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Thứ Sáu, 30 tháng 5, 2014

J U M 6-2014

  1. Abstract 1
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  5. Abstract 5
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  1. Abstract 1 of 6Original Research

    The Sonographic “Bright Band Sign” of Splenic Infarction

    Objectives—To evaluate the frequency of the “bright band sign” in patients with splenic infarcts as well as control patients and to thereby assess whether the bright band sign has potential utility as a sonographic sign of splenic infarction.
    Methods—Using an electronic search engine and image review, 37 patients were retrospectively identified with noncystic parenchymal splenic infarcts on sonography. Nineteen abnormal control patients with noninfarcted splenic lesions on sonography and 100 normal control patients with sonographically normal spleens were also identified. The sonographic appearance of each splenic lesion was evaluated by 2 reviewers and assessed for the bright band sign, defined as thin specular reflectors perpendicular to the sound beam within hypoechoic parenchymal lesions, and for the presence or absence of the classic sonographic appearance of splenic infarction. Possible histologic counterparts of the bright band sign were assessed in archival infarct specimens.
    Results—The bright band sign was present in 34 (91.9%; 95% confidence interval [CI], 78.1%–98.3%) of 37 patients with splenic infarcts on sonography, including 12 (85.7%; 95% CI, 57.2%–98.2%) of 14 with classic and 22 (95.7%; 95% CI, 78.1%–99.9%) of 23 with nonclassic infarct appearances. No normal or abnormal control patients had the bright band sign. Histologic sections suggested that preserved splenic trabeculae within infarcts may generate the bright band sign.
    Conclusions—The bright band sign is a potentially useful sonographic sign of splenic infarction, which may confer additional sensitivity and specificity and may be particularly helpful with infarcts having nonclassic appearances.
    • Received July 8, 2013.
    • Revision received July 31, 2013.
    • Accepted September 23, 2013.
  2. Abstract 2 of 6Original Research

    Exploring Carotid Sonographic Parameters Associated With Stroke Risk Among Hypertensive Stroke Patients Compared to Hypertensive Controls

    Objectives—Globally, and particularly in low- and middle-income countries, the prevalence of hypertension is increasing with a consequent rise in the burden of stroke. There is a need to identify biomarkers of stroke, which can be used to design stroke prevention programs in these populations. Sonography is an affordable and widely available imaging modality that is ideal for resource-poor countries. We conducted a case-control study to identify carotid sonographic parameters that may be associated with stroke risk among hypertensive patients.
    Methods—Selected demographic, clinical, and laboratory characteristics were collected from 135 consecutive African hypertensive stroke patients and compared with 117 age and sex-matched hypertensive patients with no clinical evidence of stroke, transient ischemic attacks, or ischemic heart disease (controls). The luminal diameter, intima-media thickness, peak systolic velocity (PSV), and end-diastolic velocity (EDV) of the common and internal carotid arteries were measured in all participants, and other carotid parameters, including pulsatility and resistive indices, were derived. Univariate, bivariate, and multivariate analyses were performed
    Results—Among hypertensive patients, carotid parameters significantly (P < .05) associated with stroke included a higher diameter and intima-media thickness as well as a lower PSV and EDV in the common carotid and proximal internal carotid arteries. However, the diameter (>6.3 mm; adjusted odds ratio [OR], 8.91; 95% confidence interval [CI], 2.18–36.34; P= .002) and EDV (>21 cm/s; adjusted OR, 0.15; 95% CI, 0.03–0.71; P = .017) of the common carotid artery were the only parameters associated with stroke in multivariate analysis.
    Conclusions—Among hypertensive patients, the common carotid artery diameter and EDV are significantly associated with stroke risk. These findings have implications for development and evaluation of stroke prevention programs.
    • Received July 23, 2013.
    • Revision received September 4, 2013.
    • Accepted October 10, 2013.
  3. Abstract 3 of 6Original Research

    Quality Assurance in Ultrasound Screening for Hepatocellular Carcinoma Using a Standardized Phantom and Standard Clinical Images

    A 3-Year National Investigation in Korea

    Objectives—The purpose of this study was to investigate the quality of ultrasound (US) imaging for hepatocellular carcinoma screening.
    Methods—The investigation was performed at all medical institutes participating in the National Cancer Screening Program in Korea. For assessment of personnel, we inquired who was performing the US screenings. For phantom image evaluation, the dead zone, vertical and horizontal measurements, axial and lateral resolution, sensitivity, and gray scale/dynamic range were evaluated. For clinical image evaluation, US images of patients were evaluated in terms of the standard images, technical information, overall image quality, appropriateness of depth, foci, annotations, and the presence of any artifacts.
    Results—Failure rates for phantom and clinical image evaluations at general hospitals, smaller hospitals, and private clinics were 20.9%, 24.5%, 24.1% and 5.5%, and 14.8% and 9.5%, respectively. No statistically significant difference was observed in the failure rates for the phantom images among groups of different years of manufacture. For the clinical image evaluation, the results of radiologists were significantly better than those of other professional groups (P = .0001 and .0004 versus nonradiology physicians and nonphysicians, respectively). The failure rate was also higher when the storage format was analog versus digital (P < .001).
    Conclusions—Approximately 20% of US scanners failed the phantom image evaluation. The year of scanner manufacture was not significantly associated with the results of the phantom image evaluation. The quality of the clinical images obtained by radiologists was the best.
    • Received July 9, 2013.
    • Revision received August 21, 2013.
    • Accepted October 16, 2013.
  4. Abstract 4 of 6Original Research

    Do Emergency Ultrasound Fellowship Programs Impact Emergency Medicine Residents’ Ultrasound Education?

    Objectives—Recent years have seen a rapid proliferation of emergency ultrasound (EUS) programs in the United States. To date, there is no evidence supporting that EUS fellowships enhance residents’ ultrasound (US) educational experiences. The purpose of this study was to determine the impact of EUS fellowships on emergency medicine (EM) residents’ US education.
    Methods—We conducted a cross-sectional study at 9 academic medical centers. A questionnaire on US education and bedside US use was pilot tested and given to EM residents. The primary outcomes included the number of US examinations performed, scope of bedside US applications, barriers to residents’ US education, and US use in the emergency department. The secondary outcomes were factors that would impact residents’ US education. The outcomes were compared between residency programs with and without EUS fellowships.
    Results—A total of 244 EM residents participated in this study. Thirty percent (95% confidence interval, 24%–35%) reported they had performed more than 150 scans. Residents in programs with EUS fellowships reported performing more scans than those in programs without fellowships (P = .04). Significant differences were noted in most applications of bedside US between residency programs with and without fellowships (P < .05). There were also significant differences in the barriers to US education between residency programs with and without fellowships (P < .05).
    Conclusions—Emergency US fellowship programs had a positive impact on residents’ US educational experiences. Emergency medicine residents performed more scans overall and also used bedside US for more advanced applications in programs with EUS fellowships.
    • Received July 26, 2013.
    • Revision received September 10, 2013.
    • Accepted October 1, 2013.
  5. Abstract 5 of 6Original Research

    Ultrasound for Internal Medicine Physicians

    The Future of the Physical Examination

    Objectives—With the advent of compact ultrasound (US) devices, it is easier for physicians to enhance their physical examinations through the use of US. However, although this new tool is widely available, few internal medicine physicians have US training. This study sought to understand physicians’ baseline knowledge and skill, provide education in US principles, and demonstrate that proper use of compact US devices is a skill that can be quickly learned.
    Methods—Training was performed at the Mayo Clinic in June 2010 and June 2011. The participants consisted of internal medicine residents. The workshop included didactics and hands-on US experiences with human and cadaver models in a simulation center. Pretests and posttests of residents’ knowledge, attitudes, and skills with US were completed. We reassessed the 2010 group in the spring of 2012 with a long-term retention survey for knowledge and confidence in viewing images.
    Results—A total of 136 interns completed the workshop. Thirty-nine residents completed the long-term retention survey. Posttest assessments showed a statistically significant improvement in the knowledge of US imaging, confidence in identifying structures, image identification, and image acquisition (P < .0001). In the long-term retention study, knowledge of US imaging and confidence in identifying structures did decline.
    Conclusions—This educational intervention resulted in improvement in US knowledge and image acquisition. However, the knowledge diminished over time, suggesting that further education is needed if US is to become an important component of internal medicine training and practice.
    • Received July 29, 2013.
    • Revision received August 15, 2013.
    • Accepted October 2, 2013.
  6. Abstract 6 of 6Original Research

    Acoustic Radiation Force Impulse Imaging for Evaluation of the Thyroid Gland

    Objectives—To study acoustic radiation force impulse (ARFI) imaging as a new quantitative and noninvasive tool for evaluating thyroid nodules and to compare ARFI imaging with other tools for studying thyroid nodules: sonography, real-time elastography, and fine-needle aspiration biopsy.
    Methods—We conducted a prospective study from June 2011 to June 2012, which analyzed 157 thyroid nodules (129 benign and 28 malignant) using the ARFI technique and a 9-MHz probe. Shear wave velocities (SWVs) were obtained while the patients held their breath to avoid respiratory movement artifacts. All nodules underwent conventional sonography and real-time elastography of the thyroid gland. All patients received either a cytologic examination using fine-needle aspiration biopsy or a histologic examination from thyroid surgery to verify the diagnosis (reference standard).
    Results—The mean SWV ± SD on ARFI imaging in healthy, nodule-free thyroid glands was 2.04 ± 0.51 m/s (range, 0.76–3.63 m/s). The mean SWV in benign thyroid nodules was 1.70 ± 0.55 m/s (range, 0.50–2.80 m/s), and the mean SWV in malignant nodules was 3.39 ± 1.15 m/s (range, 1.50–6.08 m/s). When we used an SWV greater than 2.50 m/s for the diagnosis of malignant nodules and less than 2.50 m/s for the diagnosis of benign nodules, the sensitivity and specificity of ARFI imaging were 85.7% and 96.0%, respectively.
    Conclusions—We found that SWVs were substantially higher in malignant nodules than benign ones. Perhaps if ARFI imaging is used in conjunction with sonographic findings and patient demographics, it will be possible to find a combination of factors that would yield a negative predictive value high enough to distinguish benign from malignant nodules with confidence, which may lead to a decrease in the biopsy rate for benign nodules.
    • Received March 26, 2013.
    • Revision received May 1, 2013.
    • Accepted September 30, 2013.

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