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Biomedical subjects

A Righini

Publications and source records attributed to A Righini.

27 records · Page 2Linked to original sources
PubMedDate not supplied

Curved CT reformatted images of head scans.

Attempts have been made to overcome the limited visibility of anatomic structures on axial CT by direct multiplanar sections or multiplanar reformatted views. So as not to be restricted by "planar cuts," we have used curved coronal reformatting to investigate some of the cranial structures, whose tortuous anatomy cannot be visualized entirely with standard CT. In fact, we have provided a "flattened" presentation of the optic nerve and chiasma, facial nerve canal, and jugular foramen, showing them in their entire extension. Despite the geometrical deformation produced by this technique, its potential to depict the anatomy of some structures is noteworthy.

Glomus Tumor↗
PubMedDate not supplied

Functional MRI: primary motor cortex localization in patients with brain tumors.

PURPOSE: Our goal was (a) to test the ability of functional MRI (fMRI) to localize the hand primary motor cortex in patients with brain neoplasms using a conventional scanner and (b) to compare within the same subject the location and morphology of the activated motor areas in the affected hemisphere with the contralateral ones. METHOD: Seventeen right-handed patients with frontoparietal intra- and extraaxial tumors were studied. Hand motor performance ranged from normal to slight impairment of finger dexterity. The fMRI study was based on a series of FLASH images. Two or three contiguous slices parallel to the bicommissural plane were acquired through the level of frontoparietal cortex. Each patient was requested to perform with each hand a finger-tapping task or a simpler repetitive flexion-extension of the last four fingers. Pseudo-color activation maps were then calculated by a Z-score method and superimposed on high resolution images. RESULTS: Five patients were excluded because of gross motion artifacts. In all other patients, areas of significant signal increase were detected on the precentral gyrus. They had a spot-like appearance, and no substantial side-to-side differences in shape or extension could be observed. In the presence of severe compression of the gyri, a displacement of the activated areas in the affected hemisphere with respect to the contralateral ones was noticeable. CONCLUSION: fMRI localization of the primary motor area using a conventional scanner can be obtained also in patients with brain tumors, although with a lower success rate than in normal volunteer studies, mainly because of subject compliance problems. Areas of significantly increased signal are detectable even in cortex where normal anatomical patterns are lost.

Adolescent↗
PubMedDate not supplied

fMRI changes in the brain associated with the carotid compression test.

PURPOSE: The purpose of our investigation was to study in normal volunteers the response to a unilateral common carotid (CC) compression test using dynamic MRI sensitive to variations in blood magnetic susceptibility. METHOD: Nine volunteers, positioned in a 1.5 T MR scanner, performed a unilateral 40 to 45 s CC self-compression during the acquisition of single slice axial T2*-weighted FLASH images. RESULTS: In three subjects, the signal showed a significant 2% drop from baseline in the ipsilateral frontal temporal cortex during the compression. In another three subjects, a significant 1.5-2% signal decrease was observed in both hemispheres. In two subjects whose MR angiography showed abnormalities of the circle of Willis, the bilateral signal drop was more remarkable (3%). In one volunteer, the signal did not change. CONCLUSION: Increased deoxyhemoglobin within the brain microcirculation is the probable explanation for the signal drop. This method could be further tested in view of the widespread use of open interventional MR units.

Adult↗
PubMedDate not supplied

Facial asymmetry in partial epilepsies.

Fifty-six consecutive epileptic patients with partial seizures (30 temporal, 26 extratemporal) and facial asymmetry were studied. Facial asymmetry was compared with EEG, radiologic, and other clinical findings. Thirty patients had a lesional epilepsy whereas 26 were considered cryptogenic. In lesional epilepsies, 60% of patients had EEG foci ipsilateral to the smaller hemiface and only 20% had EEG foci contralaterally. In the cryptogenic group, the EEG focus was ipsilateral in 50% and contralateral to the facial smallness in 46%. No differences were noted between temporal and extratemporal epilepsies. Early acquired cerebral lesions may modify development of the hemisphere involved, leading to a small ipsilateral hemiface and seizures originating from the same side.

Adult↗
PubMedDate not supplied

Hippocampal infolding angle changes during brain development assessed by prenatal MR imaging.

BACKGROUND AND PURPOSE: Epileptic syndromes or neurodevelopmental delay may be associated with congenital anomalies of the shape or the orientation of the hippocampus. Scarce data are available about quantitative hippocampal developmental changes during fetal life, in particular about the progressive rotational changes of the hippocampal infolding angle (HIA), which can be considered a hallmark of hippocampal development. We hypothesized that prenatal MR imaging could demonstrate the progressive rotation of the hippocampus, providing quantitative data by means of the HIA determination. METHODS: We retrospectively selected 62 fetal MR imaging cases with normal brain at prenatal and postnatal imaging. The gestational age ranged from 20 to 37 weeks. The coronal section encompassing the pons was used to perform the measurement of HIA. HIA was defined as the angle between the line connecting the lateral margin of the cornu ammonis with the medial superior margin of the subiculum and the line passing through the midline structures. RESULTS: A significant positive correlation was found between the HIA value and the gestational age. The HIA was generally below 70 degrees before the gestational week 25 and above 70 degrees after week 30. CONCLUSION: Prenatal MR imaging allowed the progressive rotation of hippocampus to be detected during fetal life, providing normative data about HIA changes. These data could support further investigations to assess how fetal HIA anomalies might affect postnatal neurologic outcome.

Female↗
PubMedDate not supplied

MR of diffusion slowing in global cerebral ischemia.

PURPOSE: To investigate the causal connections between ischemia and the hyperintensity in diffusion-weighted MR images that has been associated with it. METHODS: Diffusion-weighted and T2-weighted MR imaging were used in a feline global cerebral ischemia/reperfusion model. Single 30-minute vascular occlusions followed by reperfusion were studied. Global occlusions were used to avoid interpretive complications associated with the temporally unstable hemodynamics of the penumbral zones around focal occlusions and the possible growth of the ischemic and penumbral regions with time. RESULTS: Diffusion-weighted hyperintensity and the associated diffusional slowing were not attributable exclusively to the cessation of blood flow because: 1) it does not appear abruptly at the onset of ischemia; 2) it resolves slowly early in reperfusion; and 3) it reappears after prolonged reperfusion. CONCLUSION: The times during which diffusion-weighted hyperintensity is manifested during ischemia, and recovers with reperfusion, point to a role for energy metabolism failure.

Animals↗