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O Ciccarelli

Publications and source records attributed to O Ciccarelli.

At least 19 recordsLinked to original sources
PubMed2003

From diffusion tractography to quantitative white matter tract measures: a reproducibility study.

The aim of this study is to propose methods for assessing the reproducibility of diffusion tractography algorithms in future clinical studies and to show their application to the tractography algorithm developed in our unit, fast marching tractography (FMT). FMT estimates anatomical connectivity between brain regions using the information provided by diffusion tensor imaging. Three major white-matter pathways were investigated in 11 normal subjects--anterior callosal fibers, optic radiations, and pyramidal tracts. FMT was used to generate maps of connectivity metric, and regions of voxels with highest connectivity metric to an anatomically defined starting point were identified for each tract under investigation. The reproducibilities of tract-"normalized" volume (NV) and fractional anisotropy (FA) measurements were assessed over such regions. The values of tract volumes are consistent with the postmortem data. Coefficients of variation (CVs) for FA and NV ranged from 1.7 to 7.1% and from 2.2 to 18.6%, respectively. CVs were lowest in the anterior callosal fibers (range: 1.7- 7.8%), followed by the optic radiations (range: 1.2-18.6%) and pyramidal tracts (range: 2.6-15.5%), suggesting that fiber organization plays a role in determining the level of FMT reproducibility. In conclusion, these findings underline the importance of assessing the reliability of diffusion tractography before investigating white matter pathology.

Adult↗
PubMed2003

Diffusion tractography based group mapping of major white-matter pathways in the human brain.

Tractography uses diffusion tensor imaging data to trace white matter pathways in vivo within the brain. We have constructed group maps that represent three major white matter tracts-the anterior callosal fibers, optic radiations, and pyramidal tracts-in a group of 21 volunteers. For each individual tract the fast marching tractography (FMT) algorithm was used to generate a VSC (voxel scale connectivity) map in native space. Using SPM99 these maps were transformed into a standard reference frame and three group mapping techniques were investigated: the first averaged the individual VSC maps, the second produced maps that demonstrate intersubject tract variability and degree of overlap, and the third used an SPM analysis to construct a statistical image that represents the group effect. The group maps reconstructed for each tract under investigation conform well to known anatomy and are consistent with data derived from postmortem human brains. Greater intersubject variability is found around the terminal projections of the tracts adjacent to cerebral cortex, whereas the "core" of each tract is characterized by lower variability. No significant differences were found between the left and right side of the pyramidal tracts and optic radiations. The group mapping techniques utilize the VSC maps in different but complementary ways. In the future, group mapping could investigate in vivo white matter differences between normal subjects and patients affected by neurological and psychiatric diseases.

Adult↗
PubMed2003

Non-invasive mapping of connections between human thalamus and cortex using diffusion imaging.

Evidence concerning anatomical connectivities in the human brain is sparse and based largely on limited post-mortem observations. Diffusion tensor imaging has previously been used to define large white-matter tracts in the living human brain, but this technique has had limited success in tracing pathways into gray matter. Here we identified specific connections between human thalamus and cortex using a novel probabilistic tractography algorithm with diffusion imaging data. Classification of thalamic gray matter based on cortical connectivity patterns revealed distinct subregions whose locations correspond to nuclei described previously in histological studies. The connections that we found between thalamus and cortex were similar to those reported for non-human primates and were reproducible between individuals. Our results provide the first quantitative demonstration of reliable inference of anatomical connectivity between human gray matter structures using diffusion data and the first connectivity-based segmentation of gray matter.

Adult↗
PubMed2003

The longitudinal relation between brain lesion load and atrophy in multiple sclerosis: a 14 year follow up study.

BACKGROUND: Studies have suggested that T2 lesion activity is prominent in early relapsing-remitting multiple sclerosis, whereas brain atrophy, while seen early, appears more evident in later progressive disease. The temporal relation between these processes remains unclear. OBJECTIVE: To explore the association between changing brain lesion loads and subsequent tissue atrophy in multiple sclerosis. METHODS: 28 subjects with clinically probable or definite multiple sclerosis (mean age 46.0 years; 17 female and 11 male) were followed for 14 years after first onset of symptoms. T2 lesion loads were estimated soon after symptom onset and at around five, 10, and 14 years later. Disease related atrophy was estimated at the 14 year follow up by comparing brain tissue volumes (proportional to total intracranial volumes) determined in the multiple sclerosis group with data from 29 normal control subjects (mean age 36.7 years; 16 female, 13 male) using multiple linear regression analyses to allow for differences in age and sex distributions. RESULTS: Change in lesion load in the first five years was more closely correlated to disease related brain atrophy at 14 years than later changes in lesion load, although the correlation was only moderate (Spearman correlation = -0.528, p = 0.004). CONCLUSIONS: From this, it appears that early rather than later focal lesion accumulation relates to subsequent brain atrophy, but factors unconnected directly with lesion formation probably also play a significant role in determining such atrophy.

