Presurgical Planning Research Articles

Is Caton–Deschamps Index Reliable and Reproducible in Preoperative Assessment of Patellar Height for Patellar Instability Surgery?

The patellar height measurement is fundamental for surgical planning in patellar instability. The Caton–Deschamps index (CDI) is a widely employed method, but a gold standard is still lacking. The aim of this study was to evaluate the reliability and reproducibility of the CDI in a patellar height assessment and to hypothesize its employment in the preoperative planning of patellar stabilization surgery. A total of 29 cases of recurrent patellar instability undergoing surgical treatment were analyzed. The preoperative and postoperative CDI were measured by six different raters (three seniors and three juniors). The interclass correlation coefficient (ICC) of the six raters was calculated to evaluate the interobserver agreement. The seniors’ and juniors’ measurements were compared to assess the CDI reproducibility. The Fleiss kappa was calculated among the six raters to estimate the agreement in favor of an anterior tibial apophysis (ATA) transposition surgery. This study shows excellent absolute agreement in terms of the ICC for the raters’ average and for single raters as units, both preoperatively (p < 0.001) and postoperatively (p < 0.001). The agreement of the surgical choice between the six observers corresponds to “substantial agreement”. This study demonstrates that the CDI is reliable and reproducible, and it could represent a valuable tool in the clinical assessment, treatment choice and pre-surgical planning of patellar instability surgery.

Pancreaticoduodenal Groove: Spectrum of Disease and Imaging Features.

The pancreaticoduodenal groove (PDG) is a small space between the pancreatic head and duodenum where vital interactions between multiple organs and physiologic processes take place. Muscles, nerves, and hormones perform a coordinated dance, allowing bile and pancreatic enzymes to aid in digestion and absorption of critical nutrition. Given the multitude of organs and cells working together, a variety of benign and malignant entities can arise in or adjacent to this space. Management of lesions in this region is also complex and can involve observation, endoscopic resection, or challenging surgeries such as the Whipple procedure. The radiologist plays an important role in evaluation of abnormalities involving the PDG. While CT is usually the first-line examination for evaluation of this complex region, MRI offers complementary information. Although features of abnormalities involving the PDG can often overlap, understanding the characteristic imaging and pathologic features generally allows categorization of disease entities based on the suspected organ of origin and the presence of ancillary features. The goal of the authors is to provide radiologists with a conceptual approach to entities implicating the PDG to increase the accuracy of diagnosis and assist in appropriate management or presurgical planning. They briefly discuss the anatomy of the PDG, followed by a more in-depth presentation of the features of disease categories. A table summarizing the entities that occur in this region by underlying cause and anatomic location is provided. ©RSNA, 2022.

The Utilization of Diffusion Tensor Imaging as an Image-Guided Tool in Brain Tumor Resection Surgery: A Systematic Review.

Simple SummaryDiffusion tensor imaging (DTI) is an image-guided tool, especially in brain tumor resection surgery. Neuroimaging tools are essential for operative planning, particularly for maximizing tumor resection and, at the same time, preserving brain function. In this systematic review, we discuss the utilization of DTI in brain tumor resection, by looking into its ability to assess the perioperative approach, as well as evaluating its benefits for successful surgery. The present study proposes to use DTI as a vital neuroimaging tool for preoperative planning in brain tumor resection surgery.The diffusion tensor imaging technique has been recognized as a neuroimaging tool for in vivo visualization of white matter tracts. However, DTI is not a routine procedure for preoperative planning for brain tumor resection. Our study aimed to systematically evaluate the effectiveness of DTI and the outcomes of surgery. The electronic databases, PubMed/MEDLINE and Scopus, were searched for relevant studies. Studies were systematically reviewed based on the application of DTI in pre-surgical planning, modification of operative planning, re-evaluation of preoperative DTI data intraoperatively, and the outcome of surgery decisions. Seventeen studies were selected based on the inclusion and exclusion criteria. Most studies agreed that preoperative planning using DTI improves postoperative neuro-deficits, giving a greater resection yield and shortening the surgery time. The results also indicate that the re-evaluation of preoperative DTI intraoperatively assists in a better visualization of white matter tract shifts. Seven studies also suggested that DTI modified the surgical decision of the initial surgical approach and the rate of the GTR in tumor resection surgery. The utilization of DTI may give essential information on white matter tract pathways, for a better surgical approach, and eventually reduce the risk of neurologic deficits after surgery.

