The Leksell® Image Guidance Surgical System (LIGS) is intended for use in neurosurgical procedures to provide image guidance based on preoperative images which are visualized interactively with the aid of surgical tools.
Device Story
LIGS is a modular neurosurgical navigation system providing image-guided visualization during surgery. Inputs include preoperative CT and MR images. The system uses an infrared-based Measurement System with LED-equipped locators on patients and surgical tools to track spatial position and orientation in real-time. The system correlates patient anatomy with pre-planned surgical paths displayed on a workstation. Configurations include SurgiScope (motorized ceiling-mounted tool support), ViewScope (floorstand microscope), and FreeHand (manual tool tracking). Operated by surgeons in the OR, the system provides visual feedback of instrument location relative to patient anatomy, assisting in surgical planning and intra-operative guidance. Benefits include enhanced spatial awareness and precision during neurosurgical interventions.
Clinical Evidence
Bench testing only. Validation and verification studies were conducted to evaluate performance characteristics, demonstrating the system is capable of safely and accurately performing the stated intended use.
Technological Characteristics
Modular system comprising ScopePlan imaging workstation (HP C110, Unix-based), infrared measurement system (LED-based tracking), and various tool support configurations (motorized ceiling mount or manual floorstand). Connectivity includes workstation-based image retrieval and display. Software provides menu-driven GUI for image manipulation, registration, and real-time tracking of instrument position/orientation.
Indications for Use
Indicated for cranial and spinal neurosurgical procedures requiring image guidance based on preoperative images.
Regulatory Classification
Identification
A stereotaxic instrument is a device consisting of a rigid frame with a calibrated guide mechanism for precisely positioning probes or other devices within a patient's brain, spinal cord, or other part of the nervous system.
Predicate Devices
Elekta Leksell® Image Guidance System (LIGS) (K961639)
ISG Family of Viewing Wands® (cranial applications) (K960714)
ISG Family of Viewing Wands® (spinal applications) (K970865)
Submission Summary (Full Text)
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Original 510(k) Premarket Notification Leksell® Image Guidance Surgical System
K973684
MAR 31 1998
### 510(K) SUMMARY SECTION 21
This 510(k) Summary is being submitted in accordance with the requirements of SMDA 1990 and CFR 807.92.
### SUBMITTER INFORMATION SECTION 21.1
| a. | Company Name: | Elekta Instruments AB |
|----|--------------------------------------|--------------------------------------------------------------------------------------------|
| b. | Company Address: | Birger Jarlsgatan 53<br>Stockholm, Sweden S-103 93 |
| c. | Company Phone:<br>Company Facsimile: | (011) 46 8402 5400<br>(011) 46 8402 5500 |
| d. | Contact Person: | Sverker Glans<br>Vice President<br>Quality and Regulatory Affairs<br>Elekta Instruments AB |
### DEVICE IDENTIFICATION SECTION 21.2
| a. | Trade/Proprietary Name: | Leksell® Image Guidance Surgical System<br>(LIGS) |
|----|-------------------------|------------------------------------------------------|
| b. | Common Name | Neurological Image Guided Surgical System |
| c. | Classification Name: | Stereotaxic Instrument<br>Computed Tomography System |
| d. | Device Class: | Class II (per 21 CFR 882.4560, 21CFR<br>892.1750) |
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### IDENTIFICATION OF PREDICATE DEVICES SECTION 21.3
Table 21.1 provides relevant information on the predicate devices for the LIGS System.
