Defectos de perfusión en el mapa de iodo pulmonar: causas y semiología

Objective

to describe the usefulness of dual-energy CT for obtaining pulmonary perfusion maps to provide morphological and functional information in patients with pulmonary embolisms. To review the semiology of perfusion defects due to pulmonary embolism so they can be differentiated from perfusion defects due to other causes: alterations outside the range used in the iodine map caused by other diseases of the lung parenchyma or artifacts.

CT能谱成像定量碘基物质图对肺栓塞的诊断价值

目的 评价CT能谱成像定量碘基物质图对肺栓塞(PE)的诊断价值.方法 53例怀疑PE的患者行CT常规平扫及能谱增强扫描,并进行数据后处理,同时获得单能量肺CTA及碘基物质图像.观察肺动脉内有无栓子,记录栓子的位置、数目及栓塞程度;分析碘基物质图表现,记录肺内灌注异常的位置及数目,测量碘含量.计数资料比较采用x2检验,不同碘含量比较分别采用两样本的秩和检验及符号秩和检验.结果 33例患者的碘基物质图密度均匀,CTA未显示PE;19例患者共显示93个栓子,其中肺叶26个,肺段54个,亚段13个.51个栓子为闭塞性,42个栓子为非闭塞性.所有闭塞性栓塞均有灌注减低表现,非闭塞性栓塞中11个显示灌注降低.CTA栓子的栓塞程度与肺内有无灌注减低区差异有统计学意义(x2=39.94,P＜0.01).正常肺实质区[(1.92±0.54)g/L]与灌注减低区[(0.30±0.20)g/L]碘基物质含量差异有统计学意义(Z=-5.63,P＜0.01).PE低灌注区抗凝治疗前[(0.26±0.23)g/L]与治疗后[(0.94±0.50)g/L]的碘基物质含量差异有统计学意义(Z=-3.93,P＜0.01).结论 CT能谱成像可以为PE提供定性、定量分析,可以作为评价病变程度以及指导治疗的有效手段.     

Fire victim identification by post-mortem dental CT: Radiologic evaluation of restorative materials after exposure to high temperatures

Objectives

The aim of this study was to evaluate the use of high resolution CT to radiologically define teeth filling material properties in terms of Hounsfield units after high temperature exposure.

Methods

122 human molars with 10 different filling materials at defined filling diameters were examined. The teeth were CT scanned both before and after the exposure to different temperatures. After image reconstruction, the teeth and filling materials were analyzed regarding their morphology and Hounsfield units (HU) using an extended HU scale.

Results

The majority of filling materials diminished in size at temperatures ≥400 °C. HU values were stable for all materials up till 200 °C, and only slightly changed up to 600 °C. Cerec, Dyract and dentin showed only minor changes in HU at all temperatures. The other materials, inclusive enamel, showed specific patterns, either increasing or decreasing in HU with increasing temperatures over 600 °C.

Conclusions

Over 600 °C the filling materials show specific patterns that can be used to discriminate filling materials. Ultra high resolution CT may improve the identification processes in fire victims. Existing 3D visualization presets for the dentition can be used until 600 °C and have to be optimized for bodies exposed to higher temperatures.     

