Rationale and Objectives: Selecting the optimal phase for coronary artery evaluation can be challenging, especially at higher heart rates, given that the optimal phase may differ for each of the coronary arteries. This study aimed to evaluate a novel vessel-specific algorithm which automatically outputs the minimum motion phase per coronary artery.Materials and Methods: The study included 44 patients who underwent 256-slice cardiac computed tomography for evaluation of chest pain. End-systolic and mid-diastolic minimal motion phases were automatically calculated by a previously validated global motion algorithm and by a new vessel-specific algorithm which calculates the minimum motion for each of the three main coronary arteries, separately. Two readers blindly evaluated all coronary segments for image quality. Median scores per coronary artery were compared by the Wilcoxon signed rank test.Results: The variation, per patient, between the optimal phases of the three coronary arteries was 5.0 +/- 4.5% (1%-22%) for end systole and 4.8 +/- 4.1% (0%-19%) for mid diastole. The mean image quality scores per coronary artery were 4.0 +/- 0.61 for the vessel-specific approach and 3.80 +/- 0.69 for the global phase selection (P < .001). Overall, 46 of 122 arteries had a better score with the vessel-specific approach and five with the standard global approach. Interreader agreement was substantial (k = 0.72).Conclusions: This study has shown that multiple phases are required to ensure optimal image quality for all three coronary arteries and that a vessel-specific phase selection algorithm achieves superior results to the standard global approach.

Objective: This study evaluated the changes of the aortic diameter at the suprarenal and infrarenal segment after open repair (OR) and endovascular repair (EVAR) of abdominal aortic aneurysms (AAAs).Methods: This was a retrospective analysis of all patients undergoing AAA repair between 1997 and 2008. Inclusion criteria were at least 3 months of follow-up at our institution, elective aneurysm repair, and absence of false, mycotic, or inflammatory aneurysms. For EVAR, standard computed tomography (CT) scans from follow-up were used; in the OR group, CT scans performed for unrelated nonvascular indications were used. Diameters of the aorta were measured at the first slice below the lowest renal artery and at the first slice above the highest renal artery. A 2-mm change was defined as measurable aortic neck dilatation.Results: Inclusion criteria were met by 46 patients in the OR group and 103 in the EVAR group. After a follow-up of 34.1 months (range, 5.5-131.7 months) in the OR group and 39.4 months (range, 3-108.9 months) in the EVAR group, the mean changes were 1.75 +/- 3.50 mm (OR) and 0.9 +/- 2.3 mm (EVAR; P = .305) in the suprarenal diameters and 0.8 +/- 2.9 mm (OR) and 1.2 +/- 2.5 mm (EVAR; P = .311) in the infrarenal diameters. The absolute suprarenal vs infrarenal sizes were 29.7 +/- 7.1 and 28.7 +/- 6.8 mm in the OR group and 28.7 +/- 3.2 and 28.5 +/- 3.6 mm, respectively, in the EVAR group (suprarenal, P = .749; infrarenal, P = .273). Increase of the aortic diameter >2 mm, defined as aortic neck dilatation, was found in 23 of 103 EVAR patients (22.3% +/- 0.862%), and in nine of 46 OR patients (19.57% +/- 0.484%; P = .870). Increase in the suprarenal change >2 mm occurred in 21 of 103 EVAR patients (20.39% +/- 1.04%) and in 14 of 46 OR patients (30.4% +/- 0.446%; P = .260). Reintervention rate of patients with an increase >2 mm was 31% (seven of 23) in EVAR and 11.1% (one of nine) in the OR group (P = .386).Conclusions: The AAA groups treated with EVAR or OR demonstrated similar increases of aneurysmal neck diameters. This suggests that aortic neck dilatation may be caused by a natural progression of the disease rather than by deviating therapeutic strategies. (J Vasc Surg 2012;55:929-34.)

Purpose To evaluate the feasibility of MRI for static and dynamic assessment of the deployment of thoracic aortic stent grafts after emergency implantation in trauma patients. Methods Twenty patients initially presenting with a rupture of the thoracic aorta were enrolled in this study. All patients underwent thoracic endovascular aortic repair (TEVAR). The deployment of the implanted stent graft was assessed by CTA and MRI, comprising the assessment of the aortic arch with and without contrast agent, and the assessment of the motion of the stent graft over the cardiac cycle. Results The stent graft geometry and motion over the cardiac cycle were assessable by MRI in all patients. Flow-mediated signal variations in areas of flow acceleration could be well visualised. No statistically significant differences in stent-graft diameters were observed between CT and MRI measurements. Conclusion MRI appears to be a valuable tool for the assessment of thoracic stent grafts. It shows similar performance in the accurate assessment of stent-graft dimensions to the current gold standard CTA. Its capability of providing additional functional information and the lack of ionising radiation and nephrotoxic contrast agents may make MRI a valuable tool for monitoring patients after TEVAR.

Purpose: To evaluate aortic neck changes, specifically aortic neck dilatation, over a 10-year period in patients undergoing endovascular aneurysm repair (EVAR) for abdominal aortic aneurysm.Methods: All patients who underwent elective EVAR at our institution from 1998 through 2007 were analyzed retrospectively. Among these, 103 patients (96 men; mean age 71 years, range 35-84) who received the 3 most frequently implanted self-expanding stent-grafts (35 Talent, 39 Excluder, and 29 Zenith) and had a minimum 3-month imaging follow-up at our department were selected for this study. All diameters were measured perpendicular to the centerline of flow on computed tomography; baseline data were derived from the first postoperative scan. Stent-graft migration was measured from the lowermost renal artery to the first strut of the stent-graft. Based on intra-and interobserver error measurements, a minimum change of 2 mm defined aortic neck dilatation.Results: During a mean follow-up of 39.4 months (range 3-108.8), infrarenal aortic neck dilatation (>2 mm) was found in 10 patients (28.6%, 95% CI 14.6-46.3) in the Talent group, 4 (10.3%, 95% CI 2.9-24.2) in the Excluder group, and 9 (31.0%, 95% CI 15.3-50.8) in the Zenith group (p=0.299). In 7 (31%) of the 23 patients with neck dilatation, additional therapy was necessary. Suprarenal changes were found in 6 patients (17.1%, 95% CI 6.6-33.6), 8 patients (20.5%, 95% CI 9.3-36.5), and 5 patients (17.2%, 95% CI 5.8-35.8), respectively (p=0.218). Stent-graft migration >2 mm was seen in 2 (1.9%) of the 103 patients in follow-up. The overall endoleak rates were 37.1% for Talent, 30.8% for Excluder, and 37.9% for Zenith (p>0.05). Two patients were converted to open repair owing to Talent stent-graft migration and persistent type I leak (Zenith). The overall reintervention rate was 13.6% (13/103).Conclusion: Only a small number of the patients treated with self-expanding stent-grafts show notable infrarenal aortic neck dilatation, which does not appear to be related to the stent-graft model. Almost all cases of aortic neck dilatation exceeded the percentage of oversizing; less than a third of patients with aortic neck dilatation required therapy. J Endovasc Ther. 2010;17:677-684

To compare image quality and effective radiation dose for prospectively gated axial CT coronary angiography on 64- and 256-slice CT.

The purpose of this study was to evaluate the potential clinical value of coronary plaque imaging with a new generation CT scanner and the interobserver variability of coronary plaque assessment with a new semiautomatic plaque analysis application. Thirty-five isolated plaques of the left anterior descending coronary artery from 35 patients were evaluated with a new semiautomatic plaque analysis application. All patients were scanned with a 256-slice MDCT scanner (Brilliance iCT, Philips Healthcare, Cleveland OH, USA). Two independent observers evaluated lesion volume, maximum plaque burden, lesion CT number mean and standard deviation, and relative lesion composition. We found 10 noncalcified, 16 mixed, and 9 calcified lesions in our study cohort. Relative interobserver bias and variability for lesion volume were −37%, −13%, −49%, −44% and 28%, 16%, 37%, and 90% for all, noncalcified, mixed, and calcified lesions, respectively. Absolute interobserver bias and variability for relative lesion composition were 1.2%, 0.5%, 1.5%, 1.3% and 3.3%, 4.5%, 7.0%, and 4.4% for all, noncalcified, mixed, and calcified lesions, respectively. While mixed and calcified lesions demonstrated a high degree of lesion volume interobserver variability, noncalcified lesions had a lower degree of lesion volume interobserver variability. In addition, relative noncalcified lesion composition had a very low interobserver variability. Therefore, there may a role for MDCT in serial noncalcified plaque assessment with semiautomatic analysis software.

