C. Craig Blackmore

Systematic Review: Computed Tomography and Ultrasonography To Detect Acute Appendicitis in Adults and Adolescents

Context Is computed tomography or ultrasonography better for diagnosing acute appendicitis? Contribution This meta-analysis summarized data from 22 prospective studies that compared results of computed tomography, ultrasonography, or both with surgical findings or clinical follow-up in patients with suspected appendicitis. Computed tomography findings (positive likelihood ratio, 13.3 [95% CI, 9.9 to 17.9]) increased the certainty of diagnosis more than did ultrasonography (positive likelihood ratio, 5.8 [CI, 3.5 to 9.5]). Cautions All studies had significant limitations that probably inflated estimates of diagnostic accuracy, such as inadequate blinding of the reference standard and pathologic verification of disease only in patients with positive test results. The Editors Acute appendicitis is one of the most common acute surgical conditions in the United States; 250000 appendectomies are performed each year (1). Although early clinical evaluation and surgical intervention are mandatory, conventional diagnostic approaches such as history taking, physical examination, and routine laboratory tests are not always accurate (2, 3). Therefore, imaging tests are commonly used to improve diagnostic accuracy (4). In addition, compared with inpatient observation and serial basic laboratory tests, appendiceal imaging may be relatively inexpensive (5). During the past decade, appendiceal computed tomography and graded compression ultrasonography (6) have gained widespread use (4). Appropriateness criteria prepared by the American College of Radiology recommended graded compression ultrasonography as a screening test for most patients with suspected appendicitis (7). These criteria also recommended that computed tomography be used only in patients who are obese; have a rigid, noncompressible abdomen; or are thought to have appendicitis complicated by abscess (7). Published review articles have also supported the initial use of ultrasonography and have advised that computed tomography be reserved for patients with inconclusive sonogram findings (4, 8). However, in a survey of practicing emergency radiologists, the selection of appendiceal imaging varied, and there was no consensus about the best imaging approach for patients with a typical or atypical presentation of appendicitis (9). Most published studies of appendiceal imaging have evaluated the diagnostic accuracy of a single method, either computed tomography or ultrasonography; only a few studies have directly compared the 2 tests (10-13). In addition, no recent systematic review or meta-analysis has critically appraised currently available data on appendiceal imaging. Although 1 meta-analysis on appendiceal ultrasonography was conducted in 1994 (14), most of the included studies evaluated both children and adults, and the meta-analysis did not explore methodologic quality. We conducted a meta-analysis of the diagnostic accuracy of appendiceal computed tomography and ultrasonography in adults and adolescents. We explored the following 2 questions: 1) What is the diagnostic accuracy of computed tomography and ultrasonography? 2) What are the strengths and limitations of the current literature? Methods Study Identification We searched MEDLINE and EMBASE for English- and nonEnglish-language literature published from January 1966 through December 2003. The detailed search strategy can be found in the Appendix. We also manually searched the reference lists of eligible studies, review articles, and textbooks and consulted with experts in diagnostic imaging. Study Selection Two of the authors reviewed the pertinent studies to determine eligibility. We included only studies that prospectively evaluated computed tomography or graded compression ultrasonography in adults and adolescents (patients 14 years of age) who had suspected appendicitis, followed by surgical and pathologic confirmation or clinical follow-up. We expanded the original inclusion criterion from age 18 years or older to age 14 years or older in March 2002 after performing the pilot MEDLINE search, when it became clear that many studies included both adolescents and adults. The 6 computed tomography studies and 4 ultrasonography studies identified by using the original criterion of 18 years of age or older were examined separately in a sensitivity analysis. Data Abstraction Two independent reviewers abstracted relevant data for English-language articles. For nonEnglish-language articles, data were abstracted by a single reviewer working with a physician who was a native speaker of the relevant language. Abstractors were not blinded to journals. On the basis of clinical presentation before the imaging test, we categorized studies into 2 groups: atypical, which referred to studies enrolling only patients with an atypical presentation for appendicitis, and suspected, which referred to studies enrolling patients with both typical and atypical