Computed Tomography Angiography Data Research Articles

Surgical Management of Posterior Communicating Artery Aneurysms in the Presence of a Low-Coursing Internal Carotid Artery and Narrowed Retrocarotid Window

Anatomical variations of the course of the internal carotid artery (ICA) may complicate surgical clipping of posterior communicating artery (PCoA) aneurysms by narrowing the retrocarotid window. We evaluated the efficacy of the periclinoid surgical maneuvers for expanding the retrocarotid window and analyzed computed tomography angiography (CTA) data from patients with PCoA aneurysms to define parameters for low-coursing ICAs. Using cadaveric specimens, standard pterional craniotomies were fashioned and extradural or intradural periclinoid surgical maneuvers-cutting of the meningo-orbital band, anterior clinoidectomy, and cutting of the distal dural ring (DDR)-were performed, and their relative advantages for expanding the retrocarotid window were assessed. Additionally, preoperative CTA data from 24 patients with PCoA aneurysms used to calculate the angles of the ICA relative to the skull base. Periclinoid maneuvers, especially the anterior clinoidectomy, provided additional exposure of the retrocarotid space. Cutting of the DDR allowed for partial mobilization of the ICA and widened the retrocarotid surgical window, enhancing maneuverability. The anterior clinoidectomy with cutting of the DDR allowed for enhanced exposure of the medial, middle, and posterolateral aspects of the retrocarotid space. Cutting the anterior petroclinoid fold and mobilizing cranial nerve III provided wide exposure of the lateral aspect of retrocarotid space. When clipping PCoA aneurysms in the presence of normal-coursing ICAs (approximately ≥30° ICA angle), a standard pterional craniotomy with anterior clinoidectomy and cutting of the DDR allows for substantial expansion of the retrocarotid window.

Combined assessment of subtended myocardial volume and myocardial blood flow for diagnosis of obstructive coronary artery disease using cardiac computed tomography: A feasibility study

BackgroundThis study aimed to evaluate the combined diagnostic performance of coronary artery stenosis-subtended myocardial volume (Vsub) and myocardial blood flow (MBFsub) on computed tomography (CT) for detecting obstructive coronary artery disease (CAD) assessed by invasive coronary angiography (ICA) and fractional flow reserve (FFR). MethodsThirty-nine patients who underwent coronary CT angiography (CTA) and stress dynamic myocardial CT perfusion (CTP) prior to ICA were enrolled. Obstructive CAD was defined as severe (≥70%) or moderate (30–69%) stenosis with FFR ≤0.8 on ICA. The Vsub was semi-automatically calculated from coronary CTA data using Voronoi diagram-based myocardial segmentation. The standard CT-MBF based on the 17-segment model was calculated using dynamic stress CTP data and deconvolution analysis. The CT-MBFsub was automatically analyzed by integrating the CT-MBF and Voronoi diagram-based myocardial segmentation analyses. The diagnostic performance of combined CT-MBFsub and Vsub assessment was determined using receiver operating characteristic analysis and compared with standard CT-MBF and CT-MBFsub. ResultsOf 117 vessels in 39 patients, 72 vessels were suspected of significant stenosis on CTA and 33 vessels had obstructive CAD on ICA and FFR. The sensitivity and specificity for identifying obstructive CAD were 67% and 82% for standard CT-MBF, 70% and 77% for CT-MBFsub, and 85% and 82% for combined CT-MBFsub and Vsub assessment. The area under the receiver operating characteristic curve of the combined CT-MBFsub and Vsub assessment was significantly higher than those of standard CT-MBF and CT-MBFsub (0.89 vs. 0.75, 0.77; p<0.05). ConclusionsThe Vsub may aid in increasing the diagnostic performance of CT-MBFsub for detecting obstructive CAD.

Non-invasive fractional flow reserve: a comparison of one-dimensional and three-dimensional mathematical modeling effectiveness

