3D CTA Research Articles

Abstract 2571: Quantitative Analysis of Cobalt Alloy Clip Artifacts in 64 channel Three Dimensional CT Angiography and Introducing Strategies for Minimizing Metallic Artifacts

Objective Clip artifacts on postoperative CT scans after aneurysmal clipping, can create confusion, especially in cases of cobalt alloy clips. Mathematic analysis of the parameters influencing the degree of clip artifact in 64-channel 3 dimensional CT angiography (3D CTA) was conducted to develop methods for minimizing metallic artifacts. Materials and Methods CT images from 60 cases with single straight Sugita cobalt alloy clips (Mizuho Ikakogyo Co., Tokyo) were analyzed. The degree of the angle between the imaging acquisition gantry angle and clip blade on the CT axial scan (x, y) and on the lateral scout view (z) was measured as independent variables. The length of the clip blade was also measured. Analysis of whether the spring of the clip was included in the 5mm thick scan slide was performed. The dependent variables were the maximal diameter of the white artifact, degree of the symmetrical angle of the streak artifact and the maximal diameter of clip artifact in 3D volume rendering. Univariate and multivariate analysis was conducted to elucidate relationship between each parameters and each type of clip artifacts. Results The degree of the angle between z axis and clip blade was negatively correlated with the amount of white artifact (p<0.0001, R=-0.589) and positively with the streak artifact (angle of the streak artifact: p<0.0001, R=0.636; number of the streak artifact: p<0.0001, R=0.505). When the spring of the clip was included parallel in scan section, the amount of white artifact was increased (p<0.0001). On multiple linear regression analysis, angle of clip blade to z axis was the major parameter influencing all kinds of artifacts (white artifact: p<0.005, angle of the streak artifact: p<0.0001, number of the streak artifact: p<0.0001). Conclusions Metallic artifact was increased when the degree of angle between the clip blade and z axis became near to zero. Clip artifacts after aneurysmal clipping could be minimized with simple maneuvers such as minimal changes of the scan gantry angle on the lateral scout view if the clip blade was parallel to the gantry angle or the clip spring portion was included in the scan cross section.

Abstract 3303: Detection of cerebral vasospasm using Dynamic CT: Analysis of Volume Perfusion CT Maps and 4D-CT Angiography

Introduction: Cerebral vasospasm with a raised risk for secondary ischemia is a frequent complication after subarachnoid hemorrhage (SAH). The early diagnosis of focal or global cerebral hypoperfusion is important in order to allow treatment before irreversible ischemic damage occurs (intensive care and/or neurointervention). We tested, whether the implementation of “whole brain” volume Perfusion CT (VPCT) for the examination of patients with suspected cerebral vasospasm delivers relevant information about the localization and characteristics of arterial vasospasm and the volume at risk of secondary infarction. Patients and Methods: Patients were eligible for this study, if they had been admitted to our department with suspicion of cerebral vasospasm due to SAH. Patients first received a non-contrast CT of the brain to exclude acute hydrocephalus. After that, VPCT was performed. CT angiographic axial and coronal maximum-intensity projections (MIP) were generated from thin slice recons of the VPCT dataset at peak arterial time. Images were assessed for presence of arterial vasospasm or occlusion and compared with conventional CTA or DSA. The distribution of ischemic lesions was analyzed on 3D perfusion parameter maps of cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT) and time to drain (TTD). Results: 11 patients with SAH were examined with VPCT. In all patients, focal areas of cerebral hypoperfusion were detected on the color coded VPCT parameter maps. The highest sensitivity was found for MTT and TTD. Focal reductions of CBV strongly correlated with infarction on follow-up CT. 8 patients (73%) had focal stenotic lesions of intracranial artery segments due to vasospasm visible on the thin MIP reconstructions of the 4D CTA arterial phase. All of these stenotic lesions were also visible on conventional CTA or DSA, resulting in 100% sensitivity of the 4D CTA reconstructions. In 2 patients, balloon angioplasty of the vasospastic segments was performed subsequently; in both patients, VPCT showed normalization of both the perfusion maps and the vessel diameter afterwards. Conclusion: VPCT is a non-invasive method that allows detecting cerebral vasospasm in patients suffering from SAH. It has the potential to demonstrate brain areas with a focal perfusion deficit as well as vasospastic arterial segments. DSA will remain the gold standard for detection of cerebral vasospasm, but VPCT has the potential to improve diagnosis and treatment decisions in patients suffering from vasospasm due to SAH.

