Helical CT for the Evaluation of Acute Pulmonary Embolism

Comparison of Dual-Energy Computed Tomography Pulmonary Angiography-Derived Contrast Enhancement with Standard Dual-Energy Pulmonary Angiography in Diagnosing Subsegmental Pulmonary Embolism: A Prospective Study

Objective  In this study, we compare the diagnostic accuracy of dual-energy (DE) computed tomography pulmonary angiography (CTPA) derived contrast enhancement (DECTPA, CTPA images with iodine maps) with standard dual-energy pulmonary angiography (SCTPA) for diagnosis of subsegmental pulmonary embolism in the cases with clinical suspicion of acute pulmonary embolism (APE). Materials and Methods  We included 50 cases with clinical suspicion of APE that were referred for CTPA. All the patients underwent CTPA in the dual-energy protocol. Two radiologists evaluated the images. The first radiologist interpreted the SCTPA images (vascular images) and the second radiologist interpreted the DECTPA (CTPA images with iodine maps) for findings of APE. We calculated the sensitivity, specificity, and negative predictive value of DECTPA vis-à-vis SCTPA images. Results  The DECTPA with the advantage of iodine map utilization yielded higher detection of thrombi in peripheral subsegmental arteries (72 vs. 99; p  = - 0.001) as compared to the SCTPA images by identification of 18 new perfusion defects (interquartile range [IQR]: 0-1) that were consistent with APE. Filling defects were identified in 27 (IQR: 0-4) more subsegmental arteries supplying these 18 areas, which were not detected on SCTPA alone. These 18 perfusion defects were identified in 13 cases. In these 13 cases, 4 new cases were diagnosed that were negative on CTPA ( p  = -0.125). In the evaluation of the APE, sensitivity and specificity were calculated and it was found that DECTPA showed 100% sensitivity and 86% specificity with 100% negative predictive value in the detection of thrombi as compared to the routine CTPA. Conclusion  DECTPA has higher sensitivity and negative predictive value in the detection of the subsegmental perfusion defect identification as compared to SCTPA.

CT pulmonary angiography: optimising acute thoracic imaging by fixed-timing contrast medium delivery with a modified breathing instruction

AIM

To compare the thoracic vascular opacification achieved using the standard bolus-tracking protocol (BTP) with a fixed-timing protocol (FTP) with a modified breathing instruction during computed tomography pulmonary angiography (CTPA) examinations.

MATERIALS AND METHODS

A single-centre review of CTPA examinations performed between July 2018 and January 2019 using the BTP or FTP and weight-based contrast dosing of 20 mg iodine/kg body weight/s for 20 seconds at 100 kV tube potential. Radiodensity (in Hounsfield units) was analysed in the right ventricle, main pulmonary artery (MPA), left atrium, left ventricle, and ascending and descending thoracic aorta (DTA). A p-value of <0.05 was considered significant.

RESULTS

Of 782 examinations, 88 BTP and 90 FTP examinations were included. Mean attenuation of the MPA was similar in the FTP (396 ± 106 HU) and BTP (362 ± 119 HU; p=0.06); however, good-quality (≥250 HU) MPA opacification was achieved in more FTP examinations (87/90, 96.7%) compared to the BTP (73/88, 82.9%; p=0.002). Mean attenuation of the DTA was better in the FTP (325 ± 72 HU) than the BTP (228 ± 75 HU; p <0.0001), with good-quality opacification (≥250 HU) in 76/90 (84.4%) FTP examinations compared with 36/88 (40.9%) BTP examinations (p <0.001).

CONCLUSION

The FTP achieves better opacification of the MPA and DTA compared to the BTP.

Quantitative Imaging Metrics for the Assessment of Pulmonary Pathophysiology: An Official American Thoracic Society and Fleischner Society Joint Workshop Report

Multiple thoracic imaging modalities have been developed to link structure to function in the diagnosis and monitoring of lung disease. Volumetric computed tomography (CT) renders three-dimensional maps of lung structures and may be combined with positron emission tomography (PET) to obtain dynamic physiological data. Magnetic resonance imaging (MRI) using ultrashort-echo time (UTE) sequences has improved signal detection from lung parenchyma; contrast agents are used to deduce airway function, ventilation-perfusion-diffusion, and mechanics. Proton MRI can measure regional ventilation-perfusion ratio. Quantitative imaging (QI)-derived endpoints have been developed to identify structure-function phenotypes, including air-blood-tissue volume partition, bronchovascular remodeling, emphysema, fibrosis, and textural patterns indicating architectural alteration. Coregistered landmarks on paired images obtained at different lung volumes are used to infer airway caliber, air trapping, gas and blood transport, compliance, and deformation. This document summarizes fundamental "good practice" stereological principles in QI study design and analysis; evaluates technical capabilities and limitations of common imaging modalities; and assesses major QI endpoints regarding underlying assumptions and limitations, ability to detect and stratify heterogeneous, overlapping pathophysiology, and monitor disease progression and therapeutic response, correlated with and complementary to, functional indices. The goal is to promote unbiased quantification and interpretation of in vivo imaging data, compare metrics obtained using different QI modalities to ensure accurate and reproducible metric derivation, and avoid misrepresentation of inferred physiological processes. The role of imaging-based computational modeling in advancing these goals is emphasized. Fundamental principles outlined herein are critical for all forms of QI irrespective of acquisition modality or disease entity.

