L’angio-scanner cérébral multibarrette peut-il supplanter l’angiographie conventionnelle dans le diagnostic étiologique des hémorragies sous-arachnoïdiennes ?

AIM OF THE STUDY

To evaluate the reliability of CT angiography in the diagnosis of non traumatic subarachnoid hemorrhage.

MATERIALS AND METHODS

We prospectively studied 57 patients presenting with non traumatic subarachnoid hemorrhage. In all cases, CT angiography of the circle of Willis was performed, followed by conventional angiography. We compared the results of both techniques, with conventional angiography considered as the gold standard.

RESULTS

The specificity of CT angiography for diagnosing intracranial aneurysms was 100% with sensitivity and negative predictive values of 86% and 65% respectively. The aneurysms that were not diagnosed on CT angiography were located on the supra-cavernous internal carotid artery and their size was less than 5mm. Futhermore CT angiography failed to diagnose the other causes of subarachnoid hemorrhage.

CONCLUSION

CT angiography can be considered as a first line imaging technique for diagnosis of non traumatic subarachnoid hemorrhage. However, conventional angiography including three dimensional acquisitions must be performed for all cases where the cause of hemorrhage remains undiagnosed at CT angiography.

In vitro evaluation of 2D-digital subtraction angiography versus 3D-time-of-flight in assessment of intracranial cerebral aneurysm filling after endovascular therapy

BACKGROUND AND PURPOSE

The aim of this study was to evaluate 2D-digital subtraction angiographic (DSA) and 3D-time-of-flight (TOF) MR imaging in assessment of aneurysmal residue by using a pulsating silicon aneurysm model. For each imaging system, we studied intra- and interobserver reproducibility and the agreement between interpretations and reference measurements. We also examined how each imaging technique affected the operator's therapeutic decision.

METHODS

Two silicon aneurysm models depicting subarachnoidal aneurysms were used, one with a wide neck and one with a narrow neck. Each aneurysm model was placed in series on a pulsed flow circuit and was filled with Guglielmi detachable coils to simulate a clinical case. Each aneurysm was then gradually filled with silicon gel in increments of 10%, up to 100% to simulate different levels of occlusion (residual neck or dog ear, partial, complete) at each filling level. For each level of filling, we performed conventional 2D-DSA and 3D-TOF MR imaging. We submitted the images for examination by 2 senior medical staff with 2 readings per image. A combined reading of the 2 images was submitted to each expert to determine whether the 2 examinations were complementary.

RESULTS

The 2D-DSA analysis showed good reproducibility (k = 0.8 and k = 0.57) and agreement (k = 0.71) in describing "complete" treatments. The distinction between a "residual neck" and "partial treatment," however, was not reliable. The 2D-DSA provided a good description of the coil and silicon protrusion into the parent artery. The 3D-TOF analysis of the residual aneurysm, however, was not reproducible, though it was more effective than the 2D-DSA in evaluation of partially wide-necked aneurysms (k = 0.68 MR imaging vs k = 0.041 2D-DSA; P = .018). At the same filling level, the 2D-DSA analysis indicated repeat treatment more often than 3D-TOF analysis (P = .059).

CONCLUSION

The 2D-DSA remains the gold standard, but MR imaging is more effective in evaluating a "partial treatment." The 2D-DSA analysis indicated repeat treatment more often than the 3D-TOF for the same occlusion level. The distinction between "partial treatment" and a "residual neck" was not reliable with either method of evaluation.

Fetal brain injury

Improvements in MRI techniques widen the indications for fetal brain imaging and fetal brain injury represents the third indication of fetal brain magnetic resonance imaging (MRI) after the evaluation of suspected central nervous system (CNS) malformations and ventricular dilatation. Optimal MR imaging technique is necessary in order to collect as much data as possible about the fetal brain. Diffusion images can be used routinely in addition to the standard protocol of fetal brain MRI that consists of T1 and T2 weighted images of the fetal brain. Monovoxel proton magnetic resonance spectroscopy can also be performed in utero, but this technique is still more part of research protocol than of routine clinical protocol. Fetal brain injury includes hypoxia-ischemia, congenital infections (especially toxoplasmosis and cytomegalovirus infections), brain damage due to malformation such as vascular brain malformation and heart malformation, pregnancies at risk of fetal brain damage, and even inherited metabolic diseases, especially mitochondrial diseases. MRI findings in fetal brain injury consist of acute or chronic lesions that can be seen alone or in combination. Acute response of the fetal brain is less commonly seen than the chronic response compared to the brain response encountered in the postnatal period.

