Need For Computed Tomography Imaging Research Articles

Comparison of radiographs and computed tomography (CT) imaging for preoperative evaluation and planning for shoulder arthroplasty

BackgroundThe purpose of this study was to determine if addition of CT to axillary radiographs (AXR) alters preoperative decision making for shoulder arthroplasty. MethodsPreoperative deidentified images (XR alone and XR with CT) of 50 patients with glenohumeral arthritis were reviewed independently by 3 reviewers in a blinded fashion. Each reviewer graded images for glenoid wear pattern as simple (Walch A1 or B1) or advanced [A2, B2, C]), adequacy of AXR and need for advanced imaging. The reviewers determined a preoperative plan for all patients based on XR alone vs. XR and CT including the arthroplasty type (anatomic or reverse total shoulder) and their plan for treating glenoid wear (eccentric or standard reaming vs. bone graft or augment). Kappa values (κ) were calculated to determine inter-rater agreement and consistency among multiple reviewers. Fisher's exact test was used to assess any difference in preoperative plan once the shoulders were separated into simple and advanced glenoid wear patterns. ResultsThe 3 reviewers agreed that quality of AXRs was significantly inadequate (P < .001) for assessing glenoid wear in advanced glenoid wear patterns compared to simple wear patterns. Following evaluation on AXRs alone, the need for CT imaging was significantly higher in advanced glenoid wear patterns compare to simple ones (81% vs. 31%; P < .001). The addition of CT images did not result in a significant change to the preoperative plan in simple glenoid wear patterns but in advanced glenoid wear, addition of CT can change the preoperative plan with respect to arthroplasty type and/or strategy for addressing glenoid wear. ConclusionAxillary radiographs are often inadequate for preoperative planning in shoulder arthritis with advanced glenoid wear patterns (Walch A2, B2, C types). Addition of CT imaging to radiographs in shoulder arthritis with advanced glenoid wear can affect the preoperative decision with respect to type of shoulder arthroplasty and/or plan for addressing glenoid wear (reaming, bone graft or augmented glenoids). Level of evidenceLevel IV

Application of the Canadian Computed Tomography Head Rule to Patients With Minimal Head Injury

Two clinical decision rules, the Canadian CT Head Rule and the New Orleans Criteria, set the standard to guide clinicians in determining which patients with minor head trauma need computed tomography (CT) imaging. Both rules were derived with patients with minor head injury who had had a loss of consciousness or witnessed disorientation. No evidence exists for evaluating patients and need for CT imaging with minimal head injury; that is, patients who had a head injury but no loss of consciousness or disorientation and therefore would have been excluded from the Canadian CT Head Rule and New Orleans Criteria trials. We evaluate the Canadian CT Head Rule in patients with head injury without loss of consciousness or witnessed disorientation (minimal head injury). We studied a prospective convenience sample of patients with minimal head injury who received head CTs as part of their evaluations in the emergency department (ED). Participants were enrolled after head CT was ordered, but before the physician received the imaging results. Physicians were surveyed on their clinical reasoning for ordering imaging in this low-risk cohort of patients. Physicians surveyed consisted of ED attending physicians and senior-level emergency medicine residents. Final patient disposition was recorded when it became available. Patients with positive CT findings had their medical records reviewed for specific disposition, admission length of stay, ICU stay, and any operative or procedural interventions. Two hundred forty patients with minimal head injury were enrolled. Five patients (2.1%) had head CTs that were positive for intracranial hemorrhage. All instances of intracranial hemorrhage occurred in patients who were at high or moderate risk by the Canadian CT Head Rule (2 high risk [age], 3 moderate risk [mechanism]). No patient with intracranial hemorrhage went to the ICU or underwent any intervention; the average hospital length of stay was 1.25 days. The Canadian CT Head Rule was 100% sensitive (95% confidence interval 40% to 100%) and 29% specific (95% confidence interval 23% to 35%) for the presence of intracranial hemorrhage. Physicians listed their own reassurance (24.6%), patient reassurance (24.2%), patient expectation (14.6%), and reduction of legal liability (11.7%) as the rationale for ordering head CT in patients with minimal head injury. Shared decisionmaking was used in 51% of cases. Risk of intracranial hemorrhage in patients with minimal head injury was very low, and even in patients found to have an intracranial hemorrhage, none had any serious adverse outcome (eg, death, intubation, prolonged hospitalization, surgical procedure). The Canadian CT Head Rule was 100% sensitive in this small cohort of patients with minimal head injury. Among our study cohort, which specifically included only patients who had CT scanning, applying the Canadian CT Head Rule may have reduced the need for CT, potentially saving costs and resources. However, because many patients with minimal head injury who present to the ED may not have CTs, it is unclear what effect the broad application of this rule would have on overall CT use. Providers' rationale for obtaining CT was multifactorial. These represent barriers that may need to be overcome before physicians are comfortable changing CT ordering patterns in this group of head injury patients.

