Prediction of viable tumor in hepatocellular carcinoma treated with transcatheter arterial chemoembolization: usefulness of attenuation value measurement at quadruple-phase helical computed tomography.
OBJECTIVE
To assess the usefulness of attenuation value measurement at quadruple-phase helical computed tomography (CT) for predicting viable tumor in hepatocellular carcinoma (HCC) treated with transcatheter arterial chemoembolization (TACE).


METHODS
Thirty-two patients who had an iodized-oil defect area (IODA) in HCCs treated with TACE were included in our study; these patients were divided into group 1 (n = 21) with viable tumor and group 2 (n = 11) without viable tumor in the IODA. All the patients underwent quadruple-phase helical CT (unenhanced and contrast-enhanced hepatic arterial, portal venous and equilibrium phases) before and after TACE. The attenuation difference of the IODA between unenhanced and each contrast-enhanced phase was measured, and the attenuation degree of the IODA relative to the hepatic parenchyma were subjectively assessed and then compared between the 2 groups.


RESULTS
The mean attenuation differences of the IODAs were 28.8, 35.9, and 25.6 Hounsfield unit (HU) in group 1 and 0.4, 1.9, and 2.0 HU in group 2 at the hepatic arterial, portal venous, and equilibrium phases, respectively, with statistically significant difference for each phase (P < 0.05). The IODAs had attenuation difference of more than 20 HU on at least 1 contrast-enhanced phase in group 1 and less than 5 HU at all contrast-enhanced phases in group 2. For the attenuation degree of IODAs relative to the hepatic parenchyma, 12 patients (57%) showed hyperattenuation at the hepatic arterial phase, and remaining nine (43%) at the hepatic arterial phase and all patients at the portal venous and equilibrium phases showed isoattenuation or hypoattenuation in group 1. In group 2, all the patients showed hypoattenuation at all the 3 phases.


CONCLUSIONS
The presence of viable tumor of the IODA in HCC treated with TACE can be precisely assessed by measuring attenuation values, strongly suggesting viable tumor when the attenuation difference is more than 20 HU on at least 1 contrast-enhanced phase at quadruple-phase helical CT.
Kim
Seong Hyun
SH
Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea.
Lee
Won Jae
WJ
Lim
Hyo K
HK
Lim
Jae Hoon
JH
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006528:Carcinoma, Hepatocellular / Q000150:complications / Q000175:diagnosis* / Q000628:therapy*; D016461:Chemoembolization, Therapeutic / Q000295:instrumentation / Q000379:methods*; D003287:Contrast Media / Q000008:administration & dosage; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007479:Iopamidol; D008103:Liver Cirrhosis / Q000150:complications; D008113:Liver Neoplasms / Q000150:complications / Q000175:diagnosis* / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D018365:Neoplasm, Residual; D011237:Predictive Value of Tests; D011856:Radiographic Image Enhancement / Q000379:methods; D012189:Retrospective Studies; D036542:Tomography, Spiral Computed / Q000379:methods*
D003287:Contrast Media; D007479:Iopamidol