Applications of justification and optimization in medical imaging: examples of clinical guidance for computed tomography use in emergency medicine.

Availability, reliability, and technical improvements have led to continued expansion of computed tomography (CT) imaging. During a CT scan, there is substantially more exposure to ionizing radiation than with conventional radiography. This has led to questions and critical conclusions about whether the continuous growth of CT scans should be subjected to review and potentially restraints or, at a minimum, closer investigation. This is particularly pertinent to populations in emergency departments, such as children and patients who receive repeated CT scans for benign diagnoses. During the last several decades, among national medical specialty organizations, the American College of Emergency Physicians and the American College of Radiology have each formed membership working groups to consider value, access, and expedience and to promote broad acceptance of CT protocols and procedures within their disciplines. Those efforts have had positive effects on the use criteria for CT by other physician groups, health insurance carriers, regulators, and legislators.

Ultrasound-guidance can reduce adverse events during femoral central venous cannulation.

BACKGROUND: Ultrasound-guidance for internal jugular central venous cannulation (CVC) has become the recommended best practice and has been shown to improve placement success and reduce complications. There is a dearth of studies that evaluate emergency point-of-care ultrasound guidance of femoral CVC. OBJECTIVE: Our aim was to determine if point-of-care ultrasound guidance for femoral CVC decreases adverse events and increases the likelihood of successful placement when compared with the landmark technique. METHODS: We conducted an Institutional Review Board-approved, prospective, observational study of consecutive patients who required CVC. Physicians who performed CVC completed a standardized, web-based data sheet for a national CVC registry. We evaluated single-institution data regarding CVC site, ultrasound usage, CVC indication, and mechanical complications (e.g., pneumothorax, arterial puncture, failed access, catheter misdirection, and hematoma). The study period was between January 2006 and June 2010. Analysis using Pearson's χ(2) and Agresti-Coull binomial confidence intervals was performed; significance was defined as p < 0.05. RESULTS: We evaluated data for 143 patients who had femoral CVC in our institution. Sixty CVCs (42%) were performed under ultrasound guidance, 83 (58%) via landmark technique (p = 0.0159); 3.3% of femoral central venous lines placed by ultrasound guidance had recorded adverse events compared with 9.6% for the landmark technique (p = 0.145). There was no statistically significant difference in complications between ultrasound-guidance and landmark techniques. Our data showed a trend toward decreased rates of arterial puncture and reduced cannulation attempts resulting in improved placement success. CONCLUSIONS: Our experience shows that ultrasound guidance for femoral CVC might decrease complications and improve placement success, although we cannot recommend this approach without additional data. We recommend a larger study to further evaluate this technique.

Assessment of Medicare's imaging efficiency measure for emergency department patients with atraumatic headache.

STUDY OBJECTIVE: Computed tomography (CT) use has increased rapidly, raising concerns about radiation exposure and cost. The Centers for Medicare & Medicaid Services (CMS) developed an imaging efficiency measure (Outpatient Measure 15 [OP-15]) to evaluate the use of brain CT in the emergency department (ED) for atraumatic headache. We aim to determine the reliability, validity, and accuracy of OP-15. METHODS: This was a retrospective record review at 21 US EDs. We identified 769 patient visits that CMS labeled as including an inappropriate brain CT to identify clinical indications for CT and reviewed the 748 visits with available records. The primary outcome was the reliability of OP-15 as determined by CMS from administrative data compared with medical record review. Secondary outcomes were the measure's validity and accuracy. Outcome measures were defined according to the testing protocol of the American Medical Association's Physician Consortium for Performance Improvement. RESULTS: On record review, 489 of 748 ED brain CTs identified as inappropriate by CMS had a measure exclusion documented that was not identified by administrative data; the measure was 34.6% reliable (95% confidence interval [CI] 31.2% to 38.0%). Among the 259 patient visits without measure exclusions documented in the record, the measure's validity was 47.5% (95% CI 41.4% to 53.6%), according to a consensus list of indications for brain CT. Overall, 623 of the 748 ED visits had either a measure exclusion or a consensus indication for CT; the measure's accuracy was 16.7% (95% CI 14% to 19.4%). Hospital performance as reported by CMS did not correlate with the proportion of CTs with a documented clinical indication (r=-0.11; P=.63). CONCLUSION: The CMS imaging efficiency measure for brain CTs (OP-15) is not reliable, valid, or accurate and may produce misleading information about hospital ED performance.

