Attenuation-based characterization of coronary atherosclerotic plaque: Comparison of dual source and dual energy CT with single-source CT and histopathology

Objective

To compare different CT acquisition techniques regarding for attenuation-based characterization of coronary atherosclerotic plaques using histopathology as the standard of reference.

Materials and methods

In a post mortem study 17 human hearts were studied with dual-source CT (DSCT) and dual energy CT (DECT) mode on a DSCT as well as with 16-slice single-source CT (SSCT). At autopsy, atherosclerotic lesions were cut at 5 μm sections. Histopathologic classification of the plaques according to the American Heart Association (AHA) criteria was performed by two pathologists. Attenuation values of all plaques were measured in DSCT, DECT and SSCT studies, respectively and classified based on attenuation according to modified AHA criteria.

Results

58 coronary plaques were identified at autopsy. Regardless of the CT technique only 52/58 plaques were found at CT (sensitivity = 89.6%). There was no significant difference between the mean attenuation values of different plaque types between DSCT, DECT, and SSCT: type IV: 11 HU/8 HU/19 HU; type Va: 44 HU/45 HU/52 HU; type Vb: 1088 HU/966 HU/1079 HU). The sensitivity for correct classification varied depending on the plaque type (type II = 0%, type III = 0%, type IV = 43%, type Va = 58%, Vb = 97%).

Conclusion

Independent of the used acquisition technique, SSCT, DSCT and DECT show similar results for attenuation-based characterization of atherosclerotic coronary plaques.     

Role of dual energy computed tomography in management of different renal stones

Aim and objectives

To evaluate the role of dual energy computed tomography in renal stones.

单次对比增强双源CT双能量心脏成像的初步应用研究

目的评价单次对比增强双源CT双能量心脏成像的可行性和初步应用。方法30例受检者行双源CT双能量心脏成像,分别有6例病人于1周内进行了DSA或SPECT检查。2名有经验的影像诊断医师对所有冠状动脉影像质量和碘图进行分段评分,并对冠状动脉狭窄节段与碘图分布情况进行对照分析。结果冠状动脉成像可诊断率为100%（300/300）,影像质量评分均值为4.68±0.57。30例病人中8例共10个节段发现壁冠状动脉,12例共32个节段冠状动脉发现粥样硬化性斑块,其中20个节段狭窄≥50%,12个节段狭窄≤50%;3例病人的双能量CT（DECT）冠状动脉成像与DSA所见一致。融合碘图有15例共37个节段发现灌注异常,其中28个节段供血支冠状动脉狭窄,9个节段未见冠状动脉狭窄（其中3个节段SPECT检查为阴性）。结论心率合适的情况下,单次对比增强双源CT双能量成像可获得优良的冠状动脉和心肌灌注影像,有一定的临床应用潜力,但尚需深入研究。     

Characterization of coronary atherosclerosis by dual-source computed tomography and HU-based color mapping: a pilot study

To assess HU-based color mapping for characterization of coronary plaque, using intravascular ultrasound virtual histology (IVUS-VH) as a standard of reference. Dual-source computed tomography and IVUS-VH were prospectively performed in 13 patients. In five lesions, HU thresholds of the color-coding software were calibrated to IVUS-VH. In a 15-lesion verification cohort, volumes of vessel, lumen and plaque or percentages of lipid, fibrous and calcified components were obtained through use of pre-set HU cut-offs as well as through purely visual adjustment of color maps. Calibrated HU ranges for fatty or fibrous plaque, lumen and calcification were -10–69, 70–158, 159–436 and 437+. Using these cut-offs, HU-based analysis achieved good agreement of plaque volume with IVUS (47.0 vs. 51.0 mm³). Visual segmentation led to significant overestimation of atheroma (61.6 vs. 51.0 mm³; P = 0.04) Correlation coefficients for volumes of vessel, lumen and plaque were 0.92, 0.87 and 0.83 with HU-based analysis or 0.92, 0.85 and 0.71 with visual evaluation. With both methods, correlation of percentage plaque composition was poor or insignificant. HU-based plaque analysis showed good reproducibility with intra-class correlation coefficients being 0.90 for plaque volume and 0.81, 0.94 or 0.98 for percentages of fatty, fibrous or calcified components. With use of optimized HU thresholds, color mapping allows for accurate and reproducible quantification of coronary plaque. There is no conflict of interest.     

Future of cardiac computed tomography

Coronary computed tomography angiography (CCTA) has become an integral tool in the noninvasive diagnostic workup of patients with suspected coronary artery disease in both elective and emergency settings. Today, it represents a mature technique providing accurate, non-invasive morphological assessment of the coronary arteries and atherosclerotic plaque burden. Iterative reconstruction algorithms, low kV imaging, and single-heart beat acquisitions hold promise to further reduce dose requirements and improve the safety and robustness of the technique in several circumstances including imaging of heavily calcified vessels, patients with morbid obesity or irregular heart rates, and assessment in the emergency setting. However, it has become clear over recent years that cardiac radiologists need to take further steps towards the development and integration of functional imaging with morphological CCTA assessment to truly provide a comprehensive evaluation of the heart. Computed tomography myocardial perfusion imaging, including both dynamic and static dual-energy approaches, has demonstrated the ability to directly assess and quantify myocardial ischemia with simultaneous CCTA acquisition with a reasonable contrast medium volume and radiation dose delivered to the patient. In order to promote CCTA in the clinical and research environments, radiologists should prepare to embrace the change from morphological to functional imaging, furnishing all the necessary resources and information to referring clinicians.     

双源CT双能量碘图评价主动脉病变肾灌注水平

目的:探讨双源CT双能量成像碘图评价主动脉病变患者肾灌注水平的临床应用价值.方法:10例主动脉病变患者行CT血管成像(CTA)后行双能量扫描,应用Liver VNC程序,重建肾灌注碘图,测量双肾实质正常灌注及低灌注感兴趣区的CT值、碘浓度、对比增强率及脂肪分类.结果:10例受检者CTA共扫描20侧肾脏,其中6侧灌注异常减低.双能量碘图检查结果与CTA一致;肾脏低灌注区的碘浓度和对比增强率低于对照侧,差异有统计学意义(t=5.08,P＜0.05;t=4.16,P＜0.05);0.5融合图像低灌注区CT值低于对照侧,差异有统计学意义(t=6.20,P＜0.05);肾低灌注区与对照侧的脂肪分类差异无统计学意义(t=1.94,P=0.08).结论:应用双能量碘图可直观显示肾灌注水平,测量感兴趣区CT值、碘浓度和对比增强率等定量指标可反映肾灌注水平,与CTA联合应用有助于准确评价主动脉病变患者的肾灌注水平.     

Estimation of myocardial fibrosis in humans with dual energy CT

BackgroundThe current clinical standard for in vivo imaging of myocardial fibrosis is contrast-enhanced cardiac magnetic resonance (CMR). We sought to validate a novel non-contrast dual energy computed tomography (DECT) method to estimate myocardial fibrosis in patients undergoing CMR with contrast.MethodsAll subjects underwent non-contrast, prospectively-triggered cardiac DECT on a single source scanner with interleaved acquisition between tube voltages of 80 and 140 kVp. Monochromatic images were reconstructed at 11 energies spanning 40–140 keV; a region of interest (ROI) was drawn in the mid-inferoseptal segment, recording mean attenuation value in the ROI, at each energy level. Comparison was made to data from single energy (70 keV) image data. Linear discriminant analysis (LDA) was performed to compare the predictive capability of single vs. multi-energy inferoseptal segment CT attenuation on myocardial fibrosis by both visually assessed LGE (absent/present fibrosis) and CMR T1 mapping-derived myocardial extracellular volume fraction (ECV).ResultsThe multi-energy CT/LDA approach performed better than a single energy approach to discriminate among LGE-CMR classes of present/absence myocardial fibrosis severity, demonstrating correct classification rates of 89% and 71%, respectively. The multi-energy CT/LDA approach also performed better in correctly discriminating normal from elevated ECV, doing so in 89% of patients vs. correct distinction of normal/elevated ECV in only 70% using the single energy approach.ConclusionsNon-contrast cardiac DECT with multi-energy analysis better classifies myocardial fibrosis and extracellular volume compared to what is feasible with non-contrast single energy cardiac CT. These data support further evaluation of this approach to noninvasively assess myocardial fibrosis.     

