(177 days)
Velacur is intended to provide estimates of tissue stiffness generated from shear wave speed measurements (40-70 Hz) and coefficient of attenuation. The device is indicated to non-invasively determine liver tissue stiffness and attenuation. These are meant to be used in conjunction with other clinical indicators in order to assist in clinical management of patients with liver disease.
Velacur is a portable device intended to non-invasively measure the stiffness and attenuation of the liver via measurement of liver tissue shear modulus and ultrasound attenuation. This is done by measuring the wavelength or wave speed of mechanically created shear waves within the organ of the patient. Attenuation is measured directly via the loss in power of the ultrasound beam.
The device is designed to be used at the point of care, in clinics and hospitals. The device is used by a medical profession, an employee of the clinic/hospital. The activation unit is placed under the patient, while lying supine on an exam bed. The activation unit vibrates causing shear waves within the liver of the patient. The ultrasound transducer is placed on the patient's skin, over the intercostal space, and is used to take volumetric scans of the liver while shear waves are occurring. From the scan data, the device calculates tissue stiffness and attenuation.
Here's a breakdown of the acceptance criteria and study details for the Velacur device, as extracted from the provided text:
Velacur Device Performance and Study Details
1. Acceptance Criteria and Reported Device Performance
| Acceptance Criteria | Reported Device Performance |
|---|---|
| Organ Segmentation Guide (for liver segmentation): | |
| Average Dice Score > 0.7 | Average Dice Score > 0.7 |
| Overall pixel-based accuracy > 80% | Overall pixel-based accuracy > 80% |
| Wave Quality Guide (for shear wave detection and segmentation): | |
| Dice Scores ≥ 0.7 | Dice Scores ≥ 0.7 |
| Sensitivity ≥ 80% | Sensitivity ≥ 80% |
| Specificity ≥ 80% | Specificity ≥ 80% |
2. Sample Size for Test Set and Data Provenance
- Test Set Sample Size: More than 1,500 images, from 35-40 patients.
- Data Provenance: Patient data from the US and Canada. The data was collected from sites in the US and Canada.
- Retrospective/Prospective: Not explicitly stated, but the description "Evaluation data was collected from volunteers and patients" suggests it was prospectively collected for evaluation.
3. Number of Experts for Ground Truth and Qualifications
- Organ Segmentation Guide:
- Number of Experts: At least three sonographers.
- Qualifications: All had more than 20 years of experience in abdominal ultrasound imaging.
- Wave Quality Guide:
- Number of Experts: Not specified beyond "all experts."
- Qualifications: All experts hold a masters or PhD in a relevant field and have at least 10 years of experience with ultrasound imaging and elastography.
4. Adjudication Method for Test Set
- Organ Segmentation Guide: Ground truth was established using a pixel-based voting method (implying the consensus of the three sonographers).
- Wave Quality Guide: Ground truth was established through expert consensus.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No information on a Multi-Reader Multi-Case (MRMC) comparative effectiveness study (i.e., comparing human readers with AI vs. without AI assistance) is provided in the document. The study focuses on the standalone performance of the AI algorithms.
6. Standalone (Algorithm Only) Performance
Yes, standalone (algorithm only) performance was done. The reported Dice Scores, pixel accuracy, sensitivity, and specificity are metrics of the algorithm's performance in segmenting organs and detecting/segmenting shear waves independently.
7. Type of Ground Truth Used
Expert consensus based on manual image segmentation.
8. Sample Size for Training Set
More than 5,000 patient images were used for training each algorithm.
9. How Ground Truth for Training Set Was Established
Not explicitly detailed for the training set, but it can be inferred that a similar process of manual image segmentation by experts was used, as described for the validation set. The text states: "Ground truth was established using manual image segmentation by experts in the field of sonography and/or ultrasound elastography," followed by details for both validation algorithms. It is reasonable to assume a similar method was employed for the training data's ground truth.
§ 892.1560 Ultrasonic pulsed echo imaging system.
(a)
Identification. An ultrasonic pulsed echo imaging system is a device intended to project a pulsed sound beam into body tissue to determine the depth or location of the tissue interfaces and to measure the duration of an acoustic pulse from the transmitter to the tissue interface and back to the receiver. This generic type of device may include signal analysis and display equipment, patient and equipment supports, component parts, and accessories.(b)
Classification. Class II (special controls). A biopsy needle guide kit intended for use with an ultrasonic pulsed echo imaging system only is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in § 892.9.