How to Use Pacs for Real-time Surgical Navigation and Planning

Introduction to PACS in Modern Surgery

Picture Archiving and Communication Systems (PACS) have become an indispensable tool in surgical departments worldwide. By digitizing medical imaging and enabling instant, secure access across the enterprise, PACS allows surgeons to plan and navigate procedures with unprecedented precision. The shift from film-based radiology to digital platforms has not only streamlined workflows but also opened the door to real-time image guidance during surgery. Today, PACS is a core component of the surgical informatics ecosystem, integrating with electronic health records (EHRs), 3D visualization software, and intraoperative navigation systems. This article explores how surgeons can leverage PACS for real-time navigation and planning, from preoperative segmentation to intraoperative guidance and postoperative assessment.

According to the Radiological Society of North America, PACS reduces the time to access imaging studies by over 80% compared to film-based methods, directly impacting surgical decision-making speed and accuracy. The ability to overlay preoperative scans onto live video feeds or stereotactic frames has transformed procedures in neurosurgery, orthopedics, and oncology. In this expanded guide, we detail the practical steps for using PACS in surgical navigation, the underlying technologies, benefits, challenges, and emerging trends that will shape the future of image-guided surgery.

Understanding PACS: Technology and Workflow

PACS is a combination of hardware and software that manages medical images in the Digital Imaging and Communications in Medicine (DICOM) format. It consists of four main components: image acquisition devices (CT, MRI, ultrasound, X-ray), a central archive for storage, a network infrastructure for transmission, and display workstations for viewing and manipulation. In a surgical context, PACS supports not just static viewing but also multiplanar reconstruction, volume rendering, and 3D modeling that are critical for navigation.

The workflow typical in a surgical PACS environment is as follows: imaging is performed preoperatively and transmitted to the PACS server via DICOM. Surgeons access the studies through a web-based viewer or dedicated workstation. For navigation, the PACS data is exported (often as DICOM series) to a navigation system, where it is registered to the patient's anatomy in the operating room. Some advanced PACS offer built-in navigation modules or APIs that allow direct integration with surgical robots and tracking systems.

Key technical standards that enable this integration include DICOM (for image format) and DICOM Worklist (for scheduling). Additionally, HL7 FHIR is increasingly used to link PACS with EHRs for seamless data exchange. Understanding these standards is essential for surgical teams implementing real-time navigation, as interoperability issues remain a major barrier.

Real-time surgical navigation relies on the continuous availability of updated imaging data that aligns with the patient's current anatomy. PACS provides the backbone by storing and delivering high-resolution images that can be reformatted on the fly. During surgery, the navigation system correlates the preoperative PACS images with the actual position of surgical instruments using optical or electromagnetic tracking. This process is known as image-to-patient registration.

There are two primary approaches to image-guided surgery: frame-based and frameless. Frame-based systems, common in stereotactic neurosurgery, use a rigid head frame that creates a fixed coordinate system referencing preoperative PACS scans. Frameless systems use surface markers or anatomical landmarks registered to the PACS images. In both cases, PACS serves as the authoritative image source, and the accuracy of navigation is directly tied to the quality and timeliness of the PACS data.

Integration with Augmented Reality and Robotics

Beyond basic navigation, PACS data can be fused with live video feeds to create augmented reality (AR) overlays. For example, a surgeon performing a spinal fusion can see a 3D reconstruction of the vertebrae from PACS projected onto the patient's back through a headset or monitor. Robotic surgical systems, such as those used in orthopedics (e.g., MAKO, ROSA), rely on PACS-derived 3D models to plan implant placement and guide the robot intraoperatively. The National Institutes of Health (NIH) has published several studies demonstrating that PACS-integrated robotic navigation reduces outlier screw placement in spine surgery from 20% to under 5% (see NIH study on robotic spine navigation).

Preoperative Planning: Detailed Steps Using PACS

Effective navigation begins long before the patient enters the operating room. Preoperative planning using PACS involves several critical steps that leverage advanced imaging features.

