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Neuroimaging - Basic neurophysiology
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GUIDED POSTER SESSIONS
PS-O3.O41 Neuroimaging Basic neurophysiology -
Brain SPECT scintigraphy in diagnosis of the surrounding oedema after and post anti oedema therapy.
Paediatric stroke: The identification of at-risk tissue using MR diffusion and perfusion imaging. F. Calamant,I F.J.Kirkhamt V. Ganesan~ M. BynevelC- D.G. Gadiant T.C.
P.Predic. Hospital Celje, Slovenia. To precisely diagnose the brain surrounding oedema is very difficult. The study included 56 pts with brain tumor with surrounding oedema and 52 pts post oedema therapy. All pts were simultaneously subjected SPECT scintigraphy with Tc-99m MIBI as a specific tumor marker and Tc-99m ECD as brain surrounding oedema marker. In 56pts with brain tumor and surrounding oedema, the SPECT scintigraphy with Tc-99m MIBi detected the tumor region,while the SPECT with Tc-99m ECD detected greater area of oedema. In 52 pts post oedema therapy on the SPECT with Tc-99m ECD detected non area of oedema. Conclusion: SPECT scintigraphy of brain with Tc-99m MIBi and Tc-99m ECD is a method for detection of brain oedema and enables follow-up of antioedematous therapy.
Use of the navigation system "Stealth Station®" in spine surgery as a support to the transpedicular instrumentation: a preliminary report. E.M. D~a~'t. Camino a Santa Teresa, Mexico City Mexico. OBJECTIVES: To explore the possibilities and limitations of the navigation system "Stealth Station ®" during spine instrumentation in diseases that require placing of transpedieular screws and to evaluate its practical utility. METHOD: In Mexico City, D. F. at Hospital ,~ngeles del Pedregal, from July 1999 to January 2000, we reviewed retrospectively, descriptively and observationally a group of patients who required surgical management for lumbar spinal pathology, and with whom transpedicular instrumentation using the navigation system was used. Patients had to have a CT with a special protocol to diminish the distance between images so that the machine could make the tri-dimensional reconstruction more precisely. Included were patients undergoing neurosurgery and orthopedics. In the period the system was used with 25 patients with lumbosacral instrumentations. It was necessary to elongate the surgical period for an average of 35 to 40 minutes, although and there were no lesions during the procedure; the main mistakes were associated with misuse of the equipment. In this experimental phase use of fluoroscopy to verify the lateral position was agreed upon. RESULTS: Use of the equipment allowed a better tri-dimensional visualization of the vertebrae where the screw had to be placed. The equipment has accessible software that requires training for use. At present use takes time, which elongates surgical times but with further practice use times can be reduced from 15 to 20 minutes. Currently it is a very expensive resource but introduction of its virtual procedures are suggested for orthopedic applications, such as: Preoperative surgical planning, virtual procedure simulations, and use of robots to carry out hip and knee arthroplasty. CONCLUSIONS: Use of spine navigation allows the surgeon to virtually visualize anatomic conditions in a way that is not possible in conventional surgery, giving greater assurance in screw placement. When the surgeon becomes accustomed to the use of this device, fluoroscopy (radiation) is no longer required, but a learning period is required to use it correctly. It is very useful in reviewing surgeries as well as in cervical procedures which have a high risk of damaging delicate anatomic structures.