双源CT双能量心肌血池成像的应用及研究进展

缺血性心脏病已经成为威胁人类健康的高发疾病,判断供血区心肌灌注情况以及冠脉是否有狭窄对预防、治疗缺血性心脏病有重要意义。双能量CT心肌灌注检查在临床上多用于静态评估心肌血池,用于冠心病或心肌梗死的检查。笔者将近年来双源CT双能量心肌血池成像的原理、扫描方法、图像采集及临床应用做一综述。     

正常肝脏、胰腺、脾脏双源CT碘含量测量的初探

目的：使用双源CT双能量扫描,探讨正常肝脏、胰腺、脾脏的碘含量特征,建立正常肝脏、胰腺、脾脏的碘含量参考值。方法：对54例非器质性疾病患者行双源CT双能量双期增强扫描。使用Siemens Dual Energy-Liver VNC 图像处理软件对动脉晚期、门静脉期0．7 mm图像进行分析处理。测量肝脏、胰腺（胰头、胰体、胰尾）、脾脏及腹主动脉（腹腔干开口的上一层面）的含碘值,并计算标化含碘值（nIC ）。结果：正常肝脏在动脉晚期和门脉期的 nIC 值分别为0．10±0．09和0．40±0．09;正常胰腺各部位在动脉晚期的nIC 值分别为0．29±0．32（胰头）、0．29±0．31（胰体）和0．28±0．35（胰尾）,在门脉期分别为0．49±0．21（胰头）、0．46±0．17（胰体）和0．46±0．16（胰尾）;正常脾脏在门脉期的 nIC 值为0．02±0．05。不同年龄、不同性别组间正常肝脏、胰腺和脾脏nIC值的差异均无统计学意义（P＞0．05）;胰腺不同部位nIC值的差异无统计学意义（P＞0．05）;不同扫描期相肝脏nIC值的差异有统计学意义（P＜0．05）。结论：双源CT 扫描可获得正常肝脏、胰腺、脾脏的碘含量,可为肝脏、胰腺及脾脏疾病的诊断提供参考。     

Compound analysis of gallstones using dual energy computed tomography—Results in a phantom model

Purpose

The potential of dual energy computed tomography (DECT) for the analysis of gallstone compounds was investigated. The main goal was to find parameters, that can reliably define high percentage (>70%) cholesterol stones without calcium components.

Materials and methods

35 gallstones were analyzed with DECT using a phantom model. Stone samples were put into specimen containers filled with formalin. Containers were put into a water-filled cylindrical acrylic glass phantom. DECT scans were performed using a tube voltage/current of 140 kV/83 mAs (tube A) and 80 kV/340 mAs (tube B). ROI-measurements to determine CT attenuation of each sector of the stones that had different appearance on the CT images were performed. Finally, semi-quantitative infrared spectroscopy (FTIR) of these sectors was performed for chemical analysis.

Results

ROI-measurements were performed in 45 different sectors in 35 gallstones. Sectors containing >70% of cholesterol and no calcium component (n = 20) on FTIR could be identified with 95% sensitivity and 100% specificity on DECT. These sectors showed typical attenuation of −8 ± 4 HU at 80 kV and +22 ± 3 HU at 140 kV. Even the presence of a small calcium component (<10%) hindered the reliable identification of cholesterol components as such.

