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Cerebral Blood Volume (cerebral + blood_volume)
Kinds of Cerebral Blood Volume Selected AbstractsPerfusion parameters derived from bolus-tracking perfusion imaging are immune to tracer recirculation,JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 3 2010Jayme Cameron Kosior PhD Abstract Purpose: To investigate the impact of tracer recirculation on estimates of cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT). Materials and Methods: The theoretical model used to derive CBF, CBV, and MTT was examined. CBF and CBV estimates with and without tracer recirculation were compared in computer simulations to examine the effects of tracer recirculation. Results: The equations used to derive CBF, CBV, and MTT assume that the arterial input function and tissue tracer signals define the input and output signals, respectively, of a linear time-invariant system. As a result of the principle of superposition, these perfusion parameters are immune to tracer recirculation, which was confirmed by computer simulation. However, limited acquisition durations can lead to CBV and CBF errors of up to 50%. Conclusion: Tracer recirculation does not impact estimation of CBF, CBV, or MTT. However, previous approaches used to remove recirculation effects may be beneficial when used to compensate for limited acquisition durations in which the passage of the bolus is not adequately captured. J. Magn. Reson. Imaging 2010;31:753,756. © 2010 Wiley-Liss, Inc. [source] CBF, BOLD, CBV, and CMRO2 fMRI signal temporal dynamics at 500-msec resolutionJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 3 2008Qiang Shen PhD Abstract Purpose To investigate the temporal dynamics of blood oxygenation level-dependent (BOLD), cerebral blood flow (CBF), cerebral blood volume (CBV), and cerebral metabolic rate of oxygen (CMRO2) changes due to forepaw stimulation with 500-msec resolution in a single setting. Materials and Methods Forepaw stimulation and hypercapnic challenge on rats were studied. CBF and BOLD functional MRI (fMRI) were measured using the pseudo-continuous arterial spin-labeling technique at 500-msec resolution. CBV fMRI was measured using monocrystalline iron-oxide particles following CBF and BOLD measurements in the same animals. CMRO2 change was estimated via the biophysical BOLD model with hypercapnic calibration. Percent changes and onset times were analyzed for the entire forepaw somatosensory cortices and three operationally defined cortical segments, denoted Layers I,III, IV,V, and VI. Results BOLD change was largest in Layers I,III, whereas CBF, CBV, and CMRO2 changes were largest in Layers IV,V. Among all fMRI signals in all layers, only the BOLD signal in Layers I,III showed a poststimulus undershoot. CBF and CBV dynamics were similar. Closer inspection showed that CBV increased slightly first (P < 0.05), but was slow to peak. CBF increased second, but peaked first. BOLD significantly lagged both CBF and CBV (P < 0.05). Conclusion This study provides important temporal dynamics of multiple fMRI signals at high temporal resolution in a single setting. J. Magn. Reson. Imaging 2008. © 2008 Wiley-Liss, Inc. [source] High cerebral blood volume in human gliomas predicts deletion of chromosome 1p: Preliminary results of molecular studies in gliomas with elevated perfusionJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 6 2007Meng Law MD Abstract Purpose To determine if increased perfusion using dynamic susceptibility contrast perfusion MRI (DSC MRI) in gliomas may be predictive of 1p19q deletions. Loss of heterozygosity of chromosomes 1p and 19q confers responsiveness to chemotherapy improving survival in gliomas. Materials and Methods We retrospectively reviewed 16 patients who had DSC MRI and molecular studies of their excised gliomas for 1p19q deletions. Allelic status was assessed by loss of heterozygosity using polymerase chain reaction (PCR). DNA was extracted from paraffin curls of brain tumor sections and nail clippings. Relative cerebral blood volume (rCBV) measurements were then statistically compared with the presence of 1p and 19q deletions. Results Patients with 1p19q deletions (N = 7) demonstrated rCBV values of 10.54 ± 2.93. Patients without 1p deletions (N = 9) had rCBV values of 4.84 ± 2.4 (P = 0.012). Logistic regression demonstrated that rCBV was able to predict the presence of a 1p deletion to significance levels of 0.038 and 0.044, adjusted and not adjusted for age and sex, respectively. The kappa coefficient for the