Clinical and multidetector CT follow-up results of renal artery aneurysms treated by detachable coil embolization using 3D rotational angiography

There are very few reports regarding the use of 3D rotational angiography (3D RA) in embolization of renal artery aneurysms (RAAs). No valuable data have been reported on the follow-up result of coil embolization for RAAs on computed tomography (CT). Purpose To evaluate the clinical and multidetector computed tomography (MDCT) follow-up results of renal artery aneurysms treated by detachable coil embolization using 3D RA. Six patients diagnosed with RAAs were included. Five patients underwent detachable coil embolization. Five patients underwent 3D RA and the parameters used for planning endovascular treatment obtained by 2D CT, reformatted 3D CT angiography (3D CTA), 2D digital subtraction angiography (2D DSA) and 3D RA were compared. The postembolization MDCT follow-up findings were analyzed retrospectively. The technical success rate for detachable coil embolization was 40%. The 3D CTA showed the dome-to-neck ratio (DNR) and tangential view of the renal artery aneurysm in five patients (83.3%) and the 2D CT showed it in four (66.7%). An optimal working angle assessment could not be obtained on the 2D CT and 3D CTA. The 3D RA showed the DNR, tangential view, and optimal working angle in all patients. Renal infarction occurred in three patients and postprocedural hypertension developed in two patients during the follow-up period. The 3D RA was useful in preoperative determination of adequate working angle for detachable coil embolization of RAAs. Late complications of detachable coil embolization for RAAs were renal infarction and hypertension.

Three-dimensional computed tomographic angiography to predict weight and volume of deep inferior epigastric artery perforator flap for breast reconstruction

Three-dimensional computed tomographic angiography (3D CTA) can be used preoperatively to evaluate the course and caliber of perforating blood vessels for abdominal free-flap breast reconstruction. For postmastectomy breast reconstruction, many women inquire whether the abdominal tissue volume will match that of the breast to be removed. Therefore, our goal was to estimate preoperative volume and weight of the proposed flap and compare them with the actual volume and weight to determine if diagnostic imaging can accurately identify the amount of tissue that could potentially to be harvested. Preoperative 3D CTA was performed in 15 patients, who underwent breast reconstruction using the deep inferior epigastric artery perforator flap. Before each angiogram, stereotactic fiducials were placed on the planned flap outline. The radiologist reviewed each preoperative angiogram to estimate the volume, and thus, weight of the flap. These estimated weights were compared with the actual intraoperative weights. The average estimated weight was 99.7% of the actual weight. The interquartile range (25th to 75th percentile), which represents the "middle half" of the patients, was 91-109%, indicating that half of the patients had an estimated weight within 9% of the actual weight; however, there was a large range (70-133%). 3D CTA with stereotactic fiducials allows surgeons to adequately estimate abdominal flap volume before surgery, potentially giving guidance in the amount of tissue that can be harvested from a patient's lower abdomen.

Ruptured aneurysm with extravasation observed in four-dimensional computed tomography angiography

We report a case of subarachnoid hemorrhage with a ruptured aneurysm in the anterior communicating artery. On multiphase dynamic contrast-enhanced four-dimensional computed tomography angiography (4D CTA), we observed active bleeding from the aneurysm that manifested over time with a corkscrew-like, spindle-like, and lobulated appearance and nebulous enhancement, characteristics reported only individually previously. The volume data for 4D CTA is easy to obtain with newly developed multidetector-row computed tomography, and 4D CTA can be used for evaluating anatomical aspects, hemodynamics, and treatment selection in cases of a ruptured cerebral aneurysm.

Developmental Venous Anomalies (DVA): What Are They Really?

