Angiography Reconstruction Research Articles

Implications of computed tomography reconstruction algorithms on coronary atheroma quantification: Comparison with intravascular ultrasound

BackgroundAdvances in coronary computed tomography angiography (CCTA) reconstruction algorithms are expected to enhance the accuracy of CCTA plaque quantification. We aim to evaluate different CCTA reconstruction approaches in assessing vessel characteristics in coronary atheroma using intravascular ultrasound (IVUS) as the reference standard. MethodsMatched cross-sections (n ​= ​7241) from 50 vessels in 15 participants with chronic coronary syndrome who prospectively underwent CCTA and 3-vessel near-infrared spectroscopy-IVUS were included. Twelve CCTA datasets per patient were reconstructed using two different kernels, two slice thicknesses (0.75 ​mm and 0.50 ​mm) and three different strengths of advanced model-based iterative reconstruction (IR) algorithms. Lumen and vessel wall borders were manually annotated in every IVUS and CCTA cross-section which were co-registered using dedicated software. Image quality was sub-optimal in the reconstructions with a sharper kernel, so these were excluded. Intraclass correlation coefficient (ICC) and repeatability coefficient (RC) were used to compare the estimations of the 6 CT reconstruction approaches with those derived by IVUS. ResultsSegment-level analysis showed good agreement between CCTA and IVUS for assessing atheroma volume with approach 0.50/5 (slice thickness 0.50 ​mm and highest strength 5 ADMIRE IR) being the best (total atheroma volume ICC: 0.91, RC: 0.67, p ​< ​0.001 and percentage atheroma volume ICC: 0.64, RC: 14.06, p ​< ​0.001). At lesion-level, there was no difference between the CCTA reconstructions for detecting plaques (accuracy range: 0.64–0.67; p ​= ​0.23); however, approach 0.50/5 was superior in assessing IVUS-derived lesion characteristics associated with plaque vulnerability (minimum lumen area ICC: 0.64, RC: 1.31, p ​< ​0.001 and plaque burden ICC: 0.45, RC: 32.0, p ​< ​0.001). ConclusionCCTA reconstruction with thinner slice thickness, smooth kernel and highest strength advanced IR enabled more accurate quantification of the lumen and plaque at a segment-, and lesion-level analysis in coronary atheroma when validated against intravascular ultrasound. Clinicaltrials.gov (NCT03556644)

Double Aortic Arch as a Rare Condition in a 10-year-old Boy with Recurrent Pneumonia: A Case Report Study

Introduction: A double aortic arch (DAA) is a congenital anomaly of the aortic arch, which is also the most common type of complete vascular ring. This vascular ring can compress the trachea and esophagus, as well as cause respiratory, gastrointestinal, and cardiac symptoms. Case Presentation: In the present case report, a 10-year-old boy with recurrent cough, fever, shortness of breath, chest pain, and a history of recurrent respiratory infections was examined. According to the results of bronchoscopic evaluation, he was found to have a localized tracheomalacia. DAA and dextrocardia condition were also confirmed for this patient by performing a computed tomography angiography of the thorax and the three-dimensional reconstruction of CT angiography. Conclusions: The diagnosis of double aortic arch may be confused with upper respiratory tract infections or foreign body aspiration. Therefore, it was recommended that a particular attention should be paid to the double aortic arch when evaluating cases of stridor in children with unknown causes or recurrent respiratory infections. CT angiography and cardiac MRI were the diagnostic methods of choice for examining vascular rings.

Computed Tomography Angiography and Three-Dimensional Reconstruction of Renal Arteries in Diagnosing the Bleedings After Mini-Percutaneous Nephrolithotomy: A Single-center Experience of 7 Years