agreement between predicted deletion status using rCBV and the truedeletion status was 0.746 (P = 0.0028). Deletions of 19q alone, or together with 1p deletions, were not associated with high rCBV. Conclusion Histopathologic, molecular, and imaging evidence supports increased neovascularity in gliomas with 1p deletions in this preliminary study. We propose a diagnostic algorithm to obtain molecular studies in gliomas demonstrating high rCBV. J. Magn. Reson. Imaging 2007;25:1113,1119. © 2007 Wiley-Liss, Inc. [source] Calculation of cerebral perfusion parameters using regional arterial input functions identified by factor analysisJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2006Linda Knutsson MS Abstract Purpose To calculate regional cerebral blood volume (rCBV), regional cerebral blood flow (rCBF), and regional mean transit time (rMTT) accurately, an arterial input function (AIF) is required. In this study we identified a number of AIFs using factor analysis of dynamic studies (FADS), and performed the cerebral perfusion calculation pixel by pixel using the AIF that was located geometrically closest to a certain voxel. Materials and Methods To verify the robustness of the method, simulated images were generated in which dispersion or delay was added in some arteries and in the corresponding cerebral gray matter (GM), white matter (WM), and ischemic tissue. Thereafter, AIFs were determined using the FADS method and simulations were performed using different signal-to-noise ratios (SNRs). Simulations were also carried out using an AIF from a single pixel that was manually selected. In vivo results were obtained from normal volunteers and patients. Results The FADS method reduced the underestimation of rCBF due to dispersion or delay that often occurs when only one AIF represents the entire brain. Conclusion This study indicates that the use of FADS and the nearest-AIF method is preferable to manual selection of one single AIF. J. Magn. Reson. Imaging 2006. © 2006 Wiley-Liss, Inc. [source] Susceptibility Contrast and Arterial Spin Labeled Perfusion MRI in Cerebrovascular DiseaseJOURNAL OF NEUROIMAGING, Issue 1 2003Ronald L. Wolf MD ABSTRACT Purpose. To directly compare dynamic susceptibility contrast (DSC) and continuous arterial spin labeled (CASL) magnetic resonance (MR) perfusion techniques in patients with known cerebrovascular disease, with the goals of identifying possible pitfalls in interpretation and determining potential for a complementary role in this setting. Methods. DSC and CASL MR perfusion studies were performed and compared in 11 patients with acute and/or chronic cerebrovascular disease. Using an automated segmentation technique, Pearson correlation coefficients were generated for CASL perfusion measurements compared to DSC perfusion maps (time-to-peak [TTP], relative cerebral blood volume [rCBV], cerebral blood flow [rCBF], and mean transit time [MTT]) by hemisphere and vascular territory. Results. TTP maps obtained using DSC perfusion MR correlated best both subjectively and objectively with CASL perfusion MRmeasurements when all patients studied were considered. If patients with a major transit delay were excluded, DSC rCBF correlated best with CASL CBF measurements. Conclusion. There may be a complementary role for CASL and DSC perfusion MR methods in cerebrovascular disease, especially in the setting of a marked transit delay. [source] Applications and limitations of whole-brain MAGIC VASO functional imagingMAGNETIC RESONANCE IN MEDICINE, Issue 2 2007A. Scouten Abstract This work extends the multiple acquisitions with global inversion cycling vascular space occupancy (MAGIC VASO) method to human whole-brain functional magnetic resonance imaging (fMRI) at 3.0 Tesla and demonstrates the need to consider the dynamic contribution of cerebrospinal fluid (CSF) to the relative VASO signal change (,VASO/VASO). Simulations were performed to determine the optimal slice number between global inversions, and correction factors were obtained to account for incomplete blood nulling in particular slices. The necessity of an accurate estimate of resting cerebral blood volume (CBVrest) is discussed in the context of ,CBV/CBV calculations. A three-compartment model is proposed to include both the resting and changing fractional CSF contribution (xc,rest and ,xc, respectively) to ,VASO/VASO. A MAGIC VASO sequence that provides whole-brain coverage is demonstrated using a paradigm comprised of visual, motor, and auditory stimulation. Activated regions are quantitatively compared