• The Journal of the Acoustical Society of Korea
• /
• v.27 no.3E
• /
• pp.84-94
• /
• 2008

Displacement estimation is a crucial step in ultrasonic strain imaging. The displacement between a pre- and postcompression signal in the current data window is estimated by first shifting the postcompression signal by the displacement obtained in the previous data window to reduce their decorrelation and then determining the remaining part of the displacement through autocorrelation and conversion of phase difference into time delay. However, since strain image quality tends to vary with the amount of compression applied, we propose two new methods for enhancing strain image quality, i.e., displacement normalization and adaptive persistence. Both in vitro and in vivo experiments are carried out to acquire ultrasound data and produce strain images in real time under the application of quasi static compression. The experimental results demonstrate that the methods are quite effective in improving strain image quality and thus can be applied to implementing an ultrasound elasticity imaging system that operates in real time.

• Journal of Biomedical Engineering Research
• /
• v.24 no.3
• /
• pp.141-149
• /
• 2003

This paper proposes a method of measuring and imaging the stiffness of human soft tissue to diagnose cancers or tumors which have been difficult to detect in ultrasound B-mode imaging systems. To measure the soft tissue stiffness, sinusoidal vibrations are applied to it, and the magnitude of its mechanical vibration is determined by estimating the temporal variation of speckle pattern brightness in ultrasound B-mode images. It is verified by simulation and experiment that the proposed method can estimate the relative tissue stiffness from B-mode images with a relatively small amount of computation.

• Korean Journal of Veterinary Research
• /
• v.62 no.1
• /
• pp.7.1-7.4
• /
• 2022

A 7-year-old Scottish Straight cat presented with hypersalivation and generalized hyperesthesia. The cat was provided tuna-based food for 2 to 3 weeks before clinical symptoms appeared. Abdominal ultrasonography showed a heterogeneous, hyperechoic mesentery with hypoechoic foci. Pansteatitis was tentatively diagnosed and the cat was treated with vitamin E, anti-inflammatory drugs, and dietary changes. The clinical signs and changes in mesenteric fat on serial ultrasonography resolved. After feeding tuna-based food again, the same clinical signs and mesenteric changes on ultrasound recurred, which recovered through the same treatment. This study suggests that ultrasonography can be useful for diagnosis and monitoring of feline pansteatitis.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.1
• /
• pp.468-475
• /
• 2018

In medical ultrasound imaging, frequency-dependent attenuation downshifts and reduces a center frequency and a frequency bandwidth of received echo signals, respectively. This causes considerable errors in quadrature demodulation (QDM), result in lowering signal-to-noise ratio (SNR) and contrast resolution (CR). To address this problem, adaptive dynamic QDM (ADQDM) that estimates center frequencies along depth was introduced. However, the ADQDM often fails when imaging regions contain hypoechoic regions. In this paper, we introduce a valid region-based ADQDM (VR-ADQDM) method to reject the misestimated center frequencies to further improve SNR and CR. The valid regions are regions where the center frequency decreases monotonically along depth. In addition, as a low-pass filter of QDM, Gaussian wavelet based dynamic filtering was adopted. From the phantom experiments, average SNR improvements of the ADQDM and the VR-ADQDM over the traditional QDM were 1.22 and 5.27 dB, respectively, and the corresponding maximum SNR improvements were 2.56 and 10.58 dB. The contrast resolution of the VR-ADQDM was also improved by 0.68 compared to that of the ADQDM. Similar results were obtained from in vivo experiments. These results indicate that the proposed method would offer promises for imaging technically-difficult patients due to its capability in improving SNR and CR.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.32 no.5
• /
• pp.484-493
• /
• 2012

Since the 1980s, there have been many research activities devoted to quantitatively characterizing and imaging human tissues based on sound speed, attenuation coefficient, density, nonlinear B/A parameter, etc., but those efforts have not yet reached the stage of commercialization. However, a new imaging technology termed elastography, which was proposed in the early 1980s, has recently been implemented in commercial clinical ultrasound scanners, and is now being used to diagnose prostates, breasts, thyroids, livers, blood vessels, etc., more quantitatively as a complementary adjunct modality to the conventional B-mode imaging. The purpose of this article is to introduce and review various elastographic algorithms for use in quasistatic or static compression type elasticity imaging modes. Most of the algorithms are based on the crosscorrelation or autocorrelation function methods, and the fundamental difference is that the time shift is estimated by changing the lag variable in the former, while it is directly obtained from the phase shift at a fixed lag in the latter.

