Subsequent pulmonary embolism: risk after a negative helical CT pulmonary angiogram--prospective comparison with scintigraphy

A Novel Computed Tomography Image Reconstruction for Improving Visualization of Pulmonary Vasculature: Comparison Between Preprocessing and Postprocessing Images Using a Contrast Enhancement Boost Technique

OBJECTIVE

This study aimed to evaluate chest computed tomography (CT) angiography image quality using the contrast enhancement (CE)-boost technique compared with conventional images.

METHODS

Forty patients who underwent contrast-enhanced chest CT were included. Combined CT angiography images of the iodinated image obtained from the subtraction of nonenhanced CT images and CT angiography images were used to generate CE-boost images. Computed tomography attenuation, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) for the right and left pulmonary arteries as the central and subsegmental arteries as peripheral vessels were assessed. Subjective image quality was rated on a 5-point scale by 2 radiologists. Image quality was assessed using a paired t test.

RESULTS

Computed tomography attenuation in the main pulmonary artery was significantly higher for the CE-boost images (311.05 ± 91.94) than for the conventional images (221.25 ± 61.21, P < 0.001). Similarly, the CE-boost images resulted in significantly higher CT attenuation in the subsegmental arteries (right, 305.34 ± 90.13; left, 313.05 ± 97.21) than in the conventional images (right, 218.45 ± 63.16; left, 223.89 ± 74.27). The CE-boost technique demonstrated marked improvement in the visualization of the peripheral pulmonary artery without the administration of a higher iodine delivery rate. The mean SNR and CNR were also significantly higher in the central and peripheral vessels in the CE-boost images than in the conventional images (P < 0.001). In the subjective analysis, the image contrast and vascular contrast edge were significantly higher for the CE-boost images than for conventional images (P < 0.001).

CONCLUSIONS

The CE-boost technique increases not only the visualization of peripheral arteries by improving vascular attenuation but also the SNR and CNR.

Screening for Pulmonary Embolism with a D-Dimer Assay: Do we Still Need to Assess Clinical Probability as Well?

Clinical risk stratification and D-dimer assay can be of use in excluding pulmonary embolism in patients presenting to emergency departments but many D-dimer assays exist and their accuracy varies. We used clinical risk stratification combined with a quantitative latex-agglutination D-dimer assay to screen patients before arranging further imaging if required. Retrospective analysis of a sequential series of 376 patients revealed that no patient with a D-dimer of <275 ng/mL was diagnosed with pulmonary embolism, irrespective of clinical probability. We conclude that a latex-agglutination assay could be used to exclude pulmonary embolism without the necessity for clinical risk stratification. If these findings are borne out by further work, D-dimer strategies to exclude pulmonary embolism could substantially reduce imaging workload.

Risk of pulmonary embolism after a prior negative CT pulmonary angiogram

CONTEXT

With increasing utilization of computed tomography pulmonary angiography (CTPA) for the diagnosis of pulmonary embolism (PE), many patients undergo repeat CTs.

OBJECTIVE

The aim of this study is to identify the rate of positive subsequent CTPAs after an initial negative CTPA and whether there is a risk-free period after a negative CTPA.

METHODS

We evaluated 318 patients with at least 1 subsequent CTPA after an initial negative CTPA, with 786 total CTPAs. We also evaluated a control group of 200 unselected CTPAs.

RESULTS

The positive rate in the repeat group was 7% at the first repeat CTPA and 10% per-patient within 1000 days. The positive rate in the control group was 9% (P= not significant). No risk-free period was seen, with a positive rate of 5% within 2 weeks after a negative CTPA. The number of prior negative CTPAs showed a trend towards decreasing rate of the subsequent CTPA being positive, but this did not meet statistical significance.

DISCUSSION

There is no risk-free period after an initial negative CTPA, and therefore, patients with clinical suspicion of PE should be rescanned even after a recent negative study. Even patients with multiple negative prior CTPAs have a measurable risk of subsequent PE. Established clinical prediction scoring systems must be used to triage the patients who need CTPAs.

Radiology in the Intensive Care Unit (Part 2)

This review of intensive care unit (ICU) radiology has been divided into two sections. In Part 1, previously published, the discussion focused on the role of the portable radiograph in the evaluation of the critically ill patient and the impact of the introduction of digital radiography and picture-archiving communications systems on patient care. Part 2 of this review will emphasize the role of computed tomography and the increasing contribution of image-guided interventional procedures in patient management. The deleterious effects of mechanical ventilation due to barotrauma will also be discussed.

Radiopharmaceutical Options for the Ventilation Part of Ventilation-Perfusion Scintigraphy Performed for the Indication of Pulmonary Embolism: US Practice Survey

PURPOSE

This US survey aimed to determine (1) relative utilization of the 2 techniques, a gas radiopharmaceutical technique (GRT) versus aerosolized radiopharmaceutical technique (ART), in ventilation-perfusion scintigraphy done for pulmonary embolism indication and (2) radiopharmaceuticals (RFs) used.