in the corresponding blood oxygenation level-dependent (BOLD) images. Estimates of the minimum ,CBV/CBV resulting from motor and visual stimulation were comparable to previous findings at 17 ± 8% (N = 8) and 19 ± 9% (N = 6), respectively. The absence of VASO activation for auditory stimulation and evidence of activation-induced decreases in CSF volume fraction around the insula and superior temporal gyrus support the possibility of a ,xc contribution to the VASO signal. Without specific knowledge of the CSF components (xc,rest and ,xc), inference of ,CBV/CBV from ,VASO/VASO is severely limited. Magn Reson Med 58:306,315, 2007. © 2007 Wiley-Liss, Inc. [source] Bicuculline-induced brain activation in mice detected by functional magnetic resonance imagingMAGNETIC RESONANCE IN MEDICINE, Issue 2 2001Thomas Mueggler Abstract Dynamic measurements of local changes in relative cerebral blood volume (CBVrel) during a pharmacological stimulation paradigm were performed in mice. Using magnetite nanoparticles as an intravascular contrast agent, high-resolution CBVrel maps were obtained. Intravenous administration of the GABAA antagonist bicuculline prompted increases in local CBVrel as assessed by MRI with a high spatial resolution of 0.2 × 0.2 mm2 and a temporal resolution of 21 s. Signal changes occurred 20,30 s after the onset of drug infusion in the somatosensory and motor cortex, followed by other cortical and subcortical structures. The magnitudes of the CBVrel increases were 18% ± 4%, 46% ± 14%, and 67% ± 7%, as compared to prestimulation values for the cortex, and 9% ± 3%, 25% ± 4%, and 36% ± 7% for the caudate putamen for bicuculline doses of 0.6, 1.25, and 1.5 mg/kg, respectively. On-line monitoring of transcutaneous carbon dioxide tension PtcCO2 reflecting arterial PaCO2 did not show any alteration during the stimulation paradigm. One of five of the mice receiving the highest bicuculline dose, and three of seven receiving the intermediate dose displayed a different cortical response pattern. After a CBVrel increase of 40% lasting for approximately 1 min, significant CBVrelreductions by 80% have been observed. Subcortical structures did not display this behavior. The present study suggests that this noninvasive approach of functional MRI (fMRI) can be applied to study drug-induced brain activation by central nervous system (CNS) drugs in mice under normal and pathological situations. Magn Reson Med 46:292,298, 2001. © 2001 Wiley-Liss, Inc. [source] Using forward calculations of the magnetic field perturbation due to a realistic vascular model to explore the BOLD effectNMR IN BIOMEDICINE, Issue 6 2008José P. Marques Abstract This paper assesses the reliability of the infinite cylinder model used previously in the literature to simulate blood oxygenation level dependent (BOLD) signal changes. A three-dimensional finite element method was applied to a realistic model of the cortical vasculature, and the results compared with those generated from a simple model of the vasculature as a set of independent, randomly oriented, infinite cylinders. The realistic model is based on scanning electron microscopy measurements of the terminal vascular bed in the superficial cortex of the rat. Good agreement is found between the two models with regard to the extravascular R2* and R2 dependence on the cerebral blood volume and blood oxygenation fraction. Using the realistic model, it is also possible to gain further understanding of the relative importance of intravascular and extravascular BOLD contrast. A simple parameterisation of the dependence of the relaxation rates on relative cerebral blood volume and blood,tissue susceptibility difference was carried out, allowing discussion of the variation in the form of the haemodynamic response with field strength. Copyright © 2007 John Wiley & Sons, Ltd. [source] Modeling dynamic cerebral blood volume changes during brain activation on the basis of the blood-nulled functional MRI signalNMR IN BIOMEDICINE, Issue 7 2007Changwei W. Wu Abstract Recently, vascular space occupancy (VASO) based functional magnetic resonance imaging (fMRI) was proposed to detect dynamic cerebral blood volume (CBV) changes using the blood-nulled non-selective inversion recovery (NSIR) sequence. However, directly mapping the dynamic CBV change by the NSIR signal change is based on the assumption of slow water exchange (SWE) around the capillary regime without cerebral blood flow (CBF) effects. In the present study, a fast water exchange (FWE) model incorporating with flow effects was derived from the Bloch equations and implemented for the quantification of dynamic CBV changes using VASO-fMRI during brain activation. Simulated results showed that only subtle differences in CBV changes estimated by these two models were observed on the basis of previously published VASO results. The influence of related physiological and biophysical factors within typical ranges was evaluated in steady-state simulations. It was revealed that in the transient state the CBV curves could be delayed in comparison with measured NSIR curves owing to the imbalance between the inflowing and outflowing blood signals. Copyright © 2007 John Wiley & Sons, Ltd. [source] Quantitative characterization of hemodynamic properties and vasculature dysfunction of high-grade gliomasNMR IN BIOMEDICINE, Issue 6 2007Vijaya Nagesh Abstract Aberrations in tumor and peritumoral vasculature may not be distinguishable by cerebral blood flow (CBF) or cerebral blood volume (CBV) alone. The relationships between CBF and CBV were examined to estimate vasculature-specific hemodynamic characteristics. Twenty glioma patients were studied with dynamic susceptibility T2*-weighted MRI [(dynamic contrast-enhanced magnetic resonance imaging (DSC-MRI)] before and during week 1 and 3 of radiotherapy (RT). CBF and CBV were calculated from DSC-MRI, and relationships between the two were evaluated: the physiological measure of mean transit time (MTT),=,CBV/CBF; empirical fitting using the power law CBV,=,constant,×,(CBF),. Three different tissue types were assessed: the Gd-enhancing tumor volume (GEV); non-enhanced abnormal tissue located beyond GEV but within the abnormal hyperintense region on FLAIR images (NEV); normal tissue in the hemisphere contralateral to the tumor (CNT). The effects of tissue types, CBV magnitudes (low, medium and high), before and during RT, on MTT and , were analyzed by analysis of variance (ANOVA). The MTT and , for the three tissue types were significantly different (p,<,0.009). MTT increased from CNT (1.60,s) to NEV (1.93,s) to GEV (2.28,s) (p,<,0.0005). , was significantly greater in GEV (1.079) and NEV (1.070) than in CNT (1.025). , increased with increasing CBV magnitude while MTT was independent of CBV magnitude. There was a significant decrease in MTT of NEV and GEV during week 3 of RT compared with pre-RT values for all CBV magnitudes. There was a significant increase in , during RT in the tumor and peritumor. Progressive abnormalities in vasculature and hemodynamic characteristics of the vascular bed were delineated, with significant disorder in the tumor but mild abnormality in peritumoral tissue. Copyright © 2007 John Wiley & Sons, Ltd. [source] Endogenous functional CBV contrast revealed by diffusion weightingNMR IN BIOMEDICINE, Issue 8 2006Todd B. Harshbarger Abstract Functional MRI (fMRI) based on the blood oxygenation level dependent (BOLD) contrast often suffers from a lack of specificity because of the vascular spread of oxygenation changes. It is suggested from the optical imaging and animal fMRI literature that cerebral blood volume (CBV) changes are more closely tied to the smaller vessels. As such, fMRI contrast based on CBV changes will have improved spatial specificity to the neuronal activities as they are immediately adjacent to the smaller vessels. In this paper, an endogenous contrast mechanism based on a diffusion weighting strategy that could detect functional CBV changes is presented. Initially, a theoretical framework is presented to model the functional signal changes as a function of CBV under diffusion weighting, which predicts peak CBV sensitivity at various vessel,tissue mixtures. It was found that a b factor over 1500,s/mm2 would be necessary to achieve dominant CBV contrast. Further, two sets of experimental results are also presented. In the first experiment, diffusion weighting at a set of b factors ranging from 300 to 600,s/mm2 was used. The results indicated that while the positive activation (predominantly BOLD signal) continued to reduce in magnitude and spatial extent, the negative activation (predominantly CBV signal) remained virtually constant with increasing b factors. The second experiment used a b factor of 1600,s/mm2 and showed extensive negative activation in the visual cortex and greatly reduced positive activations compared with images with no diffusion weighting. The time course of negative activation showed a faster time to peak and return to baseline than the positive BOLD activity, consistent with the small vessel origin of the signal