Contrast-enhanced three-dimensional fast imaging with steady-state precession (FISP) MR angiography of supraaortic vessels: preliminary results

BACKGROUND AND PURPOSE

The purpose of this study was to assess the effectiveness of contrast-enhanced fast three-dimensional (3D) MR angiography in depicting both the carotid and vertebral arteries in their cervical portions and to compare MR angiography with conventional angiography for the evaluation of arteriosclerotic disease.

METHODS

Twenty-seven patients with ischemic cerebral events in the anterior (n = 18) and posterior (n = 9) circulation underwent contrast-enhanced 3D MR angiography in the coronal plane. MR angiograms were examined in a blinded fashion by two observers independently. Stenosis was classified according to the appearance of the residual lumen (no stenosis, mild stenosis, moderate stenosis, severe stenosis, occlusion). Conventional angiography was used as the standard of reference.

RESULTS

Proximal great vessels and carotid siphons were not assessable on MR angiograms in 35% of cases owing to limited coverage. All cervical and petrous segments of the internal carotid arteries (ICAs) and 93% of the extracranial vertebral arteries were assessable. Flow-related artifacts were observed in seven cases of severe stenosis, including three with signal void at the site of narrowing and four with signal loss in the distal ICA. Interobserver agreement was good and significant. Overall agreement between 3D MR angiography and conventional angiography was good for the anterior and posterior circulations despite a tendency toward overestimation of stenoses on MR angiograms. Clinically relevant stenoses and occlusions were correctly identified on 3D MR angiograms, providing good sensitivity and specificity.

CONCLUSION

Contrast-enhanced 3D MR angiography is a promising tool for assessing arteriosclerotic lesions of supraaortic vessels. Further studies with larger groups are required to determine its value for patient care.

[Contribution of fast-sequence three-dimensional MRI angiography with Gadolinium injection in the evaluation of supra-aortic vessels]

Sixty-nine patients with cervical atherosclerotic disease were evaluated by Magnetic Resonance (MR) angiography using a coronal 3D gradient echo gadolinium enhanced sequence. The image quality was evaluated for each artery and ostium on MIP reconstructions. A comparison with conventional angiography was achieved in 27 patients. All MR examinations were assessable; a second injection was performed in ten patients. All carotid bifurcations were visualized. The ostium of the common carotid artery was not assessable in 44% of cases due to the limited coverage. The evaluation of the posterior circulation was good in 90% of cases. The agreement between MR angiography and conventional angiography was good despite a tendency to overestimate moderate stenoses. Stenoses greater than 70%, carotid occlusions and vertebral stenoses greater than 50% were correctly detected.

[Residual deficit of verbal recall after a left internal cerebral vein infarct]

A case of unilateral infarct in the territory of the left internal cerebral vein, severely disturbing cognitive processes, and more especially recall in verbal memory, is reported. This 22-year-old patient survived a left thalamic and striato-capsular infarct related to a straight sinus and left internal cerebral vein thrombosis. Motor and functional recovery was fair, despite late dystonia. At the secondary phase post-stroke, cognitive disorders were severe, including increased short-term forgetting and episodic (anterograde and retrograde) and semantic amnesia. One year later, a residual deficit of verbal recall was observed, which participated in the anterograde and retrograde amnesia. Recognition was well preserved. This case showed that: (1) internal cerebral vein thrombosis can have severe consequences on cognition and memory, and that late prognosis is not as fair as has been previously reported in selected patients, and (2) left diencephalic structures are specifically associated with recollection of verbal information from long-term memory.

Helical CT for the follow-up of cervical internal carotid artery dissections

PURPOSE

The aim of this study was to assess the changes over time of internal carotid artery (ICA) dissections by using helical CT.

METHODS

Twenty-seven patients with 30 angiographically proved ICA dissections were followed up with helical CT at 7 to 62 months (median, 24 months) after conventional angiography. CT scans, analyzed independently by two radiologists in a blinded fashion, were evaluated for the presence of mural thickening, aneurysmal formation, and arterial occlusion. In cases without persisting occlusion or aneurysm, we measured the external diameter of the ICA at its upper segment.

