Publications by authors named "Harley Chan"

70 Publications

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

J Neurol Surg B Skull Base 2021 Jul 3;82(Suppl 3):e306-e314. Epub 2020 Feb 3.

Department of Otolaryngology, Head and Neck Surgery, University of Toronto, Toronto, Canada.

 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.  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.  Present study is a retrospective case series of image quality after intraoperative cone beam CT.  The study was conducted at Toronto General Hospital and Princess Margaret Cancer Centre, University Health Network, Toronto.  A total of 46 intraoperative scans (34 patients, 21 skull base, 13 head and neck) were studied.  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.  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) (  < 10 ). The mean FRE was 1.8 mm (0.45 mm).  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.
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http://dx.doi.org/10.1055/s-0040-1701211DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8289492PMC
July 2021

Association of Plate Contouring With Hardware Complications Following Mandibular Reconstruction.

Laryngoscope 2021 Jun 24. Epub 2021 Jun 24.

Department of Otolaryngology - Head & Neck Surgery/Surgical Oncology, Princess Margaret Cancer Centre and Guided Therapeutics (GTx) Program, University of Toronto, Toronto, Ontario, Canada.

Objectives/hypothesis: Despite considerable effort being dedicated to contouring reconstruction plates, there remains limited evidence demonstrating an association between contour and reconstructive outcomes. We sought to evaluate whether optimizing mandibular reconstruction plate contouring is associated with reduced postoperative hardware complications.

Study Design: Retrospective cohort study.

Methods: A cohort study was performed with adult patients (age ≥18 years) who underwent mandibulectomy and osseous free flap reconstruction following oncologic ablation at the University Health Network in Toronto, Canada, between January 1, 2003 and December 31, 2014. Patients with computed tomography scans performed within 1 year of reconstruction were included. Computer-based three-dimensional models were generated and used to calculate the mean plate-to-bone gap (mm). The primary outcome was plate exposure. Secondary outcome included a composite of plate exposure or intraoral dehiscence. Logistic regression models were fitted for each outcome accounting for other patient and surgical characteristics associated with the primary outcome.

Results: Ninety-four patients met inclusion criteria, with a mean age of 60.4 (standard deviation [SD] 14.9). The mean follow-up time was 31.4 months (range 3-94). Reconstruction was performed with fibular (57%) and scapular free flaps (43%). In the multivariable model, small mean plate-to-bone gap (<1 mm) was independently associated with 86% reduced odds of plate exposure (odds ratio [OR] 0.12; 95% confidence interval [CI] 0.02-0.55). Mean plate-to-bone gap less than 1 mm was also independently associated with reduced odds of developing a composite of plate exposure or intraoral dehiscence (OR, 0.29; 95%CI, 0.11-0.75).

Conclusion: Optimizing plate contouring during mandibular reconstruction may decrease the development of postoperative hardware complications.

Level Of Evidence: IV Laryngoscope, 2021.
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http://dx.doi.org/10.1002/lary.29706DOI Listing
June 2021

tissue pathology from spatially encoded mass spectrometry classifiers visualized in real time through augmented reality.

Chem Sci 2020 Jul 23;11(33):8723-8735. Epub 2020 Jul 23.

Techna Institute for the Advancement of Technology for Health, University Health Network 100 College Street, Room 7-207, MaRS Building, Princess Margaret Cancer Research Tower, 7th floor (STTARR) Toronto ON M5G 1P5 Canada +1-416-581-8473.

Integration between a hand-held mass spectrometry desorption probe based on picosecond infrared laser technology (PIRL-MS) and an optical surgical tracking system demonstrates tissue pathology from point-sampled mass spectrometry data. Spatially encoded pathology classifications are displayed at the site of laser sampling as color-coded pixels in an augmented reality video feed of the surgical field of view. This is enabled by two-way communication between surgical navigation and mass spectrometry data analysis platforms through a custom-built interface. Performance of the system was evaluated using murine models of human cancers sampled in the presence of body fluids with a technical pixel error of 1.0 ± 0.2 mm, suggesting a 84% or 92% (excluding one outlier) cancer type classification rate across different molecular models that distinguish cell-lines of each class of breast, brain, head and neck murine models. Further, through end-point immunohistochemical staining for DNA damage, cell death and neuronal viability, spatially encoded PIRL-MS sampling is shown to produce classifiable mass spectral data from living murine brain tissue, with levels of neuronal damage that are comparable to those induced by a surgical scalpel. This highlights the potential of spatially encoded PIRL-MS analysis for use during neurosurgical applications of cancer type determination or point-sampling tissue during tumor bed examination to assess cancer removal. The interface developed herein for the analysis and the display of spatially encoded PIRL-MS data can be adapted to other hand-held mass spectrometry analysis probes currently available.
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http://dx.doi.org/10.1039/d0sc02241aDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8163395PMC
July 2020

Determination of Optical Properties and Photodynamic Threshold of Lung Tissue for Treatment Planning of In Vivo Lung Perfusion Assisted Photodynamic Therapy.

Photodiagnosis Photodyn Ther 2021 May 26;35:102353. Epub 2021 May 26.

University of Toronto, Faculty of Medicine, Department of Medical Biophysics, 101 College Street, Toronto M5G 1L7, Ontario, Canada; Princess Margaret Cancer Centre, University Health Network, 101 College St, Toronto M5G 2C4, Ontario, Canada. Electronic address:

Background: Isolated lung metastases in sarcoma and colorectal cancer patients are inadequately treated with current standard therapies. In Vivo Lung Perfusion, a novel platform, could overcome limitations to photodynamic therapy treatment volumes by using low cellular perfusate, removing blood, theoretically allowing greater light penetration. To develop personalized photodynamic therapy protocols requires in silico light propagation simulations based on optical properties and maximal permissible photodynamic threshold dose of lung tissue. This study presents quantification of optical properties for two perfusates and the photodynamic threshold for 5-ALA and Chlorin e6.

Methods: Porcine and human lungs were placed on Ex Vivo Lung Perfusion, and perfused with acellular solution or blood. Isotropic diffusers were placed within bronchi and on lung surface for light transmission measurements, from which absorption and light scattering properties were calculated at multiple wavelengths. Separately, pigs were injected with 5-ALA or Chlorin e6, and lung tissue was irradiated at increasing doses. Resultant lesion sizes were measured by CT and histology to quantify the photodynamic threshold.

Results: Low cellular perfusate reduced the tissue absorption coefficient significantly, increasing penetration depth of light by 3.3 mm and treatment volumes 3-fold. The photodynamic threshold for lung exposed to 5-ALA was consistent with other malignancies. Chlorin e6 levels were undetectable in lung tissue and did not demonstrate photodynamic-induced necrosis.

Conclusions: Light penetration with low cellular perfusate is significantly greater and could enable treatments for diffuse disease. This data aids photodynamic treatment planning and will guide clinical translation of photodynamic therapy protocols in the lung, especially during lung perfusion.
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http://dx.doi.org/10.1016/j.pdpdt.2021.102353DOI Listing
May 2021

An integrated augmented reality surgical navigation platform using multi-modality imaging for guidance.

PLoS One 2021 30;16(4):e0250558. Epub 2021 Apr 30.

TECHNA Institute, University Health Network, Toronto, ON, Canada.

An integrated augmented reality (AR) surgical navigation system that potentially improves intra-operative visualization of concealed anatomical structures. Integration of real-time tracking technology with a laser pico-projector allows the surgical surface to be augmented by projecting virtual images of lesions and critical structures created by multimodality imaging. We aim to quantitatively and qualitatively evaluate the performance of a prototype interactive AR surgical navigation system through a series of pre-clinical studies. Four pre-clinical animal studies using xenograft mouse models were conducted to investigate system performance. A combination of CT, PET, SPECT, and MRI images were used to augment the mouse body during image-guided procedures to assess feasibility. A phantom with machined features was employed to quantitatively estimate the system accuracy. All the image-guided procedures were successfully performed. The tracked pico-projector correctly and reliably depicted virtual images on the animal body, highlighting the location of tumour and anatomical structures. The phantom study demonstrates the system was accurate to 0.55 ± 0.33mm. This paper presents a prototype real-time tracking AR surgical navigation system that improves visualization of underlying critical structures by overlaying virtual images onto the surgical site. This proof-of-concept pre-clinical study demonstrated both the clinical applicability and high precision of the system which was noted to be accurate to <1mm.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0250558PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8087077PMC
April 2021

Objective evaluation of orbito-zygomatic reconstruction with scapular tip free flaps to restore facial projection and orbital volume.

Oral Oncol 2021 Jun 10;117:105268. Epub 2021 Apr 10.

Department of Otolaryngology - Head and Neck Surgery/Surgical Oncology, Princess Margaret Cancer Centre/University Health Network, Toronto, Ontario, Canada. Electronic address:

Background: Restoring anatomical contour and position of the malar eminence and orbital rim following ablative mid-face procedures is critical in maintaining facial contour and orbit position.

Objective: To report our reconstructive approach using the scapular tip free-flap (STFF) for orbito-zygomatic defects, evaluating contour and overall shape restoration.

Methods: The study included 2 series: a clinical cohort of 15 consecutive patients who underwent an orbito-zygomatic reconstruction with a STFF and a cohort of 10 patients who had CT scan imaging but did not have orbito-zygomatic surgical resection or reconstruction. Using a 3D software, overall conformance (OC) and contour conformance (CC) with respect to the mirrored contralateral (clinical cohort) or native zygoma (preclinical cohort) were analyzed. Postoperative orbital volumes were also measured in the clinical cohort. Mean, median, root-mean-square (RMS), minimum and maximum measurements were obtained both for OC and CC. Conformance values of clinical and preclinical cohort were compared to objectively evaluate the quality of reconstruction in terms of orbito-zygomatic framework restoration (Mann-Whitney test).

Results: All measurements for OC and CC between scapular tip and the zygoma showed no differences, both on the clinical (RMS: OC 3.29 mm vs CC 3.32 mm -p = NS-) and preclinical (RMS: OC 2.03 mm and CC 2.31 mm -p = NS-) cohorts. Moreover, there were no differences in post-operative orbital volumes in the clinical cohort. Clinical outcomes of the case-series are also reported.

Conclusion: The STFF is highly effective in restoring facial projection and orbital volume in orbito-zygomatic reconstruction.
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http://dx.doi.org/10.1016/j.oraloncology.2021.105268DOI Listing
June 2021

Developing a virtual reality simulation system for preoperative planning of thoracoscopic thoracic surgery.

J Thorac Dis 2021 Feb;13(2):778-783

Division of Thoracic Surgery, Toronto General Hospital, University Health Network, University of Toronto, Toronto, ON, Canada.

Background: Video-assisted thoracoscopic surgery (VATS) has become a standard approach for the treatment of lung cancer. However, its minimally invasive nature limits the field of view and reduces tactile feedback. These limitations make it vital that surgeons thoroughly familiarize themselves with the patient's anatomy preoperatively. We have developed a virtual reality (VR) surgical navigation system using head-mounted displays (HMD). The aim of this study was to investigate the potential utility of this VR simulation system in both preoperative planning and intraoperative assistance, including support during thoracoscopic sublobar resection.

Methods: Three-dimensional (3D) polygon data derived from preoperative computed tomography data was loaded into BananaVision software developed at Colorado State University and displayed on an HMD. An interactive 3D reconstruction image was created, in which all the pulmonary structures could be individually imaged. Preoperative resection simulations were performed with patient-individualized reconstructed 3D images.

Results: The 3D anatomic structure of pulmonary vessels and a clear vision into the space between the lesion and adjacent tissues were successfully appreciated during preoperative simulation. Surgeons could easily evaluate the real patient's anatomy in preoperative simulations to improve the accuracy and safety of actual surgery. The VR software and HMD allowed surgeons to visualize and interact with real patient data in true 3D providing a unique perspective.

Conclusions: This initial experience suggests that a VR simulation with HMD facilitated preoperative simulation. Routine imaging modalities combined with VR systems could substantially improve preoperative planning and contribute to the safety and accuracy of anatomic resection.
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http://dx.doi.org/10.21037/jtd-20-2197DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7947494PMC
February 2021

Comparing Contour Restoration of Mandibular Body Defects With Fibula, Iliac Crest, and Scapular Tip Flaps: A Conformance Virtual Study.

J Oral Maxillofac Surg 2021 06 29;79(6):1345-1354. Epub 2020 Dec 29.

Professor, Department of Otolaryngology - Head and Neck Surgery/Surgical Oncology, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada; and Guided Therapeutics (GTx) Program, Techna Institute, University Health Network, Toronto, Ontario, Canada.

Purpose: The purpose of this study was to determine which of the most commonly used flaps restore contour more accurately in mandibular body reconstructions using conformance analyses and virtual measurements.

Methods: Using normal computed tomography (CT) scans and a 3D software, mandibular body defects were virtually created. "Single shot" and osteotomized fibula flaps (SS-FF and O-FF), iliac crest flaps (ICF) and scapular tip flaps (STF) were digitally harvested and coregistered to reconstruct those defects. Conformance analyses were performed by calculating the root mean square (RMS) for overall and contour conformance.

Results: Ten patients normal CT scans were included. The STF demonstrated improved overall conformance compared with the ICF, the SS-FF and the O-FF (RMS = 2.03 mm vs 4.53 mm vs 2.76 vs 2.37 mm, respectively; p<.001). Similar trends were seen for contour conformance in STF compared with the ICF and the SS-FF (RMS = 2.48 mm vs 4.50 mm vs 3.28 mm, respectively), whereas the O-FF performed better than STF (RMS = 1.85 mm vs 2.48 mm; p<.001).

