Biplane Fluoroscopy Research Articles

An Automated Three-Dimensional Bone Pose Tracking Method Using Clinical Interleaved Biplane Fluoroscopy Systems: Application to the Knee

Model-based tracking of the movement of the tibiofemoral joint via a biplane X-ray imaging system has been commonly used to reproduce its accurate, three-dimensional kinematics. To accommodate the approaches to existing clinical asynchronous biplane fluoroscopy systems and achieve comparable accuracy, this study proposed an automated model-based interleaved biplane fluoroscopy image tracking scheme (MIBFT) by incorporating information of adjacent image frames. The MIBFT was evaluated with a cadaveric study conducted on a knee specimen. The MIBFT reproduced skeletal poses and tibiofemoral kinematics that were in good agreement with the standard reference kinematics provided by an optical motion capture system, in which the root-mean-squared (Rms) errors of the skeletal pose parameters ranged from 0.11 to 0.35 mm in translation and 0.18 to 0.49° in rotation. The influences of rotation speed on the pose errors were below 0.23 mm and 0.26°. The MIBFT-determined bias, precision, and Rms error were comparable to those of the reported model-based tracking techniques using custom-made synchronous biplane fluoroscopy. The results suggested that the further use of the clinical imaging system is feasible for the noninvasive and precise examination of dynamic joint functions and kinematics in clinical practice and biomechanical research.

The impact of x-ray incident angle on indirect fluoroscopy skin dose estimation

Indirect dosimetry to calculate peak skin dose (PSD) is generally based on reference air kerma or kerma-area-product, with effects of table attenuation, inverse square law and backscatter factor applied. When the incident x-ray beam angle changes, these factors would change as well. The purpose of this study is to identify the impact of incident x-ray beam angle on the accuracy of indirect PSD calculation and develop a correction method. Monte Carlo simulation was conducted to assist analytical equation derivation and to validate the developed analytical method. Direct PSD measurements were performed a Siemens Artis Zee biplane fluoroscopy and a GE OEC C-Arm at different angles to validate the proposed correction method and its independence of fluoroscopy systems. Compared with MC simulated PSD, the derived analytical equation successfully predicts these PSD changes for incident angles of 0, 15, 30 and 40 degrees, with the residual error magnitude of 0.3%–3.1% corresponding to different SSDs. The agreement between calculated PSD also agrees well with direct measurement.

Cryoablation vs. radiofrequency ablation of the atrioventricular node in patients with His-bundle pacing.

Radiofrequency ablation (RFA) of the atrioventricular node (AVN) with His-bundle pacing (HBP) can cause rise in capture thresholds. Cryoablation (CRYO) may offer reversibility in case of threshold rise but has never been tested for AVN ablation in this setting. Our aim was to compare procedural characteristics and outcome of CRYO compared with RFA for AVN ablation in patients with HBP. Forty-four patients with HBP underwent AVN ablation for an 'ablate and pace' indication. Cryoablation was performed in the first 22 patients and RFA in the following 22 patients. Procedural characteristics, success rates, and change in His capture thresholds were compared between groups. Distance from the ablation site to the His lead was measured using biplane fluoroscopy. Acute success was 100% with both strategies. Median procedural duration was significantly longer for CRYO {50 [interquartile range (IQR) 38-63] min} compared with RFA [36 (IQR, 30-41) min; P = 0.027]. An acute threshold rise of ≥1 V was observed in four CRYO (one complete loss of capture) and three RFA patients (P = 0.38), with all of the applications being within 6 mm of the His lead tip. During follow-up, nine patients had AVN re-conduction (six CRYO vs. three RFA; P = 0.58), but only four patients required a redo procedure (all CRYO; P = 0.09). Cryoablation does not offer any advantage over RFA for AVN ablation in patients with HBP and tended to require more redo procedures. If possible, a distance of ≥6 mm should be maintained from the His lead tip to avoid a rise in capture thresholds.

