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J C Froment

Publications and source records attributed to J C Froment.

At least 55 records · Page 3Linked to original sources
PubMed1997

Assessment of cerebrovascular reactivity by dynamic susceptibility contrast-enhanced MR imaging.

In patients with cerebrovascular disease the acetazolamide (ACZ) test is performed to evaluate the decrease in cerebral perfusion pressure (CPP) through the investigation of the vasomotor reactivity (VMR). This latter is currently assessed with ACZ with several methods. Recently, magnetic resonance imaging (MRI) techniques have been developed that are sensitive to stimulus-induced changes in blood flow. Dynamic susceptibility contrast material-enhanced gradient-echo MRI techniques (DSC-MRI) might be an attractive tool to assess VMR. We aimed to test the ability of DSC-MRI in the assessment of VMR. Relative hemodynamic parameters rCBV, MTT, and rCBF were evaluated at baseline after the first injection of gadopentetate dimeglumine and 10 min after the intravenous administration of ACZ (1 g) with a second bolus of contrast agent. Assessment of hemodynamic parameters was performed over the whole hemisphere and also within regions of interest. The significances of the mean differences, before and after ACZ, were assessed with repeated-measures ANOVA with two within factors: laterality (right-left) and ACZ. DSC-MRI with ACZ test was performed in ten healthy controls (aged 51.4+/-16.2 years). The cerebral hemispheric ratio for the three parameters (cerebral blood volume (CBV), mean transit time (MTT), and cerebral blood flow (CBF)) ranged between 1.01 and 1.03. The mean gray matter-to-white matter ratio for CBV, CBF and MTT were 2.44, 2.41 and 1.05, respectively. As the laterality effect was not significant, left and right hemispheric values were averaged. A significant increase of all hemodynamic parameters was observed after ACZ (P<0.01-0.001). The same changes for CBV, CBF and MTT were observed after ACZ according to the regions of interest (P<0.006-0.015). DSC-MRI is a non-invasive method which enables the assessment of VMR. This technique may be added to any conventional MRI in order to detect a hemodynamic impact of an ICA stenosis. Therefore, it might be useful in determining the appropriate management when the indication for surgical versus medical therapy is in question.

Acetazolamide↗
PubMed1997

Auditory cortex activation in deaf subjects during cochlear electrical stimulation. Evaluation by functional magnetic resonance imaging.

RATIONALE AND OBJECTIVES: The authors detect activation in the auditory cortex during cochlear electrical stimulation in deaf patients using functional magnetic resonance (MR) imaging. METHODS: Stimulating electrode was inserted gently under local anesthesia close to the round window membrane of the cochlea in seven cochlear implant candidates. These patients suffered from postlingual-acquired deafness. Four patients were stimulated above the electrical perception threshold and three below the electrical discomfort threshold. Functional scans (fast low-angle shot 91 mseconds/60 mseconds) were acquired in an oblique axial plane running parallel to the sylvian fissure. Four consecutive series of six images were obtained in 6 minutes. The acquisition time of each image was 15 seconds. RESULTS: During electrical cochlear stimulation below the discomfort threshold, the three patients described "auditory" sensations with activation of the superior temporal regions. In two patients with electrical stimulation of the left ear, the maximum signal intensity increased by 8.42% in the right auditory cortex and 5.69% in the left. In one patient with a right electrical stimulation only the left cortex was activated. Electrical cochlear stimulation above the perception threshold induces no significant activation in the auditory cortex. CONCLUSION: Functioning MR imaging can detect activation in the auditory cortex during cochlear electrical stimulation in deaf patients using a conventional 1.5-tesla system in a routine hospital environment. Further studies are needed to investigate its usefulness in clinical practice.

Adult↗
PubMed1997

Therapeutic effect of mitoxantrone combined with methylprednisolone in multiple sclerosis: a randomised multicentre study of active disease using MRI and clinical criteria.

