Jiang Du, Presenter: Grant, General Electric Company Research collaboration, General Electric Company

Michael Ross Peterson MD, PhD, Abstract Co-Author: Stockholder, Hologic, Inc Stockholder, QIAGEN NV

Katherine Brown, Abstract Co-Author: Nothing to Disclose

Graeme M. Bydder MBChB, Abstract Co-Author: Research grant, General Electric Company

Andrew Kahn MD, PhD, Abstract Co-Author: Nothing to Disclose

To investigate two-dimensional (2D) and 3D ultrashort echo time (UTE) magnetic resonance imaging (MRI) of carotid plaque calcification (CPC) using a clinical 3T MR scanner.

Both 2D and 3D UTE sequences with a minimum nominal TE of 8 μs were implemented on a clinical 3T GE whole-body scanner. For the 2D study, a long adiabatic inversion pulse (8.6 ms in duration) was employed to invert long T2 water and fat magnetization simultaneously in order to enhance CPC contrast. Typical imaging parameters included a FOV of 6 cm, slice thickness of 0.7 mm, TR of 300 ms, TI of 120 ms, and reconstruction matrix of 512Χ512 with a 5 minute scan time. For 3D UTE imaging, TR was 16 ms with a flip angle of 14° and a scan time of 20 minutes. Clinical T1-, T2- and PD-weighted FSE images and spoiled gradient recalled echo (SPGR) images were also obtained for comparison. In total five human carotid plaque samples were studies using a 1-inch bird-cage coil. After MR scan the specimens were studies with μCT imaging using an isotropic resolution of 90Χ90Χ90 μm3 to depict CPC. Finally the samples were subject to histologic analysis. Image signal to noise ratio (SNR) and contrast to noise ratio (CNR) were measured for CPC and soft tissues.

CPC appeared near zero signal with all conventional clinical sequences. The IR UTE sequence selectively suppressed signal from the long T2 tissue components and resulted in a mean SNR of 22.46 and positive CNR of 19.83 for CPC, which was a marked increase from that obtained with clinical spin echo or gradient echo imaging as well as regular UTE imaging. There was an excellent correlation between UTE and μCT morphological images of CPC. While clinical FSE and SPGR sequences showed near zero signal for CPC, 3D UTE showed CPC with much greater details. The histologic sections confirmed the presence of calcification.  

Direct imaging of CPC was achieved with both 2D and 3D UTE imaging. High resolution morphological images were highly correlated with results from μCT and histology.

The 2D and 3D UTE MR imaging techniques may allow non-invasive MR characterization of plaque calcification, and this may guide risk stratification and treatment of patients with carotid atherosclerosi

Du, J, Peterson, M, Brown, K, Bydder, G, Kahn, A, Two-dimensional and 3D Ultrashort TE (UTE) MR Imaging of Carotid Plaque Calcification.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11012320.html