Weight-Adjusted Contrast Administration in the Computed Tomography Evaluation of Pulmonary Embolism

IntroductionComputed tomography pulmonary angiogram (CTPA) is widely considered the gold standard for diagnosis of pulmonary embolism (PE) with previous studies demonstrating high sensitivity and specificity. Despite this, nondiagnostic and indeterminate CTPA rates of 5%–26% remain a concern. As part of a continuing quality assurance program, a new weight-adjusted contrast dose and increased administration rate CTPA protocol was studied with an aim to improve diagnostic accuracy of PE evaluation.MethodsA total of 2,398 CTPA examinations were reviewed to assess pulmonary arterial enhancement and PE yield in this retrospective study. Between 1 August 2014 and 1 August 2015, 1,133 patients received a fixed-volume (60 mL) contrast dose technique at 4 mL/s (protocol A). A new protocol was then implemented as part of a continuing quality assurance program. Between 15 September 2015 and 15 September 2016, 1,265 patients received a weight-adjusted contrast dose (1 mL/kg) and increased administration rate (5 mL/s) CTPA technique (protocol B). Studies were classed into categories based on quality of study; diagnostic: HU > 211, nondiagnostic: HU < 211 and PE yield; positive, negative, and indeterminate. These variables were compared with cross-sectional surface area to assess the relationship between patient habitus, CTPA diagnostic quality, and PE yield.ResultsA weight-adjusted contrast dose and increased administration rate CTPA protocol (protocol B) resulted in a significant increase in mean PA enhancement (P < .0001), 55.23% decrease in nondiagnostic studies and 43.04% decrease in indeterminate studies. Protocol B demonstrated increased positive and negative CTPA rates with decreased indeterminate rates from 12.38% to 7.04%. Comparison with cross-sectional area demonstrated significant increase in proportion of diagnostic studies and reduction in nondiagnostic and indeterminate CTPAs using protocol B in obese patients.ConclusionsA weight-adjusted contrast dose and increased administration rate CTPA protocol can significantly increase PA enhancement, especially in obese patients, resulting in greater high-quality and fewer nondiagnostic and indeterminate CTPA examinations. A CTPA protocol with a higher rate of conclusive examinations can provide greater confidence in PE evaluation for reporting radiologists and accurate clinical decision-making pathways for referring physicians.     

Prospective multicenter assessment of interobserver agreement for radiologist interpretation of multidetector computerized tomographic angiography for pulmonary embolism

Summary. Background: Emergency physicians rely on the interpretation of radiologists to diagnose and exclude pulmonary embolism (PE) on the basis of computerized tomographic pulmonary angiography (CTPA). Few data exist regarding the interobserver reliability of this endpoint. Objective: To quantify the degree of agreement in CTPA interpretation between four academic hospitals and an independent reference reading (IRR) laboratory. Methods: Hospitalized and emergency department patients who had one predefined symptom and sign of PE and underwent 64‐slice CTPA were enrolled from four academic hospitals. CTPA results as interpreted by board‐certified radiologists from the hospitals were compared against those from the IRR laboratory. CTPAs were read as indeterminate, PE^? or PE⁺, and percentage obstruction was computed by the IRR laboratory, using a published method. Agreement was calculated with weighted Cohen’s kappa. Results: We enrolled 492 subjects (63% female, age 54 ± 1 years, and 16.7% PE⁺ at the site hospitals). Overall agreement was 429/492 (87.2%; 95% confidence interval 83.9–90.0). We observed 13 cases (2.6%) of complete discordance, where one reading was PE⁺ and the other reading was PE^?. Weighted agreement was 92.3%, with kappa = 0.75. The median percentage obstruction for all patients was 9% (25th–75th percentile interquartile range: 5% to ? 30%). For CTPAs interpreted at the site hospitals as PE^? or indeterminate but read as PE⁺ by the IRR laboratory, the median of percentage obstruction was 6% (4–7%). Conclusion: We found in this sample a good level of agreement, with a weighted kappa of 0.75, but with 2.6% of patients having total discordance. Overall, a large proportion of clots were distal or minimally occlusive clots.     