OBJECTIVE: To evaluate the efficiency of mitoxantrone in multiple sclerosis. METHODS: Forty two patients with confirmed multiple sclerosis, selected as having a very active disease on clinical and MRI criteria were randomised to receive either mitoxantrone (20 mg intravenously (IV) monthly) and methylprednisolone (1 g iv monthly) or methylprednisolone alone over six months. In the steroid alone group five patients dropped out due to severe exacerbation. RESULTS: Blinded analysis of MRI data showed significantly more patients with no new enhancing lesions in the mitoxantrone group compared with the steroid alone group, (90% v 31%, P < 0.001). In the mitoxantrone group there was a month by month decrease almost to zero in the number of new enhancing lesions, and in the total number of enhancing lesions, whereas both remained high in the steroid alone group. The differences were significant for both indices at all months from 1-6. Unblinded clinical assessments showed a significant improvement in change in EDSS at months 2-6 in the mitoxantrone group, with a final mean improvement of more than one point (-1.1 v + 0.3; P < 0.001). There was a significant reduction in the number of relapses (7 v 31; P < 0.01), and an increase in the number of patients free of exacerbation (14 v 7; P < 0.05). CONCLUSION: In this selected group of patients with multiple sclerosis with very active disease, mitoxantrone combined with methylprednisolone was effective in improving both clinical and MRI indices of disease activity over a period of six months whereas methylprednisolone alone was not. Further double blinded long term studies are needed to properly evaluate the effect of mitoxantrone on progression in disability.

Adjuvants, Immunologic↗
PubMed1997

Brain glucose metabolism with [18F]-fluorodeoxyglucose and positron emission tomography before and after surgical resection of epileptogenic cavernous angiomas.

Surgery of cavernous angiomas is often proposed due to the epileptogenic and hemorrhagic potential of this lesion. Little information is available on the impact of surgical resection on brain metabolism, locally or at a distance from the lesion. Fifteen patients presenting with a cavernoma and epileptic seizures underwent positron emission tomography examinations before and 1 year after surgical resection. We studied the quantitative cerebral metabolic rate of glucose (CMRGlu) with [18F]-fluorodeoxyglucose. The global brain CMRGlu remained unchanged after surgery. There was a significant decrease of metabolism in the lesion hemisphere, which remained unchanged after surgery. The perilesional regions were less metabolic than the contralateral ones and less metabolic than remote regions within the same hemisphere, before and after surgery. The absence of pre- to postsurgical variations suggests that the metabolic consequences of the lesion are maintained despite the surgical procedure during long-term follow-up studies.

Brain↗
PubMed1997

[An experimental study of the treatment of aneurysms using an intravascular prosthesis].

Intracranial aneurysms occur frequently with the risk of major damage. Neurosurgery or endovascular techniques can be used for treatment. Current techniques are not well adapted for aneurysms with a wide implantation (or neck). The aim of this experimental work was to study a technique for treating aneurysms which can be used for wide neck aneurysms. A metal stent is implanted facing the neck of the aneurysm to allow occlusion. In the first part of the study, the stent was inserted alone. Ten aneurysms were created surgically in five dogs. The stents were positioned facing seven of the ten aneurysms. The stent led to immediate occlusion of the aneurysm in six of the cases. One aneurysm remained patent despite the correct position of the stent. One dog developed secondary thrombosis of the carotid. Three dogs have been followed for sixty days after insertion of the stent. Two aneurysms thrombosed and one was patent. Since these results were less than satisfactory, a second part of the study was undertaken to cover the stent with a fragment of the autologous vein. Results in five aneurysms, evaluated three and eight weeks after treatment, showed partial or total repermeabilization of the aneurysms. In the third part of the study, we associated stents and detachable coils. Twelve aneurysms of the carotid artery in pigs were thrombosed and two aneurysms were completely occluded after stent implantation. In the nine other cases, the aneurysms were completely occluded after stent implantation. In the nine other cases, the aneurysms remained patent despite the stent and treatment was then completed with a coil. Six of the animals have been followed for thirteen weeks. One carotid artery thrombosed. In the five other cases, the carotid arteries were patent and the aneurysms were occluded at the control angiogram. Histology results showed the presence of a fibromuscular endothelialized neointima at the neck of the aneurysm in four of the five cases. The technique described here could be proposed for the treatment of wide-neck aneurysms implanted low on the carotid artery in man. Improvements should render the system more flexible.

