International Journal of Radiation Oncology*Biology*Physics
Oral Scientific SessionNovel Noncontrast 4D Magnetic Resonance Imaging–Based Imaging of Tumor Infiltrating Vasculature: Improve the Accuracy of Tumor and Boost Volume Motion Characterization for Pancreas SBRT-SIB
Section snippets
Purpose/Objective(s)
Pancreatic ductal adenocarcinoma (PDA) has the worst outcome of any solid tumor. Whereas surgical resection remains the mainstay therapy, only 15% of patients present with resectable disease, because of the relationship of the primary tumor to surrounding vasculature. Stereotactic body radiation therapy (SBRT) with simultaneously integrated boost (SIB) to tumor infiltrating blood vessels has the potential to sterilize tissue around the vessels and improve resection rates. Enhancements in
Materials/Methods
Seven patients diagnosed with locally advanced PDA were recruited under an IRB protocol. A self-gated k-space sorted 4DMRI based on 3D radial sampling; gradient recalled echo readout and slab-selective excitation was implemented on a 3T scanner. Slab-selective excitation was compared to non-slab-selective excitation to understand the source of the vessel highlight. Patients also received clinical 4DCT. Two contrast-to-noise ratios (CNR), for aorta (CNRAorta) and involved vessel (CNRIV),
Results
All patients were able to complete 4DMRI acquisitions. Compared to non-slab-selective 4DMRI, the slab-selective sequence visually improved contrast of the blood vessels and reduced streaking artifacts. Quantitative analysis showed that the CNRAorta (mean ± σ) improved from 1.9 ± 2.4 to 19.7 ± 13.2 (>9-fold increase) and CNRIV improved from 1.9 ± 1.9 to 12.5 ± 9.2 (>5-fold increase) with non-contrast 4DMRI when comparing to contrast enhanced 4DCT. Correlation coefficients (mean ± σ) for the
Conclusion
A 4DMRI technique highlighting pancreatic tumor infiltrating blood vessels was prospectively evaluated for PDA patients. This non-contrast 4DMRI sequence significantly improved vessel contrast to noise ratio compared to 4DCT performed with delayed intravenous contrast. Tumor motion correlated well with involved vessels in all directions but best in the SI direction. This technique has the potential to more accurately characterize both tumor and boost volume margins for pancreas SBRT-SIB.
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Author Disclosure: W. Yang: None. Z. Fan: None. J. Pang: None. Z. Deng: None. X. Bi: None. B.A. Fraass: None. H.M. Sandler: None. N.N. Nissen: None. D. Li: None. R. Tuli: None.