Conclusion

Dual energy CT allows for reliable identification of gallstones containing a high percentage of cholesterol and no calcium component in this pre-clinical phantom model. Results from in vivo or anthropomorphic phantom trials will have to confirm these results. This may enable the identification of patients eligible for non-surgical treatment options in the future.     

Non-contrast estimation of diffuse myocardial fibrosis with dual energy CT: A phantom study

BackgroundEstimation of diffuse myocardial fibrosis, substrate for adverse events such as heart failure and arrhythmias in patients with various cardiac disorders, is presently done by histopathology or cardiac magnetic resonance. We sought to develop a non-contrast method to estimate the amount of diffuse myocardial fibrosis leveraging dual energy computed tomography (DECT) in phantoms and a suitable small animal model.Methods and ResultsPhantoms consisted of homogenized bovine myocardium with varying amounts of Type 1 collagen. Fifteen mice underwent sham surgery, no procedure, or transverse aortic constriction (TAC) for 5 or 8 weeks to produce moderate or severe fibrosis, respectively. Phantoms and ex vivo mouse hearts were imaged on a single source, DECT scanner equipped with kVp switching. Monochromatic images were reconstructed at 40–140 keV. Linear discriminant analysis (LDA) was performed on mean myocardial CT numbers derived from single energy (70 keV) images as well as images reconstructed across multiple energies. Classification of myocardial fibrosis severity as low, moderate or severe was more often correct using the multi-energy CT/LDA approach vs. single energy CT/LDA in both phantoms (80.0% vs. 70.0%) and mice (93.3% vs. 33.3%).ConclusionsDECT myocardial imaging with multi-energy analysis better classifies myocardial fibrosis severity compared to a single energy-based approach. Non-contrast DECT can accurately and non-invasively estimate the extent of diffuse myocardial fibrosis in phantom and animal models. These data support further evaluation of this approach for in vivo myocardial fibrosis estimation.     

Radiation dose estimates in dual-source computed tomography coronary angiography

The purpose of this study was to quantify radiation dose parameters of dual-source CT coronary angiography. Eighty patients underwent contrast-enhanced, retrospectively ECG-gated dual-source CT coronary angiography with heart rate-adapted ECG pulsing using two algorithms: In 40 patients, the tube current was reduced to 20% (A_min1) of the normal tube current (A_max) outside the pulsing window; in 40 patients tube current was reduced to 4% (A_min2) of A_max. Mean CTDI_vol in the A_min1 group was 45.1 ± 3.6 mGy; the mean CTDI_vol in the A_min2 group was 39.1 ± 3.2 mGy, with CTDI_vol in the A_min2 group being significantly reduced when compared to the A_min1 group (P < 0.001). A significant negative correlation was found between CTDI_vol and heart rate in group A_min1 (r = −0.82, P < 0.001), whereas no correlation was found between CTDI_vol and heart rate in group A_min2 (r = −0.066). Using the conversion coefficient for the chest, dual-source CT coronary angiography resulted in an estimated mean effective dose of 8.8 mSv in the A_min1 group and 7.8 mSv in the A_min2. Radiation exposure of dual-source CT coronary angiography using an ECG-pulsing protocol reducing the tube current to 20% significantly decreases with increasing heart rates, despite using wider pulsing windows at higher heart rates. When using a protocol with reduced tube current of 4%, the radiation dose is significantly lower, irrespective of the heart rate.     

Diagnostic accuracy of cardiac computed tomography angiography for myocardial infarction

