双能CT灌注与CTA诊断慢性血栓性肺动脉高压:与核素闪烁扫描诊断准确性及一致性的对照研究

正目的探讨双能CT(DECT)灌注联合CT血管成像(CTA)与核素闪烁扫描的肺通气/血流灌注比值(V/Q)诊断慢性血栓性肺动脉高压(CTEPH)的准确性,并比较DECT与核     

双能CT在克罗恩病中的研究进展

克罗恩病（CD）是一种慢性、反复发作的炎症性肠病,需要长期监测药物治疗反应。双能CT(DECT)不仅能提供形态学特征,还可生成常规CT影像、虚拟单能谱影像、碘密度图等不同的能谱影像来提供定量特征,实现无创、准确监测。DECT已逐渐应用于CD的诊断与鉴别诊断、活动性及严重程度评估、疗效评估与预后预测等方面。就DECT在CD中的应用进展予以综述。     

妊娠会影响CT肺血管成像检查的血管增强吗？

目的是评价妊娠在CT肺血管成像（CTPA）检查中是否会影响肺动脉的对比增强。本研究回顾性分析了同一时期怀疑急性肺栓塞的16例妊娠病人及16名非妊娠妇女的CTPA检查．通过测量肺动脉的CT值来评价肺部血管的强化。本研究采用盲法评估,对肺动脉对比增强做了主观分级。结果2组的动脉增强的差异有统计学意义。     

DECT虚拟去骨图CT值测量对脊柱急性骨髓损伤的诊断价值

目的 探讨双能CT(DECT)虚拟去骨(VNC)图中CT值测量在脊柱急性骨髓损伤中的诊断价值.方法 对急性胸腰椎外伤的患者分别行MR及DECT成像,以MRI作为参考标准,DECT数据经双能去骨后处理得到显示骨髓信息的VNC图,分别测量VNC图中骨髓正常区域和损伤区域的CT值,采用单因素方差分析法进行统计分析,比较骨髓正常区域与骨髓损伤区域的CT值是否存在差异,并与MR进行对照.结果 DECT虚拟去骨图中,急性骨髓损伤区域的CT值比骨髓正常区域的CT值明显升高,且差异具有统计学意义(P＜0.05),与DECT伪彩图和MRI具有较高的一致性.腰椎骨髓损伤区域与胸椎骨髓损伤区域的CT值差别无统计学意义(P＞0.05).结论 结合DECT伪彩图,DECT VNC图中骨髓CT值的测量对急性骨髓损伤的诊断具有一定定性诊断价值.     

双能量非线性融合技术补救非峰值肺动脉CTA图像质量的应用价值

【摘要】目的：探讨双能量非线性融合（NLB）技术在补救非峰值肺动脉CTA图像质量（主观评分≤3分）中的应用价值。方法：回顾性搜集64例图像质量主观评分≤3分的肺动脉双能CTA图像（线性融合图像,LB组）,将每例患者的原始图像采用NLB技术进行后处理,获得非线性融合图像（NLB组）。比较两组图像上7支肺血管（肺动脉主干、右肺动脉、左肺动脉、左肺上叶动脉、左肺下叶动脉、右肺上叶动脉、右肺下叶动脉）、栓子及背部肌肉的CT值及其标准差（SD）、信号噪声比（SNR）、对比噪声比（CNR）和图像质量主观评分。主观评分采用5分法,≤3分为非峰值图像。结果：CT显示肺动脉栓塞31例。NLB组7支肺血管CT值、SNR及CNR较LB组提高（P＜0.05）。栓子平均CT值NLB组低于LB组,NLB组栓子CNR较LB组升高（P<0.05）,而NLB组血管层面背部肌肉平均CT值和SD与LB组相比,差异无统计学意义（P>0.05）。NLB组主观评分高于LB组,主观评分提高0.53分（P＜0.05）。结论：NLB技术可提高图像质量并增强肺栓子与血管对比度,补救非峰值肺动脉CTA图像。     

急性肺栓塞的影像检查技术应用进展

急性肺栓塞(APE)是一类以骤然起病、进展迅速且死亡率高为特征的临床病理生理综合征。早期定性诊断和预后评估对于改善APE流行病学现状尤为重要。CT肺动脉血管成像、肺通气灌注显像、MR肺血管成像以及超声成像等影像检查方法在APE早期诊断、危险分层和预后评估中发挥着重要作用。就上述各种影像检查方法在APE定性检测及定量评估中的应用进展及限度进行综述。     