Safety of ruling out acute pulmonary embolism by normal computed tomography pulmonary angiography in patients with an indication for computed tomography: systematic review and meta-analysis

Introduction : Several outcome studies have ruled out acute pulmonary embolism (PE) by normal computed tomography pulmonary angiography (CTPA). We performed a meta-analysis in order to determine the safety of this strategy in a specific group of patients with a strict indication for CTPA, that is, 'likely' or 'high' clinical probability for PE, an elevated D-dimer concentration, or both. Methods : Studies that ruled out PE by normal CTPA, with or without subsequent normal bilateral compression ultrasonography (CUS), in patients with a strict indication for CTPA, were searched for in Medline, EMBASE, Web of Science and the Cochrane dataset. The primary endpoint was the occurrence of (fatal) venous thromboembolism (VTE) in a 3-month follow-up period. Results : Three studies were identified that excluded PE by CTPA alone (2020 patients), and three studies that performed additional CUS of the legs after normal CTPA (1069 patients). The pooled incidence of VTE at 3 months was 1.2% [95% confidence interval (CI) 0.8–1.8] based on a normal CTPA result as a sole test, and 1.1% (95% CI 0.6–2.0) based on normal CTPA and negative CUS findings, resulting in negative predictive values of 98.8% (95% CI 98.2–99.2) and 98.9% (95% CI 98.0–99.4), respectively. This compares favorably with the VTE failure rate after normal pulmonary angiography (1.7%, 95% CI 1.0–2.7). The risk of fatal PE did not differ between the diagnostic strategies (0.6% vs. 0.5%). Conclusion : A normal CTPA result alone can safely exclude PE in all patients in whom CTPA is required to rule out this disease. There is no need for additional ultrasonography to rule out VTE in these patients.     

Diagnostic management of clinically suspected acute pulmonary embolism

Summary.  Current diagnostic management of hemodynamically stable patients with clinically suspected acute pulmonary embolism (PE) consists of the accurate and rapid distinction between the approximate 20–25% of patients who have acute PE and require anticoagulant treatment, and the overall majority of patients who do not have the disease in question. Clinical outcome studies have demonstrated that, using algorithms with sequential diagnostic tests, PE can be safely ruled out in patients with a clinical probability indicating PE to be unlikely and a normal D-dimer test result. This obviates the need for additional radiological imaging tests in 20–40% of patients. CT pulmonary angiography (CTPA) has become the first line tool to confirm or exclude the diagnosis of PE in patients with a likely probability of PE or an elevated D-dimer blood concentration. While single-row-detector technology CTPA has a low sensitivity for PE and bilateral compression ultrasound (CUS) of the lower limbs is considered necessary to rule out PE, multi-row-detector CTPA is safe to exclude PE without the confirmatory use of CUS.     

Clinical probability score and D-dimer estimation lack utility in the diagnosis of childhood pulmonary embolism

Summary.  Background : Childhood pulmonary embolism (PE) causes significant mortality and evidence suggests that it is under-diagnosed. Clinical probability scores and D-dimer estimation to assess pre-test probability have not been studied in children with suspected PE. Patients/Methods : This retrospective cohort study evaluated Wells simplified probability score for PE in 50 children with PE and 25 PE negative control patients, and D-dimer values in 27 PE positive and 12 PE negative children. Results : PE positive and PE negative groups had similar rates of risk factors for venous thromboembolism (VTE). Wells simplified probability score showed a small difference between PE positive and PE negative children (median score: PE positive, 4.5; PE negative, 4; P  =   0.009), children with PE are more likely to obtain a 'PE likely' score (score > 4), P  =   0.012. The difference was of slightly greater significance when the Wells score was adjusted to account for pediatric normal ranges for heart rate, P  =   0.007, and signs/symptoms of upper limb DVT, P  =   0.006. Children with PE were as likely as PE negative patients to have a D-dimer value within the normal range (PE positive, 15%; PE negative, 25%; P  =   0.654). A combination of a 'PE unlikely' score and normal D-dimer value occurred in 1/12 (8%) of PE negative children. Conclusions : The Wells clinical probability score and D-dimer estimation may lack utility in the determination of pre-test probability of PE in children. Validation of a pediatric clinical probability score, incorporating D-dimer estimation, by prospective study, would be difficult as a result of the rarity of childhood PE.     

