The Imbio PHA Software device is designed to measure the maximal diameters of the right and left ventricles of the heart, the main pulmonary artery, and the ascending aorta from a volumetric CTPA acquisition and report the RV/LV and Pa/Ao ratios. PHA analyzes cases using an artificial intelligence algorithm to identify the location and measurements of the anatomy. The PHA software provides the user with annotated images showing measurements. Its results are not intended to be used on a stand-alone basis for clinical decision-making or otherwise preclude clinical assessment of CTPA cases.
Device Story
Imbio PHA is a SaMD post-processing tool for CT pulmonary angiography (CTPA) datasets. It uses deep learning algorithms to automatically segment the right/left ventricles, main pulmonary artery, and ascending aorta; calculates maximal diameters; and computes RV/LV and PA/Ao ratios. The software operates as a command-line executable, typically integrated into radiological workflows at PACS workstations. It outputs annotated DICOM images and a summary PDF report. Physicians use these outputs as an aid to clinical assessment; results are not for stand-alone decision-making. The device benefits patients by providing automated, standardized measurements to support the evaluation of pulmonary embolism or hypertension.
Clinical Evidence
No clinical testing was conducted. Bench testing utilized 100 contrast-enhanced CTPA datasets from multiple centers and vendors (GE, etc.) with varying slice thicknesses (0.75mm–2.00mm). Performance was validated against ground truth established by three U.S. board-certified radiologists (min. 10 years experience). The primary endpoint was the Intra-class correlation coefficient (ICC) between the algorithm and radiologists. Results showed an ICC of 0.94, meeting the acceptance criterion of >0.90.
Technological Characteristics
SaMD; deep learning-based segmentation and measurement; inputs: non-gated CTPA DICOM datasets; outputs: annotated DICOM images and PDF reports; command-line interface; standalone software; no direct hardware interface; DICOM compliant.
Indications for Use
Indicated for patients undergoing CT pulmonary angiography (CTPA) scans, primarily for suspicion of pulmonary embolism or pulmonary hypertension, to assist physicians in measuring maximal diameters of the right and left ventricles, main pulmonary artery, and ascending aorta.
Regulatory Classification
Identification
A medical image management and processing system is a device that provides one or more capabilities relating to the review and digital processing of medical images for the purposes of interpretation by a trained practitioner of disease detection, diagnosis, or patient management. The software components may provide advanced or complex image processing functions for image manipulation, enhancement, or quantification that are intended for use in the interpretation and analysis of medical images. Advanced image manipulation functions may include image segmentation, multimodality image registration, or 3D visualization. Complex quantitative functions may include semi-automated measurements or time-series measurements.
Special Controls
*Classification.* Class II (special controls; voluntary standards—Digital Imaging and Communications in Medicine (DICOM) Std., Joint Photographic Experts Group (JPEG) Std., Society of Motion Picture and Television Engineers (SMPTE) Test Pattern).
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Imbio, Inc Lauren Keith Director of Engineering 1015 Glenwood Ave Floor 4 Minneapolis, Minnesota 55405
Re: K241847
August 30, 2024
Trade/Device Name: Imbio PHA (4.0.0) Regulation Number: 21 CFR 892.2050 Regulation Name: Medical Image Management And Processing System Regulatory Class: Class II Product Code: QIH Dated: August 6, 2024 Received: August 6, 2024
Dear Lauren Keith:
We have reviewed your section 510(k) premarket notification of intent to market the device referenced above and have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food, Drug, and Cosmetic Act (the Act) that do not require approval of a premarket approval application (PMA). You may, therefore, market the device, subject to the general controls provisions of the Act. Although this letter refers to your product as a device, please be aware that some cleared products may instead be combination products. The 510(k) Premarket Notification Database available at https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm identifies combination product submissions. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration. Please note: CDRH does not evaluate information related to contract liability warranties. We remind you, however, that device labeling must be truthful and not misleading.
If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 898. In addition, FDA may publish further announcements concerning your device in the Federal Register.
Additional information about changes that may require a new premarket notification are provided in the FDA guidance documents entitled "Deciding When to Submit a 510(k) for a Change to an Existing Device" (https://www.fda.gov/media/99812/download) and "Deciding When to Submit a 510(k) for a Software Change to an Existing Device" (https://www.fda.gov/media/99785/download).
