CETARS/CAR Practice Guideline on Imaging the Pregnant Trauma Patient.

Imaging of pregnant patients who sustained trauma often causes fear and confusion among patients, their families, and health care professionals regarding the potential for detrimental effects from radiation exposure to the fetus. Unnecessary delays or potentially harmful avoidance of the justified imaging studies may result from this understandable anxiety. This guideline was developed by the Canadian Emergency, Trauma and Acute Care Radiology Society (CETARS) and the Canadian Association of Radiologists (CAR) Working Group on Imaging the Pregnant Trauma Patient, informed by a literature review as well as multidisciplinary expert panel opinions and discussions. The working group included academic subspecialty radiologists, a trauma team leader, an emergency physician, and an obstetriciangynaecologist/maternal fetal medicine specialist, who were brought together to provide updated, evidence-based recommendations for the imaging of pregnant trauma patients, including patient safety aspects (eg, radiation and contrast concerns) and counselling, initial imaging in maternal trauma, specific considerations for the use of fluoroscopy, angiography, and magnetic resonance imaging. The guideline strives to achieve clarity and prevent added anxiety in an already stressful situation of injury to a pregnant patient, who should not be imaged differently.

Canadian Association of Radiologists Trauma Diagnostic Imaging Referral Guideline.

The Canadian Association of Radiologists (CAR) Trauma Expert Panel consists of adult and pediatric emergency and trauma radiologists, emergency physicians, a family physician, a patient advisor, and an epidemiologist/guideline methodologist. After developing a list of 21 clinical/diagnostic scenarios, a systematic rapid scoping review was undertaken to identify systematically produced referral guidelines that provide recommendations for 1 or more of these clinical/diagnostic scenarios. Recommendations from 49 guidelines and contextualization criteria in the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) for guidelines framework were used to develop 50 recommendation statements across the 21 scenarios related to the evaluation of traumatic injuries. This guideline presents the methods of development and the recommendations for head, face, neck, spine, hip/pelvis, arms, legs, superficial soft tissue injury foreign body, chest, abdomen, and non-accidental trauma.

Water-soluble contrast in the management of adhesive small-bowel obstruction: a Canadian centre's experience with guideline development and implementation.

BACKGROUND: Orally administered water-soluble contrast (WSC) can track resolution of small-bowel obstruction (SBO), but no universal pathway for its use exists. We developed and implemented an evidence-based guideline for the use of WSC in the management of adhesive SBO, to be implemented across hospitals affiliated with the University of Toronto. METHODS: We performed a systematic review and created a clinical practice guideline for WSC use in the management of adhesive SBO. The guideline was approved through consensus by an expert panel and implemented in 2018. We performed a prospective cohort study of guideline implementation at 1 pilot site (a large academic tertiary care centre), facilitated by the centre's acute care general surgery service. Primary outcomes included compliance with the guideline and hospital length of stay (LOS). Secondary outcomes included rates of failure of nonoperative management, morbidity, mortality and readmission for recurrence of SBO within 1 year. Patients with adhesive SBO admitted in 2016 served as a control cohort. RESULTS: We analyzed the data for 152 patients with adhesive SBO admitted to the centre, 65 in 2016 (historical cohort), 56 in January-June 2018 (transitional cohort) and 31 in July-December 2018 (implementation cohort). There was a significant increase in compliance with the WSC protocol in 2018, with the proportion of patients receiving WSC increasing from 45% (n = 25) in the transitional cohort to 71% (n = 22) in the implementation cohort (p < 0.001). The median LOS did not differ across the cohorts (p = 0.06). There was a significantly lower readmission rate in the transitional and implementation cohorts (13 [23%] and 9 [29%], respectively) than in the historical cohort (29 [45%]) (p = 0.04). Among patients assigned to nonoperative management initially, a significantly higher proportion of those who received WSC than those who did not receive WSC went on to undergo surgery (14.6% v. 3.6%, p = 0.01), with no difference in median time to surgery (p = 0.2). CONCLUSION: An evidence-based guideline for WSC use in SBO management was successfully developed and implemented; no difference in LOS or time to surgery was seen after implementation, but rates of immediate operation increased and readmission rates decreased. Our experience shows that implementation of an evidence-based clinical practice guideline is feasible through multidisciplinary efforts and coordination.

The practice of emergency radiology throughout Europe: a survey from the European Society of Emergency Radiology on volume, staffing, equipment, and scheduling.

