Bo Xu, Presenter: Nothing to Disclose

Pascal Spincemaille PHD, Abstract Co-Author: Nothing to Disclose

Mukta Dilipkumar Agrawal MBBS, MD, Abstract Co-Author: Nothing to Disclose

Martin R. Prince MD, PhD, Abstract Co-Author: Patent agreement, General Electric Company Patent agreement, Hitachi, Ltd Patent agreement, Siemens AG Patent agreement, Toshiba Corporation Patent agreement, Koninklijke Philips Electronics NV Patent agreement, Nemoto Kyorindo Co, Ltd Patent agreement, Bayer AG Patent agreement, Lantheus Medical Imaging, Inc Patent agreement, Bracco Group Patent agreement, Covidien AG Patent agreement, Topspins, Inc

Yi Wang PhD, Abstract Co-Author: Nothing to Disclose

Dynamic liver MRI with TRACER enables retrospective selection of optimal arterial phase eliminating bolus timing artifact while showing some motion robustness.

A technique TRACER was developed which enables sub-second temporal frame rate while preserving the spatial resolution of 15 second breath hold acquisition and used in dynamic contrast enhanced 3D liver MRI.

A 3D fast spoiled gradient echo stack of spirals sequence with partial Fourier slice encoding is used for data acquisition. Consecutive stacks of spiral leaves are rotated by the golden ratio angle of 220°. Each successive dynamic frame is calculated using the previous frame as the initial guess and a single spiral leaf (including all slice encodings) is utilized for updating the current frame to get a sub-second temporal frame rate. A nonlinear reconstruction was used for updating based on MRI signal encoding equation. Experiments were conducted in three healthy volunteers and six patient volunteers after informed consent was obtained. Scans were performed on a 1.5T (GE EXCITE) scanner using an 8-channel cardiac coil. Typical scan parameters were: TR/TE=7.2/0.6ms, flip angle=12˚, BW=±125kHz, FOV=34cm, spatial resolution = 1.25×1.25×5 mm3, matrix size = 256×256×36-40. 20ml of Gd-DTPA or 10 ml Gadoxetate (Bayer, Wayne, NJ) bolus was injected at 2ml/s simultaneously with scan initiation. Contrast to noise ratio of aorta and portal vein was calculated and compared to multi-phase imaging.

TRACER provides a 48 fold temporal frame rate acceleration over multi phase acquisition with comparable spatial resolution and SNR. It eliminates the need for contrast bolus timing and provides sub-second temporal frame rate which enables the identification of the optimal arterial phase. The peak CNR between aorta and portal vein was about 70% higher than that of multi-phase images. In addition, small motions, e.g. peristalsis and shallow breathing is resolved by TRACER.

Xu, B, Spincemaille, P, Agrawal, M, Prince, M, Wang, Y, Dynamic Liver 3D MRI at Sub-Second Temporal Frame Rate: Temporal Resolution Acceleration with Constrained Evolution Reconstruction (TRACER).  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11006377.html