Dephased FLAPS for improved visualization of susceptibility-shifted passive devices for real-time interventional MRI.
Recently, balanced steady-state free precession (SSFP) magnetic resonance imaging at small flip angles (i.e. FLAPS imaging) has been shown to preferentially enhance the visibility of spins residing near susceptibility-shifted media by exploiting the unique spectral response of SSFP signals. Nevertheless, the use of FLAPS imaging to visualize passive, susceptibility-shifted devices within thick slices is complicated by partial volume effects that reduce the conspicuity of the devices. In this work, dephased FLAPS (dFLAPS), a variation of the FLAPS method with dephasing gradients applied in the slice direction, is presented as a method for improving the contrast of susceptibility-shifted interventional devices in thick-slice magnetic resonance images by suppressing signal from on-resonant spins. In comparison to FLAPS imaging, results demonstrate that dFLAPS imaging of thick, projection-like slices improves the contrast of susceptibility-shifted devices relative to background signal with no increase in acquisition time.
Department of Radiology, Northwestern University, Suite 700, 448 E. Ontario St, Chicago, IL 60611, USA. i-koktzoglou@northwester.edu
Ioannis
I
Koktzoglou
Debiao
D
Li
Rohan
R
Dharmakumar
D000818:Animals; D001013:Aorta, Thoracic / Q000473:pathology; D001707:Biopsy, Needle; D002417:Cattle; D004574:Electromagnetic Fields; D006801:Humans; D008099:Liver / Q000473:pathology; D053783:Magnetic Resonance Imaging, Interventional / Q000379:methods*; D015233:Models, Statistical; D008962:Models, Theoretical; D009206:Myocardium / Q000473:pathology; D019047:Phantoms, Imaging; D015607:Stents; D013997:Time Factors; D051598:Whole Body Imaging