Step 1: Access and Select the Appropriate Imaging Series

The surgeon reviews the available PACS studies, typically including CT with contrast, MRI with multiple sequences, and sometimes PET/CT fusion. Using a PACS viewer, the surgeon selects the series that best demonstrates the pathology and surrounding anatomy. For navigation, thin-slice CT scans (≤1 mm) are preferred because they provide sufficient resolution for accurate segmentation and registration.

Step 2: Image Segmentation and 3D Reconstruction

Segmentation isolates specific structures—such as a tumor, blood vessels, or bony landmarks—from the surrounding tissue. Many modern PACS viewers include semi-automated segmentation tools based on thresholding, region growing, or machine learning. The segmented data can be exported as surface models (STL files) or volume renderings. For example, in liver surgery, the surgeon segments the hepatic vasculature and tumor to plan a resection with clear margins while preserving healthy tissue.

Step 3: Simulating the Surgical Approach

With the 3D model loaded into a planning workstation (often integrated with PACS), the surgeon can simulate different trajectories, incisions, and instrument placements. This is particularly useful in cranial surgery, where the optimal entry point and angle must avoid eloquent cortex and major vessels. Some PACS platforms now incorporate virtual reality viewing capabilities, allowing the surgeon to "walk through" the anatomy before stepping into the OR.

Once the plan is finalized, the relevant imaging series and segmentation masks are exported in DICOM or a proprietary format compatible with the navigation system. This transfer can be done via local network, USB, or cloud-based PACS solutions. It is essential to verify that the exported data maintains spatial coordinates and is correctly labeled to avoid mismatch during registration.

Intraoperative Use of PACS

During surgery, PACS plays a dual role: providing real-time access to preoperative images and, in some configurations, enabling intraoperative imaging updates.

Intraoperative Imaging Updates

In procedures where brain shift or tissue deformation occurs (e.g., during tumor resection), the original PACS scan may no longer be accurate. Advanced operating rooms are equipped with intraoperative CT or MRI scanners that acquire new images and send them directly to PACS. The updated images are then used for re-registration, allowing the navigation system to correct for anatomical changes. This iterative process dramatically improves the completeness of tumor resection in glioblastoma surgery.

Live Collaboration Through PACS

PACS supports multidisciplinary collaboration during surgery. A neurosurgeon can share the live navigation view with a remote radiologist or pathologist through a secure PACS link, obtaining real-time advice on tissue boundaries or biopsy targets. This telecollaboration is especially valuable in teaching hospitals and complex cases where expert consultation is needed.

Minimizing Radiation Exposure

One of the greatest advantages of PACS-integrated navigation is the reduction in intraoperative fluoroscopy. With accurate preoperative registration, surgeons can place screws or catheters without repeated X-rays. A study in the Journal of Neurosurgery: Spine found that using PACS-based navigation reduced intraoperative radiation exposure to the surgical team by up to 90% (JNS Spine study on radiation reduction).

Benefits of PACS for Surgical Outcomes

The integration of PACS into surgical navigation provides multifaceted benefits that extend beyond the operating room.

Improved accuracy: Sub-millimeter registration of PACS images to patient anatomy reduces errors in target localization, leading to higher success rates for biopsies, resections, and implant placements.
Shorter operative times: Faster access to images and pre-planned trajectories mean less time spent searching for landmarks or interpreting anatomy during surgery.
Better patient safety: Reduced radiation exposure and lower risk of iatrogenic injury due to precise guidance.
Enhanced educational value: PACS allows surgical trainees to review cases pre- and postoperatively, correlating imaging findings with intraoperative video, thereby accelerating the learning curve.
Cost savings: Shorter procedures and fewer complications translate to reduced hospital stays and lower overall healthcare costs.

Hospitals that have implemented PACS-integrated navigation report a 30–40% reduction in revision surgeries for spinal and cranial procedures, according to data from the FDA's Computer-Assisted Surgical Systems guidance.

