MRI of liver: a comparison of CNR enhancement using high dose and low doseferumoxide infusion in patients with colorectal liver metastases

The purpose of this study was to compare the effects of high dose (HD) and low dose (LD) ferumoxides infusions on lesion-to-liver contrast-to-noise ra tio (CNR) using four different T-2-weighted MR sequences. Seventy-three pat ients with known colorectal liver metastases underwent T-2-weighted fast sp in echo (FSE) imaging before and after ferumoxides. After ferumoxides, T-2- weighted dual echo (DE) and T-2-weighted GRE FLASH images were also obtaine d. To evaluate the relationship between TE length and lesion-to-liver CNR, the same FLASH sequence was repeated in 18 LD patients after lengthening th e TE. Ferumoxides was administered at a dose of 15 mu mol/kg (HD) and 7.5 m u mol/kg (LD) in 45 and 28 patients, respectively. The effects of HD and LD ferumoxides infusions were measured as the percentage signal intensity cha nge (PSIC) in the liver and lesions, lesion-to-liver CNR and the change in lesion-to-liver CNR (Delta CNR). In both LD and HD groups, all CNR values o btained after SPIO were significantly greater than those observed with unen hanced FSE (p < 0.01). There was no significant difference between the mean CNR values obtained with either dose for any sequence. With the FLASH sequ ence, CNR increased progressively with longer TE. At the longest TE of 26 m s, mean CNR was higher than that recorded with any of the other sequences. Although mean liver PSIC was significantly greater in the HD group than in the LD group (p < 0.01) because the mean lesion PSIC was also greater in th e HD group, the mean Delta CNR after ferumoxides was not significantly diff erent in the two groups. LD SPIO enhanced MR significantly increases lesion -to-liver CNR compared with unenhanced images. At 1.0 T, HD and LD ferumoxi des infusions produce comparable lesion-to-liver CNR. Our results suggest t hat at 1.0 T ferumoxides may be administered at a dose of 7.5 mu mol/kg wit hout loss of image quality. (C) 2000 Elsevier Science Inc. All rights reser ved.