• Korean Journal of Radiology
• /
• v.23 no.1
• /
• pp.52-59
• /
• 2022

Objective: To investigate whether the diagnostic performance of CT angiography (CTA) could be improved by modifying the conventional criterion (anastomosis site abnormality) to diagnose hepatic artery occlusion (HAO) after liver transplantation (LT) in suspected patients with Doppler ultrasound (US) abnormalities. Materials and Methods: One hundred thirty-four adult LT recipients (88 males and 46 females; mean age, 52.7 years) with suspected HAO on Doppler US (40 HAO and 94 non-HAO according to the reference standards) were included. We evaluated 1) abnormalities in the HA anastomosis, categorized as a cutoff, ≥ 50% stenosis at the anastomotic site, or diffuse stenosis at both graft and recipient sides around the anastomosis, and 2) abnormalities in the distal run-off, including invisibility or irregular, faint, and discontinuous enhancement. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of the conventional (considering anastomosis site abnormalities alone) and modified CTA criteria (abnormalities in both the anastomosis site and distal run-off) for the diagnosis of HAO were calculated and compared using the McNemar test. Results: By using the conventional criterion to diagnose HAO, the sensitivity, specificity, PPV, NPV, and accuracy were 100% (40/40), 74.5% (70/94), 62.5% (40/64), 100% (70/70), and 82.1% (110/134), respectively. The modified criterion for diagnosing HAO showed significantly increased specificity (93.6%, 88/94) and accuracy (93.3%, 125/134) compared to that with the conventional criterion (p = 0.001 and 0.002, respectively), although the sensitivity (92.5%, 37/40) decreased slightly without statistical significance (p = 0.250). Conclusion: The modified criterion considering abnormalities in both the anastomosis site and distal run-off improved the diagnostic performance of CTA for HAO in suspected patients with Doppler US abnormalities, particularly by increasing the specificity.

• The Journal of the Acoustical Society of Korea
• /
• v.27 no.2
• /
• pp.80-86
• /
• 2008

Breast ultrasound has many advantages over mammography but suffers from a shortcoming of being not suitable in detecting microcalcification. We studied on a method based on acoustic resonance and power Doppler to detect calcification of breast tissue using a typical 7.5 MHz linear probe used in breast ultrasound examination. We first constructed a breast tissue phantom made of gelatin and then observed calcified legions as external vibrations varied. Calcification injected to the breast tissue phantom being resonated different from the surrounding medium, and its acoustic resonance driven by external vibrations was visualized by differences for color brightness and area in ROI of power doppler. In low frequency regions, the acoustic resonance almost not appeared and showed a plateau in $300{\sim}600\;Hz$ and the color vanished as the frequency further increased.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.8 no.5
• /
• pp.1047-1056
• /
• 2007

Basically, an ultrasonic imaging system has two fundamental imaging modes available. One is the B-mode imaging modality which provides an image of reflection coefficient, and the other is the Doppler color flow mode that maps blood flow inside the human heart and blood vessels. This paper presents a new method of detecting and compensating for aliasing that occurs when the Doppler frequency exceeds one-half of the pulse-repetition frequency (PRF). Its validity is shown by computer simulation. The new method not only extends the measurable Doppler frequency, but also helps to reduce the effect of noise. The results show that the aliasing can be compensated for correctly fur signal-to-noise ratios down to 20 dB.

• Journal of radiological science and technology
• /
• v.44 no.1
• /
• pp.15-23
• /
• 2021

In this case analysis, a patient was diagnosed with subarachnoid hemorrhage (SAH) in a 49-year-old female and showed persistent vasospasm after coil emboilzation in an aneurysm. The patient suffered from persistent vasospasm and performed angioplasty a total of 6 times. Transcranial color coded doppler (TCCD) was performed 12 times to monitor vasospasm. As a result, repetitive cerebral blood flow tests were low cost and safely performed without exposure to invasive radiation through the TCCD, and the repeatability and reproducibility of the test were confirmed with the capabilities of a trained professional radiological technologist.

