Semiautomated segmentation for volumetric analysis of intratumoral ethiodol uptake and subsequent tumor necrosis after chemoembolization.
OBJECTIVE
Linear measurements, such as those described by the Response Evaluation Criteria in Solid Tumors (RECIST) criteria, may be limited for assessment of response after transarterial chemoembolization (TACE). The purpose of this pilot study was to show intra- and interobserver reproducibility of volumetric measurements of Ethiodol (ethiodized oil) seen within tumor 24 hours after TACE and of necrotic and viable tumor 1 month after treatment. Volumetric measurements are compared with linear measurements and survival outcomes.


METHODS
Between 2006 and 2009, 37 consecutive TACE procedures were performed in 27 patients with hepatic malignancies. CT images obtained 24 hours and 1 month after TACE were retrospectively analyzed. Three observers measured volumes twice. Intraoperator reproducibility was determined using Wilcoxon's signed rank test to assess whether the difference in each volumetric measurement approaches zero. The intraclass correlation coefficient (ICC) and Bland-Altman plots were used to determine interoperator reproducibility. Survival data were retrospectively obtained from the electronic medical record.


RESULTS
Good intraobserver reproducibility and interobserver reproducibility (p > 0.05, ICC > 0.9, respectively) were shown for Ethiodol, whole tumor, and necrotic tumor volumes. The volume of Ethiodol correlated with subsequent necrotic tumor volume (p = 0.009), reduction in whole tumor volume (p = 0.004), and patient survival (p = 0.029). Kaplan-Meier curves suggest that Ethiodol accumulation in more than 50% of the tumor and a 10% or greater increase in the volume of necrotic tumor correlated with survival (p = 0.028 and 0.047, respectively).


CONCLUSIONS
Semiautomated volumetric analysis can be performed with good intra- and interobserver reproducibility. The volume of Ethiodol accumulated in the tumor after TACE correlates with subsequent necrosis. These early measurements may predict survival outcomes.
Monsky
Wayne L
WL
Department of Radiology, University of California, UC Davis Medical Center, Sacramento, 95817, USA. wayne.monsky@ucdmc.ucdavis.edu
Kim
Isaac
I
Loh
Shaun
S
Li
Chin-Shang
CS
Greasby
Tamara A
TA
Deutsch
Larry-Stuart
LS
Badawi
Ramsey D
RD
D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D001331:Automation; D002276:Carcinoid Tumor / Q000000981:diagnostic imaging / Q000628:therapy; D006528:Carcinoma, Hepatocellular / Q000000981:diagnostic imaging / Q000628:therapy; D016461:Chemoembolization, Therapeutic / Q000379:methods*; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000628:therapy; D004998:Ethiodized Oil / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D005260:Female; D006801:Humans; D007340:Insulinoma / Q000000981:diagnostic imaging / Q000628:therapy; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D009336:Necrosis; D010865:Pilot Projects; D011857:Radiographic Image Interpretation, Computer-Assisted; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012984:Software; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
D000970:Antineoplastic Agents; D004998:Ethiodized Oil