Combining advanced computational and imaging techniques as a quantitative tool to estimate patellofemoral joint stress during downhill gait: A feasibility study

BackgroundThe onset and progression of patellofemoral osteoarthritis (OA) has been linked to alterations in cartilage stress—a potential precursor to pain and subsequent cartilage degradation. A lack in quantitative tools for objectively evaluating patellofemoral joint contact stress limits our understanding of pathomechanics associated with OA. Research questionCould computational modeling and biplane fluoroscopy techniques be used to discriminate in-vivo, subject-specific patellofemoral stress profiles in individuals with and without patellofemoral OA? MethodsThe current study employed a discrete element modeling framework driven by in-vivo, subject-specific kinematics during downhill gait to discriminate unique patellofemoral stress profiles in individuals with patellofemoral OA (n = 5) as compared to older individuals without OA (n = 6). All participants underwent biplane fluoroscopy kinematic tracking while walking on a declined instrumented treadmill. Subject-specific kinematics were combined with high resolution geometrical models to estimate patellofemoral joint contact stress during 0%, 25 %, 50 %, 75 % and 100 % of the loading response phase of downhill gait. ResultsIndividuals with patellofemoral OA demonstrated earlier increases in patellofemoral stress in the lateral patellofemoral compartment during loading response as compared to OA-free controls (P = 0.021). Overall, both groups exhibited increased patellofemoral contact stress early in the loading response phase of gait as compared to the end of loading response. Results from this study show increased stress profiles in individuals with patellofemoral OA, indicating increasing joint loading in early phases of gait. SignificanceThis modeling framework—combining arthrokinematics with discrete element models—can objectively estimate changes in patellofemoral joint stress, with potential applications to evaluate outcomes from various treatment programs, including surgical and non-surgical rehabilitation treatments.

Does double calibration coupled with a closed loop multibody kinematic optimization improve scapular kinematic estimates?

Assessment of scapular kinematics has been a challenging topic for several decades. While invasive procedures, such as biplanar fluoroscopy or intra cortical pins, have showed high accuracy to meas...

Evaluation of True Ankle Motion Following Total Ankle Replacement Utilizing XROMM technology

Category:Ankle ArthritisIntroduction/Purpose:Total ankle replacement (TAR) is common tool used by the foot and ankle specialist to treat end stage ankle arthritis. Current data about ankle motion following TAR is derived from gait analysis utilizing external markers. Utilizing Xray Reconstruction of Moving Morphology (XROMM), which combines 3-D mapping technology with biplanar fluoroscopy in vivo to visualize true skeletal motion, we can evaluate true motion of TAR implants. Current TAR replacement systems are either mobile bearing or fixed bearing. We hypothesized that subjects implanted with a fixed bearing prosthesis would exhibit less tibiotalar rotation and translation than subjects implanted with a mobile bearing prosthesis.Methods:Six subjects with total ankle replacement at least one-year post implantation gave informed consent before participating (IRB #H16496). Three subjects with a mobile bearing prosthesis with an average age 63.3+-11.1 yrs were compared to three matched subjects with a fixed bearing prosthesis with an average age of 64.7+-1.5 yrs. Utilizing 3D slicer software, lower body CT scans for each subject were evaluated to create 3D models of the foot and ankle bones and implant components. All subjects walked for several trials at a self-selected pace along a walkway while their foot and ankle motions were captured by a high-speed biplanar fluoroscopic x-ray motion analysis (XMA) system. The 3D models were combined with the x-ray images within a 3D animation platform and rotoscoped to resolve accurate kinematic motions at the tibiotalar joint during stance phase of gait. We examined for differences between the two groups using a two-sample t-test (p<0.05).Results:Subjects with a mobile-bearing prosthesis demonstrated mean ROM’s of 7.4+-1.1°, 5.3+-2.3° and 7.1+-4.3° for dorsiflexion/plantarflexion, inversion/eversion, and internal/external rotation, respectively. Subjects with a fixed bearing ankle prosthesis did not exhibit significantly different mean ROM’s for dorsiflexion/plantarflexion (9.1+-4.0°, p=0.35), inversion/eversion (4.4+-2.1°, p=0.42), and internal/external rotation (9.0+-3.4°, p=0.35), respectively. Subjects with a fixed bearing prosthesis displayed significantly more translation along the anteroposterior (3.6+-1.2mm, p<0.01) and mediolateral (2.2+-0.7mm, p<0.01) axes compared to the mobile bearing prosthesis (1.8+-1.2mm and 1.3+-0.8mm, respectively).Conclusion:Our preliminary results indicate that mobile and fixed bearing prosthesis provides similar angular motion at the tibiotalar joint, however, the fixed bearing prosthesis exhibits greater translational motion during walking. Further, there is the same amount of internal and external translation with both component designs. The implications of this work on success or failure of current implant designs is beyond the scope of this study but this work will provide the basis for future studies to help determine optimal future total ankle replacement designs.

