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Torticollis in children must always instigate a search for trauma. Many other etiologies can be found. The authors report a case of postmedicinal atlantoaxial rotatory pseudoluxation (AARP) occurring in a child. This child had fallen down in the morning with head trauma followed by headache. Clinically, a stiff neck with an irreducible right rotation of his neck, and an osteotendinous hyperreflexia were noted. There was a C1-C2 rotatory dislocation with no traumatic lesion on the cervical CT scan. After a few hours, the torticollis spontaneously reduced and then reappeared on the left side. This clinical fluctuation and the absorption of metoclopramide (Primperan) started in the morning for acute gastroenteritis provided the diagnosis of AARP. This entity was confirmed by the good clinical and radiological follow-up and was caused by the substantial ligament laxity of the craniovertebral junction encountered in children. The analysis of medical imaging and the systematic search for a medicinal cause helped make the right diagnosis.

We reviewed 11 cases of intramedullary cavernous haemangiomas (IMCH) studied by MRI, to assess its diagnostic value in these lesions. Follow-up MRI was obtained in five patients 7 days-2 years following the initial study. In one case a postoperative examination was obtained. The diagnosis was pathologically proven in ten cases, and supported in the last by a family and personal history of cavernous haemangiomas. A reticulate appearance with areas of mixed signal intensity in both T1- and T2-weighted images was the most common finding. Homogeneous high, low or intermediate signal intensity was each found in one case. Two small lesions gave low signal. A rim of low signal was less common than in cerebral cavernous haemangiomas. In one case, the brain showed more than 20 lesions with the MRI appearances of cavernous haemangiomas. In two of five patients, serial preoperative MRI showed progressive disappearance of high-signal areas on both T1- and T2-weighted images. To find a haemorrhagic intramedullary lesion on MRI is not rare. Although the appearances are not pathognomonic, an IMCH can be suggested. We suggest that the following characteristics may help: (1) a personal and/or family history of cavernous haemangiomas; (2) typical MRI appearances of mixed acute, subacute and chronic haemorrhage; (3) a tendency for signal intensity to decrease on follow-up; (4) normal spinal angiography; and (5) associated brain lesions.

We present three cases of suprasellar cavernous haemangioma with characteristic high-field MRI features. Clinical, CT and MRI data were retrospectively analysed. The patients had progressive neurological, endocrinological and visual complaints. In the three cases CT revealed a high-density suprasellar mass. In all cases the combination of a reticulated core of mized signal intensity with a surrounding rim of decreased signal on T1- and T2-weighted MRI scans suggested the presence of a cavernous haemangioma. Two patients underwent surgical biopsy after their first MRI examination. Cavernous haemangiomas located in the suprasellar area may show typical MRI features.

A total of 162 patients with suspected acoustic neuromas underwent MR imaging at 1.5 T. All patients were injected with Gd DTPA or DOTA. In 72 patients, uni- or bilateral acoustic neuromas were detected. 18 cases were equivocal: In 9 cases, contrast enhancement was due to other tumors (5 meningiomas, 2 metastases, 1 hemangioma). In 1 case, misinterpretation resulted from partial volume effects with the petrous bone marrow. In one patient, previously operated on, increased signal was due to postoperative fat graft. Four hypersignals were due to intracanalicular venous or meningeal enhancement. Three cases are still equivocal. Most of the diagnostic problems may be obviated by precontrast MR imaging, multidimensional 3-mm sections, and fast imaging.

Torticollis in children must always instigate a search for trauma. Many other etiologies can be found. The authors report a case of postmedicinal atlantoaxial rotatory pseudoluxation (AARP) occurring in a child. This child had fallen down in the morning with head trauma followed by headache. Clinically, a stiff neck with an irreducible right rotation of his neck, and an osteotendinous hyperreflexia were noted. There was a C1-C2 rotatory dislocation with no traumatic lesion on the cervical CT scan. After a few hours, the torticollis spontaneously reduced and then reappeared on the left side. This clinical fluctuation and the absorption of metoclopramide (Primpéran) started in the morning for acute gastroenteritis provided the diagnosis of AARP. This entity was confirmed by the good clinical and radiological follow-up and was caused by the substantial ligament laxity of the craniovertebral junction encountered in children. The analysis of medical imaging and the systematic search for a medicinal cause helped make the right diagnosis.

