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T A Yousry

Publications and source records attributed to T A Yousry.

At least 73 records · Page 4Linked to original sources
PubMed1998

A preliminary study comparing the sensitivity of serial monthly enhanced MRI after standard and triple dose gadolinium-DTPA for monitoring disease activity in primary progressive multiple sclerosis.

We performed this study to evaluate and compare the numbers of total and new enhancing lesions detected on serial monthly brain magnetic resonance imaging (MRI) after the injection of a standard dose (SD) and a triple dose (TD) of gadolinium-DTPA (Gd) in patients with primary progressive multiple sclerosis (PPMS). Every 4 weeks for 3 months and in two separate sessions, MRI scans were obtained from 5 patients with PPMS, 5 (early) and 20 minutes (delayed) after SD (0.1 mmol/kg) or TD (0.3 mmol/kg) Gd injection. In 2 patients, T1-weighted scans with a magnetization transfer pulse (MT) after SD and TD injection were also obtained. There were 13 enhancing lesions (5 of which were new) on the early SD scans, 15 (5 new) on the delayed SD scans, 17 (6 new) on the early TD scans and 18 (7 new) on the delayed TD scans. TD MRI scans detected more enhancing lesions than SD scans in 3 patients (two of them were those with the lowest disability). The application of the MT pulse did not change the numbers of enhancing lesions seen after the injection of SD and TD of Gd in the remaining two patients. No side effects were reported and no significant changes in blood test parameters were found throughout the study. Our results suggest that serial monthly TD MRI, delayed scanning, MT T1-weighted scans or their combination, although safe, have a limited role for monitoring disease evolution in patients with PPMS.

Adult↗
PubMed1998

Common variable immunodeficiency leading to spinal subacute combined degeneration monitored by MRI.

A patient is reported on with a common variable immunodeficiency syndrome (CVID), in whom chronic gastritis with antibodies against parietal cells and a cytomegalovirus associated enteritis led to vitamin B12 deficiency with consecutive subacute combined degeneration of the spinal cord. The resulting medullary changes, most probably representing demyelination, were visualised with MRI. The effects of treatment were also monitored over three years by MRI and clinical examination. The resolution of the MRI changes correlated with clinical improvement of the patient's signs. In the medical literature only five cases of vitamin B12 related spinal cord changes have been identified by MRI; none was caused by a CVID syndrome.

Autoimmune Diseases↗
PubMed1998

The effect of cross-talk on MRI lesion numbers and volumes in multiple sclerosis using conventional and turbo spin-echo.

We measured and compared lesion numbers and volumes present on brain magnetic resonance imaging (MRI) scans of patients with multiple sclerosis (MS) acquired with contiguous (scheme A) and interleaved (scheme B) slice acquisition, to evaluate whether there was a gain in sensitivity using the second pattern of acquisition and whether this counterbalanced the doubled acquisition time. Conventional spin-echo (CSE) sequences were performed for eight patients and turbo spin-echo (TSE) sequences for ten. Acquisition scheme B detected 3.8% more lesions than acquisition scheme A (the increase was 3.1% for CSE and 4.5% for TSE). These differences were not statistically significant. No significant difference in lesion numbers was found when different lesion locations were also considered. Lesions volumes were significantly higher when scheme B was used (P = 0.024). This was due to higher lesion volumes on TSE images (P = 0.006), especially on even-numbered slices (P = 0.008). Inter-slice cross-talk has a negligible effect on lesion numbers and volume estimates in MS for CSE sequence, whilst it cannot be neglected when TSE sequences are used to measure MS lesion volume.

Adult↗
PubMed1998

Increased spatial resolution using a three-dimensional T1-weighted gradient-echo MR sequence results in greater hypointense lesion volumes in multiple sclerosis.