OBJECTIVES: To obtain information from radiology departments throughout Europe regarding the practice of emergency radiology METHODS: A survey which comprised of 24 questions was developed and made available online. The questionnaire was sent to 1097 chairs of radiology departments throughout Europe using the ESR database. All data were collected and analyzed using IBM SPSS Statistics software, version 20 (IBM). RESULTS: A total of 1097 radiologists were asked to participate, 109 responded to our survey. The response rate was 10%. From our survey, 71.6% of the hospitals had more than 500 beds. Ninety-eight percent of hospitals have an active teaching affiliation. In large trauma centers, emergency radiology was considered a dedicated section. Fifty-three percent of institutions have dedicated emergency radiology sections. Less than 30% had all imaging modalities available. Seventy-nine percent of institutions have 24/7 coverage by staff radiologists. Emergency radiologists interpret cross-sectional body imaging, US scans, and basic CT/MRI neuroimaging in more than 50% of responding institutions. Cardiac imaging examinations/procedures are usually performed by cardiologist in 53% of institutions, while non-cardiac vascular procedures are largely performed and interpreted by interventional radiologists. Most people consider the European Diploma in Emergency Radiology an essential tool to advance the education and the dissemination of information within the specialty of emergency radiology. CONCLUSION: Emergency radiologists have an active role in the emergency medical team. Indeed, based upon our survey, they have to interact with emergency physicians and surgeons in the management of critically ill patients. A broad skillset from ultrasonography and basic neuroimaging is required. KEY POINTS: • At most major trauma centers in Europe, emergency imaging is currently performed by all radiologists in specific units who are designated in the emergency department. • Radiologists in the emergency section at present have a broad skillset, which includes cross-sectional body imaging, ultrasonography, and basic neuroimaging of the brain and spine. • A dedicated curriculum that certifies a subspecialty in emergency radiology with a diploma offered by the European Society of Emergency Radiology demonstrates a great interest by the vast majority of the respondents.

Emergency radiology training in Germany: current status and future directions.

BACKGROUND: Emergency radiology (ER) is an important part of radiology. But what exactly is ER? How can the required competencies be acquired in a good and feasible way? Who should be in charge of this? OBJECTIVES: Discussion of ER contents and suggestions for the improvement of the acquisition of respective competencies during radiology training. MATERIALS AND METHODS: General literature review, in particular the current German blueprint for medical specialist training regulations (Weiterbildungsordnung, WBO 2020), publications by the German Radiological Society (DRG), the European Society of Radiology (ESR), the European Society of Emergency Radiology (ESER) and the American Society of Emergency Radiology (ASER). RESULTS AND CONCLUSIONS: As proof of competence in ER in Germany, confirmation from the authorised residency training supervisor as to whether there is 'competence to act' either 'independently' or 'under supervision' in the case of 'radiology in an emergency situation …, e.g. in the case of polytrauma, stroke, intensive care patients' is sufficient. The ESER refers to all acute emergencies with clinical constellations requiring an immediate diagnosis 24/7 and, if necessary, acute therapy. The ESER and ASER offer, among other things, practical fellowships in specialised institutions, while the ESER complements this with a European Diploma in Emergency Radiology (EDER). On a national level, it would be advisable to use existing definitions, offers and concepts, from the ESR, ESER and ASER. Specialised institutions could support the acquisition of ER competencies with fellowships. For Germany, it seems sensible to set up a separate working group (Arbeitsgemeinschaft, AG) on ER within the DRG in order to drive the corresponding further ER development.

Overnight attending radiologist coverage decreases imaging-related emergency department recalls by at least 90.

