Multislice CT imaging of pulmonary embolism

Anticoagulant treatment for subsegmental pulmonary embolism

BACKGROUND

Acute pulmonary embolism (PE) is a common cause of death, accounting for 50,000 to 200,000 deaths annually. It is the third most common cause of mortality among the cardiovascular diseases, after coronary artery disease and stroke. The advent of multi-detector computed tomographic pulmonary angiography (CTPA) has allowed better assessment of PE regarding visualisation of the peripheral pulmonary arteries, increasing its rate of diagnosis. More cases of peripheral PEs, such as isolated subsegmental PE (SSPE) and incidental PE, have thereby been identified. These two conditions are usually found in patients with few or none of the classic PE symptoms such as haemoptysis or pleuritic pain, acute dyspnoea or circulatory collapse. However, in patients with reduced cardiopulmonary reserve, classic PE symptoms can be found with isolated SSPEs. Incidental SSPE is found casually in asymptomatic patients, usually by diagnostic imaging performed for other reasons (for example routine CT for cancer staging in oncology patients). Traditionally, all PEs are anticoagulated in a similar manner independent of their location, or number and size of the thrombi. It has been suggested that many patients with SSPE may be treated without benefit, increasing adverse events by a possible unnecessary use of anticoagulants. Patients with isolated SSPE, or incidental PE, may have a more benign clinical presentation compared to those with proximal PEs. However, the clinical significance in patients, and their prognosis, needs to be studied to evaluate whether anticoagulation therapy is required. This is the second update of the Cochrane systematic review published in 2014.

OBJECTIVES

To assess the effectiveness and safety of anticoagulation therapy versus control in patients with isolated subsegmental pulmonary embolism (SSPE) or incidental SSPE.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase, CINAHL and AMED databases and World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers to 26 November 2019. We also undertook reference checking to identify additional studies.

SELECTION CRITERIA

We included randomised controlled trials of anticoagulation therapy versus control in patients with SSPE or incidental SSPE.

DATA COLLECTION AND ANALYSIS

Two review authors inspected all citations identified to ensure reliable assessment. If relevant studies were identified, we planned for two review authors to independently extract data and to assess the methodological quality of identified trials using the criteria recommended in the Cochrane Handbook for Systematic Reviews of Interventions.

MAIN RESULTS

We did not identify any studies that met the inclusion criteria.

AUTHORS' CONCLUSIONS

There is no evidence from randomised controlled trials to assess the effectiveness and safety of anticoagulation therapy versus control in patients with isolated subsegmental pulmonary embolism (SSPE) or incidental SSPE. Well-conducted research is required before informed practice decisions can be made.

Anticoagulant treatment for subsegmental pulmonary embolism

BACKGROUND

Acute pulmonary embolism (PE) is a common cause of death, accounting for 50,000 to 200,000 deaths annually. It is the third most common cause of mortality among the cardiovascular diseases, after coronary artery disease and stroke.The advent of multi-detector computed tomographic pulmonary angiography (CTPA) has allowed better assessment of PE regarding visualisation of the peripheral pulmonary arteries, increasing its rate of diagnosis. More cases of peripheral PEs, such as isolated subsegmental PE (SSPE) and incidental PE, have thereby been identified. These two conditions are usually found in patients with few or none of the classic PE symptoms such as haemoptysis or pleuritic pain, acute dyspnoea or circulatory collapse. However, in patients with reduced cardio-pulmonary (C/P) reserve the classic PE symptoms can be found with isolated SSPEs. Incidental SSPE is found casually in asymptomatic patients, usually by diagnostic imaging performed for other reasons (for example routine CT for cancer staging in oncologic patients).Traditionally, all PEs are anticoagulated in a similar manner independent of the location, number and size of the thrombi. It has been suggested that many patients with SSPE may be treated without benefit, increasing adverse events by possible unnecessary use of anticoagulants.Patients with isolated SSPE or incidental PE may have a more benign clinical presentation compared with those with proximal PEs. However, the clinical significance in patients and their prognosis have to be studied to evaluate whether anticoagulation therapy is required.This review is an update of a Cochrane systematic review first published in 2014.

OBJECTIVES

To assess the effectiveness and safety of anticoagulation therapy versus no intervention in patients with isolated subsegmental pulmonary embolism (SSPE) or incidental SSPE.

SEARCH METHODS

The Cochrane Vascular Trials Search Co-ordinator searched the Specialised Register (last searched December 2015) and CENTRAL (2015, Issue 11). MEDLINE, EMBASE, LILACS and clinical trials databases were also searched.

SELECTION CRITERIA

Randomised controlled trials of anticoagulation therapy versus no intervention in patients with SSPE or incidental SSPE.

DATA COLLECTION AND ANALYSIS

Two review authors inspected all citations to ensure reliable selection. We planned for two review authors to independently extract data and to assess the methodological quality of identified trials using the criteria recommended in the Cochrane Handbook for Systematic Reviews of Interventions.

MAIN RESULTS

No studies were identified that met the inclusion criteria.

AUTHORS' CONCLUSIONS

There is no randomised controlled trial evidence for the effectiveness and safety of anticoagulation therapy versus no intervention in patients with isolated subsegmental pulmonary embolism (SSPE) or incidental SSPE, and therefore we can not draw any conclusions. Well-conducted research is required before informed practice decisions can be made.