PURPOSE: Our goal was to evaluate whether improved spatial resolution of MR images results in the detection of higher volumes of hypointense lesions in patients with multiple sclerosis (MS). METHODS: A magnetization-prepared rapid acquisition gradient-echo (MP-RAGE) sequence with subsequent reconstruction of axial sections with 5-, 3-, and 1-mm thickness and a dual-echo sequence were obtained in 16 patients with relapsing-remitting or secondary-progressive MS. The volumes of MR imaging abnormalities present on each of these studies were measured using a semiautomated segmentation technique based on local thresholding. The hypointense lesion volumes seen on the three reconstructed MP-RAGE sets of images were compared using the Friedman test and correlated with the hyperintense lesion volume on proton density-weighted images and with scores on the Expanded Disability Status Scale using Spearman's rank correlation coefficient. RESULTS: The median volume of hypointense lesions increased from 1.2 mL (range, 0 to 14.9 mL) on the 5-mm-thick MP-RAGE images to 1.7 mL (range, 0 to 15.8 mL) on the 3-mm-thick images, and to 1.9 mL (range, 0 to 16.2 mL) on the 1-mm-thick images. The hypointense lesion volumes measured on the three MP-RAGE images correlated significantly with the degree of disability, whereas this correlation was not significant with the T2-weighted lesion load. CONCLUSION: Our findings indicate that a significant increase in the volume of potentially disabling MS lesions is observed when obtaining MR images with thin sections.

Adult↗
PubMed1998

Functional magnetic resonance imaging in multiple sclerosis.

Functional magnetic resonance imaging (fMRI) is a method that combines high anatomical spatial resolution with the ability to localise function. Visual and motor systems are among those that have received most attention. Yet the clinical application is still limited. Recently, some investigators applied fMRI to study patients with multiple sclerosis. Patients with partial motor weakness disclosed a larger area of cortical activation bilaterally by contrast with healthy volunteers when using the affected arm, whereas patients with optical neuritis disclosed a smaller area of activation, when stimulating the affected eye. These results show that different systems might react heterogeneously.

Brain↗
PubMed1998

Quantitative assessment of magnetic resonance imaging lesion load in multiple sclerosis.

Changes of lesion load on yearly conventional spin echo (CSE) T2-weighted scans of the brain from patients with multiple sclerosis, measured using computer assisted techniques, are used to monitor long term disease evolution, either natural or modified by treatment. Although lesion load measurements have several advantages over clinical measures of outcome (they provide a more objective and sensitive measure of disease evolution, which has a linear distribution and a more strict relation with the underlying pathology), the poor correlation between changes of lesion load and changes of disability is of concern when using such an approach for monitoring multiple sclerosis trials. In this review, the main sources of variation in T2 lesion load from brain MRI of patients with multiple sclerosis will be considered, along with possible strategies to, at least partially, overcome them. Also, some of the newer fully automated techniques to segment multiple sclerosis lesions, which have been validated against manual outlining, and a recently developed coregistration technique are presented. It is hoped that a more reliable and standardised approach to lesion load measurements in multiple sclerosis will lead to better correlation with clinical disease course, to a higher confidence in the results of trials, and to reduced numbers of scans needed to conduct the trials, thus improving cost efficiency and reducing discomfort of the patients.

Brain↗
PubMed1997

[An unusual combination of carotid artery-cavernous sinus fistula and sinus thrombosis. Successful therapy with anticoagulation].

Dural carotid cavernous fistulas (DCCF) can be associated with venous thrombosis. We report on a rare case of a patient who developed a venous infarct, which was diagnosed on CT and MRI. The DCCF predominantly drained through a frontobasal cortical vein into the superior sagittal sinus. The shunt volume was small and was therefore thought not to be sufficient to explain the massive ocular signs, such as severe exophthalmus and reduction of visual acuity. We therefore postulated a venous congestion owing to a secondary spontaneous venous thrombosis of the draining venous pathways to be responsible for the ocular signs. Under anticoagulative medication, the patient's signs and symptoms improved gradually. Control angiography after 3 months showed that the DCCF had disappeared. In the presence of DCCF, anticoagulation should always be considered when a venous thrombosis is suspected.

Arteriovenous Fistula↗
PubMed1997

[Bleeding atheroma. A nuclear magnetic resonance tomography differential diagnosis of dissection of the carotid artery].

Improved methods of imaging the cerebral vascular system have increased the detection of traumatic or spontaneous dissection of the vertebral and carotid arteries. Especially MRI allows direct demonstration of intramural hematomas that are a sign of dissection of the vessel wall. We report on a patient who had an acute onset of dysarthria and monocular blurred vision, which recurred several times. Doppler ultrasound showed stenosis in both internal carotid arteries with reduced velocity of the flow; angiography confirmed the stenosis, showing a long stretch of stenosis (70%) of the right and a short stretch of stenosis (60%) of the left internal carotid arteries. MRI demonstrated a narrowing of the lumen by an intramural mass, whose signal characteristics were typical for blood. The MRI findings were thus consistent with the diagnosis of a spontaneous dissection of the carotid arteries. Since the Doppler ultrasound follow-up showed no change during the following 3 days, we interpreted the MRI findings as an indication of bleeding in an atheroma. The carotid disobliteration, performed first on the left side and later on the right side, confirmed this interpretation. Since stenosis due to a fissuring atheroma or bleeding in an atheroma requires different therapy than a dissection, it is thus important to consider the possible differential diagnosis in interpreting the MRI.