PATIENTS AND METHODS

Nuclear medicine physicians and technologists were sent a questionnaire asking which RF(s) their imaging facilities are using for ventilation imaging. Respondents were classified as reporting from academic/teaching facilities (ATFs) or from community-based facilities (CBFs).

RESULTS

Of the 256 surveyed, 78 responded (30.5%), who reported about 158 facilities. Majority (90/158, 57%) were CBFs, whereas the rest (68/158, 43%) were ATFs. Overall, slight majority (92/158, 58%) used ART, 90 using (99m)Tc-DTPA, one using (99m)Tc-sulfur colloid (SC), and one using (99m)Tc-PYP. Minority (66/158, 42%) used GRT (all ¹³³Xe). In the CBFs, a slight majority (55/90, 61%) used ART (including one that used (99m)Tc-PYP), whereas the rest 35 (39%) of 90 used GRT. In the ATFs, a slight majority (37/68, 54.4%) used ART (including 1 facility that used (99m)Tc-SC), whereas the rest (31/68, 45.6%) used GRT. There was no statistically significant difference in ART:GRT ratios between CBFs and ATFs (P = 0.35).

CONCLUSIONS

Aerosolized RF technique is overall more common (57%) than GRT, about the same at CBFs and at ATFs, and almost all ART using (99m)Tc-DTPA. Therefore, (99m)Tc-DTPA price increase would have impacted a significant number of the US facilities, which should increase interest in alternatives identified by this survey—(99m)Tc-SC and (99m)Tc-PYP.

Contrast enhanced pulmonary magnetic resonance angiography for pulmonary embolism: Building a successful program

The performance of contrast enhanced pulmonary magnetic resonance angiography (MRA) for the diagnosis of pulmonary embolism (PE) is an effective non-ionizing alternative to contrast enhanced computed tomography and nuclear medicine ventilation/perfusion scanning. However, the technical success of these exams is very dependent on careful attention to the details of the MRA acquisition protocol and requires reader familiarity with MRI and its artifacts. Most practicing radiologists are very comfortable with the performance and interpretation of computed tomographic angiography (CTA) performed to detect pulmonary embolism but not all are as comfortable with the use of MRA in this setting. The purpose of this review is to provide the general radiologist with the tools necessary to build a successful pulmonary embolism MRA program. This review will cover in detail image acquisition, image interpretation, and some key elements of outreach that help to frame the role of MRA to consulting clinicians and hospital administrators. It is our aim that this resource will help build successful clinical pulmonary embolism MRA programs that are well received by patients and physicians, reduce the burden of medical imaging radiation, and maintain good patient outcomes.

The value of CTPA for diagnosing acute pulmonary thromboembolism and the ensuing right ventricular dysfunction

The value of computed tomography pulmonary angiography (CTPA) for the diagnosis of right ventricular dysfunction (RVD) subsequent to acute pulmonary embolism (PE). The ultrasonic cardiography (UCG) was used to assess RVD, one of the diagnostic criteria of PE caused hemodynamic collapse. Seventy six patients with confirmed PE were divided into massive (52 cases) and non-massive PE group (24 cases). The diagnostic criteria assessed for the imminent RVD were: (1) the ratio of axial diameters of the right and left ventricular chambers (RVd/LVd) exceeding 1, or (2) the right ventricular end-diastolic diameter measuring >30 mm. The CTPA diagnosed RVD was positive in 36 and negative in 40 cases. The RVD assessed by UCG was positive in 31 and negative in 45 cases. In comparison to UCG, the CTPA results UCG exhibited 96.77 % sensitivity 96.77 % and 86.67 specificity. The evaluated values both of these techniques were found in good agreement by the kappa value (κ) of 0.81, P < 0.001. In 52 cases of massive PE, CTPA determined RVD was positive in 34, and negative in 18 cases. In comparison, UCG diagnosed RVD was positive in 31 and negative in 21 cases. The sensitivity and specificity of CTPA results compared to those of UCG were 91.18 and 85.71 %, respectively. The estimates obtained were in good agreement as indicated by 0.88 κ value and P < 0.001. Twenty four cases of non-massive PE were RVD negative when assessed by CTPA, UCG however showed two cases positive in this group. Compared to UCG, the specificity of CTPA in evaluating RVD was 100 %. In the massive PE group, the average estimate of RVd/LVd ratio was significantly higher than 1 as analyzed by the non-parametric Mann-Whitney test (P < 0.001). The CTPA and UCG results showed a good correlation in massive PE cases. However, in non-massive PE group, results from two techniques were not correlated. The CTPA can accurately and reliably diagnose the PE and ensuing by estimating changes in the anatomical parameters of right ventricle. Hence, it can allow prompt diagnosis and an appropriate treatment leading to an improved prognosis.

