scholarly journals Electromagnetic surgical navigation in patients undergoing mandibular surgery

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
S. G. Brouwer de Koning ◽  
F. Geldof ◽  
R. L. P. van Veen ◽  
M. J. A. van Alphen ◽  
L. H. E. Karssemakers ◽  
...  
Keyword(s):  
Surgical Navigation ◽  
Cone Beam Ct ◽  
Cone Beam ◽  
Patient Specific ◽  
Anatomical Landmarks ◽  
Target Registration Error ◽  
Patient Registration ◽  
Cutting Guide ◽  
Cutting Guides ◽  
Mandibular Surgery

AbstractThe purpose of this study was to evaluate the feasibility of electromagnetic (EM) navigation for guidance on osteotomies in patients undergoing oncologic mandibular surgery. Preoperatively, a 3D rendered model of the mandible was constructed from diagnostic computed tomography (CT) images. Cutting guides and patient specific reconstruction plates were designed and printed for intraoperative use. Intraoperative patient registration was performed using a cone beam CT scan (CBCT). The location of the mandible was tracked with an EM sensor fixated to the mandible. The real-time location of both the mandible and a pointer were displayed on the navigation system. Accuracy measurements were performed by pinpointing four anatomical landmarks and four landmarks on the cutting guide using the pointer on the patient and comparing these locations to the corresponding locations on the CBCT. Differences between actual and virtual locations were expressed as target registration error (TRE). The procedure was performed in eleven patients. TREs were 3.2 ± 1.1 mm and 2.6 ± 1.5 mm using anatomical landmarks and landmarks on the cutting guide, respectively. The navigation procedure added on average half an hour to the duration of the surgery. This is the first study that reports on the accuracy of EM navigation in patients undergoing mandibular surgery.

Evaluating an Image-Guided Operating Room with Cone Beam CT for Skull Base Surgery

2020 ◽  
Author(s):  
Nidal Muhanna ◽  
Catriona M. Douglas ◽  
Michael J. Daly ◽  
Harley H.L. Chan ◽  
Robert Weersink ◽  
...  
Keyword(s):  
Soft Tissue ◽  
Image Quality ◽  
Skull Base ◽  
Image Guidance ◽  
Surgical Navigation ◽  
Skull Base Surgery ◽  
Cone Beam Ct ◽  
Cone Beam ◽  
Anatomical Landmarks ◽  
Registration Error

Abstract Importance Skull base surgery requires precise preoperative assessment and intraoperative management of the patient. Surgical navigation is routinely used for complex skull base cases; however, the image guidance is commonly based on preoperative scans alone. Objective The primary objective of this study was to assess the image quality of intraoperative cone-beam computed tomography (CBCT) within anatomical landmarks used in sinus and skull base surgery. The secondary objective was to assess the registration error of a surgical navigation system based on intraoperative CBCT. Design Present study is a retrospective case series of image quality after intraoperative cone beam CT. Setting The study was conducted at Toronto General Hospital and Princess Margaret Cancer Centre, University Health Network, Toronto. Participants A total of 46 intraoperative scans (34 patients, 21 skull base, 13 head and neck) were studied. Main outcome and measures Thirty anatomical landmarks (vascular, soft tissue, and bony) within the sinuses and anterior skull base were evaluated for general image quality characteristics: (1) bony detail visualization; (2) soft-tissue visualization; (3) vascular visualization; and (4) freedom from artifacts (e.g., metal). Levels of intravenous (IV) contrast enhancement were quantified in Hounsfield's units (HU). Standard paired-point registration between imaging and tracker coordinates was performed using 6 to 8 skin fiducial markers and the corresponding fiducial registration error (FRE) was measured. Results Median score for bony detail on CBCT was 5, remaining at 5 after administration of IV contrast. Median soft-tissue score was 2 for both pre- and postcontrast. Median vascular score was 1 precontrast and 3 postcontrast. Median score for artifacts on CBCT were 2 for both pre-and postcontrast, and metal objects were noted to be the most significant source of artifact. Intraoperative CBCT allowed preresection images and immediate postresection images to be available to the skull base surgeon. There was a significant improvement in mean (standard deviation [SD]) CT intensity in the left carotid artery postcontrast 334 HU (67 HU) (p < 10−10). The mean FRE was 1.8 mm (0.45 mm). Conclusions Intraoperative CBCT in complex skull base procedures provides high-resolution bony detail allowing immediate assessment of complex resections. The use of IV contrast with CBCT improves the visualization of vasculature. Image-guidance based on CBCT yields registration errors consistent with standard techniques.

scholarly journals Imaging anatomy of the retrotympanum: variants and their surgical implications

2020 ◽  
Vol 93 (1105) ◽  
pp. 20190677 ◽  
Author(s):  
Christian Burd ◽  
Irumee Pai ◽  
Stephen Connor
Keyword(s):  
Cone Beam Ct ◽  
Cone Beam ◽  
Middle Ear Surgery ◽  
Anatomical Landmarks ◽  
Ear Surgery ◽  
Complex Anatomy ◽  
Pictorial Review ◽  
Operative Planning ◽  
Ct Technology ◽  
Temporal Bone Imaging