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Your device is also subject to, among other requirements, the Quality System (QS) regulation (21 CFR Part 820), which includes, but is not limited to, 21 CFR 820.30, Design controls; 21 CFR 820.90, Nonconforming product; and 21 CFR 820.100, Corrective and preventive action. Please note that regardless of whether a change requires premarket review. the OS regulation requires device manufacturers to review and approve changes to device design and production (21 CFR 820.30 and 21 CFR 820.70) and document changes and approvals in the device master record (21 CFR 820.181).
Please be advised that FDA's issuance of a substantial equivalence determination does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal statutes and regulations administered by other Federal agencies. You must comply with all the Act's requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Part 801); medical device reporting of medical device-related adverse events) (21 CFR Part 803) for devices or postmarketing safety reporting (21 CFR Part 4, Subpart B) for combination products (see https://www.fda.gov/combination-products/guidance-regulatory-information/postmarketing-safety-reportingcombination-products); good manufacturing practice requirements as set forth in the quality systems (QS) regulation (21 CFR Part 820) for devices or current good manufacturing practices (21 CFR Part 4, Subpart A) for combination products; and, if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR Parts 1000-1050.
Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR 807.97). For questions regarding the reporting of adverse events under the MDR regulation (21 CFR Part 803), please go to https://www.fda.gov/medical-device-safety/medical-device-reportingmdr-how-report-medical-device-problems.
For comprehensive regulatory information about mediation-emitting products, including information about labeling regulations, please see Device Advice (https://www.fda.gov/medicaldevices/device-advice-comprehensive-regulatory-assistance) and CDRH Learn (https://www.fda.gov/training-and-continuing-education/cdrh-learn). Additionally, you may contact the Division of Industry and Consumer Education (DICE) to ask a question about a specific regulatory topic. See the DICE website (https://www.fda.gov/medical-device-advice-comprehensive-regulatoryassistance/contact-us-division-industry-and-consumer-education-dice) for more information or contact DICE by email (DICE@fda.hhs.gov) or phone (1-800-638-2041 or 301-796-7100).
Sincerely,
Jessica Lamb
Jessica Lamb, Ph.D. Assistant Director Imaging Software Team DHT 8B: Division of Radiological Imaging Devices and Electronic Products OHT 8: Office of Radiological Health Office of Product Evaluation and Quality Center for Devices and Radiological Health
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### Indications for Use
Submission Number (if known)
#### K241847
Device Name
Imbio PHA (4.0.0)
#### Indications for Use (Describe)
The Imbio PHA Software device is designed to measure the maximal diameters of the right and left ventricles of the heart, the main pulmonary artery, and the ascending aorta from a volumetric CTPA acquisition and report the RV/LV and Pa/Ao ratios. PHA analyzes cases using an artificial intelligence algorithm to identify the location and measurements of the PHA software provides the user with annotated images showing measurements. Its results are not intended to be used on a stand-alone basis for clinical decision-making or otherwise preclude clinical assessment of CTPA cases.
Type of Use (Select one or both, as applicable)
> Prescription Use (Part 21 CFR 801 Subpart D)
Over-The-Counter Use (21 CFR 801 Subpart C)
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| 510(k) #: | K241847 | 510(k) Summary | Prepared on: 2024-08-27 |
|------------------------------------|--------------------------------------------------------------|----------------|-------------------------|
| Contact Details | 21 CFR 807.92(a)(1) | | |
| Applicant Name | Imbio, Inc | | |
| Applicant Address | 1015 Glenwood Ave Floor 4 Minneapolis MN 55405 United States | | |
| Applicant Contact Telephone | 608-213-7100 | | |
| Applicant Contact | Dr. Lauren Keith | | |
| Applicant Contact Email | laurenkeith@imbio.com | | |
| Device Name | 21 CFR 807.92(a)(2) | | |
| Device Trade Name | Imbio PHA (4.0.0) | | |
| Common Name | Medical image management and processing system | | |
| Classification Name | Automated Radiological Image Processing Software | | |
| Regulation Number | 892.2050 | | |
| Product Code(s) | QIH | | |
| Legally Marketed Predicate Devices | 21 CFR 807.92(a)(3) | | |
| Predicate # | Predicate Trade Name (Primary Predicate is listed first) | Product Code | |
| K203256 | Imbio RV/LV | QIH | |
| Device Description Summary | 21 CFR 807.92(a)(4) | | |
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lmbio's PHA Software is a set of medical image post-processing computer algorithms that together perform automated right and left ventricle, pulmonary artery (PA), and aorta (Ao) measurements from CT pulmonary angiography (CTPA) scans, and reports the RV/LV and PA/Ao ratios. The Imbio PHA is a single command-line executable program that may be run directly from the or through scripting and thus the user interface is minimal.
lmbio PHA Software is a Software as a Medical Device (SaMD) intended to provide annotated images and a PDF report that will be read most typically at a PACS workstation. Imbio PHA Software is an aid, only used to support a physician in the analysis of CTPA images.
