years, high field MR scanners (3 T and above) have become increasingly widespread due to potential advantages such as higher signal-to-noise ratio. However, few examples of high resolution images covering the whole brain in reasonable acquisition times have been published to date and none have used fast spin echo (FSE), a sequence commonly employed for the acquisition of T(2) weighted images at 1.5 T. This is mostly due to the increased technical challenges associated with uniform signal generation and the increasingly restrictive constraints of current safety guidelines at high field. We investigated 10 volunteers using an FSE sequence optimized to the 4.7 T environment. This sequence allows the acquisition of 17- and 34-slice data sets with an in-plane resolution of approximately 500 microm x 500 microm and a slice thickness of 2 mm, in 5 min 40 s and 11 min 20 s, respectively. The images appear T(2) weighted, although the contrast is due to the combined effects of chosen echo time, magnetization transfer, direct radio frequency saturation and diffusion as well as the T(1) and T(2) relaxation times of the tissue. The result is an excellent detailed visualization of anatomical structures, demonstrating the great potential of 4.7 T MRI for clinical applications. This paper shows that, with careful optimization of sequence parameters, FSE imaging can be used at high field to generate images with high spatial resolution and uniform contrast across the whole brain within the prescribed power deposition limits.

Adult↗
PubMed2002

Contribution of cervical cord MRI and brain magnetization transfer imaging to the assessment of individual patients with multiple sclerosis: a preliminary study.

This study was performed to assess how established diagnostic criteria for brain magnetic resonance imaging (MRI) interpretation in cases of suspected multiple sclerosis (MS) (Barkhofs criteria) would perform in the distinction of MS from other diseases and whether other MR techniques (cervical cord imaging and brain magnetization transfer imaging [MTI]), might help in the diagnostic work-up of these patients. We retrospectively identified 64 MS and 59 non-MS patients. The latter group included patients with systemic immune-mediated disorders (SID; n=44) and migraine (n=15). All patients had undergone MRI scans of the brain (dual echo and MTI) and of the cervical cord (fast short-tau inversion recovery). The number and location of brain T2-hyperintense lesions and the number and size of cervical cord lesions were assessed. Brain images were also postprocessed to quantify the total lesion volumes (TLV) and to create histograms of magnetization transfer ratio (MTR) values from the whole of the brain tissue. Barkhofs criteria correctly classified 108/123 patients, thus showing an accuracy of 87.8%. "False negative" MS patients were 13, while 2 patients with systemic lupus erythematosus (SLE) were considered as "false positives". Using brain T2 TLV, nine of the "false negative" patients were correctly classified. Correct classification of 10 MS patients and both the SLE patients was possible based upon the presence or absence of one cervical cord lesion. Two MS patients with negative Barkhofs criteria and no cervical cord lesions were correctly classified based on their brain MTR values. Overall, only one MS patient could not be correctly classified by any of the assessed MR quantities. These preliminary data support a more extensive use of cervical cord MRI and brain MTI to differentiate between MS and other disorders in case of incondusive findings on T2-weighted MRI scans of the brain.

Adolescent↗
PubMed2002

[Initial experiences with adjuvant locoregional radioimmunotherapy using 131I-labeled monoclonal antibodies against tenascin (BC-4) for treatment of glioma (WHO III and IV)].