A randomised comparison of monoplane versus biplane fluoroscopy in patients undergoing percutaneous coronary intervention: the RAMBO trial.

Interventional cardiologists are exposed to substantial occupational ionising radiation. This study sought to investigate differences in radiation exposure in biplane versus monoplane coronary angiography and percutaneous coronary interventions (PCI). RAMBO (RAdiation exposure in Monoplane versus Biplane cOronary angiography and interventions) was a prospective, randomised, two-arm, single-centre, open-label trial, enrolling a total of 430 patients undergoing coronary angiography. Patients were randomly assigned to biplane or monoplane imaging. The primary efficacy measure, the operator radiation dose at the level of the left arm as measured by a wearable electronic dosimeter, was significantly higher in the biplane as compared to the monoplane group (4 [1-13] µSv vs 2 [0-6.8] µSv, p<0.001). The dose area product was 11,955 (7,095-18,246) mGy*cm2 and 8,349 (5,851-14,159) mGy*cm2 in the biplane and the monoplane groups, respectively (p<0.001). While fluoroscopy time did not differ between the groups (p=0.89), the amount of contrast medium was lower with biplane as compared with monoplane imaging (p<0.001). Biplane imaging for coronary angiography and PCI is related to an increased radiation exposure for the interventional cardiologist as compared with monoplane imaging. Monoplane imaging should be considered for advanced radioprotection in cardiac catheterisation, with biplane imaging used for selected cases only.

Cervical spine intervertebral kinematics estimated from inverse kinematics and compared to dynamic X-ray data

Interpretation of shoulder motion across studies has been complicated due to the use of numerous scapular coordinate systems in the literature. Currently, there are no simple means by which to compare scapular kinematics between coordinate system definitions when data from only one coordinate system is known.How do scapular kinematics vary based on the choice of coordinate system and can average rotation matrices be used to accurately convert kinematics between scapular local coordinate systems?Average rotation matrices derived from anatomic landmarks of 51 cadaver scapulae (29 M/22 F; 59 ± 13 yrs; 26R/25 L; 171 ± 11 cm; 70 ± 19 kg; 23.7 ± 5.5 kg/m2) were generated between three common scapular coordinate systems. Absolute angle of rotation was used to determine if anatomical variability within the cadaver population influenced the matrices. To quantify the predictive capability to convert kinematics between the three coordinate systems, the average rotation matrices were applied to scapulothoracic motion data collected from 19 human subjects (10 M/9 F; 43 ± 17 yrs; 19R; 173 ± 9 cm; 71 ± 16 kg; 23.6 ± 4.5 kg/m2) using biplane fluoroscopy. Root mean squared error (RMSE) was used to compare kinematics from an original coordinate system to the kinematics expressed in each alternative coordinate system.The choice of scapular coordinate system resulted in mean differences in scapulothoracic rotation of up to 23°, with overall different shapes and/or magnitudes of the curves. A single average rotation matrix between any two coordinate systems achieved accurate conversion of scapulothoracic kinematics to within 4° of RMSE of the known solution. The average rotation matrices were independent of sex, side, decomposition sequence, and motion.Scapulothoracic kinematic representations vary in shape and magnitude based solely on the choice of local coordinate system. The results of this study enhance interpretability and reproducibility in expressing scapulothoracic motion data between laboratories by providing a simple means to convert data between common coordinate systems. This is necessitated by the variety of available motion analysis techniques and their respective scapular landmark definitions.