Comprehensive CT cardiothoracic imaging: a new challenge for chest imaging

In the past, thoracic and cardiac imaging were two distinct specialties of radiology. The technical evolution, however, has changed their boundaries with an important impact on CT imaging practices and has opened the new era of "cardiothoracic" imaging, due to the strong anatomic, mechanical, physiologic, physiopathologic, and therapeutic cardiopulmonary correlations. Modern thoracic radiologists can no longer avoid the assessment of heart and coronary arteries, as they used to do with earlier generations of CT scanner. The advent of ECG gating and state-of-art CT scanner faster rotation speed, high spatial and temporal resolution, high-pitch mode, shorter acquisition time, and dedicated cardiac reconstruction algorithms has opened new possibilities for chest imaging, integrating cardiac morphologic and even functional information within a diagnostic chest CT scan. The aim of this review is to briefly show and summarize the concept of integrated cardiothoracic imaging, which redefines the boundaries of chest CT imaging, opening the door to a new radiologic specialty.

Anticoagulant treatment for subsegmental pulmonary embolism

BACKGROUND

Acute pulmonary embolism (PE) is a common cause of death, accounting for 50,000 to 200,000 deaths annually. It is the third most common cause of mortality among the cardiovascular diseases, after coronary artery disease and stroke.The advent of multi-detector computed tomographic pulmonary angiography (CTPA) has allowed better assessment of PE regarding visualisation of the peripheral pulmonary arteries, increasing its rate of diagnosis. More cases of peripheral PEs, such as isolated subsegmental PE (SSPE) and incidental PE, have thereby been identified. These two conditions are usually found in patients with few or none of the classic PE symptoms such as haemoptysis or pleuritic pain, acute dyspnoea or circulatory collapse. However, in patients with reduced cardio-pulmonary (C/P) reserve the classic PE symptoms can be found with isolated SSPEs. Incidental SSPE is found casually in asymptomatic patients, usually by diagnostic imaging performed for other reasons (for example routine CT for cancer staging in oncologic patients).Traditionally, all PEs are anticoagulated in a similar manner independent of the location, number and size of the thrombi. It has been suggested that many patients with SSPE may be treated without benefit, increasing adverse events by possible unnecessary use of anticoagulants.Patients with isolated SSPE or incidental PE may have a more benign clinical presentation compared with those with proximal PEs. However, the clinical significance in patients and their prognosis have to be studied to evaluate whether anticoagulation therapy is required.

OBJECTIVES

To assess the effectiveness and safety of anticoagulation therapy versus no intervention in patients with isolated subsegmental pulmonary embolism (SSPE) or incidental SSPE.

SEARCH METHODS

The Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched October 2013) and CENTRAL (2013, Issue 9). MEDLINE, EMBASE, LILACS and clinical trials databases were also searched (October 2013).

SELECTION CRITERIA

Randomised controlled trials of anticoagulation therapy versus no intervention in patients with SSPE or incidental SSPE.

DATA COLLECTION AND ANALYSIS

Two review authors inspected all citations to ensure reliable selection. We planned for two review authors to independently extract data and to assess the methodological quality of identified trials using the criteria recommended in the Cochrane Handbook for Systematic Reviews of Interventions.

MAIN RESULTS

No studies were identified that met the inclusion criteria.

AUTHORS' CONCLUSIONS

There is no randomised controlled trial evidence for the effectiveness and safety of anticoagulation therapy versus no intervention in patients with isolated subsegmental pulmonary embolism (SSPE) or incidental SSPE, and therefore we can not draw any conclusions. Well-conducted research is required before informed practice decisions can be made.

A novel method for pulmonary embolism detection in CTA images

In this paper, we propose a new computer-aided detection (CAD) - based method to detect pulmonary embolism (PE) in computed tomography angiography images (CTAI). Since lung vessel segmentation is the main objective to provide high sensitivity in PE detection, this method performs accurate lung vessel segmentation. To concatenate clogged vessels due to PEs, the starting region of PEs and some reference points (RPs) are determined. These RPs are detected according to the fixed anatomical structures. After lung vessel tree is segmented, the region, intensity, and size of PEs are used to distinguish them. We used the data sets that have heart disease or abnormal tissues because of lung disease except PE in this work. According to the results, 428 of 450 PEs, labeled by the radiologists from 33 patients, have been detected. The sensitivity of the developed system is 95.1% at 14.4 false positive per data set (FP/ds). With this performance, the proposed CAD system is found quite useful to use as a second reader by the radiologists.

Major vascular involvement in Behçet's disease: a retrospective study of 796 patients

Behçet's disease (BD) is a multi-systemic inflammatory disorder which can affect all types and sizes of blood vessels. This study aims to evaluate the prevalence and characteristics of vascular involvement in BD. Among 796 patients diagnosed with BD, 102 patients (81 male, 21 female) with vascular involvement were included, whose detailed clinical characteristics were recorded. The diagnosis of vascular lesions was made on clinical signs, by Doppler ultrasonography, and/or angiography using computed tomographic or magnetic resonance techniques. Vascular involvement occurred in 12.8 % of BD patients. Male to female ratio was 3.86:1. Mean age at onset of vascular involvement was 29.5 ± 11.3 years. Vascular lesion was the initial sign of BD in 28 patients, accounting for 27.5 %. Of 102 BD patients with vascular involvement, 72 had venous lesions (70.6 %) and 56 had arterial lesions (54.9 %), among which 26 (25.5 %) patients had both venous and arterial involvements. Female BD patients were more often involved with arterial lesions, whereas male BD patients developed venous lesions more often than females, P = 0.000. The most common type of vascular involvement was deep venous thrombosis in lower extremities (n = 49), other affected venous sites including inferior vena cava, superior vena cava, and cerebral venous. The prominent type of arterial lesions was dilatation (n = 25, including 24 cases of aneurysms); other types included eight cases of occlusion and 23 cases of stenosis. The main locations of arterial lesions were the aorta (n = 19), lower extremity arteries (n = 15), pulmonary arteries (n = 13), coronary arteries (n = 5), and subclavian arteries (n = 5). Compared with those without vascular lesions, ocular involvement, genital ulcers, and arthritis were significantly less frequent among patients with vasculo-BD (23.5 vs 35.2 %, P = 0.024; 54.9 vs 76.5 %, P = 0.000; 19.6 vs 30.5 %, P = 0.026), whereas a higher frequency of cardiac involvement was found in vasculo-BD patients (20.6 vs 3.6 %, P = 0.000). Vascular involvement is a complication in BD patients. This study illustrated that venous lesions are more frequently involved than arterial lesions. Vascular lesions correlated with a high frequency of cardiac involvement and a low incidence of ocular lesions, genital ulcers, and arthritis.