Computed tomography pulmonary angiography in the diagnosis of acute pulmonary embolism in the emergency department

This study was undertaken to evaluate the use of computed tomography pulmonary angiography (CTPA) in patients with pulmonary embolism (PE) who were followed in the emergency department (ED). The files and computer records of 850 patients older than 16 years of age who were seen in the Hacettepe University Hospital ED between April 10, 2001, and December 1, 2005, and who required CTPA for PE prediagnosis and/or another diagnosis, were studied retrospectively. PE was identified by CTPA in 9.4% of 416 women and in 5.8% of 434 men. A significant difference (P< .05) was noted in the women and men in whom PE was detected. The mean age of the patients was 58.13±17.88 y (range, 16–100 y). Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for clinical susceptibility to PE among patients who underwent CTPA were assessed at 95.3%, 48.2%, 13%, and 99.2%, respectively. CTPA was done for different reasons: aortic aneurysm dissection (n=1), cough distinctive diagnosis (n=1), dyspnea distinctive diagnosis (n=6), chest pain distinctive diagnosis (n=3), PE prediagnosis (n=51), and other reasons (n=2). Also, sensitivity, specificity, PPV, and NPV were found to be 95.4%, 16.2%, 14.4%, and 96%, respectively, for D-dimer. CTPA, which is accessible on a 24-h basis in the ED, is a valuable tool for the diagnosis of PE.     

The use of D-dimer testing and Wells score in patients with high probability for acute pulmonary embolism

Rationale, aims and objective  To investigate if a combination of Wells pre-test probability score and D-dimer testing could be used as a safe base for making clinical decisions on further investigations for patients with intermediate to high risks of pulmonary embolism (PE).
Methods  One hundred and twenty patients with signs or symptoms of acute PE were investigated with pulmonary angiography (PA) or contrast enhanced computed tomography of the pulmonary arteries (CTPA), D-dimer testing (Tinaquant^®) and clinical scoring using the Wells pre-test probability score during their first 48 hours at the hospital. Patients were recruited consecutively from emergency departments at two teaching hospitals.
Results  The cut-off value of 0.5 mg L⁻¹ in D-dimer analysis is proved adequate with a negative predictive value (NPV) of 92% in this group of patients with intermediate to high risks. The combination of D-dimer testing and Wells score increases the NPV to 94%. The specificities of both tests were low.
Conclusion  D-dimer and Wells pre-test probability scores are safe to rule out acute PE even in patients with at least an intermediate risk of PE, but the specificity is low. D-dimer testing had a higher NPV than Wells score and the combination improved the algorithm further. The cut-off level for a high risk of PE measured with the Wells score was four and it seems reasonable to use that cut-off level in future algorithms. In addition, both PA and CTPA can present false positive and negative results difficult to interpret.     

The clinical course of pulmonary embolism patients anticoagulated for 1 year: results of a prospective, observational, cohort study

Summary.  Background : Few studies have examined the clinical course of pulmonary embolism (PE) in patients anticoagulated continuously for 1 year. Objective : We sought to determine the incidence of death, recurrent PE and bleeding during anticoagulation in the first year after acute PE, and to assess associated risk factors. Methods : All consecutive PE patients who were referred to our center in Pisa, Italy between 2001 and 2005 received a conventional initial treatment, followed by vitamin K antagonists [international normalized ratio (INR), 2.0–3.0] for 1 year. They were followed-up at scheduled times at the study center. The development of recurrent PE was objectively documented and recorded. Results : Out of 497 patients, 48 (9.6%) developed recurrent PE, which was fatal in 36. Of these 48 events, 39 occurred within 10 days of diagnosis and only two patients had a non-fatal recurrent PE between 6 and 12 months. Risk factors associated with the risk for overall recurrent PE were persistent severe dyspnoea ( P  =   0.007), a high perfusion defect score index (PDI) ( P  =   0.003) and cardiopulmonary co-morbidities ( P  =   0.005). Unprovoked presentation ( P  =   0.030), persistent severe dyspnoea ( P  =   0.011) and a high PDI ( P  =   0.001) predicted the risk for fatal PE. Overall bleeding incidence was 3.4%, no cases of bleeding occurred between 180 and 360 days post-diagnosis. Conclusions : In spite of conventional anticoagulation, a proportion of patients with PE experience both a fatal and non-fatal recurrent embolism within the first year. The large majority of these occur within the days proceeding diagnosis, with only a small minority occurring in the last 6 months. No bleeding was observed after 6 months. Therefore, prolonging anticoagulation for 1 year represents both a safe and effective treatment.     