| DEVICE NAME | COMPANY | 510(K)<br>NUMBER | 510(K)<br>CLEARANCE DATE |
|-----------------------------------------------------------|------------------------------|------------------|--------------------------|
| Elekta Leksell®<br>Image Guidance<br>System (LIGS) | Elekta Instruments<br>AB | K961639 | 26-July-96 |
| ISG Family of<br>Viewing Wands®<br>(cranial applications) | I.S.G.<br>Technologies, Inc. | K960714 | 29-May-96 |
| ISG Family of<br>Viewing Wands®<br>(spinal applications) | I.S.G.<br>Technologies, Inc. | K970865 | 4-June-97 |
#### SECTION 21.4 DEVICE DESCRIPTION
The Leksell® Image Guidance Surgical System (hereafter the LIGS System) which is the subject of this 510(k) Premarket Notification is a device System intended for use in neurosurgical procedures to provide image guidance based upon preoperative images which are visualized interactively with the aid of surgical tools. The LIGS System imports Computer Tomography (CT) and Magnetic Resonance (MR) images and provides a visual display of the images for pre-planning surgical paths. The images and pre-planned surgical paths can be viewed at a computer workstation in the operating room. The LIGS System is integrated with a Measurement System, which allows the patient in the operating room environment to be correlated with the diagnostic images
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obtained pre-operatively. The LIGS System may then be used for visual or instrumentation guidance during the surgical procedure.
The LIGS System is a modular System comprised of a set of components which may be used in conjunction with three basic Models of system configuration interfaced with a Measurement (position tracking) System:
- 1. The SurgiScope® Model is configured around a motorized ceiling mounted Integrated Tool Support System with integrated tool support software.
- 2. The ViewScope® Model is configured for use with a manual Floorstand Microscope System.
- 3. The FreeHand Model allows for the tracking of surgical tools without the use of a microscope.
The LIGS System consists of 6 major components that may be combined in different permutations in the SurgiScope®, ViewScope®, and proposed FreeHand Models. The six primary components of the LIGS System may be combined in various configurations, depending upon the features desired by the customer. Table 21.2 summarizes the configuration options of the three models of the LIGS System.
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# Table 21.2
| Component of LIGS | LIGS Model | | |
|--------------------------------------------------------|------------|-------------|----------|
| | ViewScope® | SurgiScope® | FreeHand |
| ScopePlan® Imaging System with<br>Computer Workstation | R | R | R |
| Intra-Operative Software | R | R | R |
| Measurement System | R | R | R |
| Integrated Tool Support System | N/A | R | N/A |
| Floorstand Microscope System | R | N/A | N/A |
| FreeHand Tool Tracking System | O | O | R |
| R=Required<br>O=Optional<br>N/A=Not Available | | | |
# Model Configurations of LIGS System
Sections 20.4.1-20.4.6 provide an overview of each component of the LIGS System.
# SECTION 21.4.1 SCOPEPLAN® IMAGING SYSTEM WITH COMPUTER WORKSTATION ·
Referring to Table 21.2, the Leksell® ScopePlan® Imaging System is a software based technology which provides surgical planning based upon Computer Tomography (CT), Magnetic Resonance Imaging (MRI), or other currently used 2D and 3D imaging techniques. ScopePlan® also provides for the retrieval of surgical planning studies and imaging during the surgical procedure, image correlation with a defined point (such as the microscope focus, probe tip, or instrument position and orientation), and image retrieval subsequent to the surgical procedure. ScopePlan® is to be used with specified commercially available surgical microscopes and accessories.
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ScopePlan® is supplied with a Hewlett-Packard C110 (or equivalent) computer running a Unix operating system. The Workstation includes a hard disk, a graphics board, and a high-resolution color monitor. A second computer Workstation may be installed in a separate location for pre-surgical review of patient images, and planning of the surgical intervention.
## SECTION 21.4.2 INTRA-OPERATIVE SOFTWARE
All Models of LIGS allow the surgeon to proceed through the surgical intervention by analyzing images derived from the ScopePlan®, planning the surgical intervention, and then monitoring the intervention at a computer workstation in the Operating Room. The Intra-Operative Software allows the surgeon to display, manipulate, and process images from the ScopePlan®, and interact with the data electronically to derive corroborative information related to the specific anatomy of the patient. The software display is a menu-driven Graphical User Interface, which allows the surgeon to recall to the screen images and surgical trajectories created with ScopePlan®. Image tracking features of the software allow the surgeon to conduct measurement/calibration check of the FreeHand instruments, conduct registration of the patient anatomy to the ScopePlan® image datasets, and display the position and orientation of the FreeHand Instrument on the ScopePlan® images during the conduct of the surgical intervention.