Pulmonary emboli after blunt trauma: timing, clinical characteristics and natural history

BACKGROUND

Venous thromboembolism (VTE) frequently complicates the recovery of trauma patients, and contributes to morbidity and mortality. Recent studies showed an increase in diagnosis of pulmonary embolism (PE) mainly in the early or immediate period after trauma. The clinical significance of those incidental PEs is unclear.

METHODS

The study cohort included all blunt trauma patients who had a contrast-enhanced CT of the chest performed as part of their initial trauma assessment from January 1, 2005 to January 31, 2007 in a large academic Canadian trauma centre. Patients diagnosed with PE at any point during admission were identified using our institutional trauma registry. All chest CT scans and electronic charts were reviewed. Patients were classified according to time of PE detection (immediate, early or late) and symptoms (asymptomatic or symptomatic). The clinical characteristics and hospital course of the patients who were diagnosed with immediate PE were described.

RESULTS

1259 blunt trauma patients were reviewed. Six patients presented with immediate PE (0.5%); nine patients were found to have early PE (0.7%) and 13 had late PE (1.0%). All six of the patients with immediate PE were classified as asymptomatic. Five of the nine patients with early PE were symptomatic and all 13 patients who developed late PE were symptomatic. Amongst the six patients with immediate PE, five survived 24h hospitalisation. Four of them were managed with prophylactic low molecular weight heparin and no other thromboembolic events were observed during admission or after discharge.

CONCLUSIONS

The increased use of advanced CT technology in trauma patients has resulted in an increased diagnosis of incidental PEs that are asymptomatic. The clinical significance and management of these small, incidental PE are uncertain and further studies are needed to clarify the natural history of this controversial finding.

Ventilation/perfusion imaging of the lung using ultra-short echo time (UTE) MRI in an animal model of pulmonary embolism

PURPOSE

To test the feasibility of ultra-short echo time (UTE) MRI for assessment of regional pulmonary ventilation/perfusion in a standard 3 Tesla clinical MRI system.

MATERIALS AND METHODS

MRI of the lungs was conducted with an optimized three-dimensional UTE sequence in normal rats and in a rat model of pulmonary embolism (PE) induced by a blood clot. Changes in signal intensities (SIs) due to inhalation of molecular oxygen or intravenous (i.v.) injection of Gd, which represents the distribution of ventilation and perfusion, respectively, were assessed in the lung parenchyma.

RESULTS

The UTE MRI with a TE of 100 μs could detect and map the changes in SI of the lung parenchyma due to the inhalation of 100% oxygen or i.v. injection of Gd in normal rats. Reduced T1 resulting from oxygen inhalation was also quantified. These changes were not observed on the images that were obtained simultaneously with a conventional range of TE (2.3 ms). Furthermore, the method could delineate the embolized lesions where the lung ventilation and perfusion were mismatched in a rat model with PE.

CONCLUSION

These results show the feasibility and diagnostic potential of UTE MRI for the assessment of pulmonary ventilation and perfusion which is essential for the evaluation of a variety of lung diseases.

The detection of pulmonary embolisms after a coronary artery bypass graft surgery by the use of 64-slice multidetector CT

The purpose of this study was to examine the incidence of pulmonary embolism (PE) after a coronary artery bypass graft (CABG) using 64-slice multidetector CT (MDCT), and to determine the correlations between the occurrence of a PE and the clinical or surgical parameters. Three hundred and twenty-six consecutive patients, who underwent coronary CT angiography using 64-slice MDCT to assess the graft patency after CABG, were enrolled in this study. Additional axial CT images, which were reconstructed by adopting a large field of view and thinner image slices, were reviewed for the presence of PE. The relationship between the occurrence of a PE and the type of surgery (off-pump CABG versus conventional CABG), number of target vessels, use of a saphenous vein graft, and length of stay in the intensive care unit (ICU) were evaluated. PE was detected on the CT images of 33 patients (10.1%), which involved the lobar or more proximal arteries in seven patients and the segmental or subsegmental arteries in 26. PE occurred more frequently after off-pump CABG (16.5%, 14/85) than after conventional CABG (7.9%, 19/241) (P = 0.024). Patients with PE were older (67 years vs. 62.7 years) and had longer stays in the ICU (5.6 days vs. 3.8 days) than those without (P = 0.013 and P = 0.007, respectively). No significant difference was observed in the number of target vessels and use of a saphenous vein graft between patients with and without an embolism. In a multi-variable analysis, the age of the patient, surgical methods, and ICU stay were independent predictors for the occurrence of PE (P = 0.013, P = 0.017, and P = 0.005, respectively). MDCT helps detect PE in patients after CABG. It is encountered more frequently after off-pump CABG than after conventional CABG and in older patients with longer ICU stays.