Arteriosclerosis↗
PubMed1997

Localization of the motor hand area to a knob on the precentral gyrus. A new landmark.

Using functional magnetic resonance imaging (fMRI) we have evaluated the anatomical location of the motor hand area. The segment of the precentral gyrus that most often contained motor hand function was a knob-like structure, that is shaped like an omega or epsilon in the axial plane and like a hook in the sagittal plane. On the cortical surface of cadaver specimens this precentral knob corresponded precisely to the characteristic 'middle knee' of the central sulcus that has been described by various anatomists in the last century. We were then able to show that this knob is a reliable landmark for identifying the precentral gyrus directly. We therefore conclude that neural elements involved in motor hand function are located in a characteristic 'precentral knob' which is a reliable landmark for identifying the precentral gyrus under normal and pathological conditions. It faces and forms the 'middle knee' of the central sulcus, is located just at the cross point between the precentral sulcus and the central sulcus, and is therefore also visible on the cortical surface.

Aged↗
PubMed1997

Postoperative spiral computed tomography and magnetic resonance angiography after aneurysm clipping with titanium clips.

OBJECTIVE: To reduce morbidity and mortality after subarachnoid hemorrhage, it is imperative to evaluate the results of the surgical treatment of cerebral aneurysms. We investigated the usefulness of spiral computed tomography (CT) and magnetic resonance angiography as postoperative control examinations after cerebral aneurysms were clipped with titanium clips. METHODS: Eleven patients with 13 treated aneurysms were studied prospectively with postoperative digital subtraction angiography, spiral CT, and magnetic resonance angiography. The occlusion of the dome of the aneurysm, the presence of a remnant of the neck, the patency of the parent vessels and other major vessels, and the presence of vasospasm were investigated. RESULTS: The different parameters could all be well evaluated by postoperative spiral CT. The artifacts caused by the titanium clips, although relatively small compared with artifacts from other clips, precluded evaluating the dome and the neck of the aneurysm with magnetic resonance angiography. CONCLUSION: In our opinion, spiral CT promises to become a valuable aid in in the postoperative evaluation of clipped aneurysms, and we recommend its routine performance. Postoperative digital subtraction angiography remains the gold standard and has to be performed when spiral CT reveals abnormalities, when the neck of the aneurysm cannot be evaluated because the clip overlays it, or when, intraoperatively, imperfect clipping is suspected and intraoperative angiography cannot be performed.

Adolescent↗
PubMed1997

Preoperative activation and intraoperative stimulation of language-related areas in patients with glioma.

OBJECTIVE: Evaluation of the accuracy of preoperative localization of language-related cortex by magnetic resonance imaging-guided positron emission tomography. METHODS: Patients with gliomas in the left dominant hemisphere were examined preoperatively with magnetic resonance imaging-guided positron emission tomography and intraoperatively by electrical stimulation of cortex. RESULTS: A verb generation task yielded more intense and better lateralized local increases of cerebral blood flow in the positron emission tomographic examination than did a naming task. Significant correspondence of preoperative and intraoperative findings was observed for the verb generation task. Cortical sites with aphasic disturbance during electrical stimulation had a significantly higher cerebral blood flow increase during preoperative activation than did sites without intraoperative language impairment. Areas with cerebral blood flow increases above an optimum threshold had 73% sensitivity and 81% specificity to predict aphasic disturbance during intraoperative stimulation. CONCLUSION: The data suggest that with further technical improvements, imaging of language function may become a preoperative diagnostic tool for patients with tumors close to language-related brain structures.

Adult↗
PubMed1997

Inter-rater variability in reporting enhancing lesions present on standard and triple dose gadolinium scans of patients with multiple sclerosis.