RESULTS

The interobserver agreement was good. Mild mural thickening was observed in four cases of 30 previously dissected ICAs. All stenotic and nearly occlusive dissections without an aneurysm (n = 12) reverted to a normal or nearly normal diameter. Half the aneurysms resolved spontaneously (four of eight). Of the 10 occluded ICAs, nine were recanalized, but their external diameter was significantly smaller than that of normal carotid arteries, and a hypoplastic appearance was seen throughout the cervical segment of the ICA in three cases.

CONCLUSION

Most arterial lesions tend to improve or disappear spontaneously, but persisting ICA narrowing may be observed in the late course of occlusive-type dissections.

Duplication of the pituitary gland in a newborn with median cleft face syndrome and nasal teratoma

A newborn suffered immediate neonatal respiratory distress because of an obstructive, soft-tissue nasal mass. Clinical examination revealed a cleft palate with a protruding polypoid mass. CT and MRI showed a heterogeneous nasopharyngeal mass and associated intracranial abnormalities - duplication of the hypophysis and hypoplasia of the corpus callosum. Duplication of the hypophysis is a very rare malformation, only 13 cases having been previously described. The suggested pathogenesis is duplication of the prechordal plate and anterior end of the notochord during early embryological development.

Cerebral magnetic resonance imaging in patients with or without antiphospholipid antibodies

OBJECTIVE

To determine in patients with systemic lupus erythematosus (SLE) or with primary antiphospholipid syndrome (PAPS) the prevalence of cerebral magnetic resonance imaging changes (MRI) and the relationship with antiphospholipid antibodies.

METHODS

Twenty-nine consecutive SLE patients, 24 PAPS patients and 31 healthy controls were prospectively included in the study and underwent MRI Scan over a 1-year period. MRI scans were analyzed separately by a neuroradiologist for white matter changes [periventricular hyperintensity (PVH) (0-6 scale), deep white matter hyperintensity (WMH) (0-24 scale)], and one neurologist for cerebral atrophy (0-39 scale) and stroke subtypes. Statistical assessment consisted of a discriminant analysis performed with SAS-package with MRI data as dependent variables and, as independent variables, age, sex, arterial hypertension, diabetes mellitus, cardiopathy, migraine, neurological symptoms, antiphospholipid antibodies, SLE, steroid treatment.

RESULTS

The prevalence of cerebral atrophy was increased in both SLE and PAPS groups relative to controls. PVH and WMH scores were significantly higher in SLE and PAPS than in controls. Focal infarct did not differ in the SLE group when compared with PAPS. PVH and WMH scores were significantly higher in patients with neurological symptoms. Using a correlation test we found a weak significant correlation between cerebral atrophy and lupus anticoagulant. The multivariate analysis found only three independent variables related to PVH and WMH: age, the diagnosis of SLE and cerebral atrophy.

CONCLUSIONS

Age, presence of SLE and presence of neurological symptoms were independently related with WMH and PVH, but not antiphospholipid antibodies.

Explicit memory in frontotemporal dementia: the role of medial temporal atrophy

In our memory clinic experience, memory impairment differs widely in patients with frontotemporal dementia (FTD). We searched for a correlation between explicit memory disturbance assessed with the Grober and Buschke test and medial temporal atrophy on CT scan in 22 consecutive patients with FTD. Five of the 22 patients had a medial temporal lobe (MTL) atrophy. There was no significant difference between the two groups for the demographic characteristics. Free recall, cued recall and the learning curve were significantly better in patients without MTL atrophy. The patients with MTL atrophy made more intrusions. We found a positive correlation between total recall and cued recall and the mean of medial temporal lobe measurement. These results are in agreement with the role of the hippocampal formation in the memory process. In our group, the ratio of patients with MTL atrophy is similar to the ratio of Pick's disease in frontotemporal dementia. In histological series more severe hippocampal atrophy are reported in Pick's disease. Therefore MTL atrophy on CT scan could be a marker of Pick's disease in FTD.