AIM: None of the established treatments (surgery, radiotherapy, chemotherapy) for malignant glioma has improved its very poor prognosis. Adjuvant locoregional radio-immunotherapy (RIT) represents a new therapeutic approach. We present our initial experience with this therapeutic tool with respect to adverse effects, biokinetics and clinical follow-up. METHODS: Following surgery and radiotherapy, 12 patients with glioma (4, WHO stage III; 8, WHO stage IV) underwent 1-5 RIT-cycles (average dose 1100 MBq 131labelled monoclonal BC-4 antibodies) at six week intervals. Follow-up included serial FDG-PET and MRI investigations. Evaluation of biokinetics included whole body scans, together with analysis of blood, urine and fluid from the tumor cavity. RESULTS: Following RIT, four patients experienced temporary seizures, which, in one case, were associated with temporary aphasia. Eight patients developed HAMA (human anti-mouse antibodies) during follow-up. Mean biologic half-life of the radiopharmaceutical in the resection cavity was 3.9 d (range: 1.0-10.2 d) and remained stable intraindividually during further RIT-cycles. The antibody/radionuclide conjugate remained stable in the tumor cavity for at least 5 d. Median survival presently stands at 18.5 months compared to 9.7 months in a historical patient group (n = 89) undergoing conventional therapeutic strategies. Five patients show no signs of recurrence. In three patients with post-surgical evidence of residual tumor, one patient showed partial remission, one stable disease, and one progressive disease during RIT. Four patients without evidence of residual tumor mass at the beginning of RIT developed recurrence during therapy. CONCLUSIONS: Initial experience demonstrates that locoregional RIT is a well tolerated treatment modality that may represent a promising new approach in the management of patients with malignant glioma. Advantages of local application include passage of the blood-brain barrier, high concentration of activity within the resection cavity and low systemic toxicity.

Adult↗
PubMed2001

The effect of IFNbeta-1b on the evolution of enhancing lesions in secondary progressive MS.

BACKGROUND: After the resolution of contrast enhancement, the majority of new MS lesions become isointense with surrounding white matter on T1-weighted MRI. Less commonly, a hypointense T1 lesion develops, representing the development of more severe focal tissue damage. Interferon beta (IFNbeta) reduces both the number of new enhancing lesions and the duration of contrast enhancement. OBJECTIVE: To determine if IFNbeta affects the degree of tissue damage within new lesions and if its effects are related to lesion size. METHODS: One hundred twenty-five patients with secondary progressive MS from seven European sites were randomized to receive either IFNbeta-1b or placebo. Monthly, contrast-enhanced T1-weighted MR images were acquired at baseline, at months 1 to 6, and at months 19 to 24. The size of all new enhancing lesions developing between months 1 and 6 was recorded and their appearance at follow-up documented. RESULTS: In the first 6 months, fewer new enhancing lesions occurred in the IFNbeta-1b arm. This difference was greater for small (70% decrease) than for large (46% decrease) lesions. Hypointense T1 lesions were more likely to form from large (25%) than from small (9%) enhancing lesions in both treatment arms. Patients taking IFNbeta-1b developed fewer hypointense T1 lesions; however, the proportion of enhancing lesions developing into hypointense T1 lesions was similar in both arms. CONCLUSION: IFNbeta-1b reduced the number of new enhancing lesions, with a greater effect on small lesions. However, when a new enhancing lesion did become established, treatment with IFNbeta-1b did not alter its subsequent course.

Adult↗
PubMed2001

A magnetic resonance imaging study of the cervical cord of patients with CADASIL.

The authors obtained MR and magnetization transfer (MT) imaging of the cervical cord from 25 patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). They found no conventional MR abnormalities, but a reduced peak height of the MT ratio (MTR) histogram. This suggests a reduced amount of "truly" normal cord tissue in CADASIL. A significant correlation was found between the extent of brain lesions and cord MTR, suggesting wallerian degeneration as the substrate of the cord MTR changes.

Adult↗
PubMed2001

Acute severe spinal cord dysfunction in bacterial meningitis in adults: MRI findings suggest extensive myelitis.

BACKGROUND: Bacterial meningitis is rarely complicated by acute spinal cord involvement (eg, myelitis, ischemic infarction, spinal abscess, or epidural hemorrhage). In spinal cord dysfunction, magnetic resonance imaging (MRI) is the imaging modality of choice. Still, MRI findings of myelitis due to bacterial meningitis in adults have not been reported. METHODS: Spinal MRIs were obtained during the acute stage of meningitis and on follow-up in 3 adults with bacterial meningitis that was complicated by paraparesis or tetraparesis and bowel and bladder incontinence. The causative pathogens were Streptococcus pneumoniae and Neisseria meningitidis; in 1 patient, the pathogen was not identified. RESULTS: In all cases, spinal MRI ruled out a compression of the cord by an extramedullary mass but demonstrated hyperintensities on T2-weighted images that predominantly involved the gray matter and extended from the cervical to the lumbar cord. Leptomeningeal and discrete nodular intramedullary enhancement on T1-weighted images was detected only in 1 patient. Follow-up examinations revealed that hyperintensities resolved completely in 1 patient, while a central cavitation developed in the cervical spinal cord of another, and the MRI findings were progressive during the first 4 weeks in the third patient. In all cases, severe paresis and bowel and bladder incontinence persisted. CONCLUSION: We demonstrate for the first time the MRI findings of adults with acute spinal cord involvement during bacterial meningitis. Magnetic resonance imaging showed central intramedullary hyperintensities on T2-weighted images that extended from the cervical to the lumbar cord, indicating myelitis. Clinical follow-up examinations suggest that myelitis during bacterial meningitis has an unfavorable prognosis.

