• Journal of Biomedical Engineering Research
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• v.45 no.3
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• pp.118-127
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• 2024

Commonly deep learning methods for enhancing the quality of medical images use unpaired dataset due to the impracticality of acquiring paired dataset through commercial imaging system. In this paper, we propose a supervised learning method to enhance the quality of ultrasound images. The U-net model is designed by incorporating a divide-and-conquer approach that divides and processes an image into four parts to overcome data shortage and shorten the learning time. The proposed model is trained using paired dataset consisting of 828 pairs of low-quality and high-quality images with a resolution of 512x512 pixels obtained by varying the number of channels for the same subject. Out of a total of 828 pairs of images, 684 pairs are used as the training dataset, while the remaining 144 pairs served as the test dataset. In the test results, the average Mean Squared Error (MSE) was reduced from 87.6884 in the low-quality images to 45.5108 in the restored images. Additionally, the average Peak Signal-to-Noise Ratio (PSNR) was improved from 28.7550 to 31.8063, and the average Structural Similarity Index (SSIM) was increased from 0.4755 to 0.8511, demonstrating significant enhancements in image quality.

• Korean Journal of Radiology
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• v.25 no.8
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• pp.749-755
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• 2024

The recent surge in the incidence of small papillary thyroid cancers (PTCs) has been linked to the widespread use of ultrasonography, thereby prompting concerns regarding overdiagnosis. Active surveillance (AS) has emerged as a less invasive alternative management strategy for low-risk PTCs, especially for PTCs measuring ≤1 cm in maximal diameter. Recent studies report low disease progression rates of low-risk PTCs ≤1 cm under AS. Ongoing research is currently exploring the feasibility of AS for larger PTCs (<20 mm). AS protocols include meticulous ultrasound assessment, emphasis on standardized techniques, and a multidisciplinary approach; they involve monitoring the nodules for size, growth, potential extrathyroidal extension, proximity to the trachea and recurrent laryngeal nerve, and potential cervical nodal metastases. The criteria for progression, often defined as an increase in the maximum diameter of the PTC, warrant a review of precision and ongoing examinations. Challenges exist regarding the reliability of volume measurements for defining PTC disease progression. Although ultrasonography plays a pivotal role, challenges in assessing progression and minor extrathyroidal extension underscore the importance of a multidisciplinary approach in disease management. This comprehensive overview highlights the evolving landscape of AS for PTCs, emphasizing the need for standardized protocols, meticulous assessments, and ongoing research to inform decision-making.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.13
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• pp.5487-5492
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• 2014

Ultrasonography is non-invasive and can give useful clues in the diagnosis of cervical lymphadenopathy, However, differential diagnosis is difficult in some situations even combined with color Doppler imaging. The present study was conducted to evaluate the clinical value of real time elastography in patients with unexplained cervical lymphadenopathy using a quantitative method. From May 2011 to February 2012, 39 enlarged lymph nodes from 39 patients with unexplained cervical lymphadenopathy were assessed. All the patients were examined by both B-mode ultrasound, color Doppler flow imaging and elastography. The method of analyzing elasto-graphic data was the calculation of the 10 parametres ("mean", "sd", "area%", "com", "kur", "ske", "con", "ent", "idm", "asm") offered by the software integrated into the Hitachi system. The findings were then correlated with the definitive tissue diagnosis obtained by lymph node dissection or biopsy. Final histology revealed 10 cases of metastatic lymph nodes, 11 cases of lymphoma, 12 cases of tuberculosis and 6 cases of nonspecific lymphadenitis. The significant distinguishing features for conventional ultrasound were the maximum short diameter (p=0.007) and absent of echogenic hilum (p=0.0293). The diagnostic accuracy was 43.6% (17/39 cases) and there were 17 patients with equivocal diagnosis. For elastography, "mean" (p=0.003), "area%" (p=0.009), "kurt" (p=0.0291), "skew" (p=0.014) and "cont" (p=0.012) demonstrated significant differences between groups. With 9 of the 17 patients with previous equivocal diagnoses (52.9%) definite and correct diagnoses could be obtained. The diagnostic accuracy for conventional ultrasound combined elastography was 69.2% (27/39 cases). There were differences in the diagnostic sensitivity of the two methods (p=0.0224). Ultrasound combined with elastography demonstrated higher rates of conclusive and accurate diagnoses in patients with unexplained cervical lymphadenopathy than conventional ultrasound. The quantitative program showed good correlation with the pathology of different lymph node diseases.

