Pre-trained convolutional neural networks as feature extractors toward improved malaria parasite detection in thin blood smear images

TLDR

Malaria, transmitted by Anopheles mosquitoes, is diagnosed via microscopic examination of blood smears, but accuracy depends on smear quality and expert interpretation, making large‑scale screening difficult and motivating the use of deep learning for automated, scalable analysis. The study aims to evaluate pre‑trained CNNs as feature extractors for classifying parasitized and uninfected cells to improve malaria screening. The authors experimentally identify the optimal CNN layers for feature extraction from blood smear images. Statistical validation shows that pre‑trained CNNs provide promising feature extraction for malaria cell classification.

Abstract

Malaria is a blood disease caused by the Plasmodium parasites transmitted through the bite of female Anopheles mosquito. Microscopists commonly examine thick and thin blood smears to diagnose disease and compute parasitemia. However, their accuracy depends on smear quality and expertise in classifying and counting parasitized and uninfected cells. Such an examination could be arduous for large-scale diagnoses resulting in poor quality. State-of-the-art image-analysis based computer-aided diagnosis (CADx) methods using machine learning (ML) techniques, applied to microscopic images of the smears using hand-engineered features demand expertise in analyzing morphological, textural, and positional variations of the region of interest (ROI). In contrast, Convolutional Neural Networks (CNN), a class of deep learning (DL) models promise highly scalable and superior results with end-to-end feature extraction and classification. Automated malaria screening using DL techniques could, therefore, serve as an effective diagnostic aid. In this study, we evaluate the performance of pre-trained CNN based DL models as feature extractors toward classifying parasitized and uninfected cells to aid in improved disease screening. We experimentally determine the optimal model layers for feature extraction from the underlying data. Statistical validation of the results demonstrates the use of pre-trained CNNs as a promising tool for feature extraction for this purpose.