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MRI Assessment (mri + assessment)
Selected AbstractsCorticothalamic Modulation during Absence Seizures in Rats: A Functional MRI AssessmentEPILEPSIA, Issue 9 2003Jeffrey R. Tenney Summary:,Purpose: Functional magnetic resonance imaging (fMRI) was used to identify areas of brain activation during absence seizures in an awake animal model. Methods: Blood-oxygenation-level,dependent (BOLD) fMRI in the brain was measured by using T2*-weighted echo planar imaging at 4.7 Tesla. BOLD imaging was performed before, during, and after absence seizure induction by using ,-butyrolactone (GBL; 200 mg/kg, intraperitoneal). Results: The corticothalamic circuitry, critical for spike,wave discharge (SWD) formation in absence seizure, showed robust BOLD signal changes after GBL administration, consistent with EEG recordings in the same animals. Predominantly positive BOLD changes occurred in the thalamus. Sensory and parietal cortices showed mixed positive and negative BOLD changes, whereas temporal and motor cortices showed only negative BOLD changes. Conclusions: With the BOLD fMRI technique, we demonstrated signal changes in brain areas that have been shown, with electrophysiology experiments, to be important for generating and maintaining the SWDs that characterize absence seizures. These results corroborate previous findings from lesion and electrophysiological experiments and show the technical feasibility of noninvasively imaging absence seizures in fully conscious rodents. [source] MRI Assessment Followed by Successful Mechanical Recanalization of a Complete Tandem (Internal Carotid/Middle Cerebral Artery) Occlusion and Reversal of a 10-Hour Fixed DeficitJOURNAL OF NEUROIMAGING, Issue 1 2008Catalina C. Ionita MD ABSTRACT BACKGROUND Mechanical clot extraction up to 8 hours after stroke onset is an alternative strategy for opening large vessels, especially for patients ineligible for intravenous thrombolysis. Safety beyond this therapeutic window is untested. METHODS An 81-year-old woman presented 8 hours after she developed left-sided weakness and dysarthria with a National Institutes of Health Stroke Scale (NIHSS) score fluctuating between 6 and 13. Neuroimaging revealed a large perfusion deficit with no diffusion abnormalities. An emergent cerebral angiogram revealed a complete internal carotid artery terminus occlusion. RESULTS Successful mechanical thrombectomy was performed without complication and resulted in almost complete reversal of the patient's deficit to an NIHSS score of 1, 10 hours after stroke onset. CONCLUSION Patients with large hypoperfused areas and minimal diffusion abnormalities on the MRI may benefit from mechanical thrombectomy beyond an 8-hour window. [source] Ophthalmological, cognitive, electrophysiological and MRI assessment of visual processing in preterm children without major neuromotor impairmentDEVELOPMENTAL SCIENCE, Issue 5 2010Michelle O'Reilly Many studies report chronic deficits in visual processing in children born preterm. We investigated whether functional abnormalities in visual processing exist in children born preterm but without major neuromotor impairment (i.e. cerebral palsy). Twelve such children (< 33 weeks gestation or birthweight < 1000 g) without major neuromotor impairment and 12 born full-term controls were assessed at 8,12 years of age by means of ophthalmological assessment (visual acuity, colour vision, stereopsis, stereoacuity, visual fields, ocular motility, motor fusion), cognitive tests of visual-motor, visual-perceptual and visual-spatial skills and pattern-reversal visual evoked potentials (PR-VEPs). All participants also underwent magnetic resonance imaging (MRI) of the brain and neuromotor assessments. No significant differences were found between the groups on the ophthalmological, visual cognitive, neurological, neuromotor or MRI measures. The P100 component of the PR-VEP showed a significantly shorter latency in the preterm compared with the full-term participants. Whilst this P100 finding suggests that subtle abnormalities may exist at the neurophysiological level, we conclude that visual dysfunction is not systematically associated with preterm birth in the context of normal neurological status. [source] Three-dimensional MRI assessment of regional wall stress after acute myocardial infarction predicts postdischarge cardiac eventsJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 3 2008Fabrice Prunier MD Abstract Purpose To determine the prognostic significance of systolic wall stress (SWS) after reperfused acute myocardial infarction (AMI) using MRI. Materials and Methods A total of 105 patients underwent MRI 7.8 ± 4.2 days after AMI reperfusion. SWS was calculated by using a three-dimensional (3D) MRI approach to left ventricular (LV) wall thickness and to the radius of curvature. Between hospital discharge and the end of follow-up, an average of 4.1 ± 1.7 years after AMI, 19 patients