Effect of partial left ventriculectomy on left and right ventricular volumes and function as assessed with electron beam tomography: preliminary results

Our objective was to determine if left ventricular reduction surgery affects left and right ventricular volumes and function. Twenty-three patients with end-stage heart failure underwent contrast-enhanced electron beam tomographic function studies before and twice after partial left ventriculectomy (PLV). The PLV was combined with other cardiosurgical procedures in 20 of 23 patients. Left and right ventricular enddiastolic volume (LVEDV, RVEDV), stroke volume (LVSV, RVSV), ejection fraction (LVEF, RVEF), and enddiastolic diameter (LVEDD, RVEDD) were determined by manual tracing of endo- and epicardial borders at enddiastole and endsystole. Patients were scanned 31 days (±34) before and 18 days (±13) and 8 months (±4) after PLV. Mean pre- and early and late postoperative values for LVEDV, LVSV, LVEF, and LVEDD were 387.9 ml (±125.5 ml), 255.6 ml (±79.3 ml; p<0.01), and 253.7 ml (±97.8 ml; p<0.05), 79.7 ml (±25.2 ml), 74.8 ml (±17.9; n.s.), and 79.1 ml (±26.5 ml; n.s.), 21.6% (±7.3%), 31.9% (±13.4%; p<0.05), and 34.1% (±14.1%; p<0.05), and 72.0 mm (±10.6 mm), 64.3 mm (±8.5 mm; p<0.05), and 63.5 mm (±9.4 mm; p<0.05), respectively. Mean pre- and postoperative values for RVEDV, RVSV, RVEF, and RVEDD were 177.7 ml (±72.8 ml), 172.4 ml (±59.2 ml; n.s.), and 178.9 ml (±60.8 ml; n.s.), 60.3 ml (±21.6 ml), 68.8 ml (±19.9 ml; n.s.), and 78.3 ml (±25.3 ml; n.s.), 38.1% (±15.4%), 43.7% (±16.3%; p<0.05), and 45.1% (±11.2%; n.s.), and 50.4 mm (±10.9 mm), 48.1 mm (±8.7 mm; n.s.), and 48.5 mm (±9.8 mm; n.s.), respectively. The PLV may induce a significant early reduction of left ventricular volumes and improvement of biventricular function; however, our results must be judged carefully as the majority of patients in this study underwent additional cardiosurgical procedures, the contributory effect of which on the overall outcome remains unclear. Electronic Publication     

Computed tomographic ventriculography: a clinicoradiological study of 31 cases

We present 31 patients whose diagnoses were established by the aid of computed tomographic ventriculography. The indications for and diagnostic value of this method are reviewed.     

The number and distribution of computerised tomography scanners in Turkey

The goal of this study was to investigate the number and distribution of CT scanners in Turkey. Our results show 173 CT scanners in Turkey in 1994, which equals 2.9 scanners per million people. All of the scanners are located in 45 cities, where 81 % of the population resides. The other 31 cities in Turkey have no scanners. Of the 173 scanners, 103 (59.6 %) are owned by the private sector and the other 70 are owned by the public sector. Of Turkey's CT scanners, 49.2 % are located in private health centres, 21.9 % in university hospitals, 16.7 % in Ministry of Health (MOH) hospitals, 10.4 % in private hospitals and 1.8 % in social security hospitals. Received: 7 August 1998; Revision received: 13 November 1998; Accepted: 17 November 1998     

Noninvasive gadolinium-enhanced three dimensional computed tomography coronary angiography