The double-line sign: a false positive finding on the Focused Assessment with Sonography for Trauma (FAST) examination.

BACKGROUND: Emergency physicians commonly perform Focused Assessment with Sonography for Trauma (FAST) examinations to evaluate for free intraperitoneal fluid. Many ultrasound findings can be misinterpreted as free fluid, resulting in false-positive FAST examinations. OBJECTIVES: To describe a previously unreported ultrasound finding that can be misinterpreted as free intraperitoneal fluid. CASE REPORT: A 32-year-old man was stabbed in the left upper abdomen. A FAST examination was performed and a right perinephric fat pad was interpreted as showing free fluid in Morison's pouch. After transfer to a trauma center, a repeat FAST examination revealed no signs of intraperitoneal free fluid. Wound exploration showed no signs of penetration into the peritoneal cavity. CONCLUSIONS: When performing a FAST examination, a wedge-shaped hypoechoic area in Morison's pouch that is bounded on both sides by echogenic lines (the "FAST Double-Line Sign") is likely to represent perinephric fat and may result in a false-positive FAST examination.

Ultrasound diagnosis of penile fracture.

BACKGROUND: Rupture of the corpus cavernosum, penile fracture, is an uncommon occurrence. Diagnosis is straightforward when classical historical and physical examination findings are present. However, atypical presentations can make the diagnosis difficult. OBJECTIVES: Review the literature supporting use of ultrasound for the diagnosis of penile fracture. Review of the ultrasonographic findings in patients with penile fracture. CASE REPORT: A 32-year-old man presented with penile ecchymosis after sex but lacking several historical and physical examination elements for a diagnosis of penile fracture. Ultrasound performed by the treating physician revealed rupture of the tunica albuginea and presence of a hematoma, leading to a diagnosis of penile fracture. CONCLUSION: Ultrasound is a simple, efficient, and non-invasive imaging method to assist in the diagnosis of penile fracture.

Cross sectional survey of ultrasound use for central venous catheter insertion among resident physicians.

BACKGROUND: Use of ultrasound guidance for Central Venous Catheter insertion has been associated with decreased complications and increased success rates. Previous reports show low rates of use among physicians. OBJECTIVES: Evaluation of the frequency of Ultrasound Guidance use for Central Venous Catheter insertion among residents at a teaching institution. METHODS: A cross sectional electronic survey of resident physicians at a tertiary care teaching hospital was conducted to evaluate use of Ultrasound Guidance for Central Venous Catheterization. Assessment included self reported frequency of ultrasound guidance use, and volume of central venous catheter placement. Attitudes toward the use of ultrasound were assessed using Likert scales. RESULTS: There is a high rate. over 90%, of ultrasound guidance use for Internal Jugular central venous catheters among residents. The majority of residents use sterile real-time imaging with a single operator with a reported success rate greater then 80%. CONCLUSIONS: Resident use of ultrasound guidance for Internal Jugular central venous catheter insertion can be much higher than previously reported in the literature.

Impending cardiac tamponade: a case report highlighting the value of bedside echocardiography.

Cardiac tamponade is a life-threatening process that must be diagnosed and treated in a timely fashion. As blood fills the pericardial sac, right ventricular filling is impeded and cardiac output is diminished, ultimately leading to cardiovascular collapse. Fortunately, emergency ultrasonography has improved the way we manage these patients today. In this report, we discuss a patient with hypotension and tachycardia who was found to have a massive loculated posterior pericardial effusion with impending cardiac tamponade. The diagnosis and appropriate treatment of this patient were rapidly ascertained with the use of bedside echocardiography. We review the literature on emergency ultrasonography, and consider the numerous instances in which emergency echocardiography can be life-saving.

Elevated intracranial pressure detected by bedside emergency ultrasonography of the optic nerve sheath.