双源CT双能量肺灌注成像对肺栓塞的初步研究

目的 探讨双源CT双能量扫描肺灌注成像的临床诊断价值.方法 选择临床怀疑肺动脉栓塞30例患者行双源CT双能量扫描,生成140、80 kV和融合系数为0.3的3组数据.根据融合数据的CT肺动脉造影(CTPA)图像将患者分为肺栓塞组和正常组.采用双能量评估软件将薄层重建数据进行灌注成像分析,将双肺野分为上、中、下3部分,正常组受试者肺组织灌注定量的双侧比较行配对t检验,2组间肺组织灌注量比较行独立样本t检验,并对融合图像行MinIP,评估肺组织通气情况.结果 正常组(16例)肺灌注均匀,无明显灌注缺损及减弱,灌注定量分析显示左、右全肺的灌注量分别为(27±7)、(28±8)HU,两侧比较差异无统计学意义(t=-1.73,P＞0.05);左肺上、中、下部的灌注量分别为(23±6)、(24±6)、(28±8)HU,右肺上、中、下部灌注量分别为(26±8)、(27±8)、(28±9)HU,两侧分别比较差异均无统计学意义(t值分别为-1.91、-1.96、-1.73,P值均＞0.05).肺栓塞组(14例)CTPA图像显示肺动脉干、段及亚段充盈缺损,肺灌注成像表现为栓塞血管所支配肺野区域的灌注缺损或缺失,灌注定量分析显示全肺及中、下肺的灌注量分别为(22±5)、(22±8)、(21±8)HU,与正常组分别比较差异均有统计学意义(t值分别为-2.10、-2.32、-2.63,P值均＜0.05＝.MinIP显示通气异常区与灌注异常区具有良好的一致性.结论 双源CT双能量扫描可用于肺栓塞的诊断,有利于肺栓塞的早期发现和精确解剖定位.

Abstract：

Objective To explore the diagnostic values of dual energy lung perfusion in the diagnosis of pulmonary embolism by using dual-source CT (DSCT). Methods Thirty patients with clinically suspected pulmonary embolism underwent dual-energy scanning with dual-source CT. The scanned data were integrated into three groups including 140, 80 kV and coefficient of 0.3. According to the CT pulmonary angiography (CTPA) of the fusion data, the patients were divided into pulmonary embolism group and normal group. The thin-slice reconstruction of data was analyzed using dual-energy perfusion imaging analysis software. The lung field was divided into upper, middle and lower part to make quantitative analysis of lung tissue perfusion. Paired t-tests were used in the normal patients to compare bilateral lungs, and independent samples t-tests were applied to compare the embolism group and normal group, while minimum intensity projection images (MinIP) were utilized in the assessment of lung ventilation. Results Dual energy CT showed symmetrical homogeneous perfusion in 16 normal cases, without significant perfusion defects. Quantitative analysis showed that left and right lung perfusion were (27 ± 7) and (28 ± 8 ) HU respectively, and no significant difference was found between the two sides ( t=-1.73, P ＞0.05 ).Perfusion of the left upper, middle and lower lung was ( 23 ± 6), (24 ± 6), and (28 ± 8) HU respectively, while the perfusion of right upper, middle and lower lung was (26 ±8), (27 ±8), and (28 ±9) HU respectively, showing no statistical significant difference between the two sides (t=-1.91, -1.96,-1.73 ,P＞0.05 ). Angiography of pulmonary embolism group(14 cases)showed filling defects in the pulmonary trunk, segments and sub-segments. Pulmonary perfusion imaging showed low perfusion or defectsin lung field that dominated by embolic vessels. Quantitative analysis showed that the perfusion of the whole lung and the middle and lower lung were (22 ±5), (22 ±8), and (21 ±8) HU in the embolism group,which were significantly different from the normal group (t=-2. 10, -2.32, -2.63, P＜0.05).Minimum intensity projection images showed a good consistency of abnormal ventilation zone area and perfusion abnormalities. Conclusions Pulmonary perfusion status, especially pulmonary embolism, can be analyzed by dual energy CT scanning. It helps to early discover and precisely locate the embolism.     

Paediatric radiology and scientific contributions to radiation dose at the meeting of the German Radiological Society—An analysis of an 11-year period

Aim

Evaluation of the emphasis on themes pertaining to paediatric radiology and radiation dose at the Meeting of the German Radiological Society from 1998 to 2008 in comparison to international data.

Materials and methods

Retrospective analysis of 9440 abstracts with documentation of type of contribution, imaging modality, and examined body region. Abstracts primarily dealing with paediatric radiology and those stating radiation dose were documented. Results were compared with a Pubmed query.

Results

448 contributions in paediatric radiology were presented corresponding to 5% of all abstracts with an increase from 5 (1998) to 7% (2008). The proportion of prospective studies of all congress contributions was 10%, whereas in paediatric radiology, the share of prospective studies was 6%. From 1998 to 2008, the share of MRI fell from 48 to 38%, while CT contributions rose from 30 to 34%. Within paediatric radiology, the proportion of CT rose from 23 to 29%, while MRI and ultrasound fell from 63 to 48% and 35 to 19%, respectively. The share of abstracts dealing with radiation dose rose from 7 to 10% while that primarily pertaining to dose reduction grew from 2 to 4%. Of all abstracts concerning CT, 15% touched on radiation dose, whereas 6% primarily dealt with dose reduction. Among all abstracts dealing with paediatric radiology, 20 and 6% mentioned radiation dose and dose reduction, respectively. In the subgroup of paediatric radiology CT abstracts, radiation dose and dose reduction were mentioned in 34 and 16%, respectively. An online query produced 137,791 publications on CT, of whose abstracts 3% mentioned radiation dose and 0.5% mentioned dose reduction. 11% of all CT publications dealt with paediatric populations and 2% of these publications examined questions of radiation dose.

Conclusions

In the last 11 years the Meeting of the German Radiological Society has presented a growing number of contributions pertaining to paediatric radiology. CT has shown the most pronounced growth of all contributions. Paediatric radiology has significantly more often dealt with questions of radiation exposure than those from general radiology. However, contributions with definite reference to radiation dose, both pertaining to all publications and specifically to those dealing with CT, remain a minority, albeit with a higher proportion when compared to international data.     

双能量CT肺灌注及血管成像与核素肺通气灌注成像诊断肺栓塞的对照研究

目的 通过与核素肺通气灌注显像比较,评价双能量CT肺血管成像(DE-CTPA)及双能量CT肺灌注成像(DE-CTLP)技术诊断肺栓塞的能力.方法 比较50例临床怀疑肺栓塞的患者DE-CTPA、DE-CTLP及核素肺通气灌注显像结果,以非线性相关检验比较DE-CTPA显示肺血管腔内充盈缺损与DE-CTLP显示灌注缺损之间的相关性,以核素为参考标准,应用一致性检验方法(Kappa检验)对照分析两者之间的一致性及DE-CTLP诊断肺栓塞的敏感性和特异性.结果 (1)50例临床怀疑肺栓塞患者中,4例CT图像质量差,不能评价.余46例共920个有效肺段中,DE-CTPA显示262个肺段肺血管腔内充盈缺损,DE-CTLP显示266个肺段明确灌注缺损.核素肺通气灌注扫描显示268个肺段灌注与通气不匹配.(2)DE-CTLP与DE-CTPA两者间显著相关(r=0.883,P<0.01);DE-CTLP与核素肺通气灌注显像的一致性良好(Kappa=0.940,P<0.01);以核素肺通气灌注成像为诊断参考标准,应用DE-CTLP诊断肺栓塞的阳性预测值95.5%(279/292),阴性预测值98.3%(641/652),敏感性96.2%(279/290),特异性98.0%(641/654).(3)应用CareDose 4D技术,DE-CTPA和DE-CTLP患者平均射线损伤剂量为(4.37±0.47)mSv.结论 应用DE-CTPA和DE-CTLP技术可以在一次扫描中同时获得常规CT肺血管成像的血管形态学信息和肺实质血流灌注情况,为临床诊断肺栓塞提供直观、有效的综合影像信息.     

Quantitative dual energy CT measurements in rabbit VX2 liver tumors: Comparison to perfusion CT measurements and histopathological findings

Purpose

To evaluate the correlation between quantitative dual energy CT and perfusion CT measurements in rabbit VX2 liver tumors.