双能CT成像在直肠癌术前分期评估中的应用进展

双能CT成像(DECT)利用单能量成像、物质分离成像和能谱曲线等对直肠癌肿瘤病灶、肠周脂肪组织及肠周淋巴结的碘基质及能谱曲线特征进行定性定量分析,更加精确地鉴别肠周脂肪受侵与否以及转移性与非转移性淋巴结。可以与常规影像检查方法互补进一步提高直肠癌术前分期的准确性。就DECT成像的原理及其在评估直肠癌术前分期方面的应用进展进行综述。     

128层高螺距双源CT、双能量CT、常规螺旋CT扫描对肺血管成像影像质量和放射剂量影响的对比研究

目的为了比较128层高螺距双源CT(DSCT)、双能量CT(DECT)和传统单源螺旋CT(SCT)对肺血管成像(CTA)影像质量和辐射剂量的影响。方法按照5种不同方案进行肺动脉CTA检查:高螺距DSCT(100kV),高螺距DSCT     

多层螺旋CT血管成像在肺动脉疾病中的临床应用

目的评价多层螺旋CT血管成像对探测肺动脉疾病的临床应用价值。方法 60例经临床或病理证实的肺动脉疾病患者均经MSCT肺动脉成像检查,对所有患者的影像表现进行回顾性分析。结果本组60例患者肺动脉CTA的图像质量完全满足诊断需要。研究证实,60例中38例为肺动脉栓塞,6例中央型肺癌侵犯肺血管,3例为肺动静脉瘘,5例为肺动脉高压,8例肺动脉成像未见异常。结论 MSCT的三维肺血管图像可立体、直观地显示肺血管的解剖结构及其与周围组织的空间关系,能及时发现和诊断肺动脉疾病,指导肺栓塞的治疗及评价疗效,也可为中央型肺癌制定手术方案提供准确的影像学信息。     

肺动脉的MR检查

ＭＲ作为一种安全无创性检查肺动脉的方法,作用日益受到重视。常规的自旋回波技术(ＳＥ)、梯度回波技术(ＧＲＥ)、相位对比技术(ＰＣ)已经普遍应用[1,2],而增强ＭＲ肺动脉造影,尤其是三维对比增强ＭＲ肺动脉造影,以及ＭＲ肺灌注成像等新型技术也越来越引起人们的重视。一、增强ＭＲ肺动脉造影(ＣＥＭＲＰＡ)传统ＭＲ血管造影主要是基于时间飞跃(ｔｉｍｅｏｆｆｌｉｇｈｔ,ＴＯＦ)效应,但它在肺部的应用却受限,主要因为受心脏和呼吸的运动、肺部血管复杂的解剖结构、肺部复杂的血流模式以及空气/组织界面间巨大磁化率伪影等多因素的影响[3]。…     

Dual energy CT for the assessment of lung perfusion--correlation to scintigraphy

Purpose of this study was to determine the diagnostic value of dual energy CT in the assessment of pulmonary perfusion with reference to pulmonary perfusion scintigraphy. Thirteen patients received both dual energy CT (DECT) angiography (Somatom Definition, Siemens) and ventilation/perfusion scintigraphy. Median time between scans was 3 days (range, 0-90). DECT perfusion maps were generated based on the spectral properties of iodine. Two blinded observes assessed DECT angiograms, perfusion maps and scintigrams for presence and location of perfusion defects. The results were compared by patient and by segment, and diagnostic accuracy of DECT perfusion imaging was calculated regarding scintigraphy as standard of reference. Diagnostic accuracy per patient showed 75% sensitivity, 80% specificity and a negative predictive value of 66%. Sensitivity per segment amounted to 83% with 99% specificity, with 93% negative predictive value. Peripheral parts of the lungs were not completely covered by the 80 kVp detector in 85% of patients. CTA identified corresponding emboli in 66% of patients with concordant perfusion defects in DECT and scintigraphy. Dual energy CT perfusion imaging is able to display pulmonary perfusion defects with good agreement to scintigraphic findings. DECT can provide a pulmonary CT angiogram, high-resolution morphology of the lung parenchyma and perfusion information in one single exam.     

Lung perfusion analysis with dual energy CT in patients with suspected pulmonary embolism--influence of window settings on the diagnosis of underlying pathologies of perfusion defects

Purpose

On lung perfusion analysis with dual energy CT (DECT) in patients with suspected pulmonary embolism (PE) commonly three patterns of perfusion defects (PD) are observed: wedge-shaped, circumscribed but not wedge-shaped, and patchy. We investigated the influence of different window settings on the identification of the underlying pathologies for these types of PD.