Zusammenfassung Bypassoperationen am offenen Herzen werden als Standardtherapie bei fortgeschrittener koronarer Herzkrankheit durchgeführt. Ziel eines solchen Eingriffes ist es, Engstellen der Herzkranzgefäße mit Gefäßtransplantaten zu überbrücken. Eine der Herausforderungen während der Operation ist die optimale Positionierung des Bypasses auf dem erkrankten Gefäß. Um den Chirurgen bei dieser Aufgabe zu unterstützen, wurden im Rahmen des Cardio-Pointer Projekts Verfahren für computergestützte Bypasschirurgie am offenen Herzen entwickelt, die die intraoperative Navigation mit einem Zeigeinstrument (Cardio-Pointer) zu einer präoperativ geplanten optimalen Bypassstelle sowohl am schlagenden als auch am stillgelegten Herzen ermöglichen. Das entwickelte Gesamtsystem wurde an zwölf Patienten im Rahmen einer klinischen Studie evaluiert.

Purpose: The purpose of this study was to compare planimetric aortic valve area (AVA) measurements from 256-slice CT to those derived from transesophageal echocardiography (TEE) and cardiac catheterization in high-risk subjects with known high-grade calcified aortic stenosis.Methods and materials: The study included 26 subjects (10 males, mean age: 79 +/- 6; range, 61-88 years). All subjects were clinically referred for aortic valve imaging prior to percutaneous aortic valve replacement from April 2008 to March 2009. Two radiologists, blinded to the results of TEE and cardiac catheterization, independently selected the systolic cardiac phase of maximum aortic valve area and independently performed manual CT AVA planimetry for all subjects. Repeated AVA measurements were made to establish CT intra-and interobserver repeatability. In addition, the image quality of the aortic valve was rated by both observers. Aortic valve calcification was also quantified.Results: All 26 subjects had a high-grade aortic valve stenosis (systolic opening area <1.0 cm(2)) via CT-based planimetry, with a mean AVA of 0.62 +/- 0.18. In four subjects, TEE planimetry was precluded due to severe aortic valve calcification, but CT-planimetry was successfully performed with a mean AVA of 0.46 +/- 0.23 cm(2). Mean aortic valve calcium mass score was 563.8 +/- 526.2 mg. Aortic valve area by CT was not correlated with aortic valve calcium mass score. A bias and limits of agreement among CT and TEE, CT and cardiac catheterization, and TEE and cardiac catheterization were -0.07 [-0.37 to 0.24], 0.03 [-0.49 to 0.55], 0.12 [-0.39 to 0.63] cm(2), respectively. Differences in AVA among CT and TEE or cardiac catheterization did not differ systematically over the range of measurements and were not correlated with aortic valve calcium mass score.Conclusion: Planimetric aortic valve area measurements from 256-slice CT agree well with those derived from TEE and cardiac catheterization in high-risk subjects with known high-grade calcified aortic stenosis. (C) 2010 Elsevier Ireland Ltd. All rights reserved.

Rationale and Objectives. The aim of this study was to investigate whether a respiratory biofeedback system could increase navigator efficiency and maintain image quality compared to conventional respiratory-gated magnetic resonance coronary angiography (MRCA).Materials and Methods. Eighteen healthy volunteers underwent MRCA using three different respiratory-gating protocols. A conventional expiratory free-breathing (FB) sequence was compared to two approaches using navigator echo biofeedback (NEB), a midinspiratory approach (NEBin) and an expiratory approach (NEBex). Navigator data reflecting the position of the diaphragm relative to a 3-mm gating window were made available to the subject using a video projector in combination with a Plexiglas screen and mirror goggles. Image quality was graded by two radiologists in consensus using a visual score ranging from I (not visible) to 4 (excellent vessel depiction).Results. The NEB approaches improved navigator efficiency (71.1% with NEBex and 68.0% with NEBin vs 42.2% with FB), thus reducing total imaging time. This difference was statistically significant (P-NEBin.007; P-NEBex, =.001). Image quality in the NEBex group was comparable to that in the FB group (median score, 2.44 vs 2.52), but it proved to be significantly lower (median score, 1.94 vs 2.52) for the right coronary artery and the left anterior descending coronary artery in the NEBin group.Conclusion. NEB maintains image quality and significantly increases navigator efficiency, thereby decreasing total imaging time by about 40% compared to a conventional FB acquisition strategy.