RATIONALE AND OBJECTIVES: Although the use of gadolinium (Gd)-based contrast agents for angiographic studies of abdominal aorta, renal vasculature, and digital subtraction angiography has been reported, no studies have shown their diagnostic efficacy and image quality in coronary computed tomography angiography (CTA). The aim of this study is to evaluate the image quality of Gd-based contrast agents during coronary CTA. MATERIALS AND METHODS: A phantom study was done to evaluate the attenuation of serial dilutions of Gd and iodinated agents. This study was done on a 64-slice multirow detector CT (MDCT) scanner and e-speed scanner and CT attenuation Hounsfield units (CTHU) were compared. We evaluated 35 consecutive patients who underwent Gd-enhanced CTA. CTHU of aorta was measured at first, mid, and lowest slice levels with and without contrast administration. The image quality was graded on the basis of visualization of the coronary arteries (scale I-III; III demonstrating diagnostic image quality of the distal-most vessels). In a substudy, four patients with borderline renal insufficiency underwent CTA using Gd and iodinated contrast agents admixed in a 50:50 ratio. RESULTS: The phantom study showed that enhancement of various dilutions of Gd and iodine resulted in near identical CTHU with both e-speed and 64-slice scanners (r(2) > or = 0.997). Mean CTHU with contrast at the top slice was 116 HU, at middle slice was 125 HU, and at the lower slice was 93 (111.14 +/- 22). Quality evaluation showed 2 grade III, 9 grade II, and 24 grade I images (average quality of images 1.35). Mean CTHU was 222. CONCLUSION: Gd-enhanced contrast medium provides adequate enhancement of coronary vasculature, allowing for diagnostic evaluation of coronary arteries with new CT systems. Use of newer generations of multirow detector CT scanners should further enhance the quality of images.     

不同类型CT和MR血管成像诊断颅内动脉瘤准确率的Meta分析

目的 分析评价不同类型CT血管成像（CTA）和MR血管成像（MRA）诊断颅内动脉瘤（IAN）的准确率。 方法 检索PubMed、EMbase、Cochralle图书馆和中国知网、中国生物医学文献数据库、维普网、万方数据库,收集2018年1月以前有关不同类型CTA和MRA诊断IAN的中、英文文献,按照诊断性研究的纳入标准筛选文献,并依据诊断准确性试验质量评价工具2标准进行质量评价。采用Stata 12.0及Meta-Disc 1.4软件对纳入的文献进行Meta分析,分别比较CTA、MRA及亚组之间的合并灵敏度（SEN合并）、合并特异度（SPE合并）、诊断比值比（DOR）、合并阳性似然比（PLR合并）、合并阴性似然比（NLR合并）、验前概率和验后概率等性能指标,绘制森林图和综合受试者工作特征（SROC）曲线并计算曲线下面积（AUC）。采用Stata 12.0统计分析软件绘制Deek's漏斗图评估纳入文献的发表偏倚。通过Q检验和I2进行异质性分析。 结果 检索获得1754篇文献,最终纳入38篇临床诊断研究,包括5212例患者。Meta分析结果显示：①CTA诊断IAN的SEN合并、SPE合并、DOR、PLR合并、NLR合并、AUC、验前概率和验后概率分别为0.947（95%CI：0.926,0.963）、0.916（95%CI：0.864,0.949）、195.328（95%CI：97.367,391.847）、11.218（95%CI：6.861,18.341）、0.057（95%CI：0.040,0.082）、0.98（95%CI：0.96,0.99）、20%和74%;②MRA诊断IAN的SEN合并、SPE合并、DOR、PLR合并、NLR合并、AUC、验前概率和验后概率分别为0.935（95%CI：0.899,0.958）、0.956（95%CI：0.917,0.977）、311.421（95%CI：126.935,764.038）、21.285（95%CI：11.114,40.766）、0.068（95%CI：0.044,0.107）、0.98（95%CI：0.97,0.99）、20%和84%;③亚组分析结果显示：不同类型的CTA和MRA诊断IAN之间AUC的差异均无统计学意义。 结论 不同类型CTA与MRA均可以诊断IAN,诊断准确性均较高且基本一致,CTA和MRA均可作为诊断IAN的首选检查手段。     

Contrast timing in computed tomography: effect of different contrast media concentrations on bolus geometry

Objective

To assess the effect of low-osmolar, monomeric contrast media with different iodine concentrations on bolus shape in aortic CT angiography.

Materials and methods

Repeated sequential computed tomography scanning of the descending aorta of eight beagle dogs (5 male, 12.7 ± 3.1 kg) was performed without table movement with a standardized CT scan protocol. Iopromide 300 (300 mg I/mL), iopromide 370 (370 mg I/mL) and iomeprol 400 (400 mg I/mL) were administered via a foreleg vein with an identical iodine delivery rate of 1.2 g I/s and a total iodine dose of 300 mg I/kg body weight. Time-enhancement curves were computed and analyzed.

Results

Iopromide 300 showed the highest peak enhancement (445.2 ± 89.1 HU), steepest up-slope (104.2 ± 17.5 HU/s) and smallest full width at half maximum (FWHM; 5.8 ± 1.0 s). Peak enhancement, duration of FWHM, enhancement at FWHM and up-slope differed significantly between iopromide 300 and iomeprol 400 (p < 0.05). Except for enhancement at FWHM there were no significant differences between iopromide 300 and iopromide 370 and iopromide 370 and iomeprol 400 (p > 0.05).

Conclusions

Low viscous iopromide 300 results in a better defined bolus with a significantly higher peak enhancement, steeper up-slope and smaller FWHM when compared to iomeprol 400. These characteristics potentially affect contrast timing.     

Fibromuscular dysplasia in living renal donors: Still a challenge to computed tomographic angiography

Background

Computed tomographic angiography has become the standard evaluating method of potential living renal donors in most centers. Although incidence of fibromuscular dysplasia is low (3.5-6%), this pathology may be relevant for success of renal transplantation. The incidence of FMD in our population of LRD and reliability of CTA for detecting vascular pathology were the aims of this study.

Materials and methods

101 living renal donors, examined between 7/2004 and 9/2008 by CTA, were included in a retrospective evaluation. The examinations were carried out using a 64 Multi-detector CT (Siemens Medical Solutions, Erlangen). The presence or absence of the characteristic signs of fibromuscular dysplasia, as “string-of-beads” appearance, focal stenosis or aneurysms, were assessed and graded from mild (=1) to severe (=3). Furthermore, vascular anatomy and arterial stenosis were investigated in this study. Retrospective analysis of CTA and ultrasound were compared with operative and histological reports.

Results

Four cases of fibromuscular dysplasia (incidence 3.9%) in 101 renal donors were diagnosed by transplanting surgeons and histopathology, respectively. Three cases could be detected by CTA. In one donor even retrospective analysis of CTA was negative. Ten accessory arteries, 14 venous anomalies and 12 renal arteries stenosis due to atherosclerosis were diagnosed by CTA and could be confirmed by the operative report.

Conclusion

CTA is sufficient for detection of hemodynamic relevant stenosis and vascular anatomy. Only one patient with a mild form of FMD was under estimated. Therefore, if the CTA shows slightest irregularities which are not typical for atherosclerotic lesions, further diagnostic work up by DSA might still be necessary.     

Radiation and contrast agent doses reductions by using 80-kV tube voltage in coronary computed tomographic angiography: A comparative study

Objective

To investigate the effects of 80-kilovoltage (kV) tube voltage coronary computed tomographic angiography (CCTA) with a reduced amount of contrast agent on qualitative and quantitative image quality parameters and on radiation dose in patients with a body mass index (BMI) <23.0 kg/m².

Methods

One hundred and twenty consecutive patients with a BMI <23.0 kg/m² and a low calcium load undergoing retrospective electrocardiogram (ECG)-gated dual-source CCTA were randomized into two groups [standard-tube voltage (120-kV) vs. low-tube voltage (80-kV)]. The injection flow rate of contrast agent (350 mg I/mL) was adjusted to body weight of each patient (4.5–5.5 mL/s in the 120-kV group and 2.8–3.8 mL/s in the 80-kV group). Radiation and contrast agent doses were evaluated. Quantitative image quality parameters and figure of merit (FOM) of coronary artery were evaluated. Each coronary segment was evaluated for image quality on a 4-point scale.

Results

Compared with the 120-kV group, effective dose and amount of contrast agent in the 80-kV group were decreased by 57.8% and 30.5% (effective dose:2.7 ± 0.5vs. 6.4 ± 1.3 mSv; amount of contrast agent:57.1 ± 3.2 vs. 82.1 ± 6.1 mL; both p < 0.0001), respectively. Image noise was 22.7 ± 2.1 HU for 120-kV images and 33.2 ± 5.2 HU for 80-kV images (p < 0.0001). Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) in the proximal right coronary artery (RCA) and left main coronary artery (LMA) were all lower in 80-kV than 120-kV images (SNR in the proximal RCA: 16.5 ± 1.8 vs. 19.4 ± 2.8; SNR in the LMA: 16.3 ± 2.0 vs.19.6 ± 2.7; CNR in the proximal RCA: 19.4 ± 2.3 vs.22.9 ± 3.0; CNR in the LMA: 18.8 ± 2.4 vs. 22.7 ± 2.9; all p < 0.0001). FOM were all significantly higher in 80-kV than 120-kV images (proximal RCA: 146.7 ± 45.1 vs. 93.4 ± 32.0; LMA: 139.1 ± 47.2 vs. 91.6 ± 31.1; all p < 0.0001). There was no significant difference in image quality score between the two groups (3.3 ± 0.8 vs. 3.3 ± 0.8, p = 0.068) despite decreased SNR and CNR of coronary artery in the 80-kV group.

