Patient-specific Anatomy Research Articles

Conformal Geometry and Multimaterial Additive Manufacturing through Freeform Transformation of Building Layers.

3D printing, formally known as additive manufacturing, creates complex geometries via layer-by-layer addition of materials. While 3D printing has been historically perceived as the static addition of build layers, 3D printing is now considered as a dynamic assembly process. In this context, here a new 3D printing process is reported that executes full degree-of-freedom (DOF) transformation (translating, rotating, and scaling) of each individual building layer while utilizing continuous fabrication techniques. Transforming individual building layers within the sequential layered manufacturing process enables dynamic transformation of the 3D printed parts on-the-fly, eliminating the time-consuming redesign steps. Preserving the locality of the transformation to each layer further enables the discrete conformal transformation, allowing objects such as vascular scaffolds to be optimally fabricated to properly fit within specific patient anatomy obtained from the magnetic resonance imaging (MRI) measurements. Finally, exploiting the freedom to control the orientation of each individual building layer, multimaterials, multiaxis 3D printing capability are further established for integrating functional modules made of dissimilar materials in 3D printed devices. This final capability is demonstrated through 3D printing a soft pneumatic gripper via heterogenous integration of rigid base and soft actuating limbs.

Immersive 3-Dimensional Virtual Reality Modeling for Case-Specific Presurgical Discussions in Cerebrovascular Neurosurgery.

Adequate surgical planning includes a precise understanding of patient-specific anatomy and is a necessity for neurosurgeons. Although the use of virtual reality (VR) technology is emerging in surgical planning and education, few studies have examined the effectiveness of immersive VR during surgical planning using a modern head-mounted display. To investigate if and how immersive VR aids presurgical discussions of cerebrovascular surgery. A multiuser immersive VR system, BananaVisionTM, was developed and used during presurgical discussions in a prospective patient cohort undergoing cerebrovascular surgery. A questionnaire/interview was administered to multiple surgeons after the surgeries to evaluate the effectiveness of the VR system compared to conventional imaging modalities. An objective assessment of the surgeon's knowledge of patient-specific anatomy was also conducted by rating surgeons' hand-drawn presurgical illustrations. The VR session effectively enhanced surgeons' understanding of patient-specific anatomy in the majority of cases (83.3%). An objective assessment of surgeons' presurgical illustrations was consistent with this result. The VR session also effectively improved the decision-making process regarding minor surgical techniques in 61.1% of cases and even aided surgeons in making critical surgical decisions about cases involving complex and challenging anatomy. The utility of the VR system was rated significantly higher by trainees than by experts. Although rated as more useful by trainees than by experts, immersive 3D VR modeling increased surgeons' understanding of patient-specific anatomy and improved surgical strategy in certain cases involving challenging anatomy.

Visualization of Human Spine Biomechanics for Spinal Surgery.

We propose a visualization application, designed for the exploration of human spine simulation data. Our goal is to support research in biomechanical spine simulation and advance efforts to implement simulation-backed analysis in surgical applications. Biomechanical simulation is a state-of-the-art technique for analyzing load distributions of spinal structures. Through the inclusion of patient-specific data, such simulations may facilitate personalized treatment and customized surgical interventions. Difficulties in spine modelling and simulation can be partly attributed to poor result representation, which may also be a hindrance when introducing such techniques into a clinical environment. Comparisons of measurements across multiple similar anatomical structures and the integration of temporal data make commonly available diagrams and charts insufficient for an intuitive and systematic display of results. Therefore, we facilitate methods such as multiple coordinated views, abstraction and focus and context to display simulation outcomes in a dedicated tool. By linking the result data with patient-specific anatomy, we make relevant parameters tangible for clinicians. Furthermore, we introduce new concepts to show the directions of impact force vectors, which were not accessible before. We integrated our toolset into a spine segmentation and simulation pipeline and evaluated our methods with both surgeons and biomechanical researchers. When comparing our methods against standard representations that are currently in use, we found increases in accuracy and speed in data exploration tasks. in a qualitative review, domain experts deemed the tool highly useful when dealing with simulation result data, which typically combines time-dependent patient movement and the resulting force distributions on spinal structures.

