(520 days)
HepaFat-Scan is a software device intended for quantitative measurement of the triglyceride fat fraction in magnetic resonance images of the liver. It utilises magnetic resonance images that exploit the difference in resonance frequencies between hydrogen nuclei in water and triglyceride fat. The quantitative triglyceride fat fraction is based on the measurement of a magnetic resonance parameter that reflects the ratio of the proton density signal of triglyceride fat to the total proton density signal in the liver.
When interpreted by a trained physician, the results provide information that can aid in diagnosis.
Standalone software application to facilitate the import visualization of multi-slice, gradient-echo MRI encompassing the abdomen, with functionality independent of the MRI equipment, to provide objective and reproducible determination of the triglyceride fat fraction in magnetic resonance images of the liver. It utilises magnetic resonance images that exploit the difference in resonance frequencies between hydrogen nuclei in water and triglyceride fat. The quantitative triglyceride fat fraction is based on the measurement of a magnetic resonance parameter that reflects the ratio of the proton density signal of triglyceride fat to the total proton density signal in the liver.
Here's an analysis of the HepaFat-Scan device, outlining its acceptance criteria and the study used for validation, based on the provided text:
HepaFat-Scan Acceptance Criteria and Validation Study
The provided 510(k) summary for HepaFat-Scan focuses on demonstrating substantial equivalence to existing predicate devices, rather than establishing specific quantitative acceptance criteria in the traditional sense of a performance study with defined thresholds for sensitivity, specificity, etc. The primary acceptance criterion here is "acceptable agreement" with a recognized ground truth method across a clinically relevant range.
1. Table of Acceptance Criteria and Reported Device Performance
| Acceptance Criteria (Implied) | Reported Device Performance |
|---|---|
| Acceptable agreement between HepaFat-Scan output and volumetric fat fraction from liver biopsy samples. | "Acceptable agreement was attained when comparing the liver biopsy volumetric fat fraction measurements to the HepaFat-Scan device output over a clinically wide range of liver fat fractions." |
| Equivalence between different MRI scanner models. | Demonstrated through a phantom study. |
Note: The document does not specify numerical thresholds (e.g., correlation coefficients, mean absolute error limits) for "acceptable agreement." This is common in substantial equivalence claims where the goal is to show the new device performs similarly to established methods, rather than surpassing a specific, pre-defined performance metric.
2. Sample Size Used for the Test Set and Data Provenance
- Test Set Sample Size: Not explicitly stated. The document refers to "in-vivo human clinical studies" where volumetric fat fractions were determined from liver biopsy samples. The exact number of patients or biopsy samples is not provided.
- Data Provenance: "in-vivo human clinical studies." The country of origin is not specified, but the applicant's address is Australia, suggesting the studies could have been conducted there. The studies were likely retrospective or a combination of retrospective and prospective, as biopsy data is often collected as part of routine patient care.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications
- Number of Experts: Not explicitly stated.
- Qualifications of Experts: Not explicitly stated, however, the ground truth was established by determining "volumetric fat fractions from liver biopsy samples... using a stereological method based on the Delesse principle." This implies the involvement of pathologists or trained laboratory technicians skilled in histopathology and stereological analysis.
4. Adjudication Method for the Test Set
- Adjudication Method: Not explicitly mentioned. Since the ground truth involved a quantitative stereological method on biopsy samples, it's less likely to involve a consensus-based adjudication process typical of qualitative image interpretations. The "agreement" was likely a direct comparison of the HepaFat-Scan's quantitative output against the quantitative biopsy-derived fat fraction.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
- MRMC Study: No, a multi-reader multi-case (MRMC) comparative effectiveness study was not conducted in the context of human readers improving with AI assistance. The study focused on the standalone performance of the HepaFat-Scan software compared to biopsy, not on its impact on human interpretation.
6. Standalone Performance (Algorithm Only without Human-in-the-loop Performance)
- Standalone Performance: Yes, a standalone performance study was conducted. The HepaFat-Scan is described as a "Standalone software application," and its "Accuracy and reproducibility of the quantification of the triglyceride fat fraction has been demonstrated through a combination of bench testing and in-vivo human clinical studies." This indicates the algorithm's output was directly compared to the ground truth.
7. Type of Ground Truth Used
- Type of Ground Truth: The primary ground truth for the in-vivo human clinical studies was pathology-derived data. Specifically, "Volumetric fat fractions were determined from liver biopsy samples... using a stereological method based on the Delesse principle, which directly measures volumetric fat fraction."
8. Sample Size for the Training Set
- Training Set Sample Size: Not provided. The document describes the validation study (test set) but does not disclose information about the training data used to develop the HepaFat-Scan algorithm.
9. How the Ground Truth for the Training Set Was Established
- Ground Truth for Training Set: Not provided. The document focuses exclusively on the validation study and its ground truth. Information on how the algorithm was developed or trained, including the ground truth used for that process, is not included in this summary.
§ 892.1000 Magnetic resonance diagnostic device.
(a)
Identification. A magnetic resonance diagnostic device is intended for general diagnostic use to present images which reflect the spatial distribution and/or magnetic resonance spectra which reflect frequency and distribution of nuclei exhibiting nuclear magnetic resonance. Other physical parameters derived from the images and/or spectra may also be produced. The device includes hydrogen-1 (proton) imaging, sodium-23 imaging, hydrogen-1 spectroscopy, phosphorus-31 spectroscopy, and chemical shift imaging (preserving simultaneous frequency and spatial information).(b)
Classification. Class II (special controls). A magnetic resonance imaging disposable kit intended for use with a magnetic resonance diagnostic device only is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in § 892.9.