Unusual MRI findings in grey matter heterotopia

We report unusual MRI patterns in patients with grey matter heterotopia. Standard T1- and T2-weighted spin-echo and inversion-recovery sequences were used in 22 patients presenting with seizures or developmental delay. The images were reviewed for signal change surrounding white matter and for atypical size, morphology or topography. We found 10 cases of subependymal heterotopias 11 of focal subcortical heterotopia and of diffuse subcortical heterotopia. On clinical or MRI grounds, 8 cases were considered unusual: 2 of the subependymal type, 2 of focal subcortical heterotopia with white matter abnormalities, 2 of focal subcortical heterotopia with no clinicoradiological correlation 1 of extensive hemispheric subcortical heterotopia and 1 of diffuse subcortical heterotopia confined to the frontal lobe. The classical classification of heterotopia enables easy radiological diagnosis even in cases with unusual patterns. In some cases, heterogeneity and high signal in surrounding white matter can be found. Cortical dysplasia is the most frequent associated malformation.

[Retrograde memory after rupture of aneurysms of the anterior communicating artery]

The aim of this study was to investigate deficits of retrograde memory, semantic, autobiographical, and for famous events, associated with prefrontal, cingulate and subcortical lesions resulting from anterior communicating artery rupture. Analyses were performed during the secondary phase post-stroke in 16 patients, and performances were compared to those of an equivalent number of matched control subjects. Semantic investigations revealed a significant deficit in each task using evocation, more especially categorical and literal evocations, and the verbal subtests of the WAIS-R: vocabulary, information, comprehension, and similarities. Furthermore, the capacity to categories was preserved. The Crovitz paradigm, which evaluated the autobiographical memory showed a severe deficit in the evocation of events associated with a precise context in place and moreover in time, with a clear tendency to produce semantic responses, but without significant increase in confabulations. The questionnaire on famous events (1936-1985) did not document deficit in recognition and recall. Furthermore, the patients disorder was more severe in learning new information. Memory disorders were best explained by the severity of lesions in the medio-basal frontal and cingulate cortices, but also by the subcortical injury. Significant correlations were observed between the retrograde memory performance and "frontal" tasks, more especially the WCST; however, similar relations were also documented between learning new information and "frontal" performance. These data suggest that retrograde amnesia results from a selective impairment in accessing old memory representations, and that cognitive processes more specifically altered have tight relations with the capacity to organize the search and to shift.

[Study of the carotid artery bifurcation using a helical scanner]

Helical CT is a new technology leading to a rapid acquisition of a large volume during the peak of intravascular enhancement. Indications are large in vascular pathology due to the possibilities of three dimensional (3D) reconstructions providing angiogram-like images. To assess carotid bifurcations, this examination needs the choice of multiple parameters for acquisition (collimation, table speed, can time), injection (volume of contrast material, rate, scan delay) and reconstruction (increment, field of view). Post processing is performed on an independent workstation. Helical CT provides a reliable analysis of carotid artery stenosis. Voluminous calcified plaques constitute the main limiting factor preventing image analysis on the 3D reconstructions. Furthermore, image reconstructions require a long time, study of carotid siphons remains inefficient and examination of the circle of Willis cannot be performed in the same time.

Medial temporal lobe atrophy in memory disorders

Medial temporal lobe atrophy determined by temporal lobe oriented computed tomography (CT), 1 year before death, is strongly associated with histopathologically confirmed Alzheimer's disease (AD). The aim of this study was to assess the diagnostic accuracy of medial temporal lobe measurement for the diagnosis of AD in patients referred to a memory disorders clinic, especially those at an early stage of the disease. CT oriented to the temporal lobe was performed in 333 subjects aged 41-93 years consecutively recruited in a Memory Disorders Clinic: 124 had probable AD, Mini Mental State score (MMS) = 17 (8); 50 possible AD [MMS = 21 (5)]; and 119 patients had miscellaneous memory disorders [MMS = 22 (7): frontotemporal lobe dementia, subcortical dementia, cortical Lewy body disease, vascular dementia, Korsakoff syndrome, focal atrophy, etc.]. There were also 19 anxious/depressed patients [MMS = 29 (1)] with normal performance on memory tests, and 21 controls. The minimum width of the medial temporal lobe was measured. The best cut-off to distinguish AD patients from non-AD patients was 11.5 mm, in agreement with data in the literature. At this threshold, 84% of probable AD patients had a positive test and 90% of controls and anxious/depressed patients had a negative test. For the diagnosis of probable AD, sensitivity of the measurement was 0.81, specificity 0.95, predictive positive value 0.99, predictive negative value 0.45, and diagnostic accuracy 0.83. The test was positive in half the possible AD patients, and half those with miscellaneous memory disorders. It was negative in all anxious/depressed patients. Therefore, temporal lobe oriented CT might be a valuable tool for assessment of medial temporal lobe atrophy in AD routine practice.