A Preliminary Investigation Into the Feasibility of Semi-Autonomous Surgical Path Planning for a Mastoidectomy Using LSTM-Recurrent Neural Networks

Abstract Path planning algorithms for robotics can be as simple as having an operator program waypoints into a robot's controller and having the robot perform a simple task such as welding. This works well in an industrial setting but will not work for complicated tasks such as performing surgery. Another approach would be to use a constraint function in programing a robot to perform surgery, but it would be difficult to capture and represent all of the surgeon's information in the mathematical terms required for a cost function. A third approach, and the one utilized in this study, is to train a set of artificial neural networks (ANNs) using recorded surgeons' motions when manipulating a surgical instrument during procedure training using a surgery simulator. This has the advantage of indirectly capturing the surgeon's abilities and intentions without needing to explicitly capture all of the motion information that must be encoded from their trajectory planning and decision-making, and then, say, creating a complex constraint function using that information. In this research effort, virtually captured surgical trajectories from trained surgeons were used to train ANNs, after being preprocessed into three subtasks. Each set of subtask data was used to train a separate ANN. Each of the ANNs was trained using a custom cost function and evaluated using custom metrics. During the training, the positions of fiducial markers, recorded during procedure attempts, were used to orient the recorded path relative to the patient's anatomy. Although the ANN-generated trajectories were not used to perform surgery on a live patient in this study, the fiducial marker position information is intended to be exploited during a real procedure to position, orient, and scale a tool trajectory to suit a patient's specific anatomy. The trained ANNs were subjected to several tests to assess their safety and robustness. We found that even when trained on a small number of datasets, the ANNs converged and could generate output trajectories that were still assessed to be safe even when slight changes in the fiducial marker placement locations were given.

Clinical Implementation of In-House Developed MR-Based Patient-Specific 3D Models of Liver Anatomy

Knowledge of patient-specific liver anatomy is key to patient safety during major hepatobiliary surgery. Three-dimensional (3D) models of patient-specific liver anatomy based on diagnostic MRI images can provide essential vascular and biliary anatomical insight during surgery. However, a method for generating these is not yet publicly available. This paper describes how these 3D models of the liver can be generated using open source software, and then subsequently integrated into a sterile surgical environment. The most common image quality aspects that degrade the quality of the 3D models as well possible ways of eliminating these are also discussed. Per patient, a single diagnostic multiphase MRI scan with hepatospecific contrast agent was used for automated segmentation of liver contour, arterial, portal, and venous anatomy, and the biliary tree. Subsequently, lesions were delineated manually. The resulting interactive 3D model could be accessed during surgery on a sterile covered tablet. Up to now, such models have been used in 335 surgical procedures. Their use simplified the surgical treatment of patients with a high number of liver metastases and contributed to the localization of vanished lesions in cases of a radiological complete response to neoadjuvant treatment. They facilitated perioperative verification of the relationship of tumors and the surrounding vascular and biliary anatomy, and eased decision-making before and during surgery.

Repair of sinus venosus defects with partial anomalous pulmonary venous connection in adult: Four surgical procedures for a large armamentarium

Surgical repair of sinus venosus defects with partial anomalous pulmonary venous connection (PAPVC) to the superior vena cava (SVC) has been associated with venous return obstructions, and sinus node dysfunction. We aimed to evaluate the safety of four different surgical procedures, for repair of sinus venosus defects with PAPVC, in 23 adult patients, adapted to each patient's specific anatomy assessed by 3D computed tomography. Between March 2010 and May 2019, we performed anatomic repair of sinus venosus defects with a single patch ( n = 6; 26.1%), 2-patch ( n = 9; 39.1%), Warden ( n = 3; 13%), or modified Warden procedure with reconstruction of the divided SVC using a PTFE conduit ( n = 5; 21.7%) ( Fig. 1 ). Median age was 40 years [range, 15 to 73 years]. Main associated procedures were: creation of atrial septal defect ( n = 1), tricuspid valvuloplasty ( n = 2), tricuspid valve replacement ( n = 1), pulmonary valve replacement ( n = 1), monoblock “cut and sew” of pulmonary veins and superior vena cava ( n = 1). Follow-up was 3.26 years [range, 2 months to 10 years]. There were no mortality and no obstruction of SVC and pulmonary veins at the time of discharge and during follow-up. Aortic clamping was shorter (60 ± 39 min) with the single patch technique and longer (112 ± 31 min) with the modified Warden procedure. Nineteen patients (82.6%) had regained sinus rhythm at discharge; a patient with paroxysmal atrial fibrillation had regained a sinus rhythm after the “cut and sew” isolation technique of the superior vena cava and pulmonary veins. All patients were NYHA 1. PAPVC can safely be performed with an appropriate technique, and low morbidity. The single patch technique, when anatomically possible, offers good results but now competes with transcatheter correction. When PAPVC is far from the SVC-right atrium junction, the modified Warden procedure offers an effective and obligatory surgical repair, without any increase in complications.

The Ross Procedure in Children: The Gold Standard?

The management of aortic valve disease in the pediatric population is complex and requires an individualized approach and opportune application of techniques focused on each individual patient's specific anatomy, pathology, and clinical presentation. Though some patients may require variations in the approach to management, the ultimate goal should be to perform a Ross procedure when aortic valve replacement is indicated.

In Reply: Mini-Pterional Craniotomy and Extradural Clinoidectomy for Clinoid Meningioma: Optimization of Exposure Using Augmented Reality Template: 2-Dimensional Operative Video.

A keyhole approach to a deep-lying skull base lesion, as such a clinoid meningioma, can be a daunting challenge.1-3 The minimally invasive exposure must be precisely placed and adequately wide to accomplish the surgical goal. Surgical rehearsal in virtual reality (VR) can not only increase the confidence of the surgeon through practice on patient-specific anatomy,4 but it can also generate navigation-integrated templates to ensure precise placement and adequate bone openings. In this operative video, we demonstrate the use of an augmented reality (AR) template in a 69-yr-old woman with a growing clinoid meningioma. The 3-dimensional, VR rendering (SNAP VR360, Surgical Theater Inc, Cleveland, Ohio) of her right clinoid meningioma was used in surgical rehearsal for the mini-pterional approach with extradural clinoidectomy. The optimal opening was saved as a VR file and, at surgery, projected into the eye-piece of the navigation-tracked microscope (Synchronized AR v3.8.0, Surgical Theater Inc). In this manner, the surgical opening in the template was visible in AR on the patient's anatomy in real time during surgery. The template enhanced the planning of the incision and soft-tissue exposure, guided the drilling of the sphenoid wing, facilitated the extradural clinoidectomy,5 and ultimately facilitated the accomplishment of the surgical goal of total resection of the meningioma. With this application of novel technology, the surgeon is no longer using navigation to get her/his bearings. Instead, the surgeon is using AR-enhanced navigation to duplicate a plan that is known to work. This is a fundamental paradigm shift. Patient consent was obtained prior to the creation of the video and is available on request.

Holographic Augmented Reality for DIEP Flap Harvest.

During a deep inferior epigastric perforator (DIEP) flap harvest, the identification and localization of the epigastric arteries and its perforators are crucial. Holographic augmented reality is an innovative technique that can be used to visualize this patient-specific anatomy extracted from a computed tomographic scan directly on the patient. This study describes an innovative workflow to achieve this. A software application for the Microsoft HoloLens was developed to visualize the anatomy as a hologram. By using abdominal nevi as natural landmarks, the anatomy hologram is registered to the patient. To ensure that the anatomy hologram remains correctly positioned when the patient or the user moves, real-time patient tracking is obtained with a quick response marker attached to the patient. Holographic augmented reality can be used to visualize the epigastric arteries and its perforators in preparation for a deep inferior epigastric perforator flap harvest. Potentially, this workflow can be used visualize the vessels intraoperatively. Furthermore, this workflow is intuitive to use and could be applied for other flaps or other types of surgery.

Cardiac CT perfusion and FFRCTA: pathophysiological features in ischemic heart disease.

Cardiac computed tomography (CCT) has rapidly evolved, becoming a powerful integrated tool for the evaluation of coronary artery disease (CAD), and being superior to other noninvasive methods due to its high accuracy and ability to simultaneously assess both lumen stenosis and atherosclerotic plaque burden. Furthermore, CCT is regarded as an effective gatekeeper for coronary angiography, and carries independent important prognostic information. In the last decade, the introduction of new functional CCT applications, namely CCT perfusion (CCTP) imaging and CT-derived fractional flow reserve (FFRCTA), has opened the door for accurate assessment of the haemodynamic significance of stenoses. These new CCT technologies, thus, share the unique advantage of assessing both myocardial ischemia and patient-specific coronary artery anatomy, providing an integrated anatomical/functional analysis. In the present review, starting from the pathophysiology of myocardial ischemia, we evaluate the existing evidence for functional CCT imaging and its value in relation to alternative, well-established, non-invasive imaging modalities and invasive indices of ischemia (currently the gold-standard). The knowledge of clinical applications, benefits, and limitations of these new CCT technologies will allow efficient and optimal use in clinical practice in the near future.

Deep learning prediction of proton and photon dose distributions for paediatric abdominal tumours

ObjectiveDose prediction using deep learning networks prior to radiotherapy might lead tomore efficient modality selections. The study goal was to predict proton and photon dose distributions based on the patient-specific anatomy and to assess their clinical usage for paediatric abdominal tumours. Material and methodsData from 80 patients with neuroblastoma or Wilms’ tumour was included. Pencil beam scanning (PBS) (5 mm/ 3%) and volumetric-modulated arc therapy (VMAT) plans (5 mm) were robustly optimized on the internal target volume (ITV). Separate 3-dimensional patch-based U-net networks were trained to predict PBS and VMAT dose distributions. Doses, planning-computed tomography images and relevant optimization masks (ITV, vertebra and organs-at-risk) of 60 patients were used for training with a 5-fold cross validation.The networks’ performance was evaluated by computing the relative error between planned and predicted dose-volume histogram (DVH) parameters for 20 inference patients. In addition, the organs-at-risk mean dose difference between modalities was calculated using planned and predicted dose distributions (ΔDmean = DVMAT-DPBS). Two radiation oncologists performed a blind PBS/VMAT modality selection based on either planned or predicted ΔDmean. ResultsAverage DVH differences between planned and predicted dose distributions were ≤ |6%| for both modalities. The networks classified the organs-at-risk Dmean difference as a gain (ΔDmean > 0) with 98% precision. An identical modality selection based on planned compared to predicted ΔDmean was made for 18/20 patients. ConclusionDeep learning networks for accurate prediction of proton and photon dose distributions for abdominal paediatric tumours were established. These networks allowing fast dose visualisation might aid in identifying the optimal radiotherapy technique when experience and/or resources are unavailable.

Fluid-Structure Interaction Simulation of an Intra-Atrial Fontan Connection.

Simple SummaryA fluid-structure interaction (FSI) simulation of an intra-atrial Fontan connection was performed. Power loss and pressure drop results fluctuated less during the FSI simulation than during the simulation run with rigid walls, but there were no observable differences in time-averaged pressure drop, connection power loss or hepatic flow distribution. These results suggested that employing a rigid wall is a reasonable assumption when evaluating time-averaged hemodynamic quantities of the Fontan connection under resting breath-held flow conditions.Total cavopulmonary connection (TCPC) hemodynamics has been hypothesized to be associated with long-term complications in single ventricle heart defect patients. Rigid wall assumption has been commonly used when evaluating TCPC hemodynamics using computational fluid dynamics (CFD) simulation. Previous study has evaluated impact of wall compliance on extra-cardiac TCPC hemodynamics using fluid-structure interaction (FSI) simulation. However, the impact of ignoring wall compliance on the presumably more compliant intra-atrial TCPC hemodynamics is not fully understood. To narrow this knowledge gap, this study aims to investigate impact of wall compliance on an intra-atrial TCPC hemodynamics. A patient-specific model of an intra-atrial TCPC is simulated with an FSI model. Patient-specific 3D TCPC anatomies were reconstructed from transverse cardiovascular magnetic resonance images. Patient-specific vessel flow rate from phase-contrast magnetic resonance imaging (MRI) at the Fontan pathway and the superior vena cava under resting condition were prescribed at the inlets. From the FSI simulation, the degree of wall deformation was compared with in vivo wall deformation from phase-contrast MRI data as validation of the FSI model. Then, TCPC flow structure, power loss and hepatic flow distribution (HFD) were compared between rigid wall and FSI simulation. There were differences in instantaneous pressure drop, power loss and HFD between rigid wall and FSI simulations, but no difference in the time-averaged quantities. The findings of this study support the use of a rigid wall assumption on evaluation of time-averaged intra-atrial TCPC hemodynamic metric under resting breath-held condition.

MRI-Based 3-Dimensional Visualization Workflow for the Preoperative Planning of Nephron-Sparing Surgery in Wilms’ Tumor Surgery: A Pilot Study

Purpose. Due to the size and localization of Wilms’ tumor (WT), nephron-sparing surgery (NSS) is only possible in a limited number of cases. When NSS is considered, the surgeon preoperatively requires a thorough understanding of the patient-specific anatomy to prevent positive surgical margins and other complications. Through a collaboration between the radiology and pediatric surgery departments and 3D imaging specialists, a 3D visualization workflow was developed to improve preoperative planning of NSS for WT patients. Methods. The 3D visualization workflow combines a MRA sequence, a segmentation protocol, and augmented reality (AR) visualization, additional to in-house 3D printing. A noncontrast-enhanced MRA scan was added to the MRI protocol. MRI sequences were segmented with a segmentation protocol in an open-source software package. The resulting 3D models were visualized in AR with a HoloLens and 3D print. Results. In a pilot study, five WT patients eligible for NSS were preoperatively planned through the 3D visualization workflow. AR visualization software was fast and free to use and allowed adequate handling of the 3D holograms. The 3D printed models were considered convenient and practical for intraoperative orientation. The patient-friendly, fast, and low-cost 3D visualization workflow was easily implemented and appeared to be valuable for the preparation of NSS. Conclusion. This pilot study demonstrates how a strong collaboration between the pediatric surgery and radiology departments and 3D imaging specialists will help to shape the future of pediatric oncological surgery. This 3D visualization workflow aims to prepare pediatric oncological surgeons for nephron-sparing surgery in patients with Wilms’ tumors.

Mini-Pterional Craniotomy and Extradural Clinoidectomy for Clinoid Meningioma: Optimization of Exposure Using Augmented Reality Template: 2-Dimensional Operative Video.

A "keyhole" approach to a deep-lying skull base lesion, as such a clinoid meningioma, can be a daunting challenge.1-3 The minimally invasive exposure must be precisely placed and adequately wide to accomplish the surgical goal. Surgical rehearsal in virtual reality (VR) can not only increase the confidence of the surgeon through practice on patient-specific anatomy,4 but it can also generate navigation-integrated templates to ensure precise placement and adequate bone openings. In this operative video, we demonstrate the use of an augmented reality (AR) template in a 69-yr-old woman with a growing clinoid meningioma. The 3-dimensional, VR rendering (SNAP VR360, Surgical Theater Inc, Cleveland, Ohio) of her right clinoid meningioma was used in surgical rehearsal for the mini-pterional approach with extradural clinoidectomy. The optimal opening was saved as a VR file and, at surgery, projected into the eye-piece of the navigation-tracked microscope (Synchronized AR v3.8.0, Surgical Theater Inc). In this manner, the surgical opening in the template was visible in AR on the patient's anatomy in real time during surgery. The template enhanced the planning of the incision and soft-tissue exposure, guided the drilling of the sphenoid wing, facilitated the extradural clinoidectomy,5 and ultimately facilitated the accomplishment of the surgical goal of total resection of the meningioma. With this application of novel technology, the surgeon is no longer using navigation to get her/his bearings. Instead, the surgeon is using AR-enhanced navigation to duplicate a plan that is known to work. This is a fundamental paradigm shift. Patient consent was obtained prior to the creation of the video and is available on request.