Cox,, A. Counelly t. Institute of Child Health University College London and Great Ormond St Hospital for Children London UK. Two magnetic resonance imaging (MRI) techniques, diffusion and perfusion imaging, are being used increasingly in the evaluation of the pathopysiology ofstroke(J.Cereb.Blood Flow Metab. 1998, 18:583; J.Cereb.BIood Flow Metab. 1999, 19:701 ). Diffusion M RI provides a measure of the molecular mobility of water in tissue, and early evidence of decreased diffusion is believed to be associated with the development of cytotoxic oedema which occurs as a consequence of impaired energy metabolism and loss of ion homeostasis. Perfusion MRI measures the rate at which blood is delivered to tissue and therefore represents a fundamental parameter in the evaluation of stroke. The combined use of diffusion and perfusion imaging can allow the identification of abnormalities not detected by conventional MRI techniques• and mismatches in regional abnormalities are likely to represent tissue at risk of inlhrction. This work describes our results on the use of diffusion and perfusion MRI for the investigation of tissue at risk in ischaemia in children, including 48 children with sickle cell disease. In this subgroup of patients• abnormalities on perfusion were observed in 25 cases, 9 of which had an abnormality larger than the area of infarction• and 9 had a perfusion deficit in an arterial distribution with no other MRI abnormality (conventional MRI and diffusion MRI). Some of these abnormalities have been shown to be reversible. These areas of mismatch between diffusion and perfusion abnormalities are believed to be at risk of infarction: the supply of oxygen and nutrients to the tissue is compromised, but there is still enough energy to maintain the ionic homeostasis. These MRI techniques should play an important role in investigation of children with stroke, in particular in the management of patients at high risk of stroke, such as those with sickle cell disease and moyamoya disease. Furthermore, they can contribute to the understanding of stroke and the evaluation of new therapeutic strategies.
Contact pressure distribution in supine position in low birth weight infants analyzed by photoelastic method. M. Fuiimatsu, ~hT. Fujita, ' K. Hashimoto, ~H. Nakagawa,~. "Department of Pediatrics, Nippon Medical School Second Hospital, Department of Pediatrics, Omiya Red Cross Hospital, ' Nichinan Galawn, Japan. Background: Contact pressure distribution patterns at supine position of low birth weight (LBW) neonates, were analyzed by photoelastic method. Methods: Total 61 subjects (LBW neonates, matured neonates, normal infants and Down syndrome(DS) infants) were selected. Infants were placed on a photoelastic measuring table. Photoelastic images generated in the contact regions of the body were photographed with a camera and printed on monochrome paper. The coefficient of variation in the pressure distribution Pcv value and the top and bottom ratiol~ of the trunk at the center of pressure were calculated. Results: Pcv value was significantly lower in DS than in LBW (p<0.001), matured (p<0.002), and normal infant s (p<0.01). I~ value in LBW and matured neonates were at 48.9% and 50.2%, respectively. Normal infants at 44.0% were significantly lower than in LBW neonates. However, there was no difference between LBW, and DS infants. Conclusions: Neurological impairment specifically affects the data obtained by photoelastic analysis.
Neuroimagiug - Basic neurophysiology
Value of functional magnetic resonance imaging in memory assessment in epileptic refractory patients. V.H.Machado, J.C.Da Costa, F.Santos, A. Dallacorte, C.M.Neves. PUC-RS. Porto Alegre. Rio Grande do Sul. Brazil. The intracarotid amobarbital testing (IAT) is the current gold standard method to assess language and memory lateralization in epileptic patients under assessment for epilepsy surgery, but it carries potential side effects. The Functional Magnetic Resonance Imaging (tMRI) is an potential alternative method. Our work was to compare the cerebral zones actived by memory paradigms during fMRI with the side of memory in people with epilepsy who have done IAT. Until now, we analysed the results of five patients with epilspsy. The intracarotid amobarbital testing results showed that four patients had memory predominance on the left side. When submitted to fMRI, of the first four patients who had right predominance, three of them had memory predominance on the right side also. One patient had memory predominance on the left side. The patient who had memory predominance on the left side at IAT showed memory predominance on the left side also at fMRI. These preliminary results indicate that fMRI should be an alternative method to assess memory lateralization in patients with epilipsy under assessment for epilepsy surgery, with good sensibility and specificity. Bibliography: 1) Delre J. Functional MRI lateralization of memory in temporal lobe epilepsy. Neurology 1998;50:926-932.
