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Thứ Sáu, 30 tháng 10, 2015

J U M 11-2015

Selected Abstracts
1.       Abstract 1 of 7Original Research
Combined Use of Ultrasound Elastography and B-Mode Sonography for Differentiation of Benign and Malignant Circumscribed Breast Masses
Objectives—To evaluate the diagnostic performance of combined B-mode sonography and ultrasound elastography for differentiation between benign and malignant breast masses with circumscribed margins.
Methods—We analyzed 109 pathologically proven circumscribed breast masses. Two radiologists retrospectively reviewed B-mode sonograms and elastograms in consensus. Based on the American College of Radiology Breast Imaging Reporting and Data System, we determined categories of the masses on B-mode sonography. Elastographic scores were assessed by a 3-point scale (negative, 0; equivocal, 1; and positive, 2). When the elastographic score for a lesion was 0 or 2, we downgraded or upgraded the B-mode category, respectively; thus, the reclassified Breast Imaging Reporting and Data System category was defined as the “reclassification category.” Mean category values for benign and malignant lesions were compared by a Student t test. The diagnostic performance of B-mode, elastographic, and reclassification assessments was compared by receiver operating characteristic curve analysis.
Results—The mean B-mode category (2.5 versus 1.7), elastographic score (1.7 versus 0.8), and reclassification category (3.2 versus 1.6) were significantly higher in malignant than benign lesions (P < .001). The area under the curve for reclassification assessment was significantly higher than that for B-mode sonography (0.916 versus 0.795; P < .05). With a cutoff value between 1 and 2, the specificity was increased from 26.5% to 42.9% after reclassification.
Conclusions—For differentiation between benign and malignant circumscribed breast masses, combined use of B-mode sonography and elastography could provide a better diagnostic performance than B-mode sonography alone.
o    © 2015 by the American Institute of Ultrasound in Medicine
2.       Abstract 2 of 7Original Research
Classification of Benign and Malignant Thyroid Nodules Using Wavelet Texture Analysis of Sonograms
Objectives—The purpose of this study was to evaluate a computer-aided diagnostic system using texture analysis to improve radiologic accuracy for identification of thyroid nodules as malignant or benign.
Methods—The database comprised 26 benign and 34 malignant thyroid nodules. Wavelet transform was applied to extract texture feature parameters as descriptors for each selected region of interest in 3 normalization schemes (default, μ ± 3σ, and 1%–9%). Linear discriminant analysis and nonlinear discriminant analysis were used for texture analysis of the thyroid nodules. The first–nearest neighbor classifier was applied to features resulting from linear discriminant analysis. Nonlinear discriminant analysis features were classified by using an artificial neural network. Receiver operating characteristic curve analysis was used to examine the performance of the texture analysis methods.
Results—Wavelet features under default normalization schemes from nonlinear discriminant analysis indicated the best performance for classification of benign and malignant thyroid nodules and showed 100% sensitivity, specificity, and accuracy; the area under the receiver operating characteristic curve was 1.
Conclusions—Wavelet features have a high potential for effective differentiation of benign from malignant thyroid nodules on sonography.