changes. These results suggest that appropriate diffusion weighting could be used to measure activation related CBV changes. Copyright © 2006 John Wiley & Sons, Ltd. [source] Longitudinal mapping of mouse cerebral blood volume with MRINMR IN BIOMEDICINE, Issue 5 2006Herman Moreno Abstract MRI estimations of cerebral blood volume (CBV), useful in mapping brain dysfunction, typically require intravenous (IV) injections of contrast agents. Transgenically engineered mice have emerged as the dominant animal model with which to investigate disorders of the brain and novel therapeutic agents. The difficulty in gaining IV access in mice prohibits repeated administration of contrast in the same animal, limiting the ability to map CBV changes over time. Here we address this limitation by first optimizing an approach for estimating CBV that relies on intraperitoneal (IP) rather than IV injections of the contrast agent gadodiamide. Next, we show that CBV maps generated with IP or IV injections are quantitatively comparable. Finally, we show that CBV maps generated with IP gadodiamide can be acquired repeatedly, reliably and safely over time. Although this approach has certain limitations, estimating CBV with IP injections is well-suited for mapping the spatiotemporal pattern of brain dysfunction in mice models of disease, and for testing pharmacological agents. Copyright © 2006 John Wiley & Sons, Ltd. [source] Surgical closure of patent ductus arteriosus reduces the cerebral tissue oxygenation index in preterm infants: a near-infrared spectroscopy and Doppler studyPEDIATRICS INTERNATIONAL, Issue 3 2006PATRIZIA ZARAMELLA Abstract Background: The aim of this study was to investigate the effects of patent ductus arteriosus (PDA) ligature on cerebral oxygen saturation, cerebral blood volume (CBV) and cerebral blood flow velocity by means of near-infrared spectroscopy (NIRS) and transcranial Doppler simultaneous examinations. Methods: This is an observational study considering 16 babies of gestational age 24,34 weeks diagnosed with PDA who underwent surgical ligation. The cerebral oxygen saturation, CBV and blood gases values were obtained 35 min before ligation, so also around the 14th and 27th min after the clip's insertion. Results: Cerebral oxygen saturation, measured as tissue oxygenation index (TOI), decreased significantly after PDA ligation from a basal value of 61.1 (3.8) before surgery to 56.6 (3.3) and 55.8 (2.6)%, for the 14th and 27th min, respectively (P < 0.04). CBV before and after clipping was unvaried. A negative correlation was found between ,pH and ,CBV after ligation (R = 0.52, P = 0.03), whilst a positive correlation was found between ,CBV and ,PaCO2 (R = 0.62, P = 0.009). pH increased at the 27th min post-ligation. Conclusions: NIRS is a tool for obtaining information on cerebral oxygen saturation and CBV changes during surgical PDA ligation at the bedside. A fall in TOI suggests an increased oxygen extraction during PDA surgery. The lack of increase in ,CBV or in diastolic flow velocity show that the PDA before the clipping did not limit cerebral blood flow, the drop in TOI suggests increased oxygen consumption over the clip and the need for accurate monitoring of oxygen utilization after the surgical treatment. [source] Perfusion computed tomography in the acute phase of mild head injury: Regional dysfunction and prognostic value,ANNALS OF NEUROLOGY, Issue 6 2009Zwany Metting MD Objective Traumatic brain injury is a major cause of disability and death. Most patients sustain a mild head injury with a subgroup that experiences disabling symptoms interfering with return to work. Brain imaging in the acute phase is not predictive of outcome, as 20% of noncontrast computed tomographic (CT) scans on admission is normal in patients with a suboptimal outcome. The aim of this study was to perform perfusion CT imaging in the acute phase of mild head injury in patients without intracranial abnormalities on the noncontrast CT, to assess whether these patients had cerebral perfusion abnormalities. Furthermore, the relation between perfusion CT parameters and severity of head injury and outcome was evaluated. Methods In patients with mild head injury and normal noncontrast CT, perfusion CT was performed directly after admission. The perfusion data were compared with data of 25 healthy control subjects. Outcome was determined 6 months after injury with the extended Glasgow Coma Outcome Scale score and return to work. Results Seventy-six patients were included. In patients with a decreased Glasgow