Role of radiomics in predicting lung cancer spread through air spaces in a heterogeneous dataset

Abstract

Background: Spread through air spaces (STAS) has been reported as a negative prognostic factor in patients with lung cancer undergoing sublobar resection. Radiomics has been recently proposed to predict STAS using preoperative computed tomography (CT). However, limitations of previous studies included the strict selection of imaging acquisition protocols, leading to results hardly applicable to daily clinical practice. The aim of this study is to test a radiomics-based prediction model of STAS in a practice-based dataset.

Methods: A training cohort of 99 consecutive patients (65 STAS+ and 34 STAS-) with resected lung adenocarcinoma (ADC) was retrospectively collected. Preoperative CT images were collected from different centers regardless model and scanner manufacture, acquisition and reconstruction protocol, contrast phase and pixel size. Radiomics features were selected according to separation power and P value stability within different preprocessing setups and bootstrapping resampling. A prospective cohort of 50 patients (33 STAS+ and 17 STAS-) was enrolled for the external validation.

Results: Only the five features with the highest stability were considered for the prediction model building. Radiomics, radiological and mixed radiomics-radiological prediction models were created, showing an accuracy of 0.66±0.02 after internal validation and reaching an accuracy of 0.78 in the external validation.

Conclusions: Radiomics-based prediction models of STAS may be useful to properly plan surgical treatment and avoid oncological ineffective sublobar resections. This study supports a possible application of radiomics-based models on data with high variance in acquisition, reconstruction and preprocessing, opening a new chance for the use of radiomics in the prediction of STAS.

Trial registration: ClinicalTrials.gov identifier: NCT04893200.

Keywords: Radiomics; lung cancer; machine learning; spread through air space (STAS).

Figure 1

Study flowchart. Accuracy in internal validation is reported as mean ±2 standard deviation. ROI, region of interest; Ac, accuracy; SE, sensibility; SP, specificity.

Figure 2

ROC curves for the radiomics predictor (black), radiological predictor (green) and mixed predictor (blue) after external validation. The AUC for the models is 0.66, 0.72 and 0.79 respectively. AUC, area under the curve; ROC, receiver operating characteristics.

Figure 3

Images after wavelet transform. The same computed tomography scan slide is reported after has been filtered for edge enhancement (wavelet transformation). (A) Original image; (B) image after L in both vertical and horizontal directions; (C) image after L in horizontal direction and H in vertical direction; (D) image after H in horizontal and L in vertical direction; (E) image after H in both directions. L, low pass filter; H, high pass filter.