Electromagnetic Navigation System Research Articles

A Simulation Framework for Magnetic Continuum Robots

Remote magnetic navigation is a technology used to robotically steer magnetic medical instruments, such as magnetic catheters and guidewires, for minimally invasive surgery. The ability to model and simulate the behavior of these magnetic instruments in complex anatomies is important for their clinical use in many ways. Simulation frameworks can improve their design, characterization, and automatic control capabilities, as well as provide training simulators for physicians. In this work we introduce a new simulation framework that accounts for both magnetic actuation and interactions forces with meshed collision models. The simulations are validated experimentally in planar rigid models using a pre-clinical electromagnetic navigation system. We also demonstrate the use of our framework to build training simulators for two endovascular navigation tasks including the exploration of the aortic arch and the internal carotid artery.

Using Magnetic Fields to Navigate and Simultaneously Localize Catheters in Endoluminal Environments

Remote magnetic navigation offers an ideal platform for automated catheter navigation. Magnetically guided catheters show great dexterity and can reach locations that are otherwise challenging to access. By automating aspects of catheterization procedures, we can simplify and expedite the procedure to allow surgeons to focus on other critical tasks during the surgery. In this article, we describe an automation strategy that is based on the center line of extracted and registered vascular geometries. Position feedback is accomplished with a Hall-effect sensor embedded near the distal end of the catheter. Sensor measurements are compared to the magnetic field predicted by a linear model of the electromagnetic navigation system. By defining specific magnetic field gradients and applying the known vascular geometry, the magnetic fields can be utilized for the simultaneous navigation and localization of the catheter. This eliminates the need for other external, dedicated mapping systems, and the use of fluoroscopy imaging is minimized. The concept is tested in 2d vascular models and the accuracy of the localization is assessed with overhead camera tracking.

Application of electromagnetic navigation in endoscopic transforaminal lumbar interbody fusion: a cohort study.

Clinical retrospective cohort study. To explore the application of the electromagnetic navigation system in Endo-TLIF. From May 2019 to March 2020, 76 patients with single-segment lumbar spondylolisthesis treated by electromagnetic navigation-assisted Endo-TLIF (NE group) and conventional Endo-TLIF (CE group) were enrolled in the study. Time of pediclescrew implantation, entire operation time, the number of intraoperative X-ray fluoroscopy exposures, total blood loss, incisionlength, ambulation time, accuracy of pedicle screws, complications, visual analog scale for back and leg pain, Oswestry Disability Index, Japanese Orthopedic Association score and postoperative fusion rates were recorded, respectively. There were no significant differences in preoperative demographics between the NE and CE groups (P > 0.05). The mean number of intraoperative X-ray fluoroscopy exposures, guidewires insertion, entire operation time, total blood loss and adjustment rate of screws in the NE group were significantly less compared with the CE group (P < 0.05, respectively). There were no significant differences in clinical parameters between the two groups at different time points in the follow-up period (P > 0.05). There was no statistical difference in fusion rates between the two groups. In addition, one case of cage subsidence was observed after surgery in the CE group. Electromagnetic navigation systems could be applied throughout the entire surgical course and ameliorate theshortcomingsofthe conventional Endo-TLIF technique to reduce radiation exposure, improve accuracy, avoid repetitive operations and shorten surgery time and the required learning curve of the procedure. Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding.

The "Eiffel Tower" technique: novel long-axis sacroplasty under electromagnetic navigation assistance; feasibility and descriptive study.

To describe a novel long-axis multimodal navigation assisted technique - the so-called Eiffel Tower technique - aimed at integrating recent technological improvements for the routine treatment of sacral insufficiency fractures. The long-axis approach described in the present study aimed at consolidating the sacral bone according to biomechanical considerations. The purpose was (i) to cement vertically the sacral alae all along and within the lateral fracture lines, resembling the pillars of a tower, and (ii) to reinforce cranially with a horizontal S1 landing zone (or dense central bone) resembling the first level of the tower. An electromagnetic navigation system was used in combination with CT and fluoroscopic guidance to overtop extreme angulation challenges. All patients treated between January 2019 and October 2021 in a single tertiary center were retrospectively reviewed. A description of the technique is provided. Twelve female patients (median age: 80 years [range: 32 to 94]) were treated for sacral insufficiency fractures with the "Eiffel Tower" technique. The median treatment delay was 8 weeks (range: 3 to 20) and the initial median pain assessed by the visual analogue scale was 7 (range: 6 to 8). Pain was successfully relieved (visual analogue score < 3) for 9 patients (75%) and persisted for 2 patients (17%). One patient was lost during the follow-up. No complication was noted. The "Eiffel Tower" multimodal cementoplasty integrates recent technological developments, in particular electromagnetic navigation, with the purpose of reconstructing the biomechanical chain of the sacral bone. • Sacral insufficiency fractures are common and can be efficiently treated with percutaneous sacroplasty. • The long axis sacroplasty approach can be challenging given both the shape of the sacral bone and the angulation to reach the target lesion. • The "Eiffel Tower" technique is a novel approach using electromagnetic navigation to expand the concept of the long axis route, adding a horizontal S1 landing zone.