Conclusions: The osseous component of the STF resembles the mandibular body more accurately than the one in the ICF and FF without the need for an osteotomy. Future clinical studies can help to elucidate the clinical impact of these virtual findings.
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http://dx.doi.org/10.1016/j.joms.2020.12.031DOI Listing
June 2021

Assessment of a liposomal CT/optical contrast agent for image-guided head and neck surgery.

Nanomedicine 2021 02 19;32:102327. Epub 2020 Nov 19.

Princess Margaret Cancer Centre and University Health Network, TECHNA Institute, Guided Therapeutic (GTx) Program, Toronto, ON, Canada.; Department of Otolaryngology-Head and Neck Surgery-Surgical Oncology, Princess Margaret Cancer Centre/University Health Network, University of Toronto, Toronto, ON, Canada.. Electronic address:

This study evaluates a long-acting liposomal fluorescence / CT dual-modality contrast agent (CF800) in head and neck cancer to enhance intraoperative tumor demarcation with fluorescence imaging and cone-beam computed tomography (CBCT). CF800 was administered to 12 buccal cancer-bearing rabbits. Imaging was acquired at regular time points to quantify time-dependent contrast enhancement. Surgery was performed 5-7 days after, with intraoperative near-infrared fluorescence endoscopy and CBCT, followed by histological and ex-vivo fluorescence assessment. Tumor enhancement on CT was significant at 24, 96 and 120 hours. Volumetric analysis of tumor segmentation showed high correlation between CBCT and micro-CT. Fluorescence signal was apparent in both ex-vivo and in-vivo imaging. Histological correlation showed [100%] specificity for primary tumor. Sensitivity and specificity of CF800 in detecting nodal involvement require further investigation.CF800 is long acting and has dual function for CT and fluorescence contrast, making it an excellent candidate for image-guided surgery.
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http://dx.doi.org/10.1016/j.nano.2020.102327DOI Listing
February 2021

Sentinel lymph node mapping using ICG fluorescence and cone beam CT - a feasibility study in a rabbit model of oral cancer.

BMC Med Imaging 2020 09 14;20(1):106. Epub 2020 Sep 14.

Department of Otolaryngology - Head & Neck Surgery, University of Toronto, Toronto, ON, Canada.

Background: Current sentinel lymph node biopsy (SLNB) techniques, including use of radioisotopes, have disadvantages including the use of a radioactive tracer. Indocyanine green (ICG) based near-infrared (NIR) fluorescence imaging and cone beam CT (CBCT) have advantages for intraoperative use. However, limited literature exists regarding their use in head and neck cancer SLNB.

Methods: This was a prospective, non-randomized study using a rabbit oral cavity VX2 squamous cell carcinoma model (n = 10) which develops lymph node metastasis. Pre-operatively, images were acquired by MicroCT. During surgery, CBCT and NIR fluorescence imaging of ICG was used to map and guide the SLNB resection.

Results: Intraoperative use of ICG to guide fluorescence resection resulted in identification of all lymph nodes identified by pre-operative CT. CBCT was useful for near real time intraoperative imaging and 3D reconstruction.

Conclusions: This pre-clinical study further demonstrates the technical feasibility, limitations and advantages of intraoperative NIR-guided ICG imaging for SLN identification as a complementary method during head and neck surgery.
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http://dx.doi.org/10.1186/s12880-020-00507-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7491106PMC
September 2020

Nasal Endoscopy During the COVID-19 Pandemic: Mitigating Risk with 3D Printed Masks.

Laryngoscope 2020 11 20;130(11):2561-2563. Epub 2020 Aug 20.

Department of Otolaryngology-Head & Neck Surgery/Surgical Oncology, Princess Margaret Cancer Centre and Guided Therapeutics Program, University of Toronto, Toronto, Ontario, Canada.

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http://dx.doi.org/10.1002/lary.29004DOI Listing
November 2020

Scapular tip-thoracodorsal artery perforator free flap for total/subtotal glossectomy defects: Case series and conformance study.

Oral Oncol 2020 06 31;105:104660. Epub 2020 Mar 31.

Department of Otolaryngology - Head and Neck Surgery/Surgical Oncology, University Health Network, Toronto, Ontario, Canada. Electronic address:

Background: Reconstruction of the tongue and floor of mouth after total/subtotal glossectomy poses a major challenge for reconstructive surgeons. Speech and deglutition after total glossectomy are usually significantly impaired, affecting the quality of life of these patients. Maintaining an adequate volume of the reconstruction is paramount to optimize speech and swallowing function postoperatively.

Aim: To report a novel free flap reconstructive technique based on the subscapular system.

Methods: A preliminary cases series of patients undergoing reconstruction with scapular tip-thoracodorsal artery perforator (STTDAP) flap after total/subtotal glossectomy is reported. Conformance of the scapular tip with respect to the inner aspect of the mandible is measured in a sample of 10 subjects (20 sides) with normal scapular and mandibular anatomy, considering both the entirety of the scapular tip (overall conformance) and its caudal border (border conformance). Association between scapular morphology and conformance to the mandible was assessed statistically.

Results: Three patients matched inclusion criteria. Mean follow-up was 7 months. Speech and deglutition result was satisfactory in 2 patients and poor in 1 patient. Overall and border conformance were high (root mean square: 2.23 mm and 3.14 mm, respectively). Shape and angular aperture of the scapular tip significantly affected overall and border conformance, respectively.

Conclusion: Reconstruction of the tongue with STTDAP flap after total glossectomy is feasible. Conformance between the scapular tip and mandible is optimal and, although based on preliminary evidence, patients might benefit from this technique in terms of functional outcomes.
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http://dx.doi.org/10.1016/j.oraloncology.2020.104660DOI Listing
June 2020

Endobronchial Ultrasound-Guided Radiofrequency Ablation of Lung Tumors and Mediastinal Lymph Nodes: A Preclinical Study in Animal Lung Tumor and Mediastinal Adenopathy Models.

Semin Thorac Cardiovasc Surg 2020 Autumn;32(3):570-578. Epub 2020 Feb 10.

Division of Thoracic Surgery, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada; TECHNA Institute for the Advancement of Technology for Health, University Health Network, Toronto, Ontario, Canada.