experienced a major cardiac event, including cardiac death, nonfatal reinfarction or heart failure (18.3%). Results The results were mainly driven by heart failure outcome. In univariate analysis the following factors were predictive of postdischarge major adverse cardiac events: 1) at the time of AMI: higher heart rate, previous calcium antagonist treatment, in-hospital congestive heart failure, proximal left anterior descending artery (LAD) occlusion, a lower ejection fraction, higher maximal ST segment elevation before reperfusion, and ST segment reduction lower than 50% after reperfusion; 2) MRI parameters: higher LV end-systolic volume, lower ejection fraction, higher global SWS, higher SWS in the infarcted area (SWS MI) and higher SWS in the remote myocardium (SWS remote). In the final multivariate model, only SWS MI (odds ratio [OR]: 1.62; 95% confidence interval [CI]: 1.01,2.60; P = 0.046) and SWS remote (OR: 2.17; 95% CI: 1.02,4.65; P = 0.046) were independent predictors. Conclusion Regional SWS assessed by means of MRI a few days after AMI appears to be strong predictor of postdischarge cardiac events, identifying a subset of at risk patients who could qualify for more aggressive management. J. Magn. Reson. Imaging 2008. © 2008 Wiley-Liss, Inc. [source] Proton and sodium MRI assessment of fluid level in calf tissueJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 1 2006Chun S. Zuo PhD Abstract Purpose To investigate the feasibility of using 1H and 23Na MRI to detect fluid levels in the lower leg muscle. Materials and Methods Proton and sodium MRI was applied to detect body fluid levels in the lower leg muscles of 18 healthy young male subjects at 3T and 4T. The paradigms under investigation were a postural change from sitting upright to lying supine, and saline infusion. Results We found that the average proton MR signal in gastrocnemius and soleus muscles were reduced following the postural change by 3.5% ± 1.4% (P < 0.05) and rose following saline infusion by 3.7% ± 0.9% (P < 0.01). More dramatically, the sodium MR signal decreased by 7.1% ± 1.2% (P < 0.01) following the postural change and increased following saline infusion by 12% ± 3.8% (P < 0.05). The ratio of intra- to extracellular fluid levels was 1.6 ± 0.5 for the subjects based on the acquired proton and sodium data. Conclusion Our results indicate that proton and sodium MRI can be used to assess fluid levels in the lower extremities, and this technique may be applied to evaluate fluid retention. J. Magn. Reson. Imaging 2006. © 2006 Wiley-Liss, Inc. [source] Assessment of the effect of 2-chloroadenosine in normal rat brain using spin-labeled MRI measurement of perfusionMAGNETIC RESONANCE IN MEDICINE, Issue 5 2001Patrick M. Kochanek Abstract Adenosine analogs such as 2-chloroadenosine are potent cerebrovasodilators. Spin-labeled MRI was used to investigate the spatial distribution, dose-response, and timing of the effect of 2-chloroadenosine on cerebral blood flow (CBF) after intraparenchymal injection into rat brain. Sprague-Dawley rats (N = 10) were injected with 2-chloroadenosine at doses of 0.3, 6.0, or 12 nmoles, or saline vehicle (2,4 ,L). CBF was serially quantified in a slice through the injection site in a circular (3.6 mm diameter) region of interest (ROI) around the injection and in ipsilateral hemispheric ROIs at ,90 min and ,180 min. Marked 3.77- and 3.93-fold increases in CBF (vs. vehicle) were seen in the circular ROI at ,90 min and ,180 min after 12-nmol injection, respectively. Similarly, 2.92- and 2.78-fold increases in hemispheric CBF were observed at ,90 min and ,180 min, respectively, after injection of 12 nmoles. Linear dose-response relationships were observed at both times after injection in both ROIs (all P < 0.01). Spin-labeling MRI assessment revealed that parenchymal injection of 2-chloroadenosine produces potent, dose-dependent, and sustained vasodilation over large areas of brain. This treatment and imaging paradigm should facilitate investigation of the effect of CBF promotion in models of traumatic and ischemic brain injury. Magn Reson Med 45:924,929, 2001. © 2001 Wiley-Liss, Inc. [source] Functional Magnetic Resonance Imaging Using Iron Oxide Particles in Characterizing Head and Neck Adenopathy,THE LARYNGOSCOPE, Issue 9 2000Henry T. Hoffman MD Abstract Objectives In lymph nodes harboring metastases the reticuloendothelial system is replaced by tumor cells and does not concentrate iron particles. This study assesses the value of contrast magnetic resonance imaging (MRI) using ultrasmall superparamagnetic iron oxide particles (Combidex, Advanced Magnetics, Inc., Cambridge, MA) to characterize and stage neck nodes. Study Design Prospective analysis of neck imaging by Combidex MRI, with correlation from pathological assessment of resected lymph nodes. Methods Nine patients underwent MRI and subsequent bilateral neck dissections (three), unilateral neck dissections (five) or fine-needle