Dynamic MR perfusion imaging: capability for quantitative assessment of disease extent and prediction of outcome for patients with acute pulmonary thromboembolism

PURPOSE

To compare directly the capabilities of multidetector-row computed tomography (MDCT) and MRI for disease severity assessment and outcome prediction for acute pulmonary thromboembolism (APTE) patients.

MATERIALS AND METHODS

Fifty consecutive APTE patients underwent MDCT, MR angiography, dynamic perfusion MRI, treatment and follow-up examination. Pulmonary blood flow (PBF), pulmonary blood volume, and mean transit time maps were generated from perfusion MRI, and all segmental parameters were determined by using region of interest measurements. Receiver operator curve analyses were used to determine the most accurate parameter for diagnosis of the APTE segment. Then, APTE index from perfusion MRI (PE(perfusion MRI) index), right ventricle/left ventricle (RV/LV) diameter ratio and APTE indexes from embolic burdens observed on MDCT (PE(CT) index) and MR angiography (PE(MRA) index) were calculated. Finally, ability to differentiate mortality (n = 8) from survival (n = 42) groups and to predict patient outcome were statistically assessed.

RESULTS

PBF was a significantly more accurate parameter than others (P < 0.05). When feasible threshold value was applied, specificity and accuracy of RV/LV diameter ratio and PE(Perfusion MRI) index were significantly higher than those of PE(CT) and PE(MRA) indexes (P < 0.05). Logistic regression analysis demonstrated that each index was a significant predictor (P < 0.05).

CONCLUSION

Dynamic perfusion MRI can be effective for disease extent assessment and outcome prediction for APTE patients.

Unsuspected pulmonary embolism identified using multidetector computed tomography in hospital outpatients

AIM

To evaluate the incidence of unsuspected pulmonary embolism (PE) in an unselected population of outpatients undergoing contrast-enhanced multidetector computed tomography (MDCT) for indications other than the investigation of PE.

MATERIALS AND METHODS

Outpatients undergoing CT of the chest over a 6-month period were retrospectively identified and images reviewed. Inpatients and patients undergoing unenhanced CT of the chest were excluded. Data, including referring specialty, patient age and sex, reasons for examination, level of embolism, image quality, and section thickness were recorded. Radiology reports were reviewed with respect to whether or not the embolism was noted at the time of initial reporting.

RESULTS

Following exclusions 440 patients were reviewed (195 women and 245 men). PE was identified in 10 of the 440 patients, an incidence of 2.23%. One pulmonary embolus was in the main pulmonary artery, three were in lobar arteries, three in segmental arteries, and three in subsegmental arteries. Patients over the age of 60 years were more likely to have an embolism (9/300, 2.9%) compared with those under 60 years (1/140, 0.7%). Seven of the 10 positive examinations were carried out in patients who were known or later shown to have malignancy. Seven of the 10 emboli were reported at the time of initial reporting.

CONCLUSION

The outpatient population has a significant incidence of unsuspected PE. PE should be actively sought when reporting examinations performed for alternative indications, particularly where cancer is a known or suspected diagnosis.

Automatic detection of pulmonary embolism in CTA images

Pulmonary embolism (PE) is a common life-threatening disorder for which an early diagnosis is desirable. We propose a new system for the automatic detection of PE in contrast-enhanced CT images. The system consists of candidate detection, feature computation and classification. Candidate detection focuses on the inclusion of PE--even complete occlusions--and the exclusion of false detections, such as tissue and parenchymal diseases. Feature computation does not only focus on the intensity, shape and size of an embolus, but also on locations and the shape of the pulmonary vascular tree. Several classifiers have been tested and the results show that the performance is optimized by using a bagged tree classifier with two features based on the shape of a blood vessel and the distance to the vessel boundary. The system was trained on 38 CT data sets. Evaluation on 19 other data sets showed that the system generalizes well. The sensitivity of our system on the evaluation data is 63% at 4.9 false positives per data set, which allowed the radiologist to improve the number of detected PE by 22%.

64-Multidetector-row spiral CT in pulmonary embolism with emphasis on incidental findings

AIM

In this retrospective study, we assess the current role and future potential of computed tomography (CT) in the diagnostic algorithm of acute pulmonary embolism (PE).

MATERIALS AND METHODS

Two hundred patients underwent 64-multidetector-row spiral CT of the chest, pelvis, and thigh for suspected PE. CT scans were reviewed, and the degree of contrast enhancement and the presence of PE and/or (deep) venous thrombosis were recorded. In the case of PE, the level of thrombus was noted as central, main, or lobar. If the scan yielded a positive result for thrombosis, intravenous localization was also determined. Patient age, length of admission, clinical course, clinical indication, and incidental findings were registered as well.

RESULTS

PE was detected in 60 of the 200 patients with a high clinical probability of having PE (30%). Thirty-four patients had a positive CT scan result for venous thrombosis (17%). Twenty-four of the 60 patients had proximal deep venous thrombosis (40%), and 2 patients had arm venous thrombosis (3%). Thirty-four of the 60 patients had PE without venous thrombosis (57%). Eight of the 200 patients had deep venous thrombosis without suspicion of PE (4%). The distribution of the proximal thrombi showed 15 in a central artery (25%), 13 in a main pulmonary artery (22%), and 32 in a lobar segmental artery (53%). There was diffuse allocation of the thrombus in all lobes. Furthermore, CT scan noted a total of 120 incidental findings.

CONCLUSION

Our study indicates the potential clinical use of a diagnostic strategy for ruling out PE based on D-dimer testing and multidetector-row CT. A larger outcome study is needed before this approach can be adopted.