Materials and methods

This study was approved by the institutional animal care and use committee at our institution. Nine rabbits with VX2 liver tumors underwent contrast-enhanced dual energy CT and perfusion CT. CT attenuation for the tumors and normal liver parenchyma and tumor-to-liver ratio were obtained at the 140 kVp, 80 kVp, average weighted images and dual energy CT iodine maps. Quantitative parameters for the viable tumor and adjacent liver were measured with perfusion CT. The correlation between the enhancement values of the tumor in iodine maps and perfusion CT parameters of each tumor was analyzed. Radiation dose from dual energy CT and perfusion CT was measured.

Results

Enhancement values for the tumor were higher than that for normal liver parenchyma at the hepatic arterial phase (P < 0.05). The highest tumor-to-liver ratio was obtained in hepatic arterial phase iodine map. Hepatic blood flow of the tumor was higher than that for adjacent liver (P < 0.05). Enhancement values of hepatic tumors in the iodine maps positively correlated with permeability of capillary vessel surface (r = 0.913, P < 0.001), hepatic blood flow (r = 0.512, P = 0.010), and hepatic blood volume (r = 0.464, P = 0.022) at the hepatic arterial phases. The effective radiation dose from perfusion CT was higher than that from DECT (P < 0.001).

Conclusions

The enhancement values for viable tumor tissues measured in iodine maps were well correlated to perfusion CT measurements in rabbit VX2 liver tumors. Compared with perfusion CT, dual energy CT of the liver required a lower radiation dose.     

Dual-energy CT angiography of chronic thromboembolic disease: Can it help recognize links between the severity of pulmonary arterial obstruction and perfusion defects?

Purpose

To evaluate whether dual-energy CT angiography (DE-CTA) could identify links between morphologic and functional abnormalities in chronic pulmonary thromboembolism (CPTE).

Materials and methods

Seventeen consecutive patients with CPTE without underlying cardio-respiratory disease were investigated with DE-CTA. Two series of images were generated: (a) transverse diagnostic scans (i.e., contiguous 1-mm thick averaged images from both tubes), and (b) perfusion scans (i.e., images of the iodine content within the microcirculation; 4-mm thick MIPs). Two radiologists evaluated by consensus the presence of: (a) pulmonary vascular features of CPTE and abnormally dilated systemic arteries on diagnostic CT scans, and (b) perfusion defects of embolic type on perfusion scans.

Results

Diagnostic examinations showed a total of 166 pulmonary arteries (166/833; 19.9%) with features of CPTE, more frequent at the level of peripheral than central arteries (8.94 vs 0.82; p < 0.0001), including severe stenosis with partial (97/166; 58.4%) or complete (20/166; 12.0%) obstruction, webs and bands (37/166; 22.3%), partial filling defects without stenosis (7/166; 4.2%), focal stenosis (4/166; 2.4%) and abrupt vessel narrowing (1/166; 0.6%). Perfusion examinations showed 39 perfusion defects in 8 patients (median number: 4.9; range: 1-11). The most severe pulmonary arterial features of CPTE were seen with a significantly higher frequency in segments with perfusion defects than in segments with normal perfusion (p < 0.0001). Enlarged systemic arteries were observed with a significantly higher frequency ipsilateral to lungs with perfusion defects (9/12; 75%) compared with lungs without perfusion defects (5/22; 22.7%) (p = 0.004).

Conclusion

Dual-energy CTA demonstrates links between the severity of pulmonary arterial obstruction and perfusion impairment, influenced by the degree of development of the systemic collateral supply.     

双能量CT肺灌注成像的定量参数诊断肺栓塞的临床应用价值

目的探讨双能量CT肺灌注成像(DEPI)的定量参数诊断肺栓塞的临床应用价值。方法选取40例疑似肺栓塞行双能量CT扫描并行CTPA及DEPI重建的患者影像资料,以肺段为评价单位,分析PE栓子的部位、栓塞程度以及肺灌注情况,测量感兴趣区的平均CT值及碘含量值与正常灌注区的比值,并进行统计学分析。结果40例患者分为非栓塞组13例,栓塞组24例,其他3例;栓塞组无栓塞肺段(201个)与非栓塞组肺段(200个)的平均CT值比值(t=-1.81,P>0.05)、碘含量比值(t=-1.541,P>0.05)差异无统计学意义;栓塞组栓塞肺段(204个)与无栓塞肺段(201个)的平均CT值比值(t=34.77,P<0.01)、碘含量比值(t=32.07,P<0.01)差异有统计学意义;栓塞组完全栓塞肺段(83个)与部分栓塞肺段(121个)的平均CT值比值(t=-17.54,P<0.01)、碘含量比值(t=-16.27,P<0.01)差异有统计学意义。ROC曲线分析显示DEPI定量参数对肺栓塞具有良好的诊断效能,平均CT值及碘含量值<40.65 HU、1.75 mg/ml临界值时,诊断PE的敏感度分别为96.0%、92.0%,特异度分别为88.6%、90.0%。结论DEPI定量参数能够作为诊断PE的有效指标,具有较高的敏感度和特异度,对PE治疗前后的评估提供更加全面、客观的依据。     

兔急性肺栓塞双源CT双能量肺灌注成像的动态变化及与病理对照

目的：动态观察家兔急性肺栓塞双源CT双能量肺灌注成像表现及其病理学基础,评价双源CT双能量肺灌注成像诊断家兔急性肺栓塞的价值。方法：经股静脉入路注入明胶海绵制作24只家兔急性肺栓塞模型,随机分成4组（即2h组、1天组、3天组和7天组）,每组6只。家兔栓塞前及栓塞后2h、1天、3天和7天行双源CT平扫和双能量扫描。采用双能量软件（LungPBV）进行数据分析处理,分别得到CT解剖图像（CTPA）、双能量肺灌注图像（DEPI）及两者融合图像。以肺叶为单位,分析栓塞前及栓塞后各时间点的肺灌注影像表现,并记录栓塞后肺内灌注异常的肺叶数目;进行家兔肺大体解剖和镜下观察,记录肺栓塞部位及病理表现。以病理为金标准,计算DEPI、CTPA及融合图像诊断肺栓塞的准确性。结果：栓塞前家兔双能量肺灌注图像表现为大致均匀的黄红色伪彩。栓塞后2h组肺灌注图像显示栓塞区呈蓝色;1天组及3天组栓塞区呈蓝黑色;7天组栓塞区呈黑色。DEPI和CTPA诊断肺栓塞的敏感度、特异度、阳性预测值（PPV）和阴性预测值（NPV）分别为100％、95％、95％和100％以及98％、100％、100％和99％;2项指标与病理结果吻合度强（Kappa值-0．933）,融合图像与DEPI一致性好。结论：采用双源CT双能量肺灌注成像技术可观察肺栓塞后肺实质动态灌注变化,并与病理结果有很高的一致性。     

Analysis of perfusion defects by causes other than acute pulmonary thromboembolism on contrast-enhanced dual-energy CT in consecutive 537 patients

Objective

To assess causes, incidence and patterns of perfusion defects (PDs) on dual-energy perfusion CT angiography (DECTA) in clinically suspected acute pulmonary thromboembolisms (PTE).

Materials and methods

Consecutive 537 patients who underwent DECTA for suspicion of PTE were retrospectively reviewed. After excluding patients with possible PTE or unsatisfactory perfusion map quality, 299 patients with 1697 lobes were included. The DECTA (Somatom Definition, Siemens) was performed at 140 kV and 80 kV. Color-coded perfusion images were obtained with a lung PBV application of the workstation software (Syngo Dual Energy). The presence, incidence, three patterns of PDs (wedge-shaped, heterogeneous, and regionally homogeneous), pulmonary diseases, and the matchedness between the PD and the disease extent were studied.