Adolescent↗
PubMed2001

Noninvasive follow-up of GDC-treated saccular aneurysms by MR angiography.

The aim of this study was to determine sensitivity and specificity of magnetic resonance angiography (MRA) for the assessment of durable occlusion of intracranial aneurysms with Guglielmi detachable coils (GDC) and to point out the influence of MRA results in re-intervention strategies. Forty-five patients with 54 aneurysms that were previously treated by endovascular occlusion with GDC were selected for this study. All patients underwent digital subtraction angiography (DSA) and MRA examinations on the same day. The time-of-flight MRA studies were performed on a 1-T scanner. The MRA images were first read by radiologists who were not aware of the DSA results. In a second consensus reading by the neuroradiologists who had performed all interventional procedures of this series, the decision was made as to whether re-treatment was necessary. The distribution of aneurysm sizes, configurations and treatment results were sufficient for an unbiased evaluation. The first blinded evaluation revealed a sensitivity of 71% and a specificity of 95% for MRA assessment of aneurysm reperfusion. In the second consensus reading, the sensitivity increased to 92% and the specificity was 98%. The blinded reading indicates that MRA is a useful adjunct to DSA for the assessment of durable results after endovascular treatment of intracranial aneurysms. In the consensus reading it became obvious that sensitivity and specificity of MRA can be increased to 92 and 98%, respectively, if the results were evaluated by experienced neuroradiologists, including prior knowledge of all other examinations. We have already increased the follow-up intervals for DSA and use MRA intermittently, based on these results.

Adult↗
PubMed2001

Improved interobserver agreement for visual detection of active T2 lesions on serial MR scans in multiple sclerosis using image registration.

The aim of this study was to analyse the effect of image registration on interobserver agreement in the visual detection of active multiple sclerosis (MS) lesions from serial magnetic resonance (MR) scans. T2W spin-echo MR scans (3-mm slices) of 16 MS patients participating in a treatment trial were selected. For each patient, two pairs of scans were used: an original (i. e., non-registered) and a registered pair. For the original pair, baseline and month 6 were used, and for the registered pair month 3 and 9. For registration an automatic matching algorithm based on Mutual Information was used. Six observers identified active lesions on both original and registered scans. Kappa values were calculated to assess interobserver agreement. Reslicing caused a slight blurring of the images, but near perfect registration. The kappa value of 0.35 +/- 0.07 for new lesions on original images improved to 0.62 (+/- 0.06) by registration (p = 0.004). For enlarging lesions on original images it was extremely poor (kappa 0.11 +/- 0.05), and did not benefit much by registration (kappa 0.20 +/- 0.11). Thus, image registration improved interobserver agreement for visual detection of new lesions. For enlarging lesions, registration improved agreement but still not to a satisfactory level.

Adult↗
PubMed2001

Ictal ECD-SPECT differentiates between temporal and extratemporal epilepsy: confirmation by excellent postoperative seizure control.