The aim of this paper is to analyse the pathophysiology of 3 DVA cases from our institution, review the literature and propose a classification of these lesions. The pathophysiology of DVAs were analysed with CT perfusion (CTP), 4 dimensional dynamic computed tomography angiography (4D CTA) and catheter digital subtraction angiography. Symptomatic DVAs may be caused by associated lesions and compression of neural structures by the DVAs. The imbalance between the inflow and outflow of these lesions, including venous ischaemia, has also been postulated as a cause. Our analysis showed that increased cerebral blood flow (CBF) and cerebral blood volume (CBV) and decreased mean transit time (MTT) and time to peak (TTP) were found in DVAs with micro arteriovenous shunting. DVAs without shunting had raised MTT and TTP instead. We postulate that the arteriovenous shunting resulted in arterial steal and chronic hypoxia which could be a pathophysiological mechanism for symptomatic DVAs. CTP and 4D CTA are effective non invasive tools to study DVAs. A classification is proposed.

Blood Velocity Calculated From Volumetric Dynamic Computed Tomography Angiography

Though functional intravascular parameters such as blood velocity and direction of blood flow are available via imaging modalities such as Doppler ultrasound and phase contrast magnetic resonance imaging, such quantitative information is not yet supported by computed tomography (CT). In this study, we examined a method to calculate intra-arterial blood velocity from contrast-enhanced dynamic CT angiography (4D CTA) using the unique advantages of a volumetric 320 detector row scanner. Contrast boluses were injected into a flow phantom under volumetric 4D CTA examination. Two pipe diameters were tested, each diameter with 4 various flow velocities, creating 8 independent flow conditions. The internal carotid arteries of 5 patients (10 arteries in total) were subjected to a similar dynamic CTA examination and reconstructed with a 1-second temporal resolution through the arterial phase. Intraluminal velocities were calculated using distance between 2 regions of interest placed proximally and distally over the vessel, divided by delay in time to peak of contrast arrival in each region of interest. Results were compared with flow velocities attained by quantitative magnetic resonance angiography in vivo. Phantom experiments demonstrate reasonable agreement between calculated and measured intraluminal velocity (P = 0.05). Similarly, in vivo blood velocity calculations in all internal carotid arteries show agreement with results attained by quantitative magnetic resonance angiography. Intraluminal blood velocity may be estimated from first-pass contrast bolus profiles acquired via volumetric 4D CTA examinations.

Neuroimaging by 320-row CT: is there a diagnostic benefit or is it just another scanner? A retrospective evaluation of 60 consecutive acute neurological patients

320-row CT enables dynamic CT angiography (4D CTA) of the entire intracranial circulation and whole-brain perfusion imaging (CTP). Sixty acute patients with neurological symptoms underwent various 320-row CT-specific protocols, including combined 4D CTA and CTP. Clinical and neuroradiological records were assessed for presumptive diagnoses, final diagnoses, supplementary and follow-up imaging studies. Additional diagnostic benefits delivered by 320-row CT were noted. Out of 60 procedures, 59 were accomplished successfully. Ischemia (n = 19), intracerebral hemorrhage (n = 7) and transient ischemic attacks (n = 10) were the major final diagnoses. Except one small cortical and two small subcortical infarctions all ischemias were diagnosed. All hemorrhages were diagnosed together with their underlying vascular pathology in five atypical cases. In conclusion, 320-row CT is a technically robust procedure being suitable for comprehensive neuroimaging of acute patients. It can provide dynamic angiographic and perfusion data of the whole brain and can deliver additional diagnostic information not available by standard CT.

Detection of intracranial aneurysms using three-dimensional multidetector-row CT angiography: Is bone subtraction necessary?

Purpose The aim of this study was to evaluate the usefulness of three-dimensional CT angiography (3D CTA) with bone subtraction in a comparison with 3D CTA without bone subtraction for the detection of intracranial aneurysms. Materials and methods Among 337 consecutive patients who had intracranial aneurysms detected on 3D CTA, 170 patients who underwent digital subtraction angiography (DSA) were included in the study. CTA was performed with a 16-slice multidetector-row CT (MDCT) scanner. We created the 3D reconstruction images with and without bone subtraction by using the volume rendering technique. Three neuroradiologists in a blinded fashion interpreted both 3D CTA images with and without bone subtraction. The diagnostic accuracy of both techniques was evaluated using the alternative free-response receiver operating characteristic (ROC) analysis. The sensitivity and positive predictive value were also evaluated. Results A total of 200 aneurysms (size: 2–23 mm) were detected in 170 patients. The area under the receiver operating characteristic curve (Az) for 3D CTA with bone subtraction (mean, Az = 0.933) was significantly higher than that for 3D CTA without bone subtraction (mean, Az = 0.879) for all observers ( P < 0.05). The sensitivity of 3D CTA with bone subtraction for three observers was 90.0, 92.0 and 92.5%, respectively, while the sensitivity of 3D CTA without bone subtraction was 83.5, 83.5 and 87.5%, respectively. No significant difference in positive predictive value was observed between the two modalities. Conclusions 3D CTA with bone subtraction showed significantly higher diagnostic accuracy for the detection of intracranial aneurysms as compared to 3D CTA without bone subtraction.