Materials and methods

3724 segments in 196 consecutive patients who underwent pulmonary DECT angiography for clinically suspected acute PE were analyzed. Iodine distribution in the lung parenchyma was calculated from the dual energy data and displayed as color map in axial, sagittal and coronal view. Afterwards, lung and angiography window were applied separately and assessed for pulmonary embolism and pathologies of the lung parenchyma.

Results

1420 segments in 141 patients showed PD, of which 276 were wedge-shaped, 287 circumscribed and 857 patchy. Circumscribed PD were associated in 99% with interstitial or alveolar fluid collections and in 1% with located bullae. Patchy PD were associated in 65% with emphysematous or fibrotic changes, in 38% with diffuse infiltrations or interstitial fluid collections and in 0.2% with PE. The underlying pathologies for wedge-shaped PD were in 78% PE, in 3% tumors compressing pulmonary arteries, in another 3% located bullae and in further 3% infiltrations. 13% (n = 15) of the segments in this group did not show vascular or parenchymal pathologies, but in 80% (n = 10) of these cases patients had PE in another segment. Totally n = 6 of wedge-shaped PD in 5 patients remained with unclear direct cause.

Conclusion

Whereas patchy and circumscribed PD are almost exclusively associated with pathologies of the lung parenchyma, wedge-shaped PD are mostly associated with PE. For a small number of wedge-shaped PD the underlying cause cannot be detected with DECT. Very small peripherally situated micro-emboli may be discussed as a reason. However, prospective trials are needed to clarify the value of this finding.     

Dual-energy CT based vascular iodine analysis improves sensitivity for peripheral pulmonary artery thrombus detection: An experimental study in canines

Purpose

To evaluate the performance of dual-energy CT (DECT) based vascular iodine analysis for the detection of acute peripheral pulmonary thrombus (PE) in a canine model with histopathological findings as the reference standard.

Materials and methods

The study protocol was approved by our institutional animal committee. Thrombi (n = 12) or saline (n = 4) were intravenously injected via right femoral vein in sixteen dogs, respectively. CT pulmonary angiography (CTPA) in DECT mode was performed and conventional CTPA images and DECT based vascular iodine studies using Lung Vessels application were reconstructed. Two radiologists visually evaluated the number and location of PEs using conventional CTPA and DECT series on a per-animal and a per-clot basis. Detailed histopathological examination of lung specimens and catheter angiography served as reference standard. Sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) of DECT and CTPA were calculated on a segmental and subsegmental or more distal pulmonary artery basis. Weighted κ values were computed to evaluate inter-modality and inter-reader agreement.

Results

Thirteen dogs were enrolled for final image analysis (experimental group = 9, control group = 4). Histopathological results revealed 237 emboli in 45 lung lobes in 9 experimental dogs, 11 emboli in segmental pulmonary arteries, 49 in subsegmental pulmonary arteries, 177 in fifth-order or more distal pulmonary arteries. Overall sensitivity, specificity, accuracy, PPV, and NPV for CTPA plus DECT were 93.1%, 76.9%, 87.8%, 89.4%, and 84.2% for the detection of pulmonary emboli. With CTPA versus DECT, sensitivities, specificities, accuracies, PPVs, and NPVs are all 100% for the detection of pulmonary emboli on a segmental pulmonary artery basis, 88.9%, 100%, 96.0%, 100%, and 94.1% for CTPA and 90.4%, 93.0%, 92.0%, 88.7%, and 94.1% for DECT on a subsegmental pulmonary artery basis; 23.8%, 96.4%, 50.4%, 93.5%, and 36.7% for CTPA and 95.9%, 75.5%, 88.2%, 86.5%, and 91.9% on a sub-subsegmental and more distal pulmonary artery basis, respectively. Good inter-modality (κ = 0.65, P < 0.001) and inter-reader (κ = 0.70, P < 0.001) agreement were observed.

Conclusion

With histopathological findings as the reference standard, DECT based vascular iodine analysis improves the sensitivity for detecting peripheral PE compared with CTPA, albeit at the price of decreased specificity and PPV.     

Imaging of acute pulmonary embolism using a dual energy CT system with rapid kVp switching: Initial results

Purpose

Computed tomography pulmonary angiography (CTPA) is considered as clinical gold standard for diagnosing pulmonary embolism (PE). Whereas conventional CTPA only offers anatomic information, dual energy CT (DECT) provides functional information on blood volume as surrogate of perfusion by assessing the pulmonary iodine distribution. The purpose of this study was to evaluate the feasibility of lung perfusion imaging using a single-tube DECT scanner with rapid kVp switching.