ObjectiveThis study aimed to investigate the role of computed tomography angiography (CTA) and three-dimensional (3D) reconstruction of renal arteries in the evaluation of bleeding after mini- percutaneous nephrolithotomy (PCNL). MethodsThirty-one consecutive patients with continuous renal hemorrhage after mini-PCNL were enrolled from January 2015 to January 2022. Demographic and clinical data were retrospectively recorded and analyzed. All patients had received CTA evaluation and subsequently digital subtraction angiography (DSA) embolization to manage renal bleeding. CTA and 3D reconstruction of renal arteries were performed using the 320 multi-detector computed tomography technique and the images were evaluated by experienced radiologists. DSA embolization were performed by an interventional radiologist with more than 10 years of experiences. ResultsCTA and 3D construction of renal arteries showed 28 cases of vascular lesions (28/31, 90.3%), including 15 cases of pseudoaneurysm (15/28, 53.6%), 9 cases of arteriovenous fistula (9/28, 32.1%), and 4 cases of suspicious bleeding spot (4/28, 14.3%). While DSA revealed 31 cases of vascular lesions (100%), including 15 cases of pseudoaneurysm (15/31, 48.4%), 10 cases of arteriovenous fistula (10/31, 32.3%), 6 cases of bleeding spot and (6/31, 19.4%). The serum creatinine level was elevated slightly before mini-PCNL and after DSA embolization (73.1±18.1 vs 92.1±33.6, P <.01). 15 patients (15/31, 48.4%) required blood transfusion, with mean blood transfusion volume of 700 ml ±660 ml (range, 400 ml-1800 ml). The bleeding was controlled without any further severe complications. ConclusionCTA and 3D reconstruction of renal arteries were safe and effective in diagnosing renal arterial bleedings after mini-PCNL, with a sensitivity of 90.3% and a specificity of 100%.

Ex Vivo Evaluation of the Cranial Tibial Artery and Its Compression through Fragment Rotation during Tibia Plateau Levelling Osteotomy: An Angiographic Three-Dimensional Reconstruction.

To illustrate the arterial vascularity of the proximal tibia three-dimensionally and to evaluate the impact of fragment rotation on the cranial tibial artery by tibia plateau levelling osteotomy (TPLO). Radiographic angiography and computed tomography (CT) were performed on 12 pelvic limbs from six large-breed canine cadavers before and after TPLO. Three-dimensional (3D) models of the stifle, including osseous and vascular structures, were obtained, and the integrity of the cranial tibial artery was assessed. Post-TPLO CT images were used to analyze compression of the cranial tibial artery by the rotated fragment. The uncompressed cranial tibial artery caliber, measured proximally and distally to the osteotomy, was 9.52 mm2 (6.07-18.90 mm2). In all adequately rotated fragments, the mean caliber of the artery on the level of the osteotomy was 1.57 mm2 (0.89-2.93 mm2) after TPLO. This represented a significant decrease of approximately 81%. Only slight cross-sectional area decrease (8.8%) was seen in one limb, which was revealed to have insufficient fragment rotation (2.83 mm). Another limb only showed signs of stretching of the artery (31.51%), which was under-rotated and medially displaced. Pre-TPLO 3D reconstructions were mainly consistent with previous anatomic studies except for the distance between tibial cortex and cranial tibial artery, which appeared closer. Sufficient fragment rotation leads to compression of the cranial tibial artery. Intraoperative hemorrhage can be caused by laceration of the main cranial tibial artery or by multiple small branches reaching craniolaterally.

A dissection … of the Dacron?

A dissection … of the Dacron?

Automatic vs manual coronary CT angiography reconstruction for whole-heart coverage CT scanner: a comparison study in general patient population.

Due to the limited temporal resolution and cardiac motion, coronary computed tomography angiography (CCTA) exam is one of the most challenging CT protocols which may require operating radiologist to apply additional phase adjustment or motion correction for image reconstruction. To evaluate image quality between automatic and manual CCTA reconstruction in a 0.25 second rotation time, 16 cm coverage, single-beat, CT scanner with automated phase selection and AI-assisted motion correction. CCTA exams of 535 consecutive patients were included. All exams were first reconstructed with an automatically selected phase. If there was an unacceptable motion artifact, a manual reconstruction process was performed by radiologists. Additionally, automatic image series which consist of auto-phase selection and a follow-up motion correction were reconstructed. For these two manual and automatic image series, a four-point Likert scale rating system was used to evaluate image quality of the coronary artery segment by two experienced radiologists, according to the 18-segment model. Fifty-one patients (9.5%) did not have satisfactory image quality after auto-phase selection. In these patients, the heart rate during scanning was higher (78.3±18.4 bpm) than in the remaining 484 patients (68.9±13.1 bpm). Overall, 734 out of the 918 vessel segments were identified for quality evaluation among 51 patients. Automatic and manual image series were rated as having average Likert scores of 3.48±0.62 and 3.32±0.67 (P < 0.001), respectively. Using a 0.25 second rotation speed, 16 cm z-coverage, CT scanner installed with an AI-assisted motion correction algorithm, the automatic image reconstruction with scanner equipped auto-phase-selection and motion correction algorithm outperforms manually controlled image reconstruction by radiologists. This suggests that the traditional CCTA exam reconstruction workflow could be altered allowing less radiologist involvement and becoming more efficient.

