Ultra-High-Resolution Skin Imaging at 7 T with Motion Correction and Fat/Water Separation Presentation: 1:30pm # Electrical Engineering, 3 Radiology Stanford University 2 Applied Science Laboratory GE Healthcare 4 Electrical Engineering & Computer Sciences UC Berkeley 5 Palo Alto Medical Foundation J.K. Barral 1 M.M. Khalighi 2 R.D. Watkins 3 M. Lustig 1,4 B.S. Hu 1,5 D.G. Nishimura 1
# 3248Skin Imaging - J.K. Barral et al.2/16 In a Nutshell High-resolution skin imaging requires: (1) a short TE (dermis has short T2s) GRE (2) fat/water separation (hypodermis is fat) IDEAL (3) motion correction navigators Our sequence satisfies these requirements. We imaged the calves of healthy volunteers at 1.5 T and 7 T and demonstrate up to 100 µm isotropic resolution.
# 3248Skin Imaging - J.K. Barral et al.3/16 The Skin Epidermis ~ 0.1 m m Dermis ~ 1 mm Hypodermis (fat) ~ 10 mm SURFACE COIL MUSCLE
# 3248Skin Imaging - J.K. Barral et al.4/16 Previous 3 T and 7 T Barral, ISMRM 2009, p.1993 Laistler, ISMRM 2009, p. 828 Maderwald, ISMRM 2008, p Maderwald, ISMRM 2009, p Short TE: GRE Fat/water separation: Saturation Dixon/IDEAL methods Chemical shift used for segmentation Skin squeezed Methods limited to specific body areas Immobilization to prevent motion: Velcro® fastener Weight of subject Aircast® plastic boot Image realignment before averaging Intrascan motion not corrected Resolution limited or contrast agent used
# 3248Skin Imaging - J.K. Barral et al.5/16 Hardware 0.5 inch Ø 1 inch Ø T 1.5 T and 7 T Gradients: –40 mT/m –150 mT/m/ms
# 3248Skin Imaging - J.K. Barral et al.6/16 Pulse Sequence Song, MRM 41: , Barral, MRM 63: , 2010 Navigator Spoiler Fractional echo readout Short TR (~ ms)
# 3248Skin Imaging - J.K. Barral et al.7/16 Pulse Sequence Navigator interleaved (SNR; gradient duty cycle) Three TEs interleaved (fat/water separation)
# 3248Skin Imaging - J.K. Barral et al.8/16 Reconstruction MOTIONCORRECTIONMOTIONCORRECTION Song, MRM 41: , 1999 Barral, Motion Workshop 2010, p T, slice 8/16 Echo 1 Echo 2 Echo 3 Echo 1 Echo 2 Echo 3 IDEALIDEAL Fat Water Reeder, MRM 54: , 2005
# 3248Skin Imaging - J.K. Barral et al.9/16 Experiment Parameters Field strength [T]1.57 TR [ms]2850 TE [ms]56 FA [°]20 BW [kHz]±32 FOV [cm 3 ]6x3x1.64x1.5x0.8 Matrix size512x256x16400x150x80 Scan time [min:sec]5:4430:00 Resolution [µm 3 ] 117x117x x100x100 Voxel volume [nL]141
# 3248Skin Imaging - J.K. Barral et al.10/16 Results at 1.5 T L/R A/P S/I Motion estimates
# 3248Skin Imaging - J.K. Barral et al.11/16 Results at 1.5 T FatMotion-corrected fat WaterMotion-corrected water Slice 13/16, FOV cropped to 5.3 x 2.3 cm 2 Epidermis Dermis Hypodermis Muscle 5 mm
# 3248Skin Imaging - J.K. Barral et al.12/16 Results at 1.5 T FatMotion-corrected fat WaterMotion-corrected water 16 slices, FOV cropped to 5.3 x 2.3 cm 2
# 3248Skin Imaging - J.K. Barral et al.13/16 Results at 7 T Motion estimates L/R A/P S/I
# 3248Skin Imaging - J.K. Barral et al.14/16 Results at 7 T Axial Sagittal Water Coronal Fat WaterFat = Motion-corrected version of the image to its left.
# 3248Skin Imaging - J.K. Barral et al.15/16 Conclusions Mirrashed, Skin Research and Technology, 10: , 2004 IDEAL efficient at separating fat and water at 7 T Motion correction needed and effective (rigid-body motion) High-resolution achieved without contrast agent Long scan time Skin deformable: non-rigid motion not accounted for
# 3248Skin Imaging - J.K. Barral et al.16/16 Thank you! Contact: