AJR:195, October 2010
Boris Buerke, Michael Puesken, Stephan Muter, Matthias Weckesser, Joachim Gerss, Walter Heindel, Johannes Wessling
OBJECTIVE. The purpose of this study was to assess the measurement accuracy and re-producibility of semiautomated metric and volumetric lymph node analysis in MDCT.
MATERIALS AND METHODS. Whole-body CT with IV contrast administration was performed on 112 patients. Peripheral (cervical, axillary, and inguinal), abdominal, and tho¬racic lymph nodes were evaluated independently by two radiologists both manually and with semiautomated segmentation software. Long-axis diameter, short-axis diameter, and volume were measured. Agreement between the semiautomated and manual measurements (mea-surement error), need for manual correction, and relative interobserver differences were de-termined. Statistical analysis encompassed the variance inhomogeneity test, intraclass corre-lation coefficients, and Bland-Altman plots.
RESULTS. In total, 742 peripheral (cervical, axillary, and inguinal), abdominal, and thoracic lymph nodes (mean diameter, 13.2 ± 4.3 mm; range, 4-37 mm ) were evaluated. Semiautomatic segmentation without need for further correction was possible for 480 of 742 lymph nodes (64.7%). Calculation of intraclass correlation coefficients revealed high correla¬tion between manual and semiautomatic measurements (r = 0.70-0.81) with a slight trend to¬ward size overestimation for semiautomatic short-axis diameter (14.3%; limits of agreement, -34.3%, 62.9%) and long-axis diameter (11.7%; limits of agreement, -25.2%, 48.5%). Bland-Altman plots showed significantly (p < 0.0001) lower interobserver differences for semiauto¬mated short-axis diameter (1.2%; 95% CI,-39.9% to 42.3%) compared with the manual mea¬surement (7.6%; 95% CI, -38.7% to 53.9%). Among all locations, the relative interobserver difference for semiautomatic volume (2.9%; 95% CI, -31.4% to 37.3%) was significantly low¬er than that for manual short-axis diameter (p < 0.0001), manual long-axis diameter (0.0178), and semiautomatic short-axis diameter (p < 0.0001).
CONCLUSION. Semiautomatic short-axis diameter, particularly volume measure- ments, of lymph nodes are, irrespective of location, precise in terms of reproducibility and appear to be considerably more reliable than manual lymph node assessment.