UNLABELLED: Patients with altered level of consciousness may be suffering from elevated intracranial pressure (EICP) from a variety of causes. A rapid, portable, and noninvasive means of detecting EICP is desirable when conventional imaging methods are unavailable. OBJECTIVES: The hypothesis of this study was that ultrasound (US) measurement of the optic nerve sheath diameter (ONSD) could accurately predict the presence of EICP. METHODS: The authors performed a prospective, blinded observational study on emergency department (ED) patients with a suspicion of EICP due to possible focal intracranial pathology. The study was conducted at a large community ED with an emergency medicine residency program and took place over a six-month period. Patients suspected of having EICP by an ED attending were enrolled when study physicians were available. Unstable patients were excluded. ONSD was measured 3 mm behind the globe using a 10-MHz linear probe on the closed eyelids of supine patients, bilaterally. Based on prior literature, an ONSD above 5 mm on ultrasound was considered abnormal. Computed tomography (CT) findings defined as indicative of EICP were the presence of mass effect with a midline shift 3 mm or more, a collapsed third ventricle, hydrocephalus, the effacement of sulci with evidence of significant edema, and abnormal mesencephalic cisterns. For each patient, the average of the two ONSD measurements was calculated and his or her head CT scans were evaluated for signs of EICP. Student's t-test was used to compare ONSDs in the normal and EICP groups. Sensitivity, specificity, and positive and negative predictive values were calculated. RESULTS: Thirty-five patients were enrolled; 14 had CT results consistent with EICP. All cases of CT-determined EICP were correctly predicted by ONSD over 5 mm on US. One patient with ONSD of 5.7 mm in one eye and 3.7 mm in the other on US had a mass abutting the ipsilateral optic nerve; no shift was seen on CT. He was placed in the EICP category on his data collection sheet. The mean ONSD for the 14 patients with CT evidence of EICP was 6.27 mm (95% CI = 5.6 to 6.89); the mean ONSD for the others was 4.42 mm (95% CI = 4.15 to 4.72). The difference of 1.85 mm (95% CI = 1.23 to 2.39 mm) yielded a p = 0.001. The sensitivity and specificity for ONSD, when compared with CT results, were 100% and 95%, respectively. The positive and negative predictive values were 93% and 100%, respectively. CONCLUSIONS: Despite small numbers and selection bias, this study suggests that bedside ED US may be useful in the diagnosis of EICP.

A study of bedside ocular ultrasonography in the emergency department.

UNLABELLED: The use of ocular ultrasonography for the evaluation of emergency patients has recently been described in the emergency medicine (EM) literature. There are a number of potential uses that may greatly aid the emergency physician (EP) and avoid lengthy consultation or other diagnostic tests. OBJECTIVE: To examine the accuracy of bedside ultrasonography as performed by EPs for the evaluation of ocular pathology. METHODS: This prospective, observational study took place in a high-volume, suburban community hospital with an EM residency program. All patients arriving with a history of eye trauma or acute change in vision were eligible to participate in the study. A 10-MHz linear-array transducer was used for imaging. All imaging was performed through a closed eyelid, using water-soluble ultrasound gel. Investigators filled out standardized data sheets and all examinations were taped for review. All ultrasound examinations were followed by orbital computed tomography or complete ophthalmologic evaluation from the ophthalmology service. Statistical analysis included sensitivity, specificity, and positive and negative predictive values. RESULTS: Sixty-one patients were enrolled in the study; 26 were found to have intraocular pathology on ultrasound. Of these, three had penetrating globe injuries, nine had retinal detachments, one had central retinal artery occlusion, and two had lens dislocations. The remaining pathology included vitreous hemorrhage and vitreous detachment. Emergency sonologists were in agreement with the criterion standard examination in 60 out of 61 cases. CONCLUSIONS: Emergency bedside ultrasound is highly accurate for ruling out and diagnosing ocular pathology in patients presenting to the emergency department. Further, it accurately differentiates between pathology that needs immediate ophthalmologic consultation and that which can be followed up on an outpatient basis.

Tissue harmonic imaging improves organ visualization in trauma ultrasound when compared with standard ultrasound mode.

