Characterization of focal hepatic lesions with ferumoxides-enhanced MR imaging: utility of T1-weighted spoiled gradient recalled echo images using different echo times.
OBJECTIVE
To evaluate the different signal characteristics of focal hepatic lesions on ferumoxides-enhanced MR imaging, including T1-weighted spoiled gradient recalled echo (GRE) images using different echo times (TE) and T2- and T2*-weighted images.


METHODS
Ferumoxides-enhanced MR imaging was performed using a 1.5-T system in 46 patients who were referred for evaluation of known or suspected hepatic malignancies. One hundred and seven lesions (42 hepatocellular carcinomas [HCC], 40 metastases, 13 cysts, eight hemangiomas, three focal nodular hyperplasias [FNHs], and one cholangiocarcinoma) were evaluated. Postcontrast MR imaging included 1) T2-weighted FSE; 2) T2*-weighted GRE; 3) T1-weighted spoiled GRE using moderate (TE = 4.2-4.4 msec) TE; and 4) minimum (TE = 1.8-2.1 msec) TE. Signal intensities of the focal lesions were rated by two radiologists in conference as follows: hypointense, isointense or invisible, hyperintense, and markedly hyperintense. Lesion-to-liver contrast-to-noise ratio (C/N) was measured by one radiologist for a quantitative assessment.


RESULTS
On ferumoxides-enhanced FSE images, 92% of cysts were "markedly hyperintense" and most of the other lesions were "hyperintense", and the mean C/N of cysts was significantly higher than that of other focal lesions. T2*-weighted GRE images showed most lesions with similar hyperintensities and the mean C/N was not significantly different between any two types of lesion. T1-weighted GRE images using moderate TE showed all FNHsand hemangiomas, 29 (69%) HCCs and eight (20%) metastases as "hyperintense". On T1-weighted GRE images using minimum TE, however, all HCCs and metastasis except one were iso- or hypointense, while all of the FNHs and hemangiomas were hyperintense. Ring enhancement was highly suggestive of malignant lesions, and was more commonly seen on the minimum TE images than on the moderate TE images.


CONCLUSIONS
Addition of T1-weighted GRE images using minimum and moderate TE is helpful for characterizing focal lesions in ferumoxides-enhanced MR imaging.
Kim
Joo Hee
JH
Department of Diagnostic Radiology, Yonsei University College of Medicine, Seoul, Republic of Korea.
Kim
Myeong-Jin
MJ
Suh
Sang Hyun
SH
Chung
Jae-Joon
JJ
Yoo
Hyung Sik
HS
Lee
Jong Tae
JT
D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D006528:Carcinoma, Hepatocellular / Q000175:diagnosis* / Q000556:secondary; D003287:Contrast Media; D003560:Cysts / Q000175:diagnosis; D003911:Dextrans; D003937:Diagnosis, Differential; D017352:Echo-Planar Imaging / Q000379:methods*; D005260:Female; D052203:Ferrosoferric Oxide; D020518:Focal Nodular Hyperplasia / Q000175:diagnosis; D006391:Hemangioma / Q000175:diagnosis; D006801:Humans; D007089:Image Enhancement; D007501:Iron; D008113:Liver Neoplasms / Q000175:diagnosis* / Q000556:secondary; D058185:Magnetite Nanoparticles; D008297:Male; D008875:Middle Aged; D010087:Oxides
D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; D010087:Oxides; D007501:Iron; C065507:ferumoxides; D052203:Ferrosoferric Oxide