A real-time 3D electromagnetic navigation system for percutaneous transforaminal endoscopic discectomy in patients with lumbar disc herniation: a retrospective study

BackgroundIn this study, we present a novel electromagnetic navigation (EMN) system for percutaneous transforaminal endoscopic discectomy (PTED) procedure. The objective of this study was to investigate the safety and effectiveness of the PTED with the assistance of the EMN system and compare it with the conventional PTED with the assistance of fluoroscopic guidance (C-arm).MethodsThe clinical data of 79 patients (32 in EMN group and 47 in C-arm group) undergoing PTED for lumbar disc herniation (LDH) from January to September of 2019 were analyzed retrospectively. The radiation time, puncture time, operation time, visual analog scale (VAS), Oswestry disability index (ODI), modified MacNab criteria, and radiological parameters were recorded in both groups.ResultsRadiation time, puncture time, and operation time were significantly reduced in the EMN group compared with the C-arm group (P < 0.05). Compared with the C-arm group, a steeper learning curve was observed in the EMN group. There were no significant differences between the two groups regarding VAS and ODI scores at different time points (P > 0.05). The satisfaction rates of the EMN and C-arm groups were 90.63 and 87.23%, respectively, but no significant difference was found between the two groups (P > 0.05). There was no significant difference regarding translation and angular motion between the two groups at preoperation and postoperation (P > 0.05).ConclusionsThe EMN system can be applied to facilitate the PETD procedure. It can significantly reduce the intraoperative radiation time, puncture time, and operation time, and reshape the learning curve of PTED. Due to limitations of a retrospective study, results may need validation with larger prospective randomized clinical trials.

Ultrasound-Based Navigation for Open Liver Surgery with Active Tumor Tracking and Deformation Compensation: Preliminary Results

Introduction: Intraoperative ultrasound (US) localization of lesions after neoadjuvant chemotherapy is challenging because their size may decrease beyond the ultrasound resolution. To improve their localization, we introduce an ultrasound-based electromagnetic (EM) navigation system which maps the preoperative image with the intraoperative ultrasound, thus highlighting their location. Methods: Based on MRI or CT, a 3D model of the liver, lesions, hepatic and portal vein was generated and matched with the intraoperative organ position either by 1) identifying common landmarks between the pre- and intraoperative image or 2) automatically using deformable modeling of hepatic and portal vasculature extracted from 3DUS using deep learning. Accuracy was assessed as Euclidean distance between the lesion imaged in the preoperative image and the one identified in intraoperative 3DUS. Results: From March 2019 to May 2021, 45 navigated procedures were safely performed. Navigation provided additional localization features by overlaying preoperative 3D models of liver lesions, vasculature and biliary anatomy onto the intraoperative ultrasound. Accuracy, calculated in 36 patients, was 8.5 ± 4.2 mm for the landmark method (n=20), and 5.7 ± 3.6 mm for automatic generation of the vasculature (n=16) (p=0.043). Surgical navigation was available on average after 13.4 minutes. Conclusion: The proposed navigation system allows to accurately localize liver lesions and is improved by automatic vasculature detection in the US image and compensation of respiratory motion and liver manipulation.

A Flexible Magnetically Controlled Continuum Robot Steering in the Enlarged Effective Workspace with Constraints for Retrograde Intrarenal Surgery

Magnetic Continuum Robots In article number 2000211, Niandong Jiao, Lianqing Liu, and co-workers propose a method of steering a miniaturized flexible magnetic continuum robot in the enlarged workspace of the electromagnetic navigation system. This method can greatly enlarge the effective workspace, and aims to expand the application of the magnetic continuum robot for retrograde intrarenal surgery.

