Purpose: 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.
Methods: 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.
Results: 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.
Conclusion: 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 *.
Keywords: PETRA; SPI; SPRITE; UTE; ancient human mummy; dehydrated tissue; relaxation time; short T2*; solenoid coil.
© 2015 Wiley Periodicals, Inc.