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MRI Biomarkers (mri + biomarker)
Selected AbstractsStructural MRI biomarkers for preclinical and mild Alzheimer's disease,HUMAN BRAIN MAPPING, Issue 10 2009Christine Fennema-Notestine Abstract Noninvasive MRI biomarkers for Alzheimer's disease (AD) may enable earlier clinical diagnosis and the monitoring of therapeutic effectiveness. To assess potential neuroimaging biomarkers, the Alzheimer's Disease Neuroimaging Initiative is following normal controls (NC) and individuals with mild cognitive impairment (MCI) or AD. We applied high-throughput image analyses procedures to these data to demonstrate the feasibility of detecting subtle structural changes in prodromal AD. Raw DICOM scans (139 NC, 175 MCI, and 84 AD) were downloaded for analysis. Volumetric segmentation and cortical surface reconstruction produced continuous cortical surface maps and region-of-interest (ROI) measures. The MCI cohort was subdivided into single- (SMCI) and multiple-domain MCI (MMCI) based on neuropsychological performance. Repeated measures analyses of covariance were used to examine group and hemispheric effects while controlling for age, sex, and, for volumetric measures, intracranial vault. ROI analyses showed group differences for ventricular, temporal, posterior and rostral anterior cingulate, posterior parietal, and frontal regions. SMCI and NC differed within temporal, rostral posterior cingulate, inferior parietal, precuneus, and caudal midfrontal regions. With MMCI and AD, greater differences were evident in these regions and additional frontal and retrosplenial cortices; evidence for non-AD pathology in MMCI also was suggested. Mesial temporal right-dominant asymmetries were evident and did not interact with diagnosis. Our findings demonstrate that high-throughput methods provide numerous measures to detect subtle effects of prodromal AD, suggesting early and later stages of the preclinical state in this cross-sectional sample. These methods will enable a more complete longitudinal characterization and allow us to identify changes that are predictive of conversion to AD. Hum Brain Mapp 2009. © 2009 Wiley-Liss, Inc. [source] Evaluation of a magnetic resonance biomarker of osteoarthritis disease progression: doxycycline slows tibial cartilage loss in the Dunkin Hartley guinea pigINTERNATIONAL JOURNAL OF EXPERIMENTAL PATHOLOGY, Issue 2 2009Jonathan Bowyer Summary The objective was to assess the effect of doxycycline treatment on a magnetic resonance imaging (MRI) biomarker of cartilage volume loss, and on matrix metalloproteinase (MMP) activity in a guinea pig osteoarthritis model. Guinea pigs (9 months old) were dosed with vehicle or doxycycline, 0.6, 3.0 mg/kg/day for 66 days. Fat-suppressed 3D gradient-echo MRI of the left knee was acquired pre- and post dosing. Change in medial tibial plateau (MTP) cartilage volume (MT.VC) was determined using image analysis. At termination, MTP cartilage was removed from knees and proteolytic MMP activity determined using a fluorescent peptide substrate assay. Vehicle-treated animals lost 20.5% (95% CI mean 25.6,15.1) MT.VC. The doxycycline (0.6 mg/kg/day) group lost 8.6% (P < 0.05, 95% CI 20.6 to ,5.3) whilst the 3.0 mg/kg/day group lost 10.0% (P < 0.05, 95% CI 13.9,6.0%). Endogenous levels of active MMPs were below limits of detection in all samples. However, doxycycline treatment ablated amino phenyl mercuric acid activated MMP-13 and MMP-8 levels, reduced MMP-9 levels by 65% and MMP-1 levels by 24%. Doxycycline treatment resulted in partial protection from MT.VC loss and was associated with complete reduction in MMP-13 and MMP-8, and partial reduction in MMP-9 activity. These data imply a role of MMPs in cartilage degeneration but incomplete protection suggests that additional doxycycline insensitive mechanisms are important in this model. The protective effect of doxycycline correlates with the clinical finding of lessened joint space narrowing, strengthens the utility of this animal model in identifying disease-modifying osteoarthritic drugs and supports the use of MRI biomarkers of cartilage loss. [source] Value of quantitative MRI biomarkers (Evans' index, aqueductal flow rate, and apparent diffusion coefficient) in idiopathic normal pressure hydrocephalusJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2009FRCR, Samuel E.S. Ng MBBS Abstract Purpose To define the value of Evans' index (EI), aqueductal flow rate (FR), and apparent diffusion coefficient (ADC) in the diagnosis of normal pressure hydrocephalus (NPH) and to assess the ability of these markers preoperatively to predict shunt response. To shed some light as to the mechanisms responsible for the symptoms of NPH. Materials and Methods Preoperative EI, FR, and ADC readings in nine cases of clinically diagnosed NPH were compared with those of age- and gender-matched controls. Similar pre- and postoperative readings of responders and nonresponders were subsequently compared. Results Compared with the controls, all measurements were statistically significant except for peak systolic flow rate (pSfr), which was near statistical significance. Comparison of pre- and postoperative readings of responders and nonresponders revealed a decrease in ADC in all responders (P = 0.032). Subdural hemorrhage was found in all nonresponders (P = 0.012). Conclusion For patients presenting with signs and symptoms of NPH, readings on MRI greater than 0.3, 10 mL/min, ,9.0 mL/min, and 10.65 × 10,4 mm2/s for EI, peak diastolic flow rate (pDfr), pSfr, and ADC, respectively, add further weight to the diagnosis. The strong correlation between shunt response and ADC decline support our hypothesis that water accumulation in the cerebrum is the major cause for the symptoms of NPH. The presence of subdural hemorrhage in all nonresponders raises suspicion of decreased compliance as the other major cause. J. Magn. Reson. Imaging 2009;30:708,715. © 2009 Wiley-Liss, Inc. [source] |