CT肺动脉造影检测肺栓塞:采用容积螺旋穿梭技术捕捉最佳成像时相

目的探讨采用容积螺旋穿梭(VHS)技术进行肺动脉血管造影成像(CTPA)的临床应用价值。方法对研究组30例疑诊肺栓塞患者采用VHS进行CTPA成像,于开始注药后10s启动扫描,连续扫描4次(path)。回顾性分析对照组15例疑诊肺栓塞患者的64排CT常规CTPA资料,于注射对比剂后13～16s进行扫描。测量肺动脉主干、各段肺动脉的强化程度及主肺动脉的噪声,由2名医师按照5点评分法评价图像质量。结果研究组全部病例均成功配合完成检查,最佳path在第Ⅰ～Ⅳ个时相占比例分别为30.00%(9/30)、36.67%(11/30)、26.67%(8/30)、6.67%(2/30)。研究组平均MPA的CT值为(286±39)HU,对照组为(278±71)HU,差异无统计学意义(P=0.631)。研究组MPA最低强化值为240HU,对照组3例低于200HU。研究组肺段动脉可评价率平均为(88±14)%,高于对照组的(72±33)%(P=0.192)。对研究组图像质量及肺动脉强化两研究者一致性的Kappa值分别0.366、0.714,86.67%病例图像质量及90.00%肺动脉强化良好,均优于对照组(P均<0.05)。对图像噪声及运动伪影的主观评价两组间差异均无统计学意义。结论采用VHS技术有利于捕捉最佳肺动脉强化时相,是简单、实用的肺动脉血管造影方法。     

Ordering CT pulmonary angiography to exclude pulmonary embolism: defense versus evidence in the emergency room

Purpose

To identify reasons for ordering computed tomography pulmonary angiography (CTPA), to identify the frequency of reasons for CTPA reflecting defensive behavior and evidence-based behavior, and to identify the impact of defensive medicine and of training about diagnosing pulmonary embolism (PE) on positive results of CTPA.

Methods

Physicians in the emergency department of a tertiary care hospital completed a questionnaire before CTPA after being trained about diagnosing PE and completing questionnaires.

Results

Nine hundred patients received a CTPA during 3?years. For 328 CTPAs performed during the 1-year study period, 140 (43?%) questionnaires were completed. The most frequent reasons for ordering a CTPA were to confirm/rule out PE (93?%), elevated D-dimers (66?%), fear of missing PE (55?%), and Wells/simplified revised Geneva score (53?%). A positive answer for “fear of missing PE” was inversely associated with positive CTPA (OR 0.36, 95?% CI 0.14–0.92, p?=?0.033), and “Wells/simplified revised Geneva score” was associated with positive CTPA (OR 3.28, 95?% CI 1.24–8.68, p?=?0.017). The proportion of positive CTPA was higher if a questionnaire was completed, compared to the 2-year comparison period (26.4 vs. 14.5?%, OR 2.12, 95?% CI 1.36–3.29, p?p?=?0.067).

Conclusion

Reasons for CTPA reflecting defensive behavior—such as “fear of missing PE”—were frequent, and were associated with a decreased odds of positive CTPA. Defensive behavior might be modifiable by training in using guidelines.     

Assessing 2 d-dimer age-adjustment strategies to optimize computed tomographic use in ED evaluation of pulmonary embolism

Study ObjectiveValidate the sensitivity and specificity of 2 age adjustment strategies for d-dimer values in identifying patients at risk for pulmonary embolism (PE) compared with traditional d-dimer cutoff value (500 ng/mL) to decrease inappropriate computed tomography pulmonary angiography (CTPA) use.MethodsThis institutional review board–approved, Health Insurance Portability and Accountability Act-compliant retrospective study included all adult emergency department patients evaluated for PE over a 32-month period (1/1/11–8/30/13). Only patients undergoing CTPA and d-dimer testing were included. We used a validated natural language processing algorithm to parse CTPA radiology reports and determine the presence of acute PE. Outcome measures were sensitivity and specificity of 2 age-adjusted d-dimer cutoffs compared with the traditional cutoff. We used χ² tests with proportional analyses to assess differences in traditional and age-adjusted (age × 10 ng/mL) d-dimer cutoffs, adjusting both by decade and by year.ResultsA total 3063 patients with suspected PE were evaluated by CTPA during the study period, and 1055 (34%) also received d-dimer testing. The specificity of age-adjusted d-dimer values was similar or higher for each age group studied compared with traditional cutoff, without significantly compromising sensitivity. Overall, had decade age-adjusted cutoffs been used, 37 CTPAs could have been avoided (19.6% of 189 patients aged > 60 years with Wells score ≤ 4); had yearly age-adjusted cutoffs been used, 52 CTPAs (18.2% of 286 patients aged > 50 years with Wells score ≤ 4) could have been avoided.ConclusionEach age-adjusted d-dimer cutoff strategy for the evaluation of PE was associated with increased specificity and statistically insignificant decreased sensitivity when compared with the traditional d-dimer cutoff value.     