Aneurysm↗
PubMed1996

A controlled positron emission tomography study of obsessive and neutral auditory stimulation in obsessive-compulsive disorder with checking rituals.

Ten nondepressed patients with obsessive-compulsive disorder (OCD) who were characterized by predominant checking rituals were compared with 10 age- and sex-matched control subjects. Hemispheric and regional cerebral blood flow levels (rCBF) were measured with positron emission tomography (H2 15O) across four conditions: rest, auditory stimulation with idiosyncratic normal or abnormal obsession, auditory stimulation with neutral verbal stimuli, and rest. Order of neutral and obsessive stimulation was randomized. Higher subjective responses to obsessive than to neutral stimulation were found in both groups; subjective response was higher in OCD patients when obsessive stimulation was presented first. A four-way analysis of variance (group x stimulation order x hemisphere x condition [neutral or obsessive stimulation]) was performed on stimulation minus rest normalized rCBF values. Control subjects had significantly higher rCBF in the thalamus and putamen. A trend toward higher rCBF in OCD patients was found in the superior temporal regions. When neutral stimulation was presented first, rCBF was significantly higher in the caudate region of control subjects. Obsessive stimulation was associated with higher rCBF than neutral stimulation in orbitofrontal regions in both groups of subjects. Under obsessive stimulation, superior temporal and orbitofrontal activities were correlated in OCD patients but not in control subjects. Our study suggests specific abnormalities of information processing in the basal ganglia and temporal structures of compulsive checkers.

Adult↗
PubMed1996

Late MR follow-up of hypothalamic hamartomas.

The absence of changes over time in the diagnostic features of suspected hypothalamic hamartomas is of paramount importance. Since magnetic resonance (MR) imaging is very sensitive to modifications in the brain parenchyma, a late MR follow-up study was performed in five children. In all cases, the diagnosis of hypothalamic hamartoma has been suspected on the basis of the association of central precocious puberty and the presence of a mass in the inferior aspect of the hypothalamus, demonstrated on previous MR studies. Late MR evaluation (after a mean of 39 months) demonstrated stability of the lesions in shape, size, and signal intensity. In three cases the lesions demonstrated a rim of isointense signal with a hyperintense center on T2-weighted sequences. In two cases a Chiari I malformation was found in association with the hypothalamic malformation. In one case a pineal cyst was demonstrated. These unusual findings are discussed. Late MR follow-up showed the absence of changes in the lesions over time, allowing the diagnosis to be confirmed.

Arnold-Chiari Malformation↗
PubMed1996

Positron emission tomography metabolic data corrected for cortical atrophy using magnetic resonance imaging.