Conclusion

The 80-kV protocol significantly reduces radiation and contrast agent doses in CCTA in patients with a low BMI <23.0 kg/m² and a low calcium load while maintaining image quality.     

Coronary computed tomography angiography: principles of contrast material administration

A conceptual framework to approach the application of contrast media in computed tomography angiography (CTA) is discussed. With an adequate conceptual framework, the physician or technologist should be able to modify or create CTA protocols to address specific clinical and patient circumstances. The focus of this review is coronary CTA, but the basic principles are applicable to CTA in any arterial system.     

Computed tomography angiography versus digital subtraction angiography in vascular mapping for planning of microsurgical reconstruction of the mandible

The aim of this work was to compare the potential of computed tomography angiography (CTA) with that of digital subtraction angiography (DSA) in vascular mapping of the external carotid artery (ECA) branches for planning of microvascular reconstructions of the mandible with osteomyocutaneous flaps. In 15 patients CTA and DSA were performed prior to surgery. Selective common carotid angiograms were acquired in two projection for both sides of the neck. Sixteen-slice spiral computed tomography was performed with a dual-phase protocol, using the arterial phase images for 3D CTA reconstruction. Thin-slab maximum intensity projections and volume rendering were employed for postprocessing of CTA data. The detectability of the different ECA branches in CTA and DSA was evaluated by two examiners. No statistically significant differences between CTA and DSA (p=0.097) were found for identifying branches relevant for microsurgery. DSA was superior to CTA if more peripheral ECA branches were included (P=0.030). CTA proved to be a promising alternative to DSA in vascular mapping for planning of microvascular reconstruction of the mandible.     

第二代双源CT大螺距模式低辐射剂量血管成像进展

双源CT应用临床以来,在CT血管造影方面越来越显示出其独特优势,其较高的时间和空间分辨率及较快的扫描速度使获得高质量的图像成为可能。双源CT大螺距扫描模式在血管成像方面具有图像质量好、有效射线剂量低、扫描时间快等优点。笔者就第二代双源CT大螺距模式在血管成像方面的进展及临床应用价值进行综述。     

Evaluation of graft patency by computed tomographic angiography in symptom-free post-coronary artery bypass surgery patients

Background  Accelerated atherosclerosis occurs in aortocoronary saphenous vein grafts, contributing to increased morbidity and mortality rates. We estimated the prevalence of asymptomatic graft failure in patients 5 years or more after coronary artery bypass grafting (CABG) using electron-beam computed tomographic angiography (EBA). Methods and Results  EBA was performed in 45 symptom-free patients (mean age, 66±9 year; 87% male; mean time interval after CABG, 8±5 years). A total of 102 vein grafts and 37 internal mammary artery grafts were evaluated. Patients with graft stenosis or occlusion on EBA underwent myocardial perfusion scintigraphy and invasive angiography. Six grafts were unevaluable by EBA. Twenty patients had evidence of graft stenosis or occlusion on EBA. Of 20 asymptomatic patients with graft disease, 17 (85 %) had abnormal myocardial perfusion, with moderate to severe reversible ischemia occurring in one third of subjects. Fourteen occluded and eleven stenosed vein grafts were correctly diagnosed by EBA. There were 2 false-positive EBA diagnoses of graft stenosis, resulting in a 100 % positive predictive accuracy for detecting graft occlusion and 85% positive predictive accuracy for detecting graft stenosis. All occluded internal mammary artery grafts (n=3) were accurately diagnosed. Conclusion  Computed tomographic coronary angiography permits reliable identification of by pass graft stenoses and occlusion in symptom-free patients more than 5 years after CABG. Future studies are needed to assess the prognostic benefit of early detection of graft disease and intervention in asymptomatic patients The study was supported by research grants from the Harrow Cardiovascular Research Trust     

Short term,high dose corticosteroids in computed tomographic staging of experimental brain abscess