Subsegmental pulmonary embolism diagnosed by computed tomography: incidence and clinical implications. A systematic review and meta‐analysis of the management outcome studies

Summary. Background: Multiple‐detectors computed tomographic pulmonary angiography (CTPA) has a higher sensitivity for pulmonary embolism (PE) within the subsegmental pulmonary arteries as compared with single‐detector CTPA. Multiple‐detectors CTPA might increase the rate of subsegmental PE diagnosis. The clinical significance of subsegmental PE is unknown. We sought to summarize the proportion of subsegmental PE diagnosed with single‐ and multiple‐detectors CTPA and assess the safety of diagnostic strategies based on single‐ or multiple‐detectors CTPA to exclude PE. Patients and methods: A systematic literature search strategy was conducted using MEDLINE, EMBASE and the Cochrane Register of Controlled Trials. We selected 22 articles (20 prospective cohort studies and two randomized controlled trials) that included patients with suspected PE who underwent a CTPA and reported the rate of subsegmental PE. Two reviewers independently extracted data onto standardized forms. Results: The rate of subsegmental PE diagnosis was 4.7% [95% confidence interval (CI): 2.5–7.6] and 9.4 (95% CI: 5.5–14.2) in patients that underwent a single‐ and multiple‐detectors CTPA, respectively. The 3‐month thromboembolic risks in patients with suspected PE and who were left untreated based on a diagnostic algorithm including a negative CTPA was 0.9% (95% CI: 0.4–1.4) and 1.1% (95% CI: 0.7–1.4) for single‐ and multiple‐detectors CTPA, respectively. Conclusion: Multiple‐detectors CTPA seems to increase the proportion of patients diagnosed with subsegmental PE without lowering the 3‐month risk of thromboembolism suggesting that subsegmental PE may not be clinically relevant.     

Diagnosing pulmonary embolism: A question of too much choice?

The diagnosis of pulmonary embolism (PE) is difficult with many patients treated without the disease or left untreated without an adequate diagnostic work up. Recent advances in PE diagnosis are reviewed. The use of risk stratification in PE diagnosis is strongly recommended and evidence on how it can best be performed summarized. The Ginsberg/Wells stratification rule is recommended currently as the best validated rule. Computed tomographic pulmonary angiography (CTPA) was found to have quite poor sensitivity and to be poorly validated. It is recommended as adequate as a positive test in moderate/high risk groups and an exclusionary test in low risk groups or where an adequate alternative diagnosis is found. For D‐Dimer tests the only test with adequate sensitivity and validation in management studies is the VIDAS© D‐Dimer. This is in low/intermediate risk groups in the ED population. The Simpli‐Red© test is also reviewed but is too insensitive for most populations. Echocardiography: this is good in compromised patients as it is a bedside test which when negative virtually excludes PE. If positive in the right setting it has a high positive predictive value. A negative echocardiogram predicts a benign clinical course for PE. The rest of the paper details the authors approach to integrating these new techniques with established algorithms and where progress is likely to occur in the next few years. These include improvements in CTPA (plus the addition of CT venography), new point of care D‐Dimer tests, better risk stratification rules and integration of new strategies with artificial neural networks or computerized guidelines.     