Rathke's cleft cysts are non neoplastic lesions of the sellar area that seldom are symptomatic. Their incidence has been underestimated before magnetic resonance imaging (MRI). The aim of this work was to assess the value of MRI in the diagnosis and differential diagnosis of Rathke's cleft cyst based on a retrospective review of 12 cases and a review of the literature.We retrospectively reviewed the MRI features of 12 patients with Rathke's cleft cyst collected over 4.5 years. Patients included ten females and two males (mean age: 39 years). The most common presentation was the association of dysmenorrhea and pituitary dysfunction. MRI examinations were performed using a 1.5 Tesla system, T1 and T2 weighted sequences performed before and after Gd- DTPA injection. Signal intensity, shape, size and location of the lesion were analyzed.In all cases, MRI examination showed a cystic lesion of variable size and signal intensity. The cyst was purely intrasellar in nine cases and a suprasellar extension was noted in three cases. Five patients underwent surgery providing pathological confirmation, four underwent routine follow-up and three were lost of follow-up.We conclude that MRI is an efficient tool for diagnosis, allowing appropriate medical decision making.

We prospectively evaluated 30 patients with CNS cavernous angioma with a high field (1.5T) magnetic resonance imager. In all patients the MRI protocol included: gradient echo T1*-weighted imaging, spin echo T2*-weighted imaging and gradient echo T2*-weighted imaging. We evaluated each case for the number of lesions detected on each sequence. Gradient echo T2*-weighted imaging with a long TE (TE: 35ms) was the most sensitive sequence for the detection of cavernous angiomas allowing detection of small lesions that were not identified on the other sequences.

MRI is becoming an important tool of examination of the head and neck. However, certain dental alloys cause artifacts characterized by a loss of signal surrounded by bright line and sometimes distortions. In our work, we studied artifacts caused by Titanium, metallic biomaterial used for oral implantology. Therefore, 2 experimental were investigated in a 1.5 T MR unit, with 2 sequences commonly used (SE, GRE). The investigation showed minor artefacts, without distortions. In order to minimize these "ghost images", the Titanium and its alloys should be an alternative.

Hemangiomas are tumors. Hemangiomas near the geniculate ganglion or in the internal acoustic meatus are well known but rare. We present two cases of hemangiomas located at the porus acusticus, an even more rare site. MRI showed a millimeter-sized tumor, located in the porus acusticus, developing perpendicular to the axis of the acoustico-facial nerves, surrounding them. They were hyperintense on T1-weighted images, strongly hyperintense on T2-weighted images with a characteristic progressive and marked enhancement after injection of gadolinium DTPA. Similar signal abnormalities were present in the adjacent temporal bone, and CT scan demonstrated a honeycomb appearance with intratumoral bony spicules. These imaging criteria allows differentiation between hemangioma and neurinoma. We hypothesize that this location is related to the presence of a rich vascular plexus of the dura mater in this area.

The central canal of the spinal cord is present at birth and becomes progressively obliterated. Cadaver studies have shown that it may persiste partially or completely. To our knowledge, this entity has not been described on MRI. We reviewed 794 MRI studies of the spinal cord, and found 12 patients (aged 14 to 65 years) who had an intramedullary cavity. The cavity was at the junction of the ventral 1/3 and dorsal 2/3 of the spinal cord, except at the level of the lumbar enlargement, where it was central. It was filiform in most cases, although sometimes fusiform (3 to 4 mm in diameter), and had regular contours. The cavity were thoracic in 69 % of cases. The clinical features were totally unrelated to the image, and there were no anatomical factors (Chiari malformation, dysraphism) predisposing to syringomyelia. The images were perfectly compatible with a persistent central canal, which we interpret as a variant of normal anatomy. Therefore it is important to regard these findings as normal, to avoid unnecessary treatment and follow-up.