In Vivo Mechanical Function of the Distal Radial Ulnar Ligaments During Rotation of the Wrist

The purpose of this study was to investigate changes in length of the volar and dorsal radioulnar ligaments (VRULs and DRULs), and the distal radioulnar joint (DRUJ) space during unweighted and weighted rotation of the wrist using magnetic resonance imaging and biplanar fluoroscopy. Fourteen wrists in 7 normal adult volunteers were imaged to define the 3-dimensional geometry of the DRUJ and the insertion sites of the superficial and deep bundles of the VRULs and DRULs. Subjects were imaged at 10 positions of forearm rotation ranging from full pronation to full supination, with or without a 5-pound weight. Lengths of the superficial and deep VRUL and DRUL bundles and DRUJ space were measured (in millimeters) at each position to evaluate ligament function and DRUJ stability. In the unweighted and weighted trials, maximal elongation of both deep and superficial VRUL bundles occurred in supination and maximal lengths of the deep and superficial DRUL bundles occurred in pronation. Maximum DRUJ space occurred during pronation and a minimum occurred in 30° of supination. In weighted trials, there was a significant increase in deep and superficial VRUL bundle length at positions between 30° of pronation and 30° of supination; however, there was no effect of weight on DRULs length. In weighted trials, there was a significant increase in DRUJ space at positions between full pronation and 15° of supination. This study demonstrates elongation of the VRULs in supination and the DRULs in pronation. There was no evidence of reciprocal loading of superficial/deep ligament bundles on either the dorsal or the volar aspects of the DRUJ. The effect of loading the wrist during rotation was apparent primarily in the VRULs, but not the DRULs. The DRUJ space was lowest at approximately 30° of supination. These results add information to the literature regarding the complicated biomechanics of the triangular fibrocartilage complex and DRUJ. Future work should evaluate changes in biomechanics caused by triangular fibrocartilage complex tears to determine how tear severity and location relate to clinical symptoms.

A new method for estimating three-dimensional movement of the patella using a surface mapping method and computed tomography

IntroductionA previous study reported a method called the 2D-3D registration technique to examine three-dimensional movement of the patella. However, that method requires a biplane fluoroscopy system. In the present study, the aim was to establish a new method (CT-based surface mapping method) to estimate three-dimensional positions and angles of the patella with a motion capture system and CT. MethodsIn Study 1, the most appropriate parameters for the CT-based surface mapping method (i.e., target edge length, threshold of thickness of the soft tissue, and minimum distance between markers) were explored and determined. In Study 2, three-dimensional movement (i.e., positions and angles) of the patella using the CT-based surface mapping method and the most appropriate parameters were determined, and they were compared with the true positions and angles obtained by CT. ResultsThe results of Study 1 showed that the most appropriate conditions were as follows: (1) target edge length, 3 mm; (2) threshold of thickness of the soft tissue, 0–20 mm; and (3) minimum distance between markers, 10 mm. The results of Study 2 showed that the errors of the positions and angles were less than approximately 10 mm and 10° at most, respectively (both supine and sitting positions). ConclusionThe CT-based surface mapping method may be useful for a future study to clarify differences in three-dimensional movements of the patella between patients with patellar tendinitis and healthy subjects.

Reliable interpretation of scapular kinematics depends on coordinate system definition

BackgroundInterpretation of shoulder motion across studies has been complicated due to the use of numerous scapular coordinate systems in the literature. Currently, there are no simple means by which to compare scapular kinematics between coordinate system definitions when data from only one coordinate system is known. Research questionHow do scapular kinematics vary based on the choice of coordinate system and can average rotation matrices be used to accurately convert kinematics between scapular local coordinate systems? MethodsAverage rotation matrices derived from anatomic landmarks of 51 cadaver scapulae (29 M/22 F; 59 ± 13 yrs; 26R/25 L; 171 ± 11 cm; 70 ± 19 kg; 23.7 ± 5.5 kg/m2) were generated between three common scapular coordinate systems. Absolute angle of rotation was used to determine if anatomical variability within the cadaver population influenced the matrices. To quantify the predictive capability to convert kinematics between the three coordinate systems, the average rotation matrices were applied to scapulothoracic motion data collected from 19 human subjects (10 M/9 F; 43 ± 17 yrs; 19R; 173 ± 9 cm; 71 ± 16 kg; 23.6 ± 4.5 kg/m2) using biplane fluoroscopy. Root mean squared error (RMSE) was used to compare kinematics from an original coordinate system to the kinematics expressed in each alternative coordinate system. ResultsThe choice of scapular coordinate system resulted in mean differences in scapulothoracic rotation of up to 23°, with overall different shapes and/or magnitudes of the curves. A single average rotation matrix between any two coordinate systems achieved accurate conversion of scapulothoracic kinematics to within 4° of RMSE of the known solution. The average rotation matrices were independent of sex, side, decomposition sequence, and motion. SignificanceScapulothoracic kinematic representations vary in shape and magnitude based solely on the choice of local coordinate system. The results of this study enhance interpretability and reproducibility in expressing scapulothoracic motion data between laboratories by providing a simple means to convert data between common coordinate systems. This is necessitated by the variety of available motion analysis techniques and their respective scapular landmark definitions.

