CT angiography of extremity trauma

With the advent of multi-detector computed tomography, CT angiography (CTA) has rapidly become the first line imaging modality for detecting extremity arterial injuries in blunt and penetrating trauma patients. A variety of significant injuries are detected with high sensitivity and specificity. The information provided by CTAs in this patient population is often sufficient for making therapeutic decisions, such as the need for and type of surgical or endovascular interventions. Technological advances have allowed for isotropic imaging and improved quality of multi-planar and three-dimensional reformations, which aid in diagnosis and surgical planning. The rapid acquisition speed of 64 multi-detector CT scanners has facilitated integration of CTA into routine trauma CT imaging using a single contrast bolus injection.     

Optimal image reconstruction intervals for non-invasive coronary angiography with 64-slice CT

The reconstruction intervals providing best image quality for non-invasive coronary angiography with 64-slice computed tomography (CT) were evaluated. Contrast-enhanced, retrospectively electrocardiography (ECG)-gated 64-slice CT coronary angiography was performed in 80 patients (47 male, 33 female; mean age 62.1±10.6 years). Thirteen data sets were reconstructed in 5% increments from 20 to 80% of the R-R interval. Depending on the average heart rate during scanning, patients were grouped as <65 bpm (n=49) and ≥65 bpm (n=31). Two blinded and independent readers assessed the image quality of each coronary segment with a diameter ≥1.5 mm using the following scores: 1, no motion artifacts; 2, minor artifacts; 3, moderate artifacts; 4, severe artifacts; and 5, not evaluative. The average heart rate was 63.3±13.1 bpm (range 38–102). Acceptable image quality (scores 1–3) was achieved in 99.1% of all coronary segments (1,162/1,172; mean image quality score 1.55±0.77) in the best reconstruction interval. Best image quality was found at 60% and 65% of the R-R interval for all patients and for each heart rate subgroup, whereas motion artifacts occurred significantly more often (P<0.01) at other reconstruction intervals. At heart rates <65 bpm, acceptable image quality was found in all coronary segments at 60%. At heart rates ≥65 bpm, the whole coronary artery tree could be visualized with acceptable image quality in 87% (27/31) of the patients at 60%, while ten segments in four patients were rated as non-diagnostic (scores 4–5) at any reconstruction interval. In conclusion, 64-slice CT coronary angiography provides best overall image quality in mid-diastole. At heart rates <65 bpm, diagnostic image quality of all coronary segments can be obtained at a single reconstruction interval of 60%.     

Image quality and radiation exposure of coronary CT angiography in patients after coronary artery bypass graft surgery: Influence of imaging direction with 64-slice dual-source CT

BackgroundThe evaluation of native coronary arteries (NCAs) as well as coronary artery bypass graft (CABG) patency after surgery is essential. However, NCAs are often blurred in the craniocaudal scan direction because of long scan time with 64-slice CT.ObjectiveThe purpose of the study was to determine the effect of scan direction on image quality and radiation exposure in assessment of NCAs and CABGs.MethodsRetrospective analysis of 191 consecutive individuals undergoing coronary CT angiography to evaluate CABG patency using 64-slice dual source CT. A retrospectively ECG gated spiral acquisition protocol with ECG based tube current modulation and automatic adjustment of tube current to a reference of 320 mAs (“CareDose 4D”) was used. Tube current was 120 kVp. Scan direction was either cranio-caudal (CRC, n = 98) or caudo-cranial (CRC, n = 93) and the scan volume covered the entire course of all bypass grafts. Independent investigators determined quantitative image quality of the coronary arteries by evaluating contrast-to-noise ratio (CNR), radiation exposure by comparing the effective dose, and qualitative image quality through a 5 point rating scale.ResultsQuantitative image quality was not significantly different for the two groups except for the CNR of the right coronary artery which was significantly higher in patients with caudio-cranial scan direction (P = .0007). The qualitative image quality of the CaC group also was better for both NCAs and CABGs (P = .002 for NCAs and <.001 for CABGs), mostly because of the lower frequency of respiration artifacts on coronary arteries of the CaC group (P = .005). As an effect of automatic tube current adjustment, radiation dose was lower in patients with caudo-cranial scan direction (6.8 mSv vs. 9.6 mSv, p < 0.0001).ConclusionIn patients with coronary bypass grafts imaged by 64-slice dual source CT with spiral acquisition and automated tube current adjustment, a caudo-cranial scan direction results in improved image quality and reduced radiation exposure.     

Multidetector CT angiography in Takayasu arteritis

Objective

To analyse the spectrum of Takayasu's arteritis (TA) on multidetector CT angiography (MDCTA).

Materials and methods

A retrospective analysis of the MDCTA findings was performed on 15 patients clinically diagnosed as Takayasu's arteritis. The spectrum and incidence of imaging findings on CTA were compared to studies in literature on catheter angiography in Takayasu's arteritis. Laboratory parameters were available in nine patients. The disease was considered active if erythrocyte sedimentation rate (ESR) levels were elevated and ‘C’ reactive protein (CRP) was positive. An attempt was made to correlate disease activity with the imaging findings.

Results

Ascending aorta, arch of aorta and descending thoracic aorta were involved in 14 out of 15 (93%) patients. The wall thickness varied between 1 and 10 mm with maximal involvement in arch and descending thoracic aorta. Major neck vessels were involved in 11 (73%) patients with most pronounced changes seen in the brachiocephalic trunk, left common carotid artery (CCA) and left subclavian artery (SCA). Abdominal aorta and its branches were involved in all the 11 (100%) patients in whom abdominal CTA was performed. Celiac axis and SMA were involved in 10 (91%) and seven (64%) patients, respectively while renal artery stenosis was present in five (45%) patients. In six patients, ESR was elevated and CRP was positive indicating active disease. All patients in whom the laboratory parameters were available showed mural thickening in the aorta and at least one of the neck vessels except for one patient with inactive disease who had aortic mural thickening only.

Conclusion

MDCTA provides information about both the vessel wall and lumen in patients with Takayasu's disease.     

不同方向的肺部螺旋CT扫描图像质量的对比分析

目的：对比分析两种不同方向的肺部螺旋CT扫描的图像质量。方法：随机选择100例肺部扫描的患者,者人头→足和足→头两种方向扫描，两组图像按有无呼吸运动伪影，对比剂伪影来评定质量。结果：两组图像质量存在明显的差异。结论：肺部螺旋CT扫描时，采用由足→头方向扫描，能够获得更好的满足诊断要求的CT图像。     

Comparison of the image quality and radiation dose of different scanning modes in head-neck CT angiography

Objectives:To analyze and compare the radiation dose and image quality of different CT scanning modes on head-neck CT angiography.Methods:A total of 180 patients were divided into Group A and Group B. The groups were further subdivided according to different scanning modes: subgroups A1, A2, A3, B1, B2, and B3. Subgroups A1 and B1 used conventional CT protocol, subgroups A2 and B2 used the kV-Assist scan mode, and subgroups A3 and B3 used the dual-energy gemstone spectral imaging protocol. The CT dose index and dose–length product were recorded. The objective image quality and subjective image evaluation was conducted by two independent radiologists.Results:The signal-to-noise ratios, contrast-to-noise ratios, and subjective scores of subgroups A3 and B3 were higher than the other subgroups. In subgroups B1 and B2, the subjective scores of 9 patients and 12 patients were lower than 3, respectively. The subjective scores of subgroups B1 and B2 were lower than the other subgroups. There was no statistically significant difference in signal-to-noise ratios, contrast-to-noise ratios, and subjective scores between subgroups A1 and A2. The effective dose of subgroup A2 was 41.7 and 36.4% lower than that in subgroups A1 and A3, respectively (p < 0.05). In Group B, there were no statistically significant differences in CT dose indexvol, dose–length product, and ED among the subgroups (p > 0.05).Conclusion:In the head-neck CT angiography, the kV-Assist scan mode is recommended for patients with body mass index between 18.5 and 34.9 kg m⁻²; gemstone spectral imaging scanning mode is recommended for patients with body mass index ≥34.9 kg m⁻².     