Computer tomography for venous thromboembolic disease

Venous thromboembolic disease is composed of two disease entities: pulmonary thromboembolism/pulmonary embolism and deep venous thrombosis. Clinical signs and symptoms of venous thromboembolic disease often are nonspecific and, as a result, the diagnosis may be difficult. If left untreated, pulmonary embolism can lead to a potentially fatal outcome. This article focuses on CT angiography as the diagnostic modality for thromboembolic pulmonary embolism and briefly discusses nonthromboembolic pulmonary embolism.

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.

Acute pulmonary embolism: Comparison of standard axial MDCT with paddlewheel technique

PURPOSE

The purpose of this study was to evaluate the ability of rotated paddlewheel reformations for the detection of central and peripheral pulmonary embolism (PE) compared to standard axial multi detector CT (MDCT) images.

MATERIAL AND METHODS

CT scans of 35 patients with PE were reviewed by three independent readers for the detection of pulmonary emboli using standard axial CT scans and reformatted paddlewheel technique. All images were evaluated in random order. MDCT examinations were performed with a collimation of 1.25 mm, a pitch of six and a reconstruction interval of 0.8mm. For each patient MIP were reformatted by using a paddlewheel arrangement with 5mm slab thickness and 5 degrees rotation. Standard of reference for PE was a consensus reading of the axial images by all three readers.

RESULTS

The overall sensitivity for the axial images for the three readers ranged between 91% and 96%; for paddlewheel reformations from 78% to 83%; the specificity for both methods was 98-99%. Inter- and intraobserver agreement was also higher for axial images than for paddlewheel reformations.

CONCLUSION

Comparing standard axial MDCT scans and reformatted paddlewheel images no significant difference for the detection of central PE was found, whereas for the detection of peripheral emboli standard axial images showed a significant higher percentage of detecting PE than paddlewheel reformations.

Prospective evaluation of unsuspected pulmonary embolism on contrast enhanced multidetector CT (MDCT) scanning

AIM

To quantify the incidence of unsuspected pulmonary emboli (PE) in an unselected inpatient population undergoing contrast enhanced multidetector CT (MDCT) scanning of the thorax and to assess aetiological factors in their development.

METHODS

All inpatients undergoing MDCT scanning of the thorax over a 10 month period were prospectively identified. Patients with previous or suspected current PE were excluded. CT scans were reviewed and the degree of contrast enhancement and presence of PE recorded. Where PE was found, the level of the most proximal thrombus was identified. Patient age, length of admission, slice scan thickness and clinical indication were noted.

RESULTS

547 inpatients who had undergone MDCT scanning were identified. Following exclusions 487 remained, 28 of whom (5.7%) had PE. Unsuspected PE was more common with increasing age, occurring in 9.2% (20/218) of all patients over 70 years and 16.7% (11/66) of those over 80 years (p<0.001). Eighteen of the 28 positive scans (64.3%) were at the segmental or subsegmental level. No other aetiological factor was identified which significantly increased the incidence of unsuspected PE. No significant difference was noted between 4-slice and 16-slice MDCT. Nine of the cases of incidental PE (32.1%) were not identified by the original reporting radiologists.

CONCLUSION

PE is an unsuspected finding on contrast enhanced MDCT scanning of the thorax in 5.7% of all inpatients. The incidence is higher in older patients. Most are peripheral and >30% are missed on initial review. PE should be routinely sought in all contrast enhanced MDCT scans of the chest, irrespective of the indication for the CT scan.

Multislice CT pulmonary findings in Behçet's disease (report of 16 cases)

Pulmonary artery aneurysm is the best-defined type of pulmonary disease in Behçet's disease (BD) with an important morbidity and mortality. The objective of this study was to assess the contribution of high-resolution dynamic chest CT imaging for one of the most serious aspects of BD: pulmonary artery aneurysm and other pulmonary parenchymal involvement. Sixteen BD patients were recruited for this study, (14 men, 87.5%, and 2 women, 12.5%). All patients fulfilled the 1990 American College of Rheumatology criteria for classification of BD [International Study Group for Behçet's Disease, Lancet 335:1078-1080, (1990)]. All patients underwent thorough history taking, full clinical examination, and routine laboratory investigations. Plain chest X-rays and pulmonary CT angiography were performed on all patients in an attempt to assess the pulmonary vasculature and lung parenchyma. Pulmonary vascular abnormalities were as follows: pulmonary artery aneurysms of varying sizes in nine patients (56.3%), main pulmonary artery ectasia in two patients (12.5%), pulmonary artery embolism in two patients (12.5%), venacaval thrombosis in seven patients (43.8%), and pulmonary venous varices in four patients (25%). Pulmonary parenchymal abnormalities were as follows: three patients (18.8%) with mild central bronchiectasis, one patient (6.3%) with atelectasis, one patient (6.3%) with subpleural nodule, and four patients (25%) with interstitial lung disease. Eight of the male patients were smokers. Multislice CT is useful in demonstrating the entire spectrum of thoracic manifestations of BD. Multislice CT is noninvasive and provides excellent delineation of the vessel lumen and wall and perivascular tissues, as well as detailed information concerning the lung parenchyma, pleura, and mediastinal structures.

Diagnosis of pulmonary emboli and image quality at CT pulmonary angiography: Influence of imaging direction with multidetector CT

AIM

To determine whether there was a significant difference in the prevalence of emboli detected when patients underwent computed tomography pulmonary angiography (CTPA) in a craniocaudal direction versus a caudocranial direction.

