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Biomedical subjects

A Righini

Publications and source records attributed to A Righini.

At least 19 recordsLinked to original sources
PubMed2006

Spinal cord and vertebral stroke: a paediatric case.

Spinal cord ischaemia is a rare entity and very few cases of simultaneous spinal cord and vertebral body infarction have been reported: all of them in adult age. We observed a 15-year-old girl with abrupt onset of myelopathy and pain at the vertebral column studied by means of serial magnetic resonance imaging (MRI), and in whom bone infarction was a confirmatory sign of the vascular origin of the spinal lesion. This is to the best of our knowledge the first paediatric case described in the literature.

Adolescent↗
PubMed2005

Parkinson's disease, chronic hydrocarbon exposure and striatal neuronal damage: a 1-H MRS study.

Several patients with Parkinson' s disease (PD) reveal an history of chronic exposure to hydrocarbon-solvents. Chronic exposure to hydrocarbon-solvents has been proposed as a risk factor for more severe forms of PD with earlier onset of symptoms and reduced response to dopaminergic therapy. A direct correlation between disease severity and exposure degree has been previously shown. Seven exposed PD patients (two with low degree exposure and five with high degree exposure), 10 unexposed PD patients matched for sex, age and Hoehn and Yahr scale (=3 in the "on" phase), and 10 unexposed PD patients matched for sex, age and l-dopa daily intake instead of disease severity (Hoehn and Yahr scale=3.5 in the "on" phase) were studied. Twenty normal subjects without previous exposure to hydrocarbon-solvents and matched for age and sex with HPD patients were studied for comparison. The purpose of the study was to assess neuronal degeneration in the striatum of exposed vs unexposed PD patients. The authors investigated whether neuronal damage/loss was detectable in the lentiform nucleus measuring N-acetylaspartate (NAA) levels by 1-H MRS. Multiple single voxel MRS water-suppressed spectra were obtained also from the white matter and the occipital lobe. NAA was normal in the lentiform nucleus of patients with low exposure as well as in patients with no exposure whereas it was decreased in PD patients with high degree exposure. White matter and occipital lobe NAA content was normal both in exposed and unexposed PD patients. Clinical expression is more severe in PD patients with previous high degree solvent exposure because of the associated post-synaptic damage of the nigro-striatal pathway.

Aged↗
PubMed2005

Thrombophilia and fetal germinal matrix-intraventricular hemorrhage: does it matter?

Germinal matrix-intraventricular hemorrhage (GMH-IVH) in the fetus is very rare and the role of thrombophilia in its pathogenesis is unclear. We report on the prenatal diagnosis by magnetic resonance imaging of GMH-IVH in a 24-week fetus. The newborn presented posthemorrhagic ventriculomegaly and was found to be heterozygous for two thrombophilic patterns, factor V Leiden and methylenetetrahydrofolate reductase mutation. The combination of this hypercoagulable state and prenatal GMH-IVH is discussed together with the opportunity of testing these infants for thrombophilia.

Adult↗
PubMed2004

The role of integrated imaging techniques for prenatal prediction of phenotype in two cases of facial anomalies.

OBJECTIVES: Fetal face malformations represent one of the most challenging prenatal diagnoses mainly because of the wide range of morphological features involved. We tested an approach based on a combination of conventional two-dimensional ultrasound with the more recent three-dimensional technique plus magnetic resonance imaging, in order to improve parents' understanding of fetal face anomalies, thereby facilitating parent counselling. METHODS: Two cases of fetal facial anomaly were studied using these combined techniques; one had severe micrognathia and malformation of the ears with preauricular tags, while the other had bilateral dacryocystocele and severe hypertelorism. RESULTS: The images generated by three-dimensional ultrasound enabled the parents to visualize their child immediately and helped them to adjust to the diagnosis of facial defects and its clinical consequences. CONCLUSIONS: An approach based on combined use of different imaging techniques was found useful in both cases.

Adult↗
PubMed2002

Cerebellar mature teratoma in adulthood.

Mature teratoma of the posterior cranial fossa in adults is extremely rare. We report a particularly rare case of medio-lateral cerebellar mature teratoma that became symptomatic in a middle-aged man. The CT revealed the lesion of heterogeneous density with calcifications in the solid medial portion. Only the MRI could reliably define the borders of the cystic component extending into the left cerebellar lobe. Histologically the presence of fully matured representative tissues of the 3 germ layers ensured the diagnosis of mature teratoma. We suggest that the cyst formation from progressive latent hemorrhage and/or secretion from the gland cells of the tumor, may be responsible for the clinical decompensation even in adulthood.

Cerebellar Neoplasms↗
PubMed2000

Hydrocarbon exposure and Parkinson's disease.

BACKGROUND: Single cases of parkinsonism have been associated with hydrocarbon solvents. OBJECTIVE: To determine whether exposure to hydrocarbon solvents is related to PD. METHODS: Cohort study of 990 patients with PD according to Core Assessment Program for Intracerebral Transplantations (CAPIT) criteria, selected from 1455 consecutive subjects presenting at a referral center; case-control study assessing Unified PD Rating Scale scores (motor score as primary endpoint) in all subjects with positive history of hydrocarbon solvent exposure (n = 188), matched for duration of disease and gender to 188 subjects selected from the remaining 802 with a negative history. Two subgroups in the case-control study included the following: 1) response to apomorphine (n = 26); 2) brain MRI (n = 15). PET imaging (n = 9) was compared with that of historic controls. RESULTS: Exposed patients were younger (61.0 +/- 9.4 versus 64.7 +/- 9.4 years, p = 0.002), predominantly male (76.4% versus 45.2%, p = 0.0001), less educated (8.4 +/- 4.2 versus 10.1 +/- 4.4 years, p = 0.0001), and younger at onset of disease (55.2 +/- 9.8 versus 58.6 +/- 10 years, p = 0.014). Exposure to hydrocarbon solvents directly correlated to disease severity (r = 0. 311) and inversely correlated to latency period (r = -0.252). Nine blue-collar occupations accounted for 91.1% of exposures. CONCLUSIONS: Occupations involving the use of hydrocarbon solvents are a risk factor for earlier onset of symptoms of PD and more severe disease throughout its course. Hydrocarbon solvents may be involved in the etiopathogenesis of PD, which does not have a major genetic component.

Adult↗
PubMed1999

T1 and T2 in the brain of healthy subjects, patients with Parkinson disease, and patients with multiple system atrophy: relation to iron content.

PURPOSE: To investigate the potential of magnetic resonance imaging for identification and quantification of brain iron in healthy subjects, patients with Parkinson disease, and patients with multiple system atrophy. MATERIALS AND METHODS: Forty-nine subjects were studied at 1.5 T. Regional T1 and T2 values were compared among groups and also with histopathologic estimates of iron concentration. RESULTS: In healthy subjects, interregional T1 and T2 differences in the cortex and basal ganglia showed a good correlation with reported values for iron concentration, and intraregional variations were generally consistent with reported variability of iron concentration. Patients with multiple system atrophy had T1 and T2 shortening in the globus pallidus consistent with reported increases in ferritin-bound iron and changes in the putamen consistent with accumulation of hemosiderin (posterior portion) and neuromelanin (remainder). Both groups of patients had changes in the cortex that are consistent with decreased ferritin concentration and T2 changes in white matter consistent with demyelination. Patients with Parkinson disease also had a (nonsignificant) T2 shortening in the substantia nigra that was suggestive of iron accumulation. CONCLUSION: Most of the T1 and T2 findings appear to be related to changes in iron content and form and may possibly be used as indicators of such changes.

Aged↗
PubMed1999

Percutaneous treatment of gas-containing lumbar disc herniation. Report of two cases.

A limited number of cases have been reported in which gas-containing lumbar disc herniation caused compression of nerve roots. The authors describe two patients in whom computerized tomography scanning revealed a large intraspinal gas collection that appeared to be causing nerve root compression and that was successfully evacuated by percutaneous needle aspiration.

Aged↗
PubMed1996

Imaging focal reperfusion injury following global ischemia with diffusion-weighted magnetic resonance imaging and 1H-magnetic resonance spectroscopy.

The purpose of the study was to determine whether diffusion-weighted magnetic resonance imaging (DWI) could identify focal lesions that develop in ischemia-sensitive cerebral tissues during reperfusion following global brain ischemia. Localized 1H-Magnetic Resonance Spectroscopy (1H-MRS) measurements were also obtained to determine whether abnormal spectroscopic markers were associated with focal lesions and to define time correlations between DWI and metabolic changes. Brain diffusion-weighted magnetic resonance imaging measurements were made in a cat model of repetitive global cerebral ischemia and reperfusion. Five animals were exposed to three episodes of 10 min vascular occlusions at hourly intervals. Three animals were evaluated as controls. DWI, T2WI, and 1H-MRS data were acquired for up to 12 h. Transient focal DWI hyperintensity was detected in the hippocampus, basal ganglia, and cortical watershed areas. These focal abnormalities usually appeared during the final reperfusion and eventually spread to encompass all of the gray matter. Spectroscopic measurements demonstrated the expected elevation of the lactate signal intensity during vessel occlusion, which returned to normal during early reperfusion. A subsequent rise in the lactate signal occurred approximately 3-4 h after the beginning of the third reperfusion. This late lactate elevation occurred after focal hyperintensities were identified by DWI. No significant signal changes were seen in spectroscopic metabolites other than lactate. The study illustrates that DWI and 1H-MRS are sensitive to focal cerebral lesions that occur during reperfusion following global cerebral ischemia.

Animals↗
PubMed1996

High temporal resolution diffusion MRI of global cerebral ischemia and reperfusion.

Although brain ischemia has been extensively studied using diffusion-weighted magnetic resonance imaging, most studies performed so far have not had adequate time resolution to follow the temporal changes in the water apparent diffusion coefficient (ADC) in hyperacute ischemia. Using diffusion echo planar imaging, we obtained ADC maps (calculated from measurements made with 8 b-values) with a time resolution of 43 s in a feline model of global brain ischemia and reperfusion. Different protocols were performed: 10-min hypoperfusion, 10- and 22-min ischemia followed by reperfusion, and cardiac arrest. ADC values were obtained from white matter of the internal capsule and from the thalamus. Cortical gray matter measurements were not deemed reliable due to the close proximity of CSF in the cortical sulci. Following occlusion, the ADC declined in the thalamus to < 2 SD of its normal baseline value within 1.5-2.5 min. This decay was exponential with a time constant (tau +/- SD) of 6.0 +/- 2.6 min; no further decrease in the ADC was observed 10 min following ischemia. Following reperfusion, in animals that showed ADC recovery, the ADC began increasing immediately, returning to its preischemic value in approximately 15 min. No significant ADC changes were observed during hypoperfusion. Following cardiac arrest, the decay of ADC was more rapid in the thalamus (tau = 2.6 +/- 0.6 min) than in white matter (tau = 6.6 +/- 1.8 min). We observed that the ADC at 40 min after cardiac arrest was similar to the ADC at 10 min after ischemia. Given that all animals subjected to 10-min ischemic episodes showed ADC recovery with reperfusion, doubt is cast on whether it is possible to define a threshold value of the ADC below which brain tissue is irreversibly damaged. Finally, despite variability in the time constants of the ADC decay induced by ischemia, the ADC values at 10 min were very similar in all the animals. This suggests that when blood flow is diminished sufficiently to induce an ADC reduction, differences in perfusion affect the rapidity of the decrease but not the final asymptotic value reached.

Animals↗
PubMed1995

Cerebral white matter in the centrum semiovale exhibits a larger N-acetyl signal than does gray matter in long echo time 1H-magnetic resonance spectroscopic imaging.

Long echo time (272 ms) 1H magnetic resonance spectroscopic imaging was used to measure the relative magnitudes of the N-acetylaspartate (NAA) signal in a variety of anatomically defined brain structures (centrum semiovale, thalamus, medial frontal cortex, and genu of the corpus callosum) composed primarily of gray matter or white matter. Six normal young adult humans aged 30-40 were studied. With a 95% level of statistical confidence, the white matter in the centrum semiovale (CSO) produced a more intense NAA signal than did the gray matter in the thalamus and the frontal cortex. Differences between the white matter regions were also noted. The CSO white matter's NAA signal yielded a larger NAA signal than did the white matter of the genu of the corpus callosum. Possible reasons for the anatomical variation in the cerebral NAA signal intensity are discussed.

Adult↗
PubMed1995

Blue blood or black blood: R1 effects in gradient-echo echo-planar functional neuroimaging.

Changes in the longitudinal relaxation rate (R1) may play a role in the MRI signal intensity increases that have been associated with physiological brain activation. We used gradient-echo echo-planar MRI (GRE-EPI) to test whether physiological activations associated with hypercapnia in dogs were dependent on the delay (TR) between successive images in a time-series. Our results show that, in addition to activation-induced changes in the R2 (transverse relaxation including inhomogeneity effects), activation-induced changes in R1 are significant under certain pulsing conditions. In our paradigm, the R1 contribution became significant at TR values of 1 s or less.