70 kVp computed tomography pulmonary angiography: potential for reduction of iodine load and radiation dose

PURPOSE

The purpose of the study was to evaluate 70 kVp dual-source computed tomography pulmonary angiography (CTPA) with reduced iodine load in comparison with single-source 70 and 100 kVp CTPA with standard iodine load regarding image quality and radiation dose.

MATERIALS AND METHODS

Three groups with 40 consecutive patients each underwent either standard single-source 100 kVp (120 mAs; group A), single-source 70 kVp (208 mAs; group B), or dual-source 70 kVp CTPA (416 mAs; group C). A volume of 70 mL of contrast material with 400 mg I/mL (groups A, B) or 300 mg I/mL (group C) was administered. Chest diameter, dose-length product, intravascular signal attenuation, image noise, signal to noise ratio (SNR), and contrast to noise ratio (CNR) were compared. Two observers rated subjective image quality regarding intravascular enhancement and image noise using 5-point scales.

RESULTS

Chest diameter and age were similar (P ≥ 0.28) for all groups. Compared with group A, the average dose-length product was 59% lower in group B (67.3 ± 11.8 vs. 164.7 ± 50.6 mGy cm, P<0.001) and similar between groups A and C (167.7 ± 41.2 mGy cm, P = 0.39). Average SNR and CNR were significantly higher for group C (21.5 ± 4.7 and 19.0 ± 4.5, respectively) compared with groups A (18.3 ± 3.5 and 15.8 ± 3.4, respectively) and B (17.3 ± 5.8 and 15.6 ± 5.5, respectively; all Ps ≤ 0.001). Subjective image quality ratings regarding enhancement and noise were highest for group C (1.73 ± 0.62 and 2.03 ± 0.66, respectively).

CONCLUSIONS

Compared with standard 100 kVp CTPA, single-source 70 kVp CTPA allows for significant radiation dose savings with comparable SNR and CNR, whereas dual-source 70 kVp CTPA results in a superior objective image quality albeit a reduction of iodine concentration.

Computed tomography: revolutionizing the practice of medicine for 40 years

Computed tomography (CT) has had a profound effect on the practice of medicine. Both the spectrum of clinical applications and the role that CT has played in enhancing the depth of our understanding of disease have been profound. Although almost 90 000 articles on CT have been published in peer-reviewed journals over the past 40 years, fewer than 5% of these have been published in Radiology. Nevertheless, these almost 4000 articles have provided a basis for many important medical advances. By enabling a deepened understanding of anatomy, physiology, and pathology, CT has facilitated key advances in the detection and management of disease. This article celebrates this breadth of scientific discovery and development by examining the impact that CT has had on the diagnosis, characterization, and management of a sampling of major health challenges, including stroke, vascular diseases, cancer, trauma, acute abdominal pain, and diffuse lung diseases, as related to key technical advances in CT and manifested in Radiology.

Imaging diagnosis of acute pulmonary embolism

Pulmonary embolism represents a major public healthcare problem and it also imposes frequent clinical diagnostic issues. Despite the availability of the D-dimer tests, imaging remains the mainstay for its diagnosis. Computed tomography pulmonary angiography (CTPA) is now the most widely used diagnostic test and its utility has been well validated in a large number of trials. Nuclear medicine techniques, which are also well established, are now used significantly less frequently. Magnetic resonance pulmonary angiography is developing as an alternative to CTPA in patients who have contraindications to iodinated contrast media. Catheter pulmonary angiography remains the gold standard, although it is being used increasingly less frequently. In this article, we review the current knowledge on the imaging diagnosis of acute pulmonary embolism with special emphasis on the noninvasive techniques.

Magnetic resonance and computed tomography imaging of the structural and functional changes of pulmonary arterial hypertension

The current Dana Point Classification system (2009) distinguishes elevation of pulmonary arterial pressure into pulmonary arterial hypertension (PAH) and pulmonary hypertension. Fortunately, PAH is not a common disease. However, with the aging of the First World's population, heart failure has become an important outcome of pulmonary hypertension, with up to 9% of the population involved. PAH is usually asymptomatic until late in the disease process. Although features that are indirectly related to PAH are found on noninvasive imaging studies, its diagnosis and management still require right heart catheterization. Imaging features of PAH include the following: (1) enlargement of the pulmonary trunk and main pulmonary arteries; (2) decreased pulmonary arterial compliance; (3) tapering of the peripheral pulmonary arteries; (4) enlargement of the inferior vena cava; and (5) increased mean transit time. The chronic requirement to generate high pulmonary arterial pressure measurably affects the right heart and main pulmonary artery. This change in physiology causes the following structural and functional alterations that have been shown to have prognostic significance: relative area change (RAC) of the pulmonary trunk, right ventricular stroke volume index, right ventricular stroke volume, right ventricular end-diastolic volume index, left ventricular end-diastolic volume index, and baseline right ventricular ejection fraction <35%. All of these variables can be quantified noninvasively and followed up longitudinally in each patient using magnetic resonance imaging to modify the treatment regimen. Untreated PAH frequently results in rapid clinical decline and death within 3 years of diagnosis. Unfortunately, even with treatment, fewer than half of these patients are alive at 4 years.