The correct interpretation of clinical positron emission tomography (PET) data depends largely on the physical limits of the PET scanner. The partial volume effect (PVE) is related to the size of the studied object compared to the spatial resolution. It represents one of the most important limiting factors in quantitative data analysis. This effect is increased in the case of atrophy, as in patients with Alzheimer disease (AD), and it influences measurement of the metabolic reduction generally seen in cerebral degeneration. In this case, interpretation can be biased, because cortical activity will be underestimated due to the atrophy. In general, anatomical images of AD patients have shown diffuse atrophy, while PET studies have found widespread hypometabolism affecting the parietal and temporal lobes. Although hypometabolic areas usually correspond to atrophic regions, they also occur without such changes. Thus, the aim is to differentiate authentic hypometabolism (decrease of glucose consumption per unit volume of gray matter) from that due to PVE from atrophy (cell loss). Consequently, we are using a method for three-dimensional (3D) correction of human PET data with 3D magnetic resonance imaging (MRI). We measured atrophy and metabolism by using both T1-weighted MR images and high and medium resolution PET scans. We injected 12 patients and controls with [18F]fluorodeoxyglucose for glucose consumption measurements. Atrophy was estimated in the following way. We isolated the cerebral structures, using a segmentation technique on the MRI scans, into gray matter (GM), white matter, and cerebrospinal fluid. We superimposed the PET images onto the MR images to obtain anatomo-functional correlations. We degraded the segmented MR images to the resolution of the PET images by a convolution process to create a PET image correction map. We corrected the metabolic PET data for the PVE. We studied the cerebral metabolic rate of glucose in the GM where metabolic variation is the most relevant to AD. By dealing with problems relating to the sensitivity to the segmentation and to the PET-MRI coregistration, computation of MRI convolution processes provided the degree of PVE on a pixel-by-pixel basis, allowing correction of hypometabolisms contained in GM PET values. Global cortical metabolism increased after correction for PVE by, on average, 29 and 24% for tomographs acquired with medium (TTV03 LETI) and high (ECAT 953B CTI/Siemens) resolution, respectively, whereas the cortical metabolism increased by 75 and 65% for the respective tomographs in AD patients. The difference of metabolism between scans after correction for PVE was less than before correction, decreasing from 31 to 17%. This difference was most marked in the frontal and temporal lobes. Fusion imaging allowed correction for PVE in metabolic data using 3D MRI and determination of whether a change in the apparent radiotracer concentration in PET data reflected an alteration in GM volume, a change in radiotracer concentration per unit volume of GM, or both.

Adult↗
PubMed1996

Hemodynamic parameter assessment with dynamic susceptibility contrast magnetic resonance imaging in unilateral symptomatic internal carotid artery occlusion.

BACKGROUND AND PURPOSE: Hemodynamic parameters such as regional cerebral blood volume (rCBV), mean transit time (MTT), and regional cerebral blood flow (rCBF) can be assessed by dynamic susceptibility contrast MRI. The aim of the present study was to apply this method in patients who had symptomatic unilateral internal carotid artery occlusion. METHODS: Relative hemodynamic parameters (rCBV, MTT, and rCBF) were evaluated on the occluded side and thus compared with contralateral hemispheric values. We also attempted to detect any relationship between collateral flow and the hemodynamic parameters. RESULTS: Although rCBV was clearly increased in five patients over the whole hemisphere, we did not observe a statistically significant difference regarding the whole sample between sides (mean rCBV, 14.1 +/- 4.58 on the occluded side versus 11.8 +/- 2.99 on the contralateral side, P>.10). MTT was clearly increased on the occluded side (mean MTT, 4.29 +/- 0.83 on the lesion side versus 3.14 +/- 0.81 on the contralateral side, P<.010). A statistically significant decrease of rCBF on the occluded side was observed (mean rCBF, 3.27 +/- 0.73 versus 3.93 +/- 1.03 on the contralateral side; P<.01). CONCLUSIONS: A significant hemodynamic compromise in patients who had unilateral symptomatic carotid occlusion was observed according to CBF and MTT values. This approach might be promising in the understanding of cerebral hemodynamics in patients with vascular disorders.

Aged↗
PubMed1996

Open trial of intravenous tissue plasminogen activator in acute carotid territory stroke. Correlations of outcome with clinical and radiological data.