Surgical Precision and Efficiency of a Novel Electromagnetic System Compared to a Robot-Assisted System in Percutaneous Pedicle Screw Placement of Endo-LIF.

Retrospective database study. To compare the accuracy and safety of 2 types of a computer-assisted navigation system for percutaneous pedicle screw placement during endoscopic lumbar interbody fusion. From May 2019 to January 2020, data of 56 patients who underwent Endo-LIF with a robot-assisted system and with an electromagnetic navigation system were compared. The pedicles in all patients were subjected to postoperative CT scan to assess screw correction by measuring the perpendicular distance between the pedicle cortical wall and the screw surface. The registration and matching time, guide-wire insertion time, the entire surgery time, and X-ray exposure time were recorded. In the robot-assisted group, 25 cases with 100 percutaneous pedicle screws were included, and the excellent and good rate was 95%. In the electromagnetic navigation group, 31 cases with 124 screws were included, and the excellent rate was 97.6%. There was no statistical difference between the two groups (P > 0.05). The registration time and the total time for the surgery also showed no statistical differences (P > 0.05). The main difference between the two groups was the guide-wire insertion time and the X-ray exposure time (P < 0.05). Both electromagnetic navigation and robot-assisted are safe and efficient for percutaneous pedicle screw placement. Electromagnetic navigation system has obvious advantages over robot-assisted in terms of faster guide-wire placement and less X-ray exposure. Robot-assisted for percutaneous pedicle screw placement offers a preoperative planning system and a stable registration system, with obvious drawbacks of a strict training curve.

A pilot study on the use of the super dimension navigation system for optimal cryobiopsy location in interstitial lung disease diagnostics

BackgroundTransbronchial cryobiopsies has become increasingly important in the diagnostic workup for interstitial lung diseases. The rate of complications and mortality are low compared to surgical lung biopsies, but the diagnostic yield is not as high. The reason for the lower diagnostic yield could in some cases be explained by biopsies taken too centrally or in less affected areas. In this pilot study we examined the feasibility of using the electromagnetic navigation system, superDimension (SD), when performing cryobiopsies to increase the diagnostic yield. MethodsElectromagnetic navigation bronchoscopy and cryobiopsies were performed using SD. An electromagnetic board placed on the back of the patient and a position sensor at the tip of the navigational probe created a real-time 3D reconstruction of previously acquired computer tomography images. The procedure was performed with the patients in general anesthesia using a rigid bronchoscope when performed in Florence and with a flexible bronchoscope through an orotracheal tube when performed in Aarhus. ResultsIn total, 18 patients were included. Five patients were excluded, partly due to technical difficulties. Disposable 1.7 mm cryoprobes were used in Aarhus, and reusable 1.9 mm probes in Florence. Pneumothorax was detected in three (23%), mild hemorrhage was seen in one (8%) and moderate hemorrhage in six (46%). The biopsies contributed to the diagnosis in 11 of the patients (85%). ConclusionUsing superDimension electromagnetic navigation system when performing cryobiopsies is feasible. A larger prospective trial is necessary to homogenize the technique between centres and to evaluate diagnostic advantage and complications.

Expert Consensus on Technical Specifications of Domestic Electromagnetic Navigation Bronchoscopy System in Diagnosis, Localization and Treatment (2021 Edition)

电磁导航支气管镜(electromagnetic navigation bronchoscopy, ENB)是以电磁定位技术为基础，结合虚拟支气管镜、三维计算机断层扫描(computed tomography, CT)成像和呼吸门控技术的新型支气管镜检查手段，该技术已在临床中广泛应用。近年来，国产电磁导航系统也得到了较快发展，其在肺外周病变诊断、定位和治疗中的有效性和安全性已得到初步验证，为优化和标准化国产ENB技术操作规范，指导其在临床实践中的应用，中国医学装备协会呼吸病学装备技术专业委员会和国产电磁导航支气管镜技术专家组组织专家讨论并制定了本专家共识。

A novel dynamic electromagnetic tracking navigation system for distal locking of intramedullary nails