The neurocysticercosis is an infestation of the central nervous system by larvae of Taenia solium. The disease is endemic in a few countries of Latin America, Asia, and Africa and is becoming increasingly prevalent in the United States and Europe. The immigration of individuals from endemic areas and the tourism in these areas require a good knowledge of this disease. A retrospective study evaluating the neurocysticercosis lesions with MR and CT is proposed. Parenchymal, subarachnoid and intraventricular cysts are evaluated. We were able to recognise four CT and MR stages. MR was useful in detecting the cysts of neurocycticercosis in the first stage but was inferior in the detection of parenchymal calcifications.

MRI is the best imaging method to evaluate syringomyelia. It is important to study from the posterior cranial fossa to the sacro-lumbar region and also the supra-tentorial structures. This complete analysis is essential to classify the syringomyelia and to investigate other associated malformations. Radiographs and CT scan are useful to analyze bone structures. For MRI, the new sequences with phased-array coils are also very important to study the entire spinal cord and the posterior fossa. It is essential to study the spinal cord with sagittal and axial spin echo T1 and fast spin echo T2 weighted images with sometimes coronal view, particularly when the patient presents a scoliosis, to have a correct morphological and functional evaluation. MRI gives an excellent study of the spinal cord with an excellent analysis of a primitive or foraminal syringomyelia, but also traumatic, infectious or post arachnoiditis syringomyelia. Spin echo T1 weighted images with injection of gadolinium can be used if an intra-medullary tumor is suspected. MRI is also useful for the post-operative follow up to evaluate the persistence of the medullary cyst and the enlargement of the foramen magnum.

Results of CT and MRI explorations in 8 patients with cerebrospinal fluid (CSF) fistulae are reported and compared with surgical findings in 7. Sensitivity of MRI (CISS and fast T2 spin-echo sequences) was excellent giving perfect correlations with surgical findings in 7/7 cases. CT and MRI were found to provide complementary information suggesting they should be used in combination as first intention explorations of suspected CSF fistulae. Computerized cisternography should be used if MRI is contraindicated or if a clinically and biologically proven CSF fistulae is not visualized by CT or MRI.

A case of cystic schwannoma that presented as an intraaxial lesion on CT is reported. Magnetic resonance was able to detect the extraaxial origin of the tumor.

The authors report an exceptional case report of tumor like evolution of a completely thrombosed aneurysm of the right vertebral artery suggestive of neurinoma of the XII nerve. We describe CT, MRI, MR-angiography. The diagnosis has been established by pathologic study after surgical extraction. Our case demonstrate the possibility of growth of totally thrombosed aneurysms and we discuss various mechanisms.

An 8-year-old child was examined because of conductive hearing loss with a retrotympanic mass on otoscopy. CT and MR angiography showed a large inferior tympanic artery traversing the hypotympanum and joining a thin, irregular internal carotid artery with a normal middle meningeal artery. These investigations, coupled with knowledge of the embryological development allowed a diagnosis of a complex vascular anomaly in the middle ear and avoided potential surgical complications.

Magnetic resonance imaging (MRI) gives an accurate analysis of Meckel's cave variability. Images were acquired in 50 patients with several sections for anatomical comparison. Using several sections, MRI is a suitable method for better analysis of the trigeminal cistern. The most frequent findings are symmetrical trigeminal cisterns. Expansion of Meckel's cave or its disappearance has pathological significance.