Adult↗
PubMed2001

Investigation of MS normal-appearing brain using diffusion tensor MRI with clinical correlations.

OBJECTIVE: To quantitatively investigate water diffusion changes in normal-appearing white matter (NAWM) and gray matter in patients with MS, and to evaluate whether these changes are correlated with clinical disability and disease duration. BACKGROUND: Diffusion tensor imaging provides quantitative information about the magnitude and directionality (anisotropy) of water diffusion in vivo and detects pathologic changes in MS brain tissue. METHODS: Diffusion tensor imaging was performed in 39 patients with MS and in 21 age-matched control subjects. Quantitative indices, including fractional anisotropy, volume ratio, and mean diffusivity, were obtained in 30 regions of interest located in normal-appearing basal ganglia, cerebellar gray matter, and supratentorial and infratentorial NAWM. RESULTS: Patients with MS showed significantly reduced anisotropy and a trend toward increased diffusivity in the infratentorial and supratentorial NAWM, and significantly increased anisotropy in the basal ganglia. In all patients with MS, both fractional anisotropy and mean diffusivity in the cerebral peduncles were inversely correlated with the Expanded Disability Status Scale and pyramidal functional scores. In patients with relapsing-remitting MS, there was a strong correlation between Expanded Disability Status Scale score and fractional anisotropy in both supratentorial and infratentorial NAWM. In primary and secondary progressive MS, disease duration correlated strongly with mean diffusivity in infratentorial NAWM and fractional anisotropy in the cerebral peduncles, respectively. CONCLUSION: The most striking finding of decreased fractional anisotropy in supratentorial and infratentorial NAWM and increased fractional anisotropy in basal ganglia may result from axonal degeneration due to fiber transection in remote focal lesions. Diffusion tensor imaging indices, in particular fractional anisotropy, appear sensitive to structural damage in NAWM that is associated with disability and progression in MS.

Adult↗
PubMed2001

Adult liver transplantation and steroid-azathioprine withdrawal in cyclosporine (Sandimmun)-based immunosuppression - 5 year results of a prospective study.

New immunosuppressants are said to be superior to cyclosporine due to their higher incidence of steroid sparing and to the reduced incidence of side-effects. From May 1992 to February 1995, 79 adults underwent primary liver transplantation using cyclosporine A (Sandimmun)-based triple drug immunosuppression. Nine patients who died early after liver transplantation due to reasons unrelated to immunological problems were excluded from this analysis. The long-term outcome of the remaining 70 patients was prospectively studied in relation to steroid and azathioprine withdrawal. They were re-evaluated 6-monthly in relation to liver and kidney function; cholesterolemia, infection, de novo diabetes mellitus and arterial hypertension, malignancy, ophthalmological and osteomuscular diseases. In case of rejection occurring during or after steroid tapering, patients were switched, by protocol, to tacrolimus therapy. Median follow-up was 81 months (range 60-96). Forty-four patients (62.8 %) were biopsied 5 years after transplant; 20 patients (28.6 %) were biopsied at a median follow-up of 32 months (range 7.8-47). Six patients (8.6 %) who refused biopsies more than 1 year after liver transplantation had normal liver values throughout the whole follow-up period. Five-year actual patient and graft survivals were 75 % and 65.8 %, respectively, for the whole group (n = 79) and 85.7 % and 74.3 % for the studied group (n = 70). Steroids could be withdrawn in all but two patients (97.1 %) at a median time of 7 months (range 3-42). Steroids were restarted in six patients (8.6 %) for extrahepatic reasons. Freedom from steroids was thus observed in 62 patients (88.6 %). Seven patients (10 %) had rejection after steroid tapering; six were switched to tacrolimus. Two patients (2.9 %) needed retransplantation because of acute and chronic rejection whilst still being on full immunosuppression. In total, three patients (4.3 %) had histological signs of chronic rejection during follow-up. At 5 years post-transplant, 66.6 % and 13.3 % of the 60 patients at risk were on cyclosporine and tacrolimus monotherapy, respectively; 93.3 % were steroid-free. Mean creatinine and cholesterol levels were 1.56 +/- 1.3 mg/dl and 193.5 +/- 56.6 mg/dl; incidences of de novo arterial hypertension, insulin dependent diabetes mellitus were 26.6 % and 13.3 %. Two patients (2.8 %) developed post-transplant lymphoproliferative disease, two (2.8 %) had skin cancer. Cyclosporine-based immunosuppression allows safe steroid withdrawal in most patients and cyclosporine monotherapy can be achieved in two-thirds without compromising graft and patient survival. Results of new immunosuppressive strategies should be approached with caution, especially when considering steroid sparing and the incidence of side-effects.

