Size determination and response assessment of liver metastases with computed tomography--comparison of RECIST and volumetric algorithms.
OBJECTIVE
To compare different three-dimensional volumetric algorithms (3D-algorithms) and RECIST for size measurement and response assessment in liver metastases from colorectal and pancreatic cancer.


METHODS
The volumes of a total of 102 liver metastases in 45 patients (pancreatic cancer, n=22; colon cancer, n=23) were estimated using three volumetric methods (seeded region growing method, slice-based segmentation, threshold-based segmentation) and the RECIST 1.1 method with volume calculation based on the largest axial diameter. Each measurement was performed three times by one observer. All four methods were applied to follow-up on 55 liver metastases in 29 patients undergoing systemic treatment (median follow-up, 3.5 months; range, 1-10 months). Analysis of variance (ANOVA) with post hoc tests was performed to analyze intraobserver variability and intermethod differences.


RESULTS
ANOVA showed significant higher volumes calculated according to the RECIST guideline compared to the other measurement methods (p<0.001) with relative differences ranging from 0.4% to 41.1%. Intraobserver variability was significantly higher (p<0.001) for RECIST and threshold based segmentation (3.6-32.8%) compared with slice segmentation (0.4-13.7%) and seeded region growing method (0.6-10.8%). In the follow-up study, the 3D-algorithms and the assessment following RECIST 1.1 showed a discordant classification of treatment response in 10-21% of the patients.


CONCLUSIONS
This study supports the use of volumetric measurement methods due to significant higher intraobserver reproducibility compared to RECIST. Substantial discrepancies in tumor response classification between RECIST and volumetric methods depending on applied thresholds confirm the requirement of a consensus concerning volumetric criteria for response assessment.
Klinik für Radiologie, Campus Virchow-Klinikum, Charité - Universitätsmedizin, Berlin, Germany. Electronic address: jan-holger.rothe@charite.de.
Jan Holger
JH
Rothe
Christian
C
Grieser
Lukas
L
Lehmkuhl
Dirk
D
Schnapauff
Carmen Perez
CP
Fernandez
Martin H
MH
Maurer
Axel
A
Mussler
Bernd
B
Hamm
Timm
T
Denecke
Ingo G
IG
Steffen
D000328:Adult; D000368:Aged; D000465:Algorithms; D005260:Female; D005858:Germany / Q000453:epidemiology; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008113:Liver Neoplasms / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000556:secondary*; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden