Postprocedural Computed Tomography Research Articles

Incidence, progression, and predictors of left atrial appendage sealing after Watchman FLX device implantation with computed tomographic assessment.

Limited data exists regarding incidence, progression, and predictors of left atrial appendage (LAA) sealing after transcatheter LAA closure. We aimed to evaluate the incidence, progression, and predictive factors associated with LAA sealing after LAA closure. This study includes patients who underwent successful LAA closure with Watchman FLX device and had both pre- and postprocedural computed tomography (CT). Postprocedural CT was performed 45 days after LAA closure and used to evaluate residual LAA patency. Patient who had residual LAA patency at 45 days underwent 1-year follow-up CT. A total of 105 patients (mean age: 75.2 ± 9.6 years; 53.3% female) who underwent successful LAA closure with Watchman FLX device and had pre- and postprocedural CT at 45 days were included. Residual patency was observed in 35 (33.3%) patients: 21 (20.0%) patients showed complete contrast opacification in LAA (complete LAA patency) while 14 (13.3%) patients showed contrast opacification only in the distal LAA (distal LAA patency). Among patients with residual LAA patency at 45 days, the rate of LAA sealing at 1 year was significantly higher in the distal LAA patency group than in the complete LAA patency group (75.0% vs. 16.7%; p = 0.019). Increased depth oversizing was associated with both distal LAA patency and complete LAA patency. Postprocedural CT at 45 days detected patent LAA in one-third of patients after LAA closure. LAA sealing was more frequently observed at 1 year among the distal LAA patency group than the complete LAA patency group.

Balloon Dilatation for Bronchoscope Delivery in a Swine Model: A Novel Technique for Ultra-Peripheral Lung Field Access and Accurate Biopsy.

In transbronchial biopsy of peripheral pulmonary lesions, the bronchoscope can reach only a limited depth due to the progressive narrowing of bronchi, which may reduce the diagnostic rate. This study examined the balloon dilatation for bronchoscope delivery (BDBD) technique, employing a novel balloon device to enhance bronchoscopy into the peripheral lung areas. Anaesthetised swine served as our primary model. Using computed tomography (CT) scans, we positioned virtual targets characterised by a positive bronchus sign and a diameter of 20 mm beneath the pleura. The bronchoscope was navigated along the pathways determined from the CT images. We performed balloon dilatation when bronchial narrowing obstructed progress to assess whether balloon dilatation would enable the bronchoscope to enter further into the periphery. We established 21 virtual targets on the CT scans. An average of 12.1 branches were identified along the pathways on the CT scans; however, bronchoscopy without BDBD only allowed access to an average of 6.7 branches. Based on 72 balloon dilatations with 3.0-mm or 4.0-mm ultra-thin bronchoscopes, there was an average increased access of 3.43 and 5.14 branches per route, respectively, with no significant BDBD complications. The bronchoscope was able to reach the planned location along all pathways, and the mean final bronchoscopic endpoints were at an average distance of 14.7 mm from the pleura. Post-procedure CT confirmed biopsy accuracy. The BDBD technique can enhance access of a flexible bronchoscope into the peripheral lung fields, which could potentially allow more accurate transbronchial interventions for peripheral targets.

Stereotactic brain Interventions: Identifying risks for biopsy failures and hemorrhage

BackgroundThe advent of computed tomography (CT) and magnetic resonance imaging (MRI) has revolutionized stereotactic brain interventions, which enabled precise targeting of deep brain structures and enhanced patient safety in modern neurosurgery. This study aims to investigate the risk factors associated with biopsy failure and hemorrhage in CT-guided brain stereotactic surgeries. MethodsIn the current study, we present a retrospective descriptive analysis of cases that showed biopsy failures and hemorrhage after CT-guided stereotactic brain biopsy surgeries at our department from January 2019 to January 2021. Biopsies were obtained using a Sedan-type needle. ResultsOut of the 80 patients who underwent CT-guided stereotactic surgeries, two patients (2.5 %) experienced biopsy failure, necessitating a repeat procedure. There was a notably higher risk of biopsy failure when fewer than four biopsy attempts were made (adjusted odds ratio = 6.4, 95 % CI 1.8 to 16.7). A postprocedural CT scan revealed intracranial hemorrhage in five patients (6.25 %); four of these cases were silent, with no accompanying neurological complications. Four out of the five hemorrhage cases were associated with astrocytoma. ConclusionsStereotactic surgery provides a precise and minimally invasive approach to target lesions with a relatively low risk of biopsy failures and hemorrhage.