Despite its clear advantages, deploying PACS for live surgical guidance presents several hurdles that must be addressed.

Technical Compatibility and Interoperability

Different PACS vendors and navigation systems often use proprietary protocols or formats. Even with the DICOM standard, the metadata required for registration (e.g., patient orientation, slice spacing) may be lost or misinterpreted. Institutions must invest in middleware or universal viewers that can harmonize data between systems. The Integrating the Healthcare Enterprise (IHE) initiative has introduced profiles specifically for surgical navigation workflows, but adoption is still incomplete.

Cost and Infrastructure

Upgrading to a PACS capable of real-time navigation requires significant investment in hardware (high-resolution displays, advanced workstations, network switches) and software licenses. Hospitals must also budget for maintenance and periodic upgrades to keep pace with evolving security standards and imaging technology.

Training and Workflow Integration

Surgeons, radiologists, and OR staff need training not only on the technical operation of PACS but also on new workflows. For instance, preoperative segmentation takes time; if not properly integrated into the surgical schedule, it can cause delays. Some institutions employ dedicated imaging specialists or "PACS navigators" to assist with case preparation.

Data Security and Patient Privacy

Real-time PACS access in a networked OR increases the attack surface for cyber threats. Hospitals must ensure that PACS servers are protected by robust firewalls, encryption, and access controls. Compliance with HIPAA (in the US) or GDPR (in Europe) is mandatory, especially when sharing navigation data with remote collaborators.

A survey by the American College of Radiology highlights that 60% of PACS administrators consider cybersecurity their top concern for the next five years (ACR data security resources).

Future Directions: AI, Cloud, and Beyond

The next generation of PACS will be faster, smarter, and more deeply integrated into surgical workflows.

Artificial Intelligence and Automated Segmentation

AI algorithms are already being deployed within PACS to automatically segment organs, detect lesions, and even suggest surgical margins. This reduces the manual effort of preoperative planning and can provide real-time feedback during surgery. For example, an AI model can highlight the optic nerve in a sinus surgery CT, alerting the surgeon to keep the instrument away.

Cloud-Based PACS and 5G Connectivity

Cloud PACS allows surgeons to access imaging studies and navigation plans from any location, using any device. With the rollout of 5G networks, the latency for transferring large datasets (e.g., 3D volumetrics) will drop below 10 milliseconds, making true real-time remote guidance feasible. This could enable expert surgeons to assist in cases at remote or understaffed hospitals without traveling.

Digital Twins and Personalized Models

Combining PACS images with genomics, lab values, and biomechanical data, researchers are building "digital twins" of patients—dynamic virtual models that mimic the living anatomy. In the OR, the surgeon can interact with the digital twin through PACS, testing different maneuvers in simulation before performing them on the patient. This concept is still nascent but holds tremendous promise for complex reconstructive and oncologic surgeries.

Interoperability Standards Evolution

New standards like DICOMweb and FHIR are enabling easier integration of PACS with other surgical systems. In the future, a surgeon may be able to push a button on the navigation system to request a new intraoperative scan and have it appear automatically in PACS within seconds, with all metadata correctly aligned.

Conclusion

PACS has evolved from a simple image archive into a dynamic platform for real-time surgical navigation and planning. By providing instant access to high-quality imaging, segmentation tools, and integration with navigation systems, PACS empowers surgeons to perform procedures with unparalleled precision and safety. While challenges of cost, compatibility, and training remain, the continuous advancement of AI, cloud computing, and interoperability standards promises to make these systems even more powerful and accessible. Surgical teams that invest in mastering PACS-based navigation today will be well-positioned to deliver better outcomes for their patients tomorrow.

Whether you are a surgeon, radiologist, or hospital administrator, understanding how to optimize PACS for surgical navigation is a critical step toward achieving the triple aim of healthcare: improved patient experience, better population health, and reduced per capita costs.