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

Abstract

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 *.

High‐resolution MRI of mummified tissues using advanced short‐T2 methodology and hardware

“…The hand sample did not load the coil, as reported in Ref. 18 and the foot sample loaded it very slightly, indicating coil-dominated noise. The bandwidth obtained at −3 dB from an S 21 measurement was 0.67 MHz, corresponding to a Q of 190.…”

“…Each data set has been assigned a scan number that will be used to reference the respective scan in the remainder of this paper. The target T 2 used to determine the effect of the HYFI parameter A was 200 µs for all scans, which was based on previous findings 18 . In addition to the imaging data, FID signals without spatial selection were recorded for all sample/coil configurations to enable decay component analysis.…”

“…To achieve full‐volume coverage with useful SNR for the main image scans of the limb samples, a solenoid coil was constructed. This coil had seven windings of copper tape spread over 250 mm of a 300 mmlong PMMA tube of 120 mm outer diameter and was designed based on the coil presented in Ref 18 . Each copper winding was split in two places at opposite sides of the coil, and the gap between each half‐winding was connected alternately with a 6.8 pF or 8.2 pF capacitor.…”

“…This coil had seven windings of copper tape spread over 250 mm of a 300 mmlong PMMA tube of 120 mm outer diameter and was designed based on the coil presented in Ref. 18 Each copper winding was split in two places at opposite sides of the coil, and the gap between each half-winding was connected alternately with a 6.8 pF or 8.2 pF capacitor. The end of the final winding was connected to the start of the first by an additional segment of copper tape and a split capacitor, ie two 14.1 pF capacitors with a ground between them to balance the circuit.…”

In vivo MRI with Concurrent Excitation and Acquisition using Automated Active Analog Cancellation

“…Six plastic tubes filled with contrast agent RESOVIST (Bayer Schering Pharma AG, Leverkusen, Germany) corresponding to Fe concentrations of 0.02, 0.029, 0.038, 0.056, 0.071, and 0.1 M were imaged. For the UTE acquisition, the following parameters were used: TE = 70 µs; TR = 2.6 ms; flip angle = 2°; averages = 10; FOV = 320 mm; BW = 1488 Hz/px; radial spokes = 64000, number of points per spoke = 160; total scan time = 1664 s. With CEA, the following parameters were used: RF bandwidth = 128 kHz; TR = 2.6 ms; effective flip angle = 0.12°; averages = 10; FOV = 320 mm; acquisition time = 2.1 ms; radial spokes = 64000, number of points per spoke = 320; total scan time = 1664 s. Signal-to-noise ratio (SNR) values were calculated and scaled to account for the differences in imaging parameters 42 . A UTE pulse sequence with the same parameters was also used to measure T 2 * of the phantoms for TE = {70, 100, 120, 140, 160, 180, 200, 500} µs.…”