Pitfalls in the imaging of pulmonary embolism

Pulmonary embolism (PE) can present with a wide spectrum of clinical symptoms that can overlap considerably with other cardiovascular diseases. To avoid PE related morbidity and mortality, it is vital to identify this disease accurately and in a timely fashion. Several clinical criteria have been developed to standardize the diagnostic approach for patients with suspected PE. Computed tomographic pulmonary angiogram has significantly improved the detection of pulmonary embolism and is considered the imaging modality of choice to diagnose this disease. However, there are several potential pitfalls associated with this modality which can make diagnosis of PE challenging. In this review, we will discuss various pitfalls routinely encountered in the diagnostic work up of patients with suspected PE, approaches to mitigate these pitfalls and incidental pulmonary embolism.

Mortality and Pulmonary Embolism in Acute Respiratory Distress Syndrome From COVID-19 vs. Non-COVID-19

Purpose

There may be a difference in respiratory mechanics, inflammatory markers, and pulmonary emboli in COVID-19 associated ARDS vs. ARDS from other etiologies. Our purpose was to determine differences in respiratory mechanics, inflammatory markers, and incidence of pulmonary embolism in patients with and without COVID-19 associated ARDS admitted in the same period and treated with a similar ventilation strategy.

Methods

A cohort study of COVID-19 associated ARDS and non COVID-19 patients in a Saudi Arabian center between June 1 and 15, 2020. We measured respiratory mechanics (ventilatory ratio (VR), recruitability index (RI), markers of inflammation, and computed tomography pulmonary angiograms.

Results

Forty-two patients with COVID-19 and 43 non-COVID patients with ARDS comprised the cohort. The incidence of “recruitable” patients using the recruitment/inflation ratio was slightly lower in COVID-19 patients (62 vs. 86%; p = 0.01). Fifteen COVID-19 ARDS patients (35.7%) developed a pulmonary embolism as compared to 4 (9.3%) in other ARDS patients (p = 0.003). In COVID-19 patients, a D-Dimer ≥ 5.0 mcg/ml had a 73% (95% CI 45–92%) sensitivity and 89% (95% CI 71–98%) specificity for predicting pulmonary embolism. Crude 60-day mortality was higher in COVID-19 patients (35 vs. 15%; p = 0.039) but three multivariate analysis showed that independent predictors of 60-day mortality included the ventilatory ratio (OR 3.67, 95% CI 1.61–8.35), PaO2/FIO2 ratio (OR 0.93; 95% CI 0.87–0.99), IL-6 (OR 1.02, 95% CI 1.00–1.03), and D-dimer (OR 7.26, 95% CI 1.11–47.30) but not COVID-19 infection.

Conclusion

COVID-19 patients were slightly less recruitable and had a higher incidence of pulmonary embolism than those with ARDS from other etiologies. A high D-dimer was predictive of pulmonary embolism in COVID-19 patients. COVID-19 infection was not an independent predictor of 60-day mortality in the presence of ARDS.

Conversion from dose-length product to effective dose in computed tomography venography of the lower extremities

For radiation dose assessment of computed tomography (CT), effective dose (ED) is often estimated by multiplying the dose-length product (DLP), provided automatically by the CT scanner, by a conversion factor. We investigated such conversion in CT venography of the lower extremities performed in conjunction with CT pulmonary angiography. The study subjects consisted of eight groups imaged using different scanners and different imaging conditions (five and three groups for the GE and Siemens scanners, respectively). Each group included ten men and ten women. The scan range was divided into four anatomical regions (trunk, proximal thigh, knee and distal leg), and DLP was calculated for each region (regional DLP). Regional DLP was multiplied by a conversion factor for the respective region, to convert it to ED. The sum of the ED values for the four regions was obtained as standard ED. Additionally, the sum of the four regional DLP values, an approximate of the scanner-derived DLP, was multiplied by the conversion factor for the trunk (0.015 mSv mGy cm^-1), as a simplified method to obtain ED. When using the simplified method, ED was overestimated by 32.3%-70.2% and 56.5%-66.2% for the GE and Siemens scanners, respectively. The degree of overestimation was positively and closely correlated with the contribution of the middle and distal portions of the lower extremities to total radiation exposure. ED/DLP averaged within each group, corresponding to the conversion factor, was 0.0089-0.0114 and 0.0091-0.0096 mSv mGy cm^-1for the GE and Siemens scanners, respectively. In CT venography of the lower extremities, ED is greatly overestimated by multiplying the scanner-derived DLP by the conversion factor for the trunk. The degree of overestimation varies widely depending on the imaging conditions. It is recommended to divide the scan range and calculate ED as a sum of regional ED values.