The Imbio PHA Software program reads in CTPA DICOM datasets, processes the data, then writes output DICOM files and summary reports to a specified directory. Imbio PHA Software outputs DICOM CT images overlaid with color-codings indicating where the measurements were made. Additionally, a summary PDF report is output.
lmbio PHA Software does not interface directly with any CT scanner or data collection equipment; instead the software imports data previously generated by such equipment and is integrated as part of the radiological workflow, reducing the risk of use errors.
100 contrast-enhanced CT pulmonary angiography (CTPA) datasets were used for standalone performance assessment. The datasets were sourced from multiple centers and multiple databases and included a range of convolution kernels (vendor equivalent of GE's Soft, Detail, Standard, and Standard Iterative kernels) and sice thicknesses (0.75 mm, 1.5 mm, and 2.00 mm) from the four major CT scanner vendors. The datasets are representative of the intended patients because they are all cinically indicated for a CTPA scan, which is primarily indicated for suspicion of pulmonary embolism or pulmonary hypertension.
Three expert, U.S. board-certified radiologists practicing within the United States were enrolled to perform ground truthing of the performance datasets. Each truther had a minimum of 10 years clinical experience. The ground truthing exercise consisted of each radiologist measuring the diameter of the pulmonay artery trunk at the bifurcation and the aorta diameter at the same slice. Intra-class correlation coefficients were calculated to show equivalency. There were two acceptance criterion:
*ICC of all measurements (annotators and algorithm) > 0.90 (excellent)
*ICC of all measurements (annotators and algorithm) within 95% Cl of the ICC of only annotators
# Intended Use/Indications for Use
### 21 CFR 807.92(a)(5)
The Imbio PHA Software device is designed to maximal diameters of the right and left ventricles of the heart, the main pulmonary artery, and the ascending aorta from a volumetric CTPA acquisition and report the RV/LV and Pa/Ao ratios. PHA analyzes cases using an artificial intelligence algorithm to identify the location and measurements of the anatomy. The PHA software provides the user with annotated images showing measurements. Its results are not intended to be used on a stand-alone basis for clinical decisionmaking or otherwise preclude clinical assessment of CTPA cases.
# Indications for Use Comparison
The Indications for Use differ slightly between the proposed devices. The FUs have been reworded slightly to include the main pulmonary artery and ascending aorta measurements. The overall intended use of the devices are equivalent: to use deeplearning models to measure diameters of clinically relevant cardiovascular strom a CTPA image. The differences in IFU statements have no neqative impact on safectiveness because neither the predicate's nor the subject device's results are not intended to be used on a stand-alone basis for clinical decision-making or otherwise preclude clinical assessment of CTPA cases.
### Technological Comparison
21 CFR 807.92(a)(6)
## 21 CFR 807.92(a)(5)
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Proposed Device Characteristics Name: Imbio PHA 510(k) Number: TBD Product Code: OlH Requlation Name: Picture Archiving and communications systems Regulation Number: 21 CFR 892.2050 lnput Data Requirements - General: Non-qated, CT Pulmonary Angiography images DICOM compliant: Yes LV Segmentation: Yes - Deep Learning RV Segmentation: Yes - Deep Learning mPA Segmentation: Yes - Deep Learning Ao Segmentation: Yes - Deep Learning Diameters Measurements: Yes - Automated Fully-automated: Yes Interface: Command-line Ability to QA Results: Yes - via outputs Outputs: Report, DICOM Secondary Capture series
Proposed Indications for Use: The Imbio PHA Software device is designed to measure the maximal diameters of the right and left ventricles of the heart, the main pulmonary and the ascending aorta from a volumetric CTPA acquisition and report the RV/LV and Pa/Ao ratios. PHA analyzes cases using an artificial intelligence algorithm to identify the location and measurements of the anatomy. The PHA software provides the user with annotated images showing measurements. Its results are not intended to be used on a stand-alone basis for clinical decision-making or otherwise preclude clinical assessment of CTPA cases.