Predicting the need for CT imaging in children with minor head injury using an ensemble of Naive Bayes classifiers

Using an automatic data-driven approach, this paper develops a prediction model that achieves more balanced performance (in terms of sensitivity and specificity) than the Canadian Assessment of Tomography for Childhood Head Injury (CATCH) rule, when predicting the need for computed tomography (CT) imaging of children after a minor head injury. CT is widely considered an effective tool for evaluating patients with minor head trauma who have potentially suffered serious intracranial injury. However, its use poses possible harmful effects, particularly for children, due to exposure to radiation. Safety concerns, along with issues of cost and practice variability, have led to calls for the development of effective methods to decide when CT imaging is needed. Clinical decision rules represent such methods and are normally derived from the analysis of large prospectively collected patient data sets. The CATCH rule was created by a group of Canadian pediatric emergency physicians to support the decision of referring children with minor head injury to CT imaging. The goal of the CATCH rule was to maximize the sensitivity of predictions of potential intracranial lesion while keeping specificity at a reasonable level. After extensive analysis of the CATCH data set, characterized by severe class imbalance, and after a thorough evaluation of several data mining methods, we derived an ensemble of multiple Naive Bayes classifiers as the prediction model for CT imaging decisions. In the first phase of the experiment we compared the proposed ensemble model to other ensemble models employing rule-, tree- and instance-based member classifiers. Our prediction model demonstrated the best performance in terms of AUC, G-mean and sensitivity measures. In the second phase, using a bootstrapping experiment similar to that reported by the CATCH investigators, we showed that the proposed ensemble model achieved a more balanced predictive performance than the CATCH rule with an average sensitivity of 82.8% and an average specificity of 74.4% (vs. 98.1% and 50.0% for the CATCH rule respectively). Automatically derived prediction models cannot replace a physician's acumen. However, they help establish reference performance indicators for the purpose of developing clinical decision rules so the trade-off between prediction sensitivity and specificity is better understood.

New findings in the semicircular canal dehiscence syndrome

We describe a young patient with conductive hearing loss (CHL) associated with a posterior semicircular canal dehiscence (PCD) next to a large jugular bulb. Vestibular evoked myogenic potentials (VEMPs), audiogram, and computed tomography (CT) confirmed the diagnosis. The contralateral ear also showed lowered VEMP thresholds and PCD on CT, but no CHL. Increased vigilance is warranted in the evaluation of CHL in patients with uninfected, normal-appearing ears. PCD as a cause of CHL is just beginning to surface in the otologic literature. This case, along with two other recent case series, demonstrates the need for CT imaging in cases of atypical CHL.