Aim. Comparative analysis of the diagnostic effectiveness of onedimensional (1-D) and three-dimensional (3-D) non-invasive methods for coronary fractional flow reserve (FFR) assessment based on the coronary computed tomography angiography (CCTA). Material and methods . We carried out a retrospective analysis of CCTA data for 13 patients (men — 9, mean age — 61,07±9,73). In the original research, coronary FFR of those patients was evaluated using the original 3-D HeartFlow® Analysis followed by a standard invasive FFR assessment. We estimated coronary FFR using the 1-D algorithm of the Laboratory of Mathematical Modeling (Sechenov University) and compared the diagnostic effectiveness of these methods. Results. In per-vessel analysis, the sensitivity and specificity of the 3-D approach were 90,91% (95% confidence interval (CI) 62,26-99,53) and 20% (95% CI 0,01026-62,46, p>0,9999), respectively; in per-patient analysis — 90% (95% CI 59,58-99,49) and 0% (95% CI 0-56,15, p>0,9999), respectively; area under the ROC curve was 93,75% (95% CI 80,26-100), p=2,0431e-10. For the 1-D approach, the same parameters in per-patient analysis were 88,89 % (95% CI 56,50-99,43) and 25% (95% CI 0,01282-69,94, p>0,9999), respectively; in per-vessel analysis — 100% (95% CI 72,25-100) and 33,33% (95% CI 0,05923-70, p=0,1250), respectively; area under the ROC curve was 84,54% (95% CI 63,93-100), p=0,001. Spearman’s rank correlation coefficient between the 3-D and 1-D techniques was 0,7326 (95% CI 0,35810,9041), p=0,0017. Conclusion. Although we have obtained lower values of area under the ROC curve, the sensitivity and specificity of experimental approach, as well as the correlation coefficient between models were rather high. However, further studies with higher statistical power are required.

Application of Computed Tomography Angiography Data Monitoring in Cerebral Glioma (Preprint)

Application of Computed Tomography Angiography Data Monitoring in Cerebral Glioma (Preprint)

Abstract QS36: Spatial Fidelity Of Microvascular Perforating Vessels As Perceived By Augmented Reality Holographic Projections

Purpose: Breast reconstruction using free-tissue transfer yields improved long-term aesthetic results as reported by patients, but requires increased resources of practitioners and hospital systems. Much of the complexity of microvascular reconstruction can be attributed to flap harvest, as dissection must account for anatomic variability, and is guided at best by ancillary imaging modalities which must be extrapolated to the patient on the table. Augmented reality affords the opportunity to superimpose relevant imaging on a surgeon’s native field of view. This potentially allows integration of imaging in real-time to better guide flap selection and facilitate dissection. We aimed to assess the spatial fidelity of key anatomic landmarks on augmented-reality projections compared to 3D printed anatomic simulacrum models formatted from CT-Angiography (CTA) imaging in patients undergoing autologous breast reconstruction. Methods: 3D-printed composite models of rectus abdominal muscles and associated Deep Inferior Epigastric Arteries (DIEP) with perforating vessels were fabricated from CTA data from de-identified patients. The corresponding CTA data was similarly formatted to be used on the Microsoft Hololens with the Microsoft Mixed Reality Toolkit 2.01 and Unity 2019.2.4 Visual Studio. Coordinates were measured using the OptiTrack Flex 13 Motion tracking system. The 3D printed models were zeroed to an arbitrary reference point maintained for each set specimen. Established anatomic points including upper and lower borders of the umbilicus, superficial location of perforating vessels, and corners of the model were initially measured. The Hololens projection was then superimposed using hand-gesture and voice commands onto the model, and set into place, ensuring immobile position despite translational movement of the headset. The model was then removed, and the corresponding anatomic reference points were recorded in triplicate from two separate vantages. Results: Five sets of 3D printed models and corresponding Hololens projections were measured. Absolute distance from left to right perforators were calculated from measurements of the model and the Hololens projection, from two vantages. Analysis of variance (ANOVA) were conducted on each group of measurements independently for each specimen. In two of the five specimens (#1 and #32), there was no significant difference in inter-perforator distance. The greatest discrepancy of inter-perforator distance between any projection and those measured on 3D models was 5.6 mm in specimen 21. Conclusions: Our data demonstrate that holographic projections can be used to accurately localize relevant three-dimensional structures extrapolated from CT imaging, on the scale of millimeters. Two of five models demonstrated no significant variability in perceived three-dimensional location of inter-perforator distance and, despite significant inter-group variability, Hololens projections were perceived within millimeters of the corresponding physical landmark. Augmented reality provides a potential paradigm shifting adjunct for intra-operative localization of perforating vessels in free-tissue flap harvest.

Visualization of Stereoscopic Model of the Liver and Gallbladder from Clinical Perspective

