Direct imaging of white matter ultrashort T2∗ components at 7 Tesla.
Magn Reson Imaging
; 86: 107-117, 2022 02.
Article
in En
| MEDLINE
| ID: mdl-34906631
ABSTRACT
PURPOSE:
To demonstrate direct imaging of the white matter ultrashort T2∗ components at 7 Tesla using inversion recovery (IR)-enhanced ultrashort echo time (UTE) MRI. To investigate its characteristics, potentials and limitations, and to establish a clinical protocol. MATERIAL ANDMETHODS:
The IR UTE technique suppresses long T2∗ signals within white matter by using adiabatic inversion in combination with dual-echo difference imaging. Artifacts arising at 7 T from long T2∗ scalp fat components were reduced by frequency shifting the IR pulse such that those frequencies were inverted likewise. For 8 healthy volunteers, the T2∗ relaxation times of white matter were then quantified. In 20 healthy volunteers, the UTE difference and fraction contrast were evaluated. Finally, in 6 patients with multiple sclerosis (MS), the performance of the technique was assessed.RESULTS:
A frequency shift of -1.2 ppm of the IR pulse (i.e. towards the fat frequency) provided a good suppression of artifacts. With this, an ultrashort compartment of (68 ± 6) % with a T2∗ time of (147 ± 58) µs was quantified with a chemical shift of (-3.6 ± 0.5) ppm from water. Within healthy volunteers' white matter, a stable ultrashort T2∗ fraction contrast was calculated. For the MS patients, a significant fraction reduction in the identified lesions as well as in the normal-appearing white matter was observed.CONCLUSIONS:
The quantification results indicate that the observed ultrashort components arise primarily from myelin tissue. Direct IR UTE imaging of the white matter ultrashort T2∗ components is thus feasible at 7 T with high quantitative inter-subject repeatability and good detection of signal loss in MS.Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
White Matter
/
Multiple Sclerosis
Type of study:
Guideline
/
Prognostic_studies
Limits:
Humans
Language:
En
Journal:
Magn Reson Imaging
Year:
2022
Document type:
Article