The signal-to-noise ratio (SNR) is a major obstacle to system noise, and (b) closer coupling between the sample and achieving increased resolution in magnetic resonance microscopy the coil for improved receiver efficiency. These design constraints (MRM). The SNR considerations for MRM are presented, with particuresult in radiofrequency (rf) coils with geometries significantly lar attention to the role of judicious receiver coil design in maximizing different from those used for clinical MRI. The goals of this sensitivity and limiting noise contributions both from the sample and article are to present an overview of important concepts involved the coil. We present a number of different coil configurations that have in the design of coils for MR microscopy and to demonstrate the been optimized for particular applications of MRM in the biological utility of particular coil geometries with typical applications.
sciences. An overview of the literature regarding derivations of the SNR for birdcage-configuration volume coils, inductively coupled surface coils, and surgically implanted coils is presented in a unified
II. THEORY fashion. Microscopy coils designed to reduce the total volume of
To understand the relationship between the physical dimensions excitation, thus coupling more closely to a given region of interest, of a given coil and the SNR available to the receiver chain, we are discussed. The volume coil is presented in terms of its application present a brief summary of the literature in regards to several to lung imaging in small animals at 2 T and imaging of stroke at 7 coil geometries of interest: birdcage resonators, surface coils, and T. The performance of traditional surface coils is demonstrated by implanted coils. As a basis for analysis, we use the principle application to spinal cord imaging in the rat. Finally, implanted coils of reciprocity [3], which states that assuming a uniform field are examined, as used in studies of the carotid arteries.