Therapeutic plasma exchange in patients with life-threatening COVID-19: a randomised controlled clinical trial

Assessment of efficacy of therapeutic plasma exchange (TPE) following life-threatening COVID-19. This was an open-label, randomised clinical trial of ICU patients with life-threatening COVID-19 (positive RT-qPCR plus ARDS, sepsis, organ failure, hyperinflammation). Study was terminated after 87/120 patients enrolled. Standard treatment plus TPE (n = 43) versus standard treatment (n = 44), and stratified by PaO2/FiO2 ratio (>150 vs. ≤150), were compared. Primary outcomes were 35-day mortality and TPE safety. Secondary outcomes were association between TPE and mortality, improvement in SOFA score, change in inflammatory biomarkers, days on mechanical ventilation (MV), and ICU length of stay (LOS). Eighty-seven patients [median age 49 (IQR 34-63) years; 82.8% male] were randomised (44 standard care; 43 standard care plus TPE). Days on MV (P = 0.007) and ICU LOS (P = 0.02) were lower in the TPE group. 35-Day mortality was non-significantly lower in the TPE group (20.9% vs. 34.1%; Kaplan-Meier, P = 0.582). TPE was associated with increased lymphocytes and ADAMTS-13 activity and decreased serum lactate, lactate dehydrogenase, ferritin, d-dimers and interleukin-6. Multivariable regression analysis provided several predictors of 35-day mortality: PaO2/FiO2 ratio (HR, 0.98, 95% CI 0.96-1.00; P = 0.02]; ADAMTS-13 activity (HR, 0.89, 95% CI 0.82-0.98; P = 0.01); pulmonary embolism (HR, 3.57, 95% CI 1.43-8.92; P = 0.007). Post-hoc analysis revealed a significant reduction in SOFA score for TPE patients (P < 0.05). In critically-ill COVID-19 patients, addition of TPE to standard ICU therapy was associated with faster clinical recovery and no increased 35-day mortality.

Ventilation/Perfusion Relationships and Gas Exchange: Measurement Approaches

Ventilation-perfusion ( V ˙ A / Q ˙ ) matching, the regional matching of the flow of fresh gas to flow of deoxygenated capillary blood, is the most important mechanism affecting the efficiency of pulmonary gas exchange. This article discusses the measurement of V ˙ A / Q ˙ matching with three broad classes of techniques: (i) those based in gas exchange, such as the multiple inert gas elimination technique (MIGET); (ii) those derived from imaging techniques such as single-photon emission computed tomography (SPECT), positron emission tomography (PET), magnetic resonance imaging (MRI), computed tomography (CT), and electrical impedance tomography (EIT); and (iii) fluorescent and radiolabeled microspheres. The focus is on the physiological basis of these techniques that provide quantitative information for research purposes rather than qualitative measurements that are used clinically. The fundamental equations of pulmonary gas exchange are first reviewed to lay the foundation for the gas exchange techniques and some of the imaging applications. The physiological considerations for each of the techniques along with advantages and disadvantages are briefly discussed. © 2020 American Physiological Society. Compr Physiol 10:1155-1205, 2020.

ESTIMATION OF RADIATION DOSE IN CT VENOGRAPHY OF THE LOWER EXTREMITIES: PHANTOM EXPERIMENTS USING DIFFERENT AUTOMATIC EXPOSURE CONTROL SETTINGS AND SCAN RANGES

We performed phantom experiments to assess radiation dose in computed tomography (CT) venography of the lower extremities. CT images of a whole-body phantom were acquired using different automatic exposure control settings and scan ranges, simulating CT venography. Tube current decreased in the lower extremities compared to the trunk. The scout direction and dose modulation strength affected tube current, dose length product (DLP) and effective dose. The middle and distal portions of the lower extremities contributed substantially to DLP but not to effective dose. When effective dose was estimated by multiplying DLP by a single conversion factor, overestimation was evident; this became more pronounced as the scan range narrowed. In CT venography of the lower extremities, the scout direction and modulation strength affect radiation dose. Use of DLP severely overestimates radiation dose and underestimates effects of scan range narrowing.

Prevalence and Risk Factors of Preoperative Deep Vein Thrombosis in Patients with End-Stage Knee Osteoarthritis

BACKGROUND

The purpose of this study is to determine the prevalence and the risk factors of DVT in end-stage OA patients.

METHODS

From March 2015 to June 2017, 521 patients with knee degenerative osteoarthritis undergoing knee arthroplasty were enrolled; 458 patients (87.9%) were admitted for primary total knee arthroplasty and 63 patients (12.1%) were admitted for unicompartmental knee arthroplasty. Parameters were compared using χ² or t-test for both the groups. Binary logistic regression analysis was used to determine risk factors.

RESULTS

The incidence of preoperative DVT was 6.7% (n = 35). Age in preoperative DVT group was significantly more than the non-DVT group (72.54 ± 6.53 vs. 68.65 ± 7.35, P = 0.002). Preoperative D-dimer >0.5 μg/mL (P < 0.001) was also associated with preoperative DVT in knee osteoarthritis patients. The incidence increased with age significantly (2.17% in <65 years, 6.86% in ≥65 <75 years, and 12.26% in ≥75 years) (P = 0.008). Thus, age (P = 0.041, OR 1.075, 95% CI [1.002-1.110]) and D-dimer >0.5 μg/mL (P < 0.001, OR 4.441, 95% CI [1.942-10.153]) were the independent risk factors for preoperative DVT in knee osteoarthritis patients.

CONCLUSIONS

The incidence of DVT in end-stage osteoarthritis was 6.7%. The results suggest that older people aged over 75 and D-dimer > 0.5 μg/mL were risk factors for DVT among patients admitted to the hospital for total knee arthroplasty. Instrumental screening should be encouraged, especially in subgroups at higher risk for preoperative DVT.