presentations. For 1 computed tomography study (13), we abstracted the combined test results using 3 different computed tomography protocols because this was how the authors published the data. Inconsistencies between reviewers were resolved by discussion, and a third reviewer adjudicated unresolved disagreements. When we could not extract or appropriately analyze pertinent data from published articles, we contacted a corresponding author for clarification. Assessment of Study Quality and Applicability We assessed study quality and applicability by using the checklist prepared for the Cochrane Methods Group on Systematic Review of Screening and Diagnostic Tests (15). Since we included studies that had a combined reference standard of surgical and pathologic confirmation or medical follow-up, we also abstracted how each study obtained medical follow-up on patients who did not proceed to surgery. If there was no explicit description of how such patients were followed after leaving the emergency department, we considered the follow-up inadequate. Data Synthesis and Analysis For each study, we constructed a 2 2 contingency table consisting of true-positive (TP), false-positive (FP), false-negative (FN), and true-negative (TN) results according to an imaging test and reference standard (surgery or clinical follow-up). We then calculated sensitivity as TP/(TP + FN), specificity as TN/(FP + TN), the likelihood ratio for a positive test result as (TP/[TP + FN])/(FP/[FP + TN]), and the likelihood ratio for a negative test result as (FN/[TP + FN])/(TN/[FP + TN]). We explored the heterogeneity of sensitivity and specificity between studies by comparing confidence intervals of individual study findings with the summary estimates, using forest plots (16). For likelihood ratios, we estimated the statistics Q and I2 as means of quantifying heterogeneity among studies, and we considered the studies heterogeneous if the I2 was more than 30% (17). The summary sensitivity and specificity were calculated as follows, respectively, regardless of heterogeneity: the sum of TPs/(TPs + FNs) and the sum of TNs/(FPs + TNs) (18). We calculated the summary likelihood ratio statistics using the MantelHaenszel fixed-effects model for computed tomography studies because there was no statistical evidence of heterogeneity (positive likelihood ratio: Q = 9.16 [P> 0.2], I2 = 0% [CI, 0% to 58%]; negative likelihood ratio: Q = 7.38 [P> 0.2], I2 = 0% [CI, 0% to 58%]) (19). We used the DerSimonianLaird random-effects model to combine the likelihood ratios for ultrasonography studies since statistical evidence of heterogeneity was suggested (positive likelihood ratio: Q = 86.33 [P< 0.001], I2 = 85% [CI, 76% to 90%]; negative likelihood ratio: Q = 52.75 [P< 0.001], I2 = 75% [CI, 59% to 85%]) (20). Sensitivity Analysis Three computed tomography studies (10, 21, 22) and 3 ultrasonography studies (10, 11, 23) reported nondiagnostic results of imaging tests, that is, cases in which interpreters could not judge whether test results were positive or negative. Nondiagnostic results, if any, were excluded from the calculation of statistics in the main analysis. In a sensitivity analysis, we estimated sensitivity and specificity considering the numbers of nondiagnostic studies as false-negative and false-positive results, respectively, to evaluate a worst-case scenario. Also, we performed preplanned subgroup analyses for studies of adult participants ( 18 years of age), studies with different patient presentations at enrollment (suspected vs. atypical), and studies that included a high percentage of women (>67%). Role of the Funding Sources The funding sources had no role in study design, conduct, data collection, data analysis, data interpretation, or reporting or in the decision to submit the manuscript for publication. Data Synthesis The MEDLINE search identified 316 potentially relevant articles (Figure 1). We excluded 199 studies by scanning the titles and abstracts. We then retrieved and reviewed 117 full reports for inclusion and excluded 97 studies: 80 studies because they enrolled patients younger than 14 years of age, 10 studies because they were retrospective, 5 studies because they were casecontrol studies or case series, and 2 studies for other reasons. Subsequently, the EMBASE search identified 81 potentially relevant articles, 63 of which were excluded after we scanned the titles and abstracts. We then retrieved and reviewed 18 full reports for inclusion and excluded 16 studies: 10 studies enrolling patients younger than 14 years of age, 3 retrospective studies, 1 case series, 1 review article, and 1 study from which pertinent data could not be obtained because it evaluated only the combined diagnostic accuracy of both computed tomography and preceding clinical examinations. Lists of the excluded articles can be found in the Appendix. Figure 1. Article selection process. Study Characteristics We identified 12 studies of computed tomography (10-13, 21, 22, 24-29) and 14 studies of ultrasonography (10-13, 23, 30

Pleural fluid volume estimation: A chest radiograph prediction rule

RATIONALE AND OBJECTIVES We devised a prediction rule for estimating pleural effusion volume on the basis of posteroanterior and lateral chest radiographs. METHODS A prediction rule was devised for estimating pleural effusion volume on the basis of the presence or absence of a meniscus on chest radiographs. The rule was tested and validated using separate data sets obtained from a retrospective review of patients having both a chest radiograph and computed tomography (CT) scan (the gold standard) within 24 hr of each other. The accuracy of the prediction rule and the degree of interobserver agreement between the two independent readers were determined. RESULTS For the test and validation sets, the weighted accuracies of the prediction rule were 86% and 85%, respectively. The respective weighted interobserver agreements were 97% and 88%. Pleural effusions became visible as a meniscus on the lateral chest radiograph at a volume of approximately 50 ml; at a volume of 200 ml, the meniscus could be identified on the posteroanterior radiograph. At a volume of about 500 ml, the meniscus obscured the hemidiaphragm. CONCLUSION The volume of a pleural effusion can be estimated from the chest radiograph appearance with a reasonable degree of accuracy.

Helical CT in the primary trauma evaluation of the cervical spine : an evidence-based approach

Abstract This review provides a summary of the cost-effectiveness, clinical utility, performance, and interpretation of screening helical cervical spine CT for trauma patients. Recent evidence supports the use of helical CT as a cost-effective method for screening the cervical spine in high-risk trauma patients. Screening cervical spine CT can be performed at the time of head CT to lower the cost of the evaluation, and when all short- and long-term costs are considered, CT may actually save money when compared with traditional radiographic screening. In addition to having higher sensitivity and specificity for cervical spine injury, CT screening also allows more rapid radiological clearance of the cervical spine than radiography. Patients who are involved in high-energy trauma, who sustain head injury, or who have neurological deficits are candidates for CT screening. Screening with CT may enhance detection of other potentially important injuries of the cervical region.

Clearing the cervical spine in obtunded patients.

Study Design. Retrospective cohort study. Objective. To determine the frequency of injuries missed by initial computed tomography (CT) of the cervical spine in obtunded blunt trauma victims. Summary of Background Data. Optimal method for excluding cervical spine injury in obtunded trauma patients remains controversial. Trauma centers show marked variation in spine clearance protocols. Methods. We reviewed medical records of consecutive obtunded blunt trauma victims admitted over 2 years to a level 1 trauma center and selected patients who had CT imaging of the cervical spine during their initial emergency room evaluation. We excluded patients in whom this study identified an injury and also patients who became examinable before subsequent imaging with upright cervical spine radiographs, as required by institutional protocol. Using composite reference standard of cervical injury diagnosed by subsequent imaging or clinical examinations by the time of discharge from the hospital, we evaluated the frequency and type of injuries missed by the initial CT and the delay in spine clearance due to additional imaging. Results. Of 590 screened patients, 367 met the inclusion and exclusion criteria. The study cohort had mean age 40.2 years (SD 20.8), 75.5% males, mean Glasgow Coma Scale score 5.9 (SD 3.4), and mean Injury Severity Scale score 24.5 (SD 10). Initial CT imaging failed to identify an injury in 1 patient, for a false negative rate of 0.3% (1/367): a cervical cord contusion identified on subsequent physical examination, confirmed by magnetic resonance imaging, and managed nonoperatively. Upright cervical spine radiographs did not identify any injuries missed by CT, but they delayed spine clearance by a mean of 2.6 days and by more than 48 hours in 42% of the patients. Conclusion. Initial CT imaging identified all unstable cervical spine injuries in obtunded trauma patients. Subsequent upright radiographs did not identify any additional injuries but significantly delayed spine clearance.

Evidence-based approach to using CT in spinal trauma

Computed tomography has revolutionized the diagnosis and treatment planning of the acutely injured spine. In the cervical spine, its appropriate use can improve outcome and save money. Although there are no clinical prediction rules validated outside of the cervical spine, these proven capabilities have been extrapolated to the thoracolumbar spine.

Economic analyses of radiological procedures: A methodological evaluation of the medical literature

OBJECTIVE Increasing pressure to curb health care costs has led to considerable interest in economic analyses, including both cost-effectiveness and cost-benefit analyses. Numerous economic analyses of radiological procedures have appeared in both the radiology and non-radiology literature. The objective of this study was to evaluate the methodological quality of economic analyses of radiological procedures published in the non-radiology medical literature during the years 1990 1995. METHODS Original investigations from the medical (non-radiological) literature that include economic analyses of radiological interventions were identified from a computerized literature search. Each economic analysis article was evaluated by two independent reviewers for adherence to ten methodological criteria. The criteria were derived from review of the medical and radiological economic analysis methodology literature and consisted of the following: (1) Comparative options stated; (2) perspective of analysis defined; (3) outcome measure identified; (4) cost data included; (5) source of cost data stated; (6) long term costs included; (7) discounting employed; (8) summary measure provided; (9) incremental computation method used; and (10) sensitivity analysis performed. The results were compared to a previous study that evaluated the radiological literature. RESULTS Of the 56 articles in the medical literature that included economic analyses of radiological procedures, only eight (14%) conformed to all ten methodological criteria. The cost data (98%) and comparative options (89%) criteria exhibited high compliance, while the perspective of analysis (25%) and discounting (32%) criteria had relatively low compliance. Agreement between the reviewers was excellent (kappa = 0.88). CONCLUSIONS Published economic analyses of radiology procedures usually do not meet accepted methodological standards.