Integrating Network Neuroscience Into Epilepsy Care: Progress, Barriers, and Next Steps.

Drug resistant epilepsy is a disorder involving widespread brain network alterations. Recently, many groups have reported neuroimaging and electrophysiology network analysis techniques to aid medical management, support presurgical planning, and understand postsurgical seizure persistence. While these approaches may supplement standard tests to improve care, they are not yet used clinically or influencing medical or surgical decisions. When will this change? Which approaches have shown the most promise? What are the barriers to translating them into clinical use? How do we facilitate this transition? In this review, we will discuss progress, barriers, and next steps regarding the integration of brain network analysis into the medical and presurgical pipeline.

Presurgical Planning of 3D Printing for a Large Abdominal Pheochromocytoma and Paraganglioma

ObjectiveTo determine the significance of presurgical planning of three-dimensional (3D) printing for resection of a large abdominal pheochromocytoma (PCC) and paraganglioma (PGL). Patients and MethodsThirty patients were enrolled in the present study. Groups A and B included 15 patients each. Twenty-one patients were diagnosed with a PCC and 9 had a PGL. Twenty-five patients had hypertension; the other 5 patients were shown to have PCCs/PGLs during routine physical examination. Tumors with a maximum diameter > 10 cm were defined as large tumors and included in our study. All patients underwent open surgical procedures. The surgeries in Group A were performed with 3D printing and reconstruction, while the surgeries in Group B were performed without “3D help.” Online virtual and printed 3D models were available preoperatively. ResultsThe operative time was much shorter in Group A than Group B (152.6 ± 20.1 vs 214.9 ± 29.7 min, P < .001). Greater blood loss was recorded in Group B than Group A (459.6 ± 98.9 vs 196.7 ± 68.8 mL, P < .001). No severe complications (Clavien-Dindo Ⅲ-Ⅴ) occurred in either group. Pneumonia and lower extremity thrombosis were diagnosed in 2 Group A patients. Slow surgical wound healing and blood transfusion were recorded in 4 Group B patients. ConclusionPreoperative stereographic 3D printing models were of great value when planning resection of a large PCC/PGL. Specifically, 3D printing models were shown to reduce the operative time and blood loss.

Evaluation of cardiovascular morphology and associated anomalies in patients with crossed pulmonary arteries on multidetector computed tomography angiography.

The present study sought to study morphology and associated cardiovascular anomalies in patients with crossed pulmonary arteries on multidetector computed tomography (CT) angiography. We retrospectively evaluated all CT angiography studies performed at a tertiary medical center from January2014 to December2021 to identify patients with crossed pulmonary arteries. The associated cardiovascular anomalies as identified on CT angiography were evaluated. Out of 4773 patients who had undergone CT angiography for evaluation of congenital heart diseases, we identified 24 (0.5%) patients (18 males; mean age: 7.7 years) with crossed pulmonary arteries. Tetralogy of Fallot was associated in seven (29.17%) patients, double outlet right ventricle in one (4.17%) patient, and common arterial trunk in four (16.67%) patients. An aortopulmonary window was seen in three (12.5%) patients while atrial septal defect and ventricular septal defect were seen in two (8.33%) and 16 (66.67%) patients, respectively. Aortic arch anomalies were present in 16 (66.67%) patients including interrupted aortic arch and coarctation of aorta with hypoplastic aortic arch seen in two (8.33%) patients each. A double aortic arch with an atretic left arch was seen in one (4.17%) patient. Coronary artery anomalies were seen in three (12.5%) patients. Crossed pulmonary arteries are a rare anomaly and their presence suggests the coexistence of a variety of cardiovascular anomalies, including aortic arch anomalies and outflow tract malformations. Comprehensive CT angiography-based evaluation of cardiovascular morphology is imperative in the presence of crossed pulmonary arteries to facilitate presurgical planning.

Use of probabilistic tractography to provide reliable distinction of the motor and sensory thalamus for prospective targeting during asleep deep brain stimulation.