MATERIALS AND METHODS

This was a prospective study of 203 consecutive patients attending for CTPA for suspected pulmonary embolus. Imaging was performed on a multisection Siemens Volume Zoom CT machine, with bolus tracking centred on the main pulmonary artery after intravenous administration of contrast at 3 ml/s. Patients were examined in a single breath-hold, from the top of the aortic arch to the highest point of the diaphragm, in a randomly assigned cranio-caudal (group A), or caudo-cranial (group B) direction. Images were reviewed on a workstation in a cranio-caudal direction jointly by two radiologists unaware of the original imaging direction. The presence, number and position of arterial emboli were noted, and a subjective assessment of overall image quality and opacification of upper and lower lobe vessels (grade 1, 2, 3, or 4) was made.

RESULTS

Emboli were detected in 46 patients. There was no significant difference in the prevalence of emboli detected in the two groups [group A craniocaudal direction n=22, group B caudocranial direction n=24 (p=0.76)]. Imaging direction did not significantly influence overall image quality (p=0.07), however, there was a significantly greater proportion of patients in group A with grade 1 opacification of the upper lobe arteries (p=0.02).

CONCLUSION

Imaging direction does not significantly influence the diagnosis of pulmonary emboli but it does significantly improve the upper lobe pulmonary arterial enhancement with fewer non-diagnostic images, and on that basis we recommend that craniocaudal direction be used for CTPA studies.

Reproducibility of multi-detector spiral computed tomography in detection of sub-segmental acute pulmonary embolism

The aim of this study was to evaluate the inter-observer and intra-observer agreement of the diagnosis of sub-segmental acute pulmonary embolism (PE) in an inpatient population explored by 16 slice multi-detector spiral computed tomography (MDCT). Four hundred consecutive inpatients were referred for MDCT for the clinical suspicion of acute PE. One hundred and seventy seven (44.2%) had a known cardio-respiratory disease at the time of examination. Inter-observer and intra-observer agreements for the diagnosis of acute PE and of sub-segmental acute PE were assessed blind and independently by three experienced readers and by kappa statistics. Seventy-five patients were diagnosed as having acute PE findings (19.5%), and clots were located exclusively within sub-segmental arteries in nine patients (12%). When clots were limited to sub-segmental or more distal branches of the pulmonary arteries, kappa values were found to be moderate (0.56) to very good (0.85) for the diagnosis of sub-segmental acute PE, whereas for the diagnosis of acute PE in the whole population, kappa values ranged from 0.84 to 0.97. Intra-observer agreement was found to be perfect (kappa=1). MDCT is a reproducible technique for the diagnosis of sub-segmental acute PE as well as for acute PE. In this inpatient population, sub-segmental acute PE was not a rare event.

Severity assessment of acute pulmonary embolism: Role of CT angiography

Helical CT has gained wide acceptance in the noninvasive diagnosis of acute pulmonary embolism (APE) and has therefore largely replaced conventional pulmonary angiography as well as ventilation perfusion scan in the work-up of patients suspected of nonsevere pulmonary embolism (PE). Massive PE is life-threatening; its occurrence may require aggressive treatment such as thrombolysis or embolectomy. Identification of patients suffering from major thromboembolic events based solely on clinical grounds may, however, be difficult. Acute right heart failure is the principal cause of circulatory collapse and death for patients with massive PE, and rapid and specific diagnosis and therapy are required in such patients. Bedside echocardiography, a commonly performed first-line examination, demonstrates signs of cor pulmonale, if present, and can identify large central thrombi. However, echocardiography has limitations. In this review, our goal is to discuss the potential role of CT in assessing patients with severe APE. CT evaluation is based on the direct quantification of pulmonary arterial bed obstruction using various scores and the evaluation of morphological heart changes indicating acute cor pulmonale.

Features of cardiac disease demonstrated on CT pulmonary angiography

The heart and mediastinal structures can be overlooked at CT pulmonary angiogram (CTPA). This pictorial review will demonstrate the features of cardiac disease that may be evident on a CTPA. CTPA allows assessment of not only the pulmonary arteries for embolism, but also of the bronchi, lung parenchyma, mediastinum and heart. Co-existent underlying or incidental cardiac disease is often present. Potentially life-threatening alternative diagnoses in a patient with chest symptoms can be reliably identified. Pathologies of the myocardium including hypertrophic cardio myopathy, pericardial disease, valvular disease, coronary artery disease, and intracardiac abnormalities are demonstrated pictorially. CTPA is increasingly used for the detection of pulmonary embolism. Most patients investigated have pathology other than PE as a cause of their symptoms. Frequently information about the heart is produced that provides important clues to determine the cause for the presenting symptoms and signs or reveals co-existing pathology. It is important to have a clear understanding of the features of cardiac disease which may be seen on a CTPA.

MR angiography with sensitivity encoding (SENSE) for suspected pulmonary embolism: comparison with MDCT and ventilation-perfusion scintigraphy

OBJECTIVE

The aim of our study was to determine the utility of time-resolved contrast-enhanced MR angiography combined with sensitivity encoding (SENSE) for patients with pulmonary embolism. SUBJECTS AND METHODS. Forty-eight consecutive patients (26 men and 22 women; age range, 27-73 years; mean age, 55 years) with suspected pulmonary embolism underwent chest radiography, contrast-enhanced MDCT, MR angiography with SENSE, ventilation-perfusion scintigraphy, and pulmonary angiography. MR angiography with SENSE was performed using IV administration of gadolinium contrast medium with a 3D turbo field-echo pulse sequence (TR/TE, 4.0/1.2; flip angle, 30 degrees ) on a 1.5-T scanner. Capabilities of diagnosing pulmonary embolism using MR angiography (data set A), contrast-enhanced MDCT (data set B), contrast-enhanced MDCT with MR angiography (data set C), ventilation-perfusion scintigraphy (data set D), and contrast-enhanced MDCT with ventilation-perfusion scintigraphy (data set E) were determined by receiver operating characteristic analysis, using the results of pulmonary angiography as the reference standard. The diagnostic capability of each data set was analyzed on a per-vascular zone and a per-patient basis with the McNemar test.