The retrotympanic anatomy is complex and variable but has received little attention in the radiological literature. With advances in CT technology and the application of cone beam CT to temporal bone imaging, there is now a detailed depiction of the retrotympanic bony structures. With the increasing use of endoscopes in middle ear surgery, it is important for the radiologist to appreciate the nomenclature of the retrotympanic compartments in order to aid communication with the surgeon. For instance, in the context of cholesteatoma, clear imaging descriptions of retrotympanic variability and pathological involvement are valuable in pre-operative planning. The endoscopic anatomy has recently been described and the variants classified. The retrotympanum is divided into medial and lateral compartments with multiple described potential sinuses separated by bony crests. This pictorial review will describe the complex anatomy and variants of the retrotympanum. We will describe optimum reformatting techniques to demonstrate the structures of the retrotympanum and illustrate the associated anatomical landmarks and variants with CT. The implications of anatomical variants with regards to otologic surgery will be discussed.

TH-D-BRC-05: Respiratory Motion Correction of Cone-Beam CT in Abdomen Using a Patient-Specific Motion Model

2009 ◽  
Vol 36 (6Part28) ◽  
pp. 2812-2812
Author(s):  
Q Zhang ◽  
YC Hu ◽  
S Kriminski ◽  
K Goodman ◽  
KE Rosenzweig ◽  
...  
Keyword(s):  
Motion Correction ◽  
Respiratory Motion ◽  
Cone Beam Ct ◽  
Cone Beam ◽  
Patient Specific ◽  
Motion Model ◽  
Respiratory Motion Correction

scholarly journals Imaging, Virtual Planning, Design, and Production of Patient-Specific Implants and Clinical Validation in Craniomaxillofacial Surgery

2012 ◽  
Vol 5 (3) ◽  
pp. 137-143 ◽  
Author(s):  
Per Dérand ◽  
Lars-Erik Rännar ◽  
Jan-M Hirsch
Keyword(s):  
Additive Manufacturing ◽  
Treatment Plan ◽  
Maxillofacial Surgery ◽  
Bone Substitutes ◽  
Patient Specific ◽  
Virtual Design ◽  
Patient Specific Implants ◽  
Cutting Guide ◽  
Ablative Surgery ◽  
Cutting Guides

The purpose of this article was to describe the workflow from imaging, via virtual design, to manufacturing of patient-specific titanium reconstruction plates, cutting guide and mesh, and its utility in connection with surgical treatment of acquired bone defects in the mandible using additive manufacturing by electron beam melting (EBM). Based on computed tomography scans, polygon skulls were created. Following that virtual treatment plans entailing free microvascular transfer of fibula flaps using patient-specific reconstruction plates, mesh, and cutting guides were designed. The design was based on the specification of a Compact UniLOCK 2.4 Large (Synthes®, Switzerland). The obtained polygon plates were bent virtually round the reconstructed mandibles. Next, the resections of the mandibles were planned virtually. A cutting guide was outlined to facilitate resection, as well as plates and titanium mesh for insertion of bone or bone substitutes. Polygon plates and meshes were converted to stereolithography format and used in the software Magics for preparation of input files for the successive step, additive manufacturing. EBM was used to manufacture the customized implants in a biocompatible titanium grade, Ti6Al4V ELI. The implants and the cutting guide were cleaned and sterilized, then transferred to the operating theater, and applied during surgery. Commercially available software programs are sufficient in order to virtually plan for production of patient-specific implants. Furthermore, EBM-produced implants are fully usable under clinical conditions in reconstruction of acquired defects in the mandible. A good compliance between the treatment plan and the fit was demonstrated during operation. Within the constraints of this article, the authors describe a workflow for production of patient-specific implants, using EBM manufacturing. Titanium cutting guides, reconstruction plates for fixation of microvascular transfer of osteomyocutaneous bone grafts, and mesh to replace resected bone that can function as a carrier for bone or bone substitutes were designed and tested during reconstructive maxillofacial surgery. A clinically fit, well within the requirements for what is needed and obtained using traditional free hand bending of commercially available devices, or even higher precision, was demonstrated in ablative surgery in four patients.

scholarly journals Fluoroscopic 3D Image Generation from Patient-Specific PCA Motion Models Derived from 4D-CBCT Patient Datasets: A Feasibility Study

2021 ◽  
Author(s):  
Salam Dhou ◽  
Mohanad Alkhodari ◽  
Dan Ionascu ◽  
Christopher Williams ◽  
John H. Lewis
Keyword(s):  
Vector Fields ◽  
Displacement Vector ◽  
Cone Beam Ct ◽  
Ground Truth ◽  
Absolute Error ◽  
Tumor Location ◽  
Cone Beam ◽  
Patient Specific ◽  
3D Image ◽  
Motion Models