• Korean Journal of Radiology
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• v.22 no.7
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• pp.1163-1171
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• 2021

Objective: To analyze the correlations between intraoperative ultrasound and MRI metrics of the spinal cord in degenerative cervical myelopathy and identify novel potential predictive ultrasonic indicators of neurological recovery for degenerative cervical myelopathy. Materials and Methods: Twenty-two patients who underwent French-door laminoplasty for multilevel degenerative cervical myelopathy were followed up for 12 months. The Japanese Orthopedic Association (JOA) scores were assessed preoperatively and 12 months postoperatively. Maximum spinal cord compression and compression rates were measured and calculated using both intraoperative ultrasound imaging and preoperative T2-weight (T2W) MRI. Signal change rates of the spinal cord on preoperative T2W MRI and gray value ratios of dorsal and ventral spinal cord hyperechogenicity on intraoperative ultrasound imaging were measured and calculated. Correlations between intraoperative ultrasound metrics, MRI metrics, and the recovery rate JOA scores were analyzed using Spearman correlation analysis. Results: The postoperative JOA scores improved significantly, with a mean recovery rate of 65.0 ± 20.3% (p < 0.001). No significant correlations were found between the operative ultrasound metrics and MRI metrics. The gray value ratios of the spinal cord hyperechogenicity was negatively correlated with the recovery rate of JOA scores (ρ = -0.638, p = 0.001), while the ventral and dorsal gray value ratios of spinal cord hyperechogenicity were negatively correlated with the recovery rate of JOA-motor scores (ρ = -0.582, p = 0.004) and JOA-sensory scores (ρ = -0.452, p = 0.035), respectively. The dorsal gray value ratio was significantly higher than the ventral gray value ratio (p < 0.001), while the recovery rate of JOA-motor scores was better than that of JOA-sensory scores at 12 months post-surgery (p = 0.028). Conclusion: For degenerative cervical myelopathy, the correlations between intraoperative ultrasound and preoperative T2W MRI metrics were not significant. Gray value ratios of the spinal cord hyperechogenicity and dorsal and ventral spinal cord hyperechogenicity were significantly correlated with neurological recovery at 12 months postoperatively.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.399-402
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• 2005

For efficient and accurate diagnosis of ultrasound images, the time gain compensation (TGC) and dynamic range (DR) control of the ultrasound echo signal are important. TGC is for compensating the attenuation of the ultrasound echo signal along the depth, and DR is used to control the image contrast. In this paper, we propose an algorithm for finding the optimized values of TGC and DR automatically. For TGC, the degree of compensation is determined along the depth based on the effective attenuation estimation of ultrasound signal. For DR optimization, we introduce a novel cost function on the basis of the characteristics of ultrasound image, which provides the minimum value at the optimal DR. Experiments have been performed by applying the proposed algorithm to a real US imaging system. The results show that the algorithm automatically can determine the values of TGC and DR in realtime so that the subjective quality of the corresponding US image may be good enough for diagnosis.

• The Journal of Korean Physical Therapy
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• v.23 no.4
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• pp.53-58
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• 2011

Purpose: This study aims to examine the effects of pulsed ultrasound on skin inflammatory reaction induced by ultraviolet irradiation. Methods: Twenty subjects were selected for this study. Inflammatory reaction was induced by ultraviolet irradiation in two areas of the lumbar region of the subjects. Pulsed ultrasound (3 MHz) was applied to one of the two areas of inflammatory reaction at a pulse ratio of 1:4, intensity of $0.5W/cm^2$, once a day for 5 min, and pulsed ultrasound was not applied to the other area. Wound color (chromatic red), luminance (gray) and wound contraction (area) were measured using digital imaging processing method. Results: There was a significant difference in wound color (chromatic red) in the interaction between time and area. There was a significant difference in luminance in the interaction between time and area. There was a significant difference in wound contraction between the two areas. Conclusion: These results indicate that pulsed ultrasound increased the wound contraction rate and reduced the inflammatory reaction activity such as erythema induced by ultraviolet irradiation.

