JUM 01-2013

1/ Fetal Sex and Intrauterine Growth Patterns

Objectives—To analyze the effect of fetal sex on intrauterine growth patterns during the second and third trimesters.

Methods—We conducted a cross-sectional study of women with uncomplicated singleton pregnancies who underwent sonographic fetal weight estimation during the second and third trimesters in a single tertiary center. The effect of fetal sex on intrauterine growth patterns was analyzed for each of the routine fetal biometric indices (biparietal diameter, head circumference, occipitofrontal diameter, abdominal circumference, and femur length) and their ratios. Sex-specific regression models were generated for these indices and their ratios as a function of gestational age. Sex-specific growth curves were generated from these models for each of the biometric indices and their ratios for gestational weeks 15 to 42.

Results—Overall, 12,132 sonographic fetal weight estimations were included in the study. Fetal sex had an independent effect on the relationship between each of the biometric indices and their ratios and gestational age. These effects were most pronounced for biparietal diameter (male/female ratio, 1.021) and the head circumference/femur length and biparietal diameter/femur length ratios (male/female ratios, 1.014 and 1.016, respectively). For the head measurements, these sex-related differences were observed as soon as the early second trimester, whereas for abdominal circumference, the differences were most notable during the late second and late third trimesters.

Conclusions—Female fetuses grow considerably slower than male fetuses, and these differences are observed from early gestation. However, the female fetus is not merely a smaller version of the male fetus, but, rather, there is a sex-specific growth pattern for each of the individual fetal biometric indices. These findings provide support for the use of sex-specific sonographic models for fetal weight estimation as well as the use of sex-specific reference growth charts.

o    © 2013 by the American Institute of Ultrasound in Medicine

2/ Clinical Value of Radiofrequency Ultrasonic Local Estimators in Classifying Breast Lesions

Objectives—We sought to summarize the features of radiofrequency ultrasonic local estimator (RULES) images of benign and malignant masses and to explore the diagnostic value of RULES scores to identify breast lumps.

Methods—A total of 81 women with a mean age ± SD of 41.33 ± 12.03 years (range, 19–68 years) with 82 lesions seen at our hospital were included in this study. Inclusion criteria were Breast Imaging Reporting and Data System grade 2 to 5 breast lesions, preoperative 2-dimensional (2D) ultrasound (US) examinations and RULES image acquisition, no treatment before the US examinations, surgical resection in our hospital, and histopathologic results. Each RULES characteristic was scored on the basis of expected values for malignant characteristics, and this RULES scoring system was assessed by a receiver operating characteristic curve.

Results—Of the 82 lesions, 45 were benign, and 37 were malignant. Malignancy was associated with multiple colors, red as the main color, colors distributed in 3 or more locations, aggregated colors, and more than half of the area filled with colors. A RULES score of 7 had the highest sum of sensitivity (67.6%) and specificity (95.6%) and the highest accuracy (82.9%) for diagnosis of malignancy. When 2D US imaging a Breast Imaging Reporting and Data System category of 4 was combined with a RULES score of 4 to detect breast cancer, the sensitivity was 83.8%; the specificity was 93.3%; and the accuracy increased to 89.0%.

Conclusions—The use of RULES images and characteristics is helpful in differentiating benign and malignant breast lesions. Diagnostic accuracy can be improved by combining 2D US imaging and RULES.

o    © 2013 by the American Institute of Ultrasound in Medicine

3/ Breast Mass Characterization Using 3-Dimensional Automated Ultrasound as an Adjunct to Digital Breast Tomosynthesis

A Pilot Study

Objectives—The purpose of this study was to retrospectively evaluate the effect of 3-dimensional automated ultrasound (3D-AUS) as an adjunct to digital breast tomosynthesis (DBT) on radiologists’ performance and confidence in discriminating malignant and benign breast masses.

Methods—Two-view DBT (craniocaudal and mediolateral oblique or lateral) and single-view 3D-AUS images were acquired from 51 patients with subsequently biopsy-proven masses (13 malignant and 38 benign). Six experienced radiologists rated, on a 13-point scale, the likelihood of malignancy of an identified mass, first by reading the DBT images alone, followed immediately by reading the DBT images with automatically coregistered 3D-AUS images. The diagnostic performance of each method was measured using receiver operating characteristic (ROC) curve analysis and changes in sensitivity and specificity with the McNemar test. After each reading, radiologists took a survey to rate their confidence level in using DBT alone versus combined DBT/3D-AUS as potential screening modalities.

Results—The 6 radiologists had an average area under the ROC curve of 0.92 for both modalities (range, 0.89–0.97 for DBT and 0.90–0.94 for DBT/3D-AUS). With a Breast Imaging Reporting and Data System rating of 4 as the threshold for biopsy recommendation, the average sensitivity of the radiologists increased from 96% to 100% (P > .08) with 3D-AUS, whereas the specificity decreased from 33% to 25% (P > .28). Survey responses indicated increased confidence in potentially using DBT for screening when 3D-AUS was added (P < .05 for each reader).