Evaluating Outcomes of Endoleak Discrepancies Between Computed Tomography Scan and Ultrasound Imaging After Endovascular Abdominal Aneurysm Repair

Endovascular repair for abdominal aortic aneurysm (EVAR) requires regular surveillance to ensure long-term durability. To understand the clinical consequence of discrepancies in endoleak detection between computed tomographic angiography (CTA) and duplex ultrasound (DUS) imaging, this study evaluated patients who underwent EVAR. The aim of the present study was to determine whether these discrepancies affected the long-term outcome after EVAR, and whether DUS predicted the need for re-intervention on the basis of other markers despite missing endoleaks. A review of the prospectively maintained database was completed to capture all EVAR procedures performed between October 1999 and June 2009. Patients were routinely evaluated with computed tomography (CT) and DUS imaging within 30 days after the procedure and intermittently at 6-12 month intervals after treatment. DUS imaging was evaluated with attention toward maximum aneurysm diameter, presence of an endoleak, and compared with findings on simultaneous contrast CT imaging. The database and patient records identified 1,062 EVARs in 992 patients who underwent 3,120 imaging encounters through the surveillance protocol. Of these 3,120 encounters, 610 had both CT scan and ultrasound at the same visit. Contrast material was not used in 49 CT scans, leaving 561 encounters for comparing contrast CT imaging with DUS results. CT and DUS detection of endoleaks correlated in 442 encounters (78.8%). Discrepancies occurred in 119 encounters (21.2%) as follows: CT scan only endoleak in 17.8% (N = 100; type I = 6, type II = 91, and type III = 3) and DUS only endoleak in 3.4% (N = 19; type II = 19) encounters. Of these 119 encounters, 99 (17.6%) did not require secondary interventions. Eventually, 15 patients required intervention after 20 discrepancy encounters (3.6%): 11 patients continued with the surveillance protocol through CT or DUS imaging, whereas four were observed by CT imaging only. Considering these 11 patients, DUS eventually detected an endoleak on subsequent visits in five patients, DUS identified an increase in aneurysm diameter in four patients, and DUS never identified the type II endoleaks in two patients. When the endoleak raised concern or the aneurysm enlarged, we undertook 19 secondary interventions in these 15 patients: vessel embolization (N = 8), iliac extenders (N = 5), graft relining (N = 3), graft explants (N = 2), and proximal cuff (N = 1). Although three ruptures occurred in our entire treatment experience, no ruptures occurred in patients who maintained the prescribed surveillance protocol. Surveillance after EVAR is necessary because secondary interventions are sometimes required. Although DUS has lower sensitivity in detecting endoleaks, comparison with CT findings can identify the appropriate patients for DUS surveillance only. Even considering the discrepancies between CT imaging and DUS, repeated DUS surveillance might identify an unstable aneurysm that requires further intervention. Although DUS has not been established as an exclusive surveillance tool, it can be used to effectively monitor patients after EVAR with reduced need for CT imaging.

Can a State-of-the-Art d-Dimer Test Be Used to Determine the Need for CT Imaging in Patients Suspected of Having Pulmonary Embolism?

Rationale and Objectives The purpose of this study was to determine whether a simple rapid blood test can obviate computed tomography (CT) in a sizable percentage of patients suspected of having pulmonary embolism, based on the hypothesis that negative d-dimer results could eliminate any further search for pulmonary embolism. Materials and Methods At the authors' institution, 2,121 sequential patients underwent a whole-blood antibody agglutination test for cross-linked fibrin degradation products ( d-dimer). Of these patients, 844 had positive test results and were not further considered. A retrospective review included reports of all multisection combined CT venographic and pulmonary angiographic studies obtained within 48 hours of the d-dimer assay for the 1,277 patients with negative d-dimer results; 229 (18%) of these 1,277 patients underwent combined CT venography and pulmonary angiography, usually within 24 hours. Results Retrospective review of the imaging examinations that were discrepant with the d-dimer results revealed only three false-negative d-dimer results. Of the 229 patients in whom combined CT venography and pulmonary angiography was performed for suspected pulmonary embolism, 226 (98.7%) had no evidence of acute pulmonary embolism or deep venous thrombosis. The negative predictive value of a negative d-dimer result was therefore 98.7% (confidence interval, 96.2%–99.7%). Conclusion The d-dimer assay is a simple rapid blood test that is sensitive to the presence of acute thrombosis. Very few patients with negative results have acute deep venous thrombosis or pulmonary embolism, with combined CT venography and pulmonary angiography used as the reference standard.