PURPOSE: Benefits of overnight attending radiologist final reports are debated, often stating low resident discrepancy rates, usually assessed retrospectively. The objective of this study was to assess the impact of overnight final reporting on the recall rates for patients in the emergency department (ED) receiving overnight imaging. METHODS: Retrospective matched cohorts of two separate years prior (prior-16 and prior-17) and 1 year after (post-18) introduction of overnight attending radiologist final reporting. Patients receiving imaging between 22:00 and 07:00 h and returned to ED within 48 h of initial visit discharge were electronically identified. String matching identified return visits possibly related to imaging completed on first visit. Identified return visit notes were scored by three observers individually. Unclear and discrepant cases were resolved by consensus meeting, using full patient charts where needed. Incidences were provided and logistic regression analysis defined if coverage model was a predictor for recall. Odds ratios were calculated. RESULTS: ED patient count with imaging completed overnight in prior-16 was 9200, in prior-17 was 9543, and in post-18 was 9992. The number of overnight imaging studies performed was respectively 13,883, 14,463, and 15,112. Imaging-related ED recalls were respectively 54, 61, and 7, a decrease with the new coverage model of 89% to true and at least 90% of expected recalls.Logistic regression demonstrated that coverage model was a significant predictor of ED recalls with chi-square of 59.86 and p < 0.001, an R2 of 0.03 (Hosmer and Lemeshow). Compared to post-18, ED patients had an odds ratio of 8.42 (prior-16) and 9.18 (prior-17) to be called back to ED. CONCLUSION: Overnight final reporting significantly decreases ED recalls for patients receiving diagnostic imaging overnight. While numbers are low even prior to rollout, the number should be minimized wherever possible to diminish patient anxiety and discomfort, reduce ED overcrowding and expedite definitive management. KEY MESSAGES/WHAT THIS PAPER ADDS: Section 1: What is already known on this subject • Radiology resident preliminary report discrepancy rates are low. • Overnight attending radiologist coverage is a model increasingly applied in academic and large non-academic centers. • Patient recalls to the ED are a burden to the patient and impact patient throughput in (over)crowded EDs. Section 2: What this study adds • First study to look at the impact of overnight attending final reports on the recall rate for ED patients with overnight imaging performed. • While absolute numbers are low, there is a significant decrease in patients returning to ED for imaging related issues after introducing overnight attending coverage. • Resident autonomy can be preserved and training enhanced while increasing patient safety and comfort.

Emergency Radiology During the COVID-19 Pandemic: The Canadian Association of Radiologists Recommendations for Practice.

Coronavirus Disease 2019 (COVID-19) is the disease caused by the novel coronavirus officially named the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), declared as a pandemic by the World Health Organization on March 11, 2020. The COVID-19 pandemic presents an unprecedented challenge to emergency radiology practice. The continuity of an effective emergency imaging service for both COVID-19 and non-COVID-19 patients is essential, while adhering to best infection control practices. Under the direction of the Board of the Canadian Association of Radiologists, this general guidance document has been synthesized by collaborative consensus of a group of emergency radiologists. These recommendations aim to assist radiologists involved in emergency diagnostic imaging to help mitigate the spread of COVID-19 and continue to add value to patient care in the emergency setting.

Evaluation of Bowel and Mesentery in Abdominal Trauma.

Since the advent of multidetecter computed tomography (CT), radiologist sensitivity in detection of traumatic bowel and mesenteric abnormalities has significantly improved. Although several CT signs have been described to identify intestinal injury, accurate interpretation of these findings can remain challenging. Early detection of bowel and mesenteric injury is important as it alters patient management, disposition, and follow-up. This article reviews the common imaging findings of traumatic small bowel and mesenteric injury.

Effect of rituximab treatment on T and B cell subsets in lymph node biopsies of patients with rheumatoid arthritis.

OBJECTIVES: The exact underlying mechanism of rituximab treatment in patients with RA is poorly defined and knowledge about the effect of B cell depletion on immune cells in secondary lymphoid organs is lacking. We analysed lymphoid tissue responses to rituximab in RA patients. METHODS: Fourteen RA patients received 2 × 1000 mg rituximab intravenously, and lymph node (LN) biopsies were obtained before and 4 weeks after the first infusion. Tissues were examined by flow cytometry, immunohistochemistry and quantitative PCR. LN biopsies from five healthy individuals (HC) served as controls. RESULTS: LN biopsies of RA patients showed increased frequencies of CD21+CD23+IgDhighIgMvariable follicular B cells and CD3+CD25+CD69+ early activated, tissue resident T cells when compared with HCs. After treatment, there was incomplete depletion of LN B cells. There was a significant decrease in CD27-IgD+ naïve B cells, and CD27+IgD+ unswitched memory B cells including the CD27+IgD+IgM+ subset and follicular B cells. Strikingly, CD27+IgD- switched memory B cells persisted in LN biopsies after rituximab treatment. In the T cell compartment, a significant decrease was observed in the frequency of early activated, tissue resident T cells after rituximab treatment, but late activated T cells persisted. B cell proliferation inducing cytokine IL-21 was higher expressed in LN biopsies of RA patients compared with HC and expression was not affected by rituximab treatment. CONCLUSION: Rituximab does not cure RA, possibly due to persistence of switched memory B cells in lymphoid tissues suggesting that factors promoting B cell survival and differentiation need to be additionally targeted.