The hepatobiliary system is the most common site for many diseases, and anatomy of this region could be complicated. Laparoscopy surgery has now become the preferred option for cholecystectomy and many other gastrointestinal conditions. These procedures require advanced laparoscopic techniques and anatomical knowledge of the region. Understanding and familiarizing with the anatomical relationship of the liver and gallbladder will help clinicians in the evaluation and management of such diseases as gallbladder stones, bile duct stones, pancreatic duct stones, and liver cancers, etc. The development of 3D stereoscopic models usually requires the acquisition and conversion of voxel‐based CT or MRI data into 3D models. It has been reported recently that the computed tomography angiography (CTA) was used to create vascular models using volume rendering, and surface rendering for educational purpose. CTA images have been extensively used for vasculature anatomy, detection and evaluation of intracranial aneurysms, and diagnosis of ischemic stroke, however, the CTA data has not been well explored for creating a hepatobiliary and pancreatic stereoscopic virtual model in contemporary anatomy education. In this study, we utilize CTA data to develop a stereoscopic liver, gallbladder and pancreas model using the semi‐auto combined rendering in addition to the volume and surface rendering methods. The visualization of the liver, associated with other organs and their relationship can be viewed via the stereoscopic presentation. The two‐dimensional (2D) and 3D measurements can be applied to measure the length, angle, and volume of the liver. The stereoscopic visualization and comparison of the measurement might have potential benefit for helping students and clinicians to better understand anatomy knowledge in medical education and clinical training. The stereoscopic view of surgical field might as well enhance the surgeon’s dexterity.

Creating Computed Tomography Angiography Stereoscopic Models to Enhance the Learning of the Hepatobiliary Region

Current anatomical education continues to increase the use of three‐dimensional (3D) models rendered from radiographic imaging to assist student’s anatomical spatial awareness. Such orientation is valuable and clinically essential, especially when such knowledge is used in conjunction with diagnostic imaging modalities that can further guide treatment plans. Therefore, in programs that rely on cadaveric dissection, it is crucial to efficiently orient novice students to utilize imaging modalities early in their educational careers so that they can recognize any pathological or anomalous structures that other educational 3‐D resources may have limitations in displaying. Some 3‐D rendered models obtained from computed tomography angiography (CTA) have already been clinically derived to facilitate in orienting students to the intracranial neurovascular anatomy. However, there are a limited amount of CTA derived 3‐D models to aid in the study of other anatomical regions, in particular, the hepatobiliary region of the abdomen. In an effort to enhance the continued education of graduate and medical professional students, we have developed a 3D stereoscopic model rendered from CTA‐derived data that are consistent with the pancreatic hepatobiliary region with accompanying vasculature and associated gastrointestinal (GI) tract. Although 3‐D stereoscopic models usually use voxel‐based CTA data, our model uses semi‐auto combined rendering with complementary volume and surface rendering methods. Our ultimate goal is to utilize this virtual model presentation to help students clearly identify anatomical structures, both on cadaveric specimens and through imaging modalities. Future studies will consist of comparing students who are undertaking a gross anatomy course to students who are enrolled in the course but who also view the virtual 3D hepatobiliary model presentation to further support their anatomical education.

Clinical application of digital technology in repairing of heel wound with peroneal artery perforator propeller flap

To study the effectiveness of digital technique in repairing of heel wound with peroneal artery perforator propeller flap. Between March 2016 and March 2019, the heel wounds of 31 patients were repaired with the peroneal artery perforator propeller flaps. There were 21 males and 10 females, with an average age of 36 years (range, 12-53 years). Seventeen patients were admitted to hospital in emergency after trauma, the time from injury to admission was 6.0-12.5 hours, with an average of 8.5 hours; 14 patients were chronic infectious wounds and ulcer. The wound area ranged from 5 cm×4 cm to 12 cm×8 cm. Before flap repair, CT angiography (CTA) data of lower extremity was imported into Mimics19.0 software and three-dimensional reconstruction of peroneal artery perforator and skin model, accurate location of perforator, accurate design of perforator flap, and simulated operation according to the defect range and location were obtained. The origin and course of peroneal artery perforator, the position of perforator, the diameter of perforator, and the maximum length of the naked perforator were determined based on the three-dimensional model. There was no significant difference in locating point of perforator, diameter of perforator, maximum length of naked perforator between the pre- and intra-operative measurements ( P>0.05). The position of the lower perforator of the peroneal artery were on the posterolateral lateral ankle tip (5-10 cm) in 31 cases. The total incidence of perforating branches within 10 cm on the tip of lateral malleolus was 96.9%, and the length of vascular pedicle was (3.44±0.65) cm. The flap removal and transposition in 31 patients were successfully completed. The average operation time was 45 minutes (range, 30-65 minutes). After operation, vein crisis and partial necrosis occurred in 4 cases and 3 cases, respectively, which were survived after symptomatic treatment. All the grafts survived and the incisions healed by first intention. All the patients were followed up 3-18 months, with an average of 12 months. At last follow-up, according to the American Orthopaedic Foot and Ankle Society (AOFAS) score, 17 cases were excellent, 11 cases were good, and 3 cases were fair, and the excellent and good rate was 87.5%. The digital technique can improve the accuracy of perforator localization and the design of peroneal artery perforator propeller flap, and reduce the difficulty of operation, and the risk caused by the variation of vascular anatomy.

