Dg. Mitchell et al., FATTY TISSUE ON OPPOSED-PHASE MR-IMAGES - PARADOXICAL SUPPRESSION OF SIGNAL INTENSITY BY PARAMAGNETIC CONTRAST AGENTS, Radiology, 198(2), 1996, pp. 351-357
PURPOSE: To evaluate paradoxically decreased signal intensity on gadol
inium-enhanced opposed-phase magnetic resonance (MR) images of fatty t
issues. MATERIALS AND METHODS: Unenhanced and gadolinium-enhanced axia
l, opposed-phase, gradient-echo images were analyzed visually and with
region-of-interest measurements. Tissues measured included adipose ti
ssue (n = 10), angiomyolipomas (n 8), and vertebral hemangiomas (n = 7
). Additionally, a phantom of mayonnaise, soybean oil, agarose, and wa
ter (63% lipid signal) with variable concentrations of gadolinium chel
ate was imaged with similar technique. RESULTS: After administration o
f gadolinium chelate, signal intensity reduction averaged 18% for adip
ose tissue, 34% (72-48 units) for predominately fatty angiomyolipomas,
and 39% (85-52 units) for vertebral hemangiomas. Imaging of the phant
om showed a maximum of 79% reduction in signal intensity with gadolini
um chelate (227-47 units). DISCUSSION: Gadolinium-enhanced opposed-pha
se images depict a significant loss in signal intensity in tissues wit
h MR signal predominately from lipid. Gadolinium chelate increases the
signal of water within fatty tissues, which increases the amount of l
ipid signal suppression due to destructive interference between water
and lipid proton magnetizations.