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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.

MR T2 Weighted sequences on the brain demonstrate disseminated "high signal zones" (HSZ) in patients with Multiple Sclerosis; these morphological alterations are corresponding to the plaques. From the very beginnings of MR in 1981, everybody recognizes the main importance of this fact. MR appears as the most sensible exploration in patients with M.S. But the signal alteration is not specific; the clinical considerations and the evolution are requested. The aim of this work is to give a reference tool for evolutive evaluation of the disease. A work station with a specially developed software are presented. The HSZ thresholding is partially automatic. The edition of a cerebral mapping is developed. These results are discussed.

We report a case of diffuse retinoblastoma in a 6 years old boy. The diagnosis should be suspected in front of the very evocative clinical picture itself. The aspect of the tyndall phenomenon, and of the convex pseudo-hypopyon, with iris pearls and nodules, together with a peripheral, imprecisely limited, retinal mass, non calcified on ultrasonographic examination, are typical. Aqueous paracentesis shows increased levels of Lactic Dehydrogenase (LDH), but most of all the cytologic examination confirms the diagnosis. The only treatment is enucleation. The clinical picture which may simulate uveitis, especially as this particular type of retinoblastoma has a late onset.

C.T. exploration by N.O.P. in vivo of a Macaca's head is compared with man. The N.O.P. was recognized from many works (E.A.C.). It permitted a biometric approach and very precise morphologic study of the brain and the face. For the first time, it allows comparisons between monkey and man, at different ages.

Compared with malignant neoplasms of the chest, benign tumours are quite rare; cylindroma (or salivary gland adenoma) is exceptional. The apparent histological benignancy belies its high potential for invasiveness. This can, in some cases, lead to extensive, non-conservative surgery. By a different approach in the imaging of the chest, Magnetic Resonance Imaging in this condition may provide an accurate pre-operative assessment. We present a case in which MRI provided the information necessary for the surgical approach, and describe its accuracy and the results obtained.

In an attempt to determine factors of predictive value in HIV (human immuno-deficiency virus) seropositive patients, particular attention was payed to symptoms indicating early involvement of the central nervous system (CNS). A cohort of healthy carriers was thus constituted. Follow-up will be carried out every six month including clinical, biological as well as CNS imaging by NMR. Among the first 15 of them, abnormalities could be observed in 4 individuals. Lesions consisted in nodules of high signal in T2 which were localized either in the white matter or thalamic nuclei. No relationship could be demonstrated between the existence of these lesions and various criteria such as age, sex, risk factors and T4 cells count. Such lesions appeared similar to the localizations observed in multiple sclerosis or to the scars of limited vascular accidents. The nature of these lesions is not clear. They certainly indicate early involvement of CNS after primary infection by the HIV virus. They may either represent sequellae of this primary infection or early alterations announcing developing encephalopathy.

Radiological technique in the investigation of the lacrimal system has greatly benefited from various advances in radiology; techniques of catheterisation, contrast media, seriography, subtractions, associated complex tomography (dacryocystotomography), tomodensitometry. To these may be added the dynamic nature of isotope studies (cinegammadacrycystography). These different techniques may be used in the precise analysis of the morphology of the lacrimal system, from the canaliculi to the meatuses. After reviewing normal radiological anatomy, the authors describe morphological abnormalities, according to different forms of obstruction, according to their site. This morphological discovery requires possible changes in technique (additional tomography, for example). The quality of the preoperative morphological exploration influences the quality of the therapeutic results obtained.

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.

A patient with migraine who had a permanent visual field defect was studied by angiography and CT scan. He also had a tomographic study of cerebral blood flow (CBF) and oxygen extraction fraction (EO2) using the non-invasive continuous oxygen-15 (15O) inhalation technique. Angiography was normal. CT scan revealed an area of decreased density with contrast enhancement suggestive of a recent infarct in the left occipital lobe. The 15O inhalation technique showed a decrease in CBF and EO2, typical of recent infarcts, in the corresponding area, an increase in CBF with normal EO2 in the left temporal lobe, and a decrease in CBF with increased EO2 in the right occipital cortex. These findings illustrate the unusual nature and extent of the ischemic process underlying migrainous cerebral infarction.

To better understand the pathophysiologic correlates of the computed tomographic (CT) scan changes seen in recent cerebral infarction, 17 patients (20 studies) underwent both x-ray transmission and positron emission CT investigations within 18 days after clinical onset of complicated ischemic stroke in the internal carotid artery territory. The density changes before and after contrast study measured within the CT lesion were correlated to the local cerebral blood flow (CBF), oxygen utilization (CMRO2), and oxygen extraction fraction (OEF) measured with the oxygen-15 steady-state positron technique. Statistically significant linear correlations were found between hypodensity and CBF, hypodensity and CMRO2, and contrast enhancement and CBF, such that the more CBF and CMRO2 were depressed, the more marked was the hypodensity; and the more CBF was elevated, the more marked was the contrast enhancement. Although marked contrast enhancement was associated with decreased OEF (luxury perfusion), it was only rarely associated with increased CBF. Various hypotheses are discussed to explain these findings.