Radiofrequency ablation (RFA) can be a therapeutic option in medically inoperable lung cancer patients. In this study, we evaluated a prototype bipolar RFA device applicator that can be deployed from a standard endobronchial ultrasound (EBUS) bronchoscope to determine feasibility and histopathological analysis in animal models. Rabbit lung cancers were created by transbronchial injection of VX2 rabbit cancer cells. Once the tumors were developed, they were ablated transpleurally, under EBUS guidance using the prototype RFA device. The animals were then sacrificed for specimen resection. Pig inflammatory lung pseudo-tumors and lymphadenopathy were created by transbronchial injection of a talc paste and ablated transbronchially under EBUS guidance. Pigs were evaluated at 5 days, 2 weeks, and 4 weeks following ablation by bronchoscopy and cone beam computed tomography before necropsy. Nicotinamide adenine dinucleotide hydrogen diaphorase staining was employed to measure the ablation area. Twenty-four VX2 rabbit tumors were ablated. The total ablated area ranged from 0.6 to 3.0 cm (mean: 1.8 cm), corresponding to a total energy range of 1 to 6 kJ. Six pig lung pseudo-tumors and 5 mediastinal lymph nodes were ablated. Adjacent airway ulceration was observed in 3 ablations of lymph nodes. These airway complications resolved within 4 weeks of RFA without any treatment. There was no hemoptysis, air embolism, respiratory distress, or other serious complication noted. In these 2 animal models, we provide evidence that EBUS-guided bipolar RFA is feasible and histopathology shows that can ablate lung tumors and mediastinal lymph nodes under real-time ultrasound guidance.
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http://dx.doi.org/10.1053/j.semtcvs.2020.02.003DOI Listing
October 2020

Establishing Orbital Floor Symmetry to Support Mirror Imaging in Computer-Aided Reconstruction of the Orbital Floor.

J Craniofac Surg 2019 Sep;30(6):1888-1890

Department of Otolaryngology - Head and Neck Surgery/Surgical Oncology.

Background: Surgical precision in the reconstruction of the orbital floor is crucial to functional visual and aesthetic outcomes. Increasingly, computer-aided design is being utilized to aid in precise preoperative planning by using the mirror images of the unaffected side. The authors aim to use 3-dimensional (3D) quantitative analysis to establish whether the native orbital floor topography is sufficiently symmetric to support this practice.

Methods: Ten high resolution head and neck computed tomography scans of patients without periorbital pathology were obtained. These were imported into a 3D medical image processing software and segmented to isolate bilateral orbital floors. Each native orbital floor was compared to the mirror image of the contralateral side by conformance map computation. Data collection included measures of 25% and 75% quartile, median, mean, standard deviation, and root-mean-square (RMS).

Results: The topographic analysis demonstrated a high degree of topographic conformance with a mean RMS of 0.58 ± 0.37 mm. Further volumetric analysis comparing the total orbital volume between each side also demonstrates a high degree of volumetric symmetry with a mean difference of 0.55 mL (P = 0.30).

Conclusion: Comparison of the native orbital floor and the mirror image of the contralateral side by conformance map computation and volumetric analysis demonstrated a high degree of morphologic similarity. The native orbital floor topography provides optimal symmetry to support mirror imaging techniques used in orbital floor reconstruction.
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http://dx.doi.org/10.1097/SCS.0000000000005368DOI Listing
September 2019

Cone beam CT for perioperative imaging in hearing preservation Cochlear implantation - a human cadaveric study.

J Otolaryngol Head Neck Surg 2019 Nov 21;48(1):65. Epub 2019 Nov 21.

Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Ave., Room M1, Toronto, 102, Canada.

Background: Knowledge of the cochlear implant array's precise position is important because of the correlation between electrode position and speech understanding. Several groups have provided recent image processing evidence to determine scalar translocation, angular insertion depth, and cochlear duct length (CDL); all of which are being used for patient-specific programming. Cone beam computed tomography (CBCT) is increasingly used in otology due to its superior resolution and low radiation dose. Our objectives are as followed: 1.Validate CBCT by measuring cochlear metrics, including basal turn diameter (A-value) and lateral wall cochlear duct length at different angular intervals and comparing it against microcomputed CT (uCT).2.Explore the relationship between measured lateral wall cochlear duct length at different angular intervals and insertion depth among 3 different length electrodes using CBCT.

Methods: The study was performed using fixed human cadaveric temporal bones in a tertiary academic centre. Ten temporal bones were subjected to the standard facial recess approach for cochlear implantation and imaged by CBCT followed by uCT. Measurements were performed on a three-dimensional reconstructed model of the cochlea. Sequential insertion of 3 electrodes (Med-El Flex24, 28 and Soft) was then performed in 5 bones and reimaged by CBCT. Statistical analysis was performed using Pearson's correlation.

Results: There was good agreement between CBCT and uCT for cochlear metrics, validating the precision of CBCT against the current gold standard uCT in imaging. The A-value recorded by both modalities showed a high degree of linear correlation and did not differ by more than 0.23 mm in absolute values. For the measurement of lateral wall CDL at various points along the cochlea, there was a good correlation between both modalities at 360 deg and 720 deg (r = 0.85, p < 0.01 and r = 0.79, p < 0.01). The Flex24 electrode displayed consistent insertion depth across different bones.

Conclusions: CBCT reliably performs cochlear metrics and measures electrode insertion depth. The low radiation dose, fast acquisition time, diminished metallic artifacts and portability of CBCT make it a valid option for imaging in cochlear implant surgery.
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http://dx.doi.org/10.1186/s40463-019-0388-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6873551PMC
November 2019

Photodynamic therapy enables tumor-specific ablation in preclinical models of thyroid cancer.

Endocr Relat Cancer 2020 02;27(2):41-53

Guided Therapeutic (GTx) Program, TECHNA Institute, Princess Margaret Cancer Center and University Health Network, Toronto, Ontario, Canada.

The incidence of differentiated thyroid cancer has increased significantly during the last several decades. Surgical resection is the primary treatment for thyroid cancer and is highly effective, resulting in 5-year survival rates greater than 98%. However, surgical resection can result in short- and long-term treatment-related morbidities. Additionally, as this malignancy often affects women less than 40 years of age, there is interest in more conservative treatment approaches and, an unmet need for therapeutic options that minimize the risk of surgery-related morbidities while simultaneously providing an effective cancer treatment. Photodynamic therapy (PDT) has the potential to reduce treatment-related side effects by decreasing invasiveness and limiting toxicity. Owing to multiple advantageous properties of the porphyrin-HDL nanoparticle (PLP) as a PDT agent, including preferential accumulation in tumor, biodegradability and unprecedented photosensitizer packing, we evaluate PLP-mediated PDT as a minimally invasive, tumor-specific treatment for thyroid cancer. On both a biologically relevant human papillary thyroid cancer (K1) mouse model and an anatomically relevant rabbit squamous carcinoma (VX2)-implanted rabbit thyroid model, the intrinsic fluorescence of PLP enabled tracking of tumor preferential accumulation and guided PDT. This resulted in significant and specific apoptosis in tumor tissue, but not surrounding normal tissues including trachea and recurrent laryngeal nerve (RLN). A long-term survival study further demonstrated that PLP-PDT enabled complete ablation of tumor tissue while sparing both the normal thyroid tissue and RLN from damage, thus providing a safe, minimally invasive, and effective alternative to thyroidectomy for thyroid cancer therapies.
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http://dx.doi.org/10.1530/ERC-19-0258DOI Listing
February 2020

Navigation-guided osteotomies improve margin delineation in tumors involving the sinonasal area: A preclinical study.

