MO FG CAMPUS JeP2 01: 4D MRI with 3D Radial Sampling and Self Gating Based K Space Sorting: Image Quality Improvement by Slab Selective Excitation.
PURPOSE A recent 4D MRI technique based on 3D radial sampling and self gating based K space sorting has shown promising results in characterizing respiratory motion. However due to continuous acquisition and potentially drastic k space undersampling resultant images could suffer from low blood to tissue contrast and streaking artifacts. In this study 3D radial sampling with slab selective excitation (SS) was proposed in attempt to enhance blood to tissue contrast by exploiting the in flow effect and to suppress the excess signal from the peripheral structures particularly in the superior inferior direction. The feasibility of improving image quality by using this approach was investigated through a comparison with the previously developed non selective excitation (NS) approach. METHODS Two excitation approaches SS and NS were compared in 5 cancer patients (1 lung 1 liver 2 pancreas and 1 esophagus) at 3Tesla. Image artifact was assessed in all patients on a 4 point scale (0: poor; 3: excellent) Signal tonoise ratio (SNR) of the blood vessel (aorta) at the center of field of view and its nearby tissue were measured in 3 of the 5 patients (1 liver 2 pancreas) and blood to tissue contrast to noise ratio (CNR) were then determined. RESULTS Compared with NS the image quality of SS was visually improved with overall higher signal in all patients (2.6+ 0.55 vs. 3.4+ 0.55) SS showed an approximately 2 fold increase of SNR in the blood (aorta: 16.39+ 1.95 vs. 32.19+ 7.93) and slight increase in the surrounding tissue (liver/pancreas: 16.91+ 1.82 vs. 22.31+ 3.03) As a result the blood totissue CNR was dramatically higher in the SS method (1.20+ 1.20 vs. 9.87+ 6.67) CONCLUSION The proposed 3D radial sampling with slabselective excitation allows for reduced image artifact and improved blood SNR and blood to tissue CNR. The success of this technique could potentially benefit patients with cancerous tumors that have invaded the surrounding blood vessels where radiation therapy is needed to remove tumor from those regions prior to surgical resection. This work is partially supported by NIH R03CA173273; and CTSI core voucher award.
Medical physics