AIM:To investigate diagnostic accuracy of high,low and mixed voltage dual energy computed tomography(DECT) for detection of prior myocardial infarction(MI).METHODS:Twenty-four consecutive patients(88% male,mean age 65 ± 11 years old) with clinically documented prior MI(> 6 mo) were prospectively recruited to undergo late phase DECT for characterization of their MI.Computed tomography(CT) examinations were performed using a dual source CT system(64-slice Definition or 128-slice Definition FLASH,Siemens Healthcare) with initial first pass and 10 min late phase image acquisitions.Using the 17-segment model,regional systolic function was analyzed using first pass CT as normal or abnormal(hypokinetic,akinetic,dyskinetic).Regions with abnormal systolic function were identified as infarct segments.Late phase DE scans were reconstructed into:140 kVp,100 kVp,mixed(120 kVp) images and iodine-only datasets.Using the same 17-segment model,each dataset was evaluated for possible(grade 2) or definite(grade 3) late phase myocardial enhancement abnormalities.Logistic regression for correlated data was used to compare reconstructions in terms of the accuracy for detecting infarct segments using late myocardial hyperenhancement scores.RESULTS:All patients reported prior history of documented myocardial infarction,with most occurring more than 5 years prior(n = 18;75% of cohort).Fiftyfive of 408(13%) segments demonstrated abnormal wall motion and were classified as infarct.The remaining 353 segments were classified as non-infarcted segments.A total of 1692 segments were analyzed for late phase enhancement abnormalities,with 91(5.5%) segments not interpretable due to artifact.Combined grades 2 and 3 compared to grade 3 only enhancement abnormalities demonstrated significantly higher sensitivity and similar specificity for detection of infarct segments for all reconstructions evaluated.Evaluation of different voltage acquisitions demonstrated the highest diagnostic performance for the 100 kVp reconstruction which had higher diagnostic accuracy(87%;95%CI:80%-90%),sensitivity(86%-93%;95%CI:54%-78%) and specificity(90%;95%CI:86%-93%) compared to the other reconstructions.For sensitivity,there were significant differences noted between 100 kVp vs 140 kVp(P<0.0005),100 kVp vs mixed(P<0.0001),and 100 kVp vs iodine only(P<0.005) using combined grade 2 and grade 3 perfusion abnormalities.For specificity,there were significant differences noted between 100 kVp vs 140 kVp(P<0.005),and 100 kVp vs mixed(P<0.01) using combined grades 2 and 3 perfusion abnormalities.CONCLUSION:Low voltage acquisition CT,100 kVp in this study,demonstrates superior diagnostic performance when compared to higher and mixed voltage acquisitions for detection of prior MI.     

Detection of local recurrent disease in musculoskeletal tumors: magnetic resonance imaging versus computed tomography

A 2 1/2-year prospective study of surgically treated malignant mesenchymal neoplasms showed magnetic resonance imaging (MRI) to be superior to computed tomography (CT) in sensitivity for local recurrent disease measuring less than 15 cm³. Larger masses were detected with similar sensitivity; specificity and predictive values did not differ. The presence of areas of high signal intensity on T2-weighted images proved to be a reliable criterion except in fibrous neoplasms. However, differentiation between non-hemorrhagic fluid collections, cross-sectioned veins or bowel contents and small tumor nodules cannot be made simply by signal intensity, but has to be based upon the evaluation of gross morphologic criteria.     

双源CT双能量头颅脑血管造影在颅内动脉瘤诊断中的临床应用

目的：探讨双源CT双能量颅脑血管造影（DE-CTA）在颅内动脉瘤诊断中的临床价值。方法回顾性分析2011年6月至2013年12月我院收治的84例有完整临床资料的脑动脉瘤患者。所有患者术前均行DE-CTA检查诊断脑动脉瘤,其中,19例DE-CTA诊断后经开颅手术夹闭治疗,65例经DSA介入栓塞治疗。所有患者均有治疗后复查DE-CTA资料。 DE-CTA处理完成后,由2位资深放射医师评价图像质量及进行诊断,统计并比较DE-CTA检查与手术及数字减影血管造影（DSA）检查结果。结果84例动脉瘤患者均行DE-CTA检查,共检出动脉瘤99个。19例患者行DE-CTA检查诊断后经开颅手术夹闭治疗证实,均为单发较大动脉瘤破裂出血,手术所见与DE-CTA检查结果相符;65例患者经DSA介入栓塞治疗。 DE-CTA检查结果与手术及DSA所见相近。结论 DE-CTA作为一种快捷、简便、无创而又能准确诊断脑动脉瘤的技术,在临床诊断脑动脉瘤中具有较高的应用价值。     