Normal galenic drainage of the deep cerebral venous system in two cases of vein of Galen aneurysmal malformation

INTRODUCTION

Vein of Galen aneurysmal malformations (VGAM) are assumed to be related to the persistence of the embryonic median prosencephalic vein of Markowski, which does not involute in cases of VGAM and becomes the venous collector of the shunt, characteristic of the malformation. The arterial feeders of VGAMs are all primitive meningeal arteries present during the embryonic period of the constitution of the malformation. It has also been assumed that the internal cerebral veins were absent in patients presenting with VGAM. There is no clear evidence indicating, however, that the deep venous structures cannot develop normally.

CASE REPORTS

We report on two cases of VGAM in which superselective retrograde transvenous catheterization and MRI demonstrated that normal internal cerebral veins were draining into the aneurysmal vein of Galen.

CONCLUSIONS

It is conceivable that, as in our patients, this drainage pattern is only angiographically detectable via selective retrograde transvenous drainage. The possibility of such normal deep galenic venous drainage must be considered in VGAM management, as it may imply occurrence of adverse effects when the malformation is occluded on the venous side.

MR imaging of fetal brain malformations

METHODS

From the generally accepted data on the morphogenesis of the brain, the principles for the classification of brain malformations are given, and the salient features of each malformation which may be considered as independent from the developmental stage and therefore practical for MR imaging in the fetus after mid-gestation, are discussed.

RESULTS AND DISCUSSION

However, the correlation with the clinical results in 150 cases of malformations out of a series of more than 1,000 cases of MR fetal brain imaging, demonstrates that beside the main, well-defined malformative entities, a significant degree of uncertainty remains. As the indication of further imaging is mainly based on the ultrasonographic findings, cases that are not identified as abnormal by US are not submitted to MRI (partial commissural agenesis and malformations of cortical development). A striking discrepancy exists between the findings of US and those of MRI, in the specific instance of the disorders of the posterior fossa (cystic malformations versus mega cisterna magna versus cerebellar defects), which may be only partly corrected by the use of strict anatomic criteria. Similar difficulties are observed for the diagnosis of nondestructive microcephaly.

CONCLUSION

Long-term prospective longitudinal clinical-radiological studies of these groups of patients are needed.

Histological and MR correlations in Gliomatosis cerebri

The diagnosis of Gliomatosis cerebri (GC) is known to be difficult and is still a matter of debate. In order to better define this entity, we studied clinical, neuroradiological, pathological and follow-up data of 9 patients affected with GC. MRI were done with T1 before and after gadolinium injection, and with T2-weighted images and Flair in 3 cases. Histological confirmation of glial proliferation was obtained in all patients by craniotomy or stereotactic biopsies. Patients were treated and followed-up in our center. The histological analyses highlighted a heterogeneous glial proliferation with various degrees of anaplasia in all the cases including 2 cases of oligodendroglioma, 1 case of anaplastic oligodendroglioma, 2 cases of anaplastic mixed oligoastrocytoma, 1 case of anaplastic astrocytoma, 2 cases of glioblastoma and 1 case of astrocytic proliferation typical of GC. The topography of the tumoral infiltration was characteristic involving mainly the white matter, basal ganglia and thalamus, brainstem and less often hypothalamus. More than two cerebral lobes were involved. Contrast enhancement, mass effect and necrosis were minimal compared to the extent of tumoral infiltration. Patients were treated with various schemes of treatment all including nitrosourea. Survival from diagnosis was under one year except for 2 patients (17 and 14 months). This study shows that the diagnosis of GC needs to be based not on pathological data alone, but on pathological, clinical and, above all, on radiological criteria. Response to therapy could not clearly be observed in GC, despite oligodendroglial component in 6/9 cases. Prognosis of GC was constantly poor.

[Value of single photon emission computed tomography in the characterization of fronto-temporal dementia subtypes]

