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Biomedical subjects

A Abanou

Publications and source records attributed to A Abanou.

15 recordsLinked to original sources
PubMed2005

MR tractography with diffusion tensor imaging in clinical routine.

Using MRI, we demonstrated that the depiction of the cerebral white matter fiber tracts has become a routine procedure. Diffusion tensor (DT) sequences may be analyzed with combined volume analysis and tractography extraction software, giving indirect visualization of white matter connections. We obtained DT data from 20 subjects with normal MR imaging and five patients presenting cerebral diseases such as brain tumors, multiple sclerosis and stroke, with five patients explored on two different MR scanners. Data were transferred to dedicated workstations for anatomical realignment, determination of voxel eigenvectors and calculation of fiber tract orientations in a region of interest. In all subjects, axonal directions underlying the main neuronal pathways could be delineated. Comparisons between diseased regions and contralateral areas demonstrated changes in voxel anisotropy in injured regions, revealing possible preferential fiber orientations within diffuse T2 hyperintensities. Rapid data processing allows imaging of the normal and diseased fiber pathways as part of the routine MRI examination. Therefore, it appears that whenever white matter disease is suspected a tractography can be performed with this fast and simple method that we proved to be reliable and reproducible.

Adult↗
PubMed2005

Acute demyelination: an insight into the effect of mitoxantrone on CNS lesions.

We report the cases of 2 severely disabled patients with large inflammatory lesions suggestive of demyelination treated with mitoxantrone. Clinical condition was improved and brain lesions volume was reduced. On serial MR spectroscopy, there were variations in peaks between 0.9 and 1.4 ppm, suggestive of free lipids and amino acids. These variations may represent neurochemical markers of clinical recovery of large inflammatory lesions in multiple sclerosis.

Acute Disease↗
PubMed2003

[Tractography of the visual pathways: routine examination in magnetic resonance imaging].

Water diffusion analysis in magnetic resonance imaging (MRI) provides an elective visualization of fiber tract orientations in cerebral white matter, especially for optic tracts. We explored 25 patients from 18 to 45 years of age, with normal MRI in 20 subjects, and radiological anomalies in five. On a 1.5 Tesla MRI apparatus, diffusion tensor acquisitions were performed in 5 minutes 58 seconds with an EPI Single Shot sequence covering the entire brain. Image displacements were precluded by patient information and adequate fixation, then digitally corrected on workstations. Volume merging and fiber tract extraction were achieved using dedicated software (Volume-One and dTV). A directional depiction was obtained for all areas in the white matter, in particular for white matter junctions. Coming from the lateral geniculate body, the optic tracts were directed posteriorly toward the occipital cortex, with numerous connections to extrastriate associative areas, and through the corpus callosum and the fornix. Diffusion tractography requires optimization of volume displacements, before and secondary to MRI acquisitions. Our diffusion tensor acquisition, with image optimization in a short-duration sequence can be routinely applied to all patients, for a specific analysis of functional connections between cortical areas of cerebral white matter.

Adolescent↗
PubMed2001

Correlating multiple MRI parameters with clinical features: an attempt to define a new strategy in multiple sclerosis.

MRI is the most powerful imaging technique in managing patients with suspected or confirmed multiple sclerosis (MS). However, conventional MRI variables show nonspecific abnormalities weakly correlated with clinical progression of the disease. New techniques, now routinely available, offer better characterisation of the pathophysiology. We combined conventional MRI, including lesion load, contrast enhancement and "black holes" with magnetisation transfer and diffusion-weighted imaging and localised proton MR spectroscopy (MRS) to study their relationship with disability, course and duration of MS. The variables that were the most significantly linked to the course of the disease (relapsing remitting versus secondary progressive) were lesion load, mean overall magnetisation transfer ratio and apparent diffusion coefficient (MGADC), the percentage of ADC in (PADCIMD), and out of (PAD-COMD) modal distribution, and the ratio N-acetylaspartate and creatine-containing compounds on MRS of the centrum semiovale. MGADC and PADCIMD were the independent factors most related to disability and duration of disease. Combining MRI techniques is clinically relevant and feasible for studies of MS and may be applied to other diseases of the central nervous system.

Adult↗
PubMed1999

Normal-appearing white matter in optic neuritis and multiple sclerosis: a comparative proton spectroscopy study.

We investigated neurochemical abnormalities in the normal-appearing white matter (NAWM) on MRI of patients with optic neuritis (ON) and compared them to those of patients with multiple sclerosis (MS). Patients with ON (42) were classified into three groups according to abnormalities on brain MRI. Patients with MS (55) were divided in two groups: relapsing remitting MS (RRMS) and secondary progressive MS (SPMS). All patients underwent MRI of the brain and localised proton magnetic resonance spectroscopy (MRS) of NAWM. The results were compared to those of 15 controls. Patients with MS had significant abnormalities compared with controls and with patients with ON. Patients with RRMS and those with ON had comparable MRS parameters, while patients with SPMS had significant spectroscopic abnormalities in comparison with controls, but also with patients with RRMS. These changes consisted of a decrease in N -acetylaspartate, a neuronal marker, which may reflect axonal dysfunction and/or loss. MRS abnormalities were detected in 14 patients with ON (27 %). The main abnormalities consisted of a decrease in N -acetylaspartate, an increase in choline-containing compounds at long echo times, and the presence of free lipid peaks at short echo times. MRS of the NAWM on MRI may prove useful for detecting neurochemical brain abnormalities in ON not visible on MRI.

