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.

Transcranial ultrasound in clinical sonothrombolysis (TUCSON) trial.

OBJECTIVE: Microspheres (microS) reach intracranial occlusions and transmit energy momentum from an ultrasound wave to residual flow to promote recanalization. We report a randomized multicenter phase II trial of microS dose escalation with systemic thrombolysis. METHODS: Stroke patients receiving 0.9mg/kg tissue plasminogen activator (tPA) with pretreatment proximal intracranial occlusions on transcranial Doppler (TCD) were randomized (2:1 ratio) to microS (MRX-801) infusion over 90 minutes (Cohort 1, 1.4ml; Cohort 2, 2.8ml) with continuous TCD insonation, whereas controls received tPA and brief TCD assessments. The primary endpoint was symptomatic intracerebral hemorrhage (sICH) within 36 hours after tPA. RESULTS: Among 35 patients (Cohort 1 = 12, Cohort 2 = 11, controls = 12) no sICH occurred in Cohort 1 and controls, whereas 3 (27%, 2 fatal) sICHs occurred in Cohort 2 (p = 0.028). Sustained complete recanalization/clinical recovery rates (end of TCD monitoring/3 month) were 67%/75% for Cohort 1, 46%/50% for Cohort 2, and 33%/36% for controls (p = 0.255/0.167). The median time to any recanalization tended to be shorter in Cohort 1 (30 min; interquartile range [IQR], 6) and Cohort 2 (30 min; IQR, 69) compared to controls (60 min; IQR, 5; p = 0.054). Although patients with sICH had similar screening and pretreatment systolic blood pressure (SBP) levels in comparison to the rest, higher SBP levels were documented in sICH+ patients at 30 minutes, 60 minutes, 90 minutes, and 24-36 hours following tPA bolus. INTERPRETATION: Perflutren lipid microS can be safely combined with systemic tPA and ultrasound at a dose of 1.4ml. Safety concerns in the second dose tier may necessitate extended enrollment and further experiments to determine the mechanisms by which microspheres interact with tissues. In both dose tiers, sonothrombolysis with microS and tPA shows a trend toward higher early recanalization and clinical recovery rates compared to standard intravenous tPA therapy. Ann Neurol 2009;66:28-38.

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.

Emergency medicine resident performed bedside ultrasonography of the gallbladder in non-fasted healthy volunteers.

BACKGROUND: Gallbladder ultrasonography is a commonly performed test in the emergency department. It is unknown whether a non-fasting state alters the visualization of the gallbladder by emergency medicine (EM) residents. OBJECTIVES: We conducted this study to determine whether EM residents are able to visualize the gallbladder in volunteers who have recently consumed a fatty meal. METHODS: This study used a prospective, single-blinded, randomized controlled design. Initial scans were performed on fasting volunteers. A fatty meal was then consumed. Thirty minutes after eating, a different resident, who was unaware of whether the volunteer had eaten or fasted, performed a second scan. To control for operator bias, 10% of subjects remained fasting between scans. Student's paired-samples t-test, Pearson's chi-squared, and McNemar test were determined as appropriate. RESULTS: A total of 92 scans from 46 volunteers were analyzed. EM residents were able to visualize the gallbladder in all 40 pre-prandial scans (100%) and all 40 post-prandial scans (100%). Gallbladder area as measured in the longitudinal axis decreased 20% from a mean baseline of 11.58 +/- 4.86 cm(2) (95% confidence interval [CI] 11.17-12.98) to 9.2 +/- 5.04 cm(2) (95% CI 7.74-10.66, p = 0.0009) after food intake. Total time to scan for the fasting volunteers (110.2 s, 95% CI 84.34-136) did not change significantly from non-fasting volunteers (129.7 s, 95% CI 110.29-149.01, p = 0.153). CONCLUSIONS: EM residents are able to visualize the gallbladder in non-fasted healthy volunteers.

Unilateral papilledema: a case of optic neuritis diagnosed with bedside ocular sonography.

Optic neuritis is a demyelinating inflammatory condition that causes acute loss of vision, especially color vision, and eye pain. Magnetic resonance imaging and fundoscopy have traditionally aided the diagnosis of what largely remains a clinical diagnosis. We report a case of optic neuritis diagnosed in the emergency department with the aid of bedside ocular sonography. The pathophysiology, diagnosis and management of acute optic neuritis will be reviewed.

A pilot randomized clinical safety study of sonothrombolysis augmentation with ultrasound-activated perflutren-lipid microspheres for acute ischemic stroke.

BACKGROUND AND PURPOSE: Ultrasound transiently expands perflutren-lipid microspheres (muS), transmitting energy momentum to surrounding fluids. We report a pilot safety/feasibility study of ultrasound-activated muS with systemic tissue plasminogen activator (tPA). METHODS: Stroke subjects treated within 3 hours had abnormal Thrombolysis in Brain Ischemia (TIBI) residual flow grades 0 to 3 before tPA on transcranial Doppler (TCD). Randomization included Controls (tPA+TCD) or Target (tPA+TCD+2.8 mL microS). The primary safety end point was symptomatic intracranial hemorrhage (sICH) with worsening by >or=4 NIHSS points within 72 hours. RESULTS: Fifteen subjects were randomized 3:1 to Target, n=12 or Control, n=3. After treatment, asymptomatic ICH occurred in 3 Target and 1 Control, and sICH was not seen in any study subject. muS reached MCA occlusions in all Target subjects at velocities higher than surrounding residual red blood cell flow: 39.8+/-11.3 vs 28.8+/-13.8 cm/s, P<0.001. In 75% of subjects, microS permeated to areas with no pretreatment residual flow, and in 83% residual flow velocity improved at a median of 30 minutes from start of microS infusion (range 30 s to 120 minutes) by a median of 17 cm/s (118% above pretreatment values). To provide perspective, current study recanalization rates were compared with the tPA control arm of the CLOTBUST trial: complete recanalization 50% versus 18%, partial 33% versus 33%, none 17% versus 49%, P=0.028. At 2 hours, sustained complete recanalization was 42% versus 13%, P=0.003, and NIHSS scores 0 to 3 were reached by 17% versus 8%, P=0.456. CONCLUSIONS: Perflutren microS reached and permeated beyond intracranial occlusions with no increase in sICH after systemic thrombolysis suggesting feasibility of further microS dose-escalation studies and development of drug delivery to tissues with compromised perfusion.

Ultrasound diagnosis of quadriceps tendon rupture.

Quadriceps tendon ruptures are an uncommon knee injury. The diagnosis is often complicated by a limited examination secondary to edema and pain, the insensitivity of radiographs, and the unavailability of non-emergent magnetic resonance imaging. A delay in diagnosis and treatment has been shown to cause significant morbidity. A case report of bilateral quadriceps tendon rupture is presented demonstrating the utility and ease of bedside ultrasound to rapidly confirm the diagnosis.

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.

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.

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.

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.