Oral Oncol 2019 12 1;99:104463. Epub 2019 Nov 1.

Department of Otolaryngology - Head and Neck Surgery/Surgical Oncology, Princess Margaret Cancer Centre/University Health Network, Toronto, Ontario, Canada; Guided Therapeutics (GTx) Program, Techna Institute, University Health Network, Toronto, Ontario, Canada. Electronic address:

Objectives: To demonstrate and quantify, in a preclinical setting, the benefit of three-dimensional (3D) navigation guidance for margin delineation during ablative open surgery for advanced sinonasal cancer.

Materials And Methods: Seven tumor models were created. 3D images were acquired with cone beam computed tomography, and 3D tumor segmentations were contoured. Eight surgeons with variable experience were recruited for the simulation of osteotomies. Three simulations were performed: 1) Unguided, 2) Guided using real-time tool tracking with 3D tumor segmentation (tumor-guided), and 3) Guided by 3D visualization of both the tumor and 1-cm margin segmentations (margin-guided). Analysis of cutting planes was performed and distance from the tumor surface was classified as follows: "intratumoral" when 0 mm or negative, "close" when greater than 0 mm and less than or equal to 5 mm, "adequate" when greater than 5 mm and less than or equal to 15 mm, and "excessive" over 15 mm. The three techniques (unguided, tumor-guided, margin-guided) were statistically compared.

Results: The use of 3D navigation for margin delineation significantly improved control of margins: unguided cuts had 18.1% intratumoral cuts compared to 0% intratumoral cuts with 3D navigation (p < 0.0001).

Conclusion: This preclinical study has demonstrated the significant benefit of navigation-guided osteotomies for sinonasal tumors. Translation into the clinical setting - with rigorous assessment of oncological outcomes - would be the proposed next step.
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http://dx.doi.org/10.1016/j.oraloncology.2019.104463DOI Listing
December 2019

An Orthotopic Endometrial Cancer Model with Retroperitoneal Lymphadenopathy Made From In Vivo Propagated and Cultured VX2 Cells.

J Vis Exp 2019 09 12(151). Epub 2019 Sep 12.

Department of Medical Biophysics, University of Toronto; Princess Margaret Cancer Center, University Health Network;

Endometrial cancer is the most common gynecologic malignancy in North America and the incidence is rising worldwide. Treatment consists of surgery with or without adjuvant therapy depending on lymph node involvement as determined by lymphadenectomy. Lymphadenectomy is a morbid procedure, which has not been shown to have a therapeutic benefit in many patients, and thus a new method to diagnose lymph node metastases is required. To test novel imaging agents, a reliable model of endometrial cancer with retroperitoneal lymph node metastases is needed. The VX2 endometrial cancer model has been described frequently in the literature; however, significant variation exists with respect to the method of model establishment. Furthermore, no studies have reported on the use of cultured VX2 cells to create this model as only cells propagated in vivo have been previously used. Herein, we present a standardized surgical method and post-operative monitoring method for the establishment of the VX2 endometrial cancer model and report on the first use of cultured VX2 cells to create this model.
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http://dx.doi.org/10.3791/59340DOI Listing
September 2019

Quantitative Analysis of Surgical Working Space During Endoscopic Skull Base Surgery.

J Neurol Surg B Skull Base 2019 Oct 26;80(5):469-473. Epub 2018 Nov 26.

Li Ka Shing Knowledge Institute, St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada.

 Selective dissection of intranasal anatomy may improve visualization and maneuverability at the skull base. We aimed to quantify the dimensions of working space and angles achieved following sequential removal of intranasal structures using an endoscopic transphenoidal approach to the skull base.  Cone beam computed tomography scans of four cadaveric heads were obtained for registration of an optical tracking system. Each head was sequentially dissected: (1) sphenoidotomy and limited posterior septectomy, (2) unilateral partial middle turbinectomy, (3) bilateral partial middle turbinectomy, and (4) wide posterior septectomy. The maximal craniocaudal and mediolateral distance (mm) and angle (degrees) reached were calculated at the sphenoid face and sella. Data were analyzed using descriptive statistics and tests of statistical significance. The significance level was set at  ≤  0.05.  A significant improvement in both dimensions of working space was observed with each stage of dissection at the level of the sphenoid face. Maximal working space was achieved following bilateral middle turbinectomy and wide posterior septectomy with a 38 and 29% increase in working space in the mediolateral and craniocaudal dimensions, respectively. The largest stepwise increase in working space was observed with unilateral middle turbinectomy (mediolateral: 24 ± 3 mm and craniocaudal: 20 ± 3 mm). A trend toward improved degrees of visualization was observed with each stage of dissection but was not statistically significant.  Approaches to the skull base can be enhanced by selective unilateral/bilateral partial middle turbinectomy and posterior septectomy being performed to improve visualization and maximize surgical working freedom.
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http://dx.doi.org/10.1055/s-0038-1675591DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6748850PMC
October 2019

The image-guided operating room-Utility and impact on surgeon's performance in the head and neck surgery.

Head Neck 2019 09 9;41(9):3372-3382. Epub 2019 Jul 9.

Department of Otolaryngology-Head and Neck Surgery, University of Toronto, Toronto, Ontario, Canada.

Background: The image-guided operating room (OR) is an emerging standard for dealing with complex cases in many surgical disciplines including neurosurgery, thoracic surgery, maxillofacial trauma, and orthopedic surgery. Its use in head and neck oncological surgery is not well established. The primary aim of this study was to assess the image quality of cone-beam CT (CBCT) under real clinical conditions. The secondary aim was to assess the effect on surgical performance and decision making.

Methods: Intraoperative 3D imaging was performed using a CBCT capable C-Arm mounted on a multi-axis robot (Siemens Zeego) in the image-guided OR. All patients had immediate preoperative imaging taken with further intraoperative imaging performed as required. Ten initial patients, comprising 28 intraoperative scans, were used for questionnaire-based image reviews conducted with experienced head and neck clinicians. Scans were assessed for aspects of both image quality and clinical utility, on separate 5-point Likert scales (1-5).

Results: The median rating for bony detail was 4 out of 5. Vascular detail was increased (P < 10 ) from 1 to 3 with the use of IV contrast (region of interest CT# was 284 HU [SD, 47 HU]). Images were rated as 4 for freedom from artifact. Soft tissue definition was 2, with no significant improvement (P = .2) with the addition of IV iodinated contrast. Surgeons rated the greatest clinical utility (4) for the CBCT when assessing postreconstruction imaging of a complex case.