Coma Scale score, a significant decrease of cerebral blood flow and cerebral blood volume was detected in the frontal and occipital gray matter. In logistic regression analyses, decreased cerebral blood flow and cerebral blood volume in the frontal lobes predicted worse outcome according to the extended Glasgow Coma Outcome Scale score. CT perfusion parameters did not predict return to work. Interpretation In the acute phase of mild head injury, disturbed cerebral perfusion is seen in patients with normal noncontrast CT correlating with severity of injury and outcome. Ann Neurol 2009;66:809,816 [source] Haemodynamic changes in the brain after vaginal delivery and caesarean section in healthy term infantsBJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 2 2002C. Dani Objective To investigate whether the mode of delivery may affect neonatal cerebral haemodynamics during the first hour of life. Design Prospective study. Sample Healthy infants with gestational age ,37 weeks and birthweight appropriate for gestational age, born after uncomplicated pregnancy by vaginal delivery or elective caesarean section, two to five hours after the delivery. Methods Near infra-red spectroscopy was used to measure changes of oxygenated haemoglobin, deoxygenated haemoglobin, oxidized-reduced cytochrome aa3, and mean cerebral oxygen saturation (mixed cerebral oxygen saturation = oxygenated haemoglobin/total haemoglobin). Changes in cerebral blood volume were calculated. Results Near infra-red spectroscopy data did not show significant differences between infants born by vaginal delivery or by caesarean section. There was a significant decrease of oxygenated haemoglobin and change of cerebral blood volume values at 120 and 180 minutes in both the groups, while deoxygenated haemoglobin and oxidized-reduced cytochrome aa3 were unchanged. Conclusions A decrease of cerebral blood volume occurs after birth and this occurs both in infants born by vaginal delivery and by caesarean section. [source] Quantitative study on cerebral blood volume determined by a near-infrared spectroscopy during postural change in childrenACTA PAEDIATRICA, Issue 3 2009Yasuko Taeja Kim Abstract Aim: To investigate changes in cerebral blood volume during standing in healthy children with or without abnormal cardiovascular responses. Methods: We studied 53 children (age, 10,15 years). Cerebral oxygenated haemoglobin (oxy-Hb) and deoxygenated Hb (deoxy-Hb) were non-invasively and continuously measured using near-infrared spectroscopy (NIRS) (NIRO 300, Hamamatsu Photomedics, Shizuoka, Japan) during active standing. Beat-to-beat arterial pressure was monitored by Portapres. Results: Of 49 children with complete data acquisition, 33 had a normal cardiovascular response to the test (Group I) and 16 showed an abnormal response (Group II); nine with instantaneous orthostatic hypotension, three with postural tachycardia syndrome, three with neutrally mediated syncope and one with delayed orthostatic hypotension. At the onset of standing, Group II showed a significantly larger fall of oxy-Hb than Group I did (,2.9 ± 2.8 ,mol/L vs. ,6.4 ± 7.2 ,mol/L, respectively, p < 0.05). During min 1 to 7 of standing, with one exception, changes in oxy-Hb were normally distributed over the level of ,4 ,mol/L in Group I. Group II also showed a significantly marked decrease in oxy-Hb compared to Group I. Decreases in oxy-Hb were not correlated with blood pressure changes. Conclusion: This study shows that precise change in cerebral blood volume caused by orthostatic stress can be determined by NIRS in children in a quantitative manner of NIRS. Children with abnormal circulatory responses to standing showed a significant reduction of oxy-Hb compared with normal counterparts, suggesting impairment of cerebral autoregulation in these children. [source] Rehabilitation with dental prosthesis can increase cerebral regional blood volumeCLINICAL ORAL IMPLANTS RESEARCH, Issue 6 2005Ikuya Miyamoto Abstract: Treatment with denture for edentulous people is highly important for maintaining quality of life. However, its effect on the brain is unknown. In this experimental study, we hypothesized that dental prosthesis can recover not only the physical condition of mastication system but also the regional brain activity. We evaluated functional brain imaging of edentulous subjects fixed by dental implant prosthesis with clenching tasks by multi-channel near-infrared optical topography. Results revealed a significantly (P<0.001; paired t -test) increased cerebral regional