Three-dimensional quantitative T1 and T2 mapping of the carotid artery: Sequence design and in vivo feasibility.
OBJECTIVE
A novel three-dimensional (3D) T1 and T2 mapping protocol for the carotid artery is presented.


METHODS
A 3D black-blood imaging sequence was adapted allowing carotid T1 and T2 mapping using multiple flip angles and echo time (TE) preparation times. B1 mapping was performed to correct for spatially varying deviations from the nominal flip angle. The protocol was optimized using simulations and phantom experiments. In vivo scans were performed on six healthy volunteers in two sessions, and in a patient with advanced atherosclerosis. Compensation for patient motion was achieved by 3D registration of the inter/intrasession scans. Subsequently, T1 and T2 maps were obtained by maximum likelihood estimation.


RESULTS
Simulations and phantom experiments showed that the bias in T1 and T2 estimation was < 10% within the range of physiological values. In vivo T1 and T2 values for carotid vessel wall were 844 ± 96 and 39 ± 5 ms, with good repeatability across scans. Patient data revealed altered T1 and T2 values in regions of atherosclerotic plaque.


CONCLUSIONS
The 3D T1 and T2 mapping of the carotid artery is feasible using variable flip angle and variable TE preparation acquisitions. We foresee application of this technique for plaque characterization and monitoring plaque progression in atherosclerotic patients.
Department of Radiology, Academic Medical Center, Amsterdam, the Netherlands.
Bram F
BF
Coolen
Biomedical Imaging Group Rotterdam, Depts. of Radiology and Medical Informatics, Erasmus Medical Center, Rotterdam, the Netherlands.|Quantitative Imaging Group, Department of Imaging Physics, Delft University of Technology, Delft, The Netherlands.
Dirk H J
DH
Poot
Department of Neurology, Academic Medical Center, Amsterdam, the Netherlands.
Madieke I
MI
Liem
Department of Vascular Medicine, Academic Medical Center, Amsterdam, the Netherlands.
Loek P
LP
Smits
Department of Radiology, Division of Image Processing, Leiden University Medical Center, Leiden, The Netherlands.
Shan
S
Gao
Department of Radiology, Erasmus Medical Center, Rotterdam, the Netherlands.
Gyula
G
Kotek
Biomedical Imaging Group Rotterdam, Depts. of Radiology and Medical Informatics, Erasmus Medical Center, Rotterdam, the Netherlands.
Stefan
S
Klein
Department of Radiology, Academic Medical Center, Amsterdam, the Netherlands.
Aart J
AJ
Nederveen
D000328:Adult; D000369:Aged, 80 and over; D002339:Carotid Arteries / Q000033:anatomy & histology*; D002340:Carotid Artery Diseases / Q000473:pathology; D003198:Computer Simulation; D005240:Feasibility Studies; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D019047:Phantoms, Imaging; D055815:Young Adult
T1 mapping; T2 mapping; atherosclerosis; carotid artery; quantitative imaging; vessel wall imaging