TY - JOUR
T1 - Time-related changes of radiofrequency ablation lesion in the normal rabbit liver
T2 - Findings of magnetic resonance imaging and histopathology
AU - Tsuda, Masashi
AU - Rikimaru, Hiroya
AU - Majima, Kazuhiro
AU - Yamada, Takayuki
AU - Saito, Haruo
AU - Ishibashi, Tadashi
AU - Takahashi, Shoki
AU - Miyachi, Hideo
AU - Endoh, Mareyuki
AU - Yamada, Shogo
PY - 2003/8/1
Y1 - 2003/8/1
N2 - Rationale and Objectives: To study time-related magnetic resonance imaging (MRI) and histopathological findings after radiofrequency ablation (RFA) in the normal liver. Methods: Under ultrasound guidance, RFA was performed in 22 rabbits with a 15-gauge expandable probe inserted into the liver. The RF power was applied at 10 W initially with a 5-W increment every minute until RF power "roll-off" occurred. The rabbits subjected to postmortem MRI at 3days (n = 6), 2 weeks (n = 6), 4 weeks (n = 6), and 12 weeks (n = 4) after RFA. Spin-echo (SE) T1-weighted image (WI) (TR/TE=500/12) and fast SE T2-WI (TR/TE=3500/99) were obtained. The liver specimens were excised and processed for conventional histologic study. The MRI and pathologic findings were compared qualitatively and quantitatively. Results: The lesion diameters measured with MRI and liver specimen were well correlated (P < 0.05). The coagulated regions presented 2 of 4 laminar patterns on T1/T2-WI 3 days after RFA, and 2 of 3 laminar patterns on T1/T2-WI 2 to 4 weeks after RFA. 12 weeks after RFA, the signal intensity in coagulated regions increased on T1-WI with a 2-laminar pattern still visible on T2-WI, the same as that of 2 to 4 weeks. The observed pathologic changes (enlarged sinusoids, marginal fibrous tissue and hepatocyte degeneration) could be responsible for the MRI laminar patterns and signal intensity changes. Conclusion: The time-related pathologic changes of RFA lesions in rabbit livers can be reflected as laminar patterns on MR images. Understanding of the zone structure of the lesions is useful for the evaluation of follow-up MRI.
AB - Rationale and Objectives: To study time-related magnetic resonance imaging (MRI) and histopathological findings after radiofrequency ablation (RFA) in the normal liver. Methods: Under ultrasound guidance, RFA was performed in 22 rabbits with a 15-gauge expandable probe inserted into the liver. The RF power was applied at 10 W initially with a 5-W increment every minute until RF power "roll-off" occurred. The rabbits subjected to postmortem MRI at 3days (n = 6), 2 weeks (n = 6), 4 weeks (n = 6), and 12 weeks (n = 4) after RFA. Spin-echo (SE) T1-weighted image (WI) (TR/TE=500/12) and fast SE T2-WI (TR/TE=3500/99) were obtained. The liver specimens were excised and processed for conventional histologic study. The MRI and pathologic findings were compared qualitatively and quantitatively. Results: The lesion diameters measured with MRI and liver specimen were well correlated (P < 0.05). The coagulated regions presented 2 of 4 laminar patterns on T1/T2-WI 3 days after RFA, and 2 of 3 laminar patterns on T1/T2-WI 2 to 4 weeks after RFA. 12 weeks after RFA, the signal intensity in coagulated regions increased on T1-WI with a 2-laminar pattern still visible on T2-WI, the same as that of 2 to 4 weeks. The observed pathologic changes (enlarged sinusoids, marginal fibrous tissue and hepatocyte degeneration) could be responsible for the MRI laminar patterns and signal intensity changes. Conclusion: The time-related pathologic changes of RFA lesions in rabbit livers can be reflected as laminar patterns on MR images. Understanding of the zone structure of the lesions is useful for the evaluation of follow-up MRI.
KW - MRI
KW - Pathologic correlation
KW - Rabbit liver
KW - Radiofrequency ablation
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U2 - 10.1097/01.rli.0000073447.32361.b3
DO - 10.1097/01.rli.0000073447.32361.b3
M3 - Article
C2 - 12874519
AN - SCOPUS:10744224125
VL - 38
SP - 525
EP - 531
JO - Investigative Radiology
JF - Investigative Radiology
SN - 0020-9996
IS - 8
ER -