Adaptations of MARACAS algorithm to the segmentation of the carotid bifurcation and stenosis quantification in CTA images

This paper describes a 3D CTA image segmentation method submitted to the CLS09 contest (Carotid Lumen Segmentation and Stenosis Quantification) held in conjunction with the MICCAI 2009 conference. First, images are denoised to improve image quality and posterior segmentation. Second, region-based measurements are performed to differentiate possible vessels from other structures. Then, edge-driven metrics are used to allow vessel separation from nearby structures. Using, both edge-driven and region-based metrics a filter is used to enhance the vessels. The vessels of interest are extracted by use of the provided initialization points and of a model-driven segmentation algorithm. Using the obtained result, the final stage is devoted to stenosis quantification.

Vesselness-based 2D–3D registration of the coronary arteries

Robust and accurate automated co-registration of the coronary arteries in 3D CTA and 2D X-ray angiography during percutaneous coronary interventions (PCI), in order to present a fused visualization. A novel vesselness-based similarity measure was developed, that avoids an explicit segmentation of the X-ray image. A stochastic optimizer searches the optimal registration using the similarity measure. Both simulated data and clinical data were used to investigate the accuracy and capture range of the proposed method. The experiments show that the proposed method outperforms the iterative closest point method in terms of accuracy (average residual error of 0.42 mm vs. 1.44 mm) and capture range (average 71.1 mm/20.3 degrees vs. 14.1 mm/5.2 degrees ). The proposed method has proven to be accurate and the capture range is ample for usage in PCI. Especially the absence of an explicit segmentation of the interventionally acquired X-ray images considerably aids the robustness of the method.

320-slice CT neuroimaging: initial clinical experience and image quality evaluation

The aim of this study was to report initial clinical experience with a 320-slice CT scanner and to perform an image quality evaluation. 26 patients with presumptive cerebrovascular pathology underwent 320-slice CT. Single-rotation CT of the head, incremental CT angiography (three-dimensional (3D) CTA) as well as four-dimensional whole-brain CTA (4D CTA) and whole-brain CT perfusion (CTP) were performed and the resulting images were assessed for quality and compared with those obtained with 64-slice CT protocols. 320-slice CT neuroimaging could be performed in all cases. The image quality of 320-slice CT of the head and 3D CTA was inferior to that of the 64-slice protocols. The image quality of 4D 320-slice CTA was rated as inferior to both 320- and 64-slice 3D CTA. 4D CTA-CTP imaging added information with pivotal clinical implications. 320-slice CT neuroimaging is feasible technique that permits whole-brain 4D imaging and has the potential to identify pathologies with altered haemodynamics. However, image quality is a limitation of this technique at present.

Follow-up study on in-stent thrombosis after carotid stenting using multidetector CT angiography

The purpose of the present study was to evaluate the role of multidetector three-dimensional computed tomography angiography (3D CTA) for evaluating both the residual arterial lumen and the sequential change in the intraluminal diameter and thrombus formation following carotid artery stenting (CAS). Twenty consecutive patients consisting of 23 successfully stented carotid arteries were examined by 3D CTA with volume-rendering at 2, 4, 8, 12 weeks and 6, 12 months of follow-up. The eccentric in-stent hypodense area could be detected in ten of 23 (43.5%) carotid arteries at 2 weeks of follow-up, and they then gradually declined until they almost disappeared at 12 weeks. Eccentric in-stent hypodense areas in the acute and subacute phase (up to 12 weeks after CAS) were found in nine out of 16 carotid arteries with longer stents (3 or 4 cm in size) deployed across the carotid bifurcation, whereas no eccentric in-stent hypodense area could be observed in the patients with a short stent (2 cm) deployed only to the internal carotid artery. Seven of the ten observed eccentric hypodense areas presented on the dorsal surface at the carotid bifurcation level. Carotid 3D CTA for evaluating residual lumen and in-stent thrombus formation after CAS is considered to be a useful diagnostic method. To avoid stent occlusion, both the acute and subacute phases following CAS (up to 12 weeks) call for the administration of appropriate anti-platelet therapy and careful observations of the patients.