Functional significance of language lateralization. A. Flrel. B. Driiger, J. Sommer, C. Breitenstein, H. Heuningsen, S. Knecht Neurological University Hospital Miinster, Germany. There is limited knowledge about how brain activation during functional imaging relates to brain deactivation from lesions. We therefore compared regional cerebral perfusion increases during a language task to language performance following regional neural inhibition. Healthy individuals with predominantly left (n=7), bilateral (n=6) and right (n=7) language representation were selected from a cohort of 324 subjects in whom lateralization of language related blood perfusion increases had been determined (Brain, 1999, 122:2033-46; Brain, 2000, 123:74-81). Unihemispheric impairment of neural functioning was then elicited by transcranial magnetic stimulation (TMS) of 1Hz at 110% of motor threshold over 10 minutes. TMS has previously been shown to modulate linguistic processing when delivered over ti'ontal or parietal areas of the dominant hemisphere (J Clin Neurophysiol, 1998, 15:325-32; Neuropsychologia, 1999, 37:207-17). Inhibitory TMS of the language dominant hemisphere significantly impaired verbal processing (as measured by verbal reaction times during picture-word-matching) in subjects with unilateral (left or right) language representation. In subjects with bilateral language representation TMS of either hemisphere did not impair language function.
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The present study demonstrates the clinical significance of the variable language lateralization as determined by functional imaging. Language lateralization occurs along a continuum from strong left- to strong rightdominance. Therefore, the behavioral effects of neural inhibition in the sample groups with lelt-, bilateral and right-hemispheric language representation are also best viewed as part of a continuous spectrum of functional susceptibility. The side and the degree of language lateralization will therefore play an important role in determining the extent to which a patient will be affected by a language impairment after a unihemispheric lesion.
Brain a c t i v a t i o n d u r i n g s i m p l e h a n d - f i n g e r s movements vs hand writing; a functional magnetic resonance imaging study. E Pauri~, C. Del Gratta2, A. Ferretti'-, G.L. Romani 2, EM. Rossini *,3. 1: ,4faR, Ospedale Fatebenefratelli Isola T~berina, Roma, 2:ITAB. Universitdt di ChietL 3:Universith Campus Biomedico, Roma - Italy. Handwriting is a highly sophisticated cerebral function which requires a highly integrated brain-hand activity. Few investigations of this have been done using functional brain imaging methodologies. This study aimed to use fMR1 to analyze in detail the pattern of brain activation when the healthy subject is pertbrming a hand-finger movement task or is writing with a pen. Both tasks were compared when using both the dominant and the non-dominant hand. Six healthy volunteers participated in this study after informed consent had been given and the protocol had received the approval of the local Ethics Committee. All of them were right handed according to the Edinburgh Inventory. They were instructed to pertbrm two different motor tasks: a selfpaced finger tapping task, and a writing exercise. The latter consisted of writing the letter 'T' with a pen several times without interruption and without visual feedback. To detect areas of increased MR signal intensity due to the motor tasks, fMR! was performed during a rest condition and during each of the two motor tasks. Activation due to finger tapping and the writing task were statistically compared for each hand separately. The finger movements performed with the right hand induced activation of the primary motor (M 1) and sensorimotor (S 1) area; the same task pertbrmed with the left hand showed a mean activation only of the M I, even though the activated volume was higher. Writing with the right hand provoked activation of the same areas as did right finger tapping, but the Mt volume was about two and a half times larger. The M I volume activated by left-handed writing was three times larger than the finger tapping performed with the same hand, whereas the Talairach co-ordinates indicated that the localisation was the same. The supplementary motor area (SMA) was activated by both right and left hand at the same position: on the left close to the median line. Inferior parietal regions were predominantly activated by left hand writing. The cerebellum was preferentially activated by tasks performed with the left, probably because more attention is devoted to the task when the non-dominant hand is involved. The mean difference between the two motor tasks seems to be the significantly larger activation of M 1 and involvement of the parietal region luting writing. The other major finding was the involvement of the left (dominant) cerebral hemisphere in both tasks, whether performed with the right ~r the left hand.