## SECTION 21.4.3 MEASUREMENT SYSTEM
The Measurement System is an infrared detection system, which is comprised of locators attached to the patient and tools, infrared detectors, a registration probe, and a processing unit. The locators and the probe contain infrared Light Emitting Diodes (LED's). The system accurately locates and continually tracks the patient, and simultaneously tracks the location of the tool of interest (microscope or FreeHand tool).
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## SECTION 21.4.4 INTEGRATED TOOL SUPPORT SYSTEM
The Integrated Tool Support System (ITS) is a motorized, manually operated, computermonitored system that is mounted on the ceiling of the operating room. The ITS supports surgical tools, primarily a surgical microscope, during surgical procedure. The surgeon, or other medical professional, activates electromechanical components to position and adjust the microscope during surgery. The location of the microscope focus may be tracked and displayed on the ScopePlan® images. The ITS is the heart of the SurgiScope® Model of LIGS, and is only available with the SurgiScope® Model.
# SECTION 21.4.5 FLOORSTAND MICROSCOPE SYSTEM
The Floorstand Microscope System is a manual floorstand with mounted microscope. The location of the microscope focus may be tracked and displayed on the ScopePlan® images. The ViewScope® Model of the LIGS System is provided with the floorstand microscope.
## SECTION 21.4.6 FREEHAND TOOL TRACKING SYSTEM
The FreeHand Tool Tracking System consists of commercially available hand-held instruments, guides, and probes for cranial and spinal applications which are tracked by the Measurement System via locating devices (LED's) embedded in either the instrument handle, or a specially designed "tracker" attached to the instrument. This allows for the use of the existing Measurement System to localize the tip position and spatial orientation of the hand-held instruments. An interface with the ScopePlan® provides for visual feedback to the surgeon by displaying the instrument location as an image on the ScopePlan.
The FreeHand Tool Tracking System is designed as a component of the LIGS System for use with either the ViewScope® Mode or the SurgiScope® Model. Additionally, customers may desire the FreeHand surgical options without the use of a microscope. In
### Confidential
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this event, the Freehand Tool Tracking System can be delivered as a separate Model of the LIGS System, without any microscope.
The modified LIGS System described in this Premarket Notification includes all of the safety features of the predicate device, as well as a number of additional safety features affiliated with the FreeHand Tool Tracking System.
#### INTENDED USE SECTION 21.5
The Leksell® Image Guidance Surgical System (LIGS) is intended for use in neurosurgical procedures to provide image guidance based on preoperative images which are visualized interactively with the aid of surgical tools.
#### TECHNOLOGICAL CHARACTERISTICS SECTION 21.6
The fundamental technical characteristics are similar to those of the predicate devices and are listed on the comparison chart provided in this 510(k) submission. Differences that exist between these systems relate to physical appearance and materials that do not affect the relative safety or effectiveness of the device.
#### SECTION 21.7 PERFORMANCE DATA
Validation and verification studies were conducted to evaluate the performance characteristics of the Leksell® Image Guidance Surgical System. The results of these studies demonstrated that the Leksell® Image Guidance Surgical System is capable of safely and accurately performing the stated intended use.
#### 510(K) CHECKLIST SECTION 21.8
The Premarket Notification for the Leksell® Image Guidance Surgical System contains all the information required by 21 CFR 807.87. A completed copy of the Premarket Notification 510(k) Reviewer's Checklist is provided in the submission.