Accuracy evaluation of patient-specific 3D-printed aortic anatomy

Introduction3D printing has a wide range of applications in medicine. In surgery, this technique can be used for preoperative planning of complex procedures, production of patient specific implants, as well as training. However, accuracy evaluations of 3D vascular models are rare. ObjectivesAim of this study was to investigate the accuracy of patient-specific 3D-printed aortic anatomies. MethodsPatients suffering from aorto-iliac aneurysms and with indication for treatment were selected on the basis of different anatomy and localization of the aneurysm in the period from January 1st 2014 to May 27th 2016. Six patients with aorto-iliac aneurysms were selected out of the database for 3D-printing. Subsequently, computed tomography (CT) images of the printed 3D-models were compared with the original CT data sets. ResultsThe mean deviation of the six 3D-vascular models ranged between −0.73 mm and 0.14 mm compared to the original CT-data. The relative deviation of the measured values showed no significant difference between the 3D-vascular and the original patient CT-data. ConclusionOur results showed that 3D printing has the potential to produce patient-specific 3D vascular models with reliable accuracy. This enables the use of such models for the development of new endovascular procedures and devices.

An update on the improvement of patient eligibility with the use of new generation endografts for the treatment of abdominal aortic aneurysms

ABSTRACT Purpose Endovascular aneurysm repair (EVAR), performed within device instructions for use (IFU), offers improved outcomes. New endograft designs attempt to increase eligibility rates of abdominal aortic aneurysm (AAA) patients treated within device IFU. We aim to examine the anatomic suitability of the Ovation endograft in our AAA patients and compare it with the other contemporary devices. Research design and methods Three-hundred and seven consecutive elective AAA patients treated during a 5-year period were included. Patient-specific anatomic characteristics were based on endograft IFUs to determine eligibility rates of each system. Results Two-hundred-twenty-five patients underwent EVAR and 82 open surgery. Ineligibility for device implantation was significantly lower for the Ovation iX system (32%) compared to other devices (AFX-2:49%, Altura:49%, Anaconda:54%, Endurant II:46%, Excluder:52%, Excluder Conformable:39%, Incraft:43%, E-Tegra:52%, Zenith-Alpha:52%; P-Value<0.001). The Alto system (next-generation Ovation) achieved an even lower ineligibility rate of 30% (P = 0.008). Short proximal aortic neck length followed by access vessel inadequacy were the primary reasons for ineligibility. Conclusion The Ovation-iX included more patients with anatomic characteristics within device IFUs resulting in improved eligibility rates compared with the rest of contemporary devices. Its evolution, the Alto system, further improves patient eligibility due to the inclusion of shorter aortic necks. Expert Opinion The Ovation iX system presented a significantly better performance and was eligible for use in a greater number of patients in our series of elective AAA repairs, accommodating patient-specific aortic anatomies. Of course, performing EVAR within the endograft’s IFU is important to achieve optimal and durable outcomes. The proximal neck length followed by the size of the access vessels are the two more common factors resulting in loss of eligibility. Except for overall eligibility rates, a case by case decision must be made on which is the most suitable device for each patient, based on the specific characteristics of its unique anatomy.

