Development of a Mathematical Model of Renal Function for Clinical Application

This model describes the orthoiodohippurate (OIH) distribution and clearance in the renovascular system. The model is described by five compartments: the blood, left and right kidneys, bladder and the red blood cell compartment. Data for these compartments, except the RBC compartment, are collected with scintillation detectors monitoring OIH tagged with 1-131 as the radiopharmaceutical passes through each compartment. Time/ activity curves are plotted for the data and used as inputs to the model parameter estimation routine. The compartments are described by a set of first order ordinary differential equations solved using the Adam\u27s methods. For parameter estimation, an iterative predictor-corrector procedure is used. The estimated model parameters are used to calculate total and differential effective renal plasma flows which are compared to standard PAH clearance tests. A blood-to-urine flow index, defined in this research using these parameters, and a cortex-to-medulla transit is also used to evaluate various renal diseases surgically induced in animal models. The predicted effective renal plasma flows correlate well with the PAH clearances for both normal and abnormal conditions and the blood-to-urine flow index is particularly useful in differentiating between ureteral obstruction and renal vein occlusion

Diffusion Tensor Imaging Findings in Pediatric Patients with Mild Traumatic Brain Injury

Approximately 14% of school age children with sports-related concussions (SRC) remain symptomatic 3 months after injury. Previous studies have used diffusion tensor imaging (DTI) to detect white matter tract changes in regions of interest in symptomatic patients; however data in the pediatric population remains limited. This study was undertaken to determine whether DTI metrics can provide valuable information in pediatric mTBI patients with persistent symptoms

Novel Pattern of Iron Deposition in the Fascicula Nigrale in Patients with Parkinson’s Disease: A Pilot Study

Background and Purpose. To determine whether the pattern of iron deposition in the fascicula nigrale in patients with Parkinson’s disease would be different from age-matched controls by utilizing quantitative susceptibility mapping to measure susceptibility change. Methods. MRIs of the brain were obtained from 34 subjects, 18 with Parkinson’s disease and 16 age- and gender-matched controls. Regions of interest were drawn around the fascicula nigrale and substantia nigra using SWI mapping software by blinded investigators. Statistical analyses were performed to determine susceptibility patterns of both of these regions. Results. Measurements showed significantly increased susceptibility in the substantia nigra in Parkinson’s patients and an increased rostral-caudal deposition of iron in the fascicula nigrale in all subjects. This trend was exaggerated with significant correlation noted with increasing age in the Parkinson group. Conclusion. The pattern of an exaggerated iron deposition gradient of the fascicula nigrale in the Parkinson group could represent underlying tract dysfunction. Significant correlation of increasing iron deposition with increasing age may be a cumulative effect, possibly related to disease duration

The clinical utility of proton magnetic resonance spectroscopy in traumatic brain injury: recommendations from the ENIGMA MRS working group

Proton ( H) magnetic resonance spectroscopy provides a non-invasive and quantitative measure of brain metabolites. Traumatic brain injury impacts cerebral metabolism and a number of research groups have successfully used this technique as a biomarker of injury and/or outcome in both pediatric and adult TBI populations. However, this technique is underutilized, with studies being performed primarily at centers with access to MR research support. In this paper we present a technical introduction to the acquisition and analysis of in vivo H magnetic resonance spectroscopy and review H magnetic resonance spectroscopy findings in different injury populations. In addition, we propose a basic H magnetic resonance spectroscopy data acquisition scheme (Supplemental Information) that can be added to any imaging protocol, regardless of clinical magnetic resonance platform. We outline a number of considerations for study design as a way of encouraging the use of H magnetic resonance spectroscopy in the study of traumatic brain injury, as well as recommendations to improve data harmonization across groups already using this technique