Endoscope-Assisted Visualization of the Internal Auditory Canal Using the Middle Fossa Approach.

Angled endoscopes have been postulated to increase visualization of the internal auditory canal (IAC); however, few studies have quantified the extent of IAC visualization using endoscopes of varying angles. Preservation of the bony labyrinth in middle fossa (MF) vestibular schwannoma surgery may limit visualization of the lateral IAC. We sought to determine the extent to which IAC visualization is increased with endoscopes in these situations. Computed tomography (CT) scans were acquired before and after two cadaveric MF bony drill-outs. An atlas-based method was used to localize the IAC in the preprocedure CT and then registered with the postprocedure CT using standard image registration methods. Virtual microscope and endoscope positions and angles of approach were determined in a 3D rendering environment. Using ray casting techniques, the percentage of IAC surface area visible (unobscured by bony structures) with the microscope and 0°, 30°, and 45° endoscopes was calculated. For cadaver 1, the microscope led to visible IAC surface areas of 72%, whereas 0°, 30°, and 45° endoscopes visualized 58%, 79%, and 84%, respectively. For cadaver 2, the microscope led to visible surface areas of 67%, whereas the same endoscopes visualized 66%, 84%, and 84%, respectively. Using a microscope yields similar proportions of visible IAC surface area to a 0° endoscope in MF bony drill-outs. Increased visualization of the IAC is possible with more angled endoscopes. Using angled endoscopes may facilitate improved tumor dissection in the lateral IAC with neural and vascular preservation in vestibular schwannoma surgery aimed at hearing preservation.

Transcatheter closure of postsurgical aortic pseudoaneurysms guided by three-dimensional image reconstruction: asingle-centre experience.

Postsurgical thoracic aortic pseudoaneurysms (PTAPs) are apotentially lethal complication after cardiac or aortic surgery. Surgical management can pose achallenge with high in-hospital mortality rates. Transcatheter closure is aless-invasive alternative treatment option for selected patients, although current experience is limited. We aimed to evaluate procedural and imaging outcomes of our first 11cases of transcatheter PTAP closure with the use of closure devices. Patients with ahigh operative risk who underwent transcatheter PTAP closure at our centre from 2019 to 2021 were retrospectively included. Suitability was evaluated on preprocedural computed tomography (CT) scans and three-dimensional (3D) reconstructions. All procedures were performed in the catheterisation laboratory. Intraprocedural aortography and postprocedural CT scans with 3D reconstructions were used to evaluate PTAP occlusion. Eleven consecutive patients with ahigh operative risk and ahistory of cardiac/aortic surgery who underwent transcatheter PTAP closure were included. PTAPs were predominantly located at the proximal or distal anastomosis of asupracoronary ascending aortic vascular graft or Bentall prosthesis (82%). Implanted closure devices included Amplatzer Valvular PlugIII (82%), Amplatzer septal occluder (9%) and Occlutech atrial septal defect occluder (9%). No periprocedural complications occurred. After device deployment, residual flow was absent on aortography in 64% and minimal residual flow was present in 36% of patients. Subtotal or total occlusion of the PTAP on follow-up CT ranged between 45% and 73%. Although subtotal or total occlusion of the PTAP was found at follow-up in only 45-73% of cases, transcatheter PTAP closure guided by preprocedural 3D reconstructions can offer avaluable minimally invasive primary treatment option for patients who otherwise would face ahigh-risk reoperation.

