Need for accurate and scalable diagnostic tools
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MANUAL MICROSCOPY
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RAPID DIAGNOSTIC TEST (RDT)
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MOLECULAR TECHNIQUES (e.g. PCR)
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AUTOMATED MICROSCOPY - OCTOPI
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*Based on clinical data from recent study
Processing pipeline
- Consistent blood smearing with Inkwell, where each slide contains a monolayer of up to 13-16 million red blood cells (RBCs)
- Simple, quick and convenient staining using DAPI (fluorescent stain)
- High throughput scanning (> 500k RBCs/minute) and machine learning based segmentation and image classification
Procedure for applying Octopi to malaria diagnosis.
Real-time malaria detection
- Automated blood smear scanning and machine learning based red blood cell and malaria parasite quantification
- Identification and reporting of fluorescently labeled parasites (along with “parasite prediction score”) for convenient review and validation
- Image acquisition, cell segmentation and parasite classification completing in ~ 1 second per field of view (containing up to 8-10k RBCs)
High throughput imaging and analysis
- Monolayer of red blood cells and DAPI stained parasites covering most of the smeared area (unlike traditional thin smears with useful information in only the feathered edge)
- Analysis of millions of red blood cells in a single slide, i.e. orders of magnitude larger than traditional techniques, thus significantly improving the limit of detection for malaria microscopy
- Fluorescence microscopy (along with differential phase contrast imaging) enables larger field of view using 20× microscope objective, instead of 100× oil objective
Machine learning cellular-level performance
- ResNet-18 model with one round of retraining, resulting in false positives < 5 parasites/μL (average)
- Per-parasite level false negative rate < 8% in our test dataset
- Estimated limit of detection LoD ~ 12 parasites/μL for P. falciparum malaria parasites
Patient-level performance
- Independent dataset with 73 patient/donors and 190 blood smears (parasitemia for malaria positive patients ranging from 16 parasites/µL to around 130,000 parasites/µL)
- Sensitivity = 100% and specificity = 97.4% at parasite cut-off of 15 parasites/µL
- Sensitivity = 97.1% and specificity = 100% at parasite cut-off of 20 parasites/µL