• Asian Pacific Journal of Cancer Prevention
• /
• v.15 no.8
• /
• pp.3555-3559
• /
• 2014

Background: The triple-negative breast cancer (TNBC) is an aggressive cancer characterized by the absence of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2). Preoperative mammography and ultrasound features of TNBC may potentially suggest characteristics of the disease and assist in treatment decisions. Materials and Methods: The study covered 153 patients with TNBC from May 2011 to May 2012 who were confirmed by postoperative pathology results in our hospital. We compared the radiological findings among the patients and sought to determine the significant iconographic features. The biomarkers p53 and Ki-67 are regarded as significant factors in TNBC. They were therefore used to divide the TNBC into four groups for assessment of relationships with TNBC imaging features. Results: On mammography, most TNBCs exhibit obscure (44.3%) masses. On ultrasound, the majority of masses (95.4%) were predominantly indistinct (50.7%), irregular (76.0%) or featuring posterior echo enhancement/shadowing. Color Doppler flow imaging (CDFI) emphasized hypervascular (32.9%) masses. Differences in CDFI by ultrasound among the four groups were statistically significant (p=0.009). There were obvious differences in the percentages of spiculated margin (p=0.049) and intensive posterior echo (p=0.006) with spotty flow imaging by ultrasound between the Ki-67 (+) p53 (+) and other groups. Conclusions: A combination of mammography and ultrasound revealed the imaging characteristics of TNBC included an obscure mass with less attenuated posterior echoes and some vascularity. A worse prognosis was associated with spiculated margin and intensive posterior echoes with spotty flow imaging.

• Smart Structures and Systems
• /
• v.22 no.2
• /
• pp.223-230
• /
• 2018

This study examines a non-contact laser scanning-based ultrasound system, called an angular scan pulse-echo ultrasonic propagation imager (A-PE-UPI), that uses coincided laser beams for ultrasonic sensing and generation. A laser Doppler vibrometer is used for sensing, while a diode pumped solid state (DPSS) Q-switched laser is used for generation of thermoelastic waves. A high-speed raster scanning of up to 10-kHz is achieved using a galvano-motorized mirror scanner that allows for coincided sensing and for the generation beam to perform two-dimensional scanning without causing any harm to the surface under inspection. This process allows for the visualization of longitudinal wave propagation through-the-thickness. A pulse-echo ultrasonic wave propagation imaging algorithm (PE-UWPI) is used for on-the-fly damage visualization of the structure. The presented system is very effective for high-speed, localized, non-contact, and non-destructive inspection of aerospace structures. The system is tested on an aluminum honeycomb sandwich with disbonds and a carbon fiber-reinforced plastic (CFRP) honeycomb sandwich with a layer overlap. Inspection is performed at a 10-kHz scanning speed that takes 16 seconds to scan a $100{\times}100mm^2$ area with a scan interval of 0.25 mm. Finally, a comparison is presented between angular-scanning and a linear-scanning-based pulse-echo UPI system. The results show that the proposed system can successfully visualize defects in the inspected specimens.

• Journal of Biomedical Engineering Research
• /
• v.19 no.3
• /
• pp.313-320
• /
• 1998

Tri-phasic pulsatile flow is the general flow pattern of human circulary system. In emulating the various situation of cardiovascular system, it is essential to make tri-phasic source flow. To emulate tri-phasic pulsatile flow, we used electro-hydronic style LVAD(Left Ventricular Assist Device) with glass phantom and rubber tube. We have selected control parameters and examined the changing effect of each parameter by using Doppler ultrasound. In this experiment, it was shown that the distal compliance and the break time were the major factors to form tri-phasic flow. The results make it possible to emulate and explain the various situation of human vascular system. In this point, this results will be an useful method in the clinic application.