Fifty files were evaluated to determine the normal anatomy of the cranial nerves. All the cranial nerves were studied including the labyrinth, in different planes with a 3DFT-CISS imaging technique. The 3DFT-CISS is especially interesting to study cranial nerves because of the excellent contrast with CSF-fluid and the possibility of thin sections. It might be essential for the diagnosis of neuralgia and cranial nerves paralysis.

We report a firearm wound of the brain which could not be analyzed by computed tomography because of induced artifacts. MRI study was remarkably after verifying the non-ferromagnetic nature of the projectiles.

A magnetic resonance imaging (MRI) study of the normal pineal gland and pineal simple cysts was performed in 762 cases. A fine section technique (maximum 3 millimeters) enabled most of the times the identifying of a normal pineal in addition to demonstrating that a pineal without any cyst shows an isointense signal in T1 and T2 which, in turn, is enhanced following gadolinium. The measure of the normal pineal was of about 6.1 millimeters in its diameter length. Pineal simple cysts were observed in a 2.6% frequency in relation to the whole series (762 cases); however reaches 6.1% when only the visualized pineals were considered (329 cases). Also, it was found out that simple cysts were not correlated to age or gender. Simple cysts characteristics are: dimension less or equal to 20 millimeters; absence of expansive effect; similar signal to that of the cerebrospinal fluid; absence of cyst growth.

We present a retrospective study in order to analyze the abnormalities noted on MRI in 27 cases of myelopathy excluding tumors, explored between 1994 and 1996. The different lesions were: Multiple Sclerosis (n = 11), Spondylotic myelopathy (n = 3), Neurosarcoidosis (n = 4), CMV Myelitis (n = 1), Radiation Myelopathy (n = 1), Spinal Dural Arteriovenous Fistula (n = 1), Intramedullary Cysticercosis (n = 1), Infarct (n = 5). The exams have been made on 1.5 Tesla Magnetom Vision Siemens or GE Signa machine. All patients have had axial and sagittal views with coronal complementary study in 4 cases. Sequences were Spin echo pT1 (TR: 560, TE: 12), Fast Spin echo pT2 (TR: 3 500, TE: 99 or 128), and gradient echo pT2 (TR: 700, TE: 22, Angle: 25 degrees). Intravenous injection of Gadolinium has been made in 16 cases (0.1 mmol/kg). We have studied the presence or not of a signal abnormality in pT1 and/or in pT2, of enhancement, and its topography (cervical, thoracic, lumbar). We classified lesions in central and/or peripheral and according, to their topography in anterior, posterior or lateral type. The form has been classified in four types (nodular, triangular, "pen like", plage). Extension in transversal (superior or inferior to half medullary surface) and cranio-caudal directions (inferior to one vertebrae, between one and two vertebrae, superior to two vertebrae) has been also classified. Others intra or perimedullar and encephalic abnormalities have been noted. We analyzed the results for each pathology and underline the essential diagnosis criteria noted (low cranio-caudal and transversal extension with frequent triangular form of Multiple Sclerosis lesions, frequent suggestive abnormalities of the encephale (82%) in Multiple Sclerosis, intra and perimedullar enhancement with deformations of the surface of the spinal cord in Sarcoidosis' lesions, extended dorsolumbar "pen like" lesions with inconstant enhancement of infarcts, focal plage lesions centered on degenerative changes of the spinal canal in spondylotic myelopathy, bony lipomatous involution in front of intramedullary radiation plage lesion...) and also review the literature and confront their results to it. We insist on the difficulties in classifying myelopathy (radio-clinical terminology discordances, identical signal abnormalities frequently caused by different illness, necessity to compare to pathologic results). We propose a MRI study protocol that should interest the whole spinal cord and comport T1 weighted without and after gadolinium sequences, T2 weighted sequences (with always a gradient echo type). 2 or better 3 different plans should be made. A complementary study of the brain by MRI is often useful. Clinical study, biology, evolution, MRI and when possible pathology all are necessary to better understand myelopathy's mechanisms.