BackgroundThe accurate distal locking of intramedullary (IM) nails is a clinical challenge for surgeons. Although many navigation systems have been developed, a real-time guide method with free radiation exposure, better user convenience, and high cost performance has not been proposed. MethodsThis paper aims to develop an electromagnetic navigation system named TianXuan-MDTS that provides surgeons with a proven surgical solution. And the registration method with external landmarks for IM nails and calibration algorithm for guiders were proposed. A puncture experiment, model experiments measured by 3D Slicer and cadaver experiments (2 cadaveric leg specimens and 6 drilling operations) are conducted to evaluate its performance and stability. ResultsThe registration deviations (TRE) is 1.05± 0.13 mm. In the puncture experiment, a success rate of 96% can be achieved in 45.94 s. TianXuan-MDTS were evaluated on 3 tibia model. The results demonstrated that all 9 screw holes were successfully prepared at a rate of 100% in 91.67 s. And the entry point, end point, and angular deviations were 1.60±0.20 mm, 1.47±0.18 mm, and 3.10±0.84°, respectively. Postoperative fluoroscopy in cadaver experiments showed that all drills were in the distal locking holes, with a success rate of 100% and the average time 143.17± 18.27 s. ConclusionsThe experimental results indicate that our system with novel registration and calibration methods could serve as a feasible and promising tool to assist surgeons during distal locking.

Clinical value of an electromagnetic navigation system for CT-guided percutaneous lung biopsy of peripheral lung lesions.

BackgroundThe purpose of this study was to retrospectively evaluate the clinical value of an electromagnetic navigation system for CT-guided percutaneous lung biopsy of peripheral lung lesions.MethodsThis was a retrospective study. Patients with peripheral lung lesions in our institution between January 2019 and December 2020, who underwent lung biopsy assisted by the electromagnetic navigation system were included in Group A, and those who underwent lung biopsy using conventional CT-guided percutaneous lung biopsy were included in Group B. The general features and clinical and technical information of each patient were collected and evaluated in both groups.ResultsA total of 141 patients were included in Group A (78 males and 63 females; median age, 65 years; range, 32–79 years), and 96 patients were included in group B (57 males and 39 females; median age, 65 years; range, 34–80 years). The technical success rate was 100% in both groups. The technical efficacy rate was 92.9% and 90.6% in Groups A and B (P=0.525), respectively. There was no significant difference in surgical time and the number of CT scans between the two groups, and only grade 1–2 complications occurred in the patients.ConclusionsThe electromagnetic navigation system is an effective and safe auxiliary tool for CT-guided percutaneous lung biopsy of peripheral lung lesions.

A real-time 3D electromagnetic navigation system for percutaneous pedicle screw fixation in traumatic thoraco-lumbar fractures: implications for efficiency, fluoroscopic time, and accuracy compared with those of conventional fluoroscopic guidance.

Navigation is becoming more useful in percutaneous pedicle screw fixation (PPSF). The aim of this study was to compare the efficiency, fluoroscopic time, accuracy, and clinical outcomes of PPSF with a novel electromagnetic navigation (EMN) system for thoraco-lumbar (TL) fractures with those of PPSF with conventional C-arm fluoroscopic (CF) guidance. A retrospective study was conducted. A total of 162 screws were implanted in 29 patients with the assistance of the EMN system (EMN group), and 220 screws were inserted in 40 patients by using CF guidance (CF group). The duration of surgery, placement time per screw, fluoroscopic time per screw, accuracy of pedicle screw placement, and clinical outcomes were compared between the two groups. The duration of surgery and placement time per screw in the EMN group were significantly lower than those in the CF group (P < 0.05). The fluoroscopic time per screw in the CF group was significantly longer than that in the EMN group (P < 0.05). The learning curve of PPSF in the EMN group was steeper than that in the CF group. The accuracy of pedicle screw placement in the EMN group was more precise than that in the CF group (P < 0.05). The VAS scores in the EMN group were significantly lower than those in the CF group at one-week postoperatively (P < 0.05). Compared with PPSF by using conventional fluoroscopic guidance, PPSF with the aid of the EMN system can increase the efficiency and accuracy of pedicle screw placement and reduce the fluoroscopic time.

A Submillimeter Continuous Variable Stiffness Catheter for Compliance Control.

Minimally invasive robotic surgery often requires functional tools that can change their compliance to adapt to the environment and surgical needs. This paper proposes a submillimeter continuous variable stiffness catheter equipped with a phase‐change alloy that has a high stiffness variation in its different states, allowing for rapid compliance control. Variable stiffness is achieved through a variable phase boundary in the alloy due to a controlled radial temperature gradient. This catheter can be safely navigated in its soft state and rigidified to the required stiffness during operation to apply a desired force at the tip. The maximal contact force that the catheter applies to tissue can be continuously modified by a factor of 400 (≈20 mN–8 N). The catheter is equipped with a magnet and a micro‐gripper to perform a fully robotic ophthalmic minimally invasive surgery on an eye phantom by means of an electromagnetic navigation system.