Adult↗
PubMed1997

Minimal surface: a useful paradigm to describe the deeper part of the corpus callosum?

The aim of this magnetic resonance imaging study was to find a geometrical characterization of the deeper part of the corpus callosum. Its shape was studied in 12 middle-aged persons free of white matter pathology. Profiles of curvatures were measured showing that this surface was close to a minimal one, especially at the genu and near the splenium. To assess the effect of a white matter pathology on these geometrical features, the same measurements were performed in an extra group of nine patients with definite multiple sclerosis. The hypothesis of curvatures profiles parallelism for the two groups could be rejected at the 0.05 confidence level for the mean curvatures but not for the Gaussian ones. Curvatures profiles may give indications on balance between the cortex and the fiber bundles growth rates during the development and on large scale modifications co-occurring with multilocular white matter pathologies.

Adult↗
PubMed1984

The accessory middle cerebral artery (AMCA). Diagnostic and therapeutic consequences.

The existence of the accessory middle cerebral artery (AMCA) is a rare anatomical variation with an estimated incidence of 0.31%. The embryological development of this artery is unknown. Three anatomical subtypes are described: in the type 1 variety the AMCA arises from the internal carotid artery; in the type 2, the AMCA originates from the proximal part of the anterior cerebral artery; in type 3, the AMCA arises from the distal part of the anterior cerebral artery. The use of endovascular techniques to treat cerebral vascular malformations requires knowledge of the anatomical subtype of AMCA and the brain regions it supplies (cortex, basal ganglia).

Adult↗
PubMed1984

Radiological anatomy of the vascularization of cranial dural arteriovenous malformations.

Knowledge of the radiological anatomy of the cranial dural vascularization allows a flexible and appropriate approach to the pretherapeutic investigation of cranial dural arteriovenous malformations. The variability of the origin of these arteries requires that several possible sources of vascular supply be investigated - internal carotid, internal maxillary, ascending pharyngeal, occipital and vertebral - and that each of their meningeal branches be known in detail. Finally, familiarity with the radiological anatomy of these vessels allows one to identify on routine angiography those vessels that may be a source of risk when performing techniques of endovascular therapy (pedicles supplying the cranial nerves, internal carotid and vertebral anastomoses). Each foramen at the base and vault of the cranium contains an artery to the dura mater. Accordingly, very precise topographical study, in particular of the cavernous region, can be made.

Angiography↗
PubMed1983

[Computed x-ray tomographic aspects of intra-orbital hydatid cyst. Apropos of 10 cases].

Echinococcus taenia occurs in human accidentally after contamination by infected dust of dog. Although it may localize in all parts of the body as a hydatic cyst, liver, lung and kidney are the most frequent sites. Intra-orbital localization is rare since all statistical studies estimate it to be one per cent of orbital tumours. Using computerized axial tomography (C.A.T. Scanner) ten cases of intra-orbital hydatic cyst originating from Algiers, Tunis Hospitals and C.N.O. des Quinze-Vingts of Paris were studied. The inclusion of C.A.T. scanning in the orbital evaluation enables more positive preoperative diagnosis and facilitates the choice of the most efficient surgical approach.

Adult↗
PubMedDate not supplied

[Etiologic diagnosis of oculomotor paralysis by computerized tomography: a statistical approach. Apropos of 472 cases].

Among 4,538 neuroradiology cases gathered at the NOHC of the XV-XX, an oculomotor paralysis is the 3rd (37.65%) clinical circumstances justifying a computerized tomography (directional plane by the neuro-ocular plane or PNO). The interpretation of the investigations requires to index them in 7 groups of items, therefore a computerized access follows (cross-sorting data). The injury of the VI overcomes (39.61%) followed by the one of the III (33.68%), and the IV (6.35%). In spite of limitations, the study puts forward and debates about etiological frequencies sometimes different from those in the literature.

Adolescent↗
PubMedDate not supplied

[Tomodensitometry of severe acute pancreatitis].

90 computed tomographic examinations were performed to 57 patients referred at Hospital Saint-Louis for an acute pancreatitis. 32 patients were operated or autopsied. Among these 32 patients, 19 patients had 21 examinations before surgery or autopsy; the other 13 patients had their computed tomographic examinations after one or more surgical procedures. During a severe acute pancreatitis the pancreas is always large either locally or diffusely. A pancreatic reaction is visible around and possibly at distance of the pancreas. When extraluminal gas is visible (3/5) it signifies gangrenous pancreatitis but it is necessary to eliminate a digestive fistulous tract and/or a communication between a pseudocyst and the digestive tract. Except gangrenous it is not possible to precise the nature of pancreatic reaction. The diagnosis of pseudocyst was easy 9/10, difficult 1/10; we did a false positive diagnosis of pseudocyst. Computed tomography and ultrasounds were compared in ten patients for the search of gallbladder lithiasis. Computed tomography can show large and small (2/4) biliary calculus in the gallbladder that cannot be shown by ultrasounds. A normal pancreas in a normal retroperitoneal space exclude the diagnosis of a severe acute pancreatitis. CT aspects of acute pancreatitis must be considered as a good diagnostic test of an acute pancreatitis.

Acute Disease↗