• Journal of the Korean Society of Visualization
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• v.16 no.1
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• pp.15-20
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• 2018

For the measurement of biophysical properties related with cardiovascular diseases (CVD), various microfluidic devices were proposed. However, many devices were monitored by optical equipment. Ultrasound measurement to quantify the biophysical properties can provide new insights to understand the cardiovascular diseases. This study aims to check feasibility of microfluidic device for ultrasound image analysis based on 3D printer. To facilitate acoustic transmission, agarose solution is poured around 3D mold connected with holes of the acrylic box. By applying speckle image velocimetry(SIV) technique, flow information in the bifurcated channel was estimated. Considering that ultrasound signal amplitude is determined by red blood cell (RBC) aggregation, RBC aggregation in the bifurcated channel can be estimated through the analysis of ultrasound signal. As examples of microfluidic device which mimic the CVD model, velocity fields in microfluidic devices with stenosis and aneurysm were introduced.

• The Journal of the Acoustical Society of Korea
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• v.29 no.2E
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• pp.55-63
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• 2010

High Intensity Focused Ultrasound (HIFU) is a noninvasive surgical method mainly targeting deeply located cancer tissue. Ultrasound is generated from an extemally located transducer and the beam is focused at the target volume, so that selective damage can be achieved without harm to overlying or surrounding tissues. The mechanism for cell killing can be combination of thermal and cavitational damage. Although cavitation can be an effective means of tissue destruction, the possibility of massive hemorrhage and the unpredictable nature of cavitational events prevent clinical application of cavitation. Hence, thermal damage has been a main focus related to HIFU research. 2D phased array transducer systems allow electronic scanning of focus, multi-foci, and anti-focus with multi-foci, so that HIFU becomes more applicable in clinical use. Currently, lack of noninvasive monitoring means of HIFU is the main factor to limit clinical applications, but development in MRI and Ultrasound Imaging techniques may be able to provide solutions to overcome this problem. With the development of advanced focusing algorithm and monitoring means, complete noninvasive surgery is expected to be implemented in the near future.

• Journal of Korean Neurosurgical Society
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• v.62 no.1
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• pp.10-26
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• 2019

Magnetic resonance-guided focused ultrasound (MRgFUS) is an emerging new technology with considerable potential to treat various neurological diseases. With refinement of ultrasound transducer technology and integration with magnetic resonance imaging guidance, transcranial sonication of precise cerebral targets has become a therapeutic option. Intensity is a key determinant of ultrasound effects. High-intensity focused ultrasound can produce targeted lesions via thermal ablation of tissue. MRgFUS-mediated stereotactic ablation is non-invasive, incision-free, and confers immediate therapeutic effects. Since the US Food and Drug Administration approval of MRgFUS in 2016 for unilateral thalamotomy in medication-refractory essential tremor, studies on novel indications such as Parkinson's disease, psychiatric disease, and brain tumors are underway. MRgFUS is also used in the context of blood-brain barrier (BBB) opening at low intensities, in combination with intravenously-administered microbubbles. Preclinical studies show that MRgFUS-mediated BBB opening safely enhances the delivery of targeted chemotherapeutic agents to the brain and improves tumor control as well as survival. In addition, BBB opening has been shown to activate the innate immune system in animal models of Alzheimer's disease. Amyloid plaque clearance and promotion of neurogenesis in these studies suggest that MRgFUS-mediated BBB opening may be a new paradigm for neurodegenerative disease treatment in the future. Here, we review the current status of preclinical and clinical trials of MRgFUS-mediated thermal ablation and BBB opening, described their mechanisms of action, and discuss future prospects.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1235-1238
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• 1987

In this paper, a new focusing method, to be called the sampled delay focusing (SDF), is proposed. This method improves the lateral resolution in ultrasound imaging system. In SDF, the analog delay lines are no longer necessary because sampling sum process can replace the conventional delay sum process. Also, this method offers continuous dynamic focusing on the resolution pixel basis if the maximum delay time is less than the sampling interval. Second order sampling is adopted in order to extend the sampling interval.