Materials and methods

Fourteen patients with suspicion of acute PE underwent DECT. Two experienced radiologists assessed the CTPA images and lung perfusion maps regarding the presence of PE. The image quality was rated using a semi-quantitative 5-point scale: 1 (=excellent) to 5 (=non-diagnostic). Iodine concentrations were quantified by a ROI analysis.

Results

Seventy perfusion defects were identified in 266 lung segments: 13 (19%) were rated as consistent with PE. Five patients had signs of PE at CTPA. All patients with occlusive clots were correctly identified by DECT perfusion maps. On a per patient basis the sensitivity and specificity were 80.0% and 88.9%, respectively, while on a per segment basis it was 40.0% and 97.6%, respectively. None of the patients with a homogeneous perfusion map had an abnormal CTPA. The overall image quality of the perfusion maps was rated with a mean score of 2.6 ± 0.6. There was a significant ventrodorsal gradient of the median iodine concentrations (1.1 mg/cm³ vs. 1.7 mg/cm³).

Conclusion

Lung perfusion imaging on a DE CT-system with fast kVp-switching is feasible. DECT might be a helpful adjunct to assess the clinical severity of PE.     

Dual energy CT: preliminary observations and potential clinical applications in the abdomen

Dual energy CT (DECT) is a new technique that allows differentiation of materials and tissues based on CT density values derived from two synchronous CT acquisitions at different tube potentials. With the introduction of a new dual source CT system, this technique can now be used routinely in abdominal imaging. Potential clinical applications include evaluation of renal masses, liver lesions, urinary calculi, small bowel, pancreas, and adrenal glands. In CT angiography of abdominal aortic aneurysms, dual energy CT techniques can be used to remove bones from the datasets, and virtual unenhanced images allow differentiation of contrast agent from calcifying thrombus in patients with endovascular stents. This review describes potential applications, practical guidelines, and limitations of dual energy CT in the abdomen.     

Persistent respiratory failure after SARS-CoV-2 infection: The role of dual energy computed tomography. A case report

Background: COVID-19 disease is often complicated by respiratory failure, developing through multiple pathophysiological mechanisms, with pulmonary embolism (PE) and microvascular thrombosis as key and frequent components. Newer imaging modalities such as dual-energy computed tomography (DECT) can represent a turning point in the diagnosis and follow-up of suspected PE during COVID-19. Case presentation: A 78-year-old female presented to our internal medicine 3 weeks after initial hospitalization for COVID-19 disease, for recrudescent respiratory failure needing oxygen therapy. A computed tomography (CT) lungs scan showed a typical SARSCoV-2 pneumonia. Over the following 15 days, respiratory function gradually improved. Unexpectedly, after 21 days from symptom onset, the patient started complaining of breath shortening with remarkable desaturation requiring high-flow oxygen ventilation. CT pulmonary angiography and transthoracic echocardiography were negative for signs of PE. Thereby, Dual-energy CT angiography of the lungs (DECT) was performed and detected diffuse peripheral microembolism. After 2 weeks, a second DECT was performed, showing a good response to the anticoagulation regimen, with reduced extent of microembolism and some of the remaining emboli partially recanalized. Discussion: DECT is an emerging diagnostic technique providing both functional and anatomical information. DECT has been reported to produce a much sharper delineation of perfusion defects than pulmonary scintigraphy, using a significantly lower equivalent dose of mSv. We highlight that DECT is particularly useful in SARS-Cov-2 infection, in order to determine the predominant underlying pathophysiology, particularly when respiratory failure prolongs despite improved lung parenchymal radiological findings     

Dual Energy CT lung perfusion imaging--correlation with SPECT/CT

Objective

Aims were (1) to determine the diagnostic accuracy of Dual Energy CT (DECT) in the detection of perfusion defects and (2) to evaluate the potential of DECT to improve the sensitivity for PE.

Methods

15 patients underwent Dual Energy pulmonary CT angiography (DE CTPA) and a combination of lung perfusion SPECT/CT and ventilation scintigraphy. CTPA and DE iodine distribution maps as well as perfusion SPECT/CT and inhalation scintigrams were reviewed for pulmonary embolism (PE) diagnosis. DECT and SPECT perfusion images were assessed regarding localization and extent of perfusion defects. Diagnostic accuracy of DE iodine (perfusion) maps was determined with reference to SPECT/CT. Diagnostic accuracies for PE detection of DECT and of SPECT/CT with ventilation scintigraphy were calculated with reference to the consensus reading of all modalities.

Results

DE CTPA had a sensitivity/specificity of 100%/100% for acute PE, while the combination of SPECT/CT and ventilation scintigraphy had a sensitivity/specificity of 85.7%/87.5%. For perfusion defects, DECT iodine maps had a sensitivity/specificity of 76.7% and 98.2%.

