Magnetic Resonance Imaging of Differential Compartmental
نویسندگان
چکیده
20 Activity in horizontal rectus extraocular muscles (EOMs) was investigated by magnetic 21 resonance imaging (MRI) of humans during asymmetrical convergence to a monocularly aligned 22 target at 15 cm distance, or monocular fixation of afocal targets placed over a wide range of 23 conjugate abduction through adduction. Cross sections and posterior partial volumes (PPV) of 24 EOMs were determined from quasi-coronal image planes, and were separately analyzed in the 25 inferior vs. superior compartments, defined by lines bisecting their maximum vertical 26 dimensions. Both inferior and superior compartments of medial (MR) and lateral rectus (LR) 27 exhibited contractile changes in PPV and maximum cross section for both asymmetric 28 convergence and a comparable range of conjugate adduction. Both LR compartments, and the 29 inferior MR compartment, exhibited similar decreases in contractility correlating with relaxation 30 during both convergence and conjugate adduction. In contrast, the superior MR compartment 31 exhibited roughly three times the contractility in conjugate adduction as in similar magnitude 32 convergence. In the aligned eye that did not move during convergence, summed contractility in 33 all compartments of MR and LR exhibited co-relaxation consistent with published EOM force 34 measurements in this paradigm (Miller et al. 2002; Miller et al. 2011). The superior MR 35 compartment also exhibited significantly greater contractility than the other compartments over 36 the maximum achievable horizontal globe rotation from abduction to adduction. These findings 37 suggest that the superior MR compartment is controlled differentially from the inferior 38 compartment, and suggest that its activity is reduced during convergence as a component of 39 generally altered extraocular mechanics. 40
منابع مشابه
Functional morphometry demonstrates extraocular muscle compartmental contraction during vertical gaze changes.
Anatomical studies demonstrate selective compartmental innervation of most human extraocular muscles (EOMs), suggesting the potential for differential compartmental control. This was supported by magnetic resonance imaging (MRI) demonstrating differential lateral rectus (LR) compartmental contraction during ocular counterrolling, differential medial rectus (MR) compartmental contraction during ...
متن کاملUse of Magnetic Resonance Imaging in Food Quality Control: A Review
Modern challenges of food science require a new understanding of the determinants of food quality and safety. Application of advanced imaging modalities such as magnetic resonance imaging (MRI) has seen impressive successes and fast growth over the past decade. Since MRI does not have any harmful ionizing radiation, it can be considered as a magnificent tool for the quality control of food prod...
متن کاملStatic Coil Design Considerations for the Magnetic Resonance Imaging
One of the main challenges in developing magnetic resonance imaging (MRI) systems is to create a static coil that needs to generate magnetic field density along with the characteristics of optimal homogeneity and magnitude size. To do this, two N42 Block PMs are used and the iron core is designed and optimized in accordance with the dimensions of PM pieces using ANSYS Maxwell software. Then, al...
متن کاملANALYTICAL STUDY OF EFFECT OF BILAYER INORGANIC AND ORGANIC COATING AROUND THE IRON OXIDE NANOPARTICLES ON MAGNETIC RESONANCE IMAGING CONTRAST
Background & Aims: In recent years, iron oxide nanoparticles have been used in contrast-enhanced magnetic resonance imaging for diagnosing a wide range of diseases. In order to provide biocompatibility and prevent the toxicity of the nanoparticles, using organic or inorganic coating around these nanoparticles is important for their application. The aim of this study is to investigate the effect...
متن کاملApplication of Magnetic Resonance Imaging (MRI) as a safe & Application of Magnetic Resonance Imaging (MRI) as a safe & non-destructive method for monitoring of fruit & vegetable in postharvest period
To investigate and control quality, one must be able to measure quality-related attributes. Quality of produce encompasses sensory attributes, nutritive values, chemical constituents, mechanical properties, functional properties and defects. MRI has great potential for evaluating the quality of fruits and vegetables. The equipment now available is not feasible for routine quality testing. The ...
متن کامل