We investigated whether ictal single photon emission computed tomography (SPECT) with 99Tcm-ethyl cysteinate dimer (ECD) could differentiate between temporal (TE) and extratemporal epilepsy (ETE) in 30 consecutive patients (n = 21 for TE, n = 9 for ETE), all of whom had excellent postoperative seizure control (class I according to Engel's classification). Ictal SPECT showed isolated temporal hyperperfusion in 90% (19 out of 21) of the TE patients and normal perfusion in two patients. All the ETE patients had ictal SPECT findings consistent with extratemporal seizure onset. The sensitivity of ictal ECD-SPECT for correct localization of the seizure onset zone was 80% in all patients, 86% in TE patients and 66% in ETE patients. Although ictal ECD-SPECT has a lower sensitivity in ETE than in TE, it can be used to clearly distinguish between TE and ETE. It provides non-invasive imaging information for use in further diagnostic and treatment strategies in patients with drug-resistant focal epilepsy.

Adolescent↗
PubMed2001

Multisensory cortical signal increases and decreases during vestibular galvanic stimulation (fMRI).

Functional magnetic resonance imaging blood-oxygenation-level-dependent (BOLD) signal increases (activations) and BOLD signal decreases ("deactivations") were compared in six healthy volunteers during galvanic vestibular (mastoid) and galvanic cutaneous (neck) stimulation in order to differentiate vestibular from ocular motor and nociceptive functions. By calculating the contrast for vestibular activation minus cutaneous activation for the group, we found activations in the anterior parts of the insula, the paramedian and dorsolateral thalamus, the putamen, the inferior parietal lobule [Brodmann area (BA) 40], the precentral gyrus (frontal eye field, BA 6), the middle frontal gyrus (prefrontal cortex, BA 46/9), the middle temporal gyrus (BA 37), the superior temporal gyrus (BA 22), and the anterior cingulate gyrus (BA 32) as well as in both cerebellar hemispheres. These activations can be attributed to multisensory vestibular and ocular motor functions. Single-subject analysis in addition showed distinctly nonoverlapping activations in the posterior insula, which corresponds to the parieto-insular vestibular cortex in the monkey. During vestibular stimulation, there was also a significant signal decrease in the visual cortex (BA 18, 19), which spared BA 17. A different "deactivation" was found during cutaneous stimulation; it included upper parieto-occipital areas in the middle temporal and occipital gyri (BA 19/39/18). Under both stimulation conditions, there were signal decreases in the somatosensory cortex (BA 2/3/4). Stimulus-dependent, inhibitory vestibular-visual, and nociceptive-somatosensory interactions may be functionally significant for processing perception and sensorimotor control.

Acoustic Stimulation↗
PubMed2001

Correlations between clinical findings and magnetization transfer imaging metrics of tissue damage in individuals with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy.

BACKGROUND AND PURPOSE: We obtained magnetization transfer imaging (MTI) scans from individuals with cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) (1) to investigate the presence, extent, and nature of pathology in white and gray matter outside proton density (PD)-visible lesions; (2) to quantify the degree of tissue damage occurring in lesions seen on PD-weighted scans; and (3) to correlate MTI-derived measures of disease burden with age, physical disability, and cognitive performance. METHODS: Dual-echo, T1-weighted, and MTI scans of the brain were obtained from 33 individuals with CADASIL and 12 control subjects. Magnetization transfer ratio (MTR) values from PD-visible lesions, normal-appearing white matter (NAWM), and normal-appearing gray matter (NAGM) were measured. Histograms of MTR from the whole brain and normal-appearing brain tissue were also produced. RESULTS: All MTR values from NAWM and NAGM regions studied were significantly lower for individuals with CADASIL than for control subjects, with the exception of those obtained from the NAWM of the infratentorial structures and the NAGM of the occipital cortex. The average MTR from PD lesions in individuals with CADASIL was significantly lower than that from all the NAWM regions. Average MTR and peak location from whole-brain and normal-appearing brain tissue histograms were significantly lower for individuals with CADASIL than for control subjects. MTR values from NAWM were strongly correlated with the extent of macroscopic lesions and their average MTR. Apart from NAGM, average MTR from all other tissues studied significantly decreased with increasing age, physical disability, and cognitive impairment. CONCLUSIONS: PD lesions of individuals with CADASIL have variable degrees of tissue damage. Brain tissue outside PD abnormalities is also damaged. This study suggests that the extent and the severity of the brain tissue damage are critical factors in determining clinical status in CADASIL.

Age Factors↗