Dual-Energy Computed Tomography Pulmonary Angiography: Comparison of Vessel Enhancement between Linear Blended and Virtual Monoenergetic Reconstruction Techniques

INTRODUCTION

Optimal opacification of the pulmonary vasculature is a fundamental factor of a diagnostic quality computed tomography pulmonary angiogram (CTPA). This retrospective study examined the feasibility of utilising a noise-optimised monoenergetic reconstruction of the dual-energy computed tomography pulmonary angiogram (DE-CTPA) as an additional protocol to increase vessel opacification.

METHOD

The study involved a retrospective analysis of 129 patients, 69 males (average age 58 years), 60 females (average age 56 years) who underwent a DE-CTPA at a tertiary referral hospital. Linear blended 120 kilovoltage (kV) images (LB120) dual-energy (DE) data sets (50% 100 kV and 50% 140 kV) were compared to noise-optimised virtual monoenergetic image reconstruction (VMI+) at 40 kiloelectron volts (VMI+40). The attenuation of the pulmonary trunk measured in Hounsfield units (HU) between the equivalent axial slices of the LB120 data set and the VMI+40 data set underwent statistical analysis via a Wilcoxon paired-sample test.

RESULTS

VMI+40 (1161.500 HU) yielded a statistically significant increase in median attenuation within the pulmonary trunk compared to the LB120 (304.400 HU), with a median difference between monoenergetic reconstruction and standard dual energy of data sets of 827.5 HU (P < .001).

CONCLUSIONS

VMI+40 of the DE-CTPA scan demonstrates a statistically significant increase in vessel attenuation in all cases and may have utility in reducing the rates of indeterminate or repeated studies.

The Rate of Venous Thromboembolism Before and After Spine Surgery as Determined with Indirect Multidetector CT

BACKGROUND

This prospective cohort study investigated the rate of venous thromboembolism (VTE) before and after spine surgery as determined with use of indirect multidetector computed tomography (MDCT).

METHODS

We performed a prospective study of 105 patients (36 women and 69 men ranging in age from 38 to 88 years) undergoing spine surgery at 2 institutions. Indirect MDCT was performed before and 3 days after surgery. Patients with a history of dialysis or drug allergy to contrast medium were excluded.

RESULTS

No patient had symptomatic VTE preoperatively or postoperatively. The preoperative and postoperative rates of asymptomatic VTE were 4.8% and 13.0%, respectively; the rates of asymptomatic pulmonary embolism were 2.9% and 8.0%, respectively; and the rates of asymptomatic deep venous thrombosis were 3.8% and 6.0%, respectively. Age, sex, height, weight, body mass index, operative time, volume of intraoperative blood loss, and specific comorbidities (diabetes, hypertension, cardiac disease, previous VTE, and previous anticoagulation treatment) were not found to be risk factors.

CONCLUSIONS

Our findings demonstrated a low rate of preoperative VTE but a high rate of postoperative VTE in association with spine surgery. Surgeons need to be aware of the risk of VTE in patients undergoing spine surgery. MDCT is an effective and convenient technology for the early detection of VTE in such patients.

LEVEL OF EVIDENCE

Prognostic Level I. See Instructions for Authors for a complete description of levels of evidence.

D-dimer predicts pulmonary embolism after low-risk spine surgery

Introduction

Pulmonary embolism (PE) is a risk of mortality following spine surgery. Many studies have demonstrated that deep venous thrombosis (DVT) may affect and actually advance to PE, but few studies have shown how venous thromboembolism (VTE), including PE and DVT, affect blood markers after spine surgery. In this study, we examined changes in blood markers with PE or DVT after low-risk spine surgery, namely cervical laminoplasty or lumbar laminectomy.

Methods

Seventy-two spine surgery patients were studied. A 16-row multidetector computed tomography was performed before and 3 d after the surgery. Patients with a history of cerebral vascular accident or arterial thrombotic episode or pre-surgical asymptomatic PE or DVT were excluded. Plasma levels of soluble fibrin monomer complex, D-dimer, plasminogen activator inhibitor type-1 (PAI-1), and white blood cell and platelet counts were measured preoperatively and postoperatively at days 1, 3, and 7.

Results

No patient developed symptomatic post-surgical VTE. Six patients with asymptomatic PE and six with asymptomatic DVT were detected post-surgery, including one patient with both. D-dimer postoperatively at days 3 and 7 was significantly higher in the post-op PE group than in the no-PE group. PAI-1 preoperatively was significantly higher in the DVT and VTE groups than in the no-DVT and no-VTE groups.

Conclusions

Elevated D-dimer at postoperative days 3 and 7 is a predictive factor for the early diagnosis of PE after spine surgery. Moreover, elevated PAI-1 preoperatively is a predictive factor for the early diagnosis of DVT and VTE. Consequently, PE may occur through a pathway other than DVT.