BACKGROUND AND PURPOSE: Pilot studies using early thrombolytic therapy in stroke have suggested that recombinant tissue plasminogen activator (rTPA) might be effective. While large, double-blind, randomized studies are needed, open trials could generate hypotheses concerning (1) the clinical correlations of outcome, (2) the significance of CT scan data during the first week, and (3) the use of adjunctive therapies. METHODS: We performed an open trial of intravenous rTPA on patients referred to our emergency service with all types of ischemic stroke in the carotid territory. All patients between 20 and 81 years hospitalized during 1994 with completed stroke in the internal carotid artery territory and a baseline Scandinavian Stroke Scale score lower than 48, even with severe disturbances of consciousness, were included. The inclusion time was within 7 hours after stroke onset. A 0.8-mg/kg dose of rTPA was infused for 90 minutes. Intravenous heparin was given either immediately at efficient dosage or after 24 hours. Mannitol was used in patients with severe presentation. The Scandinavian Stroke Scale evaluation was done at baseline, 3 hours, and 1, 7, 30, and 90 days. The CT scan was performed before the treatment and at days 1 (24 +/- 6 hours) and 7. RESULTS: Forty-three consecutive patients met the criteria of the protocol. The mean age at inclusion was 65 +/- 10.4 years, and the mean interval to treatment was 232 +/- 79 minutes. At day 90, 25 patients (58.1%) exhibited a complete regression of symptoms, and 3 had moderate neurological sequelae. Thirteen patients had severe neurological sequelae, 11 with infarcts and 2 with secondary parenchymal hematomas. Two patients died (4.6%), 1 with hematoma. The overall hematoma rate was 6.9%. Excellent outcome at day 90 was significantly correlated with major neurological improvement at day 1. Intravenous immediate heparin versus delayed heparin after 24 hours improved the ischemic outcome but not the overall outcome. Reinfarction syndromes after major neurological improvement, likely to be rethrombosis syndromes, were observed in 3 patients (6.9%). For the day 1 CT scan, poor outcome was associated with the presence of structured and homogeneous hypodensities likely to represent classic infarcts, as confirmed by day 7 CT scan. Conversely, total recovery was significantly associated with the absence of any image or with unstructured hypodensities, a particular type of image characterized by its heterogeneous darkness and often polylobar shape. This type of image disappeared at day 7 in 17.6% of the cases and is likely to represent reperfusion images and/or incomplete ischemic damage. CONCLUSIONS: The results obtained in this open, small study suggest safety and effectiveness of rTPA thrombolysis at the dose of 0.8 mg/kg within 7 hours in acute strokes of the carotid territory, including highly serious baseline neurological presentations, until age 81 years and under special therapeutic conditions. Complete recovery is significantly associated with major neurological improvement during the first 24 hours and the presence of a particular type of image at day 1 CT scan characterized by an unstructured hypodensity, often polylobar and heterogeneous, which is likely to correspond to reperfusion images.

Adult↗
PubMed1996

Efficacy and safety of iobitridol versus iohexol for contrast-enhanced CT of the head.

PURPOSE: The efficacy and adverse reactions of iobitridol versus iohexol in contrast-enhanced CT (CECT) of the head were investigated. MATERIAL AND METHODS: This double-blind randomized parallel study compared the clinical and biological safety of iobitridol and iohexol (350 mgI/ml), administered intravenously (1 ml/kg) to 276 patients undergoing CECT of the head. Vital signs were assessed just before after injection, and 24 hours after. A biologic examination was performed before and after injection. Both groups were comparable at inclusion. RESULTS AND CONCLUSION: The within-group variation for vital signs after injection and 24 hours after was not clinically relevant and no significant difference was evident between treatment groups. The incidence of adverse events was similar in both groups (11.0% for iobitridol and 7.1 % for iohexol), consisting most often of a sensation of warmth. Biologic parameters remained stable and did not differ significantly between groups. The quality of imaging was rated good or excellent in 70% of cases and a very high diagnostic discrimination was achieved (98%). Iobitridol compared favorably with iohexol for head CECT.

Adolescent↗
PubMed1996

[Diagnosis of a post-thrombophlebitic dural fistula using MR angiography].

We report a case in which MRA made it possible to diagnose a dural arteriovenous fistula and thrombophlebitis in a 23-year old woman. 2D TOF MRA is the usual technique in the diagnosis of thrombophlebitis. Our experience shows the limits of 2D TOF since the increased signal intensity in the sinus could simulate a normal flow, and we describe the advantages of MR subtraction angiography. In our study, 3D TOF MRA showed the dural arteriovenous fistula, its location near the right transverse sinus and some of the feeding vessels: tentorial branch of the internal carotid artery and meningeal branch of the right occipital artery. 3D TOF MRA provides the diagnosis of dural arteriovenous fistula, but it cannot replace the plain angiography performed before endovascular or surgical treatment.