64层螺旋CT冠状动脉成像质量影响因素的分析

目的:分析64层螺旋CT冠状动脉扫描中影响成像质量的各种因素。方法:对89例怀疑冠心病或冠心病复查患者进行64层螺旋CT冠状动脉检查,回顾性分析成像质量,探讨心率及心率波动对冠脉成像质量的影响,pitch值与心率的关系,替代(override)功能的应用价值,从而优化扫描参数。结果:①心率及心率波动与冠脉成像质量成负相关;②心率与扫描/重建方式及pitch值存在相互对应关系;③心率替代功能的合理使用可以提高CT冠状动脉的成像质量。结论:通过控制心率及心率波动,选择心率替代功能,采取适当的扇区扫描/重建模式可以提高图像质量和冠状动脉诊断的可靠性。     

Dose performance and image quality: dual source CT versus single source CT in cardiac CT angiography

Objective

To evaluate dose performance and image quality of 64-slice dual source CT (DSCT) in comparison to 64-slice single source CT (SSCT) in cardiac CT angiography (CTA).

Methods

100 patients examined by DSCT and 60 patients scanned by SSCT were included in this study. Objective indices such as image noise, contrast-to-noise ratio and signal-to-noise ratio were analyzed. Subjective image quality was assessed by two cardiovascular radiologists in consensus using a four-point scale (1 = excellent to 4 = not acceptable). Estimation of effective dose was performed on the basis of dose length product (DLP).

Results

At low heart rates (<70 bpm), image quality of SSCT was equivalent to that of DSCT (P > 0.05), but, at high heart rates (>70 bpm), DSCT provided robust image quality (P < 0.05). The average effective dose of SSCT was 9.3 ± 0.9 mSv at low heart rates (<70 bpm) while, the average estimated effective doses of DSCT were 9.1 ± 1.3 mSv, 8.3 ± 1.1 mSv, 7.9 ± 1.1 mSv, 6.9 ± 0.7 mSv, and 5.9 ± 1.3 mSv, corresponding to heart rates of 50-59 bpm, 60-69 bpm, 70-79 bpm, 80-89 bpm, and 90-100 bpm.

Conclusion

For cardiac CTA, both DSCT and SSCT can get good image quality at low heart rates (<70 bpm) with a similar radiation dose, but, at high heart rates (>70 bpm), DSCT is able to provide robust diagnostic image quality at doses far below that of SSCT.     

Diagnosis of intracranial haemangiopericytomas with angiography and CT scanning

Summary Twentyone primary intracranial haemangiopericytomas (HPC) were operated on from 1953 to 1983. The mean age of the 12 male and nine female patients was 38 years (17–64). Plain skull films showed well-defined bone destruction in two patients. Angiograms of 18 tumours (14 primary and four recurrent) showed the following when analysed according to the criteria of Marc et al. [4]: dual arterial supply (17/18), one-three main feeders giving rise to many irregular corkscrewlike vessels (16/18), dense, well-defined and long-lasting tumour stain (17/18), but early venous drainage rarely (1/18). The overall impression was that eight tumours appeared to be typical HPCs on angiogram. Five tumours had suggestive features, though not enough to justify specific angiographic diagnosis, and five were more like classical meningiomas. The larger tumours were more typical of HPCs, the smaller ones resembled meningiomas.CT scans of eight tumours (three primary and five recurrent) were available. The tumours were attached with a broad base to the convexity or other dural surfaces, often bilaterally. No calcifications were seen. There was little, if any, surrounding oedema. Contrast enhancement was strong and homogeneous. Four of the tumours were ring like, but the ring was thick and regular, in contrast to that in glioblastomas. The tumour margin was well-defined and smooth in three tumours, and nodular margins were seen in five; two of the latter grew extensively along dural surfaces. This sign may suggest aggressive biological behaviour. If both angiograms and CT scans are available, HPCs can be differentiated from glioblastomas and classical meningiomas, but perhaps not from anaplastic meningiomas.     

Evaluation of peripheral artery stent with 64-slice multi-detector row CT angiography: Prospective comparison with digital subtraction angiography

Purpose

To assess the accuracy of 64-slice multi-detector row computed tomography (MDCT) angiography in the evaluation of peripheral artery in-stent or peristent restenosis, with conventional digital subtraction angiography (DSA) as the reference standard.