• Clinics in Shoulder and Elbow
• /
• v.18 no.3
• /
• pp.172-193
• /
• 2015

Nowadays shoulder ultrasound is commonly used in the assessment of shoulder diseases and is as accurate as magnetic resonance imaging in the detection of several pathologies. Operator dependence is the main disadvantage of shoulder ultrasound. After adhering to a strict examination protocol, good knowledge of normal anatomy and pathologic processes and an awareness of common pitfalls, it can be used as a focused examination providing rapid, real-time diagnosis, and treatment by ultrasound-guided interventions in desired clinical situations. Also shoulder ultrasound can help the surgeon decide whether treatment will be surgical or nonsurgical. If arthroscopy is planned, sonographic findings help to counsel patients regarding surgical and functional outcomes. If a nonsurgical approach is indicated, ultrasound can be used to follow patients. This review article presents the examination techniques, the normal sonographic appearances and the main pathologic conditions found in shoulder ultrasound. And also addresses a simplified approach to scanning and ultrasound-guided intervention. Knowledge of optimal techniques, normal anatomy, dynamic maneuvers, and pathologic conditions is essential for optimal performance and interpretation of images.

• Journal of Korean Neurosurgical Society
• /
• v.66 no.3
• /
• pp.239-246
• /
• 2023

Germinal matrix and intraventricular hemorrhage (GM-IVH) are the major causes of intracranial hemorrhage in premature infants. Cranial ultrasound (cUS) is the imaging modality of choice for diagnosing and classifying GM-IVH. Magnetic resonance imaging (MRI), usually performed at term-equivalent age, is more sensitive than cUS in identifying hemorrhage in the brain. Post-hemorrhagic ventricular dilatation is a significant complication of GM-IVH and correlates with adverse neurodevelopmental outcomes. In this review, we discuss the various imaging findings of GM-IVH in premature infants, focusing on the role of cUS and MRI.

• Asian Pacific Journal of Cancer Prevention
• /
• v.13 no.5
• /
• pp.2081-2085
• /
• 2012

Background: To investigate the value of ultrasound elastography (UE) in the differentiation between benign and malignant enlarged cervical lymph nodes (LNs). Methods: B-mode ultrasound, power Doppler imaging and UE were examined to determine LN characteristics. Two kinds of methods, 4 scores of elastographic classification and a strain ratio (SR) were used to evaluate the ultrasound elastograms. Results: The cutoff point of SR had high utility in differential diagnosis of benign and malignant of cervical lymph nodes, with good sensitivity, specificity and accuracy. Conclusion: UE is an important aid in differential diagnosis of benign and malignant cervical LNs.

• The Korean Journal of Pain
• /
• v.26 no.2
• /
• pp.111-124
• /
• 2013

Ultrasound has emerged to become a commonly used modality in the performance of chronic pain interventions. It allows direct visualization of tissue structure while allowing real time guidance of needle placement and medication administration. Ultrasound is a relatively affordable imaging tool and does not subject the practitioner or patient to radiation exposure. This review focuses on the anatomy and sonoanatomy of peripheral non-axial structures commonly involved in chronic pain conditions including the stellate ganglion, suprascapular, ilioinguinal, iliohypogastric, genitofemoral and lateral femoral cutaneous nerves. Additionally, the review discusses ultrasound guided intervention techniques applicable to these structures.

• Physical Therapy Rehabilitation Science
• /
• v.5 no.1
• /
• pp.47-52
• /
• 2016

Objective: This study surveyed the perceptions of physical therapists on muscle re-education through visual feedback obtained from rehabilitative ultrasound imaging (RUSI). Design: Survey. Methods: For this study, 500 physical therapists who participated in a refresher training held by the Seoul City Association in March 2015 were selected for a questionnaire-based survey. Subjects were randomly selected targets physiotherapists who participated in a refresher training.The questionnaire had 21 items in total. Questions 1 to 15 could be answered by everyone. However, questions 16 to 21 could be answered only by people who used RUSI. Results: The majority of respondents were aged 20 to 30 years. Respondents in their twenties, thirties, forties, and fifties accounted for 32.4%, 40.2%, 21.9%, and 5.6%respectively. Therapists with careers spanning one to 5 years accounted for 27.8%, while those with careers spanning 5 to 10 years and 10 to 15 years accounted for 34.6% and 17.0%, respectively. Those with careers over 20 years accounted for 9.2%. The types of work have not been various including work related to the nervous system (49.0%), the musculoskeletal system (41.5%), sports (0.7%), juvenile physical therapy (4.2%), and others (4.6%). Conclusions: In this study, we examined the perceptions of physical therapists on rehabilitation ultrasound imaging used in muscle re-education. We also examined how to use this technique. Many therapists who participated in the refresher training were found to be unaware of RUSI. In the future, further investigations on RUSI for muscle re-education are required through refresher training or training lectures at the national level.