Results

315 of 1697 lobes (18.6%) in 156 of 299 patients (81.3%) showed PDs. Among them, 51 (3%), 257 (15.1%), and 7 (0.4%) lobes had PDs due to vascular, nonvascular, and unidentifiable causes, respectively. Vascular causes include: pulmonary arterial (PA) hypertension (0.7%), extrinsic occlusion of PA by fibrosis (0.6%), PA hypoplasia (0.6%), vasculitis (0.5%), cancer mass compressing PA, venous occlusion, AVM, and pulmonary angiosarcoma. Most of PDs were wedge-shaped and well-matched. Nonvascular causes include: mosaic attenuation (4.1%), emphysema (3.2%), interstitial fibrosis (1.6%), bronchitis (1.4%), GGO (1.2%), cellular bronchiolitis (1%), bronchiectasis, airway obstruction, compensaroty lung hyperinflation, air trapping, cor-pulmonale, bronchopneumonia, physiologic decreased ventilation, and segmental bronchial atresia. Most of PDs showed heterogeneous pattern and were not matched.

Conclusions

Various vascular and nonvascular diseases cause PDs on DECTA. Each disease shows different pattern of PD depending on pathophysiology and physiologic compensation.     

"Bubble-like" lung metastases in osteosarcoma patients

Purpose

Cavitation of pulmonary metastases have been reported by several authors either as a spontaneous phenomenon or as a consequence of chemotherapy. We present two cases, with this type of image in follow-up, and 20-45 months after the end of treatment. This was the first sign of pulmonary metastases.

Results

Two patients with osteogenic sarcoma developed radiological evidence of pulmonary “bubble-like” cavitation several years following completion of chemotherapy. In one patient the “bubble-like” cavitation transformed into a solid nodule. Both patients had surgical resections of all pulmonary lesions, and histology confirmed presence of viable osteosarcoma metastases.

Conclusion

The two cases suggest that onset of “bubble-like” cavitation in lung parenchyma of osteosarcoma patients may be the first sign of pulmonary metastases.     

16层螺旋CT与核素肺灌注/通气显像对肺动脉栓塞的诊断价值

目的　探讨 16层螺旋CT与核素肺灌注 /通气显像对急性肺动脉栓塞的诊断价值。方法　回顾 3 2例临床确诊的肺动脉栓塞病人的影像资料 (螺旋CT平扫加增强扫描 ,核素肺灌注 /通气显像扫描 ) ,进行对比分析。结果　螺旋CT增强检查的病变检出率为 90 .6% ,段级肺动脉栓塞受累率为 43 .2 % ,核素肺灌注 /通气显像检查病变检出率为 84.4% ,肺段栓塞受累率为 3 6.8%。结论　螺旋CT增强检查是观察肺动脉栓塞直接征象的理想方法 ,与核素肺显像相结合 ,更能全面分析病情。     

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.     

Assessment of pulmonary parenchyma perfusion with FAIR in comparison with DCE-MRI--initial results

Objective

The aim of this study was to assess pulmonary parenchyma perfusion with flow-sensitive alternating inversion recovery (FAIR) in comparison with 3D dynamic contrast-enhanced (DCE) imaging in healthy volunteers and in patients with pulmonary embolism or lung cancer.

Materials and methods

Sixteen healthy volunteers and 16 patients with pulmonary embolism (5 cases) or lung cancer (11 cases) were included in this study. Firstly, the optimized inversion time of FAIR (TI) was determined in 12 healthy volunteers. Then, FAIR imaging with the optimized TI was performed followed by DCE-MRI on the other 4 healthy volunteers and 16 patients. Tagging efficiency of lung and SNR of perfusion images were calculated with different TI values. In the comparison of FAIR with DCE-MRI, the homogeneity of FAIR and DCE-MRI perfusion was assessed. In the cases of perfusion abnormality, the contrast between normal lung and perfusion defects was quantified by calculating a normalized signal intensity ratio.

