Inadequacy of manual measurements compared to automated CT volumetry in assessment of treatment response of pulmonary metastases using RECIST criteria

Department of Radiology, Klinikum rechts der Isar, Technical University Munich, Germany.
European Radiology (Impact Factor: 4.01). 04/2006; 16(4):781-90. DOI: 10.1007/s00330-005-0036-x
Source: PubMed


The purpose of this study was to compare relative values of manual unidimensional measurements (MD) and automated volumetry (AV) for longitudinal treatment response assessment in patients with pulmonary metastases. Fifty consecutive patients with pulmonary metastases and repeat chest multidetector-row CT (median interval=2 months) were independently assessed by two radiologists for treatment response using Response Evaluation Criteria In Solid Tumours (RECIST). Statistics included relative measurement errors (RME), intra-/interobserver correlations, limits of agreement (95% LoA), and kappa. A total of 202 metastases (median volume=182.22 mm(3); range=3.16-5,195.13 mm(3)) were evaluated. RMEs were significantly higher for MD than for AV (intraobserver RME=2.34-3.73% and 0.15-0.22% for MD and AV respectively; P<0.05. Interobserver RME=3.53-3.76% and 0.22-0.29% for MD and AV respectively; P<0.05). Overall correlation was significantly better for AV than for MD (P<0.05). Intraobserver 95% LoAs were -1.85 to 1.75 mm for MD and -11.28 to 9.84 mm(3) for AV. The interobserver 95% LoA were -1.46 to 1.92 mm for MD and -11.17 to 9.33 mm(3) for AV. There was total intra-/interobserver agreement on response using AV (kappa=1). MD intra- and interobserver agreements were 0.73-0.84 and 0.77-0.80 respectively. Of the 200 MD response ratings, 28 (14/50 patients) were discordant. Agreement using MD dropped significantly from total remission to progressive disease (P<0.05). We therefore conclude that AV allows for better reproducibility of response evaluation in pulmonary metastases and should be preferred to MD in these patients.

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    • "However, relatively high inter- and intra-observer variability was found in the measurement of lung tumor size on CT scans, which can lead to an incorrect interpretation of tumor response [25]. Accurate and objective size measurement and detection of newly emerged metastatic nodules are of similar importance for the evaluation of therapeutic responses in malignancy [26], [27]. In clinical evaluation, objective information additional to the original CT images is highly helpful. "
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    • "Manual measurements are also subject to high inter- and intra-observer variability. Several studies have suggested that manual measurements of tumor size by radiologists are inconsistent [2], [3], [4] and should not be relied upon to provide ground truth. In response to these issues, semi-automated measurement methods have been developed to improve tumor measurement efficiency and reduce inconsistency among radiologists. "
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