Economic analyses in obstetrics and gynecology: A methodologic evaluation of the literature☆

Objective To evaluate the methodology of the cost-effectiveness and cost-benefit literature in obstetrics and gynecology. Data Sources We performed a MEDLINE search of the general and subspecialty obstetrics and gynecology journals for the years 1990 through 1996. Methods of Study Selection Original investigations including cost-effectiveness or cost-benefit were evaluated by two reviewers for adherence to ten minimum methodologic standards derived by a review of guidelines for medical economic analyses. The major criteria considered included: 1) provision of comparative options, 2) statement of analytic perspective, 3) presentation of cost data, 4) identification of outcome measure, 5) use of summary measure of economic effectiveness or benefit, and 6) performance of a sensitivity analysis. The minor criteria evaluated included: 1) statement of source of cost data, 2) inclusion of long-term costs, 3) use of discounting, and 4) calculation of an incremental summary measure. Tabulation, Integration, and Results Ninety-eight articles that included cost-benefit or cost-effectiveness analyses were identified. The mean number of major and minor principles adhered to were 3.6 and 1.0, respectively. Five publications (5.1%) conformed to all ten major and minor criteria, whereas nine (9.2%) articles used all six major criteria. The provision of cost data (94.8%) and statement of comparative options (96.9%) were the major principles most frequently adhered to, whereas the use of discounting (10.2%) and statement of analytic perspective (19.3%) showed the lowest compliance. Agreement between the reviewers was excellent (kappa .87). Conclusion Published economic analyses in the obstetrics and gynecology literature seldom adhere to all recommended methodologic guidelines. Further training in the methodology of cost-effectiveness analysis is needed within the specialty.

Indeterminate CT Angiography in Blunt Thoracic Trauma: Is CT Angiography Enough?

OBJECTIVE The primary objective of our study was to determine whether catheter angiography is needed to exclude aortic and intrathoracic great vessel injury when CT angiography (CTA) findings are indeterminate (mediastinal hematoma without direct evidence of aortic or intrathoracic great vessel injury). The secondary objective was to devise a classification scheme for mediastinal hematomas. MATERIALS AND METHODS This study is a retrospective analysis of patients presenting with blunt trauma over 4.5 years at a level 1 trauma center. Indeterminate CTA findings in patients with blunt injury were identified through a database search of imaging reports. CTA findings and final outcomes, including catheter angiography and clinicopathologic records, were reviewed independently by blinded observers. RESULTS One hundred seven patients (age range, 11-88 years) met the inclusion criteria. Seventy-two (age range, 15-88 years) had a reference standard of subsequent catheter angiography, and 35 subjects (age range, 11-87 years) did not undergo catheter angiography and therefore had a reference standard of clinicopathologic review. No subjects with isolated mediastinal hematoma on CTA had aortic or intrathoracic great vessel injury, for a positive predictive value of 0% (95% CI, 0-0.028). Using our proposed classification scheme, we found a direct correlation between the percentage of cases that underwent catheter angiography and hematoma severity. CONCLUSION When CTA is indeterminate in blunt thoracic trauma, conventional angiography is unlikely to show an aortic or intrathoracic great vessel injury and may be unnecessary. A grading system for mediastinal hematomas could help triage patients to conventional angiography when further imaging is desired.

Evidence-based imaging

Evidence-based imaging , Evidence-based imaging , کتابخانه دانشگاه علوم پزشکی و خدمات درمانی بوشهر

Do initial radiographs agree with crash site mechanism of injury in pelvic ring disruptions? A pilot study.

Objective: Direction of injury force inferred from pelvic radiographs may be used in trauma care to predict associated injuries and guide intervention. Our objective was to compare injury direction determined from anteroposterior (AP) pelvic radiographs with injury forces determined from crash site investigation. Materials and Methods: We studied all 28 subjects from the Crash Injury Research Engineering Network (CIREN) database who met inclusion criteria of pelvic ring disruption, single-event crash, restrained front-seat occupant, diagnostic-quality pelvic radiography, and complete crash investigation data. Assessment of diagnostic quality of pelvic radiography was made by 2 radiologists who were blinded to all other subject information. Crash site investigation data included principal direction of force (PDOF), crash magnitude, and passenger compartment intrusion. An orthopedic trauma surgeon and a fellowship-trained emergency radiologist independently assessed the pelvic radiographs to determine the injury PDOF and the Young-Burgess and Tile fracture classifications, with disputes resolved by an additional emergency radiologist. Agreement between injury forces and pelvic radiographs was assessed using the kappa statistic. Results: The PDOF was anterior in 9 (32%) and lateral in 19 (68%) subjects. The readers agreed with the crash primary direction of force in 21 (75%) subjects (κ = 0.42). In subjects with lateral PDOF, agreement was 89% (17/19) compared to 44% for anterior PDOF (4/9). Interobserver agreement for the Young and Tile classification schemes was moderate (weighted kappa 0.44 and 0.54, respectively). Conclusion: Crash site investigation and pelvic radiography may provide conflicting information about primary direction of injuring forces. Presumed anterior impact based on PDOF is not in consistent agreement with the pattern of injury evident on the AP pelvic radiograph.