Computed tomography-guided stereotactic surgery in the management of brain lesions: A single-center experience.

The present study presents our experience with computed tomography (CT)-guided stereotactic surgery in managing deep-seated brain lesions and provides a background in the expanding fields of morphological stereotactic neurosurgery. We conducted this retrospective cohort study on 80 patients managed at the Department of Neurosurgery, Zagazig University Hospitals, Zagazig, Egypt, between January 2019 to January 2021. We targeted patients with morphological stereotactic surgeries performed as the primary management modality of their treatment. A total of 80 patients, with a mean age of 44.3 years, were included in the study. The stereotactic targets were supratentorial in 71 patients (88.75%), infratentorial in seven patients (8.75%), and both supraand infratentorial in two patients (2.5%). The lesions showed enhancements with IV contrast in 55 patients (68.75%). Stereotactic procedures were performed under local anesthesia in 64 patients and general anesthesia in 16 patients. Of the 80 stereotactic procedures, 52 were biopsies (65%). We observed a significant improvement in the postoperative Karnofsky performance score compared to the postoperative score (63.4 ± 19.8 vs. 56.7 ± 15.4, P = 0.001). The level of agreement between clinical, radiological, and final pathological diagnosis was assessed; it was complete in 47.5% of the patients. The postprocedural CT scan demonstrated intracranial hemorrhage in five patients (6.25%); four (5%) were silent with no neurological complications. This study provided evidence that the stereotactic procedure is easy to perform, accurate in targeting the lesion, and spares patients from undergoing major surgical procedures. Stereotactic applications of spontaneous intracerebral hemorrhage, deep-seated abscesses, encysted tumors, or medically refractory benign intracranial hypertension can improve the outcome even in medically high-risk patients.

Phlegmasia cerulea dolens with lower leg compartment syndrome.

A 57-year-old man with a history of human immunodeficiency virus infection presented with sudden pain and swelling of the right leg that had developed over the preceding thirty minutes (Panel A). He reported having been taking antiretroviral drugs. Computed tomography (CT) demonstrates partial pulmonary artery embolism and massive deep vein thrombosis extending from the right external iliac to the popliteal veins. Despite commencing anticoagulation, he had severe pain and intense dysesthesia of the right leg. The intramuscular pressure in his right leg was 98 mmHg (reference: <10 mmHg), and his right dorsalis pedis pulse was not palpable. A clinical diagnosis of compartment syndrome secondary to phlegmasia cerulea dolens was made, and he underwent immediate fasciotomy (Panel B). As the dysesthesias did not improve by fasciotomy, catheter-directed venous thrombectomy was performed on day 5 of hospitalization using a 10-French Heartrail ST01 catheter (Terumo, Tokyo, Japan) via a cross-over 12-French DrySeal (WL Gore, Flagstaff, Arizona, USA) from the contralateral femoral vein after placing an inferior vena cava (IVC) filter. Although the final venography revealed restored venous flow, the filter could not be retrieved because of trapped thrombi (Panel C-E, see supplementary data online, Videos S1–S3). Postprocedural CT demonstrated complete thrombosis of the right external iliac vein, and swelling in the right thigh was persistent despite anticoagulation and intermittent pneumatic compression. After the second venous thrombectomy on day 15, the venous flow was completely restored, and the filter was retrieved (see supplementary data online, Videos S4 and S5). He was discharged on apixaban without symptoms of post-thrombotic syndrome (Panel F).

CT features and risk factors of pulmonary cement embolism after vertebroplasty or kyphoplasty in patients with vertebral compression fracture: a retrospective cohort study.