We present a case of osteoid osteoma of the petrous bone presenting with progressive sensorineural hearing loss. CT showed a dense homogeneous mass at the promontory surrounded by a thin bony border. On MRI this lesion gave intermediate signal intensity on T1- and T2-weighted spin-echo images and enhanced intensely with gadolinium. Surgical removal and pathological study proved the diagnosis.

Spontaneous regression of disc herniation is well known but the mechanism is not clear. Some hypotheses have been made. We present here a large thoracic disc herniation diagnosed by MRI which completely regressed one year after a medical treatment with complete amendment of symptoms.

The case of an osteoid osteoma of the middle ear in a 42 year old man is reported. No former case has now been reported in the literature for this localization. The suspected diagnosis of osteoid osteoma was based on the pain and the findings of bone computerize tomography. In our case, the osteoid osteoma was totally painless and the diagnosis was made after surgical findings by histological studies. Some clinical and imaging points, pathologic findings and differential diagnosis are also discussed.

Kallmann syndrome is a disease clinically characterized by the association of hypogonadotrophic hypogonadism and anosmia or hyposmia. Most cases have been recorded among men. It is a genetic disorder with a specific gene location on the X chromosome. The cells that normally express luteinizing hormone-releasing hormone or LHRH fail to migrate the olfactory placode to the forebrain. The lateral projections of the olfactory placode also fail to induce development of the olfactory bulbs and tracts.The aim of this study was to compare the MRI appearance of the olfactory sulci, the olfactory bulbs and frontal lobe between groups. The first reference group was composed of 20 subjects and the second group of 18 patients suffering from Kallmann syndrome. For all studies we used a 1.5 T magnet system (Signa GE). We performed two sagittal and coronal T1-weighted sequences in spin echo (TR = 600 ms, TE = 12 ms) with interleaved 3 mm slices and a 14 cm field of view.In the first group, the two olfactory bulbs were always seen on coronal slices just behind the crista galli measuring 2 to 3.2 mm transversally. On sagittal slices, in 60% of the cases two bulbs were seen (3 mm laterally of the pituitary stalk) and in the other 40% only one bulb was seen. The length of the bulb has been measured between 6 and 11 mm. We noticed a plat frontal lobe in 85% of the cases. In the second group the olfactory bulbs were never visible among the 18 patients suffering from Kallmann syndrome. The hypoplasic sulci were hardly visible and their size was less or equal to 1 cm and the frontal lobe was triangular in 80% of the cases. One patient had hypoplasia of corpus callosum.MRI is helpful tool to demonstrate abnormalities of the olfactory system which are always present among patients suffering from Kallmann syndrome. MRI can also show, at the same time, a possible associated brain abnormality.

In this retrospective study the respective values of MRI and CT in the location and nature diagnoses of facial nerve haemangiomas were evaluated. The four male patients examined were 31, 44, 56 and 62 years old; they presented with facial nerve pals and/or cochlear-vestibular dysfunction. The haemangiomas were located in the internal auditory canal, the geniculate ganglion, the tympanic segment of the facial nerve and the petrous bone apex. MRI revealed a tumoral process, while CT showed intratumoral calcifications and provided a diagnosis of mass nature in two cases. In the other cases the pre-operative diagnosis was neurinoma of the VIIIth or VIIth cranial nerve. Histology ascertained the diagnosis. MRI is the method of choice in cases of facial paralysis or cochlear-vestibular dysfunction if a tumoral cause is suspected. Haemangioma is an uncommon tumour without specific image, except for calcifications and neighbouring osseous reactions. It must also be considered on the basis of clinical and topographical findings revealed by CT and MRI imaging.