Conclusions: The image quality of CBCT in the image-guided OR is good for bony detail and complex oncological reconstructions in the head and neck setting but probably has limited benefit for intraoperative soft tissue delineation. Future studies must also focus on clinical outcomes to help demonstrate the value of the image-guided OR.
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http://dx.doi.org/10.1002/hed.25864DOI Listing
September 2019

Use of Porphysomes to detect primary tumour, lymph node metastases, intra-abdominal metastases and as a tool for image-guided lymphadenectomy: proof of concept in endometrial cancer.

Theranostics 2019 13;9(9):2727-2738. Epub 2019 Apr 13.

Institute of Medical Science, University of Toronto, Toronto, ON, Canada.

: To investigate Porphysome fluorescence image-guided resection (PYRO-FGR) for detection of uterine tumour, metastatic lymph nodes and abdominal metastases in a model of endometrial cancer. : White New Zealand rabbits were inoculated with VX2 cells via intra-myometrial injection. At 30 days, Porphysomes were administered intravenously. At 24 h the abdomen was imaged and fluorescent tissue identified (PYRO-FGR). After complete resection of fluorescent tissue, fluorescence-negative lymph nodes and peritoneal biopsies were removed. Histopathology including ultra-staging and analysis by a pathologist was used to detect tumour. Fluorescence signal to background ratio (SBR) was calculated and VX2 (+) tissue compared to VX2 (-) tissue. Biodistribution was calculated and Porphysome accumulation in fluorescent VX2 (+) tissue compared to fluorescent VX2 (-) and non-fluorescent VX2 (-) tissue. : Of 17 VX2 models, 10 received 4 mg/kg of Porphysomes and 7 received 1 mg/kg. Seventeen tumours (UT), 81 lymph nodes (LN) and 54 abdominal metastases (AM) were fluorescence-positive and resected. Of these, 17 UT, 60 LN and 45 AM were VX2 (+), while 16 LN and 5 AM were VX2 (-). Nine specimens were excluded from analysis. Thirty-one LN and 53 peritoneal biopsies were fluorescence-negative and resected. Of these, all LN and 51/53 biopsies were VX2 (-) with only 2 false-negative biopsies. Sensitivity and specificity of PYRO-FGR for VX2 (+) tissue was 98.4% / 80.0% overall, 100% / 100% for UT, 100% / 66.0 % for LN and 95.7% / 91.4% for AM. Increased SBR and biodistribution was observed in VX2 (+) tissue vs. VX2 (-) tissue. : Porphysomes are a highly sensitive imaging agent for intra-operative detection and resection of uterine tumour, metastatic lymph nodes and abdominal metastases.
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http://dx.doi.org/10.7150/thno.31225DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6525988PMC
June 2020

Intraoperative cone-beam CT-guided osteotomy navigation in mandible and maxilla surgery.

Laryngoscope 2020 05 21;130(5):1166-1172. Epub 2019 May 21.

Guided Therapeutics (GTx) Program, TECHNA Institute, University of Toronto, Princess Margaret Cancer Centre, Toronto, Ontario, Canada.

Objectives: Surgical navigation systems based on preoperative imaging are now increasingly used for guidance of head and neck resection and reconstruction. The primary aim of this study was to quantify osteotomy cutting accuracy using an image-guidance system for intraoperative cone-beam computed tomography (CBCT) imaging and surgical saw navigation. To enable clinical translation of this CBCT-guided navigation system, a secondary aim of the study was to design and fabricate a patient reference tracker suitable for clinical use on a mobile mandible.

Methods: First, a preclinical cadaveric study was performed to quantify navigation accuracy with the use of clinically suitable patient reference trackers. Second, a proof-of-principle patient study was conducted to evaluate this technique under clinical conditions.

Results: In both preclinical (5 cadavers) and clinical (5 patients) experiments, the mean cutting accuracy was less than 2 mm. In all preclinical specimens, bilateral mandibulectomies and bilateral maxillectomies were performed, for a total of 20 cut planes for analysis. The mean (standard deviation [SD]) values for distance, pitch, and roll were 1.4 mm (1.1 mm), 4.2° (3.5°), and 2.9° (2.5°) mm, respectively. Five mandibulectomies were performed on five patients, for a total of 10 cut planes for analysis. The mean (SD) values for distance, pitch, and roll were 1.7 mm (0.8 mm), 5.4° (1.5°), and 6.7° (4.6°) mm, respectively.

Conclusions: The overall performance in comparison to alternative approaches warrants further consideration. In terms of accuracy, the results presented here are comparable to recent systematic reviews assessing CAD-CAM cutting guides that cite accuracies of ~2 to 2.5 mm.

Level Of Evidence: 2 Laryngoscope, 130:1122-1127, 2020.
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http://dx.doi.org/10.1002/lary.28082DOI Listing
May 2020

Donor prone positioning protects lungs from injury during warm ischemia.

Am J Transplant 2019 10 25;19(10):2746-2755. Epub 2019 Apr 25.

Latner Thoracic Surgery Research Laboratories, Toronto General Hospital Research Institute, University Health Network, University of Toronto, Toronto, ON, Canada.

A large proportion of controlled donation after circulatory death (cDCD) donor lungs are declined because cardiac arrest does not occur within a suitable time after the withdrawal of life-sustaining therapy. Improved strategies to preserve lungs after asystole may allow the recovery team to arrive after death actually occurs and enable the recovery of lungs from more cDCD donors. The aim of this study was to determine the effect of donor positioning on the quality of lung preservation after cardiac arrest in a cDCD model. Cardiac arrest was induced by withdrawal of ventilation under anesthesia in pigs. After asystole, animals were divided into 2 groups based on body positioning (supine or prone). All animals were subjected to 3 hours of warm ischemia. After the observation period, donor lungs were explanted and preserved at 4°C for 6 hours, followed by 6 hours of physiologic and biological lung assessment under normothermic ex vivo lung perfusion. Donor lungs from the prone group displayed significantly greater quality as reflected by better function during ex vivo lung perfusion, less edema formation, less cell death, and decreased inflammation compared with the supine group. A simple maneuver of donor prone positioning after cardiac arrest significantly improves lung graft preservation and function.
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http://dx.doi.org/10.1111/ajt.15363DOI Listing
October 2019

3D Models in the Diagnosis of Subglottic Airway Stenosis.

Ann Thorac Surg 2019 06 27;107(6):1860-1865. Epub 2019 Feb 27.

Division of Thoracic Surgery, University of Toronto, Toronto, Ontario, Canada.

Purpose: Preoperative assessment of benign subglottic stenosis is usually performed by endoscopy and a computed tomography scan. Both diagnostic modalities have relevant limitations and sometimes an accurate assessment of the extent of disease is challenging.

Description: Based on computed tomography scans of benign glotto-subglottic stenosis and a control airway, color-coded three-dimensional (3D) models were produced using a commercially available 3D printer. The diagnostic relevance of 3D models was tested by means of a quiz.