Materials and methods

Forty-one patients (30 men, 11 women; mean age, 69.8 ± 9.2 years) with symptomatic peripheral arterial occlusive disease after peripheral artery stenting (81 stented lesions) underwent both conventional DSA and 64-slice MDCT angiography. Each stent was classified as evaluable or unevaluable, and every stent was divided into three segments (proximal stent, stent body, and distal stent), resulting in 243 segments. For evaluation, stenosis was graded as follows: 1, none or slight stenosis (<25%); 2, mild stenosis (25-49%); 3, moderate stenosis (50-74%); 4, severe stenosis or total occlusion (≥75%). Two readers evaluated all CT angiograms with regard to narrowing of in-stent or peristent restenosis by consensus. Results were compared with findings of the DSA.

Results

Of 81 stents, 62 (76.5%) were determined to be assessable. The metal artifact of the gold marker and motion artifact increased uninterpretability of the images of stents. Overall, 24 of 28 in-stent restenosis and 38 of 53 persistent restenosis were correctly detected by MDCT (85.7% and 71.7% sensitivity). In evaluable stents, 21 of 22 in-stent restenoses and 27 of 28 persistent restenosis were correctly detected (95.4% and 96.4% sensitivity). Additionally, as the grade of stenosis increases, the mean level of CT values in the stent lumina decreases linearly accordingly.

Conclusion

64-Slice MDCT has a high accuracy for the detection of significant in-stent or peristent restenosis of assessable stents in patients with peripheral artery stent implantation and therefore can be considered as a valuable noninvasive technique for stent surveillance.     

Prospective, multireader evaluation of image quality and vascular delineation of multislice CT angiography of the brain

The aim of this prospective, multireader trial was to investigate image quality and vascular delineation of cranial multislice CT angiography (MSCTA) to identify strengths and weaknesses of the method. Sixty consecutive patients underwent standardized cranial MSCTA. The mean estimated effective dose was 0.96±0.11 mSv. Three masked readers independently graded image quality parameters and vascular delineation on a 5-point scale. Vascular attenuation values and dose-length products were assessed quantitatively. Quantitative parameters were evaluated with a proportional odds regression model with bootstrapped standard errors to adjust the relevant standard errors for correlation within subjects and across readers. The non-parametric Wilcoxon sign-rank test was applied for quantitative measurements. Good to excellent ratings were observed regarding image quality parameters and vascular delineation. The delineation of veins was rated higher than that of arteries (OR 2.00). Smaller arterial segments were rated significantly less favorably than larger segments (OR up to 26.98). Moreover, the cavernous sinus, the C2 segment of the ICA and the communicating arteries demonstrated lower scores. Attenuation values were >240 HU and vessel-to-parenchyma ratios >7 in all vessels. Cranial MSCTA achieved high ratings regarding image quality and vascular delineation. Relative weaknesses were found in small arterial subsegments and in vessels in close topographical proximity to bone.     

心电编辑对提高双源CT冠脉图像质量的初步研究

目的:探讨心电编辑在改善双源CT冠脉图像质量中的作用。方法:以冠脉分支为单位,回顾性分析60例心率变异过大或心律失常患者双源CT冠脉成像编辑前后的图像质量,总结不同类型的心电编辑方法。结果:60例心率变异过大或心律失常患者,心率范围为55～269次/min,平均心率(92.8±31.9)次/min,冠脉图像编辑前后的图像质量总评分分别为2.26±1.03、3.5±0.61(t=-17.85,P=0.001);表明编辑前后图像质量的评分有统计学意义,编辑后图像质量明显改善。结论:心电编辑技术可以明显改善心率变异过大或心律失常患者双源CT冠脉成像的图像质量。     

Assessment of image quality of 64-row Dual Source versus Single Source CT coronary angiography on heart rate: A phantom study

Purpose

To assess the influence of temporal resolution on image quality of computed tomographic (CT) coronary angiography by comparing 64-row Dual Source CT (DSCT) and Single Source CT (SSCT) at different heart rates.

Methods

An anthropomorphic moving heart phantom was scanned at rest, and at 50 beats per minute (bpm) up to 110 bpm, with intervals of 10 bpm. 3D volume rendered images and curved multi-planar reconstructions (MPRs) were acquired and image quality of the coronary arteries was rated on a 5-points scale (1 = poor image quality with many artefacts, 5 = excellent image quality) for each heart rate and each scanner by 3 observers. Paired sample t-test and Wilcoxon Signed Ranks test were used to assess clinically relevant differences between both modalities.

