Isotropic reconstruction of a 4-D MRI thoracic sequence using super-resolution.
OBJECTIVE
Four-dimensional (4D) thoracic magnetic resonance imaging (MRI) sequences have been shown to successfully monitor both tumor and lungs anatomy. However, a high temporal resolution is required to avoid motion artifacts, which leads to volumes with poor spatial resolution. This article proposes to reconstruct an isotropic 4D MRI thoracic sequence with minimum modifications to the acquisition protocols. This could be an important step toward the use of 4D MRI for thoracic radiotherapy applications.


METHODS
In a postacquisition step, three orthogonal 4D anisotropic acquisitions are combined using super-resolution to reconstruct a series of isotropic volumes. A new phantom that simulates lung tumor motion is developed to evaluate the performance of the algorithm. The proposed framework is also applied to real data of a lung cancer patient.


RESULTS
Subjective and objective evaluations show clear resolution enhancement and partial volume effect diminution. The isotropic reconstruction of patient data significantly improves both the visualization and segmentation of thoracic structures.


CONCLUSIONS
The results presented here are encouraging and suggest that super-resolution can be regarded as an efficient method to improve the resolution of 4D MRI sequences. It produces an isotropic 4D sequence that would be impossible to acquire in practice. Further investigations will be required to evaluate its reproducibility in various clinical applications.
School of Chemical and Bioengineering, Nanyang Technological University, Singapore.
Eric
E
Van Reeth
Cher Heng
CH
Tan
Ivan W K
IW
Tham
Chueh Loo
CL
Poh
D000465:Algorithms; D016880:Anisotropy; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008175:Lung Neoplasms / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D010363:Pattern Recognition, Automated / Q000379:methods*; D015203:Reproducibility of Results; D055425:Respiratory-Gated Imaging Techniques / Q000379:methods*; D012680:Sensitivity and Specificity; D013382:Subtraction Technique; D013909:Thorax / Q000473:pathology; D047368:Tumor Burden
MRI phantom; interpolation; super-resolution; thoracic imaging; volume reconstruction