Evaluation: 52 thoracic surgeons from 4 North American and 1 European institution with different levels of experience in airway surgery were invited to test the diagnostic accuracy of 3D models against endoscopy films and computed tomography scans. 3D models were found to be superior to the other two diagnostic tools in terms of grading the extent of the stenosis and selecting the correct surgical strategy. The group of residents benefited the most from the 3D models.

Conclusions: 3D models of complex glotto-subglottic airway stenosis are a useful supplement of the preoperative assessment. In addition, they can serve as a teaching tool for residents and fellows.
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http://dx.doi.org/10.1016/j.athoracsur.2019.01.045DOI Listing
June 2019

Evaluation of Novel Imaging Devices for Nanoparticle-Mediated Fluorescence-Guided Lung Tumor Therapy.

Ann Thorac Surg 2019 06 8;107(6):1613-1620. Epub 2019 Feb 8.

Division of Thoracic Surgery, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada. Electronic address:

Background: Nonsurgical and minimally invasive approaches for early-stage peripheral lung cancer are needed to avoid the known morbidity of surgical resection, particularly in high-risk patients. We previously demonstrated the utility of multifunctional porphyrin-phospholipid nanoparticles (porphysomes) for fluorescence imaging and phototherapy after preferential accumulation into tumors. The objective of this study was to demonstrate the feasibility of porphysome-mediated imaging and photothermal therapy using a newly developed fiberscope and thoracoscope.

Methods: To prepare this technology for clinical translation, we developed a porphysome-specific fiberscope (scanning fiber endoscope and porphysome-specific thoracoscope), both capable of detecting porphysome fluorescence, for image-guided transbronchial and transpleural photothermal therapy to treat endobronchial/peribronchial and subpleural tumors, respectively. These were tested in three animal models: human lung cancer xenografts (A549) in mice, orthotopic VX2 lung tumors in rabbits, and ex vivo pig lung into which A549 tumor tissue was transplanted.

Results: The scanning fiber endoscope, with a 1.2-mm diameter, is small enough to pass through the working channel of a conventional bronchoscope and could visualize porphysome-laden tumors located inside or close to the peripheral bronchial wall. The porphysome-specific thoracoscope system had high sensitivity for porphysome fluorescence and enabled image-guided thoracoscopic resection of porphysome-accumulating tumors close to the pleura. Porphysomes also enhanced the efficacy of scanning fiber endoscope-guided transbronchial photothermal therapy and porphysome-specific thoracoscope-guided transpleural photothermal therapy, resulting in selective and efficient tumor tissue ablation in the rabbit and pig models.

Conclusions: These results support the potential for clinical translation of this novel platform to affect nonsurgical and minimally invasive treatment options for early-stage peripheral lung cancer.
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http://dx.doi.org/10.1016/j.athoracsur.2019.01.008DOI Listing
June 2019

Analysis of simulated mandibular reconstruction using a segmental mirroring technique.

J Craniomaxillofac Surg 2019 Mar 30;47(3):468-472. Epub 2018 Dec 30.

Department of Otolaryngology, Head & Neck Surgery/Surgical Oncology, Princess Margaret Cancer Centre and Guided Therapeutics (GTx) Program, University of Toronto, Toronto, Ontario, Canada. Electronic address:

Purpose: When deforming pathology limits intraoperative plating of the mandible, three-dimensional (3D) models can be generated by digitally replacing the deformed segment of bone with an inverted segment from the contralateral unaffected mandible to adapt a reconstruction plate. The purpose of this study was to use 3D conformance analysis to evaluate the degree of accuracy of this "segmental mirroring" technique.

Methods: Using a pre-existing melanoma database (January 1, 2005-September 20, 2015), high-resolution computed tomography (CT) scans of the head and neck were obtained from patients without evidence of bony disease or defects involving the mandible. Using 3D software (Mimics, Materialise, Leuven, Belgium), each mandible was segmented based on four defect classes (Ic, II, IIc and III) of the Brown et al. (2016) classification system. An inverted, or "mirrored", image of each segment was digitally created and manually co-registered with the corresponding contralateral segment of the mandible. Conformance analysis was performed by calculating the root-mean-square (RMS) conformance distance and through evaluating 3D generated conformance maps. The primary outcome was degree of conformance. Data were analyzed using descriptive statistics and tests of statistical significance. The significance level was set at a p-value less than or equal to .05.

Results: A high degree of conformance (mean RMS < 1 mm) was observed when comparing all classes of simulated reconstruction. The closest conformance was observed for class III simulated reconstructions (mean RMS: 0.4 ± 0.2 mm). Inclusion of the condyle resulted in a reduced mean RMS conformance (class II: 0.5 ± 0.3 mm vs class IIc: 0.7 ± 0.5 mm; p = 0.01). There was no significant difference between RMS conformance distances when comparing side of simulated reconstruction. Evaluation of 3D mapping demonstrated reduced conformance with simulated reconstruction of the condyle and coronoid process.

Conclusion: The segmental mirroring technique can be used reliably to generate highly accurate three-dimensional models that may assist with mandibular reconstruction in circumstances where bony deformity limits intraoperative adaptation of a reconstruction plate. This technique is less accurate where pathology involves the mandibular condyle and, to a lesser degree, the coronoid process.
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http://dx.doi.org/10.1016/j.jcms.2018.12.016DOI Listing
March 2019

Nanoparticle-based CT visualization of pulmonary vasculature for minimally-invasive thoracic surgery planning.

PLoS One 2019 17;14(1):e0209501. Epub 2019 Jan 17.

Division of Thoracic Surgery, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada.

Purpose: To evaluate CF800, a novel lipid-based liposomal nanoparticle that co-encapsulates indocyanine green (ICG) and iohexol, for CT imaging of pulmonary vasculature in minimally-invasive thoracic surgery planning.

Methods: CF800 was intravenously administered to 7 healthy rabbits. In vivo CT imaging was performed 15 min post-injection, with a subset of animals imaged at 24h, 48h, and 72h post injection. Signal-to-background ratios (SBR) were calculated at the inferior vena cava and compared across time-points. A similar protocol was applied to 2 healthy pigs to evaluate the feasibility and efficacy in a large animal model. To evaluate the feasibility of clinical application, a survey was completed by 7 surgical trainees to assess pre- and post-injection CT images of rabbits and pigs. Responses on the discernibility of pulmonary vasculature sub-branches and comfort level to use the images for pre-operative planning were collected and analyzed.