Predicate Device Characteristics Name: Imbio RV/LV 510(k) Number: K203256 Product Code: QIH Regulation Name: Picture Archiving and communications systems Requlation Number: 21 CFR 892.2050 Input Data Requirements - General: Non-qated, CT Pulmonary Angiography images DICOM compliant: Yes LV Segmentation: Yes - Deep Learning RV Segmentation: Yes - Deep Learning mPA Segmentation: No Ao Segmentation: No Diameters Measurements: Yes - Automated Fully-automated: Yes Interface: Command-line Ability to QA Results: Yes - via outputs Outputs: Report, DICOM Secondary Capture series
Predicate Indications for Use: The Imbio RV/LV Software device is designed to maximal diameters of the right and left ventricles of the heart from a volumetric CTPA acquisition and report the ratio of those measurements. RV/LV analyzes cases using an artificial intelligence algorithm to identify the location and measurements of the RV/LV software provides the user with annotated images showing ventricular measurements. Its results are not intended to be used on a stand-alone basis for clinical decisionmaking or otherwise preclude clinical assessment of CTPA cases.
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## Non-Clinical and/or Clinical Tests Summary & Conclusions 21 CFR 807.92(b)
No clinical testing was conducted. The Imbio PHA Software provides quantitative metrics with well-known clinical value. Non-Clinical testing was conducted to ensure that the measurements provided by the PHA Software, specifically the PA and Ao diameters, resemble measurements of the same anatomy performed by radiologists. The ICC between three expert radiologists and the algorithm results is 0.94, indicating excellent agreement.
The conclusions drawn from the nonclinical tests demonstrate that the device is as safe, as effective as Imbio RV/LV (K203256).
Two short videos show you everything — or skip straight to the written tutorial if you'd rather read. You can reopen this any time from the Tutorial button in the top bar.
Part 1 — Search, results, and everyday workflows 16 min
Part 2 — Embeddings: the galaxy map 3 min
1. Search: exact and fuzzy
Type a phrase like "coronary artery calcification" into the search box. You get two kinds of results. Exact results match the literal phrase — prefix searches work ("coronary artery calcificati") but suffix searches do not. Fuzzy results match on the meaning and intent of your phrase rather than the exact words, and are sorted by relevance score. Hover over the Exact or Fuzzy badge on any row to see exactly why it matched.
Use the checkboxes above the results to narrow: SaMD keeps only software-only devices, AI / ML keeps only devices with AI.
Exact vs. fuzzy search: what's the difference?
Exact matches on the literal phrase (prefix search works, suffix does not). Fuzzy matches on the meaning and intent of the phrase rather than the exact words. Hover over the badge on any row to see why it matched.
You search "coronary artery calcification" and want only software devices with AI. What two filters do you apply?
Narrow by SaMD (software-only devices), then narrow by AI/ML (devices with AI).
2. The results table
Scroll right in the results table. The intended use is extracted for you — no need to open the PDF. The device story gives a high-level snapshot of what the device does and how it's used. The AI Performance sub-table shows each output name, acceptance criteria, observed values, and development/test dataset descriptions — the same format Innolitics uses for regulatory strategy outputs, and the fastest high-level fingerprint of an AI device. It is AI-generated but has been very reliable in practice.
Where do you find a device's intended use without opening the PDF?
Scroll right in the search results table. The intended use column is extracted for you; no need to dig into the 510(k) summary PDF.
What does the AI Performance sub-table show, and why is it useful?
Output name, acceptance criteria, observed values, development dataset description, and test dataset description. It's the same format we use for regulatory strategy output and Fast 510(k) input, and the fastest high-level fingerprint of an AI device. AI-generated but reliable in practice.
3. Judging fuzzy relevance
Fuzzy results trail off in relevance as you scroll. Use three signals to decide how far down to go: the fuzzy badge explanations, the intended use column, and whether your target output (e.g., Cobb angle) still appears in the AI Performance sub-table. Once it stops appearing, you're past the relevant zone. A top hit with a low score (~0.4) and a stretched explanation is a hint the closest predicates are far away — the project may be headed for De Novo. Note the fuzzy search is a pattern match: it doesn't handle negation ("not") well, and hardware devices can appear — filter by SaMD/AI ML to cut them.
