Selected
Abstracts
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.
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© 2015 by the American Institute of Ultrasound in Medicine
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.
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© 2015 by the American Institute of Ultrasound in Medicine
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.
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© 2015 by the American Institute of Ultrasound in Medicine
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.
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© 2015 by the American Institute of Ultrasound in Medicine
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.
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© 2015 by the American Institute of Ultrasound in Medicine
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.
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© 2015 by the American Institute of Ultrasound in Medicine
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.
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© 2015 by the American Institute of Ultrasound in Medicine
Copyright © 2015 by the American Institute of Ultrasound in
Medicine