In this study we evaluated and compared the inter-rater variabilities in detecting enhancing lesions in patients with MS after injection of a standard dose (s.d.) and a triple dose (TD) of gadolinium (Gd). Enhanced magnetic resonance imaging (MRI) were obtained in 15 patients, consisting of T1-weighted images 5 to 7 min after the injection of the s.d. (0.1 mmol/kg) of Gd and, after an interval of 6 to 24 h, 5 to 7 min after the injection of the TD (0.3 mmol/kg). An additional scan 1 h after the TD injection (delayed scanning-DS) was obtained in 11 patients. The scans were independently evaluated in a random order by four observers. Lesions were counted and scored according to size and location. The level of inter-observer observer concordance was very high for reporting the total numbers of enhancing lesions, their sizes and sites for the three experimental conditions. No significant differences were found in inter-observer variability in reporting the total number of enhancing lesions and their location in different brain sites in the three conditions. Our data indicate that the gain in sensitivity in detecting enhancing lesions in MS with the TD is not counteracted by a loss in reproducibility. This is important in planning clinical trials in which the number of enhancing lesions is used as a measure of outcome.

Brain↗
PubMed1997

Interscanner variation in brain MRI lesion load measurements in MS: implications for clinical trials.

We evaluated the effect of interscanner variation on brain MRI-measured lesion volumes and measurement reproducibility in MS. Twenty clinically definite MS patients were each scanned on two or three scanners (a total of 14 scanners were used). In addition, a formalin-fixed MS brain was studied on eight scanners from different manufacturers and with different field strengths. For the formalin-fixed MS brain, on each machine we obtained two scans with slice thicknesses of 5 and 3 mm. Only 5-mm-thick slices were obtained from patients. The lesion volume present on each scan was evaluated three times by a single observer in random order, using a local thresholding technique. In two groups of eight patients scanned on machines with different field strengths, the mean lesion volumes present on scans obtained at 1.5 T were significantly higher than those measured on scans obtained with machines operating at 0.5 and 1.0 T (p < 0.01). When a single observer repeatedly evaluated the same scan, a median introbserver agreement of 98.7% (95% CI, 97.9 to 99.1) was achieved. However, when the observer evaluated the scans from different MRI scanners, the agreement (an interscanner agreement) fell to 91.1% (CI, 90.2 to 94.1). When only scanners operating at 1.5 T were considered, the median interscanner agreement was 96.7% (CI, 95 to 97.5). Also, for the formalin-fixed MS brain, the intraobserver agreements obtained with both slice thicknesses were significantly higher than the corresponding interscanner agreements. The interscanner agreement, but not the intraobserver agreement, obtained with a slice thickness of 3 mm was higher than that obtained with a slice thickness of 5 mm. Our results indicate that lesion volume measurements in MS are influenced significantly by the use of different MR scanners and that a patient included in a serial study should be always scanned with the same MR machine using 3-mm thick slices.

Adult↗
PubMed1997

Improving interobserver variation in reporting gadolinium-enhanced MRI lesions in multiple sclerosis.

Gadolinium-enhanced MRI is a sensitive and objective means to monitor disease activity in multiple sclerosis (MS). We evaluated the interobserver agreement and the value of observer training in reporting enhancing lesions from serial MRI. Scans of 16 MS patients were evaluated by five inexperienced and five experienced observers before and after consensus formation and training. The number of lesions at baseline, and the number of new and persistent lesions at follow-up were scored. For each condition, weighted kappa values (kappa) and the mean average difference to the median (MADM) scores were calculated. Without training, the experienced readers showed good agreement on number of lesions at baseline and new lesions at follow-up, and moderate agreement for persistent lesions. The inexperienced readers showed poor agreement for baseline and persistent lesions, and moderate agreement for new lesions. After training, both groups reported lower absolute numbers of lesions, especially the inexperienced readers. The experienced readers showed good agreement for all lesion types, the inexperienced readers showed agreement for baseline and new lesions, and agreement was moderate for persistent lesions. In both groups MADM scores were < 0.72 for baseline and new lesions, but > 1.2 for persistent lesions. Interobserver agreement is improved by training, especially in inexperienced readers. Interobserver agreement in reporting gadolinium-enhanced lesions is high, which validates the use of serial, enhanced MRI as an outcome parameter in treatment trials in MS.

Analysis of Variance↗
PubMed1997

Comparison of MR pulse sequences in the detection of multiple sclerosis lesions.

