Original Research Magnetic Resonance Imaging of the Liver With Ultrashort TE (UTE) Pulse Sequences Karyn E. Chappell, BSc, 1 Nayna Patel, DCR, 2 Peter D. Gatehouse, PhD, 3 Janice Main, MD, 2 Basant K. Puri, PhD, 1 Simon D. Taylor-Robinson, MD, 2 and Graeme M. Bydder, MB, ChB 4 * Purpose: To assess the feasibility of imaging the liver in volunteers and patients with ultrashort echo time (UTE) pulse sequences. Materials and Methods: Seven normal controls as well as 12 patients with biopsy-proven generalized liver disease and three patients with focal disease were examined using pulse sequences with initial TEs of 0.08 msec followed by three later echoes, with or without frequency-based fat suppression. T 2 * values were calculated from regions of interest in the liver. Results: Good image quality was obtained in each subject. There was a highly significant difference in the mean T 2 * values between the normal controls and patients with gen- eralized liver disease (P = 0.001). T 2 * was significantly de- creased in hemochromatosis (P = 0.002) and increased in cirrhosis (P = 0.04), compared with controls. T 2 * also cor- related with functional status assessed by Child’s grade (P = 0.001). A hepatocellular carcinoma showed reduced short T 2 components in the region of thermal ablation and evidence of a subcapsular hematoma which were not ap- parent with conventional imaging. Conclusions: Imaging of the liver with UTE sequences showed good image quality and tolerance of abdominal motion. T 2 * was specifically correlated with the presence of hemochromatosis, cirrhosis, and functional grade. Imaging of short T 2 relaxation components may provide useful in- formation in disease. Key Words: magnetic resonance imaging; ultrashort TE (UTE); cirrhosis; hemochromatosis; T 2 * J. Magn. Reson. Imaging 2003;18:709 –713. © 2003 Wiley-Liss, Inc. THE CHANGES SEEN with magnetic resonance (MR) imaging in diseases of the liver such as cirrhosis are complex. In addition to changes in liver size, shape, and surface, focal differences are seen. Fibrosis may take different forms, and iron and fat deposition are common features. In cirrhosis, the disease process is usually progressive and major complications such as hepato- cellular carcinoma (HCC) are not infrequent (1,2). The MR examination typically involves the use of spin echo, fast spin echo and gradient echo sequences, in addition to early and delayed contrast enhancement with both breath-hold and non-breath-hold sequences. Gradient echo sequences are generally used in the T 1 weighted form, with a minimum echo time (TE) of about 2.1 msec for out-of-phase images at 1.5T. It is possible to image the liver with TEs 25 times shorter than this, using half excitations and radial ac- quisition from the center of k-space (3,4). Ultrashort TE (UTE) sequences of this type have several possible ad- vantages. They provide an early data point for measur- ing the T 2 * relaxation of short T 2 components before the signal level has decayed to very low levels. In addition, the higher signal level detectable at very short TEs may reduce the degree of image degradation caused by mo- tion artifact. However, with UTE imaging, slice selection is achieved in two halves separated in time; it has not been clear how well this will tolerate abdominal motion. The technique can also be used with frequency-based fat suppression but this may saturate the short T 2 com- ponents and reduce the signal detectable from them. In addition, in order to image tissues with short T 2 com- ponents separately from the majority of long T 2 compo- nents, subtraction of a later echo image from the first echo or other methods of reducing the signal from long T 2 components are necessary. There have been no pre- vious studies of imaging the liver with UTE sequences. This study was designed to assess the clinical feasibility of imaging the liver with sequences of this type. MATERIALS AND METHODS This study conformed to the guidelines outlined by the 1975 Declaration of Helsinki and permission was ob- 1 The Robert Steiner Magnetic Resonance Unit, MRC Clinical Sciences Centre, Imaging Sciences Department, Faculty of Medicine, Imperial College London, Hammersmith Hospital, London, England. 2 Division of Medicine A, Faculty of Medicine, Imperial College London, Hammersmith Hospital, London, England. 3 Cardiac MR Unit, Royal Brompton Hospital, London, England. 4 Department of Radiology, University of California San Diego, Califor- nia. *Address reprint requests to: G.M.B., Department of Radiology, Univer- sity of California San Diego, 200 West Arbor Drive, San Diego, CA 92103. E-mail: gbydder@ucsd.edu Received June 2, 2003; Accepted August 21, 2003. DOI 10.1002/jmri.10423 Published online in Wiley InterScience (www.interscience.wiley.com). JOURNAL OF MAGNETIC RESONANCE IMAGING 18:709 –713 (2003) © 2003 Wiley-Liss, Inc. 709