aspiration (one). Each case was evaluated for the number, location, MRI characteristics, and pathological assessment of lymph nodes. Results Forty-nine separate nodal levels were evaluated with both Combidex MRI and pathological assessment. The presence of metastatic nodal involvement among 45 levels was correctly assessed by the Combidex MRI (three false-negative results, one false-positive result; sensitivity, 84%; specificity, 97%). Analysis was possible for 101 of the individual lymph nodes identified by MRI that could be correlated with individual nodes pathologically examined. Combidex MRI assessment was correct for 99 nodes (one-false positive result, one false-negative result; sensitivity, 95%, specificity, 99%). Standard MRI interpretation without Combidex identified that 12 of 18 nodes (67%) that were greater than or equal to 10 mm (greatest dimension) contained tumor, whereas 9 of 83 nodes (11%) that were less than 10 mm contained tumor. Conclusions Combidex MRI provides functional information to characterize lymph nodes in the clinical staging of squamous cell carcinoma of the head and neck. The inability of MRI to identify small lymph nodes restricts the usefulness of this technique. [source] Is 18F-fluorodeoxyglucose positron emission tomography scanning a reliable way to assess disease activity in takayasu arteritis?ARTHRITIS & RHEUMATISM, Issue 4 2009Laurent Arnaud Objective 18F-fluorodeoxyglucose,positron emission tomography (FDG-PET) scanning has been proposed as a new way of assessing disease activity in Takayasu arteritis (TA), but previous studies have used the nonvalidated National Institutes of Health (NIH) global activity criteria, and thus might be biased. This study was undertaken to determine the value of PET scanning for assessment of disease activity in TA, by comparing PET scan data with clinical, biologic, and magnetic resonance imaging (MRI) data assessed separately. Methods Twenty-eight patients with TA (according to the American College of Rheumatology criteria) underwent a total of 40 PET scans. Images were reviewed by 2 pairs of independent nuclear medicine physicians and assessed for pattern and intensity of vascular uptake. TA activity data were obtained within 15 days of the PET scans. Results PET scanning revealed abnormal vascular uptake in 47% of the 40 examinations. The uptake intensity grade was 0 in 7 scans, grade 1 in 7 scans, grade 2 in 13 scans, and grade 3 in 13 scans. Morphologic analysis was conducted by grading the pattern of the vascular uptake as diffuse (73%), segmental (20%), or focal (13%). There was a trend toward an association between clinically active disease and the semiquantitative assessment of FDG uptake (P = 0.08). We found no statistical association between levels of acute-phase reactants and intensity of uptake. There was no significant association between the semiquantitative assessment of FDG uptake and the presence of vascular wall thickening (P = 0.23), gadolinium uptake (P = 0.73), or the presence of vascular wall edema (P = 0.56). Conclusion Our findings indicate that there is no association between FDG vascular uptake intensity and clinical, biologic, or MRI assessment of disease activity. Previous studies using the nonvalidated NIH global activity criteria are likely biased. [source] Magnetic Resonance Imaging Outcomes From a Comprehensive Magnetic Resonance Study of Children With Fetal Alcohol Spectrum DisordersALCOHOLISM, Issue 10 2009Susan J. Astley Background:, Magnetic resonance (MR) technology offers noninvasive methods for in vivo assessment of neuroabnormalities. Methods:, A comprehensive neuropsychological/psychiatric battery, coupled with MR imaging, (MRI), MR spectroscopy (MRS), and functional MRI (fMRI) assessments, were administered to children with fetal alcohol spectrum disorders (FASD) to determine if global and/or focal abnormalities could be identified, and distinguish diagnostic subclassifications across the spectrum. The 4 study groups included: (i) fetal alcohol syndrome (FAS)/partial FAS (PFAS); (ii) static encephalopathy/alcohol exposed (SE/AE); (iii) neurobehavioral disorder/alcohol exposed (ND/AE) as diagnosed with the FASD 4-Digit Code; and (iv) healthy peers with no prenatal alcohol exposure. Presented here are the MRI assessments that were used to compare the sizes of brain regions between the 4 groups. The neuropsychological/behavioral, MRS, and fMRI outcomes are reported separately. Results:, Progressing across the 4 study groups from Controls to ND/AE to SE/AE to FAS/PFAS, the mean absolute size of the total brain, frontal lobe, caudate, putamen, hippocampus, cerebellar vermis, and corpus callosum length decreased incrementally and significantly. The FAS/PFAS group (the only group with the 4-Digit FAS facial phenotype) had disproportionately smaller frontal lobes relative to all other groups. The FAS/PFAS and SE/AE groups [the 2 groups with the most severe central nervous system (CNS) dysfunction] had