o    © 2015 by the American Institute of Ultrasound in Medicine
3.       Abstract 3 of 7Original Research
Acoustic Properties of Breast Fat
Objectives—The American College of Radiology Breast Imaging Reporting and Data System (BI-RADS) atlas for ultrasound (US) qualitatively describes the echogenicity and attenuation of a mass, where fat lobules serve as a standard for comparison. This study aimed to estimate acoustic properties of breast fat under clinical imaging conditions to determine the degree to which properties vary among patients.
Methods—Twenty-four women with solid breast masses scheduled for biopsy were scanned with a Siemens S2000 scanner and 18L6 linear array transducer (Siemens Medical Solutions, Malvern, PA). Offline analysis estimated the attenuation coefficient and backscatter coefficients (BSCs) from breast fat using the reference phantom method. The average BSC was calculated over 6 to 12 MHz to objectively quantify the BI-RADS US echo pattern descriptor, and effective scatterer diameters were also estimated.
Results—A power law fit to the attenuation coefficient versus frequency yielded an attenuation coefficient of 1.28 dB·cm−1 MHz−0.73. The mean attenuation coefficient versus frequency slope ± SD at 7 MHz was 0.73 ± 0.23 dB·cm−1 MHz−1, in agreement with previously reported values. The BSC versus frequency showed close agreement among all patients, both in magnitude and frequency dependence, with a power law fit of (0.6 ± 0.25) ×10−4 sr−1 cm−1 MHz−2.49. The average backscatter in the 6–12-MHz range was 0.004 ± 0.002 sr−1 cm−1. The mean effective scatterer diameter for fat was 60.2 ± 9.5 μm.
Conclusions—The agreement in parameter estimates for breast fat among these patients supports the use of fat as a standard for comparison with tumors. Results also suggest that objective quantification of these BI-RADS US descriptors may reduce subjectivity when interpreting B-mode image data.
o    © 2015 by the American Institute of Ultrasound in Medicine
4.       Abstract 4 of 7Original Research
Central Venous Catheterization
Are We Using Ultrasound Guidance?
Objectives—To assess the self-reported frequency of use of ultrasound guidance for central venous catheterization by emergency medicine (EM) residents, describe residents’ perceptions regarding the use of ultrasound guidance, and identify barriers to the use of ultrasound guidance.
Methods—A longitudinal cross-sectional study was conducted at 5 academic institutions. A questionnaire on the use of ultrasound guidance for central venous catheterization was initially administered to EM residents in 2007. The same questionnaire was distributed again in the 5 EM residency programs in 2013.
Results—In 2007 and 2013, 147 and 131 residents completed questionnaires, respectively. A significant increase in the use of ultrasound guidance for central venous catheterization was reported in 2013 compared to 2007 (P< .001). In 2007, 53% (95% confidence interval, 44%–61%) of residents reported that they were initially trained in central venous catheterization using ultrasound guidance compared to 96% (95% confidence interval, 92%–99%) in 2013 (P < .0001). In 2007, more residents thought that faculty were insufficiently adopting ultrasound (42% versus 9%), and there was a lack of ultrasound teaching during residency training (14% versus 5%) compared to 2013.
Conclusions—The use of self-reported ultrasound guidance for central venous catheterization significantly increased from 2007 to 2013 at academic institutions. Most residents were aware of the benefits of using ultrasound guidance. Although faculty adoption of ultrasound for central venous catheterization remains a barrier, it has decreased.
o    © 2015 by the American Institute of Ultrasound in Medicine
5.       Abstract 5 of 7Original Research
Reliability Assessment of Various Sonographic Techniques for Evaluating Carpal Tunnel Syndrome
Objectives—The aim of this study was to determine the intra- and inter-rater reliability of sonographic measurements of the median nerve cross-sectional area in individuals with carpal tunnel syndrome and healthy control participants.
Methods—The median nerve cross-sectional area was evaluated by sonography in 18 participants with carpal tunnel syndrome (18 upper extremities) and 9 control participants (18 upper extremities) at 2 visits 1 week apart. Two examiners, both blinded to the presence or absence of carpal tunnel syndrome, captured independent sonograms of the median nerve at the levels of the carpal tunnel inlet, pronator quadratus, and mid-forearm. The cross-sectional area was later measured by each examiner independently. Each also traced images that were captured by the other examiner.
Results—Both the intra- and inter-rater reliability rates were highest for images taken at the carpal tunnel inlet (radiologist, r = 0.86; sonographer,r = 0.87; inter-rater, r = 0.95; all P < .0001), whereas they was lowest for the pronator quadratus (r = 0.49, 0.29, and 0.72, respectively; all P < .0001). At the mid-forearm, the intra-rater reliability was lower for both the radiologist and sonographer, whereas the inter-rater reliability was relatively high (r = 0.54, 0.55, and 0.81; all P < .0001). Tracing of captured images by different examiners showed high concordance for the median cross-sectional area at the carpal tunnel inlet (r = 0.96–0.98; P < .0001).
Conclusions—The highest intra- and inter-rater reliability was found at the carpal tunnel inlet. The results also demonstrate that tracing of the median nerve cross-sectional area from captured images by different examiners does not contribute significantly to measurement variability.
o    © 2015 by the American Institute of Ultrasound in Medicine
6.       Abstract 6 of 7Technical Innovation
Can Sonography Distinguish a Supraorbital Notch From a Foramen?
Diagnostic tools for evaluating the supraorbital rim in preparation for nerve decompression surgery in patients with chronic headaches are currently limited. We evaluated the use of sonography to diagnose the presence of a supraorbital notch or foramen in 11 cadaver orbits. Sonographic findings were assessed by dissecting cadaver orbits to determine whether a notch or foramen was present. Sonography correctly diagnosed the presence of a supraorbital notch in 7 of 7 cases and correctly diagnosed a supraorbital foramen in 4 of 4 cases. We found that sonography had 100% sensitivity in diagnosing a supraorbital notch and foramen. This tool may therefore be helpful in characterizing the supraorbital rim preoperatively and may influence the decision to use a transpalpebral or endoscopic approach for supraorbital nerve decompression as well as the decision to use local or general anesthesia.
o    © 2015 by the American Institute of Ultrasound in Medicine
7.       Abstract 7 of 7Technical Innovation
Perisciatic Ultrasound-Guided Infiltration for Treatment of Deep Gluteal Syndrome
Description of Technique and Preliminary Results
The objective of this study was to describe a perisciatic ultrasound-guided infiltration technique for treatment of deep gluteal syndrome and to report its preliminary clinical results. A mixture of saline (20 mL), a local anesthetic (4 mL), and a corticosteroid solution (1 mL) was infiltrated in the perisciatic region between the gluteus maximus and pelvitrochanteric muscles. Relative pain relief was achieved in 73.7% of the patients, with average preprocedural and postprocedural visual analog scale scores of 8.3 and 2.8, respectively. Fifty percent of patients reported recurrence of discomfort, and the average duration of the therapeutic effect in these patients was 5.3 weeks.
o    © 2015 by the American Institute of Ultrasound in Medicine
Copyright © 2015 by the American Institute of Ultrasound in Medicine

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