Arterial ischemic strokes associated with pregnancy and puerperium

Physiological changes occurring during pregnancy and puerperium may increase the risk of stroke. However, the incidence rate of ischemic stroke is of 3.8 to 5 in 100,000 pregnancies, i.e. quite similar to that of ischemic strokes occurring in non pregnant women of child bearing age. Whereas eclampsia, choriocarcinoma and amniotic emboli occur only during pregnancy or puerperium, peripartum cardiomyopathy and benign cerebral angiopathy are less specific. All other causes of cerebral ischemia may also occur during pregnancy and puerperium. The management of an ischemic stroke should not differ between pregnant and non pregnant women of child bearing age. Strokes associated with pregnancy require a complete diagnostic work-up including angiography if necessary. Low doses of aspirin (60-80 mg/d) can be used after 3 months of pregnancy. Heparin is the anticoagulant of choice during pregnancy, but warfarin may be used between 13 and 36 weeks of gestation; heparin and warfarin can be used during breast feeding. There is no neurological reason to recommend a systematic use of cesarean section. Subsequent prescription of oral contraceptive therapy is not recommended except in patients with a definite cause of ischemic stroke which is not influenced by hormones.

Cervical artery dissections

Cervical artery dissection (CAD) accounts for up to one fifth of ischemic strokes occurring before 45 years. Their increasing recognition is probably due to an increased clinical awareness of this condition in patients with painful ischemic events. The internal carotid artery is the most commonly affected vessel. Cerebral ischemia is the most serious consequence of a CAD. It may be due to hemodynamic factors or emboli. The enlargement of the artery may lead to a direct compression of the lower cranial nerves. CAD typically occurs in young adults with a mean age of 40 years with a male:female ratio of 1.5. After exclusion of traumatic cases, the average annual incidence rate of CAD is 2.6 per 100,000, but the reported incidence figures in the literature are likely to be an underestimation of the incidence of CAD. A spontaneous dissection is assumed when no or only minor trauma preceded the onset. However, the differentiation between spontaneous and traumatic dissections is artificial because of a continuum between both forms. The pathogenesis of dissections remains unknown in most cases. However, traumas and primary diseases of the arterial wall are the main predisposing factors. The clinical presentation of spontaneous dissections of the internal carotid artery includes cerebral ischemia, cervical or cranial pain, Horner's syndrome and cranial nerve palsy; CAD may also be silent. Brainstem ischemic deficits and occipital pain are the most common findings in vertebral artery dissections, but these features may be biased because the most benign and the most severe cases may escape detection. The favorable natural history of CAD emphasizes the need for a noninvasive approach to the detection, monitoring and follow-up. This noninvasive approach can be obtained by means of CT scan, MRI, magnetic resonance angiography and ultrasonography, although angiography remains the gold standard for the diagnosis of arterial dissections. Follow-up studies suggest a fairly good overall prognosis in adults and in children. In many centers, CAD are treated by heparin at the acute stage, although the benefit of such a potentially dangerous treatment has never been proven by a randomized trial.

[Dystonia and tremor in bilateral lesion of the posterior mesencephalon and the vermis]

The aim of this study is to report the association of diffuse dystonia and tremor in a bilateral and extended lesion of the posterior mesencephalon. After surgery on a meningioma of the upper part of the fourth ventricle, this patient presented with facial dystonia, predominating on orbicularis muscles and peribuccal area, and limb dystonia, with tonic extension of fingers and first toes. The tremor was associated with a rhythmic and most often alternate agonist-antagonist muscular activation, whose frequency varied from 3 to 7 Hz. These disorders were increased by the standing position, voluntary movement, somatosensory stimulations, stress or emotion. Pyramidal and somatosensory tracts were spared. Therapeutic trials showed that both the dystonia and tremor were improved by subcutaneous injection of apomorphine, the dystonia by trihexyphenidyle, and the tremor by carbamazepine and propranolol, but not by levodopa and benserazide. The cerebral blood flow study using HMPAO showed a relatively important activity on the cerebellum, which could play a role in the onset of these disorders.