How do you judge how far down fuzzy search results to go?
Use the relevancy signals: the fuzzy badge explanations, the intended use column, and whether the target output (e.g., Cobb angle) still appears in the AI Performance sub-table. Once it stops appearing, results are trailing off in relevancy.
4. Device detail page: chat and citations
Click a device name to open its detail page: device facts on the left, a chat window on the right. Ask something like "Describe the training data". The answer carries little citation bubbles — click one to jump to the highlighted passage in the source PDF, so you can verify every AI answer against the document. There's also a Download PDF button for sharing.
How do you verify an AI chat answer on the device detail page?
Click the citation bubbles to jump to the relevant highlight in the source document.
Reading rule for every project: how many summaries do you read in full?
At least the three most relevant 510(k) or De Novo summaries, in full. After that, use targeted chat questions to confirm your memory quickly. The tool supports this professional habit — it doesn't replace it.
5. Side-by-side comparison
Select multiple rows in the results table (aim for under ~10), then open the PDF Viewer tab. Ask one question — it goes to all selected devices in parallel, each with citations. This is the fastest way to compare and contrast devices: training data, PCCP scope, how they handled adding new scanners, and so on.
What does the side-by-side PDF viewer mode do?
Select multiple devices, open the PDF viewer tab, and ask one question (e.g., "Describe the training data"). It queries all selected devices simultaneously with citations, so you can compare and contrast quickly.
6. Collections
With rows selected, go to the Collections tab and create a labeled collection (e.g., "Cobb Angle Project"). Reload that selection any time — before a client call, pull up the collection and ask questions across all of its devices at once.
How do you save a set of selected devices for later use?
Select the rows, go to the Collections tab, and create a labeled collection (e.g., "Cobb Angle Project"). You can reload the selection anytime and carry it into the PDF viewer and other tabs that support selections.
7. Product codes and the regulations tree
Click a product code in the results to jump to it in the regulations tree — identification text, sibling product codes, and devices you can open in a PDF viewer on the right. Click a regulation number to see its identification, special controls, and related product codes. You can also search by product code or regulation number at the top of the tree. Always read the special controls if any exist for your device — it broadens your search and sharpens pre-kickoff research.
What can you do from the regulations tree view?
Browse product codes and regulation numbers, read the identification text and special controls, browse sibling product codes, open device PDFs on the right, and search by product code or regulation number at the top of the tree.
8. Chart view
Click Show Chart and segment by regulation number (or product code) to see which regulations dominate your result set. Clicking a regulation takes you into the regulations tree. Great for spotting that most matches are, say, hardware laparoscopic devices — a cue to go back and filter.
How do you see which regulations dominate a search result set?
Click "Show Chart" and segment by Regulation Number. Clicking a regulation takes you to the regulations tree.
9. The predicate graph
Open the Predicates tab for a family-tree view of predicate relationships. Click a node to trace its parents and children; selections from search carry over pre-selected. Commonly predicated devices are worth reading — a lot of people predicated them for a reason. The visual lineage is also handy on client calls, e.g. to show how a predicate family evolved and justify why your predicate still holds.
In the predicate graph, why are commonly predicated devices worth reading?
A lot of people predicated them for a reason. Clicking a node traces parents and children, and selections from search carry over pre-selected.
10. Embeddings: the galaxy map
The Embeddings tab plots every matching document in a 2-D "galaxy map" where semantically similar devices cluster together. Hover or click clusters to explore, and let AI label the clusters for you. Embeddings beat product codes for grouping: two devices can carry different product codes (LLZ vs. QIH) yet do the same thing — the embedding captures the meaning of the intended use and device story. This is also exactly how retrieval-augmented generation (RAG) works under the hood, and it makes a great visual on client calls.
Try it yourself
Head to the search page and work through a few of these AI/ML fuzzy searches to build intuition: perivascular fat on CT · aortic valve calcification opportunistic screening on noncontrast CT · breast cancer prediction on digital pathology slides · autism detection · gestational age prediction · a hearing aid that can also detect a pulse · foundation model based analysis of ECG · large language models · penetration test. Watch how the relevance scores, intended use, and AI Performance tables tell you when results stop being meaningful.