A Radiolucent Electromagnetic Tracking System for Use with Intraoperative X-ray Imaging.

In recent times, the use of electromagnetic tracking for navigation in surgery has quickly become a vital tool in minimally invasive surgery. In many procedures, electromagnetic tracking is used in tandem with X-ray technology to track a variety of tools and instruments. Most commercially available EM tracking systems can cause X-ray artifacts and attenuation due to their construction and the metals that form them. In this work, we provide a novel solution to this problem by creating a new radiolucent electromagnetic navigation system that has minimal impact on -ray imaging systems. This is a continuation of our previous work where we showed the development of the Anser open-source electromagnetic tracking system. Typical electromagnetic tracking systems operate by generating low frequency magnetic fields from coils that are located near the patient. These coils are typically made from copper, steel, and other dense radiopaque materials. In this work, we explore the use of low density aluminum to create these coils and we demonstrate that the effect on X-ray images is significantly reduced as a result of these novel changes in the materials used. The resulting field generator is shown to give at least a 60% reduction in the X-ray attenuation in comparison to our earlier designs. We verify that the system accuracy of approximately 1.5 mm RMS error is maintained with this change in design.

CT-guided vertebroplasty of first (C1) or second (C2) cervical vertebra using an electromagnetic navigation system and a transoral approach

CT-guided vertebroplasty of first (C1) or second (C2) cervical vertebra using an electromagnetic navigation system and a transoral approach

CBCT-based navigation system for open liver surgery: Accurate guidance toward mobile and deformable targets with a semi-rigid organ approximation and electromagnetic tracking of the liver.

PurposeThe surgical navigation system that provides guidance throughout the surgery can facilitate safer and more radical liver resections, but such a system should also be able to handle organ motion. This work investigates the accuracy of intraoperative surgical guidance during open liver resection, with a semi‐rigid organ approximation and electromagnetic tracking of the target area.MethodsThe suggested navigation technique incorporates a preoperative 3D liver model based on diagnostic 4D MRI scan, intraoperative contrast‐enhanced CBCT imaging and electromagnetic (EM) tracking of the liver surface, as well as surgical instruments, by means of six degrees‐of‐freedom micro‐EM sensors.ResultsThe system was evaluated during surgeries with 35 patients and resulted in an accurate and intuitive real‐time visualization of liver anatomy and tumor's location, confirmed by intraoperative checks on visible anatomical landmarks. Based on accuracy measurements verified by intraoperative CBCT, the system’s average accuracy was 4.0 ± 3.0 mm, while the total surgical delay due to navigation stayed below 20 min.ConclusionsThe electromagnetic navigation system for open liver surgery developed in this work allows for accurate localization of liver lesions and critical anatomical structures surrounding the resection area, even when the liver was manipulated. However, further clinically integrating the method requires shortening the guidance‐related surgical delay, which can be achieved by shifting to faster intraoperative imaging like ultrasound. Our approach is adaptable to navigation on other mobile and deformable organs, and therefore may benefit various clinical applications.

Electromagnetic navigation reduces radiation exposure for retrograde drilling in osteochondrosis dissecans of the talus

BackgroundRetrograde drilling in osteochondrosis dissecans (OCD) is a widely used surgical intervention. A radiation-free electromagnetic navigation system (ENS)-based method was compared with the standard freehand fluoroscopic (SFF) method regarding clinical applicability.MethodsWe performed a clinical cohort study at a department of Orthopaedics in a Level 1 children’s hospital with 40 patients (20 SFF and 20 ENS). Retrograde drilling of the talar dome was used in patients with unstable medial OCD (MRI stage 2 according to Hepple’s revised classification; stage 2 according to the International Cartilage Repair Society). The outcome measurements were: (a) Intraoperative fluoroscopy exposure and length of surgery and (b) Postoperative serial follow-up MRIs every 6 months.Results22 female and 18 male patients aged 13.8 ± 1.6 years (range: 11–17 years) were included. Using the ENS technique, length of surgery was significantly reduced to 20.2 ± 6.4 min compared to 36.1 ± 11.8 min (p < 0.01) for the SFF technique. The average x-ray radiation time for the SFF technique was 23.5 ± 13.5 sec and 1.9 ± 1.7 sec for the ENS technique (p < 0.01). Radiation exposure was significantly reduced from 44.6 ± 19.7 mSv (SFF technique) to 5.6 ± 2.8 mSv (ENS technique) (p < 0.01). Intraoperative perforation of cartilage occurred once in the SFF group. Correct placement of the drilling channel was verified in all patients on follow-up MRI after six months and a timely healing was seen after two years.ConclusionsThe ENS method provides for a significant reduction in length of surgery and radiation exposure. ENS was without intraoperative cartilage perforation. The clinical and radiological follow-up parameters are comparable for SFF- and ENS-guided retrograde drilling.Trial registrationWF – 085/20, 05/2020 “retrospectively registered” https://www.aerztekammer-hamburg.org/ethik_kommission.html.