Pulmonary cement embolism (PCE) caused by cement leakage is one of the complications of percutaneous vertebroplasty (PVP) or percutaneous kyphoplasty (PKP). The aim of our study was to explore the imaging features on computed tomography (CT) and analyze the risk factors of PCE in patients with a vertebral compression fracture to compare the incidences of PCE caused by PVP and PKP. In this single-center, retrospective study, 373 patients (96 males and 277 females; mean age 76.2±9.4 years) from January 2017 to December 2020 who underwent PVP or PKP for treatment of vertebral compression fracture in the China-Japan Friendship Hospital were retrospectively included. Their clinical data were recorded, and their postprocedural chest CT scans were reviewed and evaluated for PCE. Of the 373 patients, 258 patients underwent PVP while the other 115 underwent PKP. PCE was found on the postprocedural chest CT scans in 64 patients (17.2%), including 47 patients with PVP and 17 patients with PKP. The incidence of PCE of PVP and PKP was similar (χ2=0.660; P=0.460). The typical CT findings of PCE were multiple linear or branching radiopaque densities in pulmonary arteries. The upper lobes of bilateral lungs were the most frequently involved. In addition, postprocedural chest CT demonstrated that 103 cases had cement emboli in the azygos vein, and 8 cases had cement emboli in the inferior vena cava. Binary logistic regression analysis demonstrated that PVP or PKP in the T9 vertebra [odds ratio (OR) =4.222; 95% CI: 1.490-11.966] and cement emboli in the azygos vein (OR =7.647; 95% CI: 3.937-14.856) or the inferior vena cava (OR =42.701; 95% CI: 7.525-242.302) were the risk factors of PCE. The incidence of PCE during PVP or PKP was 17.2%. Postprocedural chest CT clearly showed PCE as branching hyperdense or radiopaque lesions confined within the pulmonary artery courses. PVP or PKP in the T9 vertebra and cement emboli in the azygos vein or the inferior vena cava were risk factors for PCE.

Multimodality annotated hepatocellular carcinoma data set including pre- and post-TACE with imaging segmentation

Hepatocellular carcinoma (HCC) is the most common primary liver neoplasm, and its incidence has doubled over the past two decades owing to increasing risk factors. Despite surveillance, most HCC cases are diagnosed at advanced stages and can only be treated using transarterial chemo-embolization (TACE) or systemic therapy. TACE failure may occur with incidence reaching up to 60% of cases, leaving patients with a financial and emotional burden. Radiomics has emerged as a new tool capable of predicting tumor response to TACE from pre-procedural computed tomography (CT) studies. This data report defines the HCC-TACE data collection of confirmed HCC patients who underwent TACE and have pre- and post-procedure CT imaging studies and available treatment outcomes (time-to-progression and overall survival). Clinically curated segmentation of pre-procedural CT studies was done for the purpose of algorithm training for prediction and automatic liver tumor segmentation.

Identifying fragile calcifications of the aortic valve in transcatheter aortic valve replacement: iodine concentration of aortic valvular calcification by spectral CT.

To demonstrate the relationship between spectral computed tomography (CT) measured iodine concentration and strength of aortic valvular calcification (AVC) in patients with aortic valve stenosis (AVS). A retrospective study was performed on patients who underwent transcatheter aortic valve replacement (TAVR) for symptomatic AVS and underwent both pre and postprocedural electrocardiogram gated CT scans using a spectral CT system. Preprocedural CT was used to evaluate the volume and iodine concentration (IC) in the AVC. Postprocedural CT data were used to calculate the volume reduction percentage (VRP) of AVC. Multiple linear regression analysis was used to identify the independent variables related to the VRP in AVCs. A total of 94 AVCs were selected from 22 patients. The mean volume and IC of the AVCs before TAVR were 0.37 mL ± 0.15 mL and 7 mg/mL ± 10.5 mg/mL, respectively. After TAVR, a median VRP of all 94 AVCs was 18.5%. Multiple linear regression analysis showed that the IC was independently associated with the VRP (coefficient = 1.64, p < 0.001). When an optimal IC cutoff point was set at 4 mg/mL in the assessment of a fragile AVC which showed the VRP was > 18.5%, the sensitivity was 63%; specificity, 91%; positive predictive value, 88%; and negative predictive value, 71%. When using spectral CT to prepare the TAVR, measuring the IC of the AVC may be useful to assess the probability of AVC deformity after TAVR. • A dual-layer detector-based spectral CT enables quantifying iodine of contrast media in the aortic valve calcification (AVC) on contrast-enhanced CT images. • The AVC including iodine of contrast media on contrast-enhanced CT image may have loose compositions, associated with the deformity of AVC after TAVR. • Measuring the iodine concentration in AVC may have the potential to assess the probability of AVC deformity, which may be associated with the outcome and complications after TAVR.2.

Coronary access following ACURATE neo implantation for transcatheter aortic valve-in-valve implantation: Ex vivo analysis in patient-specific anatomies.

BackgroundCoronary access after transcatheter aortic valve implantation (TAVI) with supra-annular self-expandable valves may be challenging or un-feasible. There is little data concerning coronary access following transcatheter aortic valve-in-valve implantation (ViV-TAVI) for degenerated surgical bioprosthesis.AimsTo evaluate the feasibility and challenge of coronary access after ViV-TAVI with the supra-annular self-expandable ACURATE neo valve.Materials and methodsSixteen patients underwent ViV-TAVI with the ACURATE neo valve. Post-procedural computed tomography (CT) was used to create 3D-printed life-sized patient-specific models for bench-testing of coronary cannulation. Primary endpoint was feasibility of diagnostic angiography and PCI. Secondary endpoints included incidence of challenging cannulation for both diagnostic catheters (DC) and guiding catheters (GC). The association between challenging cannulations with aortic and transcatheter/surgical valve geometry was evaluated using pre and post-procedural CT scans.ResultsDiagnostic angiography and PCI were feasible for 97 and 95% of models respectively. All non-feasible procedures occurred in ostia that underwent prophylactic “chimney” stenting. DC cannulation was challenging in 17% of models and was associated with a narrower SoV width (30 vs. 35 mm, p < 0.01), STJ width (28 vs. 32 mm, p < 0.05) and shorter STJ height (15 vs. 17 mm, p < 0.05). GC cannulation was challenging in 23% of models and was associated with narrower STJ width (28 vs. 32 mm, p < 0.05), smaller transcatheter-to-coronary distance (5 vs. 9.2 mm, p < 0.05) and a worse coronary-commissural overlap angle (14.3° vs. 25.6o, p < 0.01). Advanced techniques to achieve GC cannulation were required in 22/64 (34%) of cases.ConclusionIn this exploratory bench analysis, diagnostic angiography and PCI was feasible in almost all cases following ViV-TAVI with the ACURATE neo valve. Prophylactic coronary stenting, higher implantation, narrower aortic sinus dimensions and commissural misalignment were associated with an increased challenge of coronary cannulation.

Assessing the Hemodynamic Impact of Anterior Leaflet Laceration in Transcatheter Mitral Valve Replacement: An in silico Study.

BackgroundA clinical study comparing the hemodynamic outcomes of transcatheter mitral valve replacement (TMVR) with vs. without Laceration of the Anterior Mitral leaflet to Prevent Outflow Obstruction (LAMPOON) has never been designed nor conducted.AimsTo quantify the hemodynamic impact of LAMPOON in TMVR using patient-specific computational (in silico) models.MaterialsEight subjects from the LAMPOON investigational device exemption trial were included who had acceptable computed tomography (CT) data for analysis. All subjects were anticipated to be at prohibitive risk of left ventricular outflow tract (LVOT) obstruction from TMVR, and underwent successful LAMPOON immediately followed by TMVR. Using post-procedure CT scans, two 3D anatomical models were created for each subject: (1) TMVR with LAMPOON (performed procedure), and (2) TMVR without LAMPOON (virtual control). A validated computational fluid dynamics (CFD) paradigm was then used to simulate the hemodynamic outcomes for each condition.ResultsLAMPOON exposed on average 2 ± 0.6 transcatheter valve cells (70 ± 20 mm2 total increase in outflow area) which provided an additional pathway for flow into the LVOT. As compared to TMVR without LAMPOON, TMVR with LAMPOON resulted in lower peak LVOT velocity, lower peak LVOT gradient, and higher peak LVOT effective orifice area by 0.4 ± 0.3 m/s (14 ± 7% improvement, p = 0.006), 7.6 ± 10.9 mmHg (31 ± 17% improvement, p = 0.01), and 0.2 ± 0.1 cm2 (17 ± 9% improvement, p = 0.002), respectively.ConclusionThis was the first study to permit a quantitative, patient-specific comparison of LVOT hemodynamics following TMVR with and without LAMPOON. The LAMPOON procedure achieved a critical increment in outflow area which was effective for improving LVOT hemodynamics, particularly for subjects with a small neo-left ventricular outflow tract (neo-LVOT).