• The Journal of the Korean dental association
• /
• v.57 no.11
• /
• pp.690-699
• /
• 2019

Ultrasound sonography(US) is used to evaluate various diseases of maxillofacial region including salivary glands, soft tissue and jaw lesions because of easy accessibility and no hazard of ionizing radiation. Also, US can offer dynamic study showing real-time images during diagnostic or surgical procedure. US images provide accurate information about the internal features of lesions on the jaw prior to surgical treatment. Doppler images are used to visualize the vascular distribution of the lesions and to provide additional information to enhance diagnostic value. Nevertheless, the clinical application of US imaging is limited in the dental field. This is due to the lack of knowledge about the US image and the image characteristics of the anatomical structures. It is necessary to evaluate the diagnostic value of US and evaluate its usefulness by looking at clinical cases using US images. Therefore, US imaging may be recommended as an assistant image in evaluating jaw lesions. US images provided accurate information about the internal structure of lesions on the jaw prior to surgical treatment, and diagnostic value was enhanced by visualizing the vascular distribution of the lesion using doppler imaging.

• Journal of the Korean Society of Radiology
• /
• v.17 no.5
• /
• pp.751-759
• /
• 2023

Breast ultrasonography is difficult to image in fatty breasts and to find micro-calcification, but the discovery of micro-calcification is very important for breast cancer screening. Among the color Doppler artifact of ultrasound, twinkle artifact mainly occur on strong reflectors such as stones or calcification in images, and evaluation methods using them are clinically being used. In this study, we are conducting experiments on the color Doppler settings of ultrasound equipment, such as repetition frequency, ensemble, persist, wall filtering, smoothing, linear density, and dissociation value, by producing a breast simulation phantom using the largest amount of calcium phosphate among breast implants. The purpose of this study was to improve the contrast of twinkle artifact in breast ultrasound examinations and to maximize their use in clinical practice. As a result, the pulse repetition frequency occurred in the range of 3.6 kHz to 7.2 kHz, and did not occur above 10.5 kHz. For ensembles, twinkle artifact occurred in all sizes of calcification under low conditions, and in threshold settings, the twinkle artifact increased slightly only under 80 to 100 conditions, and did not occur in 1 mm size calcification. Persist, wall filter, smoothing, and line density settings did not have much meaning in the setting variable because conditions did not increase by condition, and pulse repetition frequency, ensemble, and thresholds had the greatest impact on the twinkling artifact image. This study is expected to help examiners select optimal conditions to effectively increase twinkle artifact by adjusting color Doppler settings.

• The Journal of Korean Orthopaedic Ultrasound Society
• /
• v.7 no.2
• /
• pp.98-104
• /
• 2014

Purpose: To evaluate the incidence of deep vein thrombosis (DVT) before hip fracture by duplex color Doppler ultrasonography. Materials and Methods: From June 2013 to May 2014, 27 patients who had agreed to perform color Doppler ultrasonography before hip fracture surgery were evaluated for the incidence of DVT. Patients who had history of DVT were excluded. Five patients were men and 19 patients were women. The mean age was 74.3 years old (41-87). There were 15 cases of femoral neck fracture, 11 cases of intertrochanteric fractures and one case of acetabular fracture. Surgical intervention underwent within 48 hours from admission and duplex color Doppler ultrasonography was carried out at the day of admission. Results: DVT occurred in six cases (22.2%). Four cases (14.8%) occurred in proximal deep vein and two cases (7.4%) occurred in distal deep vein. The mean period of immobilization was longer in patients who had DVT. But there was no significant difference. The mean age was 79 years old (75-87) in patients who had DVT and 72 years old (65-86) in patients who had not. There was significant difference (p=0.038). Conclusion: The incidence of DVT which was diagnosed by duplex color Doppler ultrasonography before hip fracture surgery was relatively high (22.2%). So it is necessary to undergo duplex color Doppler ultrasonography more aggressively to rule out DVT before hip fracture surgery.