UNLABELLED: The focused abdominal sonography for trauma (FAST) examination is complicated by brightly lit trauma bays, limited time, and body habitus. Recently, new ultrasound (US) technology has become available that improves organ visualization in abdominal scans. OBJECTIVE: The hypothesis was that a new US mode, tissue harmonic (TH) imaging, improves visualization of critical organ relationships in the FAST examination by making use of previously unused frequencies. The authors performed a blind, prospective observational study to compare the images obtained in typical FAST views with those obtained in standard US and TH modes. METHODS: Blunt trauma patients presenting to a level I trauma center between April and September 2000 were enrolled on a convenience basis. Typical FAST views were obtained in standard and TH modes. The emergency ultrasonographer (EU) switched between modes for each view, optimizing the gain each time. Multiple digital still images were made with all indications of the mode used disguised. For each view on a patient, the best image in each mode was selected in a blinded fashion. Three experienced EUs, blinded to the mode used, rated each image pair for resolution, detail, and total image quality as previously defined on a ten-point Likert scale, 10 being the best for each category. Wilcoxon signed-ranks test, 95% confidence intervals (95% CIs), and interobserver correlation were calculated. RESULTS: A total of 76 image groups (39 of Morison's pouch, 20 splenorenal, and 17 bladder) from 52 patients were rated. Tissue harmonics produced improved resolution, detail, and quality when compared with the standard US mode, with median scores of 6.7 vs. 6.0, 6.7 vs. 6.0, and 6.3 vs. 6.0, respectively. The differences of 0.7 (95% CI = 0.4 to 0.93), 0.7 (95% CI = 0.4 to 0.93), and 0.33 (95% CI = 0.17 to 0.67) were statistically significant, with p = 0.0001, 0.0001, and 0.0003, respectively. There was good interobserver agreement (kappa = 0.74; 95% CI = 0.68 to 0.79). CONCLUSIONS: Tissue harmonics produced FAST images higher in detail, resolution, and total image quality than standard-mode US images.

Applications of justification and optimization in medical imaging: examples of clinical guidance for computed tomography use in emergency medicine.

Availability, reliability, and technical improvements have led to continued expansion of computed tomography (CT) imaging. During a CT scan, there is substantially more exposure to ionizing radiation than with conventional radiography. This has led to questions and critical conclusions about whether the continuous growth of CT scans should be subjected to review and potentially restraints or, at a minimum, closer investigation. This is particularly pertinent to populations in emergency departments, such as children and patients who receive repeated CT scans for benign diagnoses. During the last several decades, among national medical specialty organizations, the American College of Emergency Physicians and the American College of Radiology have each formed membership working groups to consider value, access, and expedience and to promote broad acceptance of CT protocols and procedures within their disciplines. Those efforts have had positive effects on the use criteria for CT by other physician groups, health insurance carriers, regulators, and legislators.

ACR Appropriateness Criteria head trauma--child.

Head trauma is a frequent indication for cranial imaging in children. CT is considered the first line of study for suspected intracranial injury because of its wide availability and rapid detection of acute hemorrhage. However, the majority of childhood head injuries occur without neurologic complications, and particular consideration should be given to the greater risks of ionizing radiation in young patients in the decision to use CT for those with mild head trauma. MRI can detect traumatic complications without radiation, but often requires sedation in children, owing to the examination length and motion sensitivity, which limits rapid assessment and exposes the patient to potential anesthesia risks. MRI may be helpful in patients with suspected nonaccidental trauma, with which axonal shear injury and ischemia are more common and documentation is critical, as well as in those whose clinical status is discordant with CT findings. Advanced techniques, such as diffusion tensor imaging, may identify changes occult by standard imaging, but data are currently insufficient to support routine clinical use. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 3 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Prospective durability testing of a vascular access phantom.

INTRODUCTION: We assessed the acoustic transmission, image quality, and vessel integrity of the Blue Phantom™ 2 Vessel Original Ultrasound Training Model with repeated use. METHODS: The study consisted of two phases. During the first phase, a portion of the Blue Phantom™ rubber matrix (without a simulated vessel) was placed over a two-tiered echogenic structure and was repeatedly punctured with a hollow bore 18-gauge needle in a 1 cm(2) area. During the second phase, a portion of the matrix with a simulated vessel was repeatedly punctured with another hollow bore 18-gauge needle. During both phases we obtained an ultrasound image using a high-frequency linear probe after every 100 needle punctures to assess the effect of repeated needle punctures on image quality, acoustic transmission, and simulated vessel integrity. RESULTS: Testing on the rubber matrix alone (first phase) without a vessel demonstrated a gradual decrease in image quality and visualization of the proximal and distal portions of the target structure, but they remained visible after 1,000 needle punctures. The second phase demonstrated excellent acoustic transmission and image quality on both transverse and longitudinal images of the rubber matrix and simulated vessel after 1,000 needle punctures. The anterior and posterior vessel walls and needle tip were well visualized without any signs of vessel leakage on still images or with compression and power Doppler. CONCLUSION: The Blue Phantom™ 2 Vessel Original Ultrasound Training Model demonstrated excellent durability after 1,000 needle punctures in a 1- cm(2) area. Based on the length of simulated vessel in each model, it should support over 25,000 simulated attempts at vascular access.