Floating EVAS!

A 79 year old patient, unfit for open surgery, treated for a pararenal aortic aneurysm with the endovascular aneurysm sealing system (EVAS) with three chimneys in both renal arteries and the superior mesenteric artery, was lost to follow up and presented six years later with a type Ia endoleak and sac enlargement to 9 cm. (A) Computed tomography angiography reconstruction of the migrated left EVAS stent (red arrow). (B) The patient was successfully treated with a custom made thoraco-abdominal stent graft with three inner branches, an aorto-uni-iliac endoprosthesis on the right, plug on the left and femorofemoral crossover bypass.Image 1

Mediastinal basal pulmonary artery identification and classification by three-dimensional reconstruction

The primary objective of the present study was to use CT angiography and 3D reconstruction to assess and to classify the mediastinal pulmonary basal segmental arteries. We report a particular type of bifurcated left lower pulmonary artery, namely, the "mediastinal basal pulmonary artery" type, which is the first branch from the proximal the left pulmonary artery (LPA) between the left main bronchus (LMB) and the left superior pulmonary vein (LSPV) and proceeding directly into the lower lobe. There are many types of mediastinal basal pulmonary arteries, and these can be classified worldwide in a unified way and format, which will be beneficial for clinical records, annotation and academic exchange. The mediastinal basal pulmonary arteries are described either as "supernumerary" when duplicating or "displaced" when replacing the normal arterial branching pattern of the lower lobe. The displaced type is more frequent than the supernumerary type. There are 12 types of left mediastinal basilar arteries. This is the first report to categorize the mediastinal basal pulmonary artery, is the first to suggest a system for mediastinal basal pulmonary artery nomenclature, and creates simplified models for use when planning anatomical segmentectomy. Knowledge and recognition of this rare and special condition may facilitate better diagnosis and treatment of these patients.

Vessel-GAN: Angiographic reconstructions from myocardial CT perfusion with explainable generative adversarial networks

Dynamic CT angiography derived from CT perfusion data can obviate a separate coronary CT angiography and the use of ionizing radiation and contrast agent, thereby enhancing patient safety. However, the image quality of dynamic CT angiography is inferior to standard CT angiography images in many studies. This paper proposes an explainable generative adversarial network named vessel-GAN, which resorts to explainable knowledge-based artificial intelligence to perform image translation with increased trustworthiness. Specifically, we design a loss term to better learn the representations of blood vessels in CT angiography images. The loss term based on expert knowledge guides the generator to focus its training on the important features predicted by the discriminator. Additionally, we propose a generator architecture that effectively fuses spatio-temporal representations and further enhances temporal consistency, thereby improving the quality of the generated CT angiography images. The experiment is conducted on a dataset consisting of 232 patients with suspected coronary artery stenosis. Experimental results show that the PSNR value of vessel-GAN is 28.32 dB, SSIM value is 0.91 and MAE value is 47.36. To validate the effectiveness of the proposed synthesis method, we compare that with other image translation frameworks and GAN-based methods. Compared to other image translation methods, the proposed method vessel-GAN can generate more clearly visible blood vessels from source perfusion images. The CTA images generated by vessel-GAN are closer to the real CTA due to the use of adversarial learning. Compared with other GAN-based methods, vessel-GAN can produce sharper and more homogeneous outputs, including realistic vascular structures. The experiment demonstrates that the explainable generative adversarial network has superior performance for it can better control how models learn. Overall, the CT angiography images generated by vessel-GAN can potentially replace a separate standard CT angiography, allowing the possibility of “one-stop” cardiac examination for high-risk coronary artery disease patients who need assessment of myocardial ischemia.

