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icobrain aria is a computer-assisted detection (CADe) and diagnosis (CADx) software device to be used as a concurrent reading aid to help trained radiologists in the detection, assessment and characterization of Amyloid Related Imaging Abnormalities (ARIA) from a set of brain MR images. The software provides information about the presence, location, size, severity and changes of ARIA-E (brain edema or sulcal effusions) and ARIA-H (hemosiderin deposition, including microhemorrhage and superficial siderosis). Patient management decisions should not be made solely on the basis of analysis by icobrain aria.

icobrain aria is a software-only device for assisting radiologists with the detection of amyloid-related imaging abnormalities (ARIA) on brain MRI scans of Alzheimer's disease patients under an amyloid beta-directed antibody therapy. The device utilizes 2D fluid-attenuated inversion recovery (FLAR) for the detection of ARIA-E (edema/sulcal effusion) and 2D T2* gradient echo (T2*-GRE) for the detection of ARIA-H (hemosiderin deposition).

icobrain aria automatically processes input brain MRI scans in DICOM format from two time points and generates annotated DICOM images and an electronic report.

Here's a summary of the acceptance criteria and study that proves the device meets them, based on the provided text:

icobrain aria: Acceptance Criteria and Performance Study Summary

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria are not explicitly listed in a single, dedicated table with pass/fail thresholds. Instead, they are implicitly defined by the statistically significant improvements demonstrated in the clinical (MRMC) study, and the "in line with human experts" conclusion from standalone performance. The document focuses on showing the effect size of the improvement rather than pre-defined absolute thresholds for sensitivity, specificity, or AUC for human-AI combined performance. For standalone metrics, it reports specific values and concludes they are "in line with the performance of human experts," suggesting the internal acceptance criteria were met.

Therefore, the table below will summarize the reported performance results from the clinical study, which implicitly met the acceptance criteria by demonstrating significant improvement over unassisted reading.

2. Sample Size Used for the Test Set and Data Provenance

• Test Set Sample Size: 199 cases.
• Data Provenance: MRI datasets from subjects diagnosed with Alzheimer's disease. To guarantee independence, test data subjects were not included in the training set.
  • Country of Origin: More than 100 sites in 20 countries. Approximately half the data originated from the US and the other half from outside the US.
  • Retrospective/Prospective: The study used retrospective data from clinical trials (aducanumab clinical trials PRIME (NCT02677572), EMERGE (NCT02484547), and ENGAGE (NCT02477800)). This data provenance applies to both training and testing datasets.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications

• Number of Experts: A consensus of 3 experts was used for the clinical (MRMC) study ground truth. For standalone testing, the ground truth was established by unspecified "expert neuroradiologists."
• Qualifications of Experts:
  • Clinical Study (MRMC): Experts who performed "safety ARIA reading in clinical trials for Aβ-directed antibody therapies in AD."
  • Standalone Testing: "expert neuroradiologists (with experience performing safety ARIA reading in clinical trials for Aβ-directed antibody therapies in AD) manually segmented both ARIA-H findings." This indicates they had prior, relevant experience.

4. Adjudication Method for the Test Set

• Adjudication Method: "A consensus of 3 experts" was used to establish the ground truth for the clinical (MRMC) study. The specific consensus method (e.g., majority vote, discussion to agreement) is not detailed, but the term "consensus" implies a collective agreement process.

5. If a Multi Reader Multi Case (MRMC) Comparative Effectiveness Study was Done, and Effect Size of Improvement

• MRMC Study Done: Yes, a fully-crossed MRMC retrospective reader study was conducted.
• Effect Size (AUC difference, Assisted vs. Unassisted):
  • ARIA-E Detection: +0.051 AUC (95% CI [0.020, 0.083]), p=0.001
  • Pooled ARIA-H Detection: +0.044 AUC (95% CI [0.017, 0.070]), p=0.001
  • ARIA-H Microhemorrhages: +0.029 AUC (95% CI [0.002, 0.055]), p=0.032
  • ARIA-H Superficial Siderosis: +0.063 AUC (95% CI [0.023, 0.102]), p=0.003

Readers also showed significant increases in sensitivity, significant decreases in inter-reader variability, and were on average faster when assisted.

6. If a Standalone (i.e. Algorithm only without human-in-the-loop performance) was Done

• Standalone Study Done: Yes, "icometrix conducted standalone performance assessments."
  • Standalone Performance Highlights (Main Test Set on 199 cases):
    • ARIA-E Diagnosis: Sensitivity 0.94, Specificity 0.67, AUC 0.84
    • ARIA-H Diagnosis: Sensitivity 0.87, Specificity 0.66, AUC 0.81
    • ARIA-E Finding-level: True Positive Rate 69.1%, False Positive findings per case 0.7
    • ARIA-H New Microhemorrhages Finding-level: True Positive Rate 66.1%, False Positive findings per case 0.9
    • ARIA-H New Superficial Siderosis Finding-level: True Positive Rate 62.5%, False Positive findings per case 0.1
  • The document concludes that standalone performance was "in line with the performance of human experts."

7. The Type of Ground Truth Used

• Ground Truth Type: Expert consensus for the clinical study (MRMC) and expert manual annotations for the standalone testing.
  • Details: For standalone testing, "expert neuroradiologists ... manually segmented both ARIA-E and ARIA-H findings. Ground truth ARIA measurements were derived from the expert manual annotated masks." For the MRMC study, ground truth was obtained via "a consensus of 3 experts."

8. The Sample Size for the Training Set

• Training Set Sample Size:
  • FLAIR images (for ARIA-E): 475 image pairs from 172 subjects.
  • T2-GRE images (for ARIA-H):* 326 image pairs from 177 subjects.

9. How the Ground Truth for the Training Set Was Established

• Ground Truth Establishment for Training Set: The data used for developing the algorithms "have been manually annotated by expert neuroradiologists with prior experience of reading ARIA in clinical trials of amyloid beta-directed antibody drugs." This implies manual annotation by experts served as the ground truth for training.

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