Conclusion

DECT is able to identify pulmonary perfusion defects with good accuracy. This technique may potentially enhance the diagnostic accuracy in the assessment of PE.     

Triphasic contrast injection improves evaluation of dual energy lung perfusion in pulmonary CT angiography

Purpose

Lung perfusion analysis at dual energy CT (DECT) is sensitive to beam hardening artifacts from dense contrast material (CM). We compared two scan and four CM injection protocols in terms of severity of artifacts and attenuation levels in the thoracic vessels.

Methods and materials

Data of 120 patients who had undergone dual source dual energy CT pulmonary angiography for suspected acute pulmonary embolism were evaluated. Group 1 (n = 30) was scanned in craniocaudal direction using 64 × 0.6 mm collimation; groups 2–4 (n = 30 each) were scanned in caudocranial direction using 14 × 1.2 mm collimation. In groups 1–3 biphasic injection protocols with different amounts of CM and NaCl were investigated. In group 4 a split-bolus protocol with an initial CM bolus of 50 ml followed by 30 ml of a 70%:30% NaCl/CM mixture and a 50 ml NaCl chaser bolus was used. CT density values in the subclavian vein (SV), superior vena cava (SVC), pulmonary artery tree (PA), and the descending aorta (DA) were measured. Artifacts arising from the SV and SVC on DE pulmonary iodine distribution map were rated on a scale from 1 to 5 (1 = fully diagnostic; 5 = non-diagnostic) by two blinded readers.

Results

In protocol 4 mean attenuation in the SV (645 ± 158 HU) and SVC (389 ± 114 HU) were significantly lower compared to groups 1–3 (p < 0.002). Artifacts in group 4 (1.1 ± 0.4 and 1.5 ± 0.7 for the SV and SVC, respectively) were rated significantly less severe compared to group 1 (3.2 ± 1.0 and 3.0 ± 1.1), 2 (2.6 ± 1.1 and 2.3 ± 1.0) and 3 (1.9 ± 0.9 and 1.9 ± 0.7) (p < 0.01 for all), whereas no significant difference was found between groups 1 and 2 for the subclavian vein (p = 0.07). Attenuation in the PA was also significantly lower in group 4 (282 ± 116 HU) compared to group 1 (397 ± 137 HU), group 2 (376 ± 115 HU) and group 3 (311 ± 104 HU), but still on a diagnostic level.

Conclusion

Split-bolus injection provides sufficient attenuation for pulmonary DECT angiography while beam hardening artifacts arising from high density contrast material in the thoracic vessels can be reduced significantly.     

Dual-energy MDCT: Comparison of pulmonary artery enhancement on dedicated CT pulmonary angiography, routine and low contrast volume studies

Purpose

The aim of this study was (a) to compare arterial enhancement in simultaneously acquired high- and low-kilovoltage images; and (b) to determine whether low tube-voltage imaging would permit PE evaluation on routine chest CT studies or CTPA studies performed with a low volume of contrast media.

Materials and methods

We compared 20 CTPA studies (CTPA group), 20 routine thoracic CT studies (RT group) and 10 CTPA studies performed with reduced volume of contrast media (RC group). HU values were measured in all groups at 80 kVp and 140 kVp images in multiple pulmonary arterial segments bilaterally. The diagnostic quality of the central and peripheral vascular enhancement and the image noise were evaluated at both energies using a five-point scale.

Results

For all patients, the mean CT attenuation values were greater at 80 kVp than 140 kVp images (p < 0.001). At 80 kVp, CTPA group attenuation values were greater than RT group (p = 0.03) with a similar trend at 140 kVp (p = 0.08). At both 140 kVp and 80 kVp, CTPA group attenuation values were greater than RC group (p = 0.02 and p = 0.03, respectively). Qualitative analysis showed that at 140 kVp CTPA studies had better global image quality scores than RT (p = 0.003) and RC (p = 0.001) groups. However, at 80 kVp, there was no significant difference of global image quality between CTPA and the other groups (p = 0.4 and p = 0.5, respectively). Although measurable image noise was greater at 80 kVp than 140 kVp (p < 0.001), qualitative analysis revealed lower image noise at 80 kVp images.

Conclusion

DECT at 80 kVp increases arterial enhancement in both CTPA and routine studies. For routine studies this results in central and peripheral enhancement quality equivalent to that of CTPA studies. Low tube-voltage imaging allows marked contrast volume reduction for CTPA. In selected cases, satisfactory lower radiation dose CT might be achievable using lower kVp imaging alone.     

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.