Navigational Tools for Interventional Radiology and Interventional Oncology Applications

Abstract

The interventional radiologist is increasingly called upon to successfully access challenging biopsy and ablation targets, which may be difficult based on poor visualization, small size, or the proximity of vulnerable regional anatomy. Complex therapeutic procedures, including tumor ablation and transarterial oncologic therapies, can be associated with procedural risk, significant procedure time, and measurable radiation time. Navigation tools, including electromagnetic, optical, laser, and robotic guidance systems, as well as image fusion platforms, have the potential to facilitate these complex interventions with the potential to improve lesion targeting, reduce procedure time, and radiation dose, and thus potentially improve patient outcomes. This review will provide an overview of currently available navigational tools and their application to interventional radiology and oncology. A summary of the pertinent literature on the use of these tools to improve safety and efficacy of interventional procedures compared with conventional techniques will be presented.

Keywords: interventional oncology; interventional radiology; navigation; navigational tools; targeting.

Fig. 1

Equipment set up for electromagnetic device tracking during percutaneous interventions. Electromagnetic field generator (arrow) with sterile cover is positioned in proximity to the sterile field and directed toward anticipated needle entry site. Sterile fiducials (arrowheads) are placed on skin surface near anticipated skin entry site. (Reprinted with permission from Venkatesan et al.41)

Fig. 2

Pelvic biopsy facilitated by electromagnetic needle navigation and multimodality image fusion in a 19-year-old woman with undifferentiated round cell of the pelvis. (a) Axial PET/CT scan of pelvis demonstrates focus of FDG avidity within right iliopsoas muscle (arrow). Corresponding unenhanced CT scan (not shown) at the level of abnormal FDG-avid focus demonstrated a large osteolytic soft-tissue mass in the right hemipelvis involving right sacroiliac joint, but no focal anatomic abnormality to correspond to the patient's focus of FDG abnormality along the anterior aspect of this large soft-tissue mass within the right iliopsoas muscle. Intraprocedural CT scans coregistered to preacquired PET scans. Targeted focus of FDG avidity is displayed as a blue dot (arrow); tracked biopsy needle introducer is displayed as green line throughout the intervention. Intersecting red lines can be positioned to highlight either the location of the preselected target (b) or the tip of the tracked needle (c), as per the operator's preference, thereby adding visual conspicuity to either the target or tracked needle tip during the procedure. (d) CT scan confirms actual needle inserted to target immediately prior to sampling (arrowhead). Tracked biopsy facilitated by electromagnetic device tracking and image fusion confirmed necrotic round cell tumor (ghosts of round cells) and no evidence for viable malignancy. (Reprinted with permission from Venkatesan et al.41)

Fig. 3

Optical tracking using the Activiews CT-Guide needle guidance system (Activiews Ltd., Haifa, Israel now Stryker Corporation, Kalamazoo, MI). (a) A miniature video camera is attached to the needle or device. It identifies the CT-visible fiducial markers in a reference pad attached to the patient's skin. (b) A virtual line guides the probe accurately to the preplanned target, enabling two-dimensional (2D) planning in different planes and even (c) 3D planning. (Reprinted with permission from Appelbaum et al.24)

Fig. 4

Fig. 1 The Laser Navigation System (laser unit; circular rail; image processing unit). Laser guidance system is mounted in front of the CT intervention scanner (top image). Laser pointer displays the skin incision site (bottom left) and projects the predetermined trajectory angle along which the operator can manipulate a needle during lumbar puncture (bottom right image). (Reprinted with permission from Moser et al.15)

Fig. 5

Schematic demonstrating steps to obtain a magnetic resonance imaging/ultrasound (MRI/US) fusion-guided biopsy. ERC, endorectal coil; T2W, T2 weighted; DWI, diffusion-weighted imaging; DCE, dynamic contrast enhanced; TRUS, transrectal ultrasound; 3D, three dimensional. (Reprinted with permission from Minhaj et al. Magnetic Resonance Imaging/Ultrasound–Fusion Biopsy Significantly Upgrades Prostate Cancer Versus Systematic 12-core Transrectal Ultrasound Biopsy. European Urology 2013;64(5):713–719.)

Fig. 6

CT/US fusion for liver tumor ablation. (a) Coronal, axial, and sagittal views of a contrast-enhanced CT. The tumor and safety margin have been segmented (orange circles). The ablation zones required for complete coverage are also seen (blue circles). The target position for the ablation probe is depicted as the red cross. The virtual probe is seen as the purple line. As the operator advances the tracked probe, the “virtual” probe position adjusts in the software. (b) After the first ablation is completed, the ablation planning software updates the treated areas (as per manufacturer's specifications) shown as a purple circle. If applicable, the software also adjusts the position of subsequent probes seen as the red and purple crosses. The imaging can also be fused with ultrasound for real-time imaging guidance as seen on the left bottom screen. (Reprinted with permission from Abi-Jaoudeh et al.2)

Fig. 7

Patient with recurrent tumor and recent nondiagnostic biopsy. Graphical user interface showing metabolic activity (blue dots) on PET scan targeted with navigation to sample a viable part of the tumor. PET data were registered to procedural multiplanar reconstructed CT and procedural ultrasound for real-time feedback. Virtual needle represented by blue line. Multiplanar/multimodality navigation is displayed as well as down-the-needle-shaft view (lower left). (Reprinted with permission from Wood et al.3)

Fig. 8

CBCT imaging during Y90 workup in a 60-year-old patient suffering from chemorefractory colorectal liver metastases. (a and b) CBCT during hepatic arterial injection shows masses within the left hepatic lobe. (c) CBCT/fluoroscopic fusion shows catheter manipulation to target vessels. (d) Small hepatoenteric vessel feeding the right gastric wall (yellow arrow), which was not identified by angiography alone. Subsequently, proximal coil embolization of the right gastric artery was performed. (Reprinted with permission from Floridi et al.58)

Fig. 9

Prostate embolization using CBCT/fluoroscopy fusion. Prostate enhancement on delayed phase where segmentation was performed (top image). EmboGuide software (EmboGuide, Philips Healthcare, Best, The Netherlands) detected one right and one left prostatic artery (a and c) which were seen on 2D arteriography (b and d). (Reprinted with permission from Floridi et al.58)