Critical appraisal of multidimensional CT measurements following acute open repair of type A aortic dissection.

IntroductionTo identify patients with aneurysmal degeneration of the native aorta following type A aortic dissection (TAAD), reproducible serial measurements of aortic dimensions are critical. We used a systematic workflow for measuring aortic geometry following TAAD, using computed tomography angiography data, and test its reproducibility.MethodsThe workflow for aortic measurements included centerline generation, luminal diameter, and area measurement at six anatomically defined locations along the aorta and luminal volumetric measurements in the descending aorta. Two independent observers measured the aortic geometry in 20 surgically repaired TAAD patients, preoperatively and at 3 months follow‐up. To test reproducibility, intraobserver and interobserver agreement scores were analyzed using a concordance correlation coefficient (CCC).ResultsThe interobserver agreement scores of the diameter, area, and volumetric measurements in the descending aorta were acceptable. The agreement scores of the area measurements were highest, with CCCs ranging from 0.909 to 0.984. Luminal diameter measurements scored lower than luminal area measurements and were least reproducible at the mid aortic arch (CCC < 0.886). Overall, intraobserver agreement scores were better than interobserver agreement scores (SD of mean difference was 1.89 vs 1.94 for intraobserver vs interobserver diameter measurements, and 0.61 vs 0.66 for area measurements).ConclusionAlthough overall reproducibility was acceptable in descending aortic measurements, our results show that it remains challenging to reliably measure luminal diameters, compared with areas. To aid identification of early adverse remodeling following acute TAAD, novel two‐ and three‐dimensional measurement techniques are needed that capture locoregional changes in the false lumen and true lumen morphology more accurately.

Automated Grading of Cerebral Vasospasm to Standardize Computed Tomography Angiography Examinations After Subarachnoid Hemorrhage.

Background: Computed tomography angiography (CTA) is frequently used with computed tomography perfusion imaging (CTP) to evaluate whether endovascular vasospasm treatment is indicated for subarachnoid hemorrhage patients with delayed cerebral ischemia. However, objective parameters for CTA evaluation are lacking. In this study, we used an automated, investigator-independent, digital method to detect vasospasm, and we evaluated whether the method could predict the need for subsequent endovascular vasospasm treatment.Methods: We retrospectively reviewed the charts and analyzed imaging data for 40 consecutive patients with subarachnoid hemorrhages. The cerebrovascular trees were digitally reconstructed from CTA data, and vessel volume and the length of the arteries of the circle of Willis and their peripheral branches were determined. Receiver operating characteristic curve analysis based on a comparison with digital subtraction angiographies was used to determine volumetric thresholds that indicated severe vasospasm for each vessel segment.Results: The automated threshold-based volumetric evaluation of CTA data was able to detect severe vasospasm with high sensitivity and negative predictive value for predicting cerebral hypoperfusion on CTP, although the specificity and positive predictive value were low. Combining the automated detection of vasospasm on CTA and cerebral hypoperfusion on CTP was superior to CTP or CTA alone in predicting endovascular vasospasm treatment within 24 h after the examination.Conclusions: This digital volumetric analysis of the cerebrovascular tree allowed the objective, investigator-independent detection and quantification of vasospasms. This method could be used to standardize diagnostics and the selection of subarachnoid hemorrhage patients with delayed cerebral ischemia for endovascular diagnostics and possible interventions.

Predicting the Feasibility of Utilizing SIEA Flap for Breast Reconstruction with Preoperative BMI and Computed Tomography Angiography (CTA) Data.

