All animal experiments were performed with the approval of the local Animal Care and Use Committee. Swine (n = 3) were anesthetized and placed in the magnet in the head-first prone position. T2W-iSSFP was used during and after needle placement. Twenty-two gauge MR-compatible needles (10–15 cm in length, MREye, Cook Medical, Bloomington, IN) were inserted through the flank into the renal collecting system of one or both kidneys while imaging using real-time T2W-iSSFP.
With the needles in place, four imaging sequences were acquired to assess their ability to visualize the inserted needle: T2-TSE, T2W-iSSFP, FS-SSFP, and T2-HASTE. T2-TSE was used as the reference for visualization as a nonreal-time imaging sequence. The images of the sequences were compared, as stated in the “Assessment” section. All of the sequences were performed using oblique axial and oblique sagittal imaging plane positions that were parallel to the needle. Phase encoding was either along the y axis or along the z axis. The specific absorption rate (SAR) of each sequence was also recorded.
With the needles in place, four imaging sequences were acquired to assess their ability to visualize the inserted needle: T2-TSE, T2W-iSSFP, FS-SSFP, and T2-HASTE. T2-TSE was used as the reference for visualization as a nonreal-time imaging sequence. The images of the sequences were compared, as stated in the “Assessment” section. All of the sequences were performed using oblique axial and oblique sagittal imaging plane positions that were parallel to the needle. Phase encoding was either along the y axis or along the z axis. The specific absorption rate (SAR) of each sequence was also recorded.