Project Summary/Abstract The widespread availability of portable Magnetic Resonance Imaging (MRI) scanners that can be transported to the bedside could have a tremendous impact for critical care and general clinical care in low- resource settings. To achieve truly portable, point-of-care operation, a low magnetic field strength (<0.1 T) is considered a prerequisite for both size requirements and safety considerations. However, the main limitation of low-field MRI is the associated low signal-to-noise (SNR) ratio. The low SNR of these systems results in significantly inferior image quality compared to conventional MRI. While high SNR is not always necessary to detect pathology, there may be a high risk of missed findings and misdiagnosis. This is a significant issue that currently defrays the use of low-field MRI and could ultimately limit the widescale adoption and scale-up of portable accessible MRI technology. One non-invasive method for improving the sensitivity of the MR measurement, is to maximize the receiver coil sensitivity. Our proposal attempts to achieve this with stretchable receiver caps for brain imaging. The stretchable coils will adapt to each subject to provide the highest filling factor for the coil and attempt to achieve body-noise dominance. Instead of using a lossy stretchable conductor, we will use flexible, strategically draped litz wire on a stretchable cap to construct the single channel receiver coil. The inductance of the coil will change with each subject due to the change-able diameter and shape. Therefore, we will implement an external tuning and matching box for “autotuning” the coil. The autotuning system will make use of a compact PC-controlled vector network analyzer (VNA) to monitor the S-parameters of the coil and output appropriate voltages to voltage-controlled capacitors (varactor diodes) for adjustable tuning/matching. Our end goal is to create the optimal brain imaging coil for each individual subject (through adapting the shape and tuning/matching) with the ultimate goal of improving portable MRI image quality and clinical utility.