Computed Tomography Angiographic Assessment of Acute Chest Pain

Acute chest pain is a leading cause of Emergency Department visits. Computed tomography angiography plays a vital diagnostic role in such cases, but there are several common challenges associated with the imaging of acute chest pain, which, if unrecognized, can lead to an inconclusive or incorrect diagnosis. These imaging challenges fall broadly into 3 categories: (1) image acquisition, (2) image interpretation (including physiological and pathologic mimics), and (3) result communication. The aims of this review are to describe and illustrate the most common challenges in the imaging of acute chest pain and to provide solutions that will facilitate accurate diagnosis of the causes of acute chest pain in the emergency setting.

Surgical Embolectomy for Acute Pulmonary Thromboembolism

Acute pulmonary thromboembolism is a catastrophic event, especially for hospitalized patients. The prognosis of pulmonary thromboembolism depends on the degree of pulmonary arterial occlusion. The mortality of massive pulmonary embolism is reportedly as high as 25% without cardiopulmonary arrest and 65% with cardiopulmonary arrest. In patients with unstable hemodynamics due to pulmonary thromboembolism, surgical pulmonary embolectomy is indicated for patients with a contraindication to thrombolysis, failed catheter therapy, or failed thrombolysis. Thrombolytic therapy adds an additional burden on patients who are at risk of potential hemorrhagic complications. It is also indicated if patients are already on a veno-arterial extra-corporate membrane oxygenator for circulatory collapse or cardiopulmonary arrest. The outcome for patients who require cardiopulmonary resuscitation for longer than 30 minutes is poor. Therefore, early triage for massive and sub-massive pulmonary embolism is crucial. A team approach including a cardiovascular surgeon may be effective to save critically ill patients. Prompt removal of emboli reduces the right ventricular load with quick recovery of cardiopulmonary function in the early postoperative period. A recent series reported excellent results, with in-hospital mortality of less than 10%. Surgical pulmonary embolectomy is an effective, safe, and easy procedure to save critical patients due to pulmonary thromboembolism.

Incidence of pulmonary emboli on chest computed tomography angiography based upon referral patterns

Pulmonary embolism (PE) is a potentially lethal condition, and the diagnosis of PE can be difficult. The purpose of this study is to evaluate the incidence of PE on chest computed tomography angiography (CTA) studies ordered in the inpatient, outpatient, and emergency department (ED) settings and further segregated based on the adult and pediatric populations, and by the ordering clinician (attending physicians, resident physicians, or physician extenders). A retrospective review of chest CTA examinations performed between July 1,2009 and June 30, 2010 was performed. Of 5848 adult CTA studies, PE was diagnosed in 594 (10.1 %). Of these positive studies, 315 (53 %) were inpatient, 234 (39.4 %) were ED patients, and 45 (7.6 %) were outpatient. Four hundred sixty-four of 4445 (10.4 %) CTA examinations ordered by attending physicians were positive for PE. Seventy-four of the 801 (9.2 %) CTA examinations ordered by resident physicians were positive for PE. Fifty-six of the 608 CTA examinations ordered by physician extenders were positive for PE. Thirty-three pediatric CTA studies for PE met criteria and none of them indicated PE. There is no significant difference in the incidence of PE in chest CTA based on setting or ordering clinician.

Pulmonary vascular diseases

Pulmonary vascular diseases encompass a large and diverse group of underlying pathologies ranging from venous thromboembolism to congenital malformations to inflammatory vasculitides. As a result, patients can present either acutely with dyspnea and chest pain or chronically with dyspnea on exertion, hypoxia, and right heart failure. Imaging, particularly with multidetector CT, plays a key role in the evaluation and management of patients with suspected pulmonary vascular disease and, given the widespread routine use of high-quality CT pulmonary angiography, it is imperative that radiologists be familiar these pathologies.

Treatment of single peripheral pulmonary emboli: patient outcomes and factors associated with decision to treat

BACKGROUND

Increasing use of computed tomography pulmonary angiography together with higher-resolution scanners has increased the detection of peripheral filling defects. Physicians face the dilemma of whether to treat patients with these findings, especially single defects. The aims of this study were to compare the outcomes of treated and untreated patients with single peripheral filling defects (SPFD) and identify factors associated with treatment.

METHODS

All cases with SPFDs over 66 months in a single institution were identified. Patient and treatment information were abstracted and data on 90-day mortality and postdischarge venous thromboembolism (VTE) were collected.

RESULTS

A total of 4906 computed tomography pulmonary angiograms were reviewed. A SPFD was identified in 3.1% (n = 153). Of the 153 patients, 134 met criteria for study inclusion. In 99 of 134 (73.9%) studies, the defect was called a pulmonary embolus (PE) by the initial radiologist. Treatment was administered to 61 of 134 (45.5%) patients; 5 patients died in each group. Postdischarge VTE occurred in 3 treated and 2 untreated patients. In 52 of 153 cases, an additional study was performed. None of the patients with normal ventilation perfusion scan and compression ultrasound received treatment. Immobility (odds ratio [OR]: 3.90, 95% confidence interval [CI]: 1.45-10.60), previous VTE (OR: 3.72, 95% CI: 1.18-11.70), and determination of PE by the radiologist (OR: 24.68, 95% CI: 5.40-112.90) were associated with treatment.

CONCLUSIONS

There was no difference in 90-day mortality or recurrence between treated and untreated patients. The most influential factor associated with treatment was the radiologist's interpretation. When secondary lung imaging studies were negative, no patient received treatment.