From July 1993 to April 1994, forty dentascans were performed at Bicetre Hospital, on an Elscint Elite Plus scanner for: chronic sinusitis (18 cases); cystic pathologies (8 cases); pre-operative assessment for dental implantation (14 cases).Dentascan images permitted a precise analysis of dentomaxillary anomalies. In all cases they demonstrated the anatomical relationships of the lesions, permitting a determination of potential complications. In chronic sinusitis dental pathology was demonstrated including peri-apical granulomas or cysts breaks or elevations of the floor of the maxillary sinus, malplaced dental filling material in the maxillary antrum and fistula tracks. Among the 14 pre-operative assessments, four cases of infectious lesions were demonstrated, thereby counter-indicating dental implantation.The dentascan appears to be very useful for dentomaxillary pathology by facilitating diagnosis and the formulation of treatment and operative strategies.

MRI is the standard exploration of intramedullary tumours. Following up the patients is of prime importance to detect and treat possible recurrences at an early stage. The purpose of this paper is to specify the postoperative MRI semiology of intraspinal gliomas. During the 1986-1992 period, 47 patients operated upon in the Bicêtre hospital for primary intraspinal tumours were followed up with high-field MR (1.5 Tesla, Signa, G.E.). The retrospective visual study was carried out by two neuro-radiologists. The patients' group consisted of 24 women and 23 men aged from 15 to 67 years (mean 38 years). The tumours treated were 29 ependymomas and 18 astrocytomas. Eighty-five MRI examinations were analysed. Most of them comprised at least two planes in T1 and T2-weighted spin echo sequences with gadolinium injection, then only T1-weighted spin echo sequences after gadolinium injection (0.1 mmol/kg). The mean postoperative follow up period in the 47 patients was 32 months (range 7 to 84 months). Contrast enhancement of the spinal cord was observed in 20 cases. In the 6 patients with recurrence (5 astrocytomas, 1 malignant ependymoma) there was a segmental increase of spinal cord volume with contrast enhancement after gadolinium injection. In 3 out of these 6 patients clinical deterioration appeared later than MRI semiology. In clinically stable patients neither enhancement nor increase in spinal cord size was found in 27 cases, and enhancement alone was noted in 12 cases. There was no reliable criterion in the analysis of post gadolinium signal enhancement that could be used to differentiate recurrence from cicatricial contrast enhancement.(ABSTRACT TRUNCATED AT 250 WORDS)

Cysts of the posterior fossa are common in the literature, but the simple cyst is rarely considered in the differential diagnosis of these cysts.The cases of two female patients with clinical symptoms of expansive cerebellar lesion are described. These patients were explored by MRI. They were operated upon and an anatomico-pathological diagnosis was made.Both patients had an intraparenchymal cystic lesion of the cerebellum. No mural nodule and no enhancement after gadolinium injection were noted. The anatomico-pathological examination confirmed that the lesion was an intra-parenchymal simple cyst the walls of which showed no tumoral features.Although this anatomico-pathological entity has not previously been described in the literature, such rare diagnosis should be borne in mind in patients presenting with a cystic tumour of the posterior fossa. MRI is of paramount importance in the evaluation of these lesions, but the anatomico-pathological diagnosis is indispensable to exclude a possible tumour.

MRI has now been recognized as the best technique for exploration of spinal tumours and, in particular, tumours within the spinal cord. Based on a retrospective study of 74 operated glial tumours, we are trying to define a specific semiology for intramedullary astrocytomas and ependymomas. Thirty-four cases were selected including 17 astrocytomas (7 low-grade, 10 high-grade) and 17 ependymomas (1 of which was grade III) for whom the pre-operative MRI examination was complete, with T1-weighted sequences without, then with gadolinium, and T2-weighted sequences. The examination was performed using a high-field and in most cases 1.5 Tesla machine. Analysis, correlated with operative data and pathology results, comprised on the one hand patients' distribution by age, sex and location of the tumour on the spinal cord, and on the other hand the MRI semiology concerning the sagittal and axial localization of the fleshy portion after gadolinium injection, the limits of the tumour, the homo- or heterogeneous character of its enhancement, the possible existence of stigmas of intra- or peritumoral chronic bleeding, and finally the presence or absence of associated cysts in the 34 exploitable cases. Some semiological differences were elicited between astrocytomas and ependymomas: the patient's age at the time of diagnosis was predominantly 0 to 20 for astrocytomas (astrocytomas 39%, ependymomas 4%), and the well-limited character of the fleshy portion of the tumour after gadolinium injection was found in 70% of ependymomas, 40% of high-grade astrocytomas and 14% of low-grade astrocytomas. The homogeneity of contrast enhancement in ependymomas has been classically defined, but it did not show in our series. Finally, it seems that high-grade astrocytomas are characterized by the rare presence of hemosiderin deposits (high-grade 20%, low-grade 57%, ependymomas 58%) and by the absence or reduced extension of overlying and underlying cysts.