Model-based adaptive filter for a dedicated cardiovascular CT scanner: Assessment of image noise, sharpness and quality

BackgroundFiltered back projection (FBP) and adaptive statistical iterative reconstruction (ASIR) are ubiquitously applied in the reconstruction of coronary CT angiography (CCTA) datasets. However, currently no data is available on the impact of a model-based adaptive filter (MBAF2), recently developed for a dedicated cardiac scanner. PurposeOur aim was to determine the effect of MBAF2 on subjective and objective image quality parameters of coronary arteries on CCTA. MethodsImages of 102 consecutive patients referred for CCTA were evaluated. Four reconstructions of coronary images (FBP, ASIR, MBAF2, ASIR + MBAF2) were co-registered and cross-section were assessed for qualitative (graininess, sharpness, overall image quality) and quantitative [image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR)] image quality parameters. Image noise and signal were measured in the aortic root and the left main coronary artery, respectively. Graininess, sharpness, and overall image quality was assessed on a 4-point Likert scale. ResultsAs compared to FBP, ASIR, and MBAF2, ASIR + MBAF2 resulted in reduced image noise [53.1 ± 12.3, 30.6 ± 8.5, 36.3 ± 4.2, 26.3 ± 4.0 Hounsfield units (HU), respectively; p < 0.001], improved SNR (8.4 ± 2.6, 14.1 ± 3.6, 11.8 ± 2.3, 16.3 ± 3.3 HU, respectively; p < 0.001) and CNR (9.4 ± 2.7, 15.9 ± 4.0, 13.3 ± 2.5, 18.3 ± 3.5 HU, respectively; p < 0.001). No difference in sharpness was observed amongst the reconstructions (p = 0.08). Although ASIR + MBAF2 was non-superior to ASIR regarding overall image quality (p = 0.99), it performed better than FBP (p < 0.001) and MBAF2 (p < 0.001) alone. ConclusionThe combination of ASIR and MBAF2 resulted in reduced image noise and improved SNR and CNR. The implementation of MBAF2 in clinical practice may result in improved noise reduction performance and could potentiate radiation dose reduction.

Generative adversarial networks improve interior computed tomography angiography reconstruction

In interior computed tomography (CT), the x-ray beam is collimated to a limited field-of-view (FOV) (e.g. the volume of the heart) to decrease exposure to adjacent organs, but the resulting image has a severe truncation artifact when reconstructed with traditional filtered back-projection (FBP) type algorithms. In some examinations, such as cardiac or dentomaxillofacial imaging, interior CT could be used to achieve further dose reductions. In this work, we describe a deep learning (DL) method to obtain artifact-free images from interior CT angiography. Our method employs the Pix2Pix generative adversarial network (GAN) in a two-stage process: (1) An extended sinogram is computed from a truncated sinogram with one GAN model, and (2) the FBP reconstruction obtained from that extended sinogram is used as an input to another GAN model that improves the quality of the interior reconstruction. Our double GAN (DGAN) model was trained with 10 000 truncated sinograms simulated from real computed tomography angiography slice images. Truncated sinograms (input) were used with original slice images (target) in training to yield an improved reconstruction (output). DGAN performance was compared with the adaptive de-truncation method, total variation regularization, and two reference DL methods: FBPConvNet, and U-Net-based sinogram extension (ES-UNet). Our DGAN method and ES-UNet yielded the best root-mean-squared error (RMSE) (0.03 ± 0.01), and structural similarity index (SSIM) (0.92 ± 0.02) values, and reference DL methods also yielded good results. Furthermore, we performed an extended FOV analysis by increasing the reconstruction area by 10% and 20%. In both cases, the DGAN approach yielded best results at RMSE (0.03 ± 0.01 and 0.04 ± 0.01 for the 10% and 20% cases, respectively), peak signal-to-noise ratio (PSNR) (30.5 ± 2.6 dB and 28.6 ± 2.6 dB), and SSIM (0.90 ± 0.02 and 0.87 ± 0.02). In conclusion, our method was able to not only reconstruct the interior region with improved image quality, but also extend the reconstructed FOV by 20%.

Self-supervised learning-based diffeomorphic non-rigid motion estimation for fast motion-compensated coronary MR angiography

PurposeTo accelerate non-rigid motion corrected coronary MR angiography (CMRA) reconstruction by developing a deep learning based non-rigid motion estimation network and combining this with an efficient implementation of the undersampled motion corrected reconstruction. MethodsUndersampled and respiratory motion corrected CMRA with overall short scans of 5 to 10 min have been recently proposed. However, image reconstruction with this approach remains lengthy, since it relies on several non-rigid image registrations to estimate the respiratory motion and on a subsequent iterative optimization to correct for motion during the undersampled reconstruction. Here we introduce a self-supervised diffeomorphic non-rigid respiratory motion estimation network, DiRespME-net, to speed up respiratory motion estimation. We couple this with an efficient GPU-based implementation of the subsequent motion-corrected iterative reconstruction. DiRespME-net is based on a U-Net architecture, and is trained in a self-supervised fashion, with a loss enforcing image similarity and spatial smoothness of the motion fields. Motion predicted by DiRespME-net was used for GPU-based motion-corrected CMRA in 12 test subjects and final images were compared to those produced by state-of-the-art reconstruction. Vessel sharpness and visible length of the right coronary artery (RCA) and the left anterior descending (LAD) coronary artery were used as metrics of image quality for comparison. ResultsNo statistically significant difference in image quality was found between images reconstructed with the proposed approach (MC:DiRespME-net) and a motion-corrected reconstruction using cubic B-splines (MC:Nifty-reg). Visible vessel length was not significantly different between methods (RCA: MC:Nifty-reg 5.7 ± 1.7 cm vs MC:DiRespME-net 5.8 ± 1.7 cm, P = 0.32; LAD: MC:Nifty-reg 7.0 ± 2.6 cm vs MC:DiRespME-net 6.9 ± 2.7 cm, P = 0.81). Similarly, no statistically significant difference between methods was observed in terms of vessel sharpness (RCA: MC:Nifty-reg 60.3 ± 7.2% vs MC:DiRespME-net 61.0 ± 6.8%, P = 0.19; LAD: MC:Nifty-reg 57.4 ± 7.9% vs MC:DiRespME-net 58.1 ± 7.5%, P = 0.27). The proposed approach achieved a 50-fold reduction in computation time, resulting in a total reconstruction time of approximately 20 s. ConclusionsThe proposed self-supervised learning-based motion corrected reconstruction enables fast motion-corrected CMRA image reconstruction, holding promise for integration in clinical routine.

頭蓋底骨折後遅発性に鼻出血を契機に発見された内頸動脈仮性瘤の1例(A case of delayed discovery of a internal carotid artery pseudoaneurysm by nosebleeds after skull base fracture)

要旨 頭部外傷に伴う頭蓋底骨折はときに仮性動脈瘤を合併する。今回我々は，頭蓋底骨折後受傷時に損傷を認めなかった右内頸動脈に遅発性に仮性動脈瘤を形成した1例を経験したので報告する。症例は74歳の男性。約3mの高さから墜落し顔面を強打した。救急隊接触時，外表上頭部・顔面に外傷を認め，発語不能であったため，重症頭部外傷が疑われ当院へ搬送された。来院時CT検査において右視神経損傷を伴う頭蓋底骨折，脳挫傷，外傷性くも膜下出血，右肩甲骨骨折，多発肋骨骨折を認めたが，仮性動脈瘤は認めなかった。上記各外傷に対し保存的加療を行い，第19病日軽快転医となった。第38病日初回の鼻出血を認めた。第47病日中等量の鼻出血を認め，鼻腔内ガーゼ充填で止血を得た。第79病日より隔日で鼻出血を認めるようになったが，耳鼻科診察では鼻粘膜に特記すべき異常を認めなかった。第84病日多量の鼻出血と血圧低下，冷汗を認め，造影CTで右内頸動脈に仮性動脈瘤を認めたため，当院へ再度転医となった。第85病日右浅側頭動脈–中大脳動脈吻合術および右内頸動脈瘤コイル塞栓術を行い，第90病日MRAで瘤への血流がないことを確認した。第96病日に転医し，第106病日独歩退院となった。本症例では頭部外傷後の鼻出血により，仮性動脈瘤を発見し得た。頭蓋底骨折後の血管評価は受傷時に損傷を認めなくても継時的な画像評価などを慎重に行う必要がある。

Alternative Endograft Aortoiliac Reconstruction for Iliac Branch Endoprostheses

Endovascular treatment of complex common iliac artery (CIA) and internal iliac artery (IIA) aneurysms using iliac branch endoprostheses (IBE) has proven safe and effective. Instructions for use (IFU) require deployment of current IBE technology with the corresponding manufacturer's modular bifurcated aortic endograft. Concomitant aortoiliac occlusive disease, inadequate renal artery-iliac bifurcation length, and unfavorable aortic anatomy preclude on-label IBE deployment. This study aimed to evaluate the technical feasibility and safety of Alternative Endograft Aortoiliac Reconstruction (AEGAR) for branched endovascular treatment of complex iliac artery aneurysms. In 7 consecutive patients with CIA or IIA aneurysms, computed tomography angiography (CTA) and center-line reconstruction revealed aortoiliac anatomy incompatible with the current IBE IFU due to inadequate proximal CIA landing zone (n=7), inadequate renal artery to iliac bifurcation length (n=2), compromised aortic anatomy (n=3), or short infrarenal neck <15 mm (n=1), either alone or in combination. To overcome these restrictions and facilitate IBE deployment, aortoiliac reconstruction was performed using the Endologix AFX, Endologix Ovation limbs or the Medtronic Endurant II platforms (AEGAR technique). All internal iliac artery reconstructions and external iliac artery extensions were performed using the Gore VBX or Viabahn stent grafts. Technical success was defined as successful delivery of all endograft components without migration or endoleak. The mean patient age was 69 years (range 52-82 years; 6 male). Four patients had bilateral CIA aneurysms and 3 patients had unilateral CIA aneurysms (mean diameter 4.3cm; range 2.2-7 cm). There were 13 IIA VBX stent grafts used for a total of 9 IIAs treated with IBE (bilateral IBE=2 patients). The mean fluoroscopy time was 38.8 min (range 21.3-64.3 min) and the mean contrast volume was 168.5 mL (range 122-226 mL). Technical success was achieved in all patients and there were no perioperative complications. Mean hospital-stay was 2.2 days (range 1-3 days). Follow-up ranged from 82-957 days (mean=487 days). At last follow-up, all patients were alive without cardiovascular morbidity; and CTA revealed stable or decreased aneurysm size, patent endografts, and no evidence of endoleak or migration. The AEGAR technique can be used to safely and effectively overcome certain aortoiliac anatomic constraints that preclude use of current IBE technology. We encourage broader use of these alternative endografts in pertinent anatomic configurations.

Calcification prevalence in different vascular zones and its association with demographics, risk factors, and morphometry.

Vascular calcification is associated with a higher incidence of cardiovascular events, but its prevalence in different vascular zones and the influence of demographics, risk factors, and morphometry remain insufficiently understood. Computerized tomography angiography scans from 211 subjects 5-93 yr old (mean age 47 ± 24 yr, 127 M/84 F) were used to build 3D vascular reconstructions and measure arterial diameters, tortuosity, and calcification volumes in six vascular zones spanning from the ascending thoracic aorta to the pelvic arteries. A machine learning random forest algorithm was used to determine the associations between calcification in each zone with demographics, risk factors, and vascular morphometry. Calcification appeared during the fourth decade of life and was present in all subjects after 65 yr. The abdominal aorta and the iliofemoral segment were the first to develop calcification, whereas the ascending thoracic aorta was the last. Demographics and risk factors explained 33-59% of the variation in calcification. Age, creatinine level, body mass index, coronary artery disease, and hypertension were the strongest contributors, whereas the effects of sex, race, tobacco use, diabetes, dyslipidemia, and alcohol and substance use disorders on calcification were small. Vascular morphometry did not directly and independently affect calcium burden. Vascular zones develop calcification asynchronously, with distal segments calcifying first. Understanding the influence of demographics and risk factors on calcium prevalence can help better understand the disease pathophysiology and may help with the early identification of patients that are at higher risk of cardiovascular events.NEW & NOTEWORTHY We investigated the prevalence of vascular calcification in different zones of the aorta and pelvic arteries using computerized tomography angiography reconstructions and have applied machine learning to determine how calcification is affected by demographics, risk factors, and morphometry. The presented data can help identify patients at higher risk of developing vascular calcification that may lead to cardiovascular events.

Time‐encoded golden angle radial arterial spin labeling: Simultaneous acquisition of angiography and perfusion data

The objective of the current study was to combine a time‐encoded pseudocontinuous arterial spin labeling (te‐pCASL) scheme with a golden angle radial readout for simultaneous acquisition of angiography and perfusion images from one single dataset, both in a highly flexible single‐slice approach as well as within a multislice setting. A te‐pCASL preparation and the golden angle radial readout were both used as a temporal resolution tool to retrospectively choose the temporal window for the reconstruction of both angiography and perfusion images from a single‐slice dataset. The temporal window could be chosen retrospectively and adjusted to the hemodynamics of the volunteer on the scanner for the single‐slice dataset. Angiographic images were reconstructed at a minimum temporal resolution of 69 ms. For the perfusion phase, only the densely sampled center of k‐space was included in the reconstruction. For a multislice acquisition, the golden angle radial readout allowed reconstruction of images with different spatial resolutions to provide angiographic and perfusion information over 10 slices. The te‐pCASL preparation was used as the only source for dynamic information. The multislice acquisition shows the ability of the golden angle radial readout to display the inflow of the labeled blood into the arteries as well as the perfusion in the tissue with full brain coverage. By combining a te‐pCASL preparation with a golden angle radial readout, single‐slice high temporal resolution angiography and good quality perfusion images were reconstructed in a flexible manner from a single dataset. Optimizing the golden angle radial readout for reconstructions at multiple spatial resolutions allows for multislice acquisition.

Reducing contrast medium dose with low photon energy images in renal dual-energy spectral CT angiography and adaptive statistical iterative reconstruction (ASIR)

To evaluate the value of using low energy (keV) images in renal dual-energy spectral CT angiography (CTA) and adaptive statistical iterative reconstruction (ASIR) to reduce contrast medium dose. 40 patients with renal CTA on a Discovery CT750HD were randomly divided into two groups: 20 cases (Group A) with 600 mgI kg-1 and 20 cases (Group B) with 300 mgI kg-1. The scan protocol for both groups was: dual-energy mode with mA selection for noise index of 10 HU, pitch 1.375:1, rotating speed 0.6 s/r. Images were reconstructed at 0.625 mm thickness with 40%ASIR, Group A used the conventional 70keV monochromatic images, and Group B used monochromatic images from 40 to 70 keV at 5 keV interval for analysis. The CT values and standard deviation (SD) values of the renal artery and erector spine in the plain and arterial phases were measured with the erector spine SD value representing image noise. The enhancement degree of the renal artery (ΔCT = CT(arterial) -CT(plain)), signal-to-noise ratio (SNR=CTrenal-artery/SDrenal-artery) and contrast-to-noise ratio (CNR=(CTrenal-artery-CTerector spine)/SDerector-spine) were calculated. The single factor analysis of variance was used to analyze the difference of ΔCT, SNR and CNR among image groups with p < 0.05 being statistically significant. The subjective image scores of the groups were assessed blindly by two experienced physicians using a 5-point system and the score consistency was compared by the κ test. Contrast medium dose in the 300 mgI kg-1 group was reduced by 50% compared with the 600 mgI kg-1 group, while radiation dose was similar between the two groups. The subjective scores were 4.00 ± 0.65, 4.50 ± 0.60 and 3.70 ± 0.80 for images at 70 keV (600 mgI kg-1 group), 40 keV (300 mgI kg-1 group) and 45 keV (300 mgI kg-1 group), respectively with good consistency between the two reviewers (p > 0.05). The 40 keV images in the 300 mgI kg-1 group had similar ΔCT (469.77 ± 86.95 HU vs 398.54 ± 73.68 HU) and CNR (15.52 ± 3.32 vs 18.78 ± 6.71) values as the 70 keV images in the 600 mgI kg-1) group but higher SNR values (30.19 ± 4.41 vs 16.91 ± 11.12, p < 0,05). Contrast dose may be reduced by 50% while maintaining image quality by using lower energy images combined with ASIR in renal dual-energy CTA. Combined with ASIR and energy spectrum, can reduce the amount of contrast dose in renal CTA.

Morphologic variants of the Cerebral Arterial Circle on computed tomographic angiography (CTA): a large retrospective study.

To confirm and illustrate the great variability of morphology of the Cerebral Arterial Circle (CAC)-also commonly called "Circle of Willis"-in current clinical Computed Tomography Angiography (CTA) practice. Computed Tomographic Angiographic 3D Volume Rendering reconstructions of the CAC performed in a series of 511 patients were retrospectively reviewed and classified following their anatomic configuration. An amount of 27 CAC configurations were listed. Complete and "nearly complete" (1 missing segment) CACs were found in 115 (22.58%) and 157 (28.6%) patients. The posterior arch was much more frequently incomplete (374 patients = 73.18%) than the anterior arch (96 patients = 18.4%). The main cause was a high prevalence of missing posterior communicating arteries (PCoAs). The left or right PCoA were unilaterally lacking in 156 patients (30.53%) and both PCoAs were lacking in 179 patients (35.02%). Cases with 2 and 3 missing segments were observed in 184 (36%) and 44 patients (8.6%). Precarious situations were also identified including 7 cases (1.4%) of complete isolation of the middle cerebral artery (MCA), 11 cases (2.15%) of absence of interhemispheric supply, 205 cases (40.1%) of full separation of the carotid and vertebra-basilar (VB) territories and 44 cases (8.6%) of full separation of the three main arterial axes (both ICAs and VB). The prevalence of Fetal Posterior Cerebral Arteries (FPCA) variants was also reported. A "Full" FPCA was found unilaterally in 48 (9.4%) and bilaterally in 13 (2.54%) of patients. Apart from agenesis and hypoplasia reported in our study, various other variations of the anterior complex of the CAC (ACoA and A2 segments of the ACA) were also noted. CTA with 3D Volume Rendering may powerfully assess the numerous variations of the CAC. This assessment is of prime importance for the evaluation of patients presenting with risk factors or in whom neurosurgery, cardiac surgery, interventional radiology or carotid endarterectomy (CEA) are being considered.

Endovascular treatment of common iliac artery aneurisms

To demonstrate endovascular management of common iliac artery aneurysms with iliac branch devices and to discuss some technical aspects of these interventions including bilateral procedures. Endovascular abdominal aortic aneurysm repair with concomitant implantation of iliac branch devices was performed in 9 patients at the Petrovsky National Research Center of Surgery for the period from January 2019 to December 2020. Mean age of patients was 64.8± years (min 52; max 72 years). Preoperative planning and morphometric analysis were based on CT data with a slice thickness of 1 mm. Angiographic reconstruction was made using Osirix 3D software (OsiriX Foundation, Geneva, Switzerland). Abdominal aortic aneurysm was combined with common iliac artery aneurysm in 7 patients (77.7%). Three (33.3%) patients had isolated common iliac artery aneurysm without significant abdominal aorta enlargement (Reber type I). Bilateral common iliac artery aneurysms were detected in 1 (11.1%) patient. All patients had iliac artery aneurysms over 4 cm. Iliac branch device implantation was accompanied by endovascular abdominal aneurysm repair in all patients. Technical success rate was 100%. Six-month results were followed-up in 5 patients (55.5%), annual outcomes - in 2 patients (22.2%). Control examination consisted of a telephone interview, ultrasound of abdominal aorta, pelvic and lower limb arteries and computed tomography. All patients had no endoleaks, stent-graft thrombosis, as well as signs of ischemia of pelvic organs and lower extremities. Incidence of iliac artery aneurysm combined with abdominal aortic aneurysms is about 20%. Until recently, treatment of these patients was performed exclusively with covering of internal iliac artery. Improvement of technologies and development of iliac branch devices made it possible to preserve blood flow in internal iliac artery after endovascular management. This approach allowed avoiding of ischemic complications associated with embolization of internal iliac arteries.

Management of Acute Uncomplicated Stanford B Aortic Dissection in The Era of Endovascular Repair: A Case Report

Introduction: Uncomplicated type B aortic dissections have been traditionally treated with medication therapy. While it may provide good short-term results, longterm prognosis may be less favorable. With improvements in endovascular repair and the potential risk of disease progression, thoracic endovascular aortic repair (TEVAR) has been considered inpatients with uncomplicated type B aortic dissection. We present the case of 78-year-old gentleman who presented with acute uncomplicated type B aortic dissection managed by endovascular repair Case illustration: A 78 year-old hypertensive patient admitted to the hospital with persistent chest discomfort and cough for 2 weeks. The CT aortic angiogram showed type B dissection. Based on the recent guidelines, TEVAR should be considered in patients with uncomplicated type B aortic dissection, thus we prepared the patient for TEVAR procedure. First we established multidisciplinary vascular team for the pre-procedural preparation of the patient. We perform careful measurement through detailed CT angiography reconstruction from carotid to femoral arteries. We found proximal diameter was 30-35mm, distal diameter was 23mm and landing zone right after left brachial ostium, suitable for stent graft Valiant Captivia 36-32x150mm. The CT also showed that both femoral artery were normal, we decided to use right femoral artery as the access. We proceed to the procedure 2 days later, under general anaesthesia, digital subtraction angiography revealed dissection of descending aorta, and selected device was inserted. Subsequent contrast injection revealed total occlusion of the false lumen. Patient was transferred to ICU for postprocedural care, and extubated the day after. The hospital stay was uneventful, and one-month follow up CT shows no endoleak. Conclusion : Management of uncomplicated Stanford B dissections is very challenging. TEVAR has emerged as an alternative to surgery with lower morbidity and mortality rates that might offer good long-term results.