Computed tomography: 3D reconstructions and colour coded discrimination of the dental groups.
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Biomedical subjects
Publications and source records attributed to E A Cabanis.
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The authors introduce the two following papers. A general review of MRI evolution during the ten past years is proposed. Some recent evolutions are emphasized: fast imaging, MR angiography, workstations devoted to 3D reformations and functional imaging are illustrated. The complementary position of CT and MR, and the worldwide machines diffusion are summarized. The authors of following papers are introduced and presented.
Magnetic resonance imaging (MRI) of two pig brains was realized. The animals were placed in the stereotaxic conditions currently used in experiments. To allow the positioning of the animal in the MRI instrument, landmarks were previously traced on the snout of the pig. To avoid movements, animals were deeply anesthetized. MRI were taken in frontal, horizontal and sagittal directions. Afterwards, the brains of the pigs were frozen and cut into sections, frontal for one animal and sagittal for the other. Histologic and MR images were compared. The usefulness of this technique is discussed.
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The authors present the results of a morphometric study of the brain of 7 patients with cat cry syndrome, explored with Magnetic Resonance Imaging (MRI). A method is proposed in order to facilitate the identification of the anatomical slices. A characteristic anomaly is observed as a marked atrophy of the brainstem predominating at the pontine level and associated with a small cerebellum, atrophic middle cerebellar peduncles and cerebellar white matter. This apparently systematized atrophy obvious in children, seems similar to the one observed in patients presenting a olivopontocerebellar atrophy, possibly correlating with disturbance of coordination and developmental delay in motility as observed in these patients. This does not implicate the same subjacent functional neuroanatomical pathways.
Dynamic mode magnetic resonance imaging (DMMRI) allows good visualization of the oculomotor muscles and allows their dimensions to be measured both when they contract and when they relax. The accuracy of this method has been checked and the measurements of the cross section of medial and inferior recti and of superior obliques can be considered to be valid. Measurements of length are inaccurate and the other muscles are not perpendicular to the sectional planes generally used in MRI of the head. By means of a fixation scale situated in the tunnel of the machine, the maximum diameter of medial recti in their thickest part was evaluated in two girls affected by a Stilling Duane retraction syndrome of the left eye. Two direction of the gaze were explored: 25 degrees at the right, then 25 degrees at the left, these angles being obtained by the fixation of particular points of the tunnel scale. The measurements have been made on axial sections, then on coronal sections, both medio-orbital and apical. The first finding is that the diseased medial rectus is much bigger than the healthy one. When relaxed, its thickness is about the same as that of the contracted normal muscle. Coronal orbital cross sections clearly show recession of the belly of the diseased muscle towards the back of the orbit. When contracted it stays in the apical plane and when relaxed in the medio-orbital plane. Lastly the relaxation is much weaker for the pathological muscle than for the healthy one.(ABSTRACT TRUNCATED AT 250 WORDS)
Two models of eye-movements are in competition with each other: the cardanic suspension (Listing law 1845) and the socket-joint (structural-hemispheric theory 1986). The dynamic orbital MRI demonstrates arguments for the latter which is based upon anatomy and physiology.
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MRI sections of the brain in the coronal plane through the line joining the anterior commissure and the mamillary bodies display the constituent parts of the basal forebrain. The visualisation of the septal nuclei and the anterior columns of the fornix show the importance of this plane in the study of behaviour disorders and amnesic syndromes.
A cephalic reference plane is described through the chiasmatic notch and the posterior commissure, which is easily identified on mid-sagittal cuts using magnetic resonance imaging. The horizontal cuts so obtained are almost parallel to the lateral fissure and are perpendicular to the axis of the brain stem.
The authors report their experience of the surgical approach for suprasellar tumors (Jugum or tuberculum sellae meningiomas, 3 cases, and suprasellar craniopharyngiomas, 2 cases) in over than seventy years old patients (71-78 y). A limited craniectomy was performed at the fronto-temporal junction using three adjacent burr-holes. The duramater was cut with an Y-shaped incision. Cerebrospinal fluid was sucked out through a lateral subfrontal route, allowing an easy cerebral collapse in elderly patients, which can sometimes avoid even retraction. Such an supra-orbital craniectomy allowed a subfrontal approach, opening of the sylvian fissure and control of the inter optic, inter carotido-optic and latero-carotidian spaces as well as a good access to the inter pedoncular cistern. In 4 cases the craniectomy was performed after fronto-temporal skin incision, but a trans eyebrow skin incision was used in 1 case. All patients had uneventful postoperative course. Follow-up was from 3 to 5 years. A visual improvement occurred in all cases. Benefits of this surgical method are discussed and compared with use of a bone flap in patients over than 70 years.
