Abstract
PurposeImaging the carotid arteries at 7T ideally requires a flexible multichannel array that allows B1‐shimming and conforms to different neck sizes. The major challenge is to minimize coupling between closely spaced coils and to make the coupling relatively insensitive to loading conditions.MethodsWe have designed a five‐channel flexible transceive array composed of shielded‐coaxial‐cable coils placed on the anterior part of the neck and conforming to the anatomy. In vivo imaging of the carotid arteries in three subjects has been performed.ResultsThe measured noise correlation matrices show the decoupling level between the individual elements to be −12.5 dB and better. Anatomical localizer imaging of the carotids shows both carotids in every subject well visualized after B1‐shimming. In vivo black‐blood, carotid images were acquired with very high in‐plane spatial resolution (0.25 × 0.25 mm2) with clear depiction of the vessel walls.ConclusionsThe flexibility of the proposed coil has been demonstrated by imaging subjects with different neck circumferences. To the best of our knowledge, the in‐plane resolution of 0.25 × 0.25 mm2 is the highest reported at 7T.
Highlights
There is a high level of interest in using noninvasive MRI for vascular imaging in atherosclerosis, which is a systemic disease affecting the intermediate- and large-sized arteries.[1]
High-resolution imaging of the carotid arteries can identify regions of stenosis and abnormal arterial blood flow, and information on the components of a particular plaque, such as lipids within the core, the nature of the fibrous cap, and any intraplaque hemorrhage can be obtained if the spatial resolution, signal-to-noise (SNR), and contrast-to-noise (CNR) are sufficiently high
The use of very high field (7 T and above) MRI scanners would appear to be promising for carotid artery vessel wall imaging.[3]
Summary
There is a high level of interest in using noninvasive MRI for vascular imaging in atherosclerosis, which is a systemic disease affecting the intermediate- and large-sized arteries.[1]. This means that the coil arrays must be very flexible, and the interelement decoupling must be relatively insensitive to changes in their geometry (i.e., bending and flexing) as well as to the degree of loading in terms of being close to a smaller or larger degree of lipid or muscle To address these issues, in this work we have designed a flexible fiveelement neck array with each element consisting of a shieldedcoaxial-cable (SCC) coil.[8] The SCC coil is an element that can be constructed from very flexible thin coaxial-cable, does not require distributed lumped element capacitance within the structure, and has been shown to have a high degree of intrinsic decoupling between elements as well as a lower dependence of tuning and decoupling with respect to geometric deformation than for conventional surface coils.[8] Here, we assess the use of such an array in obtaining very high spatial resolution (0.25 × 0.25 mm[2] in-plane) black-blood images of the carotid arteries in healthy volunteers with different neck sizes
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