OBJECTIVE As diffusion-weighted imaging is increasingly implemented into routine protocols of abdominal MRI, abnormal findings in expected and unexpected locations become more common. The aim of our retrospective study was to investigate the specificity of restricted diffusion in differentiation of benign from malignant abdominal disease. MATERIALS AND METHODS Two hundred thirty consecutively registered patients underwent abdominal MRI including diffusion-weighted imaging (single-shot spin-echo echo-planar sequence) with b values of 0, 150, 500, and 1,000 s/mm(2). Lesions were detected by two blinded readers using only the images with a b value of 1,000 s/mm(2), and representative apparent diffusion coefficients were measured. Lymph nodes were not documented. RESULTS Fifty-two of the 230 patients had a total of 55 lesions with restricted diffusion (23.9%). The mean apparent diffusion coefficient was 809 mm(2)/s. Forty-three lesions (78.2%) were malignant. The 12 benign lesions were liver hemangioma, liver adenoma, autoimmune pancreatitis, pancreatic teratoma, two abscesses, three cases of inflammatory bowel wall thickening due to Crohn's disease, Bartholin cyst, hemorrhagic ovarian cyst, and renal Rosai-Dorfman disease. CONCLUSION Restricted diffusion is generally considered to be associated with malignant tumors because of the high cellularity of these tumors. However, in interpretation of diffusion-weighted images, it should be kept in mind that a number of benign lesions, as many as 22% in our cohort, can exhibit restricted diffusion on images with high b values, thus mimicking malignant lesions.

Purpose: In this study, we investigated the influence of sublingual nitroglycerine (NTG) on the peripheral diameter, intraluminal contrast agent density, and image quality of coronary arteries during computed tomography coronary angiography (CTCA). Materials and Methods: Thirty patients with sublingual NTG application were matched to 30 patients without NTG. The diameters of the left anterior descending coronary artery (LAD), the left circumflex coronary artery and the right coronary artery were measured at 1-, 4-, and 8-cm length of each vessel as well as the intraluminal contrast agent density along the LAD. Vessel diameters and contrast attenuation at 4 and 8 cm were referenced against the values at 1 cm and processed as percentage reduction. Image quality of the posterior descending artery was assessed subjectively by 2 independent observers. Results: The percentage of peripheral vessel diameter reduction and the peripheral attenuation of contrast agent density for all measured coronary arteries was significantly smaller in the group with NTG administration. The image quality of the posterior descending artery was significantly higher in the group with NTG. Conclusions: Sublingual administration of NTG before CTCA results in improved diagnostic image quality because of a significant dilatation and improved intraluminal contrast agent density of the peripheral vessels.

Open heart bypass surgery is the standard treatment in advanced coronary heart diseases. For an effective revascularization procedure, optimal placement of the bypass is very important. To accelerate the intraoperative localization of the anastomosis site and to increase the precision of the procedure, a concept for computer assistance in open heart bypass surgery has been developed comprising the following steps: 1. Preprocedural planning: A patient-specific coronary map with information on vessel paths and wall plaque formations is extracted from a multi-slice computed tomography (MSCT). On this basis, the heart surgeon and the cardiac radiologist define the optimal anastomosis site prior to surgery. 2. Intraoperative navigation: During surgery, data are recorded at the beating heart using a stereo camera system. After registering the pre- and intraoperative data sets, preprocedural information can be transferred to the surgical site by overlaying the coronary map and the planned anastomosis site on the live video stream. With this visual guidance system, the surgeon can navigate to the planned anastomosis site. In this work, the proposed surgical assistance system has been validated for the left anterior descending coronary artery (LAD). The accuracy of the registration mechanism has been evaluated in retrospective on patient data sets and the effects of breathing motion were quantified. The promising results of the retrospective evaluation led to the in-vivo application of the computer assistance system during several bypass grafting procedures. Intraoperative navigation has been performed successfully and postoperative evaluation confirms that the bypass grafts were accurately positioned to the preoperatively planned anastomosis sites.

During open heart coronary artery bypass grafting (CABG), optimal placement of the bypass graft on the diseased target vessel is of utmost importance. To assist the heart surgeon in this matter, a surgical navigation system has been developed. The concept includes preprocedural planning of the optimal position for the distal anastomosis (surgical target) on the target vessel and intraoperative image-guided navigation to that position. Navigation is enabled by registration of pre- and intraoperative data. The registration mechanism was validated retrospectively. Promising results justified subsequent intraoperative live application of the system during 11 open heart CABG surgeries enabling navigation on 21 target vessels on the anterior, lateral and inferior wall of the heart. In each case, the employed registration mechanism ensured good alignment of preoperatively planned and intraoperatively identified surgical targets. The system is very well applicable for in-vivo navigation and allows for bypass grafting precisely at a preoperatively planned position.

