Hepatic lesion detection after superparamagnetic iron oxide enhancement: comparison of five T2-weighted sequences at 1.0 T by using alternative-free response receiver operating characteristic analysis.
OBJECTIVE
To compare the accuracy of five T2-weighted sequences in the detection of liver lesion at magnetic resonance (MR) imaging after superparamagnetic iron oxide (SPIO) enhancement.


METHODS
Forty-nine candidates for hepatic resection with known coloretal metastases were examined. Before SPIO enhancement, fast spin-echo (SE) images were obtained. After enhancement, the same fast SE sequence and long; TR/short TE, short TE, long TR/TE, and T2-weighted fast low-angle shot (FLASH) sequences were used. All images were viewed independently by four observers who were blinded to the results of the other imaging sequences, the results of the other observers, and the findings at surgery and histopathologic examination. Four weeks after the initial reading, the combined long TR/short TE and long TR/TE dual-echo images were also viewed as an additional set. The alternative free response receiver operating characteristic (ROC) method was used to analyze the results, which were correlated with findings at surgery, intraoperative ultrasonography, and histopathologic examination.


RESULTS
Irrespective of lesion size, the accuracy of all sequences after enhancement was significantly greater than that of the nonenhanced fast SE sequence (P < .01). Dual-echo and FLASH sequences were significantly more accurate than the enhanced fast SE sequence (P < .03 or P < .02, respectively). For all lesions, lesions smaller than 1 cm, and lesions 1 cm or larger, mean accuracies were as follows: dual-echo, 0.75, 0.54, and 0.93; FLASH, 0.75, 0.54, and 0.95; and enhanced fast SE, 0.72, 0.49, and 0.92.


CONCLUSIONS
At 1.0 T, dual-echo and FLASH sequences are the most accurate pulse sequences after SPIO enhancement.
Ward
J
J
Department of Clinical Radiology, St James's University Hospital, Leeds, United Kingdom. 113566.2505@compuserve.com
Chen
F
F
Guthrie
J A
JA
Wilson
D
D
Lodge
J P
JP
Wyatt
J I
JI
Robinson
P J
PJ
D000368:Aged; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000601:surgery; D003287:Contrast Media; D003937:Diagnosis, Differential; D005260:Female; D005290:Ferric Compounds; D006801:Humans; D007089:Image Enhancement; D008099:Liver / Q000473:pathology; D008113:Liver Neoplasms / Q000175:diagnosis / Q000556:secondary* / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests
D003287:Contrast Media; D005290:Ferric Compounds; C000499:ferric oxide