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.

Accuracy of Patient-Specific Drill Guide Template for Bilateral C1-C2 Laminar Screw Placement: A Cadaveric Study

We sought to evaluate the accuracy of using patient-specific drill guides to place bilateral laminar screws in C1 and C2. Nine cervical specimens (8 males; mean age: 66.6 [56-73]) with the occiput attached (C0-C3) were used in this study. Preoperative computed tomography (CT) scans were used to create digital anatomic models for templating and guide creation. A total of 36 screws were placed with the aid of 3-dimensional printed, patient-specific guides (2 screws at C1 and C2). Postoperative CT scans were performed following screw insertion. The planned and actual trajectories were compared using preoperative and postoperative imaging based on the angular and entry point deviation. After screw placement and postoperative imaging, each specimen was dissected and performed a visual inspection for breaches. No breaches or violations were observed on postprocedural CT and visual inspection. The average variation of the entry point in the X, Y, and Z axes was 0.3 ± 0.28, 0.41 ± 0.38, and 0.29 ± 0.24, respectively. No statistically significant difference (P > 0.05) was observed between the planned and obtained entry points. There was no significant difference (P > 0.05) in the deviation analysis between the planned and obtained angles in the axial and coronal planes. The study demonstrates that patient-specific drill guides allow for accurate C1 and C2 bilateral laminar screw placement, with a low risk of cortical breach.

Risk Assessment of Coronary Obstruction During Transcatheter Aortic Valve Replacement

The aim of this study was to examine the predictive value of preprocedural computed tomography (CT)-based risk stratification of coronary obstruction during transcatheter aortic valve replacement (TAVR) on the basis of geometric measurements on postprocedural CT.Proper patient selection for additional procedures to prevent coronary obstruction during TAVR has not been adequately evaluated.Pre- and postprocedural computed tomographic scans of 28 patients treated using bioprosthetic or native aortic scallop intentional laceration to prevent iatrogenic coronary artery obstruction (BASILICA) and TAVR were analyzed. Using the postprocedural computed tomographic images, threatened coronary obstruction (TCO) was defined as: 1) ostial obstruction (adherence of the transcatheter heart valve [THV] to the coronary ostium with leaflet extension above the ostium); and/or 2) sinus sequestration (THV adherence to the sinotubular junction [STJ] with leaflet extension above the STJ) and was substratified into complete and incomplete types.A total of 51 leaflets were evaluated (88% surgical tissue valves) after excluding leaflets not visible on CT (n = 5). On postprocedural CT, complete TCO was observed in 25.4% (13 of 51 leaflets). On preprocedural CT, leaflets were at high risk for complete TCO (incidence 53%) if the virtual THV-to-coronary distance (VTC) was <3.0 mm, or if the virtual THV-to-STJ distance (VTSTJ) was <1.0 mm with STJ height - leaflet length <0 mm (leaflet-STJ mismatch). Leaflets were at low risk (incidence 0%) if the VTC was ≥3 mm and VTSTJ was ≥3.0 mm or STJ height - leaflet length was ≥+2.0 mm. Of 28 leaflets treated using BASILICA, complete TCO was seen in 35.7% (n = 10), due to sinus sequestration (100%) with coexisting ostial obstruction (30%). Actual coronary events occurred in 7.1% (n = 2) because of leaflet prolapse, corresponding to an absolute risk reduction by BASILICA of 29% (P = 0.021).Risk assessment of coronary obstruction after TAVR may improve with a multiparametric approach incorporating VTC, VTSTJ, and leaflet-STJ mismatch. BASILICA appeared to reduce actual coronary events even in leaflets with anticipated coronary obstruction.