[Easy creation of a kit of radiologic images with Microsoft Visual Basic]

As computer media have a well accepted role in the medical world, we suggest to residents and assistants specialized in imaging, an easy, evolutive and low-cost computer-based method, that allows to build up a picture data bank for use as a teaching tool. We join to this article, the output of our interface program.

[Analysis and course of cognitive deficits after rupture of aneurysms of the anterior communicating artery]

The aim of this study is to investigate general intellectual and memory performances at the secondary (3 weeks to 4.5 months) and late (10 to 16 months) stages following rupture of anterior communicating artery aneurysms (AACA). Twenty one patients presenting with selective lesion within frontal, or cingulate, callosal, caudate, basal forebrain areas were evaluated. At the secondary stage, the analysis of the general intellectual capacities revealed a drop of performance, prominent on performance IQ, which was more severe than the learning deficit. Specific cognitive evaluations revealed increase of the execution time, but performance was relatively preserved: in the Stroop test, focused attention disorder was moderate: the modified Wisconsin Card Sorting test was correctly performed in most cases; significant deficits of verbal short-term memory, long-term verbal and visuo-spatial learning, and access to semantic memory were observed. At the late stage, general intellectual performance improved, but did not reached the estimated prelesional level in most cases; specific cognitive disorders had most often disappeared. Most performances were best explained by the severity of lesions in the left cingulate cortex and corpus callosum area. These results show that the cognitive profile of AACA patients is different from classical descriptions of the "amnesic syndrome", and is also different at the secondary and late stages; this evolution has to be taken into account in studies describing cognitive deficits of such patients, or comparing them with others presenting with "annesic syndrome".

Risk factors and leukoaraiosis in stroke patients

OBJECTIVES

Although leukoaraosis (LA) is a common CT findings, its pathogenesis remains debated: if small-artery pathology may explain in some cases white matter changes, many other factors, such as hemodynamic perturbations, might also lead to LA. To test these hypothesis, we determined the types of cerebrovascular risk factors associated with leukoaraosis in consecutive patients with acute cerebrovascular event.

PATIENTS AND METHODS

Using CT-scans, we prospectively studied in 610 patients consecutively admitted for an acute cerebral event, the relation between LA and the following cerebrovascular risk factors: age, sex, arterial hypertension, diabetes mellitus, hyperlipemia, alcohol consumption, birth contraceptive pills, previous transient ischemic attack or stroke, migraine, atrial fibrillation, valvulopathy, coronaropathy, left ventricular hypertrophy, stenosis of the internal carotid artery, by means of a multiple linear regression. Relation with cerebral atrophy was also evaluated.

RESULTS

We found LA scores to depend on increasing age (p = 0.0001), female sex (p = 0.0146), history of stroke or TIA (p = 0.0051), history or current atrial fibrillation (p = 0.0083), increasing cerebral atrophy score (p = 0.0001), absence of hyperlipemia (p = 0.0003) and absence of alcohol consumption higher than 300 g/week (p = 0.0398).

CONCLUSION

Our findings do not support the hypothesis that, in stroke patients, LA share similar risk factors than small-vessel disease; other cerebrovascular risk factors may also contribute to LA, perhaps because of decreased cerebral blood flow.

[Moyamoya associated with Down syndrome]

We present a case of a six-year-old girl with Down Syndrom who developed recurrent ischemic strokes. Cerebral angiography demonstrated a supraclinoid stenosis of the right internal artery, an occlusion of the left supraclinoid internal cerebral artery and dilated collateral vessels, consistent with Moyamoya disease. We emphasize the increased frequency of Moyamoya in patients with Down Syndrome and also the most important pathophysiologic, clinical and radiological findings of this disease.

[Sarcoidosis of the central nervous system: clinical and radiological polymorphism]

Central nervous system (CNS) neurosarcoidosis was considered to be infrequent. Clinical and radiological polymorphism explained the delay before diagnosis. With magnetic resonance imaging (MRI), diagnosis is more easily performed, especially in paucisymptomatic cases. A review of the most important clinical and radiological studies and three personal cases are reported. This underlines variable characteristics of hemispheric localizations, especially pseudotumoral forms.

