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The MolecuLight i:X is a handheld imaging tool that allows clinicians diagnosing and treating skin wounds, at the point of care, to

• View and digitally record images of a wound, (i)
• Measure and digitally record the size of a wound, and (ii)
• View and digitally record images of fluorescence emitted from a wound when exposed to an excitation light. (iii)

The fluorescence image, when used in combination with clinical signs and symptoms, has been shown to increase the likelihood that clinicians can identify wounds containing bacterial loads >104 CFU per gram as compared to examination of clinical signs and symptoms alone. The MolecuLight i:X device should not be used to rule-out the presence of bacteria in a wound.

The MolecuLight i:X does not diagnose or treat skin wounds.

The MolecuLight i:X Imaging Device is a handheld medical imaging device comprised of a high-resolution color LCD display and touch-sensitive screen with integrated optical and microelectronic components. Moleculight i:X uses its patented technology to enable real-time standard digital imaging and fluorescence imaging in wounds and surrounding healthy skin of patients as well as wound area measurements.

Here's a breakdown of the acceptance criteria and the study that proves the MolecuLight i:X device meets them, based on the provided FDA 510(k) summary:

1. Table of Acceptance Criteria and Reported Device Performance

The core clinical claim for the MolecuLight i:X related to bacterial identification is: "The fluorescence image, when used in combination with clinical signs and symptoms, has been shown to increase the likelihood that clinicians can identify wounds containing bacterial loads >10^4 CFU per gram as compared to examination of clinical signs and symptoms alone."

While the document doesn't explicitly state quantitative acceptance criteria in the "we will achieve X performance" format, the demonstrated performance serves as the evidence for meeting their stated claim. The crucial part of the performance is the improvement in identifying wounds with relevant bacterial loads.

Acceptance Criteria (Implied by Clinical Claim and Study Results)

^1 The document states: "The use of the MolecuLight i:X in combination with clinical signs and symptoms resulted in a <10% increase as compared to CSS alone in the rate in wounds that were incorrectly identified as having bacterial load >10^4 CFU/g, whose resulting bacterial load determined by conventional microbiological analysis was <10^4 CFU/q." This is a specific claim about the false positive rate.

2. Sample Size and Data Provenance

• Sample Size for Test Set: n = 350 wound sites (referred to as "All patients")
  • Microbiology Positive (>10^4 CFU/g): n = 287
  • Microbiology Negative (<10^4 CFU/g): n = 63
• Data Provenance: The document does not specify the country of origin. It indicates it was a "clinical study," implying prospective data collection for this purpose.

3. Number of Experts and Qualifications for Ground Truth

• The document mentions "clinicians" evaluating clinical signs and symptoms (CSS) and then interpreting MolecuLight i:X fluorescence images. However, it does not specify the number or qualifications of these clinicians related to establishing the clinical ground truth for the test set.
• The primary ground truth for bacterial load (>10^4 CFU/g) was "quantitative microbiological analysis," which is a lab-based, objective method, not dependent on expert consensus.

4. Adjudication Method for the Test Set

• The document does not describe an adjudication method for the clinical evaluation of CSS or the interpretation of MolecuLight i:X images. It compares these clinical assessments directly against the quantitative microbiological analysis. This suggests that individual clinicians' interpretations were the data points, rather than a consensus interpretation.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

• A formal MRMC study is not explicitly mentioned as having been performed. The study evaluates the likelihood that clinicians can identify wounds, comparing performance with and without the device. While it involves multiple clinicians, it's presented as a direct comparison of the combined CSS+iX approach versus CSS alone, rather than a statistical comparison of reader performance improvement.
• Effect Size:
  • The sensitivity for identifying high bacterial loads increased from 15.33% (CSS alone) to 60.98% (CSS + iX). This is a substantial increase, making the device significantly more likely to flag relevant wounds.
  • The specificity decreased from 93.65% (CSS alone) to 84.13% (CSS + iX). This indicates a trade-off where more wounds were incorrectly identified as having high bacterial loads with the device, but the report explicitly states this increase in false positives was "<10%".

6. Standalone Performance (Algorithm Only)

• Not applicable/Not done. The MolecuLight i:X is described as a "handheld imaging tool" used by "clinicians." Its function is to provide an image that clinicians interpret. It is not an AI/algorithm that provides a standalone diagnosis or classification. The "performance" reported is the combination of the device's output and human interpretation ("clinician's interpretation of the MolecuLight i:X fluorescence image and CSS").

7. Type of Ground Truth Used

• The primary ground truth for validation of the bacterial load identification claim was quantitative microbiological analysis (i.e., bacterial culture results defining >10^4 CFU per gram). This is an objective and laboratory-confirmed ground truth, considered a strong reference standard for bacterial burden.

8. Sample Size for the Training Set

• The document does not specify a separate training set or its size. This is typical for a medical device that provides direct imaging for human interpretation, rather than a machine learning algorithm that is "trained" on data. The clinical study described here functions as the pivotal performance validation.

9. How Ground Truth for the Training Set was Established

• As no separate training set or AI/ML training is indicated, this point is not applicable. The ground truth for the clinical study was established by quantitative microbiological analysis of wound samples.

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