INTRACRANIAL EMBOLIZATION: A RARE COMPLICATION

We report a case of a rare complication: aortic pseudoaneurysm rupture after embolization of an intracranial aneurysm in a 62 –year- old patient with spontaneous subarachnoid hemorrhage, presented with chest pain and shortness of breath the fourth day after the procedure. The intracranial aneurysm was embolized with no intraoperative complications, and a postprocedural CT (computed tomography) scan showed no signs of intracranial rebleeding, ischemic lesions, or hydrocephalus. Cardiosurgical treatment was not indicated for the aortic pseudoaneurysm rupture.

Weakening or Structural Strengthening? An Evaluation of Bone Density after MRgFUS Ablation for Treatment of Benign Bone Lesions.

Previous studies suggest that interventional ablative procedures on bone lesions may weaken the bone, especially when performed through the needle approach. Our purpose was to evaluate, through Computed Tomography (CT), the effects of Magnetic Resonance guided Focused Ultrasound Surgery (MRgFUS) ablation on painful osteoid osteomas and osteoblastomas in terms of bone density and morphological changes. We retrospectively evaluated patients treated at our institution with MRgFUS for superficial, painful osteoid osteoma or osteoblastoma during the last 9 years. Inclusion criteria were procedural and clinical success, as well as the availability of pre- and postprocedural CT examinations. Imaging features assessed were perilesional/nidus density changes and the occurrence of pathological fractures during the follow-up period. Our study population included 31 osteoid osteomas and 5 intra-articular osteoblastomas in 36 treated patients. We found an increased bone density of the lesions when pre and post-treatment CT- values were compared: these differences were statistically significant, and this finding is consistent with significant bone densification at the post-treatment imaging follow-up. No pathological fractures were observed after ablation during the follow-up. MRgFUS can be considered to be the treatment of choice for benign superficial bone lesions, thanks to its minimal invasiveness, excellent effectiveness, and safety. Pathological fractures, reported in literature as a rare event using needle ablation, never occurred in our MRgFUS treatment series.

Abstract 12848: Patient-Specific in silico Models Demonstrate Hemodynamic Effect of LAMPOON in Transcatheter Mitral Valve Replacement

Introduction: The purpose of this study was to investigate the hemodynamic impact of LAMPOON (Laceration of the Anterior Mitral leaflet to Prevent Outflow ObstructioN) in transcatheter mitral valve replacement (TMVR) using patient-specific in silico modeling. Methods: Eight subjects from the LAMPOON investigational device exemption trial were included. All subjects were at prohibitive risk of outflow tract obstruction from TMVR based on computed tomography (CT), and underwent successful LAMPOON immediately followed by TMVR. A validated computational fluid dynamics (CFD) model was used to compare simulated hemodynamics and 3D flow patterns between two modeled conditions: 1) TMVR with LAMPOON and 2) TMVR without LAMPOON. Using the post-procedure CT scans, anatomical models of TMVR with LAMPOON were created for each subject. The open transcatheter valve cells were then virtually closed to model TMVR without LAMPOON for each subject. Finally, CFD was performed for each condition to simulate the systolic flow fields. Results: As compared to TMVR without LAMPOON, TMVR with LAMPOON resulted in lower peak velocity, lower peak LVOT gradient, and higher peak LVOT effective orifice area by 13 ± 6% (p=0.004), 28 ± 14% (p=0.008), and 15 ± 8% (p=0.002), respectively. LAMPOON provided flow communication through exposed cells of the transcatheter valve, thereby decreasing the flow constriction and reducing flow stasis in the vicinity of the neo-LVOT (Figure). The hemodynamic benefit of LAMPOON was observed to be greater in subjects with a smaller neo-LVOT area measured post-implant (p&lt;0.001). Conclusions: In silico modeling allowed for a quantitative patient-specific comparison of TMVR with and without LAMPOON, which is impossible to study clinically. The LAMPOON procedure improved simulated hemodynamics in all subjects, with a greater hemodynamic impact observed in subjects with a smaller post-implant neo-LVOT area.