Effectiveness of MR angiography for the primary diagnosis of acute pulmonary embolism: clinical outcomes at 3 months and 1 year

PURPOSE

To determine the effectiveness of MR angiography for pulmonary embolism (MRA-PE) in symptomatic patients.

MATERIALS AND METHODS

We retrospectively reviewed all patients whom were evaluated for possible pulmonary embolism (PE) using MRA-PE. A 3-month and 1-year from MRA-PE electronic medical record (EMR) review was performed. Evidence for venous thromboembolism (VTE) (or death from PE) within the year of follow-up was the outcome surrogate for this study.

RESULTS

There were 190 MRA-PE exams performed with 97.4% (185/190) of diagnostic quality. There were 148 patients (120 F: 28 M) that had both a diagnostic MRA-PE exam and 1 complete year of EMR follow-up. There were 167 patients (137 F: 30 M) with 3 months or greater follow-up. We found 83% (139/167) and 81% (120/148) MRA-PE exams negative for PE at 3 months and 1 year, respectively. Positive exams for PE were seen in 14% (23/167). During the 1-year follow-up period, five patients (false negative) were diagnosed with DVT (5/148 = 3.4 %), and one of these patients also experienced a non-life-threatening PE. The negative predictive value (NPV) for MRA-PE was 97% (92-99; 95% CI) at 3 months and 96% (90-98; 95% CI) with 1 year of follow-up.

CONCLUSION

The NPV of MRA-PE, when used for the primary diagnosis of pulmonary embolism in symptomatic patients, were found to be similar to the published values for CTA-PE. In addition, the technical success rate and safety of MRA-PE were excellent.

Cement pulmonary embolism after vertebroplasty

In recent years, the use of vertebral cementing techniques for vertebroplasty and kyphoplasty has spread for the treatment of pain associated with osteoporotic vertebral compression fractures. This is also associated with the increased incidence of complications related with these procedures, the most frequent being originated by leakage of cementation material. Cement can escape into the vertebral venous system and reach the pulmonary circulation through the azygous system and cava vein, producing a cement embolism. This is a frequent complication, occurring in up to 26% of patients undergoing vertebroplasty but, since most patients have no clinical or hemodynamical repercussion, this event usually goes unnoticed. However, some serious, and even fatal cases, have been reported. We report the case of a 74-year-old male patient who underwent vertebroplasty for persistent pain associated with osteoporotic L3 vertebral fracture and who developed a cement leak into the cava vein and right pulmonary artery during the procedure. Although he developed a pulmonary cement embolism, the patient remained asymptomatic and did not present complications during follow-up.

Pulmonary embolism

Pulmonary embolism (PE) remains one of the most challenging medical diseases in the emergency department. PE is a potentially life threatening diagnosis that is seen in patients with chest pain and/or dyspnea but can span the clinical spectrum of medical presentations. In addition, it does not have any particular clinical feature, laboratory test, or diagnostic modality that can independently and confidently exclude its possibility. This article offers a review of PE in the emergency department. It emphasizes the appropriate determination of pretest probability, the approach to diagnosis and management, and special considerations related to pregnancy and radiation exposure.

Critical issues in the evaluation and management of adult patients presenting to the emergency department with suspected pulmonary embolism

This clinical policy from the American College of Emergency Physicians is the revision of a 2003 clinical policy on the evaluation and management of adult patients presenting with suspected pulmonary embolism (PE).(1) A writing subcommittee reviewed the literature to derive evidence-based recommendations to help clinicians answer the following critical questions: (1) Do objective criteria provide improved risk stratification over gestalt clinical assessment in the evaluation of patients with possible PE? (2) What is the utility of the Pulmonary Embolism Rule-out Criteria (PERC) in the evaluation of patients with suspected PE? (3)What is the role of quantitative D-dimer testing in the exclusion of PE? (4) What is the role of computed tomography pulmonary angiogram of the chest as the sole diagnostic test in the exclusion of PE? (5) What is the role of venous imaging in the evaluation of patients with suspected PE? (6) What are the indications for thrombolytic therapy in patients with PE? Evidence was graded and recommendations were given based on the strength of the available data in the medical literature.

The role of imaging techniques in the assessment of pulmonary circulation

Knowledge of the structure and function of pulmonary circulation has evolved considerably in the last few decades. The use of non-invasive imaging techniques to assess the anatomy and function of the pulmonary vessels and heart has taken on added importance with the recent advent of novel therapies. Imaging findings not only constitute a diagnostic tool but have also proven to be essential for prognosis and treatment follow-up. This article reviews the myriad of imaging methods currently available for the assessment of pulmonary circulation, from the simple chest X-ray to techniques that are more complex and promising, such as electrical impedance tomography.

