Official Proceedings - AIUM

American Institute of Ultrasound in Medicine Proceedings J Ultrasound Med 32(suppl):S1–S134, 2013Conclusions—Our proposed automated system uses a novelcombination of DWT and HOS features to adequately characterizeprostate TRUS images. On evaluation, the system presented high accuracyof 97.95% in detecting CaP. Thus, the preliminary results indicate that theUroImage system can be an adjunct tool to provide an initial diagnosis forthe identification of patients with prostate cancer.1540270 Quantitative Ultrasound as an Aid to Differentiate BenignFrom Malignant Breast MassesHaidy Nasief, Ivan Rosado-Mendez, James Zagzebski,Timothy Hall* Medical Physics, University of Wisconsin,Madison, Wisconsin USAObjectives—Ultrasound attenuation (Att), backscatter coefficients(BSC), effective scatterer diameter (ESD), and a scatterer size “heterogeneityindex”(HI) give useful insight into the nature of a breast mass.The purpose of this study was to evaluate the potential of these quantitativefeatures, both individually and in combination, to differentiate benignfrom malignant breast masses.Methods—Radiofrequency echo data from 26 patients scheduledfor ultrasound-guided biopsy of suspicious breast masses were obtained,along with conventional grayscale and color flow images. Scanswere done using a Siemens Acuson S2000 equipped with an 18L6 lineararray transducer. Beam-steered acquisitions ranging between –20° to 20°were obtained in both radial and antiradial planes projecting through themass. Att and BSC within masses were measured using the referencephantom method. ESDs were estimated using the BSC vs frequency dataand a Gaussian form factor. HI was characterized using the SD among theESD estimates (ignoring correlations among them). Isotropic features ofthe masses were studied by computing power law fits of Att vs frequencyat each beam-steering angle. Combinations of quantitative ultrasound parameterswere examined with a Bayesian classifier to estimate those withthe strongest influence on characterization.Results—The mean Att in dB/cm-MHz was slightly higher forcarcinomas (1.3 ± 0.7) than fibroadenomas (1.1 ± 0.5), the average valueof the ESD was smaller for carcinomas (83.1 ± 9.8 µm) than for fibroadenomas(97.8 ± 13.1 µm), and carcinomas exhibited lower HI thanfibroadenomas. Surprisingly, both tumor types exhibited a certain degreeof anisotropic behavior. However, considerable overlap exists in backscatterand attenuation properties of benign and malignant masses. Using onlypairs of parameters to classify the disease type performed relatively poorly,but the performance of a Bayesian classifier combining 3 parameters (Att,ESD, and HI) was cautiously encouraging (all classified correctly but ona very limited data set).Conclusions—Att, ESD, and HI show promise for characterizingbreast masses. Very promising results are possible using combinationsof these 3 parameters.1536102 Stochastic Hidden Markov Model–Based FilteringAlgorithm for Tracking Shear Waves Through DisparateMedia in Electrode Vibration ElastographyAtul Ingle, 1 * Tomy Varghese 1,2 1 Electrical and ComputerEngineering, 2 Medical Physics, University of Wisconsin, Madison,Wisconsin USAObjectives—Much research effort in quantitative ultrasoundelastography has been directed toward methods for setting up shear wavesin tissue and modeling wave propagation characteristics. However, dataprocessing has been mostly limited to using off-the-shelf function-fittingalgorithms. The present work proposes a specialized noise-filtering algorithmto improve boundary delineation while reducing the risk of excessivesmoothing.Methods—A shear wave pulse traveling through dissimilarmedia is assumed to have constant velocity while in the same medium,whereas its velocity changes abruptly when it crosses an interface. Ultrasounddisplacement estimates are used to get the time of arrival (TOA) ofthe wave pulse at different locations. The noiseless TOA plot is assumedto be piece-wise linear with unknown transition points. The noisy data aredescribed using a hidden Markov model whose hidden states are the noiselessTOA values and observed states corrupted by Gaussian noise. A particlefilter is then used to unravel the hidden states. An electrode vibrationelastography phantom is used, which consists of 3 different media. A needlebound to an inclusion in the phantom and attached to an actuator isused to set up shear waves.Results—Visual boundary delineation is improved because thisalgorithm uses probabilistic prior information of wave pulse propagation.Mean shear wave velocity estimates are within 1 m/s of those obtainedusing a commercial shear wave imaging system.Conclusions—Model-based algorithms have a potential to significantlyimprove results in shear wave elastography quantitatively interms of estimates of mechanical properties and qualitatively in terms ofthe visualization of stiffness images. (Supported by National Institutes ofHealth grants R01CA112192-05 and R01CA112192-S103.)Table 1Shear Wave Velocity, m/s Young’s Modulus, kPaMechanicalROI EVE SSI EVE SSI TestingInclusion 3.8 ± 2.2 2.8 ± 1.1 57.2 ± 70 24.2 ± 5.8 54.4 ± 0.1Partially ablated 2.0 ± 0.2 2.3 ± 0.8 11.9 ± 2.6 13.3 ± 3.5 21.5 ± 0.3Background 1.3 ± 0.2 1.3 ± 0.4 5.0 ± 1.9 4.8 ± 0.5 3.7 ± 0.1EVE indicates electrode vibration elastography; ROI, region of interest; and SSI,supersonic shear imaging.1540426 Viscoelastic Strain Response Ultrasound Assessment of SerialChanges in the Viscoelastic Property and Compositionof Human Dystrophic Muscle In VivoMallory Scola, 1 Melissa Caughey, 2 Diane Meyer, 3 ReginaEmmitt, 3 James Howard, 2,4 Manisha Chopra, 4 CaterinaGallippi 1 *1 Joint Department of Biomedical Engineering,2Medicine, 3 Physical and Occupational Therapy, 4 Neurology,University of North Carolina, Chapel Hill, North Carolina USAObjectives—In Duchenne muscular dystrophy (DMD), wheremuscle tissue undergoes necrosis and is replaced by fat and collagen, delineatingthe complex and poorly understood disease process and monitoringresponses to novel therapies may be facilitated by imaging muscleviscoelasticity. Viscoelastic strain response (ViSR) ultrasound is a methodfor quantitatively evaluating the relaxation time constant, τ, in the Voigtmodel. The objective of this work is to demonstrate ViSR’s clinical relevanceto monitoring dystrophic muscle degeneration over time. We hypothesizethat ViSR ultrasound detects changes in percent fat/necrosiscomposition in DMD muscles that correspond to altered physical performance.Methods—ViSR ultrasound was performed on a 5-year-old boywith DMD at baseline and at 4-month follow-up using a Siemens AcusonAntares imaging system equipped for modifiable beam sequencing and aVF7-3 transducer. The acquired ViSR data were processed to calculate τ,and parametric 2D ViSR τ images were rendered. Fat/necrosis compositionwas calculated as the percent muscle area with ViSR τ values abovean empirically determined threshold. Within 1 hour following each imagingepisode, the boy underwent standardized timed function tests. ViSRoutcome was compared to physical performance.Results—See Table 1.Conclusions—ViSR ultrasound detected a 39% increase frombaseline to 4-month follow-up in fat/necrosis composition in the rectusfemoris (RF), a 5% decrease in the sartorius (SART), and a 7% increasein the gastrocnemius (GAST), which is consistent with expected phenotypicvariation in these muscles for a 5-year-old boy. The ViSR changeS62