The relationship between tibiofemoral geometry and musculoskeletal function during normal activity

BackgroundThe effect of tibiofemoral geometry on musculoskeletal function is important to movement biomechanics. Research questionWe hypothesised that tibiofemoral geometry determines tibiofemoral motion and musculoskeletal function. We then aimed at 1) modelling tibiofemoral motion during normal activity as a function of tibiofemoral geometry in healthy adults; and 2) quantifying the effect of tibiofemoral geometry on musculoskeletal function. MethodsWe used motion data for six activity types and CT images of the knee from 12 healthy adults. Geometrical variation of the tibia and femoral articular surfaces were measured in the CT images. The geometry-based tibiofemoral motion was calculated by fitting a parallel mechanism to geometrical variation in the cohort. Matched musculoskeletal models embedding the geometry-based tibiofemoral joint motion and a common generic tibiofemoral motion of reference were generated and used to calculate joint angles, net joint moments, muscle and joint forces for the six activities analysed. The tibiofemoral model was validated against bi-planar fluoroscopy measurements for walking for all the six planes of motion. The effect of tibiofemoral geometry on musculoskeletal function was the difference between the geometry-based model and the model of reference. ResultsThe geometry-based tibiofemoral motion described the pattern and the variation during walking for all six motion components, except the pattern of anterior tibial translation. Tibiofemoral geometry had moderate effect on cohort-averages of musculoskeletal function (R2 = 0.60–1), although its effect was high in specific instances of the model, outputs and activities analysed, reaching 2.94 BW for the ankle reaction force during stair descent. In conclusion, tibiofemoral geometry is a major determinant of tibiofemoral motion during walking. SignificanceGeometrical variations of the tibiofemoral joint are important for studying musculoskeletal function during normal activity in specific individuals but not for studying cohort averages of musculoskeletal function. This finding expands current knowledge of movement biomechanics.

Stereotactic CT image guidance and biplanar fluoroscopy for transoral C2 vertebroplasty and direct anterolateral subaxial vertebroplasty: a surgical technique note on access to the axial and subaxial spine.

Metastatic cervical spine disease can cause compression fractures, cervical spine instability, and pain. Vertebroplasty can stabilize a fracture, reduce the pain associated with a compression fracture, prevent or stop the progression of a fracture, thus avoiding cervical spine fixation, and decreased mobility. Transoral C2 vertebroplasty is less invasive than open fusion surgery, but it poses its own risk of infection and cement leak in this highly sensitive area. The image guidance setup consisted of the Stryker NAV3i navigation system, Stryker CranialMask tracker, and the CranialMap3.0 software combined with biplanar fluoroscopy. The patient's neck pain has completely resolved immediately after the surgery. There were no complications. Quality of life preservation is paramount in the management of metastatic spine disease. Vertebroplasty of osteolytic lesions can both relieve pain and restore stability, thus avoiding permanent stiff cervical collar, halo vest, or upfront occipitocervical fusion. With the increasing availability of surgical navigation systems, its use combined with biplanar fluoroscopy for performing transoral C2 vertebroplasty seems to be an adequate treatment in selected cases for pain relief, stabilization, and maintaining quality of life in the complex cancer population with C2 pathological fractures. The article describes as well vertebroplasty of the subaxial spine through a conventional anterior approach which again seems to be adequate in the treatment of spinal pathological fractures. Graphical abstract.

