AJR:194, February 2010
Seitaro Oda, Kazuo Awai, Kohei Murao, Akio Ozawa,Yumi Yanaga, Koichi Kawanaka,Yasuyuki Yamashita
OBJECTIVE. The purpose of this study was to investigate the accuracy and reproducibil¬ity of results acquired with computer-aided volumetry software during MDCT of pulmonary nodules exhibiting ground-glass opacity.
MATERIALS AND METHODS. To evaluate the accuracy of computer-aided volum¬etry software, we performed thin-section helical CT of a chest phantom that included simu¬lated 3-, 5-, 8-, 10-, and 12-mm-diameter ground-glass opacity nodules with attenuation of -800, -630, and -450 HU. Three radiologists measured the volume of the nodules and calcu¬lated the relative volume measurement error, which was defined as follows: (measured nodule volume minus assumed nodule volume ÷ assumed nodule volume) x 100. Two radiologists performed two independent measurements of 59 nodules in humans. Intraobserver and inter¬observer agreement was evaluated with Bland-Altman methods.
RESULTS. The relative volume measurement error for simulated ground-glass opacity nodules measuring 3 mm ranged from 51.1% to 85.2% and for nodules measuring 5 mm or more in diameter ranged from -4.1% to 7.1%. In the clinical study, for intraobserver agree¬ment, the 95% limits of agreement were -14.9% and -13.7% and -16.6% to 15.7% for observ¬ers A and B. For interobserver agreement, these values were -16.3% to 23.7% for nodules 8 mm in diameter or larger.
CONCLUSION. With computer-aided volumetry of ground-glass opacity nodules, the relative volume measurement error was small for nodules 5 mm in diameter or larger. In¬traobserver and interobserver agreement was relatively high for nodules 8 mm in diameter or larger.