Diameters greater than 1.5mm are considered one of the generally accepted criteria for utilizing superficial epigastric artery (SIEA) flaps for breast reconstruction. However, this standard fails to consider individual differences among patients or deep inferior epigastric perforator (DIEP) perfusion of the same angiosome as the SIEA. This study combined the SIEA system with the DIEP system and explored the relationship between the two systems and body mass index (BMI) to theoretically provide a reference for flap choice in the preoperative surgical plan. This study analysed preoperative computed tomography angiography (CTA) data from patients who received systematically postoperative treatment for unilateral breast cancer and were scheduled for breast reconstruction from 2013 to 2018 in our centre. All patients included had no past medical history that might have influenced the diameter of the SIEA, and their CTA data showed the presence of SIEA. Twenty-five females with a mean BMI of 23.6 ± 3.3kg/m2 were included. A total of 30 hemi-abdomens identified with the SIEA were assessed. The measured mean diameter of the SIEA was 1.63 ± 0.55mm, showing a highly linear correlation with BMI (r = 0.73, p < 0.001), while the maximum diameter of the deep inferior epigastric perforator (DIEPmax) and the number of dominant perforators originating from the deep inferior epigastric artery (DIEA) were not related to BMI. It was analysed from the equation between the calibre of the SIEA and BMI that when the BMI was greater than or equal to 24kg/m2, the minimum diameter of the SIEA was at least 1.5mm; when the BMI was 25kg/m2, the diameter of the SIEA was, at most, 2.0mm. Based on the linear correlation described above, we proposed that if the diameter of the SIEA was greater than or equal to 2.0mm, a BMI ≥ 25kg/m2 could be fully guaranteed. In terms of the advantageous single pedicle for reconstruction, the ratio of the SIEA diameter to DIEPmax (SIEA/DIEPmax) showed a significant linear correlation with BMI (r = 0.82, p < 0.001), and when the BMI was greater than or equal to 25kg/m2, the lower limit of its predicted value was above 1.0; in other words, the SIEA diameter was advantageous compared with DIEPmax for the use of a single pedicle. In terms of perfusion, the SIEA system was positively correlated with BMI (p < 0.001), while the DIEP system was not. The difference in perfusion level between the SIEA and DIEP systems showed a positive correlation with BMI (p = 0.001), while the sum of the two systems only tended to be correlated, without statistical significance (p = 0.06). For patients with a BMI ≥ 25kg/m2 or an SIEA diameter ≥ 2.0mm, application of an SIEA flap is theoretically a preferable choice in preoperative surgical planning for breast reconstruction. And the patients should meet two conditions: the first one is the absence of past medical history that might potentially influence the diameter of the SIEA; the second is the presence of the SIEA, which has already been shown by the preoperative imaging data. Through perfusion-related studies, we propose that the SIEA is likely a compensatory vessel that is inclined to present in people with larger BMIs. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Analysis of local hemodynamics in complex aneurysms: an effect of the vessel arising from the dome or the neck

Assessment of rupture risk for intracranial aneurysms (IA) is a particular challenge in cases of so-called complex aneurysms due to their variable morphometric characteristics. Arterial branch arising from the dome or the neck of IA is one of the least explored features of complex aneurysms. The methods of computational fluid dynamics may be valuable to determine the influence of arterial branches of IA on local hemodynamics. To analyze local hemodynamics in IA with arterial branch arising from the cupola or the neck depending on the structure of the aneurysm and blood flow rate in the parent vessel. CT angiography data of 4 patients with IA were estimated in this study. Modifications of the baseline 3D models of the aneurysms resulted 12 patient-specific models included into analysis. Hemodynamic calculations were made by using of ANSYS Workbench 19 software package. Wall shear stress (WSS) was characterized by the most significant variability, especially in case of sidewall aneurysms. Small cross-sectional area of additional branch in relation to the neck of IA was not followed by considerable changes of blood flow patterns inside IA after «virtual» removal of the vessel. Otherwise, the intensity of flows was drastically reduced. Simulation of high inlet flows demonstrated substantial variation of WSS in the area of jet. Additional arterial branch arising from the dome or the neck of IA significantly influences local hemodynamics. This influence depends on the localization of IA in relation to the parent vessel and the diameter of additional arterial branch.

Reference values for mid-diastolic right ventricular volume in population referred for cardiac computed tomography: An additional diagnostic value to cardiac computed tomography

BackgroundWhile an assessment of the right ventricular (RV) size remains challenging, the entire RV is can be imaged on coronary computed tomography angiography (CCTA) studies. With prospective ECG-triggering, the RV end diastolic volume (RVEDV) cannot be measured; however, the RV mid-diastolic volume (RVMDV) can still be measured accurately from routine CCTA data sets. The objective of this study is to establish normal reference values for RVMDV. MethodsRight ventricular mid-diastolic volumes were measured in 4855 consecutive patients undergoing prospectively ECG-triggered coronary CTA. All patients with known cardiac or pulmonary disease (coronary artery disease, myocardial infarction, revascularization, heart failure, pulmonary hypertension, congenital heart disease, valvular heart disease, atrial fibrillation, implantable cardiac defibrillator implantation, cardiac transplant, or cardiac surgery) or smoking history (3313 patients) were excluded. Results1542 patients were analyzed (mean age 56.4 ± 11.1 years, mean BSA 1.96 ± 0.26 and 47% male). The mean RVMDV for men and women was 168.6 ± 37.6 mL and 117.6 ± 26.4 mL, respectively. Mean BSA-indexed RVMDV was 80.0 ± 15.3 mL/m2 and 64.1 ± 12.2 mL/m2 for men and women, respectively. The presence of hypertension and diabetes did not have an impact on these values. RVMDV and BSA-indexed RVMDV were lower in women and in older individuals. ConclusionNormal reference ranges for RVMDV were established using prospectively ECG-triggered coronary CTA studies. This data can be used to identify patients with abnormal RV volumes and potentially RV dysfunction, adding incremental diagnostic value to routine CCTA studies.

