(219 days)
The QT Scanner 2000 Model A is for use as an ultrasonic imaging system to provide reflectionmode and transmission-mode images of a patient's breast. The device is not intended to be used as a replacement for screening mammography.
The QT Scanner 2000 Model A ("QT Scanner") is an automated, software-controlled ultrasound imaging system which performs a standardized scan of the whole breast without the use of ionizing radiation, compression, or contrast injection; and generates both reflection-mode and transmission-mode breast images. The QT Scanner consists of a Patient Scanning System, an Operator Console, an optional offboard image processor, and the QTviewer software.
The Patient Scanning System contains the necessary electronics which perform acquisition and initial processing of the breast images and further provides a support table which allows the patient to rest comfortably while the scanning takes place. The scan tank is centered below a patient's breast and contains the ultrasound transducer arrays. The transducer arrays include a set of three reflection transducers that transmit pulsed ultrasound plane waves into targeted tissues using the water bath in the scan tank as a coupling medium. An additional transmitter and receiver array pair collect the ultrasound energy to provide speed of sound values.
During scanning, a patient lies prone on the examination table with the breast suspended in a warm water bath maintained near skin temperature. Images are automatically acquired on a pendant breast positioned with the nipple as a point of reference. The transducer arrays rotate about a vertical axis to circle the breast in the coronal plane. The array is then translated vertically, and the scanning process is repeated until the entire breast is scanned, allowing B-scan images to be constructively combined into tomographic, speed of sound and reflection ultrasound images.
The QT Scanner outputs the images to a server which allows the images to be stored until they are reviewed on a Viewer Console running the OTviewer™ software. Alternatively, raw data files can be output to a server and remotely constructively combined into tomographic, speed of sound and reflection ultrasound images. Coronal, axial and sagittal images are generated for review by the radiologist. The QTviewer software also provides a number of analytics capabilities, such as biometric measurement, manual segmentation, and Region of Interest calculations.
The provided text describes two clinical studies that support the substantial equivalence of the QT Scanner 2000 Model A to its predicate device. Both studies evaluate features of the device's software.
Here's a breakdown of the requested information:
1. Table of Acceptance Criteria and Reported Device Performance
The FDA clearance document does not explicitly state quantitative acceptance criteria in the typical format (e.g., AUC > X, Sensitivity > Y). Instead, it describes performance in comparative terms. The acceptance criteria appear to be based on demonstrating superiority or non-inferiority compared to the default processing method, as interpreted and evaluated by expert radiologists.
| Feature Evaluated | Acceptance Criteria (Implicit) | Reported Device Performance |
|---|---|---|
| Implant Processing | Superior overall interpretability of breast with silicone implant images, superior visualization of implant-specific anatomical features, and non-inferior visualization of general anatomical features compared to default processing. | Achieved: Superior overall interpretability of breast with silicone implant images, superior visualization of implant center and implant-tissue interface, and non-inferior visualization of general anatomical features (e.g., nipple, skin). |
| Transmission- and Reflection-mode Reprocessing | Superior overall visualization of both speed-of-sound and reflection images, and at least non-inferior visualization of all relevant anatomical features compared to default processing. | Achieved: Superior overall visualization of both speed-of-sound and reflection images, and at least non-inferior visualization of all relevant anatomical features. |
2. Sample Size Used for the Test Set and Data Provenance
- Study 1 (Implant Processing): 25 breast with silicone implant images.
- Study 2 (Transmission- and Reflection-mode Reprocessing): 25 challenging-case breast images (13 dense breasts and 12 fatty breasts).
- Data Provenance: Both studies used "previously-acquired QT Ultrasound breast images," indicating a retrospective data collection. The country of origin is not specified.
3. Number of Experts Used to Establish Ground Truth for the Test Set and Qualifications
- Number of Experts: Three (3) expert radiologists for each study.
- Qualifications: Referred to simply as "expert radiologists." No further details on their experience (e.g., years of experience, sub-specialty) are provided in this document.
4. Adjudication Method for the Test Set
The document states that "three (3) expert radiologists independently reviewed" the images. The images were reviewed "in a blinded manner" and "comparatively evaluated." This suggests an independent review process, but it does not specify an adjudication method like 2+1 or 3+1 for resolving discrepancies. The reported performance implies a consensus or agreement was reached, or that individual findings were statistically aggregated, but the exact method isn't detailed.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done, and Effect Size
These studies were multi-reader multi-case (MRMC) studies, as they involved multiple expert readers evaluating multiple cases.
- Effect Size: The document describes the effect qualitatively (e.g., "superior overall interpretability," "non-inferior visualization") rather than providing specific quantitative effect sizes (e.g., percentage improvement in detection rate, change in diagnostic accuracy metrics).
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
No, these studies primarily evaluated the effect of the software's processing features on human interpretation. The experts reviewed the images generated by the different processing methods to assess interpretability and visualization. This is not a standalone algorithm performance evaluation where the algorithm makes a diagnosis without human input.
7. The Type of Ground Truth Used
The "ground truth" for assessing the interpretability and visualization of the images was based on expert visual grade analysis by three independent expert radiologists. This is a form of expert consensus or subjective expert evaluation of image quality and feature visualization, rather than an objective "ground truth" like pathology results or outcomes data that define the presence or absence of a disease.
8. The Sample Size for the Training Set
The document does not provide information on the sample size used for the training set for the software algorithms. The clinical studies described are performance evaluations of the software output using retrospective test sets.
9. How the Ground Truth for the Training Set Was Established
Since information on the training set and its size is not provided, how its ground truth was established is also not specified in this document.
§ 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.