Animals↗
PubMed1995

Brain regional distribution pattern of metabolite signal intensities in young adults by proton magnetic resonance spectroscopic imaging.

Proton magnetic resonance spectroscopy (1H-MRS) is evolving from single-volume localized acquisitions to multiple-volume acquisitions using magnetic resonance spectroscopic imaging (1H-MRSI). The normal regional patterns of 1H-MRSI-detectable metabolite signal intensities have yet to be established. We studied 13 healthy young adults with a multiple-section 1H-MRSI technique. The metabolite signals measured were N-acetylaspartate (NA), choline-containing compounds (CHO), creatine-phosphocreatine (CRE), and lactate. Ten neuroanatomic regions (nine bilateral) were identified in gray matter, white matter, and basal nuclei. Analysis of the data led to the following conclusions: (1) NA and CHO signals from centrum semiovale (CSO) can be used as a normalizing factor to reduce intersubject variability due to external causes; (2) in normal human brain, there is no left versus right asymmetry in the regions studied; (3) statistically significant patterns of signal distribution of NA, CHO, and CRE can be identified in normal human brain; and (4) CSO-normalized metabolite signal intensities and metabolite ratios complement each other for the detection of significant regional differences.

Adult↗
PubMed1994

Interobserver variability in CT assessment of brain atrophy.

To assess interobserver variability in estimation of brain atrophy based on CT, four neuroradiologists examined CT brain images of 150 consecutive patients without focal lesions. An independent neuroradiologist made the following quantitative measurements: frontal horn index, subarachnoid space area and the ratio between subarachnoid space area and inner skull space area. Level of agreement was fair for the presence (k = 0.24), slight for the degree (mild, moderate, severe) (k = 0.24) and moderate for the type (cortical, subcortical, mixed) of atrophy (k = 0.59). There was a highly significant correlation between the number of observers agreeing and quantitative measurements. We concluded that neuroradiologists' subjective estimation of brain atrophy alone is not reliable. Quantitative measurements would be needed in cases where the presence of brain atrophy might determine clinical decisions.

Adult↗
PubMed1994

Brain parenchyma apparent diffusion coefficient alterations associated with experimental complex partial status epilepticus.

The objective of this study was to evaluate whether water apparent diffusion coefficient (ADC) measurements provide more specific information than T2-weighted MRI about the evolution of brain parenchyma lesions secondary to prolonged complex partial seizures. We measured the ADC in the brain of rats exhibiting prolonged complex partial seizures induced by intraperitoneal injection of kainic acid (KA). The animals were imaged with diffusion and T2-weighted MRI at 2 T from 3 h up to 9 days after KA injection. In the piriform cortex and amygdala, the T2-weighted MRI signal intensity appeared to be uniformly increased from 24 to 72 h after KA injection, and returned to normal by 9 days. In the same regions between 24 and 72 h, the ADC first decreased and then increased. The ADC changes were consistent with the known histopathologic alterations. In this complex partial seizure model, the ADC measurement provides more specific information than T2-weighted MRI about the histopathologic evolution of the lesions. This supports the proposal that diffusion MRI may be valuable for the evaluation of the neuropathologic sequelae in patients with multiple or prolonged seizures.

Animals↗
PubMed1993

Histopathologic correlates of abnormal water diffusion in cerebral ischemia: diffusion-weighted MR imaging and light and electron microscopic study.

PURPOSE: To correlate the findings on diffusion-weighted magnetic resonance (MR) images with the cytologic and histologic findings in ischemic tissue. MATERIALS AND METHODS: A photochemical model of cerebral infarction in rats was studied with diffusion- and T2-weighted MR imaging. The development of lesions was followed from 20 minutes to 5 days after the onset of ischemia. Apparent water diffusion coefficient (ADC) maps were calculated and correlated with light and electron microscopic findings. RESULTS: T2-weighted images clearly showed vasogenic edema but did not enable distinction between areas with cellular damage and the surrounding edematous regions. In contrast, the ADC, which was elevated in nonischemic edematous regions, was diminished in areas with histologic evidence of ischemic damage or necrosis. In the core of the infarct, the ADC became elevated when electron microscopy revealed cellular lysis. CONCLUSION: Diffusion-weighted images may help ascertain the extent of cellular damage and death after stroke.

Animals↗