Conclusions—In this initial reader study, no significant difference in ROC performance was found with the addition of 3D-AUS to DBT. However, a trend to improved discrimination of malignancy was observed when adding 3D-AUS. Radiologists’ confidence also improved with DBT/3DAUS compared to DBT alone.

o    © 2013 by the American Institute of Ultrasound in Medicine

4/ Evaluation of Carotid Artery Stiffness in Obese Children Using Ultrasound Radiofrequency Data Technology

Objectives—The goals of this study were to investigate the difference in carotid arterial stiffness in obese children compared to healthy children and to study the correlation between carotid arterial stiffness parameters and obesity using ultrasound (US) radiofrequency (RF) data technology.

Methods—Carotid artery stiffness parameters, including the compliance coefficient, stiffness index, and pulse wave velocity, were evaluated in 71 obese patients and 47 healthy controls with US RF data technology. In addition, all participants were evaluated for fat thickness in the paraumbilical abdominal wall and fatty liver using abdominal US.

Results—Compared to the control group, the blood pressure (BP), body mass index (BMI), fat thickness in the paraumbilical abdominal wall, presence of fatty liver, and carotid stiffness parameters (stiffness index and pulse wave velocity) were significantly higher in the obese group, whereas the compliance coefficient was significantly lower in the obese group. Furthermore, the pulse wave velocity was weakly positively correlated with the BMI, systolic BP, diastolic BP, and paraumbilical abdominal wall fat thickness, whereas the compliance coefficient was weakly negatively correlated with the systolic BP, BMI, and paraumbilical abdominal wall fat thickness. The presence of a fatty liver was moderately positively correlated with the BMI and weakly positively correlated with the pulse wave velocity.

Conclusions—Ultrasound RF data technology may be a sensitive noninvasive method that can be used to accurately and quantitatively detect the difference in carotid artery stiffness in obese children compared to healthy children. The detection of carotid functional abnormalities and nonalcoholic fatty liver disease in obese children should allow early therapeutic intervention, which may prevent or delay the development of atherosclerosis in adulthood.

o    © 2013 by the American Institute of Ultrasound in Medicine

5/ Evaluation of Liver Tumors Using Acoustic Radiation Force Impulse Elastography and Correlation With Histologic Data

Objectives—Acoustic radiation force impulse (ARFI) technology represents an innovative method for the quantification of tissue elasticity. The aims of this study were to evaluate elasticity by ARFI in both liver tumors and background liver tissue and to compare ARFI measurements with histologic data in liver tumors and background liver.

Methods—Seventy-nine tumors were prospectively studied: 43 benign and 36 malignant. Acoustic radiation force impulse measurements for each tumor type were expressed as mean ± standard deviation for both liver tumors and background liver; ARFI data were also correlated with histologic data.

Results—For liver tumors, the mean stiffness values were 1.90 ± 0.86 m/s for hepatocellular adenoma (n = 9), 2.14 ± 0.49 m/s for hemangioma (n = 15), 3.14 ± 0.63 m/s for focal nodular hyperplasia (n = 19), 2.4 ± 1.01 m/s for hepatocellular carcinoma (n = 24), and 3.0 ± 1.36 m/s for metastasis (n = 12). Important variations were observed within each tumor type or within a single tumor. These variations could have been due to necrosis, hemorrhage, or colloid. There was no statistically significant difference between the benign and malignant groups. Regarding background liver, it was possible to observe pathologic abnormalities in histologic analyses or liver function tests to explain the ARFI data. The degree of fibrosis was not the only determinant of liver stiffness in background liver; other factors such as portal embolization, sinusoidal obstruction syndrome caused by chemotherapy, and cholestasis, also could have interfered.

Conclusions—Acoustic radiation force impulse elastography could not allow differentiation between benign and malignant tumors. This study provides a better understanding of the correlation between ARFI and histologic data for both tumors and background liver.

o    © 2013 by the American Institute of Ultrasound in Medicine

6/ Ultra–Minimally Invasive Sonographically Guided Carpal Tunnel Release

Anatomic Study of a New Technique

Objectives—The purposes of this study were to measure a safe zone and a path for ultra–minimally invasive sonographically guided carpal tunnel release with a 1-mm incision in healthy volunteers and then test the procedure in cadavers.

Methods—First, a previously reported sonographic zone was defined as the space between the median nerve and the closest ulnar vascular structure. Axially, the safest theoretical cutting point for carpal tunnel release was set by bisecting this zone. Magnetic resonance imaging was used for axially determining the limits of the sectors (origin at the cutting point) that did not enclose structures at risk (arteries and nerves) and coronally for determining whether our release path could require directions that could potentially compromise safety (origin at the pisiform’s proximal pole). Second, in cadavers, we performed ultra–minimally invasive sonographically guided carpal tunnel release from an intracarpal position through a 1-mm antebrachial approach. Efficacy (deepest fibrous layer release rate), safety (absence of neurovascular or tendon injury), and damage to any anatomy superficial to transverse carpal ligament were assessed by dissection.

Results—All 11 of our volunteers (22 wrists) had safe axial sectors located volar and radially of at least 80.4º (considered safe). Release path directions were theoretically safe (almost parallel to the longitudinal axis of the forearm). In 10 cadaver wrists, ultra–minimally invasive sonographically guided carpal tunnel release was effective (100% release rate) and safe without signs of intrusion into the superficial anatomy.

Conclusions—Ultra–minimally invasive sonographically guided carpal tunnel release in a safe sonographic zone may be feasible The technique preserves the superficial anatomy and diminishes the damage of a surgical approach.

o    © 2013 by the American Institute of Ultrasound in Medicine