The value of 64-detector row computed tomography for the exclusion of pulmonary embolism

Recently, a diagnostic strategy using a clinical decision rule, D-dimer testing and spiral computed tomography (CT) was found to be effective in the evaluation of patients with clinically suspected pulmonary embolism (PE). However, the rate of venous thromboembolic complications in the three-month follow-up of patients with negative CT was still substantial and included fatal events. It was the objective to evaluate the safety of withholding anticoagulants after a normal 64-detector row CT (64-DCT) scan from a cohort of patients with suspected PE. A total of 545 consecutive patients with clinically suspected first episode of PE and either likely pre-test probability of PE (using the simplified Wells score) or unlikely pre-test probability in combination with a positive D-dimer underwent a 64-DCT. 64-DCT scanning was inconclusive in nine patients (1.6%), confirmed the presence of PE in 169 (31%), and ruled out the diagnosis in the remaining 367. During the three-month follow-up of the 367 patients one developed symptomatic distal deep-vein thrombosis (0.27%; 95%CI, 0.0 to 1.51%) and none developed PE (0 %; 95%CI, 0 to 1.0%). We conclude that 64-DCT scanning has the potential to safely exclude the presence of PE virtually in all patients presenting with clinical suspicion of this clinical disorder.

Clinically suspected acute pulmonary embolism: a comparison of presentation, radiological features and outcome in patients with and without PE

BACKGROUND

Relatively little is known about prognosis in patients for whom suspected pulmonary embolism (PE) is refuted by imaging.

AIM

This prospective study of suspected PE therefore compared clinico-radiological features and outcome in patients with and without PE.

DESIGN AND METHODS

Computed tomographic pulmonary angiography (CTPA) confirmed or refuted PE in consecutive patients. Clinical, laboratory and radiological features were recorded at baseline, and mortality at 1 year determined. Univariate and multivariate analyses identified variables associated with PE.

RESULTS

PE was diagnosed in 45 patients and refuted in 141. The PE and 'non-PE' groups were similar with regard to extravascular radiology (though consolidation was significantly more common in the PE group [present in 24 (53%) of the PE group and 42 (30%) of the non-PE group, P < 0.01)], comorbidities (no significant differences), and baseline characteristics (only serum D-dimer concentrations were independently associated with PE by multivariate analysis, P = 0.001). Right ventricular dimensions were significantly higher in the PE group, [right ventricular to left ventricular ratio was 0.98 (range 0.64-2.48) in the PE group and 0.92 (range 0.66-1.95) in the non-PE group, P < 0.05]. In the PE group, right ventricular dimensions rose sharply when 10 or more segmental pulmonary arteries were occluded. One year all-cause mortality was 6.7% in the PE group and 13.5% in the non-PE group (no significant difference, P = 0.218).

CONCLUSION

Among a cohort of patients presenting with clinically suspected PE, clinical characteristics, co-morbidities and radiological features were similar when comparing groups with CTPA-proven or CTPA-refuted PE. However RV dimensions, radiological consolidation on imaging and D-dimer levels were significantly higher in the PE group. Patients with suspected PE have a poor prognosis irrespective of whether PE is confirmed. This appears accentuated in patients without PE, a finding possibly under-recognized in clinical practice.

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.

Ventilation/perfusion lung scintigraphy: what is still needed? A review considering technetium-99m-labeled macro-aggregates of albumin

Lung perfusion scintigraphy (LPS) with technetium-99m-labeled macro-aggregates of albumin (Tc-99m-MAA) is well established in the diagnostic of pulmonary embolism (PE). In the last decade, it was shown that single-photon emission computer tomography (SPECT) acquisition of LPS overcame static scintigraphy. Furthermore, there are rare indications for LPS, such as preoperative quantification of regional lung function prior to lung resection or transplantation, optimization of lung cancer radiation therapy, quantification of right-left shunt, planning of intra-arterial chemotherapy, and several rare indications in pediatrics. Moreover, LPS with Tc-99m-MAA is a safe method with low radiation exposure. PE can also be diagnosed by spiral computer tomography (CT), ultrasound, magnetic resonance angiography, or pulmonary angiography (PA, former gold standard). The present review considers all these methods, especially spiral CT, and compares them with LPS with respect to sensitivity and specificity and gives an overview of established and newer publications. It shows that LPS with Tc-99m-MAA represents a diagnostic method of continuing value for PE. In comparison with spiral CT and/or PA, LPS is not to be defeated as mentioned also by the most actual Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) II reports. This applies in particular to chronic or recurring embolisms, whereas currently spiral CT may be of greater value for major or life-threatening embolisms. At present, LPS cannot be replaced by other methods in some applications, such as pediatrics or in the quantification of regional pulmonary function in a preoperative context or prior to radiation therapy. LPS still has a place in the diagnostics of PE and is irreplaceable in several rare indications as described earlier.