Neuronavigation Assistance. Decreased radiation exposure during spinal surgery in patients with severe combined trauma

Absnract. The results of the study of intraoperative x-ray irradiation of the affected two arrays are presented: the main array using neuronavigation and the control group, where standard 2D fluoroscopy was used. The radiation load on the operating surgeon and auxiliary operating personnel was also evaluated. Intraoperative visualization was carried out using the second-generation iNtellect ENT Navigation rack of the Stryker company (United States of America) for the victims of the main array and the Ziehm Vision RFD optical-optical converter (Germany) of the company for the victims of the control group. The imaging option using an electron-optical transducer is especially important for minimally invasive procedures, where instrumentation is performed percutaneously without direct anatomical control, as opposed to open procedures or working with distorted anatomical structures during injuries. Biplanar fluoroscopy was one of the first intraoperative methods of imaging in real time, and remains one of the leading technologies in orthopedic and spinal surgery. However, radiation exposure from intraoperative fluoroscopy remains a serious problem for patients, surgeons, and operating support staff. The negative effect of ionizing radiation leads to cell damage through the induction of deoxyribonucleic acid and the release of reactive oxygen species. In this regard, cell death or genome instability occurs, which leads to various radiation-related pathologies. It was found that the use of neuronavigation reduces the number of errors, reduces intraoperative trauma, and significantly reduces intraoperative radiation exposure to the injured, operating surgeon and auxiliary operating personnel. The large-scale introduction of navigation technologies will reduce or completely eliminate the harmful effects of ionizing radiation on the injured and medical personnel.

A minimally invasive approach for the treatment of isolated type intracranial dural arteriovenous fistula in a neurosurgical hybrid operating room

ObjectivesIsolated-type intracranial dural arteriovenous fistulas (DAVFs) could hinder the effective use of the transvenous approach. Direct trans-sinus embolization (dTSE) with craniotomy remains the treatment method for isolated-type DAVFs. We report our experience in using a neurosurgical hybrid operating room (NHOR) to treat cases of isolated-type DAVFs by dTSE using a single burr hole. Patients and methodsBetween April 2007 and March 2017, 189 DAVFs were treated by an endovascular procedure at our institution. Among these cases, 27 patients (14.3%) had isolated-type DAVF and 7 patients (3.7%) were treated by dTSE. The procedure accuracy and invasiveness of dTSE were compared with those of the transvenous embolization (TVE) group.The NHOR was equipped with a biplane angiography system and used to perform 3D rotational angiography (3DRA). The burr hole site was precisely determined by 3DRA. Only one burr hole was made to expose the target sinus and allow for direct puncture. The target sinus was occluded by using coils and liquid embolic material. ResultsThe NHOR allowed the accurate placement of the burr hole. Only a single burr hole and small skin incision (with minimal bleeding) were required for each dTSE case. The mean total contrast volume was significantly reduced in the dTSE group compared with that in the TVE group. Moreover, the dTSE group required shorter operation times and lower total radiation doses compared with the TVE group. ConclusionUsing dTSE could be performed with a single burr hole using a NHOR equipped with biplanar fluoroscopy. This approach is a minimally invasive and effective treatment for isolated-type DAVFs.

Impression Methods for Custom Foot Orthoses—Comparing Semi–Weight-Bearing Foam and Non–Weight-Bearing Plaster Using a Kinematic Measurement of the Medial Longitudinal Arch

ABSTRACT INTRODUCTION One of the goals for custom foot orthoses (CFOs) is to provide relief for pressure-sensitive areas and provide support to the joints of the foot for an optimal weight-bearing position. The most common CFO impression methods used by practitioners include plaster bandage, foam box, fiberglass, and laser-optical scanning, and are often compared by measuring foot molds created from those methods. The objective of this study is to compare the biomechanical effects of CFOs made from two common casting methods using skeletal kinematics. MATERIALS AND METHODS The medial longitudinal arch (MLA) angle was measured for 13 participants of different foot types: five pes planus, four pes cavus, and four normally arched. Four conditions were compared: barefoot, shod, and CFOs made from both semi-weight-bearing foam and non-weight-bearing plaster casting methods. The MLA angle was measured from three-dimensional bone models using biplane fluoroscopy images during midstance. RESULTS Foam (P = 0.02) and plaster (P = 0.01) cast foot orthoses were significantly different from the barefoot condition, and the shod condition was significantly different from both foam (P = 0.004) and plaster (P = 0.014) cast orthoses. No statistically significant differences were found when comparing the two casting methods: non-weight-bearing plaster and semi-weight-bearing foam (P = 0.170). CONCLUSIONS Clinicians favoring one particular style of casting can feel confident, for the patient set described, that either choice will produce similar biomechanical outcomes with respect to foot kinematics.