A Novel Prostate SBRT vs HDR Comparison: A Disease Perspective

To compare current SBRT and HDR prostate treatment regimens from a disease perspective using the latest published dose-response functions We developed and validated a comprehensive software platform enabling in-silico growth of realistic prostate tumor-like volumes of random shape and morphology within prostate. Published probabilities of disease occurrence in various prostate zonal anatomies, for various disease stages were taken into account when tumorlets were generated. The model used the patient-specific segmented anatomy and dose distributions delivered for 10 patients. 4500 tumorlets, ranging from 0.1 to 10 cm3 were generated. Each tumorlet was overlapped with the dose distribution and the corresponding radiobiological integral parameters (EUBED, gBEUD) were computed. Data from 25 international radiotherapy outcome datasets, stratified by risk and use of ADT, were used to generate dose-response curves, fractionation sensitivity and repopulation. These values then enabled our model to convert integral metrics parameters into a probability of cure (PoC). A large range of radiobiological parameters, α/b = [1.5, 7.7] Gy and α = [0.04, 0.3] Gy-1 were explored in comparing currently accepted regimens (e.g. 7.25Gy x 5 and 13.5Gy x 2). SBRT plans were created using both RTOG 0938 and NRG GU005 criteria. A version of the plan was escalated from 36.25 to 40Gy. The two methods of integrating radio-biological dose effect (EUBED and gBEUD) handle dose inhomogeneity differently. SBRT plans display less dose inhomogeneity and consequently both formalisms produce very similar results. For HDR plans, which have more dose heterogeneity, the two formalisms produce slightly different results but for both, the PoC tends to decrease with the increased disease volume. Similar SBRT and HDR outcomes were observed for a very low α/b (1.5) and only low and intermediate risk disease. For higher α/b values, for all the dose-response curves examined, predictions showed that HDR provided a 5-30% increase in PoC, increasing with increased α/b and risk strata. The NRG plans, requiring higher dose coverage (98% vs 95%), produce, for the same prescription dose, a 1-5% PoC increase. The NRG 40Gy plans restore some of the PoC, when compared to HDR, particularly at large tumor volumes. We are presenting a novel perspective in comparing two treatment modalities or regimens. Our results show that using prescription dose alone in a BED-style equivalence, particularly when accounting for large degrees of variability in planning styles and delivery, has a limited value. The method we are proposing, looking at probabilities of cure at disease level –tumorlets- rather than physical peripheral prescription dose at gland level, has the potential to create a true equivalence between established and time-tested treatments (HDR) and newer modalities (SBRT), while accounting for all existent planning style variability.

PATIENT-SPECIFIC 3-D LUNG MODELING: THE FUTURE OF PRECISION LUNG CANCER SURGERY?