Accurate electrode placement is key to effective deep brain stimulation (DBS). The ventral intermediate nucleus (VIM) of the thalamus is an established surgical target for the treatment of essential tremor (ET). Retrospective tractography-based analysis of electrode placement has associated successful outcomes with modulation of motor input to VIM, but no study has yet evaluated the feasibility and efficacy of prospective presurgical tractography-based targeting alone. Therefore, the authors sought to demonstrate the safety and efficacy of probabilistic tractography-based VIM targeting in ET patients and to perform a systematic comparison of probabilistic and deterministic tractography. Fourteen patients with ET underwent preoperative diffusion imaging. Probabilistic tractography was applied for preoperative targeting, and deterministic tractography was performed as a comparison between methods. Tractography was performed using the motor and sensory areas as initiation seeds, the ipsilateral thalamus as an inclusion mask, and the contralateral dentate nucleus as a termination mask. Tract-density maps consisted of voxels with 10% or less of the maximum intensity and were superimposed onto anatomical images for presurgical planning. Target planning was based on probabilistic tract-density images and indirect target coordinates. Patients underwent robotic image-guided, image-verified implantation of directional DBS systems. Postoperative tremor scores with and without DBS were recorded. The center of gravity and Dice similarity coefficients were calculated and compared between tracking methods. Prospective probabilistic targeting of VIM was successful in all 14 patients. All patients experienced significant tremor reduction. Formal postoperative tremor scores were available for 9 patients, who demonstrated a mean 68.0% tremor reduction. Large differences between tracking methods were observed across patients. Probabilistic tractography-identified VIM fibers were more anterior, lateral, and superior than deterministic tractography-identified fibers, whereas probabilistic tractography-identified ventralis caudalis fibers were more posterior, lateral, and superior than deterministic tractography-identified fibers. Deterministic methods were unable to clearly distinguish between motor and sensory fibers in the majority of patients, but probabilistic methods produced distinct separation. Probabilistic tractography-based VIM targeting is safe and effective for the treatment of ET. Probabilistic tractography is more precise than deterministic tractography for the delineation of VIM and the ventralis caudalis nucleus of the thalamus. Deterministic algorithms tended to underestimate separation between motor and sensory fibers, which may have been due to its limitations with crossing fibers. Larger studies across multiple centers are necessary to further validate this method.

Experimental Investigation of Blood Mimicking Fluid Viscosity for Application in 3D-Printed Medical Simulator

Blood mimicking fluid (BMF) is blood that accurately mimics human blood. BMF is commonly used in 3D printed medical simulators for pre-surgical planning and simulation or intraoperative orientation to assist surgeons on cardiac surgical procedures. This research aims to develop a newly formulated BMF containing polysaccharide particles via varying the percent composition of xanthan gum-starch-water-glycerol-contrast agent mixture. The viscosity of the formulated BMF is compared with human blood and observed. A total of 10 BMF samples consisting of different components and composition ratios is prepared and the viscosity of each sample is measured at shear rates ranging from 0s−1 to 1000s−1. The results are tabulated and compared with human blood. Based on the results of the experiments conducted, the addition of polysaccharide particles was found to affect the viscosity of the BMF. The BMF sample with a composition of water 59.98 vol%, glycerol 40 vol%, 0.01 wt% xanthan gum and 0.01 wt% starch shows the smallest viscosity percentage difference when compared to the viscosity of actual blood. Viscosity plateau values was found at 3.71± 0.34 mPa.s which is within the range of actual normal human whole blood viscosity.

Image Registration-Based Method for Reconstructing Transcatheter Heart Valve Geometry from Patient-Specific CT Scans.