Adult↗
PubMed1995

MRI of intramedullary cavernous haemangiomas.

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.

Adult↗
PubMed1995

Auditory cortex activity changes in long-term sensorineural deprivation during crude cochlear electrical stimulation: evaluation by positron emission tomography.

We studied three right-handed human volunteers who have been prelingually deaf for 16 to 26 years. We measured cerebral regional activity (rA) using 15O labelled water and positron emission tomography (PET) during rest and during electrical cochlear stimulation of the right ear. The stimulus consisted of crude constant current squared pulses, it is currently employed in cochlear implant screening. Two subjects described a subjective auditory sensation under cochlear stimulation, the third did not. An increment of the rA (which is linked to the regional cerebral blood flow) in the auditory cortex was observed in all subjects, activation was ipsilateral to stimulation in one subject and contralateral in two subjects. These findings suggest 1) that auditory pathways to the cortex can remain functional a long time after prelinguistic auditory deprivation, 2) that the auditory cortex can be activated by a crude electrical stimulation of the cochlea in the absence of perception of the auditory stimulus, 3) that PET does not seem to offer any advantage for screening patients who have been prelingually deaf for a long time.

Adult↗
PubMed1995

Interictal cerebral metabolism and epilepsy in cavernous angiomas.

We studied glucose metabolism in brain tissue surrounding cavernous angioma in 22 patients, using PET, and evaluated its relation to the size, site and epileptogenic nature of the vascular malformation, as well as to the post-surgical seizure outcome. Preoperatively, 18 patients suffered recurrent seizures, the origin of which could be clearly related to the vascular malformation in 14. Brain metabolism surrounding cavernous angiomas was normal in 18 patients (82%), and significantly decreased in four (18%). In these four patients, but in none of the 18 other cases, the vascular malformation disrupted connections between paralimbic areas and the adjacent temporal neocortex where hypometabolism was most pronounced. The latter did not correlate with the size nor with the epileptogenic nature of the cavernomas. Sixteen epileptic patients underwent surgical removal of their cavernoma, without resection of the surrounding cortex. At 1-year postoperatively, seizures have relapsed in seven patients (44%), including those four whose epilepsy could not be clearly related to the vascular malformation. Conversely, the four patients with perilesional hypometabolism on preoperative PET were seizure free postoperatively. Hypometabolism in brain tissue surrounding cavernomas is a rare finding which seems more likely to reflect deafferentation than the epileptogenic process itself.

Adolescent↗
PubMed1995

Unilateral upper limb asterixis related to primary motor cortex infarction.

BACKGROUND: Unilateral upper limb asterixis related to cortical infarct is an unusual clinical picture. We found this association in two patients. Magnetic resonance imaging (MRI), somatosensory evoked potentials (SEPs), and electromyographic recording were performed. CASE DESCRIPTIONS: Two patients developed an acute upper limb ataxia with asterixis. This consisted of frequent arrhythmic loss of extensor muscle tone on instruction to maintain the wrist and fingers extended. Voluntary electromyographic activity in the left extensor digitorum communis muscle showed abrupt periods of interruption ranging from 90 to 260 milliseconds in duration in the first case and from 60 to 220 milliseconds in the second case. SEPs were normal. MRI disclosed a right cortical infarct within the primary motor cortex in both cases. CONCLUSIONS: These findings indicate that asterixis was not related to a failure in the processing of proprioceptive input controlling the regulation of postural tone of the distal upper limbs because SEPs were normal. The involvement of primary motor cortex might suggest that asterixis results from an impairment of a centrally generated motor-command signal controlling the postural tone of the distal upper limb.

Aged↗