OPENING SESSION - ismrm

Monday AM
17:06 132. Imaging of Metallic Implant Using 3D Ultrashort Echo Time (3D UTE) Pulse
Sequence
Jiang Du 1 , Kelly Borden 1 , Eric Diaz 1 , Mark Bydder 1 , Won Bae 1 , Shantanu Patil 2 , Graeme
Bydder 1 , Christine Chung 1
1 Radiology, University of California, San Diego, CA, United States; 2 Shiley Center for Orthopedic Research
and Education, La Jolla, CA, United States
Magnetic resonance imaging (MRI) near metal implants suffers from severe artifacts due to large metal-induced field
inhomogeneities. The steep field gradients near metal implants result in increased intra-voxel dephasing and a much shortened T2*.
Clinical gradient echo (GE) sequences suffer from large signal loss. Spin echo (SE) type sequences only partly refocus the dephased
spins, resulting in spatially dependent signal voids and pile-ups. Here we present a 3D ultrashort TE (UTE) sequence which employs
short hard pulse excitation and 3D radial sampling with a nominal TE of 8 µs to image metallic implants with markedly reduced
artifact.
17:18 133. kf ARC Reconstruction for Improving MRI Around Metal Using MAVRIC
Peng Lai 1 , Weitian Chen 1 , Christina Chen 2 , Kevin M. Koch 3 , Anja CS. Brau 1
1 Applied Science Laboratory, GE Healthcare, Menlo Park, CA, United States; 2 Stanford University, Stanford,
CA, United States; 3 Applied Science Laboratory, GE Healthcare, Waukesha, WI, United States
This work developed a new method, kf ARC, for highly accelerated MAVRIC imaging around metal implants. The proposed method
utilizes both k-space correlation and spectral correlation between adjacent spectral images to improve reconstruction. kf ARC was
evaluated on 2 patients with metallic implants in comparison with conventional parallel imaging. Our results show that kf ARC can
significantly improve image quality at high acceleration factors and is a promising approach to fast MAVRIC data acquisition.
17:30 134. Morphological and Quantitative Evaluation of Meniscal Calcifications by Novel 2D
IR and 3D UTE MR Techniques
Patrick Omoumi 1,2 , Eric S. Diaz 1 , Jiang Du 1 , Sheronda S. Statum 1 , Won C. Bae 1 , Graeme
Bydder 1 , Christine B. Chung 1
1 University of California, San Diego, San Diego, CA, United States; 2 Cliniques Universitaire St Luc, Brussels,
Belgium
Meniscal calcifications are frequent and likely alter the normal biomechanics of the meniscus. Although MR imaging is the noninvasive
technique of choice for the evaluation of meniscal pathology, it does not allow the facile visualization of meniscal
calcifications. This is due to a lack of contrast (both calcifications and menisci have relatively short T2 relaxation times), and a lack of
saptial résolution with standard clinical sequences. We describe novel MR imaging techniques based on 2D-UTE inversion recovery
and 3D-UTE data acquisition to address these factors. We assessed the ability of these sequences to allow the visualization,
characterization and quantitative evaluation of meniscal calcifications.
17:42 135. Fiber Tracking of Dipolar Directions in the Meniscus
Nikolaus M. Szeverenyi 1 , Graeme M. Bydder 1
1 Radiology, University of California, San Diego, San Diego, CA, United States
This study examines a method to extract and use dipolar information to characterize an ex-vivo meniscus sample. A goat meniscus
was embedded in a spherical epoxy ball and the MR signal intensity examined as a function of orientation to a 3T static field.
Unaveraged dipolar interactions caused dramatic signal variations in sub-structures. After correcting for coil sensitivity and coregistering
all images, a principle dipolar direction was extracted for each voxel. This directional data could be analyzed and viewed
as a direction map, similar to DTI brain data. The intensity fluctuations provided a FA map. Fiber tracks were generated.
17:54 136. Ultrashort Echo Imaging (UTE) of Rotator Cuff Repair in an Ovine Model
Matthew F. Koff 1 , Hollis G. Potter 1
1 Department of Radiology and Imaging, Hospital for Special Surgery, New York, United States
The rotator cuff tendons typically display low signal on standard clinical images due to the highly ordered collagen within the tissue.
Ultrashort echo (UTE) imaging creates contrast for visualization and for T2* quantitation. This study used T2* mapping to evaluate
rotator cuff repair in an ovine model. Reparative surgery was performed to the supraspinatus tendon in sheep. Shoulders were scanned
ex-vivo 8 weeks post-operatively. T2* values of repaired tendon were significantly longer than normal tendon. The T2* values
decreased in magnitude along the length of the repair, but not significantly. This pilot study highlights the use of UTE for quantitative
evaluation of soft tissue repair.
18:06 137. Detection of Dipolar Splitting in Rodent Tendons as a Function Axial Position with
Double-Quantum Filtered Spectroscopic Imaging
Henry H. Ong 1 , Joseph J. Sarver 2 , Jason E. Hsu 2 , Louis J. Soslowsky 2 , Felix W. Wehrli 1
1 Laboratory for Structural NMR Imaging, Department of Radiology, University of Pennsylvania School of
Medicine, Philadelphia, PA, United States; 2 McKay Orthopaedic Research Laboratory, University of
Pennsylvania, Philadelphia, PA, United States
Tendons are comprised of parallel collagen fibers that connect muscles to bone. Collagen-associated water has anisotropic rotational
motion, which gives rise to residual dipolar splitting in 1H NMR. Double-quantum filtered (DQF) NMR and MRI can be used to
observe the splitting and study the biophysical and structural properties of tendon. Here, we modified a DQF 1D spectroscopic
imaging sequence to obtain 1H DQF spectra along the axis of the flexor digitorum profundus (FDP) tendons from rat hind limbs and
show spectral differences in the region that wraps under the calcaneus, which experiences compressive forces.