Preoperative evaluation of the 64-slice spiral CT three dimensional angiography for vascular invasion in gastric cancer

To evaluate the preoperative diagnosis value of 64-slice spiral CT three dimensional angiography (3D CTA) for the vascular invasion in gastric cancer. CT images of 40 patients diagnosed as gastric cancer by endoscope,who proceeded to surgical exploration from August 2006 to December 2007,were collected. These images were rebuilt by 3D CTA to judge vascular invasion by gastric cancer in comparison with the surgical finding as standard reference. Successful 3D CTA reconstructions were performed for all these 40 patient images. Out of 40 cases, 14 cases presented vascular invasion in the 3D CTA, and 12 of 14 cases were proved to have vascular invasion in the surgery. For assessing vascular invasion with CTA, the sensitivity was 98.1% and the specificity was 96.4% respectively (Chi Square chi(2)=0.0099,P>0.05). There was no significant differences regarding vascular invasion in gastric cancer between preoperative 3D CTA assessment and surgical finding. Sixty-four-slice spiral CT 3D angiography is effective in assessing vascular invasion in gastric cancer and is also valuable in clinical application.

A Classification of Unruptured Middle Cerebral Artery Bifurcation Aneurysms that can Help in Choice of Clipping Technique

Middle cerebral artery (MCA) aneurysms comprise 20-25% of all intracranial aneurysms. The majority of middle cerebral artery aneurysms are treated by microsurgical clipping. Most of the classifications of aneurysms at present are based on size, location or pathology which are effective for the description but are less useful in preoperative planning and also in deciding on the technique or type of clip application. The aim of our study was to examine the morphological features of unruptured MCA bifurcation aneurysms which influence the techniques of clipping of these aneurysms and to attempt to subclassify unruptured middle cerebral artery aneurysms based on their preoperative 3D CTA and intraoperative characteristics so as to help in the intraoperative choice of technique and clip application, respectively. Preoperative 3D CT angiography and intraoperative images along with the record of technique and type of clips used for 141 unruptured MCA aneurysms operated at our center were studied retrospectively. Unruptured MCA bifurcation aneurysms could be subclassified into 5 types based on the similarities in their morphological features which influenced the techniques of clipping as recorded from their preoperative 3D CTA and intraoperative view. These types and the distinctive feature of each type are described. The various techniques of clipping are discussed based on these subgroups. The groups outlined make possible the establishment of a common technical approach to clipping within the groups. This classification, based on preoperative 3D CTA and intraoperative morphological features of the aneurysm and parent vessels, helps in the intraoperative choice of technique and type of clip application to tackle these lesions.

Preoperative Evaluation of Perigastric Vascular Anatomy by 3-Dimensional Computed Tomographic Angiography Using 16-Channel Multidetector-Row Computed Tomography for Laparoscopic Gastrectomy in Patients With Early Gastric Cancer

The purpose of this study was to evaluate the efficacy of 3-dimensional computed tomographic angiography (3D CTA) using 16-channel multidetector-row helical computed tomography (MDCT) in the preoperative visualization of laparoscopic gastrectomy for early gastric cancer. Twenty consecutive patients with early gastric cancer who underwent computed tomographic (CT) examination using 16-channel MDCT (0.625 mm x 16) before surgery were included in this study. At a rate of 4 mL/s, 2 mL/kg of 300 mg I/mL contrast material was intravenously injected. Timing for arterial phase scanning was determined by using a test bolus injection. Portal phase imaging was performed 70 seconds after the start of bolus injection. By using volume rendering and maximum intensity projection techniques, 3D CT angiograms of perigastric vessels were reconstructed from CT images of 0.625-mm thickness on computer workstations. In all cases, the left gastric artery (LGA) and the right gastric artery were correctly identified on 3D CTA, and the left gastric vein was also depicted on 3D CTA in all cases. In 2 cases, the aberrant left hepatic artery from LGA was correctly identified on 3D CTA. In 1 case, the accessory LGA from the left hepatic artery was correctly identified on 3D CTA. The variations of the veins included the left gastric vein flowing into the portal vein in 10 cases: the splenic vein in 9 and the junction of the portal and splenic veins in 1. A 3D CTA reconstructed from 16-channel MDCT images clearly revealed perigastric vascular anatomy in all cases, which is important for laparoscopic gastrectomy. Three-dimensional CTA is useful for the preoperative visualization of laparoscopic gastrectomy.