Technical considerations and challenges in treatment of a ruptured PICA aneurysm in a morbidly obese patient

Morbid obesity presents unique challenges in the treatment of many neurosurgical conditions. In ruptured posterior circulation aneurysms, endovascular treatment has emerged as the safest and most efficacious treatment modality in the majority of cases. We present a technical report of a patient with extensive subarachnoid hemorrhage from a ruptured distal PICA aneurysm. The patient was taken to the hybrid OR with biplane fluoroscopy, utilizing a unique operative set-up to enable safe endovascular treatment. The PICA aneurysm was treated via a transradial approach with distal PICA occlusion using Onyx liquid embolysate. The patient remained neurologically intact and was discharged home after 14 days. This case illustrates a number of technical adjustments that may be made in the safe treatment of patients in whom obesity otherwise limits treatment options.

Robust Self-Supervised Learning of Deterministic Errors in Single-Plane (Monoplanar) and Dual-Plane (Biplanar) X-Ray Fluoroscopy

Fluoroscopic imaging that captures X-ray images at video framerates is advantageous for guiding catheter insertions by vascular surgeons and interventional radiologists. Visualizing the dynamical movements non-invasively allows complex surgical procedures to be performed with less trauma to the patient. To improve surgical precision, endovascular procedures can benefit from more accurate fluoroscopy data via calibration. This paper presents a robust self-calibration algorithm suitable for single-plane and dual-plane fluoroscopy. A three-dimensional (3D) target field was imaged by the fluoroscope in a strong geometric network configuration. The unknown 3D positions of targets and the fluoroscope pose were estimated simultaneously by maximizing the likelihood of the Student-t probability distribution function. A smoothed k-nearest-neighbour (kNN) regression is then used to model the deterministic component of the image reprojection error of the robust bundle adjustment. The Maximum Likelihood Estimation step and the kNN regression step are then repeated iteratively until convergence. Four different error modeling schemes were compared while varying the quantity of training images. It was found that using a smoothed kNN regression can automatically model the systematic errors in fluoroscopy with similar accuracy as a human expert using a small training dataset. When all training images were used, the 3D mapping error was reduced from 0.61-0.83 mm to 0.04 mm post-calibration (94.2-95.7% improvement), and the 2D reprojection error was reduced from 1.17-1.31 to 0.20-0.21 pixels (83.2-83.8% improvement). When using biplanar fluoroscopy, the 3D measurement accuracy of the system improved from 0.60 mm to 0.32 mm (47.2% improvement).

A salamander that chews using complex, three-dimensional mandible movements.

Most non-mammal tetrapods have a hinge-like jaw operation restricted to vertical opening and closing movements. Many mammal jaw joints, by contrast, operate in more complex, three-dimensional (3D) ways, involving not only vertical but also propalinal (rostro-caudal) and transverse (lateral) movements. Data on intraoral food processing in lissamphibians and sauropsids has prompted a generally accepted view that these groups mostly swallow food unreduced, and that in those cases where lissamphibians and sauropsids chew, they mostly use simple vertical jaw movements for food processing. The exception to this generally accepted view is the occurrence of some propalinal chewing in sauropsids. We combined 3D kinematics and morphological analyses from biplanar high-speed video fluoroscopy and micro-computed tomography to determine how the paedomorphic salamander Siren intermedia treats captured food. We discovered not only that S. intermedia uses intraoral food processing but also that the elaborated morphology of its jaw joint facilitates mandibular motions in all three planes, resulting in complex 3D chewing. Thus, our data challenge the commonly held view that complex 3D chewing movements are exclusive to mammals, by suggesting that such mechanisms might have evolved early in the tetrapod evolution.

Biplanar Fluoroscopy in Pediatric Orthopaedics

Biplanar fluoroscopy allows for the simultaneous acquisition of x-ray images in 2 planes without needing to move the extremity or C-arm. It is advantageous in cases such as pinning supracondylar humerus fractures or slipped capital femoral epiphyses where frequently alternating between 2 planes under fluoroscopic imaging is required. However, literature describing the technique is lacking. Therefore, the purpose of our article is to discuss room setup, advantages, and disadvantages of using biplanar fluoroscopy in cases involving the elbow, shoulder, hip, and knee.