Electromagnetic Navigation Systems and Intraoperative Neuromonitoring: Reliability and Feasibility Study.

A recent influx of intraoperative technology is being used in neurosurgery, but few reports investigate the accuracy and safety of these technologies when used simultaneously. To assess the ability to use an electromagnetic navigation system alongside multimodal intraoperative neurophysiological monitoring (IONM). Single-institution prospective cohort study of patients requiring craniotomy for brain tumor resection operated using an electromagnetic navigation system (AxiEM, Medtronic®). motor evoked potentials, somatosensory evoked potentials (SSEPs), electroencephalography, and electromyography were recorded and analyzed with AxiEM on (with/without filters) and off. The neurological outcomes of the patients were recorded. A total of 15 patients were included (8 males/7 females, mean age 52.13 yr). Even though the raw acquisition is affected by the electromagnetic field (particularly SSEPs), no significant difference was detected in the morphology, amplitude, and latency of the different monitoring modalities (AxiEM off vs on) after the appropriate software filter application. Adjustments to the frequency of SSEP stimulation and number of averages, and reductions to the low-pass filters were applied. Notch filters were used appropriately and changes to the physical setup of the IONM and electromagnetic navigation system equipment reduced noise. Postoperatively, none of the patients developed new focal deficits; 7 patients showed improvement in their motor deficit (4 recovered fully). The information provided by the IONM in intracranial neurosurgery patients whilst also using electromagnetic navigation systems is reliable for monitoring, mapping, and detecting intraoperative complications, provided that the appropriate software filters and tools are applied.

Real-Time Ultrasound Image Fusion with FDG-PET/CT to Perform Fused Image-Guided Fine-Needle Aspiration in Neck Nodes: Feasibility and Diagnostic Value.

New imaging techniques such as hybrid imaging of ultrasound and FDG-PET/CT are available but not yet investigated for node staging. The aim of the study was to evaluate the feasibility and added diagnostic value of real-time image-fused ultrasound-guided fine-needle aspiration with FDG-PET/CT data for node staging. Ninety-six patients who were referred for cervical lymph node staging with FDG-PET/CT before ultrasound were prospectively included. After routine ultrasound-guided fine-needle aspiration, all FDG-PET-positive nodes were marked on FDG-PET/CT, and real-time image fusing of ultrasound and FDG-PET/CT was performed using the electromagnetic navigation system PercuNav. Already-punctured nodes were confirmed to be PET-positive, and additional fused-ultrasound-guided fine-needle aspiration was performed in previously missed PET-positive nodes. Of 96 patients, 87 (91%) patients had suspicious nodes requiring fine-needle aspiration cytology. Ultrasound-guided fine-needle aspiration was performed in 175 nodes. Cytology was inconclusive in 9/175 (5%) nodes, and 85/166 (51%) nodes were malignant. Target planning was performed in 201 PET-positive nodes; 195/201 (97%) of those nodes were fused successfully. Twenty of 175 ultrasound-guided fine-needle aspiration nodes turned out to be FDG-PET-negative, and 149/175 (85%) of the fused ultrasound-guided fine-needle aspiration nodes were confirmed to be FDG-PET-positive. Of 201 PET-positive nodes, 46 (23%) were additionally identified, and fused ultrasound-guided fine-needle aspiration was performed. Cytology was inconclusive in 4/46 nodes (9%), and 13/42 (31%) nodes were malignant. Real-time ultrasound image fusion with FDG-PET-positive nodes is feasible in cervical lymph nodes, and fused ultrasound-guided fine-needle aspiration increases the number of malignant nodes detected.