SESSION TITLE: Fellows Lung Cancer Posters SESSION TYPE: Fellow Case Report Posters PRESENTED ON: October 18-21, 2020 INTRODUCTION: Reconstruction software based on mathematical algorithms and machine learning are beginning to allow the processing of chest CT scans to generate highly specific 3D lung models. We describe our initial experience using this technology for simulation and planning of lung cancer resection. CASE PRESENTATION: DICOM data from patient CT scans was processed (IQQA-Lung, EDDA Technology, Princeton, NJ, USA) to generate 3D maps of patient's airways and vasculature as well as obtain information on lung volumes (cm3), tumor volume and volumes of individual lung lobes. Case 1: The model [Figure 1(A-G), Gif 1] generated demonstrated a 2.2 cm x 2.2 cm x 1.7 cm lesion in the left upper lobe (LUL). The lesion had a total volume of 3.39 cm3. Total lung volume (TLV), right lung volume (RLV) and left lung volume (LLV) were 4029.54 cm3, 2369.08 (58.79%) cm3 and 1660.46 (41.21%) cm3 respectively. LUL and left lower lobe (LLL) had volumes of 951.02 cm3 (57.27%) and 709.45 cm3 (42.73%) respectively. While the lesion appeared to be located in the lingular segment, our model showed that it crossed into the adjacent segments and a segmentectomy would have led to a close or positive margin. This was confirmed in the operating room. Case 2: The model [Figure 1(H-N), Gif 2] generated demonstrated a 2.6 cm x 2.3 cm x 1.3 cm lesion in the right lower lobe (RLL). The lesion had a total volume of 4.72 cm3. TLV, RLV and LLV were 2948.46 cm3, 1579.84 (53.58%) and 1368.62 (46.42%) cm3 respectively. Right upper lobe (RUL), right middle lobe (RML) and RLL had volumes of 738.09 cm3 (46.72%), 178.57 cm3 (11.3%) and 663.18 cm3 (41.98%) respectively. While the lesion appeared to be located in the superior segment, interplanar analysis showed that a segmentectomy would have led to a close or positive margin. This was confirmed intraoperatively. In addition, a small proximal pulmonary artery was identified preoperatively that informed on the need for extra vigilance during dissection of the PA. DISCUSSION: Highly accurate patient-specific lung models provide extensive detail on pulmonary vasculature and intersegmental planes, allowing for preoperative recognition of anatomic variations and guiding the extent of an ideal oncologic resection. The ability to get high-resolution images without the need for IV contrast is an added benefit. These models also provide an accurate measurement of postoperative residual lung volumes hence providing a surrogate marker for postoperative residual lung function and quality of life. These models also carry teaching value for residents and medical students. CONCLUSIONS: Highly accurate 3D lung models give detailed information on patient-specific anatomy as well as preoperative and postoperative lung volumes. These platforms should be utilized to obtain a better understanding of patient anatomy in order to make lung operations safer, more efficient and allow appropriate lung conservation surgery. Reference #1: Nakada, T., Akiba, T., Inagaki, T. and Morikawa, T., 2014. Thoracoscopic anatomical subsegmentectomy of the right S2b + S3 using a 3D printing model with rapid prototyping. Interact Cardiovasc Thorac Surg, 19(4), pp.696-698. Reference #2: Akiba T, Nakada T, Inagaki T. Three-Dimensional Pulmonary Model Using Rapid-Prototyping in Patient with Lung Cancer Requiring Segmentectomy. Annals of Thoracic and Cardiovascular Surgery. 2014;20(Supplement):490-492. DISCLOSURES: No relevant relationships by Mirza Zain Baig, source=Web Response No relevant relationships by Faiz Bhora, source=Web Response No relevant relationships by Zaid Muslim, source=Web Response

Cone Beam Computed Tomography Imaging in Dental Implants: A Primer for Clinical Radiologists.

With the introduction of cone beam computed tomography (CBCT) into dentistry in the 1990s, radiologists have become more frequently involved in dental implant planning. This article describes the information that should be included in a radiology report to achieve a successful implantation. The justification to use CBCT during the preoperative planning phase is based on the need to evaluate patient-specific anatomy in detail (general condition of the jaw, bone quantity, and bone quality), the application of more advanced surgical techniques (maxillary sinus augmentation procedure, zygomatic implants), and the integrated presurgical planning and virtual patient approach. Postoperatively, CBCT is used when implant retrieval is anticipated and two-dimensional radiographs have not provided sufficient information, for evaluation of graft healing, or to assess complications, mostly related to neurovascular trauma.

Surgical Guidance for Removal of Cholesteatoma Using a Multispectral 3D-Endoscope.

We develop a stereo-multispectral endoscopic prototype in which a filter-wheel is used for surgical guidance to remove cholesteatoma tissue in the middle ear. Cholesteatoma is a destructive proliferating tissue. The only treatment for this disease is surgery. Removal is a very demanding task, even for experienced surgeons. It is very difficult to distinguish between bone and cholesteatoma. In addition, it can even reoccur if not all tissue particles of the cholesteatoma are removed, which leads to undesirable follow-up operations. Therefore, we propose an image-based method that combines multispectral tissue classification and 3D reconstruction to identify all parts of the removed tissue and determine their metric dimensions intraoperatively. The designed multispectral filter-wheel 3D-endoscope prototype can switch between narrow-band spectral and broad-band white illumination, which is technically evaluated in terms of optical system properties. Further, it is tested and evaluated on three patients. The wavelengths 400 nm and 420 nm are identified as most suitable for the differentiation task. The stereoscopic image acquisition allows accurate 3D surface reconstruction of the enhanced image information. The first results are promising, as the cholesteatoma can be easily highlighted, correctly identified, and visualized as a true-to-scale 3D model showing the patient-specific anatomy.