Dual-Energy CT in Differentiating Nonperforated Gangrenous Appendicitis From Uncomplicated Appendicitis.

OBJECTIVE: The hypothesis of this study was that the use of dual-energy spectral techniques in CT can improve accuracy in the diagnosis of acute gangrenous appendicitis. MATERIALS AND METHODS: This retrospective study included 209 patients with a pathologic diagnosis of appendicitis. Two board-certified abdominal radiologists reviewed 120-kV simulated images, 40-keV virtual monoenergetic images, and color-coded iodine overlay images. Sensitivity, specificity, positive and negative predictive values (PPV and NPV), accuracy, and interobserver agreement were calculated for each set of images. RESULTS: Forty-four patients (21.0%) had histopathologic results positive for gangrenous appendicitis. The sensitivity of 40-kV virtual monoenergetic imaging was 100% (44/44); specificity, 81.2% (134/165); PPV, 58.7% (44/75); NPV, 100% (134/134); accuracy, 85.2%; and interobserver agreement, 0.99. The corresponding values for the iodine overlay imaging datasets were 100% (44/44), 80.0% (132/165), 57.1% (44/77), 100% (132/132), 84.2%, and 0.99 and for 120-kV simulated imaging were 22.7% (10/44), 96.4% (159/165), 62.5% (10/16), 82.4% (159/193), 77.5%, and 0.93. All cases of gangrenous appendicitis had true-positive results of virtual monoenergetic and iodine overlay imaging. There were no false-negative results of virtual monoenergetic or iodine overlay imaging. CONCLUSION: In cases of suspected appendicitis, dual-energy CT that includes virtual monoenergetic and iodine overlay imaging is accurate for confirming and excluding the presence of gangrenous appendicitis with high sensitivity and specificity.

Percutaneous Liver Tumour Ablation: Image Guidance, Endpoint Assessment, and Quality Control.

Liver tumour ablation nowadays represents a routine treatment option for patients with primary and secondary liver tumours. Radiofrequency ablation and microwave ablation are the most widely adopted methods, although novel techniques, such as irreversible electroporation, are quickly working their way up. The percutaneous approach is rapidly gaining popularity because of its minimally invasive character, low complication rate, good efficacy rate, and repeatability. However, matched to partial hepatectomy and open ablations, the issue of ablation site recurrences remains unresolved and necessitates further improvement. For percutaneous liver tumour ablation, several real-time imaging modalities are available to improve tumour visibility, detect surrounding critical structures, guide applicators, monitor treatment effect, and, if necessary, adapt or repeat energy delivery. Known predictors for success are tumour size, location, lesion conspicuity, tumour-free margin, and operator experience. The implementation of reliable endpoints to assess treatment efficacy allows for completion-procedures, either within the same session or within a couple of weeks after the procedure. Although the effect on overall survival may be trivial, (local) progression-free survival will indisputably improve with the implementation of reliable endpoints. This article reviews the available needle navigation techniques, evaluates potential treatment endpoints, and proposes an algorithm for quality control after the procedure.

Preoperative chest radiographs in hip fracture patients: is there any additional value?

PURPOSE: Preoperative screening in hip fracture patients is vital to minimize perioperative complications. Preoperative chest radiographs (POCR) are performed in many hip fracture patients. Earlier research showed that few POCR abnormalities influence perioperative policy. However, no studies in nonelective patient with a specific surgical conditions have been performed. With many hip fractures per year worldwide, a significant cost reduction could be made by performing selective POCR without compromising the quality of care. This study assessed the need for POCR in hip fracture patients. METHOD: Retrospective analysis of low-energy trauma patients was performed aged 18 years and older in the VU University Medical Center for a hip fracture in a 5-year period. All preoperative diagnostics were analyzed. All adjourned operations were evaluated. RESULTS: A total of 642 patients were included, 70% female, matching current epidemiologic figures. The POCR showed abnormalities in 22.6%. In 0.6% the POCR lead to an adjournment of the operation (2.8% of abnormal POCR's). These patients suffered from pneumonia. The POCR in these cases acted as a confirmation of the clinical diagnosis. CONCLUSION: Many factors involving the treatment of hip fracture patients are of importance in minimizing the risk of complications and mortality during and after admission. In 0.6% of all performed POCR's an abnormality leads to the adjournment of the operation. In all four cases the POCR matched the clinical findings. Because the additional value of the POCR in hip fracture patients was limited, we think that its selective use in clinical abnormalities is safe and will reduce unnecessary costs.