Endovascular Treatment of Traumatic Carotid- Jugular Fistula: Report of Two Cases

We report 2 patients with a traumatic carotid- jugular fistula. The first patient suffered a deep neck penetrating injury. The external carotid-jugular fistula was demonstrated by 3-dimension CT angiography (3D CTA) and digital subtraction angiography (DSA). The patient was treated with coil embolization. The second patient suffered a gun shot injury to the neck. 3D CTA and DSA revealed a common carotid-jugular fistula and a pseudoaneurysm. The common carotid-jugular fistula was treated with coil embolization in the fistula and the pseudoaneurysm was treated with stent assisted coil embolization .

CAN 3D-CT ANGIOGRAPHY (3D-CTA) REPLACE CONVENTIONAL CATHETER ANGIOGRAPHY IN RUPTURED ANEURYSM SURGERY?OUR EXPERIENCE WITH 162 CASES

In this communication, we studied whether 3D-CT angiography (3D CTA) gives us enough information for a safe operation without those from conventional catheter angiography (CCA) in patients with ruptured aneurysms. Between December 1996 and September 2005, we treated 162 consecutive patients with ruptured aneurysms in the acute stage based on 3D-CTA findings. One hundred sixty-two ruptured aneurysms, including 64 associated unruptured aneurysms, were detected using 3D-CTA. CCA was performed in nine (5.6%) of the 162 patients after 3D-CTA. They were four dissecting vertebral artery aneurysms, two basilar tip aneurysms, one basilar artery-superior cerebellar artery (BA-SCA), one previously clipped BA-SCA and one internal carotid-posterior communicating artery aneurysm. All ruptured aneurysms confirmed at surgery were treated successfully. The lack of information on CCA did not lead any neurological deficits or difficulties in the surgical procedure. 3D-CTA was of high diagnostic value compatible with CCA and yielded important information such as the configuration of the aneurysmal sac and neck, calcification in the aneurysmal wall, and the aneurysms' anatomic relation with adjacent vessels and bone structures. We suggest that 3D-CTA can replace CCA in the diagnosis of ruptured aneurysms and that most of ruptured aneurysms can be operated by using only 3D-CTA without CCA.

3D CTA reconstructions comparison in two different workstations: GE vs. Viatronix

3D CTA reconstructions comparison in two different workstations: GE vs. Viatronix

Computational Fluid Dynamics for Brain Circulation and Aneurysm with Therapeutic Devices

We analysed fluid dynamics at brain arteries having multiple inflow and out flow like Willis ring based on clinical imaging modalities. In addition, we analysed fluid dynamics with therapeutic devices like coils and stents to simulate their influences to blood flow. 3D CTA and MRA obtained three-dimensional structures of the brain vessels. The centreline was obtained from the three dimensional structure. Diameter of the blood vessels was measured by 3D CTA/MRA then smooth surfaced blood vessel models were created. For the fluid analysis, we developed a home brew software which can display parameters such as streamline, etc. In addition, our CFD (computational fluid dynamics) software can work in collaboration with a CAD (computer aided design) software which we also developed (VCAD: Volume CAD). So, therapeutic devices such as coils, balloons and stents could be placed in the models and CFD analysis could be performed placing devices in the models. The flow pattern in the complicated vascular structure could be calculated such as Willis ring which has multiple inputs like ICA, VA and multiple outlets like MCA and PCA with communicating arteries. CFD with therapeutic devices could also analysed with our system. CFD including communicating arteries will assist the simulation of parent artery occlusion. CFD with therapeutic devices is helpful not only for simulation for embolization, but will help us to design therapeutic devices under computer simulation.