A method for generating fluoroscopic (time-varying) volumetric images using patient-specific motion models derived from 4-dimensional cone-beam CT (4D-CBCT) images is developed. 4D-CBCT images acquired immediately prior to treatment have the potential to accurately represent patient anatomy and respiration during treatment. Fluoroscopic 3D image estimation is done in two steps: 1) deriving motion models and 2) optimization. To derive motion models, every phase in a 4D-CBCT set is registered to a reference phase chosen from the same set using deformable image registration (DIR). Principal components analysis (PCA) is used to reduce the dimensionality of the displacement vector fields (DVFs) resulting from DIR into a few vectors representing organ motion found in the DVFs. The PCA motion models are optimized iteratively by comparing a cone-beam CT (CBCT) projection to a simulated projection computed from both the motion model and a reference 4D-CBCT phase, resulting in a sequence of fluoroscopic 3D images. Patient datasets were used to evaluate the method by estimating the tumor location in the generated images compared to manually defined ground truth positions. Experimental results showed that the average tumor mean absolute error (MAE) along the superior-inferior (SI) direction and the 95th percentile in two patient datasets were (2.29 mm and 5.79 mm) for patient 1 and (1.89 mm and 4.82 mm) for patient 2. This study has demonstrated the feasibility of deriving 4D-CBCT-based PCA motion models that have the potential to account for the 3D non-rigid patient motion and localize tumors and other patient anatomical structures on the day of treatment.

TU-D-I-611-04: Intensity-Modulated Cone-Beam CT for Patient-Specific Distribution of SNR

2005 ◽  
Vol 32 (6Part16) ◽  
pp. 2092-2092 ◽  
Author(s):  
S Graham ◽  
J Siewerdsen ◽  
H Keller ◽  
D Moseley ◽  
D Jaffray
Keyword(s):  
Cone Beam Ct ◽  
Cone Beam ◽  
Patient Specific ◽  
Intensity Modulated ◽  
Specific Distribution

scholarly journals A learning-based method for online adjustment of C-arm Cone-beam CT source trajectories for artifact avoidance

2020 ◽  
Vol 15 (11) ◽  
pp. 1787-1796
Author(s):  
Mareike Thies ◽  
Jan-Nico Zäch ◽  
Cong Gao ◽  
Russell Taylor ◽  
Nassir Navab ◽  
...  
Keyword(s):  
Neural Network ◽  
Cone Beam Ct ◽  
Simulated Data ◽  
Tomographic Imaging ◽  
Cone Beam ◽  
Screw Placement ◽  
Patient Specific ◽  
Metal Artifacts ◽  
High Quality ◽  
Reconstruction Quality

Abstract Purpose During spinal fusion surgery, screws are placed close to critical nerves suggesting the need for highly accurate screw placement. Verifying screw placement on high-quality tomographic imaging is essential. C-arm cone-beam CT (CBCT) provides intraoperative 3D tomographic imaging which would allow for immediate verification and, if needed, revision. However, the reconstruction quality attainable with commercial CBCT devices is insufficient, predominantly due to severe metal artifacts in the presence of pedicle screws. These artifacts arise from a mismatch between the true physics of image formation and an idealized model thereof assumed during reconstruction. Prospectively acquiring views onto anatomy that are least affected by this mismatch can, therefore, improve reconstruction quality. Methods We propose to adjust the C-arm CBCT source trajectory during the scan to optimize reconstruction quality with respect to a certain task, i.e., verification of screw placement. Adjustments are performed on-the-fly using a convolutional neural network that regresses a quality index over all possible next views given the current X-ray image. Adjusting the CBCT trajectory to acquire the recommended views results in non-circular source orbits that avoid poor images, and thus, data inconsistencies. Results We demonstrate that convolutional neural networks trained on realistically simulated data are capable of predicting quality metrics that enable scene-specific adjustments of the CBCT source trajectory. Using both realistically simulated data as well as real CBCT acquisitions of a semianthropomorphic phantom, we show that tomographic reconstructions of the resulting scene-specific CBCT acquisitions exhibit improved image quality particularly in terms of metal artifacts. Conclusion The proposed method is a step toward online patient-specific C-arm CBCT source trajectories that enable high-quality tomographic imaging in the operating room. Since the optimization objective is implicitly encoded in a neural network trained on large amounts of well-annotated projection images, the proposed approach overcomes the need for 3D information at run-time.

scholarly journals Correction of motion artifacts in cone-beam CT using a patient-specific respiratory motion model

2010 ◽  
Vol 37 (6Part1) ◽  
pp. 2901-2909 ◽  
Author(s):  
Qinghui Zhang ◽  
Yu-Chi Hu ◽  
Fenghong Liu ◽  
Karyn Goodman ◽  
Kenneth E. Rosenzweig ◽  
...  
Keyword(s):  
Respiratory Motion ◽  
Cone Beam Ct ◽  
Motion Artifacts ◽  
Cone Beam ◽  
Patient Specific ◽  
Motion Model
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