Iterative Metal Artifact Reduction (iMAR) of the Non-adhesive Liquid Embolic Agent Onyx in Computed Tomography

BackgroundA drawback of Onyx, one of the most used embolic agents for endovascular embolization of intracranial arteriovenous malformations (AVM), is the generation of imaging artifacts (IA) in computed tomography (CT). Since these artifacts can represent an obstacle for the detection of periprocedural bleeding, this study investigated the effect of artifact reduction by an iterative metal artifact reduction (iMAR) software in CT in a brain phantom.MethodsTwo different in vitro models with two-dimensional tube and three-dimensional AVM-like configuration were filled with Onyx 18. The models were inserted into a brain imaging phantom and images with (n = 5) and without (n = 10) an experimental hemorrhage adjacent were acquired. Afterwards, the iMAR algorithm was applied for artifact reduction. The IAs of the original and the post-processed images were graded quantitatively and qualitatively. Moreover, qualitative definition of the experimental hemorrhage was investigated.ResultsComparing the IAs of the original and the post-processed CT images, quantitative and qualitative analysis showed a lower degree of IAs in the post-processed images, i.e. quantitative analysis: 2D tube model: 23.92 ± 8.02 Hounsfield units (HU; no iMAR; mean ± standard deviation) vs. 5.93 ± 0.43 HU (with iMAR; p < 0.001); qualitative analysis: 3D AVM model: 4.93 ± 0.18 vs. 3.40 ± 0.48 (p < 0.001). Furthermore, definition of the experimental hemorrhage was better in the post-processed images of both in vitro models (2D tube model: p = 0.004; 3D AVM model: p = 0.002).ConclusionThe iMAR algorithm can significantly reduce the IAs evoked by Onyx 18 in CT. Applying iMAR could thus improve the accuracy of postprocedural CT imaging after embolization with Onyx in clinical practice.

Augmented Reality for Retrosigmoid Craniotomy Planning.

While medical imaging data have traditionally been viewed on two-dimensional (2D) displays, augmented reality (AR) allows physicians to project the medical imaging data on patient's bodies to locate important anatomy. We present a surgical AR application to plan the retrosigmoid craniotomy, a standard approach to access the posterior fossa and the internal auditory canal. As a simple and accurate alternative to surface landmarks and conventional surgical navigation systems, our AR application augments the surgeon's vision to guide the optimal location of cortical bone removal. In this work, two surgeons performed a retrosigmoid approach 14 times on eight cadaver heads. In each case, the surgeon manually aligned a computed tomography (CT)-derived virtual rendering of the sigmoid sinus on the real cadaveric heads using a see-through AR display, allowing the surgeon to plan and perform the craniotomy accordingly. Postprocedure CT scans were acquired to assess the accuracy of the retrosigmoid craniotomies with respect to their intended location relative to the dural sinuses. The two surgeons had a mean margin of d avg = 0.6 ± 4.7 mm and d avg = 3.7 ± 2.3 mm between the osteotomy border and the dural sinuses over all their cases, respectively, and only positive margins for 12 of the 14 cases. The intended surgical approach to the internal auditory canal was successfully achieved in all cases using the proposed method, and the relatively small and consistent margins suggest that our system has the potential to be a valuable tool to facilitate planning a variety of similar skull-base procedures.