Accurate reconstruction of transcatheter aortic valve (TAV) geometries and other stented cardiac devices from computed tomography (CT) images is challenging, mainly associated with blooming artifacts caused by the metallic stents. In addition, bioprosthetic leaflets of TAVs are difficult to segment due to the low signal strengths of the tissues. This paper describes a method that exploits the known device geometry and uses an image registration-based reconstruction method to accurately recover the in vivo stent and leaflet geometries from patient-specific CT images. Error analyses have shown that the geometric error of the stent reconstruction is around 0.1mm, lower than 1/3 of the stent width or most of the CT scan resolutions. Moreover, the method only requires a few human inputs and is robust to input biases. The geometry and the residual stress of the leaflets can be subsequently computed using finite element analysis (FEA) with displacement boundary conditions derived from the registration. Finally, the stress distribution in self-expandable stents can be reasonably estimated by an FEA-based simulation. This method can be used in pre-surgical planning for TAV-in-TAV procedures or for in vivo assessment of surgical outcomes from post-procedural CT scans. It can also be used to reconstruct other medical devices such as coronary stents.

Imaging characteristics and associations of left atrioventricular valve atresia and patent aortic root with isometric atrial appendages on multidetector CT.

The present study sought to study the imaging associations of left atrioventricular valve (mitral) atresia and patent aortic root in patients with isomerism of atrial appendages as detected on multidetector computed tomography (CT) angiography MATERIALS AND METHODS: The CT angiography studies performed at a tertiary medical center from January 2014 to December 2021 were retrospectively evaluated to identify patients with left atrioventricular valve atresia and patent aortic root with isometric atrial chambers. The morphology of the atrial appendage and extent of pectinate muscles was used to identify the type of isomeric atrial chambers. A comprehensive assessment of discordant arrangement of organs and the variations in venoatrial connections was done. Left atrioventricular valve atresia in the presence of patent aortic root and isomeric atrial appendages was identified in eight patients (four males). The mean age at diagnosis was 7 years. Right isomerism of the atrial appendages was seen in five patients while three patients had left isomerism. Disharmonious patterns of abdominal visceral arrangement were seen in two patients. Atrial and ventricular septal defects were seen in all patients. The most common pattern of ventricular arterial connection was DORV (double outlet right ventricle) (n = 4). While fivepatients had normally related great arteries, three had aorta anterior to the pulmonary trunk. Right ventricular outflow obstruction was seen in seven patients. Right aortic arch with mirror image branching was seen in four patients. Coronary artery anomalies were seen in four patients. The presence of left atrioventricular valve atresia and patent aortic root with isomeric atrial appendages is a rare congenital anomaly frequently associated with anomalous systemic and pulmonary drainage, conotruncal anomalies, and right ventricular outflow obstruction. Hence, comprehensive CT-based evaluation is indispensable in providing detailed anatomy and aids in presurgical planning.

Anthropometric aspects used to treat fractures of the naso-orbito-ethmoido-maxillary (NOEM) complex in cases of facial trauma

Abstract BACKGROUND. Fractures of the naso-orbito-ethmoido-maxillary (NOEM) complex are frequently acquired post-traumatic lesions, with both aesthetic and functional consequences, if the diagnosis is not promptly established and the surgical correction is delayed. OBJECTIVES. This study was conducted in order to facilitate the diagnosis of NOEM complex fractures by using anthropometric measures. The aim was to obtain normal mean values of the evaluated parameters from a lot of healthy volunteers. MATERIAL AND METHODS. The measurements were conducted on patient-specific three-dimensional models obtained from processing the CT scan images and building further stereolithographic models. 64 Caucasian patients were enrolled, with ages between 19 and 93 years, both female and male volunteers, without previous surgical history of the middle floor of the face. Measurements were performed between certain craniometric points (Nasion, Dacryon, Infraorbital foramen, Rhinion and Frontomalare orbitale) and a database was created. RESULTS. Although some expected variation arised, we have obtained normal-considered intervals for each of the defined and measured segments between the mentioned craniometric points. We find these measurements useful especially for elaborating a presurgical plan for the best outcome. CONCLUSION. Simple measurements could orient a fast diagnosis, could help establish a surgical plan, an optimal surgical timing by combining clinical and imaging data.

Deep learning resting state functional magnetic resonance imaging lateralization of temporal lobe epilepsy.