GUIDED POSTER SESSIONS
PS-O3.O41 Neuroimaging Basic neurophysiology -
Brain SPECT scintigraphy in diagnosis of the surrounding oedema after and post anti oedema therapy.
Paediatric stroke: The identification of at-risk tissue using MR diffusion and perfusion imaging. F. Calamant,I F.J.Kirkhamt V. Ganesan~ M. BynevelC- D.G. Gadiant T.C.
P.Predic. Hospital Celje, Slovenia. To precisely diagnose the brain surrounding oedema is very difficult. The study included 56 pts with brain tumor with surrounding oedema and 52 pts post oedema therapy. All pts were simultaneously subjected SPECT scintigraphy with Tc-99m MIBI as a specific tumor marker and Tc-99m ECD as brain surrounding oedema marker. In 56pts with brain tumor and surrounding oedema, the SPECT scintigraphy with Tc-99m MIBi detected the tumor region,while the SPECT with Tc-99m ECD detected greater area of oedema. In 52 pts post oedema therapy on the SPECT with Tc-99m ECD detected non area of oedema. Conclusion: SPECT scintigraphy of brain with Tc-99m MIBi and Tc-99m ECD is a method for detection of brain oedema and enables follow-up of antioedematous therapy.
Use of the navigation system "Stealth Station®" in spine surgery as a support to the transpedicular instrumentation: a preliminary report. E.M. D~a~'t. Camino a Santa Teresa, Mexico City Mexico. OBJECTIVES: To explore the possibilities and limitations of the navigation system "Stealth Station ®" during spine instrumentation in diseases that require placing of transpedieular screws and to evaluate its practical utility. METHOD: In Mexico City, D. F. at Hospital ,~ngeles del Pedregal, from July 1999 to January 2000, we reviewed retrospectively, descriptively and observationally a group of patients who required surgical management for lumbar spinal pathology, and with whom transpedicular instrumentation using the navigation system was used. Patients had to have a CT with a special protocol to diminish the distance between images so that the machine could make the tri-dimensional reconstruction more precisely. Included were patients undergoing neurosurgery and orthopedics. In the period the system was used with 25 patients with lumbosacral instrumentations. It was necessary to elongate the surgical period for an average of 35 to 40 minutes, although and there were no lesions during the procedure; the main mistakes were associated with misuse of the equipment. In this experimental phase use of fluoroscopy to verify the lateral position was agreed upon. RESULTS: Use of the equipment allowed a better tri-dimensional visualization of the vertebrae where the screw had to be placed. The equipment has accessible software that requires training for use. At present use takes time, which elongates surgical times but with further practice use times can be reduced from 15 to 20 minutes. Currently it is a very expensive resource but introduction of its virtual procedures are suggested for orthopedic applications, such as: Preoperative surgical planning, virtual procedure simulations, and use of robots to carry out hip and knee arthroplasty. CONCLUSIONS: Use of spine navigation allows the surgeon to virtually visualize anatomic conditions in a way that is not possible in conventional surgery, giving greater assurance in screw placement. When the surgeon becomes accustomed to the use of this device, fluoroscopy (radiation) is no longer required, but a learning period is required to use it correctly. It is very useful in reviewing surgeries as well as in cervical procedures which have a high risk of damaging delicate anatomic structures.
