Radiology, Vol 153, 467-470, Copyright © 1984 by Radiological Society of North America
Experimental pulmonary emboli detected using magnetic resonance
G Gamsu, M Hirji, EH Moore, WR Webb and A Brito
Experimental pulmonary emboli that were labelled with non-magnetic barium
threads and produced using aminocaproic acid were introduced into the
internal jugular veins of five dogs. Transverse axial magnetic resonance
(MR) images (0.35 T, 15 MHz) and CT scans (2.0 or 4.8 seconds, G.E. 9800 or
8800 scanner) were obtained from the lung apex to base in each animal. The
MR images were gated to the cardiac cycle, and spin echo techniques were
used (TR = gated to the cardiac cycle; TE = 28 and 56 msec). Nineteen sites
of embolism were determined from the CT scans. Two observers, who had no
knowledge of the number or position of the emboli, individually assessed
the MR images and marked the sites of emboli on clear acetate overlays.
Each observer detected 12 of 19 emboli (63%) and each had one false
positive result. Of the 19 emboli, six were central or parahilar and 13
were in the outer two thirds of the lungs. Three (first observer) or four
(second observer) of the seven false negative results were central. In
retrospect, two central emboli were mistaken for hilar fat. One peripheral
embolus was not visible, even in retrospect. The potential for MR to
demonstrate relatively small pulmonary emboli has been shown. Clinical
trials in patients seem warranted.