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MRI sections of the brain in the coronal plane through the line joining the anterior commissure and the mamillary bodies display the constituent parts of the basal forebrain. The visualisation of the septal nuclei and the anterior columns of the fornix show the importance of this plane in the study of behaviour disorders and amnesic syndromes.
This work deals with dynamic anatomy of human body explored by magnetic resonance imaging (MRI). Recent development of MRI pulse sequences allow very fast data acquisition. Using an 1,5 Tesla system (General Electric--CGR, Signa), different body segments have been explored, in two different ways. The first approach consisted in a cinematographic display of anatomical sections of an articulation obtained in different positions. The result shows the movement of the articulation. The second approach consisted in the examination of a single slice several times, with cardiac synchronization ("gating"). the result is the evaluation of phase desynchronization, measuring the flow directions and the velocity of circulating fluids. The results are shown as a video tape with commentary. It starts with the joints: the ankle, the knee, the wrist, the hand, the cervical spine, de cervico-occipital junction, the temporo protrusion during deglutition and the ocular movements (normal and pathological), according to different planes, are successively proposed. Finally, flow kinetics are shown: cardiac movements and supra-aortic arterial flow, the intracranial cerebro-spinal fluid circulation, in normal and pathologic (intra-cranial hypertension) cases. The exposition is concluded by showing a work in progress on urine flow during micturition.
Proposes and defines a cephalic reference plane that joins the chiamatic notch to the posterior commissure, easily shown on a mid-sagittal cut using magnetic resonance. The horizontal cuts obtained prove to be very close to those oriented according to the lateral fissure, and orthogonal the great axis of the brainstem.
New MR softwares allow a dynamic display of different fonctionnal anatomical regions. This work is a first attempt to visualize the ocular movements. A video tape constitute the support of our results. Technically, the work is performed on a Signa 1,5 T GE CGR System. During each MR acquisition, the subject is asked to fix his gaze successively on each spot of a scale set inside the bore of the magnet. Twenty four images are performed to show the entire lateral course of the globes. The examination time is about half an hour. The video display show the movements of agonist and antagonist muscles, the eyeballs and the optic nerves displacements, in the axial neuro-ocular plane (NOP). Different clinical applications of this new method are discussed (muscular surgery...).
Sagittal sections of the brain-stem made by MRI reveal differences in the angle formed by the medulla and the cord. In order to study the normal mobility of this region of the CNS during flexion and extension of the head, sagittal MRI studies were made in the sagittal plane in 18 young volunteers. The volunteers were in dorsal decubitus with the cervical spine first flexed and then extended, with the movement localized to the cranio-cervical junction as far as possible. T1-weighted sequences were used, with body coils in 16 cases and surface coils in two. Measurements were related to global cranio-cervical range of movement, movement at the cranio-cervical junction and spino-medullary movement. Variations in the depth of the free space in front of the medulla, pons and spinal cord during movement were also noted. We also checked for downward shift of the lower part of the 4th ventricle and modification of the shape of the ventricle during flexion-extension. The global range of cranio-cervical movement was between 31 and 100 degrees (average 63 degrees). The range between the cranium and C1C2 was 4 to 39 degrees (average 19 degrees) and the spino-medullary range was from 1 to 32 degrees (average 14 degrees). During flexion, the free space narrowed in front of the pons 11 times, in front of the medulla 14 times and in front of the cervical cord 11 times. There was a downward shift of the lower part of the 4th ventricle during flexion in 4 cases but no change in shape was noted. Though this study is open to criticism from several aspects, it may be concluded that variations of the spino-medullary angle in the sagittal plane during flexion-extension do occur, that they are closely correlated with movements at the cranio-cervical junction, moves forward during flexion.