Summary A short term, high dose corticosteroid treatment protocol was investigated to determine its clinical utility in staging an experimental brain abscess. Corticosteroids were shown to decrease the degree of contrast enhancement of brain abscess 12 h after administration but the magnitude of the effect was not consistent enough to be clinically useful in staging. The corticosteroid effect progressively diminished as the inflammatory lesion encapsulated over time. This effect emphasized that a decreasing ring diameter and not diminished contrast enhancement should be the CT criterion for brain abscess resolution.Supported by NIH Grant 1 RO 1 NS 16404-02     

Image-guided microneurosurgical management of small cerebral arteriovenous malformations: the value of navigated computed tomographic angiography

In small arteriovenous malformations (AVM) with large hematomas, surgery remains the main therapeutic option. However, intraoperative identification of the AVM, feeders, and draining veins could be difficult in the environment of substantial intracerebral blood. In those selected cases, we use navigated computed tomographic angiography (CTA) for the microneurosurgical management. It is our objective to report our initial experiences. Prior to operation a conventional CTA with superficial skin fiducials placed on a patients head was acquired for diagnostic and neuronavigation purposes. Image data were transferred to a neuronavigation device with integrated volume rendering capacities which allows a three-dimensional reconstruction of the vascular tree and the AVM to be created. In all patients the AVM was removed successfully after having been localized with CTA-based neuronavigation. Navigated CTA is helpful for the operative management of small AVMs with large hematomas. The technique allows feeding arteries to be distinguished from draining veins thereby allowing the nidus of the AVM to be identified despite the presence of substantial intracerebral blood. CTA can be easily implemented into commercial neuronavigation systems.     

Effect of cardiac function on aortic peak time and peak enhancement during coronary CT angiography

Purpose

To examine the manner in which cardiac function affects the magnitude and timing of aortic contrast enhancement during coronary CT angiography (CTA).

Materials and methods

Twenty-nine patients (21 men, 8 women; mean age, 64.4 ± 13.4 years; mean weight, 59.4 ± 10.3 kg) underwent measurement of cardiac output within 2 weeks of coronary CTA. The cardiac output of each patient was measured by the thermodilution technique and the cardiac index was calculated from the body surface area. During coronary CTA, attenuation of the descending aorta was measured at the workstation every 3 s. The aortic peak time (APT) and aortic peak enhancement (APE) of each patient were calculated. Pearson's correlation coefficient analysis was used to investigate the relationships between the cardiac output or cardiac index and APT or APE. Furthermore, the relationship between patient factors or parameters on test bolus injection and APT or APE was also evaluated.

Results

The range of cardiac output, cardiac index, APT, and APE was 1.55-10.46 L/min (mean: 4.77 ± 2.13), 1.11-5.30 L/(min-m²) (mean: 3.28 ± 1.08), 25-51 s (mean: 38.3 ± 7.5), and 273.1-598.1 HU (mean: 390.4 ± 72.1), respectively. With an increase in the cardiac index, both APT (r = −0.698, p < 0.0001) and APE (r = −0.573, p = 0.0009) decreased. There were significant correlations between the patient body weight and APT and APE with the test bolus injection, and with APT and APE during coronary CTA.

Conclusion

The APT and APE during coronary CTA are closely related to cardiac function.     

Multiphase contrast medium injection for optimization of computed tomographic coronary angiography

RATIONALE AND OBJECTIVES: Electron beam angiography is a minimally invasive imaging technique. Adequate vascular opacification throughout the study remains a critical issue for image quality. We hypothesized that vascular image opacification and uniformity of vascular enhancement between slices can be improved using multiphase contrast medium injection protocols. MATERIALS AND METHODS: We enrolled 244 consecutive patients who were randomized to three different injection protocols: single-phase contrast medium injection (Group 1), dual-phase contrast medium injection with each phase at a different injection rate (Group 2), and a three-phase injection with two phases of contrast medium injection followed by a saline injection phase (Group 3). Parameters measured were aortic opacification based on Hounsfield units and uniformity of aortic enhancement at predetermined slices (locations from top [level 1] to base [level 60]). RESULTS: In Group 1, contrast opacification differed across seven predetermined locations (scan levels: 1st versus 60th, P < .05), demonstrating significant nonuniformity. In Group 2, there was more uniform vascular enhancement, with no significant differences between the first 50 slices (P > .05). In Group 3, there was greater uniformity of vascular enhancement and higher mean Hounsfield units value across all 60 images, from the aortic root to the base of the heart (P < .05). CONCLUSIONS: The three-phase injection protocol improved vascular opacification at the base of the heart, as well as uniformity of arterial enhancement throughout the study.