(21 days)
The FerriScan R2-MRI Analysis System is intended to measure liver iron concentration to aid in the identification and monitoring of non-transfusiondependent thalassemia patients receiving therapy with deferasirox.
The FerriScan R2-MRI Analysis System is a post-processing software tool that measures liver iron concentration based on the proton transverse relaxation rate (R2) of MRI images. R2 values are converted to liver iron concentration measurements using a calibration curve.
The FerriScan R2-MRI Analysis System is a post-processing software tool that measures liver iron concentration (LIC). It is intended to aid in the identification and monitoring of non-transfusion-dependent thalassemia (NTDT) patients receiving deferasirox therapy.
Here's an analysis of the acceptance criteria and the studies proving the device meets them:
1. Table of Acceptance Criteria and Reported Device Performance
The provided text excerpts do not explicitly list formal "acceptance criteria" with numerical thresholds for performance metrics. Instead, the document describes the required performance testing and the results of those tests, along with risks and mitigation measures that implicitly define acceptable performance. The key performance indicators evaluated are: Precision, Bias, Repeatability, Reproducibility, Sensitivity, and Specificity.
Therefore, the table below consolidates the relevant performance data from the provided text, indicating how the device performed against the implicitly required characteristics.
| Acceptance Criterion (Implicit from required performance testing and risk mitigation) | Reported Device Performance |
|---|---|
| Precision (agreement between replicate measurements) | - Calibration Study (105 patients): Average standard error of LIC by FerriScan: approx. 15%. |
- Validation Study (233 patients): Bland-Altman 95% limits of agreement: 74% and -71%. |
| Bias (systematic measurement error) | - Calibration Study (105 patients): Bland-Altman 95% limits of agreement with liver biopsy: -56% to 50% with bias of -3%. - Validation Study (233 patients): Bland-Altman 95% limits of agreement: 74% and -71% with a bias of 1.9%.
- Mean percentage differences in LIC between FerriScan and liver biopsy were not significantly different than zero in either study. |
| Repeatability (precision under same conditions over short period) | - 60 individuals tested twice: Standard deviation in R2 measurement: 8.1%. - Consistent with 7.7% random error from initial 10-patient calibration study. |
| Reproducibility (precision under different locations/operators) | - Phantom testing (K043271): Coefficient of variability across 13 different scanners: < 2.1%. |
| Sensitivity at various LIC thresholds (95% CI) | - 1.8 mg Fe/g dw: 94% (86-97) - 3.2 mg Fe/g dw: 94% (85-98)
- 7.0 mg Fe/g dw: 89% (79-95)
- 15 mg Fe/g dw: 85% (70-94) |
| Specificity at various LIC thresholds (95% CI) | - 1.8 mg Fe/g dw: 100% (88-100) - 3.2 mg Fe/g dw: 100% (91-100)
- 7.0 mg Fe/g dw: 96% (86-99)
- 15 mg Fe/g dw: 89% (83-96) |
| Acceptance testing of images prior to processing | Labeling specifies instructions (e.g., FerriScan Phantom Pack use, acquisition settings, visual inspection, motion assessment). |
| Data processing quality assurance protocols | Labeling describes protocols for phantom and patient image processing (e.g., ROI selection, noise assessment, motion correction). |
2. Sample Sizes and Data Provenance
- Test Sets (Clinical Studies for Precision and Bias):
- Calibration Study: 105 patients.
- Validation Study (subgroup from ESCALATOR trial): 233 patients.
- Repeatability Study: 60 individuals.
- Sensitivity/Specificity Study (from K043271): No specific number provided for the sensitivity/specificity calculation itself, but likely derived from the calibration study population.
- Data Provenance: The document does not explicitly state the country of origin for the patient data for these specific performance studies. However, the contact for the device is in Australia, and the deferasirox trials mentioned were likely international. The studies described are clinical studies, implying prospective data collection focused on the device's performance in patient populations, although the sensitivity/specificity study dates back to the original 510(k) (K043271), making it potentially a retrospective analysis of previously collected data.
3. Number of Experts and Qualifications for Ground Truth
The document does not specify the number or qualifications of experts used to establish the ground truth for the test sets.
4. Adjudication Method for the Test Set
The document does not describe any expert adjudication method (e.g., 2+1, 3+1) for the test sets.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No Multi-Reader Multi-Case (MRMC) comparative effectiveness study evaluating human readers with vs. without AI assistance is mentioned. The device is a "standalone" image post-processing system that provides a numerical LIC value, not an AI-assisted interpretation by a human reader.
6. Standalone Performance (Algorithm Only without Human-in-the-Loop)
Yes, standalone performance was done. The FerriScan R2-MRI Analysis System is described as a "post-processing software tool that measures liver iron concentration." The performance metrics (precision, bias, repeatability, reproducibility, sensitivity, specificity) are inherently measures of the algorithm's direct output (LIC value) compared to the ground truth. There is no mention of "human-in-the-loop" interaction for interpreting the R2-MRI calculation itself.
7. Type of Ground Truth Used
The primary ground truth used for assessing the device's performance (precision, bias, sensitivity, and specificity) was:
- Atomic absorption spectrometry from liver biopsy: This is considered the reference measurement of LIC.
8. Sample Size for the Training Set
The document does not explicitly state the sample size used for training the FerriScan R2-MRI Analysis System. The calibration study (105 patients) was used to "define an empirically-derived relationship" between R2 values and LIC, which implies it contributed to the creation or refinement of the calibration curve within the software. It's possible this study served as or contributed to the training data.
9. How the Ground Truth for the Training Set Was Established
Assuming the "calibration study" described (105 patients) contributed to establishing the relationship used within the software (effectively the "training" aspect for the calibration curve), the ground truth for this calibration was established using atomic absorption spectrometry from liver biopsy.
§ 892.1001 Liver iron concentration imaging companion diagnostic for deferasirox.
(a)
Identification. The liver iron concentration imaging companion diagnostic for deferasirox is an image processing device intended to aid in the identification and monitoring of non-transfusion-dependent thalassemia patients receiving therapy with deferasirox. The device calculates a numeric value for liver iron concentration based on magnetic resonance images acquired under controlled conditions. The calculated numeric value is used to assess the need for deferasirox treatment and for monitoring treatment in patients with non-transfusion-dependent thalassemia. The liver iron concentration imaging companion diagnostic for deferasirox is essential to the safe and effective use of deferasirox in patients with non-transfusion-dependent thalassemia.(b)
Classification. Class II (special controls). The special controls for this device are:(1) Design verification and validation must include nonclinical and clinical performance testing demonstrating the bias, precision, repeatability, and reproducibility of liver iron concentration measurements.
(2) Labeling must include specifying:
(i) Instructions for acceptance testing of images prior to processing;
(ii) Data processing quality assurance protocols; and
(iii) The sensitivity and specificity of liver iron concentration measurements.