Adolescent↗
PubMed2001

Hepatic vein obstruction due to hypertrophy of right split-liver adult allograft.

The increasing shortage of liver allografts has led to the development of split liver transplantation. More frequent applications have permitted the resolution of most of its technical complications. A hitherto unreported complication of split liver transplantation, hepatic vein obstruction caused by hypertrophy of a right split-liver adult allograft, is discussed. As surgical correction was impossible, the outflow obstruction was treated successfully with interventional radiology.

Adult↗
PubMed2001

Favorable outcome of orthotopic liver transplantation in a patient with subacute liver failure due to the emergence of a hepatitis B YMDD escape mutant virus.

BACKGROUND/AIMS: Patients with end-stage liver disease due to chronic hepatitis B infection in whom a YMDD escape hepatitis B virus (HBV) mutant has emerged under lamivudine treatment are generally denied liver transplantation (OLT). METHODS: We report the case of a male patient who was started on prophylactic treatment with lamivudine in the context of recurrent episodes of HBV reactivation during high dose immunosuppressive therapy for relapsing severe pulmonary sarcoidosis. RESULTS: Following the emergence of a YMDD escape mutant virus under lamivudine treatment, he developed subacute liver failure requiring liver transplantation. The patient was treated with a combination of intravenous hepatitis B immune globulin (HBIG) which was started perioperatively and also continued lamivudine after OLT. Twelve months after OLT, there was no evidence of HBV reinfection of the liver graft with the use of HBIG and lamivudine. CONCLUSIONS: This observation suggests that emergence of the YMDD mutation is not a contra-indication to OLT, providing adequate immunoprophylaxis using HBIG and lamivudine combination therapy.

Adult↗
PubMed2001

Diffusion tensor imaging in early relapsing-remitting multiple sclerosis.

Diffusion tensor magnetic resonance imaging (DTI) indices are abnormal in patients with established multiple sclerosis (MS). The objective of this study was to examine the diffusion characteristics of MS lesions, normal appearing white matter (NAWM) and normal appearing grey matter (NAGM) in MS patients with early relapsing-remitting disease. A further objective was to investigate the relationship between three DTI parameters (fractional anisotropy (FA), mean diffusivity (MD) and volume ratio (VR)) and clinical outcome measures (Kurtzke expanded disability status scale (EDSS) and MS Functional Composite Measure) in early disease. DTI was performed in 28 patients and 27 controls. Analysis was carried out using a region of interest (ROI) approach. ROIs were placed in 12 NAWM and nine NAGM regions. Significant differences were found in FA, MD and VR between lesions and NAWM (P< 0.001 for all three DTI parameters). No significant differences were found between patients and controls when examining NAWM or NAGM, although there was a trend for abnormal NAWM FA and VR in some regions. No correlation was found between DTI parameters in lesions, NAWM or NAGM and the clinical outcome measures. The lack of significant DTI abnormality in the NAWM and NAGM may reflect a lack of pathological change or a limited sensitivity of DTI using ROI methodology. Previous studies have shown abnormalities in TI relaxation time, magnetisation transfer ratio (MTR) and N-Acetyl aspartate (NM) in this cohort of patients, and as such, DTI using a region of interest (ROI) approach may not be as sensitive as other MR techniques in detecting subtle changes in normal appearing brain

Adult↗
PubMed2000

mtDNA A3243G MELAS mutation is not associated with multigenerational female migraine.

The authors searched for mitochondrial DNA (mtDNA) A3243G mutation in peripheral blood leukocytes from female migraine patients with pure matrilinear history of migraine along two or three generations. The current study was designed to exclude any male transmission of the disease. The mutation was absent in all patients. We conclude that mtDNA A3243G mutation does not contribute to the pathogenesis of pure matrilinear multigenerational migraine with or without aura.

Adult↗
PubMed2000

Antinuclear antibodies and response to IFNbeta-1a therapy in relapsing-remitting multiple sclerosis.