[MRI aspect and course of supra-tentorial sarcoidosic lesions]

Central nervous system lesions resulting from sarcoidosis occur in 5% of cases, but supratentorial mass lesions are uncommon. We report 3 cases of intracranial pseudo-tumoral lesions, due to sarcoidosis: 1 woman and 2 men. Clinical features included left facial myoclonus, headache and vertigo, right hemiparesis and unique general seizure. Sarcoidosis was diagnosed upon conjonctival biopsy in the first case, infiltrative lesions of the lungs and mediastinal lymph nodes in the second case, and intracerebral lesion plus lymph nodes biopsies in the last case. In the first case, CT scan and MRI images showed diffuse subcortical high signal, suggesting pachymeningitis with vasogenic oedema. In the second case, GT scan and MRI revealed numerous small granuloma in the left rolandic area, and one in the striatum. In the third case, CT scan showed an enlargement of the left temporal horn, due to an enhanced left periventricular lesion. MRI with gadolinium showed that the lesion encircled the ventricle horn. In all cases, clinical and radiological improvement was obtained after corticoid therapy.

White matter magnetic resonance imaging hyperintensity in Alzheimer's disease: correlations with corpus callosum atrophy

We have previously demonstrated with MRI that as well as marked white matter involvement in late-onset Alzheimer's disease (AD), atrophy of the corpus callosum may also be present. This finding prompted us to study possible correlations between atrophy of the corpus callosum and white matter hyperintensity (WMH) and between white matter lesions and the severity of the disease. We compared the corpus callosum and white matter lesions on MRI from 15 AD patients and 15 controls. The white matter lesions were scored according to the Scheltens' rating scale. We found a significant reduction of the area of the corpus callosum and more severe white matter lesions in AD patients than in controls. Both atrophy of the corpus callosum and the severity of lesions depended mainly on the diagnosis of senile dementia of the Alzheimer type and on age but not on the diagnosis of presenile AD. We demonstrated a negative correlation between white matter lesions scores and areas of corpus callosum in AD patients and no correlation between the white matter lesions and the severity of the disease. We demonstrated that white matter lesions including WMH and atrophy of the corpus callosum are more frequent in AD than in controls. The predominance of white matter lesions in senile AD may be explained by the combination of aging and disease processes.

Helical CT for the diagnosis of extracranial internal carotid artery dissection

BACKGROUND AND PURPOSE

We attempted to evaluate the sensitivity of helical CT for the diagnosis of extracranial internal carotid artery (ICA) dissection.

METHODS

Sixteen consecutive patients with 18 angiographically confirmed extracranial ICA dissections were studied with a helical CT protocol with large-volume acquisition and thin axial slice reconstructions. A control group including normal and atherosclerotic ICAs was formed for comparison, and a blind interpretation of CT images was made by two observers. We evaluated the presence of stenosis, eccentric lumen, mural thickening, aneurysm, occlusion, and annular contrast enhancement. When the artery seemed to be occluded, we measured the external diameter of the ICA (1) on the occluded side, at its upper portion and most enlarged level, (2) at its lower portion, beyond the bulb, and (3) on the contralateral side, at is upper portion.

RESULTS

Interobserver agreement was good except for the presence of annular contrast enhancement. In the stenotic dissection group (n=12), the presence of a narrowed eccentric lumen at the upper portion of the ICA on axial CT images was classified correctly in all cases (sensitivity, 100%; specificity, 100%). An arterial wall thickening was seen in all cases of dissection but also in three cases of the control group. In the occlusive dissection group (n=6), the enlargement of the dissected artery was the best criterion (sensitivity, 100%, specificity, 100%) for occlusive dissection.

CONCLUSIONS

Helical CT seems to be a reliable method for evaluating extracranial ICA dissection. The analysis of the residual arterial lumen and the measurement of the external diameter of the carotid artery were the best criteria for the diagnosis. Further studies with larger groups are required to determine whether ICA dissections might be diagnosed using helical CT as a first procedure.