Results

The mean image quality scores at 70, 100 and 110 bpm were significantly higher for DSCT compared to SSCT. The overall mean image quality scores for DSCT (4.2 ± 0.6) and SSCT (3.0 ± 1.1) also differed significantly (p < 0.001).

Conclusion

These initial results show a clinically relevant overall higher image quality for DSCT compared to SSCT, especially at heart rates of 70, 100 and 110 bpm. With its comparatively high image quality and low radiation dose, DSCT appears to be the method of choice in CT coronary angiography at heart rates above 70 bpm.     

Low-dose ECG-gated 64-slices helical CT angiography of the chest: evaluation of image quality in 105 patients

The purpose of this study was to evaluate image quality of low-dose electrocardiogram (ECG)-gated multislice helical computed tomography (CT) angiograms of the chest. One hundred and five consecutive patients with a regular sinus rhythm (72 men; 33 women) underwent ECG-gated CT angiographic examination of the chest without administration of beta blockers using the following parameters: (a) collimation 32×0.6 mm with z-flying focal spot for the acquisition of 64 overlapping 0.6-mm slices, rotation time 0.33 s, pitch 0.3; (b) 120 kV, 200 mAs; (c) use of two dose modulation systems, including adjustment of the mAs setting to the patient’s size and anatomical shape and an ECG-controlled tube current. Subjective and objective image quality was evaluated by two radiologists in consensus on 3-mm-thick scans reconstructed at 55% of the response rate (RR) interval. The population and protocol characteristics included: (a) a mean [±standard deviation (SD)] body mass index (BMI) of 24.47 (±4.64); (b) a mean (±SD) heart rate of 72.04 (±15.76) bpm; (c) a mean (±SD) scanning time of 18.3 (±2.73) s; (d) a mean (±SD) dose-length product (DLP) value of 260.57 (±83.67) mGy/cm; (e) an estimated average effective dose of 4.95 (±1.59) mSv. Subjective noise was depicted in a total of nine examinations (8.5%), always rated as mild. Objective noise was assessed by measuring the standard deviation of pixel values in a homogeneous region of interest within the trachea and descending aorta; SD was 15.91 HU in the trachea and 22.16 HU in the descending aorta, with no significant difference in the mean value of the standard deviations between the four categories of BMI except for obese patients, who had a higher mean SD within the aorta. Interpolation artefacts were depicted in 22 patients, with a mean heart rate significantly lower than that of patients without interpolation artifacts, rated as mild in 11 patients and severe in 11 patients. The severity of interpolation artefacts was significantly linked to a low heart rate in affected patients. The overall image quality of CT scans was rated as diagnostic in 94 patients (89.5%) while 11 examinations (10.5%) were found to be partially nondiagnostic owing to the cyclic presence of severe interpolation artefacts, which can be compensated for by additional reconstructions at a different temporal window. In these cases, interpolation artefacts could have been avoided by reducing the pitch from 0.3 to 0.2 at the expense of increased patient dose. Low-dose ECG-gated CT angiograms of the chest can be obtained in routine clinical practice with 64-slice CT technology without altering the diagnostic value of CT scans.     

CT angiography of pulmonary embolism in patients with underlying respiratory disease: impact of multislice CT on image quality and negative predictive value

Our objective was to evaluate the impact of multislice CT (MSCT) on image quality and diagnostic value of spiral CT angiograms. Over an 8-month period (January 2000 to August 2000), 134 consecutive patients, including 55 patients with underlying lung disease, underwent MSCT (group 1). Image quality and diagnostic results of CT angiograms were compared with those obtained in 125 consecutive patients, including 58 patients with underlying lung disease, evaluated with thin-collimation single slice CT (SSCT; group 2) over a similar period of time (January 1999 to August 1999). A 3-month clinical follow-up was systematically obtained in all patients who were not anticoagulated in the two groups. For a significantly longer mean z-axis coverage, the mean duration of data acquisition was significantly shorter with MSCT. The frequency of examinations devoid of motion artifacts was significantly higher in group 1 than in group 2. In the absence of significant difference in the quality of vascular enhancement, mainly coded as good or excellent, the proportion of examinations interpretable down to the subsegmental arteries was higher in group 1 (57.5%) than in group 2 (13%) ( p<0.0001). The benefits of MSCT were more marked for patients with underlying respiratory disease and did not lead to a higher detection rate of peripheral pulmonary embolism. The negative predictive values of single-slice and multislice CT were 100 and 99%, respectively. Improvement in image quality on MSCT scans accounts for the improved diagnostic accuracy of CT angiography, in particular for patients with impaired respiratory function.     

