Timothy P. Roberts PhD, Presenter: Nothing to Disclose

Masoom Abbas Haider MD, Abstract Co-Author: Nothing to Disclose

Marshall Stephen Sussman PhD, Abstract Co-Author: Nothing to Disclose

To investigate a rigid device for separation of anterior and posterior elements of RF multicoil arrays used for abdomenal MRI in conjunction with parallel imaging acceleration factors of 2.0 - 4.0.Reduction of image ghost and additionally incurred SNR penalty will be considered.

10 healthy volunteers were imaged supine at 1.5 T using the 4-channel torsoPA coil or an 8-channel multi-coil array. Sensitivity calibration was performed during one breathhold, while axial ssFSE images were acquired during a second breathhold using acceleration factors of 2.0 and 2.6 (4 coil array) or as much as 4 (8-channel coil). Similar imaging series were repeated in the same session using a set of three rigid coil separators to physically decouple the patient's abdomen from the anterior coil elements to minimize any impact of abdominal wall motion. Phantom experiments with calibrated displacements assessed the SNR penalty.

Use of higher acceraleration factors considerably reduced scan time, and breathhold duration as well as echo train length and consequent blurring. The penalty in SNR was somewhat recovered by use of the 8-channel coil. However, without the use of the Ghostbuster, serious phase-direction wrap around ghosts introduced artifactual structure (predominatnly from the anterior chest wall into the body of the image, rendering them diagnostically useless. Using the Ghostbuster, at all accelaration factors there was complete elimination of such artufact and only a minor, yet acceptable SNR penalty associated with separation of the coil from the abdominal wall. Patients further remarked the improved comfort of the ghostbuster setup.

Without the rigid separator (the Ghostbuster), parallel imaging commonly results in ghost artifacts in abdomenal MRI. These increase in severity with increasing acceleration factors. The ghostbuster virtually eliminates such artifacts even up to acceleration factors of 4 with an 8-element coil. Drastically reduced breathhold durations, or increased anatomic coverage as well as the benefits of reduced echo train length in FSE are enabled by use of this device, which may have additional applications in kinematic and/or fetal MRI as well as at 3T.

Roberts, T, Haider, M, Sussman, M, The Ghostbuster: Rigid Separator for Multi-channel Flex-array Coils Reduces Parallel Imaging Reconstruction Artifacts in Accelerated MRI of the Abdomen.  Radiological Society of North America 2004 Scientific Assembly and Annual Meeting, November 28 - December 3, 2004 ,Chicago IL. http://archive.rsna.org/2004/4406072.html