The incidence of venous thromboembolism before and after total knee arthroplasty using 16-row multidetector computed tomography

We performed a prospective study to determine the incidence of venous thromboembolism (VTE) using 16-row multidetector computed tomography (MDCT). The study included 71 patients who underwent total knee arthroplasty between September 2004 and March 2009. Multidetector computed tomography was performed 4 days before and after surgery. No patient had any presurgical symptoms of VTE. Presurgical and postsurgical incidences of pulmonary thromboembolism plus deep vein thrombosis were 0% and 13%, respectively; pulmonary thromboembolism alone, 1% and 3%, respectively; and deep vein thrombosis alone, 8% and 34%, respectively. Because asymptomatic VTE was noted in 9% of patients before surgery and 51% after surgery, we conclude that performing MDCT before and after total knee arthroplasty may be useful to clarify the incidence of VTE and to develop appropriate strategies for treatment and prevention.

Multimodality imaging of the peripheral venous system

The purpose of this article is to review the spectrum of image-based diagnostic tools used in the investigation of suspected deep vein thrombosis (DVT). Summary of the experience gained by the author as well as relevant publications, regarding vein imaging modalities taken from a computerized database, was reviewed. The imaging modalities reviewed include phlebography, color Doppler duplex ultrasonography (CDDUS), computerized tomography angiography (CTA) and venography (CTV), magnetic resonance venography (MRV), and radionuclide venography (RNV). CDDUS is recommended as the modality of choice for the diagnosis of DVT. A strategy combining clinical score and D-dimer test refines the selection of patients. Phlebography is reserved for discrepant noninvasive studies.

The validity of hyperdense lumen sign in non-contrast chest CT scans in the detection of pulmonary thromboembolism

It is possible to identify high-attenuation clots in pulmonary thromboembolism using non-contrast computed tomography (CT) of the chest. Such detection may be crucial for timely initiation of appropriate therapy. This study was undertaken to determine the validity of the hyperdense lumen (high-attenuation clot) sign in unenhanced chest CT in detecting pulmonary thromboembolism. Non-contrast and contrast-enhanced CT images of the chest of 121 patients who had undergone standard CT pulmonary angiography (pulmonary CTA) were reviewed separately. The absence or presence of luminal hyperdensities within the pulmonary arteries in the non-contrast images was determined. The average CT attenuation differences between the high attenuation clots and pulmonary arteries were computed. Findings in the non-contrast images were correlated with the contrast-enhanced images. Twenty-five patients were positive for pulmonary thromboembolism in the pulmonary CTAs. Of these 25 patients, nine were positive for the hyperdense lumen sign in the non-contrast CT images. The hyperdense lumen sign has an over-all sensitivity of 36.0%, specificity of 99.0%, PPV of 90.0%, and NPV of 85.6% (κ=0.449; P-value<0.001). In detecting central thromboembolism, the sensitivity, specificity, PPV, and NPV of this sign were 66.7, 99.1, 88.9, and 96.4%, respectively (κ=0.740; P-value<0.001). The sign was less sensitive in peripheral thromboembolism (κ=0.358; P-value<0.001). The mean (±SD) attenuation difference between the clot and pulmonary blood pool was 22.76 (±4.20) HU (P-value<0.001). The hyperdense lumen sign is a useful indicator of acute pulmonary thromboembolism in non-contrast chest CT scans particularly in cases involving the central pulmonary arteries.

Prospective respiratory-triggered 64-slice CT pulmonary angiography for detection of pulmonary embolism--a feasibility study in a porcine model

The objective of this study is to investigate the feasibility of prospectively respiratory-triggered CT pulmonary angiography (CTPA) for detection of pulmonary embolism (PE) in a porcine model. A free-breathing respiratory-triggered multislice CTPA (120 kV, 140 mAs(eff), 2.5-mm slice thickness) and two CTPA in breath-hold technique (120 kV, 140 mAs(eff.) and 250mAs(eff), 1-mm and 3-mm image reconstruction) were performed in six pigs with pulmonary embolism. Diagnostic accuracy was computed, and differences in detection rates between both techniques were assessed on a per-embolus basis with the Wilcoxon test. Thin-sliced 1-mm images, acquired with 250mAs(eff), served as the standard of reference. Respiratory-triggered CTPA reached high diagnostic accuracy in detection of lobar and segmental PE equal to the results with the breath-hold technique (p > 0.05). For detection of subsegmental emboli, standard breath-hold techniques performed significantly better than respiratory-gated CTPA (sensitivity, 68.3% versus 24.4%; p < 0.05). Free-breathing respiratory-triggered CTPA is feasible for detection of lobar and segmental PE, with diagnostic accuracy equivalent to that of a standard CTPA in breath-hold. Although this technique is not recommended for assessment of emboli in the subsegmental vasculature, prospective respiratory-triggered CTPA may be of added value in patients who cannot hold their breath appropriately for CTPA scanning.

Thoracic causes of acute abdominal pain

The origin of abdominal pain may be extra-abdominal, caused by a thoracic illness. This article illustrates the various thoracic disorders that may present with acute abdominal pain. An erroneous focus on the abdomen alone can easily lead to misdiagnosis and incorrect treatment. In cases of unexplained acute abdominal pain, radiologists should be aware of also viewing beyond the borders of the abdomen. The key to most of these thoracic diagnoses is detection of pulmonary consolidation, pleural fluid or pericardial fluid.