RESULTS

Sensitivity and specificity of data set A were 83% and 97%, respectively, on a per-vascular zone basis and 92% and 94%, respectively, on a per-patient basis. Specificity and accuracy of data set A were significantly higher than those of data set D on a per-patient basis (p < 0.05).

CONCLUSION

Time-resolved MR angiography with SENSE is effective for the diagnosis of pulmonary embolism.

ECG-gated multislice spiral CT for diagnosis of acute pulmonary embolism

AIM

The purpose of this study was to determine the feasibility of echocardiogram (ECG)-gated multi-slice CT angiography (MCTA) in patients with clinical suspicion of acute venous thromboembolism (VTE), to investigate the effect of ECG-gating on cardiac motion artefacts, and to determine the diagnostic reader agreement of ECG-gated MCTA in comparison with conventional MCTA.

MATERIALS AND METHODS

Forty-eight consecutive patients were prospectively enrolled and randomly underwent ECG-gated (n=25, group 1) or non-ECG-gated (n=23, group 2) eight-slice pulmonary MCTA. Image data were evaluated by three independent chest radiologists with respect to the presence or absence of emboli at different arterial levels (main, lobar, segmental, and subsegmental arteries), and with regard to cardiac motion artefacts. Statistical tests used to calculate inter-observer agreement were weighted kappa statistics, extended kappa statistics and confidence indices indicating three-reader agreement accuracy.

RESULTS

Twenty-seven patients (56.3%) were diagnosed to have pulmonary embolism (13 from group 1, 14 from group 2). Cardiac motion artefacts were significantly more frequent in group 2 (70% in group 2 versus 13% in group 1, p=0.0001). The overall diagnostic agreement was excellent with both MCTA techniques (three-reader confidence index for all vascular territories: 0.76 and 0.84 for groups 1 and 2, respectively (extended kappa=0.69 and 0.78, respectively); three-reader confidence index for diagnosis of VTE: 0.94 and 0.85 for groups 1 and 2, respectively (extended kappa=0.91 and 0.73, respectively), weighted kappa=0.81-0.83 and 0.92-0.95 for groups 1 and 2, respectively, and did not differ significantly between the two groups. In addition there was no significant difference of inter-observer agreement in either group at any assessed pulmonary arterial level.

CONCLUSION

ECG-gated pulmonary MCTA is feasible in patients with clinical suspicion of VTE. However, ECG-gated image acquisition did not influence the diagnostic reader agreement accuracy and inter-observer agreement of MCTA. Hence, it does not appear to be advantageous for the MCTA diagnosis of pulmonary embolism.

Azygos arch valves: prevalence and appearance at contrast-enhanced CT

PURPOSE

To evaluate the prevalence and appearance of azygos arch valves at intravenous contrast material-enhanced computed tomography (CT).

MATERIALS AND METHODS

Findings of 309 intravenous contrast-enhanced spiral CT examinations of the chest were retrospectively reviewed. The presence of contrast material reflux into the azygos arch and of a focal bulge in the azygos arch was recorded. An azygos valve was considered present if contrast material with a curvilinear posterior contour was seen in the azygos arch. The chi2 test was used to compare the frequency of contrast material reflux into the azygos vein for high and low rates of contrast material injection and for right and left arm injection.

RESULTS

Reflux of contrast material into the azygos arch occurred at 154 (49.8%) of 309 examinations, and valves were seen on images of 105 (68.2%) examinations. A focal bulge was seen in the azygos arch on images of 86 (81.9%) of 105 examinations with an azygos valve. Contrast material refluxed more frequently into the azygos vein in examinations with high rates of injection (83 of 128 examinations, 64.8%) than in those with low rates of injection (71 of 181, 39.2%, P <.001). Among the patients with high rates of injection, contrast material refluxed more frequently into the azygos vein with the right arm injection than with left arm injection (53 of 70, 76% vs 30 of 58, 52%, P <.01). Refluxed contrast material appeared as discrete collections within cusps of the azygos valves on images of 69 (44.8%) of 154 examinations.

CONCLUSION

Valves in the azygos arch are common and more frequently seen at CT when high injection rates and right arm injections are used.

Increased prevalence of coronary artery calcification in patients with suspected pulmonary embolism

RATIONALE AND OBJECTIVES

The authors explored the possibility that patients with suspected pulmonary embolism are at high risk for coronary artery disease. To this purpose, they compared the presence of coronary artery calcification on computed tomography (CT) in patients suspected of pulmonary embolism with age- and gender-matched controls.

MATERIALS AND METHODS

The CT scans of 214 patients were reviewed. Of those, 107 consecutive patients (50%) had pulmonary CT angiography for suspected pulmonary embolism (PE group). The remaining 107 age- and gender-matched patients were scanned for reasons other than pulmonary embolism (non-PE group). All CT scans were performed with the same 8-detector-row multislice scanner. Two radiologists reviewed scans of 5-mm slices using a five-grade modified coronary calcium scoring system: 1 = no calcification; 2 = minimal calcification; 3 = mild calcification; 4 = moderate calcification; and 5 = severe calcification. The Marginal Homogeneity test was used to compare the distribution and severity of calcification in the two groups.

RESULTS

Of 107 patients in the PE group, seven (6.54%) had pulmonary embolism detected on CT. Coronary artery calcification was detected in 61 patients (57%) in the PE group compared with 42 patients (39%) in the non-PE group. The Marginal Homogeneity test showed that patients with pulmonary embolism symptoms were 2.9 times more likely to have calcification detected compared with those patients who had chest CT for some other reason (P = .0034). However, in patients in whom coronary artery calcification was detected, the distribution of severity of calcification was the same in both groups.

