Comparison of ultrashort echo time sequences for MRI of an ancient mummified human hand.

Abstract

To compare the three different short-echo time (TE) pulse sequences ultrashort echo time (UTE), point-wise encoding time reduction with radial acquisition (PETRA), and single point imaging (SPI) for MRI of ancient remains. MRI of mummies is challenging due to the extremely low water content and the very short transverse relaxation times T2 *. To overcome the signal loss associated with the short T2 *, three pulse sequences with very short TEs were compared. MR images of an ancient mummified human hand were acquired at field strengths of 1.5 Tesla (T) and 3T using home-made solenoid Tx/Rx radiofrequency (RF) coils. In all MR images, tissues could be differentiated and anatomical structures such as bones and tendons were clearly identified. Skin with embalming resin was hyperintense in MRI, whereas it appeared iso-intense in computed tomography. PETRA has the highest signal to noise ratio. With UTE, short scan times and a homogeneous RF excitation can be achieved, and blurring is less pronounced than with PETRA. SPI shows no blurring artifacts; however, it requires long scan times. This work provided an initial analysis for the optimization of imaging protocols for paleoradiology studies with MRI, and, ultimately, for MRI of tissue with extremely short T2 *.