The interobserver agreement between residents and experienced radiologists for detecting pulmonary embolism and DVT with using CT pulmonary angiography and indirect CT venography

Objective

We wanted to prospectively evaluate the interobserver agreement between radiology residents and expert radiologists for interpreting CT images for making the diagnosis of pulmonary embolism (PE).

Materials and Methods

We assessed 112 consecutive patients, from April 2007 to August 2007, who were referred for combined CT pulmonary angiography and indirect CT venography for clinically suspected acute PE. CT scanning was performed with a 64×0.5 collimation multi-detector CT scanner. The CT studies were initially interpreted by the radiology residents alone and then the CT images were subsequently interpreted by a consensus of the resident plus an experienced general radiologist and an experienced chest radiologist.

Results

Two of the 112 CTs were unable to be interpreted (1.7%). Pulmonary artery clots were seen on 36 of the thoracic CT angiographies (32%). The interobserver agreement between the radiology residents and the consensus interpretation was good (a kappa index of 0.73). All of the disagreements (15 cases) were instances of overcall by the resident on the initial interpretation. Deep venous thrombosis was detected in 72% (26 of 36) of the patients who had PE seen on thoracic CT. The initial and consensus interpretations of the CT venography images disagreed for two cases (kappa statistic: 0.96).

Conclusion

It does not seem adequate to base the final long-term treatment of PE on only the resident's reading, as false positives occurred in 13% of such cases. Timely interpretation of the CT pulmonary angiography and CT venography images should be performed by experienced radiologists for the patients with suspected PE.

Performance of the Wells and Revised Geneva scores for predicting pulmonary embolism

OBJECTIVE

The objective of the study was to compare two scoring methods to predict the risk of pulmonary embolism (PE) as diagnosed with computed tomography angiography (CTA) and/or CT venography (CTV).

METHODS

Prospectively over a 8-month period, emergency department patients and hospital inpatients with suspected PE were consecutively examined and their Wells and Revised Geneva scores calculated to stratify them into a risk group for PE probability. Then all patients were examined with CTA and CTV to determine the presence or absence of PE, as diagnosed by experienced radiology staff physicians.

RESULTS

During the study period, 167 patients were suspected of having a PE and were interviewed for the calculation of their Wells and Revised Geneva scores. All patients underwent CTA or CTV, but the images of only 148 patients were adequate enough to make a certain diagnosis regarding PE. The data of these 148 patients were used for the study. The rates of PE in high, moderate, and low PE risk groups determined according to the Wells score and the Revised Geneva score were 89.6, 26.4, 7.8 and 83.3, 25.6, 0%, respectively. Among both inpatients and ED patients the area under the Wells score receiver operating characteristic curve was higher (P=0.04). When data from only ED patients were analyzed (104 patients) the scoring systems was not significantly different (P=0.07).

CONCLUSION

The Wells rule seems to be more accurate among both inpatients and emergency department patients. The Revised Geneva score can be used in emergency department patients with high reliability.

The role of multidetector computed tomography angiography for the diagnosis of pulmonary embolism

From a radiological point of view, computed tomography pulmonary angiography (CTPA) has effectively become the de-facto first-line imaging test for the evaluation of pulmonary embolism (PE), as patients with a high-quality negative CTPA do not require further examination or treatment for suspected PE. We are likely to see further technical developments in CT technology in the near future. These advances will most likely further improve image quality. Several questions or issues remain, including strategies for further imaging when CT is inconclusive or contraindicated, issues regarding radiation exposure, the prevalence of PE in specific populations, best tests and pathways in specific patient groups, including patients with specific comorbidities such as oncology patients or patients with chronic obstructive pulmonary disease. Also, the question whether all PE patients need anticoagulation, the clinical effect of follow-up imaging, and the accuracy of different clinical prediction rules, remains.

ASMBS guideline on the prevention and detection of gastrointestinal leak after gastric bypass including the role of imaging and surgical exploration

The following position statement is issued by the American Society for Metabolic and Bariatric Surgery in response to numerous inquiries made to the Society by patients, physicians, society members, hospitals, health insurance payors, the media, and others, regarding the complication of gastrointestinal leak after gastrointestinal bariatric procedures. In this statement, available data regarding leak are summarized and suggestions made regarding reasonable approaches to the prevention and postoperative detection based on current knowledge, expert opinion, and published peer-reviewed scientific evidence available at this time. The intent of issuing such a statement is to provide objective information about the complication of leak. The statement is not intended as, and should not be construed as, stating or establishing a local, regional, or national standard of care. The statement will be revised in the future as additional evidence becomes available.

Evaluation of pulmonary embolism in a pediatric population with high clinical suspicion

BACKGROUND

Pulmonary embolism (PE) is an underdiagnosed entity in the pediatric population in part because of the low level of suspicion and awareness in the clinical world.

OBJECTIVE

To examine its relative prevalence, associated risk factors and imaging features in our pediatric population.

MATERIALS AND METHODS

A total of 92 patients age 21 years and younger with a high clinical suspicion of PE and who had available radiographic studies were identified from January 2003 to September 2006. Patients with a positive CT scan or a high probability ventilation/perfusion scan formed the case group; patients with a high clinical suspicion of PE and no radiographic evidence of PE or deep venous thrombosis (DVT), randomly matched in age and sex, became the matched control group. We reviewed the charts of both groups and analyzed the imaging studies.