Erdheim-Chester disease is related to a tissue infiltration of foamy histiocytes. Results of immunoperoxydase stains for S-100 and T6 protein, the Langerhans cells antigen, is negative. It is a multisystemic disease, and it particularly involves bones and orbit. The visual prognosis is threatened, and the disease may lead to a fatal issue. Treatments have poor effects on the disease. Patients sometimes have good symptomatic response to corticotherapy. This case was revealed by headaches and diabetes insipidus. The orbital infiltration was asymptomatic.

High resolution computed tomography (CT) is today the best imaging to study chronic middle ear diseases. In a retrospective analysis of 85 chronic otitis media (cholesteatoma or not), the authors emphazise the diagnostic value of CT scan, its preoperative's role and the radiologic imaging of cholesteatoma. In our study, the radiosurgical correlation rate is 0.6 regarding positive diagnosis in chronic otitis or cholesteatoma. The malleus and incus analysis is correct, but stapes is not observed in 40% of cholesteatoma. The correlation of surgical and radiographic findings is excellent regarding the scutum, the horizontal semicircular canal (0.7), the tegmen (= 0.6), bad for the canal of facial nerve (0.5). The actual extent of chronic otitis media lesions is overestimated by CT scan in 70% of cases. The correlation's rate is reliable for epitympanum and aditus. To conclude, the preoperative CT is necessary in those cases: closed eardrum cholesteatoma, single functional ear, clinical complications and doubtful diagnosis.

Proptosis, decreased vision and oculo-motor palsies developed in the left eye of a 14-year-old girl, without neurofibromatosis signs. Computed tomographic (CT) Scans of the head and orbit showed a large fusiform expansion of the left optic nerve without intracranial involvement. Magnetic resonance imaging improved contrast resolution over CT Scanning. A neurosurgical approach was performed and the optic nerve was resected from the back of the globe to the intracranial portion. Microscopic sections demonstrated oligodendroglioma, an unusual form of optic nerve glioma.

Numerous techniques have been used for imaging salivary glands including standard radiography, scintigraphy, sialography, echography, computed tomography and finally NMI. These different techniques each have their own indications or complementary role. We therefore developed a protocol for using the different imaging techniques according to the different salivary pathologies encountered. This protocol is given as an examination flow chart to be used in light of clinical findings. A large number of images selected by P. Laudenbach illustrate the typical pathologies encountered. Special emphasis is placed on sialography, an important imaging technique, unfortunately somewhat neglected.

Magnetic resonance (MR) findings in 16 patients operated on 21 spinal cord hemangioblastomas were reviewed. Three of these patients had von Hippel-Lindau syndrome. 13 patients had Gadolinium-DTPA enhanced MR and 2 had dynamic sequences. Using Gd-DTPA makes the diagnosis of hemangioblastomas considerably easier compared to conventional non contrast MR. Findings are specific: a tumor nodule with, as a general rule, an extensive cyst formation; the nodule shows intense, earliness, homogeneous contrast enhancement as the cyst wall does not. In less typical cases, dynamic sequences may be useful in order to distinguish hemangioblastoma from other spinal cord tumor nodules. Today, MRI is the diagnostic modality of choice and angiography should not be used. MRI is also an excellent way to check the central nervous system and the visceral manifestations in a case of von Hippel-Lindau disease and to follow up the patients.

