Aug 23, 1995 - 1Department of Radiology, University of Florida. College of Medicine, 1600 SW. Archer Ad., Box. 100374,. Gainesville,. FL 32610. Address.
379
Ring Enhancement in Ultrasmall Superparamagnetic Iron Oxide MR Imaging: A Potential New Sign for Characterization
Patricia J. Memgo1 T. Helmberger1’2 Ana I. Nicolas1 Pablo R. Ros1
OBJECTIVE. ring
of Liver
We performed
enhancement
after
this study
Lesions
to evaluate
IV administration
of
an
the incidence ultrasmall
and significance
superparamagnetic
of iron
oxide (USPIO) particle (Code 7227), a reticuloendothelial contrast agent with potential use as a blood-pool agent, for characterizing focal hepatic lesions. SUBJECTS AND METHODS. Conventional Ti-weighted imaging, fat-suppressed Tiweighted imaging, conventional T2-weighted imaging, and fast T2-weighted imaging of the liver were obtained in 27 patients with 43 liver lesions before and after IV administration of a USPIO preparation. All lesions were larger than 1 cm; 29 were malignant and 14 were benign. Diagnosis was confirmed in all cases, either pathologically
(1 9 patients)
or by follow-up
examination
(eight
patients).
Two
readers
Indepen-
dently evaluated each pulse sequence for the presence of ring enhancement of hepatic lesions. RESULTS. Ring enhancement was noted only on Ti-weighted images, with no ring enhancement evident on 12-weighted images.Twenty of 43 (47%) lesions showed ring enhancement, including 18 of 29 (62%) malignant lesions and two of i4 (14%) benign lesions (p < .01 1 ; Wilcoxon signed rank test). Fat-suppressed Ti-weighted imaging showed ring enhancement better than or equal to conventional Ti-weighted imaging in all cases, with ring enhancement of 15 of i 8 (83%) malignant lesions and two of two benign lesions better demonstrated on fat-suppressed Ti-weighted imaging sequences (p .025). CONCLUSION. Ring enhancement after IV administration of Code 7227 is a frequent finding seen more often with malignant than benign lesions, potentially identitying a new MR imaging feature for the characterization of liver lesions. The identification
of
blood-pool AJR
ring
effects
i996;i
Received July 7, 1995; August23, 1995.
accepted
after
revision
Presented at the annual meeting of the Amencan Roentgen Ray Society, washington, DC, AprilMay 1995. Supported Magnetics.
in pant by a grant
from
Advanced
1Department of Radiology, University of Florida College of Medicine, 1600 SW. Archer Ad., Box 100374,
Gainesville,
spondence 2institute
FL
32610.
for Diagnostic
come-
0361-803X/96/1662-379
Roentgen
Ray Society
Klinikum
University,
Mu-
images
attests
to the
significant
uptake
and MR imaging
capabilities
of superpanamagnetic
have been characterized, with correlation among particle size, biologic and enhancement properties [1-9]. Recently, ultmasmall supempanamag-
netic iron oxides (USPIO) have been developed (
