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The Aspen Ultrasound System with the FreeStyle option provides B-mode images of anatomy in a field of view that extends well beyond a conventional B-mode region of interest. The FreeStyle option can also provide qualitative Color flow information in this extended field of view. The indications for use for each transducer operating with the FreeStyle feature are unchanged and include fetal, small organ, peripheral vessel, abdominal, gynecologic, transrectal, intraoperative, and musculoskeletal uses.

Device Description

The Aspen Ultrasound System with the FreeStyle feature is a modification of the Aspen Ultrasound System previously cleared as Model 2001, K934915/S1. The FreeStyle feature allows visualization of anatomy over a wider field of view that surrounds a particular region of interest. The feature operates in B-mode and Color Doppler modes for transducers that have been previously cleared by FDA for all indications for use except cardiac, opthalmic, and transcranial uses.

The FreeStyle feature operates by collecting a series of B-mode or Color Doppler image frames in real time, storing them, and then forming a larger composite image for display. The composite image can be displayed within seconds of the real time image frame captures or can be stored and displayed at a later time, perhaps at a Picture Archiving and Communications (PACS) review station. The frames can be captured over a 70cm linear distance or less.

The process is executed by a Pentium II or III based PC running Windows NT that is cabled to the ultrasound system and which resides on a shelf in the ultrasound system console. The hardware and software of the ultrasound system itself has not been modified except to add keyboard strokes the enables the Freestyle option and transfers control between the PC and ultrasound system. The PC has been programmed to store the B mode and Color Doppler image frames captured by the ultrasound system in DICOM format, to perform 2 dimensional motion analysis to determine frame to frame translation and rotation vectors, and to form the composite extended image using a graphics library function, and to transfer the extended image back to the ultrasound system for display or storage.

There is also a caliper measurement capability in the PC software that can be used on the B mode extended images to perform distance and length measurements. The Color Doppler extended images are used to detect the presence or absence of blood flow and are not for quantification.

AI/ML Overview

The provided text is a 510(k) summary for the Acuson Aspen™ Ultrasound System with FreeStyle™ Imaging Option. This document describes the device, its intended use, warnings, and precautions, but it does not contain explicit acceptance criteria or a detailed study section that directly proves the device meets specific performance criteria with reported metrics.

Instead, the document states, "Clinical data was obtained to show the efficacy of FreeStyle images. They are contained in the 510k and were reviewed by FDA." This suggests that a separate document within the 510(k) submission provided the detailed performance data, but this information is not included in the provided text.

Based on the available information, I can only provide general acceptance criteria inferred from the "Warnings and Precautions" and the fact that the device received 510(k) clearance, implying it met the FDA's requirements for substantial equivalence.

Here's an attempt to structure the information, with caveats due to the lack of explicit performance data:

Acceptance Criteria and Device Performance (Inferred)

Since specific numerical acceptance criteria and reported performance metrics are not provided in the summary, the table below is based on the implied performance expectations and warnings outlined in the document. The "Reported Device Performance" column reflects that the device was cleared by the FDA, suggesting these general criteria were met.

1. Table of Acceptance Criteria and Reported Device Performance

Acceptance Criteria Category	Acceptance Criteria (Inferred from Warnings/Precautions)	Reported Device Performance
Image Quality	Image quality should be sufficient for diagnostic purposes and free from significant artifacts.	The device provides "B-mode images of anatomy in a field of view that extends well beyond a conventional B-mode region of interest" and "qualitative Color flow information." The 510(k) clearance implies that the imaging performance for its indications of use was found acceptable by the FDA, under the condition that users are aware of potential artifacts and their impact on image quality as outlined in the warnings.
Artifact Management	User must be able to identify and determine if artifactual characteristics (obvious linear discontinuity, excess shadowing, ill-defined anatomy, jagged skin line) exist. If present, quality is suspect and reacquisition may be required.	The device's labeling includes warnings to guide users in identifying artifacts (e.g., obvious linear discontinuity, excess shadowing, ill-defined anatomy, jagged skin line) that could compromise image quality. The system is designed to allow clinical interpretation, and the responsibility for determining image quality and potential reacquisition rests with the trained sonographer or physician.
Measurement Accuracy	Caliper measurements on B-mode extended images should be reliable and accurate for diagnosis when the reconstructed image is free from acquisition-related artifacts.	The device offers caliper measurement capability on B-mode extended images for distance and length measurements. The labeling provides warnings about potential sources of error (e.g., wrong B-mode slice, non-planar acquisition) and emphasizes that measurements should only be made on well-reconstructed images. The FDA clearance suggests that, when used as instructed and with clinical judgment, the measurement capability is deemed acceptable for qualitative assessments (for Color Doppler) and quantitative (for B-mode) within its intended use. "When it is possible to make a measurement on a single acquired image frame, then that is preferable."
Safety	Minimization of misdiagnosis caused by inaccurate measurements and calculations on poorly reconstructed images.	The primary potential adverse effect is misdiagnosis due to poorly reconstructed images or inaccurate measurements. This risk is mitigated through comprehensive warnings in the labeling and implied requirement for adequate user training, as accepted by the FDA for market clearance.
Functionality	The FreeStyle option should provide extended field of view images in B-mode and Color Doppler modes as described.	The FreeStyle option collects and composites real-time B-mode or Color Doppler image frames to form a larger composite image for display, extending the field of view up to 70cm linear distance. This core functionality is central to the device's design and was cleared by the FDA for various transducers and clinical applications (fetal, small organ, peripheral vessel, abdominal, gynecologic, transrectal, intraoperative, musculoskeletal).

2. Sample Size Used for the Test Set and Data Provenance

The document states: "Clinical data was obtained to show the efficacy of FreeStyle images. They are contained in the 510k and were reviewed by FDA."

Sample Size: Not specified in the provided text.
Data Provenance: Not specified in the provided text (e.g., country of origin, retrospective or prospective).

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications

This information is not provided in the summary. The "Warnings and Precautions" section heavily relies on the "trained sonographer or physician's judgment" for determining image quality and the presence of artifacts, suggesting that clinical expertise is paramount in the operational use of the device.

4. Adjudication Method for the Test Set

The adjudication method is not specified in the provided text.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done

Not explicitly stated. The document focuses on demonstrating the efficacy of the FreeStyle images themselves rather than comparing performance with and without AI assistance (the FreeStyle option is described as a feature of the ultrasound system, not explicitly as an AI system in the modern sense, though it involves image processing). Therefore, no effect size of human readers improving with AI vs. without AI assistance is mentioned.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) was done

Not explicitly stated, but given the nature of the device (an ultrasound system with an imaging option) and the emphasis on user judgment for image interpretation and measurements, it is highly probable that performance was evaluated in the context of human use. The "Warnings and Precautions" explicitly highlight the user's role in assessing image quality and measurement reliability.

7. The Type of Ground Truth Used

The type of ground truth used is not specified in the provided text beyond "Clinical data was obtained to show the efficacy of FreeStyle images." Given the context of a diagnostic ultrasound system, ground truth would typically be established through clinical findings, patient outcomes, or comparison with other established imaging modalities, interpreted by clinicians.

8. The Sample Size for the Training Set

The document does not describe the development or training of an algorithm in the contemporary sense of machine learning, so a "training set" is not applicable in this context. The FreeStyle feature is described as collecting, storing, processing frames "to perform 2 dimensional motion analysis to determine frame to frame translation and rotation vectors, to form the composite extended image," which implies a more classical image processing approach rather than machine learning requiring a training set.

9. How the Ground Truth for the Training Set was Established

As a training set is not applicable (see point 8), this question is not relevant to the provided text.

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