CTPA对急性肺动脉栓塞程度及疗效的评价

目的：探讨CT肺血管造影（CTPA）对急性肺栓塞患者的栓塞程度及治疗前后右心功能参数变化评价的价值。方法：收集临床疑诊肺栓塞病例152例,纳入118例,所有病例均行CTPA检查,其中40例为非肺栓塞（WPE组）,肺动脉栓塞患者78例,后者结合临床表现分为严重栓塞42例（SPE组）,非严重栓塞36例（NSPE组）。SPE组立即行溶栓治疗,NSPE组则行抗凝治疗,于治疗14天后行CTPA复查。以CTPA作为肺栓塞的诊断依据,分析3组之间的心血管参数的差异;分析SPE组与NSPE组的栓塞指数,并探讨其与心血管参数之间的相关性;分析肺栓塞组治疗前后的心血管参数的差异。结果：SPE组的阻塞指数高于NSPE组;对心血管的参数分析发现,WPE组与栓塞组之间有显著性差异,SPE组与NSPE组之间亦有显著性差异。阻塞指数和心血管参数之间的相关性有统计学意义,其中右肺动脉管径与阻塞指数之间的相关系数最高。SPE组与NSPE组治疗前后的心血管参数均有统计学差异。结论：CTPA不仅可以诊断肺动脉栓塞,还可以反映肺栓塞后肺动脉的阻塞程度和右心功能的改变,从而反映预后,且可以观察疗效。     

急性肺栓塞CT肺动脉成像的研究进展

目前,CT肺动脉成像（CTPA）被认为是临床诊断急性肺栓塞（PE）的“金标准”。CTPA为诊断急性外周性PE提供了多方面的依据。但CTPA诊断急性外周性PE仍存在较大困难。目前CT辐射剂量及对比剂负荷为研究热点。本文对急性PE的CTPA诊断（尤其是外周性PE）、预后评估、CTPA技术进展等进行综述。     

双能量CT肺灌注在肺栓塞诊断及危险分层中的价值

  目的  探讨双能量CT肺灌注的灌注缺陷对肺栓塞诊断及危险分层。  方法  选取我院2018年1月~2020年12月157例临床疑诊为肺栓塞的患者为研究对象,最终120例患者确诊肺栓塞,所有患者均行双能量CT肺灌注成像(DEPI)及肺动脉CT血管造影成像(CTPA),根据临床生物学标志及影像学改变,将患者分为肺栓塞低危组(n=30)、中危组(n=35)、高危组(n=55)。比较患者肺栓塞数量,肺动脉灌注缺失面积分数、右/左心室短轴最大径比值及心脏生物学标志物。所有患者随访3月并记录结局。  结果  DEPI与CTPA对肺栓塞的诊断相符,诊断符合率为86.1%; CTPA和DEPI联合诊断的曲线下面积为0.95,特异性为89.20%,敏感度为95.80%,Youden指数为0.85,较CTPA和DEPI单独诊断肺栓塞更好。肺栓塞低危组、中危组、高危组的灌注缺损面积、心脏生物学标志物及右/左心室短轴最大径比值经两两比较差异有统计学意义(P < 0.05)。  结论  DEPI可作为CTPA的诊断肺栓塞的补充,并通过肺动脉灌注缺失面积分数危险分层,是一种新的临床诊疗方案的选择。      

Intraoperative pulmonary embolism and intracardiac thrombosis complicating liver transplantation: a systematic review

Summary.  Background:  Pulmonary embolism (PE) and intracardiac thrombosis (ICT) are rare but potentially lethal complications during orthotopic liver transplantation (OLT). Methods:  We aimed to review clinical and pathological correlates of PE and ICT in patients undergoing OLT. A systematic review of the literature was conducted using MEDLINE and ISI Web of Science. Results:  Seventy-four cases of intraoperative PE and/or ICT were identified; PE alone in 32 patients (43%) and a combination of PE and ICT in 42 patients (57%). Most frequent clinical symptoms included systemic hypotension and concomitant rising pulmonary artery pressure, often leading to complete circulatory collapse. PE and ICT occurred in every stage of the operation and were reported equally in patients with or without the use of venovenous bypass or antifibrinolytics. A large variety of putative risk factors have been suggested in the literature, including the use of pulmonary artery catheters or certain blood products. Nineteen patients underwent urgent thrombectomy or thrombolysis. Overall mortality was 68% (50/74) and 41 patients (82%) died intraoperatively. Conclusion:  Mortality was significantly higher in patients with an isolated PE, compared to patients with a combination of PE and ICT (91% and 50%, respectively; P  <   0.001). Intraoperative PE and ICT during OLT appear to have multiple etiologies and may occur unexpectedly at any time during the procedure.     

Increasing use of CTPA for the investigation of suspected pulmonary embolism

Objectives: Pulmonary embolism (PE) is a frequently suspected life-threatening condition that often presents with non-specific signs and symptoms. There is concern that increased availability of computerized tomography pulmonary angiogram (CTPA) is resulting in overuse in the diagnostic workup of patients presenting with cardio-respiratory symptoms. We therefore aimed to determine whether use of CTPA was increasing over time within our institution, with a consequent decrease in the diagnostic yield of PE. Furthermore, we investigated the frequency of alternative (non-PE) pathological findings revealed by CTPA.