Subsegmental pulmonary embolism: value of thoracic ultrasound for diagnosis and follow-up

Timely diagnosis of pulmonary embolism (PE) is crucial because prompt appropriate management can decrease mortality and morbidity. However, the diagnosis of PE is often a challenge because of aspecific clinical presentation and the lack of a single non-invasive diagnostic test sufficiently sensitive for the diagnosis in all suspected cases. The present report describes a 37-year-old woman in whom diagnosis of recurrent subsegmental PE was achieved through subtle integration of imaging techniques including thoracic ultrasound (TUS) that was demonstrated to be of valuable usefulness. We think that TUS may represent an adjunctive technique for diagnosing PE.

Multidetector computed tomographic angiography of the cardiovascular system

The introduction of multidetector computed tomography (MDCT) is considered a dramatic development in CT imaging that has direct implication in the imaging of various systems, in particular the cardiovascular system. The advantages of MDCT are an enormous increase in imaging acquisition speed, more coverage of the patient, and high spatial resolution. This article reviews the recent developments in CT angiography and discusses the clinical application relevant to diagnosis and endovascular treatment of cardiovascular diseases.

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

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

Withholding anticoagulation after a negative computed tomography pulmonary angiogram as a stand-alone imaging investigation: a prospective management study

BACKGROUND

Accurate diagnosis of pulmonary embolism (PE) is essential and it is not clear whether a computed tomography pulmonary angiogram (CTPA) could be used as a stand-alone imaging investigation. The aim of the study was to test the accuracy of the clinical outcome of a negative CTPA as a stand-alone imaging investigation to exclude PE.

METHODS

Five hundred and thirty-four consecutive patients who had a CTPA for diagnosis or exclusion of PE were recruited from March 2003 to October 2004. Four hundred and ninety-four patients had a helical CTPA as a stand-alone imaging investigation for diagnosis or exclusion of PE. A 3-month post-CTPA follow up was carried out in all patients to establish the clinical outcome accuracy of a negative CTPA as a stand-alone imaging investigation.

RESULTS

There were 387 (78.3%) negative and 107 (21.7%) positive CTPA examinations. The average age of the patients was 57.16 years (standard deviation 18.57). Among those with a negative CTPA who survived, one patient had deep vein thrombosis and 342 patients had no evidence of an episode of venous thromboembolism or PE at the 3-month follow up. Thirty-eight patients died within the 3-month follow-up period and one patient's death was attributed to suspected PE. The negative predictive value of a CTPA is 99.5% (95% confidence interval 98.1-99.9%).

CONCLUSION

Helical negative CTPA examination excludes clinically significant PE as a stand-alone imaging investigation. Where concurrent deep vein thrombosis is suspected, lower limb needs to be imaged by ultrasound if the CTPA is negative.

Can multislice CT alone rule out reliably pulmonary embolism? A prospective study

PURPOSE

To evaluate the safety of withholding anticoagulation in patients with suspected acute pulmonary embolism after negative multislice computed tomography (MSCT) pulmonary angiography and lower-limb venography.

MATERIALS AND METHODS

A total of 383 consecutive patients with suspected acute pulmonary embolism were prospectively studied. Patients underwent MSCT pulmonary angiography and lower-limb venography, as well as pulmonary scintigraphy and lower-limb ultrasound examination. Patients with negative MSCT results for both pulmonary embolism and venous thrombosis were not administered anticoagulants and were followed up for 6 months to rule out thromboembolism.

RESULTS

At MSCT, 156 patients were positive for pulmonary embolism, venous thrombosis, or both; 224 were negative; and findings were inconclusive in three. False-negatives were five patients with high probability scintigram and two with venous thrombosis detected at US. A total of 184 patients with negative MSCT and without anticoagulation were followed up for 6 months. During this period of time just one recurrence of pulmonary embolism was detected. The negative predictive value of MSCT pulmonary angiography plus lower-limb venography was 95.8% (183/191).

CONCLUSION

MSCT is efficacious in diagnosing pulmonary embolism, with negative predictive values reported in the literature ranging from 94% to 100%. This enables omission of anticoagulation in patients with suspected pulmonary embolism after negative MSCT findings without the need for other diagnostic tests.

Venous thromboembolism in trauma: an update for the intensive care unit practitioner

Venous thromboembolism (VTE) in trauma patients is a capricious problem that continues to plague trauma surgeons and critical care physicians alike. Pharmacologic preventions of VTE with anticoagulants are often contraindicated in the trauma patient because of risk of bleeding diathesis. Mechanical prophylaxis in the form of venous compression boots often cannot be placed because of external fixators, swelling, and so forth. Providing effective VTE prophylaxis, while at the same time providing definitive care for the trauma patient, can be a nightmare. This review will first discuss the incidence and prevalence of VTE, as well as investigate the condition's diagnosis and treatment. Solutions to frequently encountered clinical dilemmas in managing VTE in trauma patients are considered in the form of frequently asked questions. Diagnostic techniques such as magnetic resonance venography, D-dimer, and various computed tomography methods are evaluated. Recent literature on preventive pharmacologic therapies is explored. The authors also consider whether vena cava filters prevent pulmonary embolism in trauma patients.