Localization of focal epilepsy is critical for surgical treatment of refractory seizures. There remains a great need for noninvasive techniques to localize seizures for surgical decision-making. We investigate the use of deep learning using resting state functional magnetic resonance imaging (RS-fMRI) to identify the hemisphere of seizure onset in temporal lobe epilepsy (TLE) patients. A total of 2132 healthy controls and 32 preoperative TLE patients were studied. All participants underwent structural MRI and RS-fMRI. Healthy control data were used to generate training samples for a three-dimensional convolutional neural network (3DCNN). RS-fMRI was synthetically altered in randomly lateralized regions in the healthy control participants. The model was then trained to classify the hemisphere containing synthetic noise. Finally, the model was tested on TLE patients to assess its performance for detecting biological seizure onset zones, and gradient-weighted class activation mapping (Grad-CAM) identified the strongest predictive regions. The 3DCNN classified healthy control hemispheres known to contain synthetic noise with 96% accuracy, and TLE hemispheres clinically identified to be seizure onset zones with 90.6% accuracy. Grad-CAM identified a range of temporal, frontal, parietal, and subcortical regions that were strong anatomical predictors of the seizure onset zone, and the resting state networks that colocalized with Grad-CAM results included default mode, medial temporal, and dorsal attention networks. Lastly, in an analysis of a subset of patients with postsurgical outcomes, the 3DCNN leveraged a more focal set of regions to achieve classification in patients with Engel Class >I compared to Engel Class I. Noninvasive techniques capable of localizing the seizure onset zone could improve presurgical planning in patients with intractable epilepsy. We have demonstrated the ability of deep learning to identify the correct hemisphere of the seizure onset zone in TLE patients using RS-fMRI with high accuracy. This approach represents a novel technique of seizure lateralization that could improve preoperative surgical planning.

Fast-Track-Protocol for Optimization of Presurgical Planning in Acute Surgical Treatment of Acetabular Quadrilateral Plate Fractures Using 3D Printing Technology and Pre-Contoured Reconstruction Plates

Background. Preoperative planning and 3D printing can be used to treat pelvic bone fractures using pre-contoured surgical plates, in particular complex, comminuted fractures involving the acetabulum and quadrilateral plate. The aim of the study was to develop a Fast-Track-Protocol (fast track methodology) for creating 3D anatomical models, that could be used to shape surgical plates, using open-source software and budget 3D printers. Such a ‘low-budget’ approach would allow a hospital-based multidisciplinary team to carry out pre-surgical planning and treat complex pelvic fractures using 3D technology. Methods. The study included 5 patients with comminuted pelvic fractures. For each patient, CT (computed tomography) data were converted into two 3D models of the pelvis-injured side and mirrored model of the contralateral, uninjured hemipelvis. These models were 3D printed and used as templates to shape surgical plates. Results. A Fast-Track-Protocol was established and used to successfully treat 5 patients with complex, comminuted fractures of the pelvis. Conclusion. Using the Fast-Track-Protocol it was possible to prepare 3D printed models and patient-specific pre-contoured plates within 2 days of hospital admittance. Such an approach resulted in better surgical technique and shorter operative times, while incurring relatively low costs.

Inferior fronto-occipital fascicle displacement in temporoinsular gliomas using diffusion tensor imaging.

Background and PurposeBrain tumors can result in displacement or destruction of important white matter tracts such as the inferior fronto‐occipital fascicle (IFOF). Diffusion tensor imaging (DTI) can assess the extent of this effect and potentially provide neurosurgeons with an accurate map to guide tumor resection; analyze IFOF displacement patterns in temporoinsular gliomas based on tumor grading and topography in the temporal lobe; and assess whether these patterns follow a predictable pattern, to assist in maximal tumor resection while preserving IFOF function.MethodsThirty‐four patients with temporal gliomas and available presurgical MRI were recruited. Twenty‐two had insula infiltration. DTI deterministic region of interest (ROI)‐based tractography was performed using commercial software. Tumor topographic imaging characteristics analyzed were as follows: location in the temporal lobe and extent of extratemporal involvement. Qualitative tractographic data obtained from directional DTI color maps included type of involvement (displaced/edematous‐infiltrated/destroyed) and displacement direction. Quantitative tractographic data of ipsi‐ and contralateral IFOF included whole tract volume, fractional anisotropy, and fractional anisotropy of a 2‐dimensional coronal ROI on the tract at the point of maximum tumor involvement.ResultsThe most common tract involvement pattern was edematous/infiltrative displacement. Displacement patterns depended on main tumor location in the temporal lobe and presence of insular involvement. All tumors showed superior displacement pattern. In lateral tumors, displacement tendency was medial. In medial tumors, displacement tendency was lateral. When we add insular involvement, the tendency was more medial displacement. A qualitative and quantitative assessment supported these results.ConclusionsIFOF displacement patterns are reproducible and suitable for temporoinsular gliomas presurgical planning.