We determined whether positive ANA was related to response to rIFNss-1a in 62 relapsing-remitting MS patients. According to the presence of antinuclear antibodies (ANA) at baseline and during the first 6 months of treatment, patients were sorted in different groups. The clinical and MRI outcome during short-term (6 months) and long-term (24 months) treatment period was not statistically different between the groups. Therefore, the response to IFNbeta-1a seems not to be influenced by ANA occurrence either before or during treatment. When the analysis was extended to other autoantibodies (i. e. antithyroid, anticardiolipin) similar results were obtained.

Adjuvants, Immunologic↗
PubMed2000

Adult liver transplantation: the Université Catholique de Louvain experience.

Liver transplantation remains a formidable surgical and medical procedure. The larger single centre experience confirms that standardization of perioperative care and simplification of the surgical procedure markedly improve results. Further efforts must be made in relation to immunosuppressive therapy in order to minimize late morbidity and mortality.

Adolescent↗
PubMed1999

Hepatic sickling: an unusual cause of liver allograft dysfunction.

Orthotopic liver transplantation can be performed successfully in thalassemia. In this article, we describe a case of liver transplantation in a patient with sickle cell/beta-thalassemia complicated by liver sickling. Intrahepatic sickling must be considered in case of allograft dysfunction. This condition can easily be diagnosed by biochemical investigation and liver ultrasonography.

Adult↗
PubMed1999

Malakoplakia of the caecum in a kidney-transplant recipient: presentation as acute tumoral perforation and fatal outcome.

Malakoplakia is a rare pseudotumoral inflammatory disease known to affect immunocompromised subjects, mainly with a history of recurrent Escherichia coli infection. The urinary tract is the most frequent site of the disease, although all organs can be involved. In the present article, we report a case of malakoplakia of the caecum, that developed in a 52-year-old man, who had received a kidney transplant 9 years before and had a history of recurrent E. coli urinary tract infections. Malakoplakia presented as acute intestinal perforation, and, despite aggressive surgical and medical management, disease progressed toward a fatal outcome due to sepsis and multiple organ failure 9 months later. A defect in the macrophagic activity was demonstrated.

Bacteremia↗
PubMed1999

Magnetic resonance imaging outcome of new enhancing lesions in relapsing-remitting multiple sclerosis patients treated with interferon beta1a.

We investigated whether interferon-beta1a modifies the course of new enhancing lesions in relapsing-remitting multiple sclerosis. Sixty-eight patients were studied by monthly magnetic resonance imaging (MRI) in a pretest-posttest design including 6 months of observation and 6 months of treatment. We examined the course of new Gd-enhancing lesions on two consecutive scans during observation and during treatment. Lesions detected during treatment were also analyzed by MRI 1 year later for persistence of enhancement, persistence of T2 hyperintensity, development of T1 hypointensity, or disappearance. Among the enhancing lesions detected by observation and treatment MRI, respectively, Gd-enhancement persisted at 2 months in 20% and 3% (P < 0.001), T2 hyperintensity persisted in 86% and 63% (P < 0.03), and T1 hypointensity developed in 49% and 15% (P < 0.01). Progression to T1 hypointensity was significantly more frequent in larger lesions during both the observation and treatment periods (P < 0.01). No reenhancement of plaques was present at 1-year follow-up; a further reduction in T2 hyperintensity (63% vs. 39%) was observed while T1 hypointensity remained unchanged. Both the duration of Gd enhancement and the short-term MRI course of new enhancing lesions benefited by treatment with recombinant interferon-beta1a treatment.

Adjuvants, Immunologic↗
PubMed1999

Fatigue and magnetic resonance imaging activity in multiple sclerosis.

Fatigue is a frequent and often severe symptom in multiple sclerosis. Pathogenic mechanisms proposed for fatigue include the release of proinflammatory cytokines, which is thought to have an important effect on changes in the blood-brain barrier (BBB). To investigate whether fatigue is related to BBB disruption we studied 11 relapsing-remitting MS patients participating in a multicenter longitudinal study comparing the sensitivity of monthly enhanced magnetic resonance imaging (MRI) after standard-dose and triple-dose injection of gadolinium-diethylene triaminopentoacetic acid (Gd-DTPA). Serial Gd-enhanced MRI studies were performed in two separate sessions every 4 weeks for 3 months. An expanded version of the Fatigue Severity Scale, including 29 items, was administered 24 h before each MRI examination. No relationship was found between the number and volume of Gd-enhancing lesions and fatigue scores at any monthly examination over the study period. Furthermore changes in MRI activity were not significantly related to changes in fatigue scores. These results were obtained on triple-dose delayed scanning, which is more sensitive than standard-dose scanning in detecting areas of BBB disruption. Our preliminary results thus do not support the hypothesis of a relationship between BBB alterations and fatigue severity in multiple sclerosis.

Adult↗