Computerized margin and texture analyses for differentiating bacterial pneumonia and invasive mucinous adenocarcinoma presenting as consolidation

<div><p>Radiologists have used margin characteristics based on routine visual analysis; however, the attenuation changes at the margin of the lesion on CT images have not been quantitatively assessed. We established a CT-based margin analysis method by comparing a target lesion with normal lung attenuation, drawing a slope to represent the attenuation changes. This approach was applied to patients with invasive mucinous adenocarcinoma (n = 40) or bacterial pneumonia (n = 30). Correlations among multiple regions of interest (ROIs) were obtained using intraclass correlation coefficient (ICC) values. CT visual assessment, margin and texture parameters were compared for differentiating the two disease entities. The attenuation and margin parameters in multiple ROIs showed excellent ICC values. Attenuation slopes obtained at the margins revealed a difference between invasive mucinous adenocarcinoma and pneumonia (<i>P</i><0.001), and mucinous adenocarcinoma produced a sharply declining attenuation slope. On multivariable logistic regression analysis, pneumonia had an ill-defined margin (odds ratio (OR), 4.84; 95% confidence interval (CI), 1.26–18.52; <i>P</i> = 0.02), ground-glass opacity (OR, 8.55; 95% CI, 2.09–34.95; <i>P</i> = 0.003), and gradually declining attenuation at the margin (OR, 12.63; 95% CI, 2.77–57.51, <i>P</i> = 0.001). CT-based margin analysis method has a potential to act as an imaging parameter for differentiating invasive mucinous adenocarcinoma and bacterial pneumonia.</p></div

Univariate and multivariable analyses of CT visual assessment and binary slope for differentiation of invasive mucinous adenocarcinoma and bacterial pneumonia.

<p>Univariate and multivariable analyses of CT visual assessment and binary slope for differentiation of invasive mucinous adenocarcinoma and bacterial pneumonia.</p

An example of margin-based analysis for obtaining the attenuation slope from lesion to normal lung in invasive mucinous adenocarcinoma.

<p>(A, B) Axial CT image shows an area of margin (red) selected for obtaining the attenuation transition from lesion to normal lung. (C) Pixels in the selected area in (B) were plotted as rectangular boxes with multiple pixels showing the attenuation transition from consolidation (left side) to normal lung (right side). (D) The graph shows the attenuation changes from consolidation (left side) to normal lung (right side) among one of the pixel lines (red box from C). (E) Average attenuation changes within the five pixels from the center of the highest slope in the selected area plotted from the consolidation (left side) to normal lung (right side). HU, Hounsfield unit.</p

Flowchart of patients.

<p>Flowchart of patients.</p

Receiver operating curves showing the diagnostic performance of the attenuation slope at the margin of lesions for differentiating between invasive mucinous adenocarcinoma and bacterial pneumonia manifesting as an air space consolidation.

<p>The C-indices for the graphs are 0.72–0.75, and the highest value is noted at the 7-pixel maximal slope. At a cut-off slope value of -154.21, sensitivity was 86.7% and specificity was 67.5% for the diagnosis of invasive mucinous adenocarcinoma using the 7-pixel maximal slope. max., maximal; avg., average.</p

CT visual assessment of invasive mucinous adenocarcinoma and bacterial pneumonia.

<p>CT visual assessment of invasive mucinous adenocarcinoma and bacterial pneumonia.</p

Univariate analysis of CT margin-based analysis for differentiation of invasive mucinous adenocarcinoma and bacterial pneumonia.

<p>Univariate analysis of CT margin-based analysis for differentiation of invasive mucinous adenocarcinoma and bacterial pneumonia.</p

Region of interests (ROIs) for CT texture analysis in a patient with invasive mucinous adenocarcinoma.

<p>CT images of 1-mm slice thickness with three round ROIs in a consolidative lesion. Histograms show the distributions of CT attenuation (HU, Hounsfield unit) of the ROIs on the horizontal axis. The vertical axis of the histograms shows the frequencies of attenuation of the lesion.</p

Clinical characteristics of patients with pathologically confirmed consolidative mucinous adenocarcinoma and bacterial pneumonia.

<p>Clinical characteristics of patients with pathologically confirmed consolidative mucinous adenocarcinoma and bacterial pneumonia.</p

Socio-demographic and clinical characteristics of the study participants.

<p>Socio-demographic and clinical characteristics of the study participants.</p