Stretchable coil arrays: Application to knee imaging under varying flexion angles

Abstract

To fit high-density receiver arrays for MRI closely around individual target anatomies, there is a need to provide a high degree of geometric adjustability with ease of handling and patient comfort. In this work, this is accomplished by the construction of a coil array that is stretchable such that it automatically conforms to a given anatomy's shape and size. Stretchability is implemented by creating the coil conductors from braided wire mounted on an elastic textile substrate. The signal-to-noise ratio yield of such coils is measured by MRI experiments at 3 T, and the signal-to-noise ratio effect of coil stretching is investigated with and without adjustment of the matching between each coil and the respective preamplifier. Four-channel and eight-channel arrays of stretchable receiver coils are evaluated in phantoms as well as for in vivo imaging of the human knee. Exploiting stretchability, it is demonstrated that the knee can be imaged under varying flexion angles up to 60°while maintaining closely coupled array detection, high signal-to-noise ratio, and uniform coverage of the entire joint. Magn Reson Med 67:872-879, 2012. V C 2011 Wiley Periodicals, Inc.

Size‐adaptable 13‐channel receive array for brain MRI in human neonates at 3 T

“…The obtained levels of preamplifier decoupling compensated the significant overall mutual coupling that existed in this array, as previously found . This result was evidenced by the noise correlation obtained from the zero‐excitation scans performed with all phantoms.…”

“…The shielding of the output circuits (output PCB, RF connectors, cable traps) and the routing of the output coaxial cables can be improved to reduce possible destructive crosstalk among elements, which arises when the amplified magnetic resonance signal is present. The lack of uniformity of the SNR patterns, mainly in the sensitivity regions of Channels 1 and 4, could be caused by this unwanted coupling, considering that the noise correlation values are similar to those obtained with the commercial coil, and to other proposed adaptable arrays that do not preserve the critical overlapping through all the range …”

Patient Perception of Lower Limb Non-Contrast Magnetic Resonance Angiography and Digital Subtraction Angiography in Diabetic Patients with Peripheral Arterial Disease

“…Next, two patients experienced pain from coil pressure in their symptomatic extremities. Ongoing improvements in receiver coil design, such as weight reduction and improvements in the flexibility and shape, may reduce coil-related pressure [46,47]. Issues of claustrophobia (n=1) and large body habitus precluding positioning at the isocenter of the magnet bore (n=1) may be mitigated with wide-bore systems that are commercially available but were not available at our institution, and which have been demonstrated to decrease patient claustrophobia [48,49].…”

MRI of weight bearing and movement

“…Flexible knee coils have been developed, tested and shown, in a very few number of subjects, to have similar results to static data while reporting high SNR values and homogenous coverage 69, 70 . A high-resolution steady-state free precession (SSFP) pulse sequence was applied to track bone motion with real-time MR imaging.…”