Evaluation of non-ECG and ECG-gated computed tomographic angiography for three-dimensional printing of anomalous coronary arteries in dogs with pulmonic stenosis

Introduction/objectivesCoronary artery abnormalities are described sporadically in dogs, most commonly with pulmonic stenosis. Computed tomographic angiography (CTA) allows non-invasive assessment of coronary anatomy. Three-dimensional (3D) models improve the understanding and visualization of spatially complex anatomy. The study objective was to evaluate coronary artery anomalies using CTA imaging and using rapid prototyping technology to create life-sized coronary artery models of these studies. Animals, material and methodsCombined retrospective case and prospective pilot study. Inclusion criteria were dogs with reported coronary artery anomalies. The CTA data sets were imported into a medical imaging framework for the analysis of the coronary arteries and into a 3D-planning and printing software for creating printable 3D models. The 3D models were printed using fusion deposition modeling technology. ResultsSix male dogs with an R2A coronary artery anomaly and pulmonic stenosis diagnosed by CTA were included. Electrocardiogram (ECG)-gated CTA allowed better identification of anomalous coronary arteries than non-gated CTA. In all dogs, the right coronary artery had a smaller diameter than the left and the left coronary artery or its branch had a prepulmonic course. All ECG-gated studies were 3D printed while non-gated studies were not printable due to CTA artifacts. ConclusionIn dogs, CTA is effective for diagnosis of coronary artery anomalies. Printed 3D models of ECG-gated CTA studies were of excellent quality and allowed direct visualization of abnormal coronary artery anatomy. The usefulness of these models to improve the understanding of anomalous coronary artery anatomy could be evaluated in future studies.

Image-Guided Transcranial Doppler Ultrasound for Monitoring Posthemorrhagic Vasospasms of Infratentorial Arteries: A Feasibility Study

A considerable number of patients with subarachnoid hemorrhage (SAH) develop vasospasms of the infratentorial arteries. Transcranial Doppler sonography (TCD) is used to screen for vasospasm. In this study, we used a technical modification that combines TCD with an image guidance device that the operator can use to navigate to the ultrasonic window and to predefined intracranial vascular targets. Our aim was to analyze the feasibility, spatial precision, and spatial reproducibility of serial image-guided TCD of infratentorial and-for comparison-supratentorial arteries in the clinical setting of monitoring for vasospasm after SAH. The study included 10 SAH patients, who each received 5 serial image-guided TCD examinations. Using computed tomography angiography data, trajectories to the infratentorial and supratentorial cerebral arteries were planned and loaded into an image guidance device tracking the Doppler probe. As a measure of spatial precision and spatial reproducibility, we analyzed the distances between the positions of preplanned vascular targets and optimal Doppler signals. The mean distance between preplanned and optimal target points was 4.8 ± 2.1 mm (first exam), indicating high spatial precision. The spatial precision decreased with increasing depth of the vascular target. In all patients, image-guided TCD detected all predefined supratentorial and infratentorial vascular segments. There were no significant changes in spatial precision in serial exams, indicating high reproducibility. Image-guided TCD is feasible for supratentorial and infratentorial arteries. It shows high spatial precision and reproducibility. This study provides a basis for future clinical studies on image-guided TCD for post-SAH vasospasm screening.

Risk factors of distal segment aortic enlargement after complicated type B aortic dissection

ObjectivesDistal segment aortic enlargement (DSAE) is a common complication that influences the long-term prognosis of type B aortic dissection (TBAD) after thoracic endovascular aortic repair (TEVAR). In this study, a multivariate analysis was performed to find potential factors predictive of DSAE. MethodsA single-center retrospective study was performed from 1999 to 2016. Included in the study were complicated TBAD patients who underwent TEVAR with uncovered residual tears. Based on the diameter of the distal segment of the uncovered aorta, we assigned patients to an enlargement group and a non-enlargement group. Data extracted from the medical records included demographic and clinical characteristics and follow-up computed tomography angiography data. The primary endpoints were the all-cause mortality and the presumably aortic-related events that required reintervention during the follow-up period. ResultsFor the 333 patients, all-cause mortality was 38 (11.41%), and 76 (22.82%) patients underwent reintervention. A total of 70 (21.02%) patients experienced DSAE, among them were 2 patients who died of aortic rupture and 58 patients who accepted reintervention. Multivariate analysis reviewed independent risk factors of postoperative DSAE, including current smoking, the residual length of the patent false lumen, the postoperative number of dissection tears in the thoracic aorta and type III aortic arch; as well as protective factors, including the application of a restrictive bare stent (RBS), the length of covered stent in the descending thoracic aorta, and the distance from the residual first tear to the left subclavian artery (LSA). ConclusionDSAE after TEVAR for patients with a complicated TBAD can be influenced by their current smoking habit, the residual length of patent false lumen, the postoperative number of dissection tears in the thoracic aorta and the aortic arch type. Meanwhile, RBS usage, the length of the covered stent in the descending thoracic aorta and the distance from the residual first tear to the LSA could have positive effect on the prognosis.

