Ensemble performance for nasogastric tube (NGT) malposition detection on
the testing set (355 images). (A) Scatterplot shows
two-dimensional twin neural network (Ivis) embedding of the combined
global average pooling layer values in the NGT malposition ensemble.
Each point represents a single chest radiograph in the testing set.
Green, orange, and red points reflect satisfactory, malpositioned, and
bronchial NGT ground truth values, respectively. (B)
Heatmap shows gradient-weighted class activation mapping activation of
the final convolutional layer in the 1024 × 1024 InceptionV3
model superimposed over a bronchial-positioned NGT. (C)
Ensemble confusion matrix between ground truths and predicted image
labels. Predicted labels reflect the class with the greatest
classification probability. (D–F) Receiver operating
characteristic curves for each class of interest. Shaded areas are 95%
CIs, generated using 2000 bootstrapped samples. AP = anteroposterior,
AUC = area under the receiver operating characteristic curve.