Results

One thousand milliseconds was the optimal TI, which generated the highest lung tagging efficiency and second highest PBF SNR. In the volunteers, the signal intensity of perfusion images acquired with both FAIR and DCE-MRI was homogeneous. Wedged-shaped or triangle perfusion defects were visualized in five pulmonary embolisms and three lung cancer cases. There was no significant statistical difference in signal intensity ratio between FAIR and DCE-MRI (P > 0.05). In the rest of eight lung cancers, all the lesions showed low perfusion against the higher perfused pulmonary parenchyma in both FAIR and DCE-MRI.

Conclusion

Pulmonary parenchyma perfusion imaging with FAIR was feasible, consistent and could obtain similar functional information to that from DCE-MRI.     

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.     

Visualization of morphological parenchymal changes in emphysema: comparison of different MRI sequences to 3D-HRCT

Purpose

Thin-section CT is the modality of choice for morphological imaging the lung parenchyma, while proton-MRI might be used for functional assessment. However, the capability of MRI to visualize morphological parenchymal alterations in emphysema is undetermined. Thus, the aim of the study was to compare different MRI sequences with CT.

Materials and methods

22 patients suffering from emphysema underwent thin-section MSCT serving as a reference. MRI (1.5 T) was performed using three different sequences: T2-HASTE in coronal and axial orientation, T1-GRE (VIBE) in axial orientation before and after application of contrast media (ce). All datasets were evaluated by four chest radiologists in consensus for each sequence separately independent from CT. The severity of emphysema, leading type, bronchial wall thickening, fibrotic changes and nodules was analyzed visually on a lobar level.

Results

The sensitivity for correct categorization of emphysema severity was 44%, 48% and 41% and the leading type of emphysema was identical to CT in 68%, 55% and 60%, for T2-HASTE, T1-VIBE and T1-ce-VIBE respectively. A bronchial wall thickening was found in 43 lobes in CT and was correctly seen in MRI in 42%, 33% and 26%. Of those 74 lobes presented with fibrotic changes in CT were correctly identified by MRI in 39%, 35% and 58%. Small nodules were mostly underdiagnosed in MRI.

Conclusion

MRI matched the CT severity classification and leading type of emphysema in half of the cases. All sequences showed a similar diagnostic performance, however a combination of HASTE and ce-VIBE should be recommended.     

Correlation analysis of dual-energy CT iodine maps with quantitative pulmonary perfusion MRI

AIM:To correlate dual-energy computed tomography(DECT) pulmonary angiography derived iodine maps with parameter maps of quantitative pulmonary perfusion magnetic resonance imaging(MRI).METHODS:Eighteen patients with pulmonary perfusion defects detected on DECT derived iodine maps were included in this prospective study and additionally underwent time-resolved contrast-enhanced pulmonary MRI [dynamic contrast enhanced(DCE)-MRI].DCE-MRI data were quantitatively analyzed using a pixel-by-pixel deconvolution analysis calculating regional pulmonary blood flow(PBF),pulmonary blood volume(PBV) and mean transit time(MTT) in visually normal lung parenchyma and perfusion defects.Perfusion parameterswere correlated to mean attenuation values of normal lung and perfusion defects on DECT iodine maps.Two readers rated the concordance of perfusion defects in a visual analysis using a 5-point Likert-scale(1 = no correlation,5 = excellent correlation).RESULTS:In visually normal pulmonary tissue mean DECT and MRI values were:22.6 ± 8.3 Hounsfield units(HU);PBF:58.8 ± 36.0 mL/100 mL per minute;PBV:16.6 ± 8.5 mL;MTT:17.1 ± 10.3 s.In areas with restricted perfusion mean DECT and MRI values were:4.0 ± 3.9 HU;PBF:10.3 ± 5.5 mL/100 mL per minute,PBV:5 ± 4 mL,MTT:21.6 ± 14.0 s.The differences between visually normal parenchyma and areas of restricted perfusion were statistically significant for PBF,PBV and DECT(P < 0.0001).No linear correlation was found between MRI perfusion parameters and attenuation values of DECT iodine maps(PBF:r = 0.35,P = 0.15;PBV:r = 0.34,P = 0.16;MTT:r = 0.41,P = 0.08).Visual analysis revealed a moderate correlation between perfusion defects on DECT iodine maps and the parameter maps of DCE-MRI(mean score 3.6,k 0.45).CONCLUSION:There is a moderate visual but not statistically significant correlation between DECT iodine maps and perfusion parameter maps of DCE-MRI.     