Methods: All patients who underwent CTPA in the first 15 days of eight consecutive years were enrolled retrospectively. Radiology reports and online medical records were examined. In addition, the rates of incidental PE from patients undergoing CT chest for non-suspected PE indications were also examined.

Results: An increasing use of CTPA was confirmed (p = 0.04). Despite this, the diagnostic yield of PE also increased (p = 0.03). Similarly, increasing numbers of patients underwent CT chest for non-PE indications, but in this group the rate of incidental PE remained static (~3.4%). In CPTA investigations that were negative for PE, common alternative findings were consolidation, pleural effusion and emphysema, with only 16.7% showing no abnormality.

Conclusion: Although CTPA use is increasing, so is the diagnostic yield of PE. In contrast, the rate of incidental PE in those undergoing a CT chest scan for non-PE diagnosis remains relatively low and stable. This suggests that our observed increased use of CTPA is clinically appropriate.     

增强与非增强MR肺动脉血管成像诊断肺栓塞准确性的对比研究

目的比较对比增强MR血管成像(contrast-enhanced MR pulmonary angiography,CE-MRA)与非增强空间标记多反转脉冲序列(applying spatial labeling with multiple inversion pulses sequence,SLEEK)MR血管成像诊断肺栓塞(pulmonary embolism,PE)的准确性。材料与方法 26例CT肺动脉血管成像诊断肺栓塞的患者(男15例,女11例)于多排螺旋CT肺动脉造影(CT pulmonary angiography,CTPA)检查48 h内行CE-MRA以及非增强SLEEK MR检查。CTPA作为参考标准,计算并比较每种MR技术诊断肺栓塞的敏感性、特异性、阳性预测值以及阴性预测值。结果 CE-MRA诊断肺栓塞的敏感性为78.8%,特异性97.7%。非增强SLEEK MRI诊断肺栓塞的敏感性83.8%,特异性100%。两阅片者间存在高度一致性(k=0.87)。结论 CE-MRA和SLEEK MRI诊断肺栓塞的准确性无统计学差异,但非增强SLEEK MRI血管成像无需使用对比剂,有希望成为肺栓塞诊断策略中的一部分。     

光谱CT肺动脉成像定性诊断肺动脉栓塞及定量评估肺组织灌注

目的 观察光谱CT肺动脉成像(SCTPA)定性诊断肺动脉栓塞(PE)和定量评估肺组织灌注的价值。方法 回顾性分析37例临床诊断PE患者的CTPA资料,观察常规CTPA及SCTPA后处理图像,后者包括40 keV虚拟单能量图(VMI_{40 keV})、碘密度图(IDI)与有效原子序数(Z-eff)图的融合图及电子密度图(EDI);记录2种图像中肺段动脉、肺亚段及以下动脉内的栓子数量和位置,对比其中相应肺灌注缺损区与对侧相应正常肺实质区常规CT值、碘密度(ID)、Z-eff及电子密度(ED)的差异;针对差异有统计学意义的sCTPA参数绘制受试者工作特征(ROC)曲线,计算曲线下面积(AUC),评估其区分PE肺灌注缺损区与正常肺实质的效能。结果 37例中,仅以常规CTPA检出37个栓子,其中26个位于肺段动脉、11 个位于肺亚段及以下动脉;之后结合SCTPA后处理图像额外检出1个肺段动脉和2个肺亚段以下动脉内栓子。全部40个栓子对应肺灌注缺损区常规CT值高于、ID及Z-eff均低于对侧正常肺实质区(P均<0.01),而ED与正常肺实质区差异无统计学意义(P=0.54)。以常规CT值区分肺灌注缺损区与正常肺实质区的敏感度、特异度分别为42.50%及87.50%,以ID及Z-eff区分的敏感度分别为95.00%、97.50%,特异度均为100%。ID及Z-eff的AUC均为0.99,均高于常规CT值(0.65,Z=5.56、5.53,P均<0.01),而 ID与Z-eff的AUC差异无统计学意义(Z=0.71,P=0.48)。结论 利用SCTPA可提高PE检出率及定量评估肺组织灌注;根据ID及Z-eff可有效区分肺灌注缺损区与正常肺实质。