In vivo ¹H₂O T measurement in the human occipital lobe at 4T and 7T by Carr‐Purcell MRI: Detection of microscopic susceptibility contrast

Abstract

A high-resolution spin-echo imaging method is presented (called CP-LASER) which exploits the spin refocusing capability of an adiabatic Carr-Purcell (CP) pulse sequence to measure apparent 1 H 2 O transverse relaxation (T 2 † ) and generate contrast based on microscopic tissue susceptibility. High-resolution CP-LASER images of the human occipital lobe were acquired at four different echo times from six subjects at 4T and eight subjects at 7T to investigate the effect of magnetic field strength (B 0 ) and the CP interpulse time ( cp ) on T 2 † . Susceptibility contrast was identified and T 2 † was quantified for long cp (>10 ms) and short cp (7 ms at 4T and 6 ms at 7T) in gray matter, white matter, and cerebral spinal fluid.

Relationship of apparent myocardial T2 and oxygenation: Towards quantification of myocardial oxygen extraction fraction

“…This resulted from combined effects of interecho spacing time on the measurements of both blood and tissue T 2 . Similar findings on the T 2 change with have been reported in the gray and white matter of the brain (19). However, was not increased beyond 11.1 msec because the data acquisition window was limited owing to a relatively short RR interval (Ϸ 700 msec).…”

“…In the myocardial vascular network, a simplified model was used to describe the myocardial tissue T 2t component (18,19), with the following equation:…”

Improving MRI differentiation of gray and white matter in epileptogenic lesions based on nonlinear feedback

“…In practice, the high-field NMR spectra of the tissue samples are dominated by the broad, featureless water peak due to fast decay of the transverse magnetization under radiation damping, as well as inhomogeneous broadening in the presence of susceptibility variations. On the other hand, microscopic susceptibility gradients have been shown to change the apparent T* 2 relaxation times of water in GM and WM to different extents, leading to contrast that reflects the increased level of compartmentalized ferritin and blood volume in GM compared to WM (22). These results suggest that inherent variations in magnetic susceptibility may also contribute to resonance frequency shifts due to differences in levels of deoxyhemoglobin and cerebral blood volume between GM and WM, leading to enhanced contrast under radiation damping.…”

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