Abstract:
:MRI of myocardial perfusion observed with an extracellular contrast agent has proven valuable for the detection of coronary artery disease. During contrast enhancement transient dark rim artifacts are sometimes visible, complicating diagnosis and quantification. In this work a quantification of the frequency offsets caused solely by the first pass of Gd-DTPA in a typical perfusion setup was made in vivo and compared with both phantom work and numerical simulations data. The results show that numerically simulated and phantom data agree well with in vivo frequency offsets. During the first pass main field distortion occurs mainly in the subendocardium, and the same pattern is always observed: positive for posterior/anterior regions, negative for septal/lateral regions (from -69 to 85 Hz). The larger myocardial frequency offsets were measured for patients with greater angles between the long axis of the heart and the direction of the main field. From these results it would appear that the frequency offsets are too weak to cause dark rim artifacts due simply to intravoxel dephasing in a typical perfusion sequence. However, when added to other sources of off-resonance it can cause dark rims in particular regions of the myocardium wall in balanced-SSFP sequences.
journal_name
Magn Reson Medjournal_title
Magnetic resonance in medicineauthors
Ferreira P,Gatehouse P,Bucciarelli-Ducci C,Wage R,Firmin Ddoi
10.1002/mrm.21723subject
Has Abstractpub_date
2008-10-01 00:00:00pages
860-70issue
4eissn
0740-3194issn
1522-2594journal_volume
60pub_type
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