Improving the diagnostic performance of lung scintigraphy in suspected pulmonary embolic disease

AIM

to determine the effectiveness of a new imaging algorithm in the investigation of suspected pulmonary embolism (PE).

MATERIALS AND METHODS

A new imaging algorithm for suspected PE was introduced following the installation of a multisection computed tomography (CT) machine at our institution. Before its installation, patients with suspected PE were evaluated with ventilation/perfusion (V/Q) scintigraphy. Subsequently, patients were triaged according to chest radiography (CR) and respiratory history to either lung scintigraphy or CT pulmonary angiography (CTPA). Patients with a normal CR and no history of lung disease were evaluated using perfusion (Q) scintigraphy [ventilation (V) scintigraphy was no longer performed]. Patients with an abnormal CR, asthma or chronic lung disease were evaluated using CTPA. All V/Q images in a continuous 3-year period before the introduction of the new imaging algorithm and all Q images performed in a 3-year period after its introduction were retrospectively reviewed. Imaging reports were categorized into normal, non-diagnostic (low or intermediate probability) or high probability for PE. Patients in the later group who subsequently underwent CTPA, were also reviewed.

RESULTS

After the policy change the percentage of normal scintigrams significantly increased (39 to 60%; p<0.001). There was a non-significant increase in the percentage of high probability scintigrams (15 to 18%; p=0.716). Overall the diagnostic yield of lung scintigraphy improved significantly (54 to 78%; p<0.001).

CONCLUSION

the diagnostic performance of lung scintigraphy can be improved by careful triage of patients to either Q scintigraphy or CTPA based on clinical history and CR findings. Q scintigraphy remains a valuable diagnostic test in the investigation of suspected PE in carefully selected patients.

Pulmonary embolism: accuracy and safety of a negative CT pulmonary angiogram and value of a negative D-dimer assay to exclude CT pulmonary angiogram-detectable pulmonary embolism

This is a retrospective study to determine the accuracy and safety of a negative CT pulmonary angiogram (CTPA) based on clinical outcome and to determine the usefulness of a negative D-dimer assay before CTPA. A total of 483 patients with a negative CTPA study were followed up for 3 months, with the aim of detecting episodes of venous thromboembolism and mortality. Three hundred and forty-nine patients had an immunochromatographic D-dimer assay called 'Simplify', carried out before a CTPA examination. Seventy-eight patients had a negative D-dimer assay and a negative CTPA. Three patients had a negative D-dimer assay and a positive CTPA. All three patients had a moderate pretest clinical probability. Of the 483 patients who had a negative CTPA and a 3-month follow up, 444 (92%) were alive and 39 (8%) had died. Of the 444 patients who were alive, none had any further suspected episode of thromboembolism or had received anticoagulation therapy within the follow-up period. Of those who died, none of the deaths was thought to be as a result of pulmonary embolism (PE). Single-detector helical CT can be used safely as the primary diagnostic test to evaluate PE. Negative Simplify D-dimer assay and low pretest clinical probability exclude CTPA-detectable PE, and a CTPA is unnecessary in this cohort of patients.

Pulmonary Artery CTA

The latest with the introduction of multidetector row computed tomography (MDCT), CT has been firmly established as the modality of choice for imaging the pulmonary arteries, particularly as the de facto first line test for imaging patients with suspected acute pulmonary embolism (PE). Before the introduction of MDCT, remaining concerns regarding CTs accuracy for diagnosis of isolated peripheral emboli had prevented the unanimous acceptance of this test as the reference standard for imaging PE. After a decade of uncertainty, there is now conclusive evidence that CT, if positive, provides reliable confirmation of the presence of PE and, more importantly, if negative effectively rules out clinically significant PE. Current endeavors to streamline and facilitate workflow for CT diagnosis of PE will further improve the acceptance, utility, and importance of this test. Examples include improvements in workflow, CT derivation of right ventricular function parameters for triage and prognostication of patients with acute PE and the comprehensive assessment of patients with acute chest pain for PE, coronary disease, aortic disease, and pulmonary disease by means of a single, contrast enhanced, ECG-synchronized CT scan. Although the diagnosis or exclusion of acute PE is the most common and important application of CT pulmonary angiography, the ease of scan acquisition and the high spatial resolution of modern CT techniques make this test ideally suited for the greatest majority of congenital and acquired, acute and chronic disorders of the pulmonary arteries.