disproportionately smaller caudate regions relative to the ND/AE and Control groups. The prevalence of subjects in the FAS/PFAS, SE/AE, and ND/AE groups that had 1 or more brain regions, 2 or more SDs below the mean size observed in the Control group was 78, 58, and 43%, respectively. Significant correlations were observed between size of brain regions and level of prenatal alcohol exposure, magnitude of FAS facial phenotype, and level of CNS dysfunction. Conclusions:, Magnetic resonance imaging provided further validation that ND/AE, SE/AE, and FAS/PFAS as defined by the FASD 4-Digit Code are 3 clinically distinct and increasingly more affected diagnostic subclassifications under the umbrella of FASD. Neurostructural abnormalities are present across the spectrum. MRI could importantly augment diagnosis of conditions under the umbrella of FASD, once population-based norms for structural development of the human brain are established. [source] In vivo qualitative assessments of articular cartilage in the rabbit knee with high-resolution MRI at 3 TMAGNETIC RESONANCE IN MEDICINE, Issue 3 2003Didier Laurent Abstract Proteoglycan (PG) loss and disruption of the collagen framework in cartilage are early events associated with osteoarthritis (OA). The feasibility of in vivo high-resolution MRI assessments probing both macromolecules was explored in articular cartilage of the rabbit knee. One-millimeter thick coronal images were obtained at 3 T with a 97 × 97 ,m2 pixel size. A 22% decrease in the magnetization transfer (MT) exchange rate along with an ,2-fold greater Gd(DTPA)2- -induced decrease in T1 relaxation time were measured in response to papain injection 1 day prior to the MRI session, indicative of an alteration of collagen integrity and PG depletion, respectively. A two-point method was tested as an alternative to the more time-consuming multipoint method typically used to measure T1 changes. Kinetics of Gd(DTPA)2- uptake were observed with a 10-min time resolution. The diffusive transport of Gd(DTPA)2- was characterized by a T1 decrease ,2-fold faster in papain-treated knees. These data suggest that kinetics of tracer diffusion may be used as an informative marker of PG loss, in addition to the amplitude of T1 variations. When applied to a relevant OA model, the combination of MT and Gd(DTPA)2- -MRI may help in identifying new active compounds during efficacy studies on cartilage protection. Magn Reson Med 50:541,549, 2003. © 2003 Wiley-Liss, Inc. [source] Clinical and imaging efficacy of infliximab in HLA,B27,Positive patients with magnetic resonance imaging,determined early sacroiliitis,ARTHRITIS & RHEUMATISM, Issue 4 2009Nick Barkham Objective To evaluate the efficacy of infliximab in HLA,B27,positive patients with magnetic resonance imaging (MRI),determined early sacroiliitis, using both clinical and MRI assessments. Methods Forty patients with recent-onset inflammatory back pain, as assessed by the Calin criteria, HLA,B27 positivity, clinical disease activity as measured by the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), pain and morning stiffness, and magnetic resonance imaging (MRI),determined sacroiliac joint bone edema were randomized in a double-blind manner to receive infliximab 5 mg/kg or placebo at 0, 2, 6, and 12 weeks. MRI scans were performed at baseline and 16 weeks and scored by 2 observers (blinded to both the order of the scans and to treatment group), using the Leeds scoring system. Clinical assessments included the BASDAI, the Bath Ankylosing Spondylitis Functional Index (BASFI), the Ankylosing Spondylitis Quality of Life (ASQoL) instrument, the ASsessment in Ankylosing Spondylitis International Working Group criteria (ASAS) for improvement, and markers of inflammation. Results The mean reduction in the total MRI score from week 0 to week 16 was significantly greater in infliximab-treated patients compared with placebo-treated patients (P = 0.033). On average, significantly more lesions resolved in the infliximab group (P < 0.001), while significantly more new lesions developed in the placebo group (P = 0.004). Significantly greater improvement in the infliximab group versus the placebo group was also observed for changes from week 0 to week 16 in the BASDAI (P = 0.002), BASFI (P = 0.004), and ASQoL (P = 0.007) scores. Responses according to the ASAS criteria for 40% improvement, the ASAS criteria for 20% improvement in 5 of 6 domains, and ASAS partial remission were achieved by 61%, 44%, and 56% of infliximab-treated patients, respectively. Infliximab was well tolerated, and no serious adverse events were observed. Conclusion Infliximab was an effective therapy for early sacroiliitis, providing a reduction in disease activity by week 16. This study is the first to show that infliximab is effective for reducing clinical and imaging evidence of disease activity in patients with MRI-determined early axial spondylarthritis. [source] | ||||||||||||||||||||||