Use of 3-D Models for Surgical Planning of a Malunion in a Dog

Background An 8-year-old, 18.9 kg, male, intact Kai Ken with a femoral shaft fracture experienced recurrent implant breakage after two fracture reductions using an internal fixator. Objectives This case report is aimed at using a three-dimensional (3-D) printer to diagnose residual femoral rotational deviation. Implant failures and malunion occurred after two attempts at synthesis. Thus, a 3-D model was designed for preoperative planning of a third surgery. Methods To evaluate the alignment in the postoperative state after the second surgery, we removed a broken plate from the affected limb. Subsequently, a computed tomography image produced a bone replica using 3-D printing. The distal fragment was fixed and rotated externally by 42°. In addition to correcting the rotational deformity of the femur, we used an intramedullary pin and two locking plates to stabilize the proximal and distal femoral fracture segments. Results The bone union was confirmed four months after surgery, and no postoperative complications were observed 11 months after surgery. Conclusion 3-D printing is a valuable tool that increases the accuracy of presurgical planning.

Three-dimensional assessment of facial asymmetry in Class III subjects. Part 1: a retrospective study evaluating postsurgical outcomes

ObjectiveThe present study aimed to determine the site and severity of maxillomandibular asymmetry before and after orthognathic surgery in asymmetric patients.Materials and methodsPresurgery and postsurgery cone beam computed tomography (CBCT) data of 21 facial asymmetry patients (7 males and 14 females, mean age: 23.0 ± 3.36 years) with soft tissue chin deviation ≥ 3 mm who had undergone bimaxillary surgery were evaluated. Seven midline and twenty bilateral hard tissue landmarks were identified for the evaluation of facial asymmetry and outcomes were assessed against age- and gender-matched control subjects.ResultsIn the asymmetry group, bilateral landmarks exhibited significant deviation in the mandible and midface regions. Before surgery, asymmetry was more severe at the mandibular midline and sites close to it, in the asymmetry group. Bimaxillary surgery proved to be highly effective, with a significant correction of the menton to a clinically normal value (2.90 mm, p < 0.001). After surgery, significant residual asymmetry was observed at the mental foramen (p = 0.001) in the R-L direction. Moreover, significant asymmetry persisted at the sigmoid notch (p = 0.001) in the S-I direction.ConclusionsMandibular midline landmarks and chin peripheral regions contribute significantly to overall facial asymmetry characteristics. Despite significant correction after bimaxillary surgery, asymmetry persisted at several sites, thereby requiring secondary correction. Comprehensive 3D presurgical planning is central for asymmetry correction in a single surgery.Clinical relevanceThe present study specifies the location of residual asymmetry sites and advocates the correction of those sites during initial surgery.

Forearm and Hand Muscles Exhibit High Coactivation and Overlapping of Cortical Motor Representations

Most of the motor mapping procedures using navigated transcranial magnetic stimulation (nTMS) follow the conventional somatotopic organization of the primary motor cortex (M1) by assessing the representation of a particular target muscle, disregarding the possible coactivation of synergistic muscles. In turn, multiple reports describe a functional organization of the M1 with an overlapping among motor representations acting together to execute movements. In this context, the overlap degree among cortical representations of synergistic hand and forearm muscles remains an open question. This study aimed to evaluate the muscle coactivation and representation overlapping common to the grasping movement and its dependence on the stimulation parameters. The nTMS motor maps were obtained from one carpal muscle and two intrinsic hand muscles during rest. We quantified the overlapping motor maps in size (area and volume overlap degree) and topography (similarity and centroid Euclidean distance) parameters. We demonstrated that these muscle representations are highly overlapped and similar in shape. The overlap degrees involving the forearm muscle were significantly higher than only among the intrinsic hand muscles. Moreover, the stimulation intensity had a stronger effect on the size compared to the topography parameters. Our study contributes to a more detailed cortical motor representation towards a synergistic, functional arrangement of M1. Understanding the muscle group coactivation may provide more accurate motor maps when delineating the eloquent brain tissue during pre-surgical planning.

