Four-dimensional magnetic resonance imaging using axial body area as respiratory surrogate: initial patient results.
OBJECTIVE
To evaluate the feasibility of a retrospective binning technique for 4-dimensional magnetic resonance imaging (4D-MRI) using body area (BA) as a respiratory surrogate.


METHODS
Seven patients with hepatocellular carcinoma (4 of 7) or liver metastases (3 of 7) were enrolled in an institutional review board-approved prospective study. All patients were simulated with both computed tomography (CT) and MRI to acquire 3-dimensional and 4D images for treatment planning. Multiple-slice multiple-phase cine-MR images were acquired in the axial plane for 4D-MRI reconstruction. Image acquisition time per slice was set to 10-15 seconds. Single-slice 2-dimensional cine-MR images were also acquired across the center of the tumor in orthogonal planes. Tumor motion trajectories from 4D-MRI, cine-MRI, and 4D-CT were analyzed in the superior-inferior (SI), anterior-posterior (AP), and medial-lateral (ML) directions, respectively. Their correlation coefficients (CC) and differences in tumor motion amplitude were determined. Tumor-to-liver contrast-to-noise ratio (CNR) was measured and compared between 4D-CT, 4D-MRI, and conventional T2-weighted fast spin echo MRI.


RESULTS
The means (± standard deviations) of CC comparing 4D-MRI with cine-MRI were 0.97 ± 0.03, 0.97 ± 0.02, and 0.99 ± 0.04 in SI, AP, and ML directions, respectively. The mean differences were 0.61 ± 0.17 mm, 0.32 ± 0.17 mm, and 0.14 ± 0.06 mm in SI, AP, and ML directions, respectively. The means of CC comparing 4D-MRI and 4D-CT were 0.95 ± 0.02, 0.94 ± 0.02, and 0.96 ± 0.02 in SI, AP, and ML directions, respectively. The mean differences were 0.74 ± 0.02 mm, 0.33 ± 0.13 mm, and 0.18 ± 0.07 mm in SI, AP, and ML directions, respectively. The mean tumor-to-tissue CNRs were 2.94 ± 1.51, 19.44 ± 14.63, and 39.47 ± 20.81 in 4D-CT, 4D-MRI, and T2-weighted MRI, respectively.


CONCLUSIONS
The preliminary evaluation of our 4D-MRI technique results in oncologic patients demonstrates its potential usefulness to accurately measure tumor respiratory motion with improved tumor CNR compared with 4D-CT.
Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina; School of Information Science and Engineering, Shandong University, Jinan, Shandong, China.
Juan
J
Yang
Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina.
Jing
J
Cai
School of Information Science and Engineering, Shandong University, Jinan, Shandong, China.
Hongjun
H
Wang
Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina.
Zheng
Z
Chang
Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina.
Brian G
BG
Czito
Department of Radiology, Duke University Medical Center, Durham, North Carolina.
Mustafa R
MR
Bashir
Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina. Electronic address: fangfang.yin@duke.edu.
Fang-Fang
FF
Yin
D000368:Aged; D001830:Body Surface Area; D006528:Carcinoma, Hepatocellular; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008113:Liver Neoplasms; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods; D008297:Male; D008875:Middle Aged; D009068:Movement; D012119:Respiration; D014057:Tomography, X-Ray Computed / Q000379:methods*