Top 50 Highly Cited Articles on Dual Energy Computed Tomography (DECT) in Abdominal Radiology: A Bibliometric Analysis.

This study aims to identify the 50 most highly cited articles on dual energy computed tomography (DECT) in abdominal radiology Thomson Reuters Web of Science All Databases was queried without year or language restriction. Only original research articles with a primary focus on abdominal radiology using DECT were selected. Review articles, meta-analyses, and studies without human subjects were excluded. Fifty articles with the highest average yearly citation were identified. These articles were published between 2007 and 2017 in 12 journals, with the most in Radiology (12 articles). Articles had a median of 7 authors, with all first authors but one primarily affiliated to radiology departments. The United States of America produced the most articles (16), followed by Germany (13 articles), and China (7 articles). Most studies used Dual Source DECT technology (35 articles), followed by Rapid Kilovoltage Switching (14 articles), and Sequential Scanning (1 article). The top three scanned organs were the liver (24%), kidney (16%), and urinary tract (15%). The most commonly studied pathology was urinary calculi (28%), renal lesion/tumor (23%), and hepatic lesion/tumor (20%). Our study identifies intellectual milestones in the applications of DECT in abdominal radiology. The diversity of the articles reflects on the characteristics and quality of the most influential publications related to DECT.

MRI T2* mapping correlates with biochemistry and histology in intervertebral disc degeneration in a large animal model.

PURPOSE: To evaluate intervertebral disc (IVD) degeneration and treatments, an objective diagnostic tool is needed. Recently, T2* relaxation time mapping was proposed as a technique to assess early IVD degeneration, yet the correlation with biochemical content and histological features has not been investigated previously. Our objective was to validate T2* mapping for disc degeneration by correlating this technique with accepted parameters of IVD degeneration. METHODS: Mildly and severely degenerated lumbar discs were obtained from an in vivo large animal study; two healthy goat spines were acquired as control. In total, 48 IVDs were analysed using T2-weighted MRI, T2* relaxation time mapping, biochemical assays, macroscopic and histological scoring. Correlations between variables were expressed with Spearman's rho (ρ) coefficients. RESULTS: A complete range of degenerative grades were obtained (mean histological grade 2.2, range 0-6). A linear positive correlation was observed between T2* relaxation time and glycosaminoglycan content (ρ = 0.64, p < 0.001). T2* relaxation time decreased linearly with increasing degeneration as assessed with Pfirrmann scoring system (ρ = -0.67, p < 0.001), macroscopic (ρ = -0.33, p < 0.05) and histological (ρ = -0.45, p < 0.05) grading. CONCLUSIONS: T2* mapping is an MRI technique for IVD evaluation which allows for measurements on a continuous scale thus minimising observer bias compared to grading systems. Although limited by a small sample size, this study showed a relatively good and linear correlation between T2* relaxation time and accepted parameters of disc degeneration. This suggests that T2* mapping is a promising tool to assess disc degeneration in clinical practice.

Body packing: a review of general background, clinical and imaging aspects.

To avoid detection at border crossings or airport customs, drug trafficking is increasingly performed by intra-corporeal concealment. Body packers may ingest packets of varying size and containing varying drugs (mostly cocaine, heroin and cannabis) mixed with other compounds, while body pushers will insert packets in the rectum or vaginal cavity. Body packing may lead to potential life-threatening complications with acute overdose syndromes after packet rupture and intestinal obstruction with possible ensuing bowel rupture being the most significant complications. Physicians including radiologists should be aware of the capabilities of imaging techniques to screen for presence of drug packets as well as the potential complications. Although conventional radiography has long been and still is the most important imaging modality for screening for presence of intestinal packets, the better test characteristics in conjunction with the decreasing radiation exposure, will likely render computed tomography (CT) more important in the future. For imaging of symptomatic patients, CT already is the modality of choice. Besides these modalities, ultrasound and magnetic resonance imaging will be discussed in this paper, together with more general background and clinical information.

Initial Imaging of Pregnant Patients in the Trauma Bay-Discussion and Review of Presentations at a Level-1 Trauma Centre.