Cox,, A. Counelly t. Institute of Child Health University College London and Great Ormond St Hospital for Children London UK. Two magnetic resonance imaging (MRI) techniques, diffusion and perfusion imaging, are being used increasingly in the evaluation of the pathopysiology ofstroke(J.Cereb.Blood Flow Metab. 1998, 18:583; J.Cereb.BIood Flow Metab. 1999, 19:701 ). Diffusion M RI provides a measure of the molecular mobility of water in tissue, and early evidence of decreased diffusion is believed to be associated with the development of cytotoxic oedema which occurs as a consequence of impaired energy metabolism and loss of ion homeostasis. Perfusion MRI measures the rate at which blood is delivered to tissue and therefore represents a fundamental parameter in the evaluation of stroke. The combined use of diffusion and perfusion imaging can allow the identification of abnormalities not detected by conventional MRI techniques• and mismatches in regional abnormalities are likely to represent tissue at risk of inlhrction. This work describes our results on the use of diffusion and perfusion MRI for the investigation of tissue at risk in ischaemia in children, including 48 children with sickle cell disease. In this subgroup of patients• abnormalities on perfusion were observed in 25 cases, 9 of which had an abnormality larger than the area of infarction• and 9 had a perfusion deficit in an arterial distribution with no other MRI abnormality (conventional MRI and diffusion MRI). Some of these abnormalities have been shown to be reversible. These areas of mismatch between diffusion and perfusion abnormalities are believed to be at risk of infarction: the supply of oxygen and nutrients to the tissue is compromised, but there is still enough energy to maintain the ionic homeostasis. These MRI techniques should play an important role in investigation of children with stroke, in particular in the management of patients at high risk of stroke, such as those with sickle cell disease and moyamoya disease. Furthermore, they can contribute to the understanding of stroke and the evaluation of new therapeutic strategies.
Contact pressure distribution in supine position in low birth weight infants analyzed by photoelastic method. M. Fuiimatsu, ~hT. Fujita, ' K. Hashimoto, ~H. Nakagawa,~. "Department of Pediatrics, Nippon Medical School Second Hospital, Department of Pediatrics, Omiya Red Cross Hospital, ' Nichinan Galawn, Japan. Background: Contact pressure distribution patterns at supine position of low birth weight (LBW) neonates, were analyzed by photoelastic method. Methods: Total 61 subjects (LBW neonates, matured neonates, normal infants and Down syndrome(DS) infants) were selected. Infants were placed on a photoelastic measuring table. Photoelastic images generated in the contact regions of the body were photographed with a camera and printed on monochrome paper. The coefficient of variation in the pressure distribution Pcv value and the top and bottom ratiol~ of the trunk at the center of pressure were calculated. Results: Pcv value was significantly lower in DS than in LBW (p<0.001), matured (p<0.002), and normal infant s (p<0.01). I~ value in LBW and matured neonates were at 48.9% and 50.2%, respectively. Normal infants at 44.0% were significantly lower than in LBW neonates. However, there was no difference between LBW, and DS infants. Conclusions: Neurological impairment specifically affects the data obtained by photoelastic analysis.
Neuroimagiug - Basic neurophysiology
Value of functional magnetic resonance imaging in memory assessment in epileptic refractory patients. V.H.Machado, J.C.Da Costa, F.Santos, A. Dallacorte, C.M.Neves. PUC-RS. Porto Alegre. Rio Grande do Sul. Brazil. The intracarotid amobarbital testing (IAT) is the current gold standard method to assess language and memory lateralization in epileptic patients under assessment for epilepsy surgery, but it carries potential side effects. The Functional Magnetic Resonance Imaging (tMRI) is an potential alternative method. Our work was to compare the cerebral zones actived by memory paradigms during fMRI with the side of memory in people with epilepsy who have done IAT. Until now, we analysed the results of five patients with epilspsy. The intracarotid amobarbital testing results showed that four patients had memory predominance on the left side. When submitted to fMRI, of the first four patients who had right predominance, three of them had memory predominance on the right side also. One patient had memory predominance on the left side. The patient who had memory predominance on the left side at IAT showed memory predominance on the left side also at fMRI. These preliminary results indicate that fMRI should be an alternative method to assess memory lateralization in patients with epilipsy under assessment for epilepsy surgery, with good sensibility and specificity. Bibliography: 1) Delre J. Functional MRI lateralization of memory in temporal lobe epilepsy. Neurology 1998;50:926-932.