The "Atlas of cross-sectional orbito-cephalic anatomy in the neuro-ocular plane" does exist (now in press). The authors submit the main clinico-anatomical correlations observed. We will remind you that the "neuro-ocular plane" (N.O.P.) is defined as the C.T. plane of cephalic orientation comprising "both lenses, optic nerve heads and optic canals in the primary position of gaze". The more informative anatomical, radiological and anthropological data that could derive from the N.O.P. are stressed; first, we will evaluate the validity of our work and the problems we had while building the atlas; then we will describe briefly the position of this cephalic orientation plane as compared to other planes (specifically the anthropological baseline, the orbito-meatal line, the vestibular orientation etc...) previously described. Finally, we will end our discussion by giving the anatomical correlations obtained in the N.O.P.: this plane would best include all the visual pathways starting "from the cornea to the calcarine fissure"; it would also reflect the same orientation of the temporal horn of the lateral ventricle as well as the orientation of the lateral fissure. Much more, the orthogonality of this cephalic orientation to the direction of the brainstem is demonstrated, enhancing the accuracy of the three dimensional approach in the evaluation of the orbito-cephalic anatomy and diseases, as actually completed with C.T. and N.M.R. imaging, at the Centre National d'Ophtalmologie des XV-XX in Paris.

Four observations of spinal forms of multiple sclerosis (MS) have been studied by Magnetic Resonance Imaging (MRI) (Magniscan Thomson CGR 0,15 and 0,5 T). They concerned 3 females and 1 male, aged between 29 and 60. Evolution of MS varied between 1 year and 9 years. There were no familial story of neurological illness; there were no signs and symptoms of visual, oculo-motor, labyrinthic and cerebellar disorders in the past. VEP were abnormal in 2 cases (no 1, 3), BAEP in 1 case (no 2). CSF examination showed increased gamma globulins with an oligoclonal pattern in 2 cases (no 3,4). CT Scan performed with iodine contrast injection was normal in 3 cases (no 2,3,4). In all the cases, MRI using T2 weighted-SE sequences, showed high signal lesions in the white matter of the brain and/or the cerebellum, and periventricular patchy white matter lesions. It seems to be no relationship between the duration of MS and the number of abnormal high signals areas, but more important series are necessary to confirm or not such a result. These lesions seem to be without aetiological specificity. They have to be discussed according to the clinical biological, electro-physiological data and sometimes others neuroradiological procedures.

After the description of the normal head anatomy in MRI and its exploration plans, the images observed in benign and malignant tumours of the brain, in cerebral ischaemic attacks, in the diseases of the orbit, face and skull base, are considered. The limits and present indications of the technique are defined.

One hundred hematomas were examined by magnetic resonance imaging (MRI) at 0.15 T, all explored in SEpT1 and most in SEpT2. The number of cases examined in the acute phase during the first 48 hours was low: 8 cases. At this SEpT1 period the hematoma appears of elevated signal with good muscle contrast but without contrast in hepatic and cerebral parenchyma. In a weighted T2 sequence, the intense signals of cerebral edema and plasma or serum enables detection of the encephalic lesion. Findings from 68 hematomas observed in the subacute or chronic phase suggest that their appearance is pathognomonic with visualization in SEpT1 of a crown of an intense signal at least equal to that of fat. The only difficulty at this period is the discovery of a hematoma within the fat: orbital, retroperitoneal... The collection of a subdural hematoma usually appears homogeneous, the intensity of the signal varying with red cell concentration and time. In the soft tissues, the intensity of signal is a function of concentration of hemoglobin and its derivatives and of volume of serous effusion. Images of 24 hematomas during the sequelae phase confirmed the appearance of a "biochemical shell" without signal in SEpT2 and allowed detection of the hematic contents of an occupying process even after long periods, sometimes after one year.

Preliminary findings on NMR imaging of 30 soft tissue tumors demonstrated the indispensable value of this examination (particularly when a surface antenna is used) for preoperative investigation and diagnosis of tumoral recurrence when compared with other radiologic techniques. The possible potential of NMR imaging for characterization of tissues, apart from lipoma or liposarcoma, cannot be evaluated at the present time.

A N.O.P. oriented C.T. in vivo of the head of the Pan troglodytes L. The N.O.P. was recognised from many works (E.A.C.). It permitted a biometric approach and very precise morphologic study of the brain and face in comparative anatomy.