Results: CF800 injection improved visualization of pulmonary vessels in both rabbit and pig models. The SBR of rabbit pulmonary vasculature was significantly higher after CF800 injection (range 3.7-4.4) compared to pre-injection (range 3.3-3.8, n = 7; p<0.05). SBR remained significantly different up to 24 hours after injection (range 3.7-4.3, n = 4; p<0.05). Trainees' evaluation found the post-injection CT images had significantly higher discernibility at the second vessel branch generation in both rabbit and pig models. Trainees identified smaller vasculature branch generations in the post-injection images compared to the pre-treatment images in both rabbit (mean 6.7±1.8 vs 5.4±2.1; p<0.05) and pig (mean 6.7±1.8 vs 5.4±2.1; p<0.05). Trainees were significantly more comfortable using post-injection images for surgical planning compared to the pre-injection images (rabbit: 8.1±1.1 vs. 4.7±2.1; pig: 7.6±2.1 vs. 4.9±2.2; p<0.05).

Conclusion: CF800 provides SBR and contrast enhancement of pulmonary vasculature which may assist in pre-surgical CT planning of minimally invasive thoracic surgery.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0209501PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6336249PMC
September 2019

Volumetric Analysis of Endoscopic and Maxillary Swing Surgical Approaches for Nasopharyngectomy.

J Neurol Surg B Skull Base 2018 Oct 19;79(5):466-474. Epub 2018 Jan 19.

TECHNA Institute, University Health Network, Toronto, Ontario, Canada.

 The endoscopic endonasal approach (EEA) for nasopharyngectomy is an alternative to the maxillary swing approach (MSA) for selected recurrent nasopharyngeal carcinomas (NPC). We compare the access between these approaches.  Three cadaver specimens were used to compare access volumes of the EEA and MSA. Exposure volumes were calculated using image guidance registration to cone beam computed tomography and tracking of accessible tissue with volumetric quantification. The area of exposure to the carotid artery was measured.  The MSA provided higher volumes for access volume compared with the EEA (66.6 vs 39.1 cm ,  = 0.009). The working area was larger in the MSA (80.2 vs 56.9 cm ,  = 0.06). The exposure to the carotid artery was higher in the MSA (1.88 vs 1.62 cm ,  = 0.04). The MSA provided larger volume of exposure for tumors of the parapharyngeal space with exposure below the palate.  This study suggests that the MSA for nasopharyngectomy provides a larger volume of exposure. However, much of the increased exposure relates to exposure of the parapharyngeal space below the palate. The EEA provides adequate access to superior anatomical structures.
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http://dx.doi.org/10.1055/s-0037-1617432DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6133661PMC
October 2018

Novel Thoracoscopic Navigation System With Augmented Real-Time Image Guidance for Chest Wall Tumors.

Ann Thorac Surg 2018 11 16;106(5):1468-1475. Epub 2018 Aug 16.

Division of Thoracic Surgery, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada; Princess Margaret Cancer Centre and Guided Therapeutics Program-TECHNA Institute, University Health Network, Toronto, Ontario, Canada. Electronic address:

Background: We developed a thoracoscopic surgical navigation system with real-time augmented image guidance to assess the potential benefits for minimally invasive resection of chest wall tumors. The accuracy of localization of tumor and resection margin and the effect on task workload and confidence were evaluated in a chest wall tumor phantom.

Methods: After scanning a realistic tumor phantom by cone-beam computed tomography and registering the data into the system, three-dimensional contoured tumor and resection margin was displayed. Fifteen surgeons were asked to localize the tumor margin and surgical margins with the thoracoscope alone. The same procedure was performed with the surgical navigation system activated, and results were compared between each attempt. A questionnaire and National Aeronautics and Space Administration Task Load Index were completed after.

Results: The surgical navigation system significantly reduced localization error for the medial (p = 0.002) and superior tumor margin (p < 0.001), which was difficult to visualize by thoracoscopy alone. All surgical resection margins were improved circumferentially, including margins that were readily visible by thoracoscopy. National Aeronautics and Space Administration Task Load Index response scores showed a statistically significant reduction in workload in all subscales. There was a more than 50% mean reduction in workload for performance (10.1 vs 4.4, p = 0.001) and frustration (13.0 vs 5.4, p = 0.001).

Conclusions: This study showed that the thoracoscopic surgical navigation system providing augmented image guidance decreased tumor localization error for regions difficult to visualize thoracoscopically and also reduced surgical margin error circumferentially, regardless of thoracoscopic visibility. This system also reduced workload and increased surgeon's confidence in localizing challenging chest wall tumors.
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http://dx.doi.org/10.1016/j.athoracsur.2018.06.062DOI Listing
November 2018

Cone-Beam Computed Tomography-Guided Navigation in Complex Osteotomies Improves Accuracy at All Competence Levels: A Study Assessing Accuracy and Reproducibility of Joint-Sparing Bone Cuts.

J Bone Joint Surg Am 2018 May;100(10):e67

Department of Surgical Oncology, University Health Network, Toronto, Ontario, Canada.

Background: The objective of this study was to assess the accuracy and reproducibility of a novel cone-beam computed tomography (CBCT)-guided navigation system designed for osteotomies with joint-sparing bone cuts.

Methods: Eighteen surgeons participated in this study. First, 3 expert tumor surgeons resected bone tumors in 3 Sawbones tumor models identical to actual patient scenarios. They first performed these osteotomies without navigation and then performed them using a navigation system and 3-dimensional (3D) planning tools based on CBCT imaging. The 2 sets of measurements were compared using image-based measurements from post-resection CBCT. Next, 15 residents, fellows, and orthopaedic staff surgeons were instructed on the use of the system, and their navigated resections were compared with navigated resections performed by the 3 expert tumor surgeons.

Results: One hundred and twenty-six navigated cuts done by the orthopaedic oncologists were compared with 126 non-navigated cuts by the same surgeons. The cuts violated the tumor in 22% (6) of the 27 non-navigated resections compared with none of the 27 navigated resections. The navigated cuts were significantly more accurate in terms of entry point, pitch, and roll (p < 0.001). The variation among the 3 surgeons when they used navigation was <0.6 mm for the entry cut and, on average, 1.5° for pitch and roll. All 18 surgeons then completed a total of 144 navigated cuts. The level of experience did not result in a significant difference among groups with regard to cut accuracy. Two cuts went into the tumor. The mean distance from the planned bone cuts to the actual entry points into bone was 1.5 mm (standard deviation [SD] = 1.4 mm) for all users. The mean difference in pitch and roll between the planned and actual cuts was 3.5° (SD = 2.8°) and 3.7° (SD = 3.2°) for all users.

Conclusions: Even in expert hands, navigated cuts were significantly more accurate than non-navigated cuts. When the osteotomies were aided by navigation, their accuracy did not differ according to the level of professional experience. CBCT-based metrics enable intraoperative assessments of cut accuracy and reconstruction planning.

Clinical Relevance: CBCT-guided navigated osteotomies can improve accuracy regardless of surgeon experience and decrease the variability among different surgeons.
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http://dx.doi.org/10.2106/JBJS.16.01304DOI Listing
May 2018
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