Functional significance of language lateralization. A. Flrel. B. Driiger, J. Sommer, C. Breitenstein, H. Heuningsen, S. Knecht Neurological University Hospital Miinster, Germany. There is limited knowledge about how brain activation during functional imaging relates to brain deactivation from lesions. We therefore compared regional cerebral perfusion increases during a language task to language performance following regional neural inhibition. Healthy individuals with predominantly left (n=7), bilateral (n=6) and right (n=7) language representation were selected from a cohort of 324 subjects in whom lateralization of language related blood perfusion increases had been determined (Brain, 1999, 122:2033-46; Brain, 2000, 123:74-81). Unihemispheric impairment of neural functioning was then elicited by transcranial magnetic stimulation (TMS) of 1Hz at 110% of motor threshold over 10 minutes. TMS has previously been shown to modulate linguistic processing when delivered over ti'ontal or parietal areas of the dominant hemisphere (J Clin Neurophysiol, 1998, 15:325-32; Neuropsychologia, 1999, 37:207-17). Inhibitory TMS of the language dominant hemisphere significantly impaired verbal processing (as measured by verbal reaction times during picture-word-matching) in subjects with unilateral (left or right) language representation. In subjects with bilateral language representation TMS of either hemisphere did not impair language function.
$45
The present study demonstrates the clinical significance of the variable language lateralization as determined by functional imaging. Language lateralization occurs along a continuum from strong left- to strong rightdominance. Therefore, the behavioral effects of neural inhibition in the sample groups with lelt-, bilateral and right-hemispheric language representation are also best viewed as part of a continuous spectrum of functional susceptibility. The side and the degree of language lateralization will therefore play an important role in determining the extent to which a patient will be affected by a language impairment after a unihemispheric lesion.
Brain a c t i v a t i o n d u r i n g s i m p l e h a n d - f i n g e r s movements vs hand writing; a functional magnetic resonance imaging study. E Pauri~, C. Del Gratta2, A. Ferretti'-, G.L. Romani 2, EM. Rossini *,3. 1: ,4faR, Ospedale Fatebenefratelli Isola T~berina, Roma, 2:ITAB. Universitdt di ChietL 3:Universith Campus Biomedico, Roma - Italy. Handwriting is a highly sophisticated cerebral function which requires a highly integrated brain-hand activity. Few investigations of this have been done using functional brain imaging methodologies. This study aimed to use fMR1 to analyze in detail the pattern of brain activation when the healthy subject is pertbrming a hand-finger movement task or is writing with a pen. Both tasks were compared when using both the dominant and the non-dominant hand. Six healthy volunteers participated in this study after informed consent had been given and the protocol had received the approval of the local Ethics Committee. All of them were right handed according to the Edinburgh Inventory. They were instructed to pertbrm two different motor tasks: a selfpaced finger tapping task, and a writing exercise. The latter consisted of writing the letter 'T' with a pen several times without interruption and without visual feedback. To detect areas of increased MR signal intensity due to the motor tasks, fMR! was performed during a rest condition and during each of the two motor tasks. Activation due to finger tapping and the writing task were statistically compared for each hand separately. The finger movements performed with the right hand induced activation of the primary motor (M 1) and sensorimotor (S 1) area; the same task pertbrmed with the left hand showed a mean activation only of the M I, even though the activated volume was higher. Writing with the right hand provoked activation of the same areas as did right finger tapping, but the Mt volume was about two and a half times larger. The M I volume activated by left-handed writing was three times larger than the finger tapping performed with the same hand, whereas the Talairach co-ordinates indicated that the localisation was the same. The supplementary motor area (SMA) was activated by both right and left hand at the same position: on the left close to the median line. Inferior parietal regions were predominantly activated by left hand writing. The cerebellum was preferentially activated by tasks performed with the left, probably because more attention is devoted to the task when the non-dominant hand is involved. The mean difference between the two motor tasks seems to be the significantly larger activation of M 1 and involvement of the parietal region luting writing. The other major finding was the involvement of the left (dominant) cerebral hemisphere in both tasks, whether performed with the right ~r the left hand.