blood volume during maximum voluntary clenching task by implant-retained prosthesis. There were no statistically significant differences between patients with and without prosthesis in the latency to the maximum regional blood volume after the task. Conclusively, clenching can be effective for increasing cerebral blood volume; accordingly maintenance of normal chewing might prevent the brain from degenerating. Résumé Le traitement par prothèses des édentés est extrêmement important pour garder la qualité de vie. Cependant, son effet sur le cerveau est inconnu. Dans cette étude expérimentale, l'hypothèse qui a étéémise concernait les prothèses dentaires et leur aptitude à rétablir non seulement la condition physique du système masticatoire mais également l'activité cérébrale régionale. L'imagerie du cerveau fonctionnel de l'édenté avec des prothèses sur implants avec travail de serrage par topographie optique près de l'infrarouge à multiple canaux. Les résultats ont révélé une augmentation significative (P<0.001/test-t par paires) de la circulation sanguine régionale cérébrale durant la force de serrage volontaire maximale par les prothèses retenues sur implants. Il n'y avait aucune différence significative entre les avec et sans prothèses dans le temps de latence jusqu'à la circulation sanguine régionale maximale après le serrage. Le serrage peut être efficace pour augmenter la circulation sanguine cérébrale et donc le maintien d'une mastication normale pourrait prévenir toute dégénérescence cérébrale. Zusammenfassung Die Versorgung mit Prothesen bei zahnlosen Patienten ist sehr wichtig, um die Lebensqualität zu erhalten. Der Einfluss auf das Gehirn ist jedoch nicht bekannt. In dieser experimentellen Studie stellten wir die Hypothese auf, dass eine dentale Prothese nicht nur den physischen Zustand des Kausystems wieder herstellen kann, sondern auch die regionale Hirnaktivität beeinflusst. Wie untersuchten funktionelle Gehirnbilder von zahnlosen Subjekten mit auf Implantaten befestigten Prothesen, welche Aufgaben beim Zusammenbeissen erledigen mussten, mittels multi-kanal optischer Topographie nahe am Infrarotbereich. Die Resultate zeigten einen signifikanten (P<0.001; gepaarter t -Test) Anstieg in der regionalen cerebralen Durchblutung während des Maximums beim freiwilligen Zusammenbeissen mit der auf Implantaten befestigten Prothese. Es bestanden keine statistisch signifikanten Unterschiede in der Latenzzeit bis zur maximalen regionalen Durchblutung nach Erfüllung der Aufgabe mit oder ohne Prothese. Es wird die Schlussfolgerung gezogen, dass das Zusammenbeissen zu einem Ansteigen der cerebralen Durchblutung führen kann. Daher könnte der Erhalt einer normalen Kaufunktion einer Degeneration des Gehirn entgegenwirken. Resumen El tratamiento con dentaduras para personas edéntulas es altamente importante para conservar la calidad de vida. En este estudio experimental, hemos hipotizado que las prótesis dentales pueden recuperar no solo las condiciones físicas del sistema masticatorio sino también la actividad cerebral regional. Hemos evaluado las imágenes funcionales del cerebro de pacientes edéntulos rehabilitados por prótesis implantosoportadas con tareas de apretado por medio de topografía óptica casi-infrarroja multicanal. Los resultados revelaron un flujo sanguíneo cerebral regional significativamente (P<0.001; t -test pareado) aumentado durante la mordida máxima voluntaria con prótesis implantosoportada. No hubo diferencias estadísticamente significativas entre con o sin prótesis en la latencia al flujo sanguíneo regional tras la tarea. En conclusión, el apretado puede ser efectivo para incrementar el flujo sanguíneo cerebral; en consecuencia, el mantenimiento de una masticación normal puede prevenir la degeneración cerebral. [source] Methodology of brain perfusion imagingJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2001Emmanuel L. Barbier PhD Abstract Numerous techniques have been proposed in the last 15 years to measure various perfusion-related parameters in the brain. In particular, two approaches have proven extremely successful: injection of paramagnetic contrast agents for measuring cerebral blood volumes (CBV) and arterial spin labeling (ASL) for measuring cerebral blood flows (CBF). This review presents the methodology of the different magnetic resonance imaging (MRI) techniques in use for CBV and CBF measurements and briefly discusses their limitations and potentials. J. Magn. Reson. Imaging 2001;13:496,520. © 2001 Wiley-Liss, Inc. [source] | |||||||||||||||||||||||||