Quantitative assessment of cross-sectional area of small pulmonary vessels in patients with COPD using inspiratory and expiratory MDCT

Objectives

Structural and functional changes in pulmonary vessels are prevalent at the initial stages of chronic obstructive pulmonary disease (COPD). These vascular alterations can be assessed using cross-sectional area (CSA) of small pulmonary vessels. However, neither in non-COPD smokers nor in COPD patients it has been defined whether the structural changes of pulmonary vessels detected by paired inspiratory and expiratory CT scans are associated with emphysematous changes. We quantified the CSA and low attenuation area (LAA) and evaluated the changes in these parameters in the inspiratory and expiratory phases.

Materials and methods

Fifty consecutive non-COPD smokers and COPD patients were subjected to multi detector-row CT and the percentage of vessels with a CSA less than 5 mm² as well as the percentage LAA for total lung area (%CSA < 5, %LAA, respectively) were calculated.

Results

The %CSA < 5 correlated negatively with %LAA. The %CSA < 5 was lower in COPD patients with emphysema as compared with non-COPD smokers and COPD patients with or without mild emphysema. In addition, the %CSA < 5 was lower in the no/mild emphysema subgroup as compared with non-COPD smokers. The respiratory phase change of %CSA < 5 in COPD patients was greater than that in non-COPD smokers.

Conclusion

The percentage of small pulmonary vessels decreased as emphysematous changes increase, and this decrease was observed even in patients with no/mild emphysema. Furthermore, respiratory phase changes in CSA were higher in COPD patients than in non-COPD smokers.     

Validity of apparent diffusion coefficient hyperpolarized 3He-MRI using MSCT and pulmonary function tests as references

Purpose

To compare apparent diffusion coefficient (ADC) measurements from hyperpolarized (HP) helium (³He)-magnetic resonance imaging (MRI) with quantitative data from multislice Computed Tomography (CT) (MSCT) of the whole lungs and pulmonary function tests (PFT).

Materials and methods

Twenty-seven subjects, 22 with established emphysema and 5 with preclinical emphysema defined by PFT criteria, were examined with HP ³He-MRI and MSCT. Mean age was 55 (±12) years, 18 female and 9 male. Mean ADC from ³He-MRI was compared with emphysema index (EI), 15th percentile and mean lung density (MLD) values from MSCT. Both mean ADC and MSCT data were compared to PFT, especially percent of predicted diffusing capacity of carbon monoxide (%predicted DLCO), using Pearson's correlation test.

Results

Mean ADC and standard deviation values were 0.392 ± 0.119 cm²/s for the established emphysema group and 0.216 ± 0.046 for the pre-clinical emphysema group. MSCT values for the established emphysema group and pre-clinical emphysema group were: EI (%) 11 ± 12 and 0.4 ± 0.6, respectively; 15th percentile (Hounsfield Units (HU)), −956 ± 25 and −933 ± 13, respectively and MLD (HU) −877 ± 20 and −863 ± 15, respectively. Correlations between mean ADC and EI and 15th percentile were both r = 0.90 and for MLD r = 0.59. There was higher correlation between mean ADC and %predicted DLCO (r = 0.90) than between EI and %predicted DLCO (r = 0.76).

Conclusion

HP ³He-MRI correlates well with density measurements from MSCT and agrees better than MSCT with %predicted DLCO which is the PFT most related to emphysema.