DFT (fronto-temporal dementia) was diagnosed in 33 patients (17 males and 16 females), mean age 74.9 years, using the criteria from Neary et al. (1998). The severity of the disease was evaluated based on the presence or absence of 4 clinical groups of signs (behavioral, affective, neurological signs and language) allowing the calculation of a global clinical ratio on 20. A CT-scan and a Single Photon Emission Computed Tomography (SPECT) scan using Tc99m-ECD with quantification of brain perfusion were then performed. This study confirmed the classical clinical forms of DFT: a psycho-affective form (21%), where negative symptoms are predominant, and a behavioral disinhibited form (9%). Most of our cases (40%) corresponded to a global form. Finally we also identified a fourth clinical form: cognitive form because of predominance of language disturbances (30%). Concerning SPECT, we found 4 topographic forms: frontal global (46%), frontal superior (24%), frontal inferior (15%) and frontal unilateral (12%). In the frontal inferior form, behavioral disturbances were correlated to the intensity of frontal inferior hypoperfusion, corresponding to an orbito-frontal dysfunction. In the frontal superior form, psycho-affective disturbances (apathy) were correlated with frontal superior hypoperfusion (anterior cingulum and superior dorso-lateral cortex). Finally, in global and frontal inferior SPECT forms, language disturbances were correlated with a frontal inferior hypoperfusion (prefrontal and inferior left frontal cortex).

[Craniopharyngioma in children: MRI study of 43 cases]

BACKGROUND AND PURPOSE

Craniopharyngiomas are intra-cranial tumors, relatively frequent in children, expanding in the pituitary stalk axis, from the third ventricle to the sphenoid body. Plain films and CT scan generally show a calcified lesion, deforming the sella turcica. MRI improves tumor description and topographic and structural analysis of the lesion. The aim of this study is to analyze the MRI aspect of craniopharyngiomas in a pediatric population and to correlate findings with surgical data.

METHODS

MR and CT studies of 43 pediatric cases of histology-proven craniopharyngiomas were reviewed retrospectively. Tumor emergence, extensions and signal on different sequences were recorded. We searched for radio-surgical correlations.

RESULTS

Craniopharyngiomas can be classified into two groups: intra-sellar tumors and third ventricle floor tumors (infundibulum and tuber cinereum). Preferential routes of extension are observed in each group correlated with consistency (cystic and/or solid). Surgical data confirmed these results.

CONCLUSIONS

MRI is crucial for the pre-therapeutic evaluation of craniopharyngiomas allowing not only a detailed description of the tumor but also guiding therapeutic decisions. This series demonstrated that craniopharyngiomas exhibit two different types of localization and behavior. Embryonic development of the tumor explains the topographical differences.

Neurocutaneous melanosis: radiological-pathological correlation

We report the case of a young patient with neurocutaneous melanosis (NCM) who presented with temporary aphasia and right hemiparesis followed by progressive coma and death. To our knowledge, this is the first case of this disease examined by CT, MRI, angiography and in which an autopsy was performed to assert the diagnosis with histology. Besides, we discuss differential diagnoses and interest of MRI for early diagnosis.

[MRI: an essential examen for the management of sacrococcygeal chondromas]

Chordomas are rare tumors, involving mainly the sacrococcygeal area and the clivus. Although a significant radiological semiology exists (osteolytic, lobulated, calcified tumor), the definite diagnosis is histological. Five cases of sacral and/or coccygeal chordomas were studied by CT scan and MRI. Clinical, radiological (tumoral topography and extension) and histological data were noted in all cases. At CT scan, the tumor was median, osteolytic, often calcified, of intermediate density, sparing iliac bones. MRI showed, in all the cases, a tumoral lobulation making easier the diagnosis of chordoma. Futhermore, as compared to CT scan MRI brought new information for the study of the tumoral extension, revealing a frequent involvement of adjacent muscles and spinal canal. It also showed that the tumor most often spared the rectal wall. These data are fundamental in the management of patients: the therapeutical aim must be, if possible, a complete removal of the tumor. Thus, besides its interest in the diagnosis, MRI appears to be essential in the pre-therapeutical assessment of sacro-coccygeal chordomas.

MRI of the intracranial corticospinal tracts in amyotrophic and primary lateral sclerosis

Our aim was to investigate the corticospinal tracts (CST) in motor neurone disease, using MRI, and to correlate findings with clinical data. We studied 31 patients with amyotrophic (ALS) and eight with primary lateral sclerosis (PLS). The signal from the CST was classified into four grades on T2-weighted images, and compared to T2-weighted images of 37 age-matched control subjects. No abnormalities were seen in the CST on T1-weighted images and were rarely evident on proton-density weighting. Variable high signal in the CST was found on T2-weighted images in 35 patients, and in 29 control subjects. Our grades 0 and 1 were more frequent in control subjects, grades 2 and 3 more frequent in patients. We found no correlation between the high signal and clinical data, including the duration of the illness. We therefore conclude that this technique is neither sensitive nor specific except in grade 3 which is quite specific for ALS. In half the patients we found atrophy of the superior parietal gyrus, which merits further study.