Does the simple triage and rapid treatment method appropriately triage patients based on trauma injury severity score?

OBJECTIVES: To correlate the simple triage and rapid treatment (START) colors to trauma injury severity scores (ISS). DESIGN: Six volunteer healthcare providers unfamiliar with START were trained to triage. Each chart was designated a START color by a volunteer healthcare provider and the "expert" trainer. The colors and corresponding ISS were recorded. SETTING: Level I trauma center at a suburban tertiary care hospital. PATIENTS, PARTICIPANTS: One hundred charts of patients at least 65 years old who appear in Christiana Hospital's Trauma Registry were randomly chosen for the study, and 98 charts with complete data were included. MAIN OUTCOME MEASURE(S): Cohen's Kappa score measures the level of agreement between the "volunteer" and "expert" reviewers. Pearson correlation determines the association between the START colors and mean ISS. RESULTS: The Cohen's Kappa score between the volunteer and expert reviewers was 0.9915, indicating a highly significant agreement between the reviewers on the triage category of the patients. The mean ISS for each color was as follows: green = 11, yellow = 12, red = 20, black = 24. The mean ISS increases as the acuity of the triage category increases, with a Pearson correlation of 0.969. CONCLUSIONS: The START method is a simple technique used to triage quickly a large number of patients. Healthcare providers can undergo just-in-time training to learn this technique and use it effectively. The START colors also imply a correlation with the trauma ISS, with higher ISS more likely to be triaged "red" or "black."

A randomized controlled trial of ultrasound-assisted lumbar puncture.

OBJECTIVE: Evidence showing the systematic utility of ultrasound imaging during lumbar puncture (LP) in the emergency department is lacking. Our hypothesis was that ultrasound-assisted LP would increase the success rate and ease of performing LP with a greater benefit in obese patients. METHODS: This was an Institutional Review Board-approved, randomized, prospective, double-blind study conducted at the emergency department of a teaching institution. Patients undergoing LP from January to December 2004 were eligible for enrollment. Patients were randomized to undergo LP using palpation landmarks (PLs) or ultrasound landmarks (ULs). Data collected included age, body mass index, number of attempts, ease of performance and patient comfort on a 10-cm Visual Analog Scale, procedure time, success, and traumatic LP. Statistical analysis of data included relative risk (RR), the Mann-Whitney U test, and the Student t test. RESULTS: A total of 46 patients were enrolled, 22 randomized to PLs and 24 to ULs. There were no differences between the groups in mean age or body mass index. Six of 22 attempts failed with PLs versus 1 of 24 with ULs (RR, 1.32; 95% confidence interval, 1.01-1.72). In 12 obese patients, 4 of 7 PL attempts failed versus 0 of 5 UL attempts (RR, 2.33; 95% confidence interval, 0.99-5.49). The ease of the procedure was better with ULs versus PLs. There were no statistical differences in the number of attempts, traumatic LPs, patient comfort, or procedure length. CONCLUSIONS: The use of ultrasound for LP significantly reduced the number of failures in all patients and improved the ease of the procedure in obese patients.

Dissection of the proximal thoracic aorta: a new ultrasonographic sign in the subxiphoid view.

Dissection of the thoracic aorta is a life-threatening event that presents with some regularity to emergency departments (EDs). Despite often nonspecific symptoms, it is critical to catch this disease process early, especially when the proximal aorta is involved because dissections involving the aortic root can lead to myocardial infarction and failure of the aortic valve resulting in death. Current imaging options include contrast-enhanced chest computed tomography (CT), angiography, magnetic resonance imaging, or transesophageal echocardiography. Although not as accurate as transesophageal echocardiography, transthoracic echocardiography (TTE) can be used to detect aortic dissection as well. We present a previously undescribed echocardiographic finding associated with proximal dissection of the thoracic aorta in 7 cases.