Digital technology in craniofacial surgery – Historical perspectives to current applications

Presurgical planning forms an important aspect of craniofacial surgery which involves repositioning and reconstruction of facial and skull bones. Digital technology is being increasingly used for planning surgical procedures. Virtual surgical planning, Computer-aided design and Computer-aided modeling greatly improve the speed, scope and accuracy of surgery thereby providing better patient outcomes and satisfaction. In cases of craniofacial anomalies, cutting and positioning guides can be fabricated. For orthognathic surgery, realistic predictions of outcomes can be provided, in addition to improved presurgical planning. In maxillofacial trauma, facial height, width and projection can be better restored. TMJ/Skull base resection and reconstruction can be performed as single-stage operation. Intraoperative and graft ischemic time is reduced during oncologic resection and reconstruction. Potential limitation is added cost but this is offset by benefits like significantly reduced operating time, better dental alignment and improved esthetic outcome. In this review we attempt to briefly describe the historical developments, detail the application and assess the impact of technology for surgical planning and outcome.

816 Traveling Waves Reveal a Dynamic Source of Human Focal Seizures and Interictal Spikes

INTRODUCTION: Treatment of patients with drug resistant focal epilepsy relies upon accurate seizure localization. Ictal activity captured in intracranial EEG (iEEG) has traditionally been interpreted to suggest that the underlying cortex is actively seizing. On the other hand, an emerging hypothesis suggests that seizures may in fact emerge from focal regions, which emit discharges that travel over the surface of the cortex as traveling waves. METHODS: 20 patients underwent placement of subdural electrodes for invasive monitoring at the National Instutes of Health, underwent surgical resection for epilepsy, and had at least 1 year of follow-up. Outcomes were measured by the Engel scale. In these patients, we measured the time delay in discharge receipt at adjacent electrodes to compute the location of the seizure source. This algorithm, known as multilateration, has been used for signal source localization with sparsely-spaced sensors for over a century in geophysics, radar, and acoustics, but has not been used in epilepsy until the present. RESULTS: In patients with good outcome, but not in patients with poor outcome, the seizure source tends to localize to the resection territory. The source is a focal, dynamic entity that moves and evolves over the time course of a seizure. Our approach also successfully localizes interictal spikes. We find that interictal spikes emerge from multiple distinct foci in each patient. Seizures either arise from or travel to interictal spike generators. CONCLUSIONS: The seizure source appears to be more focal than has traditionally been conceptualized. This focal source may be localized by measuring the time difference of discharge receipt in intracranial electrodes. Algorithmic source localization, as performed here, may guide pre-surgical planning for drug-resistant epilepsy and may improve outcomes.

Advanced Imaging Techniques for Newly Diagnosed and Recurrent Gliomas.

Management of gliomas following initial diagnosis requires thoughtful presurgical planning followed by regular imaging to monitor treatment response and survey for new tumor growth. Traditional MR imaging modalities such as T1 post-contrast and T2-weighted sequences have long been a staple of tumor diagnosis, surgical planning, and post-treatment surveillance. While these sequences remain integral in the management of gliomas, advances in imaging techniques have allowed for a more detailed characterization of tumor characteristics. Advanced MR sequences such as perfusion, diffusion, and susceptibility weighted imaging, as well as PET scans have emerged as valuable tools to inform clinical decision making and provide a non-invasive way to help distinguish between tumor recurrence and pseudoprogression. Furthermore, these advances in imaging have extended to the operating room and assist in making surgical resections safer. Nevertheless, surgery, chemotherapy, and radiation treatment continue to make the interpretation of MR changes difficult for glioma patients. As analytics and machine learning techniques improve, radiomics offers the potential to be more quantitative and personalized in the interpretation of imaging data for gliomas. In this review, we describe the role of these newer imaging modalities during the different stages of management for patients with gliomas, focusing on the pre-operative, post-operative, and surveillance periods. Finally, we discuss radiomics as a means of promoting personalized patient care in the future.