CONCLUSION

Assuming coronary artery calcification indicated coronary atherosclerosis, patients undergoing CT for suspected pulmonary embolism may be at high risk for coronary artery disease.

Severity assessment of acute pulmonary embolism: evaluation using helical CT

The objective was to evaluate the helical CT (HCT) criteria that could indicate severe pulmonary embolism (PE). In a retrospective study, 81 patients (mean age 62 years) with clinical suspicion of PE explored by HCT were studied. The patients were separated into three different groups according to clinical severity and treatment decisions: group SPE included patients with severe PE based on clinical data who were treated by fibrinolysis or embolectomy ( n=20); group NSPE included patients with non-severe PE who received heparin ( n=30); and group WPE included patients without PE ( n=31). For each patient we calculated a vascular obstruction index based on the site of obstruction and the degree of occlusion in the pulmonary artery. We noted the HCT signs, i.e., cardiac and pulmonary artery dimensions, that could indicate acute cor pulmonale. According to multivariate analysis, factors significantly correlated with the severity of PE were: the vascular obstruction index (group SPE: 54%; group NSPE: 24%; p<0.001); the maximum minor axis of the left ventricle (group SPE: 30.2 mm; group NSPE: 40.4 mm; p<0.001); the diameter of the central pulmonary artery (group SPE: 32.4 mm; group NSPE: 28.3 mm; p<0.001); the maximum minor axis of the right ventricle (group SPE: 47.5 mm; group NSPE: 42.7 mm; p=0.029); the right ventricle/left ventricle minor axis ratio (group SPE: 1.63; group NSPE: 1.09; p<0.0001). Our data suggest that hemodynamic severity of PE can be assessed on HCT scans by measuring four main criteria: the vascular obstruction index; the minimum diameter of the left ventricle; the RV:LV ratio; and the diameter of the central pulmonary artery.

Diagnosis of pulmonary embolism with spiral CT as a second procedure following scintigraphy

Our objective was to evaluate, in a routine clinical setting, the role of spiral CT as a second procedure in patients with clinically suspected pulmonary embolism (PE) and abnormal perfusion scan. We prospectively studied the role of spiral CT in 279 patients suspected of PE. All patients started their diagnostic algorithm with chest radiographs and perfusion scintigraphy. Depending on the results of perfusion scintigraphy, patients proceeded to subsequent levels in the algorithm: stop if perfusion scintigraphy was normal; CT and pulmonary angiography if subsegmental perfusion defects were seen; ventilation scintigraphy followed by CT when segmental perfusion defects were seen; and pulmonary angiography in this last group when results of ventilation/perfusion scintigraphy and CT were incongruent. Reference diagnosis was based on normal perfusion scintigraphy, high probability perfusion/ventilation scintigraphy in combination with abnormal CT, or pulmonary angiography. If PE was present, the largest involved branch was noted on pulmonary angiography, or on spiral CT scan in case of a high-probability ventilation/perfusion scan and a positive CT scan. A distinction was made between embolism in a segmental branch or larger, or subsegmental embolism. Two hundred seventy-nine patients had abnormal scintigraphy. In 27 patients spiral CT and/or pulmonary angiography were non-diagnostic and these were excluded for image analysis. Using spiral CT we correctly identified 117 of 135 patients with PE, and 106 of 117 patients without PE. Sensitivity and specificity was therefore 87 and 91%, respectively. Prevalence of PE was 53%. Positive and negative predictive values were, respectively, 91 and 86%. In the high-probability group, sensitivity and specificity increased to 97 and 100%, respectively, with a prevalence of 90%. In the non-high probability-group sensitivity and specificity decreased to 61 and 89%, respectively, with a prevalence of 25%. In a routine clinical setting single-detector spiral CT technology has limited value as a second diagnostic test because of low added value in patients with a high-probability lung scan and low sensitivity in patients with non-high-probability lung scan result.

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 VIDASCopyright D-Dimer. This is in low/intermediate risk groups in the ED population. The Simpli-RedCopyright 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.

What happens after a lung scan? Management and outcome of patients in a regional hospital

Pulmonary embolism (PE) remains a common preventable cause of death in hospitalized patients. The purpose of this study is to examine the in-hospital management, complications of treatment and clinical outcomes of inpatients undergoing lung scintigraphy for the diagnosis of PE in a regional hospital. Two hundred consecutive inpatients with suspected PE were enrolled. The results of lung scans, stratified according to the probability of pulmonary embolism, were correlated with anticoagulation status, discharge diagnosis, haemorrhagic complications and clinical outcome at 6 months. The use of complementary imaging investigations was also determined. Other imaging was performed infrequently (Doppler ultrasound in 18% of patients, CT pulmonary angiography (CT-PA) in 0.5% and conventional pulmonary angiography in 4% of patients). Long-term anticoagulation was initiated in 66 patients (33%), including 10 with intermediate probability lung scans (IPLS) who had no further investigations. Major haemorrhage occurred in 14% of all long-term anticoagulated patients followed up. The recognized recurrence rate was very low (3%) and there was no documented mortality from PE. Most patients with suspected PE are treated on the basis of the lung scan result without further tests. However, other imaging (especially CT-PA and conventional pulmonary angiography) should be performed prior to anticoagulation in patients with IPLS in whom the diagnosis is in doubt. Standard anticoagulation for 6 months appears to be effective for PE, and the recurrence rate is low. However, it has a significant risk of major haemorrhagic complications.