Dynamic enhancement features of gadophrin-2 on magnetic resonance imaging: an experimental model of VX2 carcinoma and bacterial abscess in rabbit thigh.
OBJECTIVE
To determine the dynamic enhancement features of malignant tumor and bacterial abscess in rabbits on magnetic resonance imaging (MRI) after injection of gadolinium mesoporphyrin (gadophrin-2) and to correlate them with histopathologic findings.


METHODS
Six VX2 carcinomas and six bacterial abscesses were experimentally induced in either thigh of six rabbits. Dynamic T1-weighted MRI was performed before and 1, 3, 5, 10, 30 minutes and 16, 21, 72 hours after intravenous injection of gadophrin-2 (0.05 mmol/kg). The enhancement ratios of lesions were calculated for each time point. All tumors and abscesses were sectioned along the same plane of MR images for a detailed MRI-histopathologic correlation.


RESULTS
In tumors and abscesses, peripheral-rim enhancement appeared on MRI at 1, 3, 5, 10, 30 minutes after injection of gadophrin-2. The lesions showed peripheral enhancement with irregular central enhancement or diffuse enhancement after 16 and 21 hours, and there was diffuse enhancement of the entire lesion after 72 hours. Enhancement ratios in tumor-necrosis mixed area and the pure necrotic area in VX2 carcinoma and the central cavity in bacterial abscess were significantly lower than that in the compact cellular portion in VX2 carcinoma and the wall of abscess at early phase (P < 0.01). On delayed phase MRI, there was no statistical significance in enhancement ratio of three histologic parts of VX2 carcinoma (P > 0.05) and two histologic parts of abscess (P > 0.05). Rapid enhancement at early phase with diminishing signal intensity at delayed phase is indicative of viable compact tumor and delayed strong enhancement is indicative of necrosis.


CONCLUSIONS
It is difficult to distinguish an abscess from a tumor on gadophrin-2 enhanced MRI especially when intratumoral necrosis is prominent. However, the trend and degree of enhancement by gadophrin-2 could be helpful in discrimination between viable tumor and tumor necrosis.
Ju Lee
Hyun
H
Department of Radiology and Clinical Research Institute, Seoul National University Hospital, Seoul National University Medical Research Center, Chongno-gu, Seoul, Korea.
Kim
In-One
IO
Kim
Tae Kyoung
TK
Hyung Kim
Se
S
Choi
Jin-Il
JI
Woo Lee
Joon
J
Kyung Moon
Woo
W
Choi
Byung Ihn
BI
Chung Han
Man
M
Weinmann
Hanns-Joachim
HJ
Hyun Chang
Kee
K
D000038:Abscess / Q000473:pathology*; D000818:Animals; D002277:Carcinoma / Q000473:pathology*; D003287:Contrast Media / Q000008:administration & dosage* / Q000493:pharmacokinetics; D004927:Escherichia coli Infections / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008652:Mesoporphyrins / Q000008:administration & dosage* / Q000493:pharmacokinetics; D008665:Metalloporphyrins / Q000008:administration & dosage* / Q000493:pharmacokinetics; D009368:Neoplasm Transplantation; D009374:Neoplasms, Experimental / Q000473:pathology*; D011817:Rabbits; D013848:Thigh
D003287:Contrast Media; D008652:Mesoporphyrins; D008665:Metalloporphyrins; C118579:gadophrin-2