Purpose of this study was the evaluation of the thoracic aortic wall thickness as a potential identifier of patients at increased risk for future cardiac events. Thoracic aortic wall thickness was measured with MDCT in 160 patients. The CT-scans were implemented as non-invasive coronary angiography studies. Relationships between aortic wall thickness, sex, age, major risk factors and atherosclerotic plaque burden of the coronary arteries were explored. Higher values of maximum aortic wall thickness of the descending aorta (women P = 0.02, men P = 0.01) were found in patients with coronary atherosclerosis, compared to patients with same gender but excluded atherosclerosis. Aortic wall thickness of the mid-portion of the descending aorta of 3.0 mm is associated with coronary artery disease (CAD) with a specificity of 96.6% (sensitivity 27.5%) and a positive predictive value (PPV) of 93.3%. For patients with two or more major risk factors and a maximum wall thickness of equal or more than 2.6 mm we found a PPV of 100%. We conclude that measurements of maximum wall thickness of the descending aorta are a potential tool for detecting patients with coronary atherosclerosis. The potential effect of combining measurements of aortic wall thickness at routine chest CT studies with a possible cardiovascular screening is substantial and merits further study.

Coronary artery bypass grafting (CABG) is the standard treatment for advanced coronary artery diseases (CAD). Optimal placement of the bypass graft on the diseased vessel is very important. To assist the surgeon in this matter, a computer assistance system has been developed facilitating navigation on the heart surface. After retrospective validation on patient data sets yielded good results, the system was successfully applied for in-vivo navigation on the front side of the heart during several CABG procedures. Postoperative evaluation confirmed that intraoperative navigation has been performed with adequate accuracy.

Coronary artery bypass grafting (CABG) is the most commonly performed type of open heart surgery. For an effective revascularisation procedure, the positioning of the bypass graft (distal anastomosis) is of utmost importance. To assist the surgeon in this matter, a surgical navigation system for the open heart has been developed. Prior to surgery, the optimal distal anastomosis site is planned for each diseased target vessel on the basis of cardiac MSCT (multi-slice computed tomography) data. Intraoperative surgical assistance is provided by image-guided navigation to the planned positions. To enable navigation on the arrested heart, registration of preand intraoperative modalities is required. The registration mechanisms for the arrested heart were validated retrospectively on patient data from CABG procedures. The promising results led to subsequent intraoperative live application of the system during 11 open heart CABG surgeries enabling navigation at the arrested heart on a total of 21 target vessels situated anywhere on the heart surface. In each case, the employed registration method ensured good alignment of preoperatively planned and intraoperatively identified surgical target. The system is very well applicable for in-vivo navigation and allows for bypass grafting precisely at a preoperatively planned position.

The current evolution of CT is driven by cardiac imaging. Reliable and robust diagnostic performance for this application is crucially dependent on temporal resolution. Very different approaches are taken by the major vendors. Rotational time is unanimously accelerated and has currently arrived at 270 msec per rotation, but today's scanners barely meet the requirement of 65 msec per image at higher heart rates. Another industry focus relates to the detector with more and more rows added. A complete cardiac dataset can nowadays be acquired in less than 6 sec with detector sizes > 8 cm in z-direction. This renders the method less susceptible to arrhythmia and heart rate variations. The best, currently available, solution operates at a detector size of 16 cm covering the heart at a single rotation, albeit compromising on temporal resolution. The technical evolution has also realized that dose exposure needs to be decreased substantially for a widespread application. This has culminated in a trend away from spiral acquisitions to prospective axial rotations. This allows to reduce dose exposure by as much as 80%. Provided that the current speed of technical improvements will persist it is foreseeable that most invasive angiograms will be replaced in the upcoming years. CT equipped with future detector technology has the potential to become the prime imaging modality for cardiovascular medicine.

Many patient-related and injection-related factors can affect the magnitude and timing of intravenous contrast agent attenuation. MDCT, with its dramatically shorter image acquisition times, permits images with a much better utilization of the peak contrast attenuation. High iodine concentrations of contrast media and newer scanner generations are mutually conditional. The very high iodine flux rates required by cutting-edge angiographic applications can be met by low concentration iodine agents only at very high flow rates resulting in high volumes administered. Sporadic failure, though, is unpreventable at the current stage of development. This is simply due to the fact that the patient’s cardiac output is not known prior to scan initiation in most cases. MDCT is a powerful and continuously evolving technology for noninvasive imaging. CA administration is an integral part of this evolution and needs to be continuously adopted and optimized to take full advantage of this technology. A basic understanding of physiologic and pharmacokinetic principles, as well as an understanding of the effects of injection parameters on vascular and parenchymal enhancement, allows the development of optimized contrast agent delivery protocols for current and future MDCT. Scan timing will only then succeed to acquire images at peak enhancement in the tissue of interest.