64-slice multidetector coronary CT angiography: in vitro evaluation of 68 different stents

The purpose of this study was to test a large sample of different coronary artery stents using four image reconstruction approaches with respect to lumen visualization, lumen attenuation, and image noise in 64-slice multidetector-row computed tomography (MDCT) in vitro and to provide a catalogue of currently used coronary artery stents when imaged with state-of the-art MDCT. We examined 68 different coronary artery stents (57 stainless steel, four cobalt-chromium, one cobalt-alloy, two nitinol, four tantalum) in a coronary artery phantom (vessel diameter 3 mm, intravascular attenuation 250 HU, extravascular density −70). Stents were imaged in axial orientation with standard parameters: 32x0.6 collimation, pitch 0.24, 680 mAs, 120 kV, rotation time 0.37 s. Four different image reconstructions were obtained with varying convolution kernels and section thicknesses: (1) soft, 0.6 mm, (2) soft, 0.75, (3) medium soft, 0.6, and (4) stent-optimized sharp, 0.6. To evaluate visualization characteristics of of the stent, the lumen diameter, intraluminal density and noise were measured. The high-resolution kernel offered significantly better average lumen visualization (57% ±10%) and more realistic lumen attenuation (222 HU ±66 HU) at the expense of increased noise (15.3 HU ±3.7 HU) compared with the soft and medium-soft CT angiography (CTA) protocol (p<0.001 for all). Stents with a lumen visibility of more than 66% were: Arthos pico, Driver, Flex, Nexus2, S7, Tenax complete, Vision (all 67%), Symbiot, Teneo (70%), and Radius (73%). Only ten stents showed a lumen visibility of less than 50%. Stent lumen visibility largely varies depending on the stent type. Even with the improved spatial resolution of 64-slice CT, a stent-optimized kernel remains beneficial for stent visualization when compared with the standard medium-soft CTA protocol. Using 64-slice CT and high-resolution kernel, the majority of stent products show a lumen visibility of more than 50% of the stent diameter.     

64层螺旋CT冠状动脉成像与冠状动脉造影的对比研究

目的评价64层螺旋CT冠状动脉成像诊断冠状动脉狭窄的准确性。方法 50例患者先后进行64层螺旋CT冠状动脉成像和冠状动脉造影检查,以冠状动脉造影为诊断冠状动脉疾病的"金标准",比较CT冠状动脉成像的符合率,评价64层螺旋CT冠状动脉成像诊断冠心病的准确性。结果 64层螺旋CT冠状动脉成像评价冠状动脉狭窄程度大于或等于50%的敏感性为98.6%,诊断狭窄程度小于50%的敏感性为87.0%,诊断冠状动脉狭窄的特异性为92.5%,阴性预测值为97.7%。结论 64层螺旋CT冠脉成像诊断冠状动脉狭窄有很高的准确率。     

Multidetector CT chest with bronchial and pulmonary angiography determining causes,site and vascular origin of bleeding in patients with hemoptysis

Objective

To assess the role of MDCT chest with bronchial and pulmonary angiography in determining the cause, site of bleeding, and its vascular origin in patients presenting with hemoptysis.

Materials and methods

Fifty patients suffering from hemoptysis were evaluated by MDCT with bronchial and pulmonary angiographic techniques.

Results

MDCT chest with angiography revealed the cause in 84% of cases, the site and vascular origin in 76% of cases presenting with hemoptysis.

Conclusion

MDCT of the chest with bronchial and pulmonary angiography is considered a primary noninvasive imaging modality in the evaluation of patients with hemoptysis. It also serves as a guide for other diagnostic or therapeutic procedures.