RESULTS

In our hospital, the prevalence of PE in patients with a strong suspicion of PE was 14%. The overall prevalence of thromboembolic disease (PE and/or DVT) was 25%. Recent surgery or orthopedic procedure, blood dyscrasias and contraceptive use were more common in patients with PE. No child died of PE in our study. The youngest child with PE in our study was 13 years. Girls were twice as likely to develop PE as boys.

CONCLUSION

PE is a relatively common diagnosis in our tertiary care pediatric population when the clinical suspicion is high. We suggest increased awareness and index of suspicion in order to initiate prompt diagnostic imaging and treatment.

MDCT of 220 consecutive patients with suspected acute pulmonary embolism: incidence of pulmonary embolism and of other acute or non-acute thoracic findings

PURPOSE

This study was undertaken to evaluate the incidence of pulmonary embolism (PE) and other clinically relevant thoracic findings discovered on contrast-enhanced multidetector computed tomography (MDCT) examination in patients with a suspicion of acute PE.

MATERIALS AND METHODS

We retrospectively reviewed 220 reports of 40-row MDCT exams in consecutive patients (101 men, 119 women; mean age 55 years+/-18) suspected for acute PE. Presenting symptoms and risk factors were recorded. Image quality and incidence of PE and other clinically relevant thoracic findings were evaluated.

RESULTS

MDCT were diagnostic in 96.8% of patients. Nineteen patients (8.6%) were positive for PE. Signs and symptoms were present in 82.7% (182) and risk factors in 38.2% (84) of the population. Clinically relevant thoracic findings were detected in 45.9% (101) of the patients. Ten patients had PE and other thoracic findings. Half of the patients (110) had neither PE nor other clinically relevant thoracic findings.

CONCLUSIONS

Chest MDCT, with an excellent overall image quality, provided an explanation for the clinical presentation in about 50% of emergency department patients studied and was useful in detecting PE and other thoracic diseases with symptoms mimicking PE. However, half of the exams were negative.

CT angiography in suspected pulmonary embolism: impact of patient characteristics and different venous lines on vessel enhancement and image quality

OBJECTIVE

The objective of our study was to compare image quality, patient characteristics, and different catheters in pulmonary CT angiography (CTA) performed with bolus tracking and z-axis automated tube current modulation (ATCM) in patients with suspected pulmonary embolism.

SUBJECTS AND METHODS

One hundred twenty-six patients were referred to undergo pulmonary CTA with bolus tracking and ATCM. Besides patient characteristics, the type, position, size, and side of venous catheters were documented. Pulmonary vessel enhancement and image noise were quantified; signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Subjective vessel contrast was assessed by two radiologists in consensus.

RESULTS

Patient age showed a moderate but significant positive correlation to vessel enhancement (r = 0.244, p = 0.006), CNR (r = 0.178, p = 0.046), and subjective image quality (r = 0.344, p < 0.001). Patient weight revealed a significant negative correlation to vessel enhancement (r = -0.496, p < 0.001), SNR (r = -0.446, p < 0.001), CNR (r = -0.425, p < 0.001), and subjective image quality (r = -0.422, p < 0.001). In univariate analysis, SNR and CNR were significantly higher in patients who received contrast medium through peripheral catheters (30 +/- 13 and 27 +/- 13, respectively) than in those in whom central catheters were used (22 +/- 8 and 19 +/- 7, p = 0.041 and p = 0.029, respectively). Neither patient sex nor catheter size, position, or side had any significant impact on image quality.

CONCLUSION

Patient age and weight showed significant impact on vascular attenuation and image quality in pulmonary CTA with bolus tracking and ATCM, whereas patient sex and different peripheral catheters did not significantly influence image parameters.

[Indirect CT venography in patients with clinical suspicion of pulmonary thromboembolism: our experience and possible indications for the test]

OBJECTIVE

Our objective was to evaluate the sensitivity of indirect computed tomography (CT) venography in the evaluation of deep vein thrombosis and to establish possible general indications for this technique in cases with clinical suspicion of thromboembolic disease.

MATERIAL AND METHODS

We studied 76 patients with clinical suspicion of pulmonary thromboembolism who underwent CT angiography of the pulmonary arteries and indirect CT venography. We correlated the results with those of ultrasound examination of the limbs in 63 cases to determine the sensitivity of the test. We analyzed the cases in which the findings at indirect CT venography changed the management of the patient.

RESULTS

The concordance between indirect CT venography and ultrasound was 92%. Thromboembolic disease was diagnosed in 40% of the cases. In these cases, CT angiography of the pulmonary arteries was positive in 80% and in the remaining 20% only CT venography was positive. In two cases, abdominal pathology that changed the clinical management of the patients was found.

CONCLUSIONS

Indirect CT venography is sensitive in the detection of deep vein thrombosis in patients with clinical suspicion of pulmonary thromboembolism. This technique can shorten the time to diagnosis, increase diagnostic precision, and provide additional clinical data that may be important in the patient's management. However, its generalized use is limited because it involves the use of ionizing radiation.