双源CT双能量成像在脑血管检查中的应用价值

目的：探讨双源CT双能量成像在脑血管检查中的应用价值。方法：60例患者随机等分成两组：A组30例,使用一代双源CT检查,扫描参数140／80kVp,55／243mAs;B组30例,使用二代双源CT检查,扫描参数80／Sn 140kVp．208／104mAs。比较两组图像的颈动脉血管平均CT值、图像噪声、血管信噪比、对比噪声比以及图像质量主观评分;同时比较两组检查的CT容积剂量指数（CTDIv01）、剂量长度乘积（DLP）和有效剂量（ED）。统计方法采用成组资料两样本r检验。结果：两组间影像质量的主观评估与客观评估各指标的差异均无统计学意义（P〉0．05）。两组间辐射剂量差异有统计学意义（P〈0．05）,B组有效剂量为（0．27±0．01）mSv,较A组的（0．37±0．02）mSv降低约30％。结论：相较于一代双源CT,二代双源CT脑血管双能量成像能获得良好的图像质量,同时辐射剂量明显降低。     

Usefulness of cone beam computed tomography in temporomandibular joints with soft tissue pathology

Objective

The aim of the study was to evaluate the usefulness of cone beam CT (CBCT) in temporomandibular joints (TMJs) with soft tissue pathology.

Methods

106 TMJs of 55 patients with temporomandibular disorder (TMD) were examined by MRI and CBCT. MR images were used for the evaluation of disc displacement, disc deformity, joint effusion and obscurity of temporal posterior attachment (TPA). CBCT images were evaluated for the presence or absence of osseous abnormalities. The χ² test was used to analyse the association between MRI and CBCT findings.

Results

MRI of 106 TMJs revealed disc displacement, disc deformity, joint effusion and obscurity of the TPA in 68, 73, 28 and 27 joints, respectively. Of the 68 TMJs with disc displacement, anterior disc displacement without reduction (ADDWR) was seen most frequently (47/68). CBCT imaging found 65 TMJs were characterized by the presence of osseous abnormalities and were significantly associated with disc deformity and ADDWR (P < 0.05). There was no statistically significant association between the presence of joint effusion and obscurity of TPA and TMJ osseous abnormalities.

Conclusions

TMD patients with confirmed ADDWR or disc deformity on MRI are at risk of having osseous abnormalities in the TMJ and further examination with CBCT is recommended.     

Dual energy computed tomography of lung nodules: differentiation of iodine and calcium in artificial pulmonary nodules in vitro

Background

Iodine enhancement is a marker for malignancy in pulmonary nodules. The purpose of this in vitro study was to assess whether dual energy computed tomography (DECT) can be used to detect iodine and to distinguish iodine from disperse calcifications in artificial pulmonary nodules.

Materials and methods

Small, medium, and large artificial nodules (n = 54), with increasing concentrations of iodine or calcium corresponding to an increase in Hounsfield Units (HU) of 15, 30, 45, and 90 at 120 kV, were scanned in a chest phantom with DECT at 80 and 140 kV. Attenuation values of each nodule were measured using semi-automated volumetric analysis. The mean DE ratio with 95% confidence intervals (CI) was calculated for each nodule.

Results

The mean maximum diameter of the 18 small nodules was 12 mm (standard deviation: 0.4), 16 mm (0.4) for the 18 medium nodules, and 30 mm (1.1) for the 18 large nodules. There was no overlap of 95% CI of DE ratios of iodine and calcium in nodules ≥16 mm. In nodules <16 mm, there was an overlap of DE ratios in low contrast lesions.

Conclusion

DECT can distinguish iodine from calcium in artificial nodules ≥16 mm in vitro. In smaller lesions, a clear differentiation is not possible.