Physiological Waveform Interpretation via Grad-CAM Heatmaps

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Solution Overview

Problem

Deep learning models used for interpreting physiological information, such as electrocardiograms, face challenges in providing a clear basis for prediction results, leading to ambiguity in medical determinations.

Innovation Solution

A device and method utilizing a convolutional neural network to classify waveform data into classes, with an importance specification unit applying Grad-CAM to highlight features contributing to predictions, and an output unit displaying indicators of importance alongside the measurement waveform, enabling users to interpret and verify the determination results.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If deep learning models are used to process physiological information, then prediction accuracy is improved, but interpretability deteriorates

Engineering Contradiction:
Improveprediction accuracyVSAvoidinterpretability
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

The patent introduces Grad-CAM as an intermediary technique that bridges the deep learning model and the user. It generates visual heatmaps that mediate between the internal complex computations of the CNN and the human need for interpretable explanations, showing which regions of the input waveform contribute most to the prediction without requiring users to understand the model's internal mechanics

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies color-coded visual indicators (heatmaps) to represent the importance of different waveform regions. Different colors indicate varying levels of contribution to the prediction, transforming abstract model decisions into visually intuitive information that enhances interpretability while maintaining prediction accuracy

Inventive Principle:
Principle #32Color changes

2Reliability

If complex deep learning models are deployed, then prediction capability is improved, but device complexity increases

Engineering Contradiction:
Improveprediction capabilityVSAvoidmodel complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the complex deep learning system into distinct functional modules: the CNN prediction unit for accurate classification, the Grad-CAM importance specification unit for generating explanations, and the visualization unit for displaying results. This modular segmentation allows each component to be optimized independently while maintaining overall system reliability

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The Grad-CAM module serves as an intermediary layer that translates complex model predictions into simple visual explanations without requiring changes to the underlying complex model architecture, thus maintaining prediction capability while reducing the perceived complexity for end users

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentUS12260962B2Physiological information acquisition device, processing device, and recording medium
Publication Date: 2025.03.25 NIHON KOHDEN CORP
  • US12260962B2 patent drawing
  • US12260962B2 patent drawing
  • US12260962B2 patent drawing

AI summary

A physiological information acquisition device configured to acquire physiological information of a subject includes: an input interface configured to receive waveform data corresponding to a measurement waveform of the physiological information from a sensor; a prediction unit configured to extract a feature from the waveform data using a convolutional neural network and predict a probability of the waveform data being classified into each of a plurality of classes; an importance specification unit configured to specify an importance of the feature with respect to a prediction result of the probability for at least one of the plurality of classes; and an output unit configured to output an indicator indicating the importance together with the measurement waveform.