PURPOSE: To compare the sensitivity of conventional spin-echo, fast spin-echo, fast fluid-attenuated inversion recovery (FLAIR), and turbo gradient spin-echo MR sequences in the detection of multiple sclerosis lesions. METHODS: Conventional spin-echo, fast spin-echo, fast FLAIR, and turbo gradient spin-echo sequences were performed on a 1.0-T MR imager in seven patients with clinically definite multiple sclerosis. The images in each sequence were evaluated by two raters and consensus was reached by agreement. RESULTS: In comparing conventional spin-echo with fast spin-echo sequences, five lesions were seen only by conventional spin-echo and 63 were seen only by fast spin-echo; in comparing conventional spin-echo with fast FLAIR sequences, 18 lesions were seen only by conventional spin-echo and 109 only by fast FLAIR; in comparing conventional spin-echo with turbo gradient spin-echo sequences, 51 lesions were seen only by conventional spin-echo and seven only by turbo gradient spin-echo; in comparing fast spin-echo with fast FLAIR sequences, 45 lesions were seen only by fast spin-echo and 52 only by fast FLAIR. CONCLUSION: Fast spin-echo and fast FLAIR sequences improve the sensitivity of MR imaging in the detection of multiple sclerosis lesions with reduced acquisition time as compared with conventional spin-echo sequences. These sequences should therefore be considered for serial studies in patients with multiple sclerosis. The sensitivity of turbo gradient spin-echo was inferior to the other sequences, but its reduced acquisition time could make this technique the ideal choice for patients who cannot tolerate longer examination times.

Diagnosis, Differential↗
PubMed1996

Spinal cord MRI in multiple sclerosis with multicoil arrays: a comparison between fast spin echo and fast FLAIR.

OBJECTIVES: To compare the sensitivity of fast spin echo (FSE) and of fast fluid attenuated inversion recovery (fast FLAIR) in detecting spinal cord lesions in multiple sclerosis. METHODS: With a 1.5 Tesla machine and a multicoil receiver array, FSE images (with two different pixel sizes) and fast FLAIR images of the spinal cord were obtained from 13 patients with multiple sclerosis. RESULTS: Twenty three lesions (10 cervical, 12 thoracic, and one lumbar) were found in seven patients (54%) using FSE with the larger pixel size. Seventeen lesions (seven cervical and 10 thoracic) were detected in the same seven patients using FSE with smaller pixel size. Nine lesions (five cervical and four thoracic) were found using fast FLAIR in six patients (46%). All the lesions found using fast FLAIR were detected using the other two techniques and all the lesions detected by FSE with smaller pixel size were detected using FSE and greater pixel size. CONCLUSION: Fast FLAIR sequences detect substantially fewer cord lesions in patients with multiple sclerosis.

Adult↗
PubMed1996

The central sulcal vein: a landmark for identification of the central sulcus using functional magnetic resonance imaging.

The authors evaluated the anatomical location of the central sulcus (CS) in 24 cerebral hemispheres (eight in which tumors were located centrally, 16 in controls) using: 1) classic anatomical landmarks seen on magnetic resonance (MR) imaging (24 hemispheres); 2) functional MR imaging (24 hemispheres); and 3) intraoperative electrical stimulation mapping (eight hemispheres). On MR imaging the CS was identified with certainty in 79% of hemispheres (four of eight in patients, 15 of 16 in controls). Functional MR imaging identified a parenchymal "motor hand area" in only 83% (20 of 24 hemispheres; five of eight in patients, 15 of 16 in controls); this area was located in the precentral gyrus in 16 (80%) of 20, additionally in the postcentral gyrus in 10 (50%) of 20, and exclusively in the postcentral gyrus in four (20%) of 20. In contrast, functional MR imaging detected one to three sulcal veins presumably draining blood from the adjacent motor hand area in 100% (24 of 24) of the hemispheres studied, and anatomical MR imaging and intraoperative mapping localized these veins in the CS. It is concluded that sulcal veins lying deep within the CS: 1) drain activated blood from the adjacent pre- or postcentral cortex during performance of a motor hand task; 2) can be identified easily with functional MR imaging; and 3) are an anatomical landmark for noninvasive identification of the CS and thus the sensorimotor strip. The detection of these veins provides a more consistent landmark than the detection of parenchymal motor areas by functional MR imaging; this technique may be used when classic anatomical landmarks fail to identify the sensorimotor strip.

Adult↗