MRI has transformed the diagnosis of cavernous hemangioma, a hamartoma that is most often located in the central nervous system. The appearance of this lesion is fairly characteristic with MRI. This technique has allowed distinguishing multiple forms. Encephalic sites are most frequent, with rare medullary sites, and double brain and cord locations are exceptional. Many cases of single or multiple brain involvement have now been reported. Series of medullary involvement are much less frequent and include few cases. Double sites in the brain and cord are exceptional. The authors present a case of cavernous hemangiomas of the central nervous system with multiple encephalic sites associated with a single medullary site confirmed by surgery.

Routine volume measurement techniques most often produce a rough approximate with poor accuracy for smaller structures. The results are generally improved by increasing the examination time, so that the technique then becomes unusable in daily practice. We propose a semiautomated volume calculation method with MRI, and its application to the surveillance of non-operated acoustic neuromas. This calculation technique, based on a threshold-setting method, allows accurately delineating the contours of the structures to be measured on each section and quickly calculating the total volume. After testing its reliability on control volumes, this techniques has been used to assess the evolutive nature of 16 acoustic neuromas with mild symptoms in 15 patients rejected for surgery. The radiological examinations were 428 days apart in average. On the basis of the obtained results, a theoretic tumor doubling time was calculated, thus allowing comparison between all patients. All controlled neuromas had a theoretic doubling time ranging from 427 to 4,884 days, corresponding to little- or non-evolutive lesions, which may be explained by the series selection bias excluding evolutive tumors referred to surgery. Owing to its rapidity and easy use, this semiautomated volume calculation technique for MRI seems to be very interesting as it allows reliably quantifying a volume variation that is usually estimated approximately.

Neuromas and meningiomas represent by far the most frequent tumors of the cerebellopontine cistern (respectively over 80% and over 10%). Secondary malignant tumors are exceptional.Presentation of four cases of malignant tumors of the cerebellopontine cistern, either revealing or complicating a primary tumor: a bronchial cancer, a cancer of the kidney, a medulloblastoma and a lymphoma. Patients were studied in T2- and T1-weighted high-field MRI sequences before and after gadolinium injection.The four tumors were enhanced by gadolinium and shown to invade the internal auditory canal, including one bilateral involvement. In most cases, the tumors were slightly heterogeneous and had irregular margins.These observations suggest that other diagnoses than acoustic neuroma should be taken into account.

Study of the pituitary stalk pathology about six demonstrative cases. This illustrative cases are described after review of literature, anatomy and imaging modalities. CT and MRI are very sensitive technics but not very specific.

Spinal subdural hematomas are rare. They should be considered in the diagnosis of spinal cord compression. Prompt surgical treatment, if it is performed, may lead to complete recovery of the neurological deficit. But such treatment is not always necessary because of possible spontaneous recovery. MRI appears to be the method of choice to reveal hematomas even of small size and to follow up patients after treatment.

Owing to computer programs, computed tomography allows obtaining sections of the facial structures in all spatial planes and to "pile up" all sections to reconstruct the structural unit studied. In addition, these images can be reconstructed by selecting a density threshold, for example that of dentin or of enamel, isolating those from their bony environment, and thus the patient's dental arch can be visualized as if one was manipulating a pair of dental models. The first results obtained with this technique are presented, and they seem to be highly promising.

Lumbar subdural abscesses have rarely been reported in the literature, and the complications of epidural infiltrations predominantly include arachnoiditis, meningitis and epidural abscesses. We report a case of lumbar subdural abscess confirmed by surgery, which appeared following epidural infiltration for lumbar sciatica and was examined with computed tomography and MRI. Only the latter technique alone showed the abscess, after gadolinium injection, and established its intradural site.