Computed tomography pulmonary angiogram diagnosis of pulmonary embolism

Over the last decade, contrast-enhanced spiral CT has been established as a non-invasive alternative to catheter angiography and is now regarded as the first-line imaging investigation for the diagnosis of pulmonary embolism (PE). The reported sensitivities for the diagnosis of PE of spiral CT vary from 45 to 100% and the specificities vary from 78 to 100%. Prospective outcome studies have shown a high negative predictive value for a single-detector spiral CT for PE. Patients' outcomes were not adversely affected in these studies when anticoagulation was withheld after a negative CT pulmonary angiogram. The main limitation of single-detector spiral CT has been its limited ability to detect isolated subsegmental PE. However, multidetector spiral CT allows evaluation of pulmonary vessels down to sixth-order branches and significantly increases the rate of detection of PE in segmental and subsegmental levels. The interobserver correlations for diagnosis of subsegmental PE with multidetector spiral CT exceed the reproducibility of selective pulmonary angiography. If appropriate equipment is available (multidetector CT), then CT pulmonary angiogram is safe to be used as the first-line imaging investigation for the diagnosis of PE.

Gadolinium-enhanced pulmonary magnetic resonance angiography in the diagnosis of acute pulmonary embolism: a prospective study on 48 patients

OBJECTIVE

Gadolinium-enhanced pulmonary magnetic resonance angiography (MRA) can be an option in patients with a history of previous adverse reaction to iodinated contrast material and renal insufficiency. Radiation is also avoided. The aim of this study is to prospectively compare the diagnostic value of MRA with that of a diagnostic strategy, taking into account catheter angiography, computed tomography angiography (CTA), and lung scintigraphy [ventilation-perfusion (VQ)].

MATERIAL AND METHODS

Magnetic resonance angiography was done in 48 patients with clinically suspected pulmonary embolism (PE) using fast gradient echo coronal acquisition with gadolinium. Interpretation was done with native coronal images and multiplanar maximum intensity projection reconstructions. Results were compared to catheter angiography (n=15), CTA (n=34), VQ (n=45), as well as 6-12 months clinical follow-ups, according to a sequenced reference tree.

RESULTS

The final diagnosis of PE was retained in 11 patients (23%). There were two false negatives and no false positive results with MRA. Computed tomography angiography resulted in no false negatives or false positives. Magnetic resonance angiography had a sensitivity of 82% and a specificity of 100%.

CONCLUSION

In our study, pulmonary MRA had a sensitivity of 82% and a specificity of 100% for the diagnosis of PE, with slightly less sensitivity than CTA. In the diagnostic algorithm of PE, pulmonary MRA should be considered as an alternative to CTA when iodine contrast injection or radiation is a significant matter.

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.

CT pulmonary angiography for the detection of pulmonary embolism: interobserver agreement between on-call radiology residents and specialists (CTPA interobserver agreement)

PURPOSE

The aim of this study was to prospectively determine interobserver agreement between on-call radiology residents and specialists in the interpretation of computed tomographic pulmonary angiography (CTPA).

METHODS

CTPA examinations obtained between January 2002 and March 2003 were interpreted by a radiology resident on call and by two radiology specialists. Agreement was assessed using percentage of agreement between interpreters and by the kappa coefficient. Sensitivity of residents' interpretations was calculated by relating them to the interpretation of Specialist 1, which served as the gold standard.

RESULTS

Of the 81 CTPA examinations evaluated, there was agreement of 93% and 91% for the diagnosis of pulmonary embolism (PE) and of 97% and 85% for the exclusion of PE with Specialist 1 and 2, respectively. The concordance between residents' interpretations and those of Specialist 1 was very high (kappa=.8), and with those of Specialist 2 was high (kappa=.7). In all cases of agreement between the two specialists, there was complete agreement between the specialists' and the residents' intepretations.

CONCLUSIONS

Our study showed good to very good agreement of residents' interpretations with each of the radiology specialists. Therefore, relying on the residents' preliminary interpretations during after-hour calls is reasonable.

Medical management of patients with brain tumors

The most common medical problems in brain tumor patients include the management of seizures, peritumoral edema, medication side effects, venous thromboembolism (VTE), fatigue and cognitive dysfunction. Despite their importance, there are relatively few studies specifically addressing these issues. There is increasing evidence that brain tumor patients who have not had a seizure do not benefit from prophylactic antiepileptic medications. Patients on corticosteroids are at greater risk of Pneumocystis jerovecii pneumonia and may benefit from prophylactic therapy. There is also growing evidence suggesting that anticoagulation may be more effective than inferior vena cava IVC) filtration devices for treating VTE in brain tumor patients and the risk of hemorrhage with anticoagulation is relatively small. Low-molecular weight heparin may be more effective than coumadin. Medications such as modafinil and methylphenidate have assumed an increasing role in the treatment of fatigue, while donepezil and memantine may be helpful with memory loss.