Trauma is the leading non-obstetric cause of maternal and fetal mortality and affects an estimated 5-7% of all pregnancies. Pregnant women, thankfully, are a small subset of patients presenting in the trauma bay, but they do have distinctive physiologic and anatomic changes. These increase the risk of certain traumatic injuries, and the gravid uterus can both be the primary site of injury and mask other injuries. The primary focus of the initial management of the pregnant trauma patient should be that of maternal stabilization and treatment since it directly affects the fetal outcome. Diagnostic imaging plays a pivotal role in initial traumatic injury assessment and should not deviate from normal routine in the pregnant patient. Radiographs and focused assessment with sonography in the trauma bay will direct the use of contrast-enhanced computed tomography (CT), which remains the cornerstone to evaluate the potential presence of further management-altering injuries. A thorough understanding of its risks and benefits is paramount, especially in the pregnant patient. However, like any other trauma patient, if evaluation for injury with CT is indicated, it should not be denied to a pregnant trauma patient due to fear of radiation exposure.

Implementation of the YEARS algorithm to optimise pulmonary embolism diagnostic workup in the emergency department.

BACKGROUND: Excessive use of CT pulmonary angiography (CTPA) to investigate pulmonary embolism (PE) in the emergency department (ED) contributes to adverse patient outcomes. Non-invasive D-dimer testing, in the context of a clinical algorithm, may help decrease unnecessary imaging but this has not been widely implemented in Canadian EDs. AIM: To improve the diagnostic yield of CTPA for PE by 5% (absolute) within 12 months of implementing the YEARS algorithm. MEASURES AND DESIGN: Single centre study of all ED patients >18 years investigated for PE with D-dimer and/or CTPA between February 2021 and January 2022. Primary and secondary outcomes were the diagnostic yield of CTPA and frequency of CTPA ordered compared with baseline. Process measures included the percentage of D-dimer tests ordered with CTPA and CTPAs ordered with D-dimers <500 µg/L Fibrinogen Equivalent Units (FEU). The balancing measure was the number of PEs identified on CTPA within 30 days of index visit. Multidisciplinary stakeholders developed plan- do-study-act cycles based on the YEARS algorithm. RESULTS: Over 12 months, 2695 patients were investigated for PE, of which 942 had a CTPA. Compared with baseline, the CTPA yield increased by 2.9% (12.6% vs 15.5%, 95% CI -0.06% to 5.9%) and the proportion of patients that underwent CTPA decreased by 11.4% (46.4% vs 35%, 95% CI -14.1% to -8.8%). The percentage of CTPAs ordered with a D-dimer increased by 26.3% (30.7% vs 57%, 95% CI 22.2% 30.3%) and there were two missed PE (2/2695, 0.07%). IMPACT: Implementing the YEARS criteria may safely improve the diagnostic yield of CTPAs and reduce the number of CTPAs completed without an associated increase in missed clinically significant PEs. This project provides a model for optimising the use of CTPA in the ED.

Starting an Emergency Radiology Division: Scheduling and Staffing, Compensation, and Equity and Parity.

Establishing an emergency radiology division in a practice that has long-standing patterns of operational routines comes with both challenges and opportunities. In this article, considerations around scheduling and staffing, compensation, and equity and parity are provided with supporting literature references. Furthermore, a panel of experts having established, grown and managed emergency radiology divisions in North America and Europe share their experiences through a question and answer format.

Acute pulmonary embolism: effect of a computer-assisted detection prototype on diagnosis--an observer study.

PURPOSE: To assess the effect of a computer-assisted detection (CAD) prototype on observer performance for detection of acute pulmonary embolism (PE) with computed tomographic (CT) pulmonary angiography. MATERIALS AND METHODS: In this institutional review board-approved retrospective study, six observers with varying experience evaluated 158 PE-negative and 51 PE-positive CT pulmonary angiographic studies (mean age, 57 years; 111 women, 98 men) obtained consecutively during nights and weekends. Observers were asked to determine the presence of PE and to rank their diagnostic confidence without CAD and subsequently with CAD within a single reading session. Reading time was separately measured for both readings. Reader data were compared with an independent standard established by two readers, with a third in case of discordant results. Statistical evaluation was performed on a per-patient basis by using logistic regression for repeated measurements and Pearson correlation. RESULTS: With CAD, there was a significant increase in readers' sensitivity (P = .014) without loss of specificity (P = .853) on a per-patient basis. CAD assisted the readers in correcting an initial false-negative diagnosis in 15 cases, with the most proximal embolus at the segmental level in four cases and at the subsegmental level in 11 cases. In eight cases, readers accepted false-positive CAD candidate lesions on scans negative for PE, and in one case, a reader dismissed a true-positive finding. Reading time was extended by a mean of 22 seconds with the use of CAD. CONCLUSION: At the expense of increased reading time, CAD has the potential to increase reader sensitivity for detecting segmental and subsegmental PE without significant loss of specificity.