Mahesh Bharath Keerthivasan1,2, Lavanya Umapathy2,3, Jean-Philippe Galons2, Diego Martin4, Ali Bilgin2,3,4, and Maria Altbach2
1Siemens Medical Solutions USA Inc, New York, NY, United States, 2Medical Imaging, University of Arizona, Tucson, AZ, United States, 3Electrical and Computer Engineering, University of Arizona, Tucson, AZ, United States, 4Biomedical Engineering, University of Arizona, Tucson, AZ, United States
1Siemens Medical Solutions USA Inc, New York, NY, United States, 2Medical Imaging, University of Arizona, Tucson, AZ, United States, 3Electrical and Computer Engineering, University of Arizona, Tucson, AZ, United States, 4Biomedical Engineering, University of Arizona, Tucson, AZ, United States
A variable refocusing flip angle radial TSE sequence
can improve slice efficiency for breath-held abdominal imaging while minimizing
T2 estimation errors and SAR.
Figure 3:
Abdominal images (3 out of 32 TEs) and corresponding T2 maps obtained from data
acquired with the VFA and constant FA RADTSE pulse sequences for subjects with
(top) hepatic hemangioma, (middle) liver metastases, and (bottom)
hepatocellular carcinoma. The lower SAR in VFA RADTSE increases slice
efficiency by 60% (11 vs 7 slices per breath hold). Note the reduced noise in
the VFA T2 map in the central part of
the liver (arrows) compared to the constant flip angle allowing for better
lesion conspicuity with the VFA scheme.
Figure 5: (A)T2 distributions show excellent separation between malignant (22 metastases, 2
HCC) and benign (8 cysts, 1 hemangioma) lesions for constant and variable
FA methods. Mean T2: 89.2±16.2ms
(malignancies) and 242.9±67.7ms (benign) for constant FA and 89.3±17.1ms (malignancies) and 219.0±58.6ms (benign) for VFA. A t-test showed
that the T2 distributions are similar between the constant and variable FA for
malignant(p=0.998) and benign lesions(p=0.435). (B)Relative contrast between malignant
lesions and adjacent liver is superior for the VFA method(p=0.013).