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### CONCLUSIONS DRAWN FROM STUDIES SECTION 20.9
The results of performance testing demonstrate that the Leksell® Image Guidance Surgical System is capable of safely and accurately performing the stated intended use.
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Image /page/8/Picture/1 description: The image shows the seal of the Department of Health & Human Services - USA. The seal is circular and contains an emblem of an eagle with three lines representing its body. The text "DEPARTMENT OF HEALTH & HUMAN SERVICES - USA" is arranged around the emblem.
Food and Drug Administration 9200 Corporate Boulevard Rockville MD 20850
MAR 3 1 1998
Ms. Carol L. Patterson · Official Correspondent for Elekta AB c/o Patterson Consulting Group 18140 Smokesignal Drive San Diego, California 92630
Re: K973684 Elekta Leksell® Image Guidance Trade Name: Surgical System Requlatory Class: II Product Code: HAW January 15, 1998 Dated: January 20, 1998 Received:
### Dear Ms. Patterson:
We have reviewed your Section 510(k) notification of intent to market the device referenced above and we have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to 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, Druq, and Cosmetic Act (Act). You may, therefore, market the device, subject to the general controls provisions of the Act. The general controls provisions of the Act include requirements for annual reqistration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration.
If your device is classified (see above) into either class II (Special Controls) or class III (Premarket Approval), it may be subject to such additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 895. A substantially equivalent determination assumes compliance with .... _ the current Good Manufacturing Practice requirement, as set forth in the Quality System Requlation (QS) for Medical Devices: General regulation (21 CFR Part 820) and that, through periodic (QS) inspections, the Food and Drug Administration (FDA) will verify such assumptions. Failure to comply with the GMP requlation may result in regulatory action. In addition, FDA may publish further announcements concerning your device in the Federal Register. Please note: this response to your premarket notification submission does not affect any obligation you might have under sections 531 through 542 of the Act for devices under the Electronic Product Radiation Control provisions, or other Federal laws or regulations.
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### Page 2 - Ms. Patterson
This letter will allow you to begin marketing your device as described in your 510 (k) premarket notification. The FDA finding of substantial equivalence of your device to a legally marketed predicate device results in a classification for your device and thus, permits your device to proceed to the market.
If you desire specific advice for your device on our labeling regulation (21 CFR Part 801 and additionally 809.10 for in vitro diagnostic devices), please contact the Office of Compliance at (301) 594-4595. Additionally, for questions on the promotion and advertising of your device, please contact the Office of Compliance at (301) 594-4639. Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR 807.97). Other general information on your responsibilities under the Act may be obtained from the Division of Small Manufacturers Assistance at its toll-free number (800) 638-2041 or (301) 443-6597 or at its internet address "http://www.fda.gov/cdrh/dsmamain.html".
Sincerely yours,
Celia M. Witten, Ph.D., M.D. / Director Division of General and Restorative Devices Office of Device Evaluation Center for Devices and Radiological Health
Enclosure
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Elekta Instruments AB Response to 510(k) #K973684 Deficiencies January 15, 1998
K973684
# INDICATIONS FOR USE
510(k) Number: To Be Assigned By FDA
Device Name: Elekta Leksell® Image Guidance Surgical System
Indications For Use: The Leksell® Image Guidance Surgical System (LIGS) is intended for use in cranial and spinal neurosurgical procedures to provide image guidance based on preoperative images which are visualized interactively with the aid of surgical tools.
PLEASE DO NOT WRITE BELOW THIS LINE - CONTINUE ON ANOTHER PAGE IF NEEDED
Concurrence of CDRH, Office of Device Evaluation (ODE)
| (Division Sign-Off) | |
|-----------------------------------------|---------|
| Division of General Restorative Devices | |
| 510(k) Number | K973684 |
| Prescription Use | <div>✓</div> | OR | Over-The-Counter Use |
|------------------|--------------|----|----------------------|
|------------------|--------------|----|----------------------|
(Per 21 CFR 801.109)
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.