Coronary artery stenosis-related perfusion ratio using dynamic computed tomography myocardial perfusion imaging: a pilot for identification of hemodynamically significant coronary artery disease

The purpose of this study was to evaluate the feasibility of the stenosis-related quantitative perfusion ratio (QPR) for detecting hemodynamically significant coronary artery disease (CAD). Twenty-seven patients were retrospectively enrolled. All patients underwent dynamic myocardial computed tomography perfusion (CTP) and coronary computed tomography angiography (CTA) before invasive coronary angiography (ICA) measuring the fractional flow reserve (FFR). Coronary lesions with FFR ≤ 0.8 were defined as hemodynamically significant CAD. The myocardial blood flow (MBF) was calculated using dynamic CTP data, and CT-QPR was calculated as the CT-MBF relative to the reference CT-MBF. The stenosis-related CT-MBF and QPR were calculated using Voronoi diagram-based myocardial segmentation from coronary CTA data. The relationships between FFR and stenosis-related CT-MBF or QPR and the diagnostic performance of the stenosis-related CT-MBF and QPR were evaluated. Of 81 vessels, FFR was measured in 39 vessels, and 20 vessels (51%) in 15 patients were diagnosed as hemodynamically significant CAD. The stenosis-related CT-QPR showed better correlation (r = 0.70, p < 0.05) than CT-MBF (r = 0.56, p < 0.05). Sensitivity and specificity for detecting hemodynamically significant CAD were 95% and 58% for CT-MBF, and 95% and 90% for CT-QPR, respectively. The area under the receiver operating characteristic curve for the CT-QPR was significantly higher than that for the CT-MBF (0.94 vs. 0.79; p < 0.05). The stenosis-related CT-QPR derived from dynamic myocardial CTP and coronary CTA showed a better correlation with FFR and a higher diagnostic performance for detecting hemodynamically significant CAD than the stenosis-related CT-MBF.

Performance of a Deep Neural Network Algorithm Based on a Small Medical Image Dataset: Incremental Impact of 3D-to-2D Reformation Combined with Novel Data Augmentation, Photometric Conversion, or Transfer Learning.

Collecting and curating large medical-image datasets for deep neural network (DNN) algorithm development is typically difficult and resource-intensive. While transfer learning (TL) decreases reliance on large data collections, current TL implementations are tailored to two-dimensional (2D) datasets, limiting applicability to volumetric imaging (e.g., computed tomography). Targeting performance enhancement of a DNN algorithm based on a small image dataset, we assessed incremental impact of 3D-to-2D projection methods, one supporting novel data augmentation (DA); photometric grayscale-to-color conversion (GCC); and/or TL on training of an algorithm from a small coronary computed tomography angiography (CCTA) dataset (200 examinations, 50% with atherosclerosis and 50% atherosclerosis-free) producing 245 diseased and 1127 normal coronary arteries/branches. Volumetric CCTA data was converted to a 2D format creating both an Aggregate Projection View (APV) and a Mosaic Projection View (MPV), supporting DA per vessel; both grayscale and color-mapped versions of each view were also obtained. Training was performed both without and with TL, and algorithm performance of all permutations was compared using area under the receiver operating characteristics curve. Without TL, APV performance was 0.74 and 0.87 on grayscale and color images, respectively, compared to 0.90 and 0.87 for MPV. With TL, APV performance was 0.78 and 0.88 on grayscale and color images, respectively, compared with 0.93 and 0.91 for MPV. In conclusion, TL enhances performance of a DNN algorithm from a small volumetric dataset after proposed 3D-to-2D reformatting, but additive gain is achieved with application of either GCC to APV or the proposed novel MPV technique for DA.

Short-term results of bilateral internal mammary arterial grafting for patients aged 60\u201375 years \u2013 a retrospective study

BackgroundBilateral internal mammary artery (BIMA) grafting has a good long-term survival rate and graft patency rate, but it is only recommended in young patients due to its high technical requirements and high incidence of sternal complications. Previous studies indicated that BIMA grafting has a significant benefit in patients aged 50–59 years, but this benefit does not extend to patients aged > 60 years. Thus, this study was designed to analyse the immediate artery graft function, short-term (3 months) results, and experience in preventing sternal complications for BIMA grafting in elderly patients (60–75 years old).MethodsClinical records and echocardiographic and coronary artery computed tomography angiography data of 155 patients who underwent BIMA grafting for coronary artery disease between 2015 and 2017 in our hospital were analysed retrospectively to summarise the operative experience and short-term (3 months) results. Patients were divided into two groups: Group A (n = 95), aged < 60 years and Group B (n = 60), aged 60–75 years. The operation time, aortic clamp time, and cardiopulmonary bypass time of these two groups were compared to analyse the operation difficulty and the flow and pulsatility index were compared to analyse the immediate artery graft function. The left ventricular end-diastolic dimension (LVEDD) and left ventricular ejection fraction (LVEF) of these two groups were compared to analyse heart function.ResultsThere were no significant differences in the operation time, aortic clamp time, and cardiopulmonary bypass time as well as the flow and pulsatility index between these two groups (P > 0.05). There was no significant difference in the incidence of sternal wound complications, graft occlusion, and other common complications 3 months post-BIMA grafting between these two groups (P > 0.05). Furthermore, there was no significant difference in LVEDD and LVEF between the groups 3 months post-operation (P > 0.05).ConclusionsBIMA grafting was safe and effective for older patients (60–75 years). Similar to younger patients (< 60 years), BIMA grafting in elderly patients (60–75 years) can also achieve a satisfactory short-term (3 months) result. Thus, advanced age (60–75 years) should not be a contraindication for BIMA grafting.

P6175Prediction of coronary revascularization by coronary computed tomography angiography derived fractional flow reserve - different algorithms for interpretation

Abstract Introduction Coronary CT angiography (CTA) derived fractional flow reserve (FFRct) is increasingly used for guiding referral to invasive procedures in patients with stable chest pain. However, optimal interpretation of FFRct-analysis in terms of location and threshold of applied FFRct-values is unclear. Purpose To evaluate the clinical performance of various vessel-specific physiological FFRct derived measures of ischemia for prediction of standard of care guided coronary revascularization in patients with stable chest pain and coronary artery disease as determined by coronary CTA. Methods Retrospective study in patients with stable chest pain referred for coronary angiography based on coronary CTA. Standard acquired coronary CTA data sets were transmitted for core-laboratory analysis at HeartFlow. Any FFRct value in the major coronary arteries ≥1.8 mm in diameter, including side branches, were registered. Lesions were categorized as positive for ischemia using 6 different algorithms: Lowest in vessel FFRct-value (1) ≤0.75 or (2) ≤0.80; 2 cm distal-to-lesion FFRct-value (3) ≤0.75 or (4) ≤0.80; ΔFFRct (5) ≥0.06 or a combination of 2 and 5. The personnel responsible for downstream patient management had no information regarding FFRct test results. Results A total of 172 patients were included. Revascularization was performed in 62 (35%) patients. The diagnostic performance of different FFRct algorithms for predicting standard of care guided coronary revascularization is shown in the Table. Revascularization Predictions by FFRct N=172 Diagnostic performance FFRCT false negative FFRCT false positive Values given as (%) No. of revasc vessels No. of abnormal vessels FFRCT Algorithm Sens Spec PPV NPV Acc 1 2 3 1 2 3 Distal FFRCT ≤0.75 77 68 58 84 72 12 2 0 29 5 1 Distal FFRCT ≤0.80 92 43 48 90 61 5 0 0 40 20 3 Lesion-specific FFRCT ≤0.75 68 86 74 83 80 17 3 0 12 3 0 Lesion-specific FFRCT ≤0.80 82 78 68 89 80 10 2 0 21 3 1 ΔFFRCT ≥0.06 98 36 47 98 59 1 0 0 51 19 0 Combinationa 92 54 53 92 67 5 0 0 39 12 0 aDistal FFRCT ≤0.80 and ΔFFRCT ≥0.06. Sens = sensitivity; Spec = specificity; PPV = positive predictive value; NPV = negative predictive value; Acc = accuracy; FFRCT = fractional flow reserve derived from coronary CTA; ΔFFRCT = difference between FFRCT-value immediately proximal and distal to lesion; Revasc = revascularized. Conclusion The diagnostic performance of FFRct in terms of predicting standard of care guided coronary revascularization is dependent on the applied algorithm for interpretation of the FFRct-analysis.