Background: Safe values for quantitative perfusion parameters of indocyanine green (ICG) angiography have not been fully defined, and interpretation remains at the surgeon’s discretion. This prospective observational study aimed to establish the safe values for the quantitative perfusion parameters by comparing tissue oxygenation levels from HSI images in laparoscopic colorectal surgery. Methods: ICG angiography was performed using a laparoscopic near-infrared (NIR) camera system with ICG diluted in 10 mL of distilled water. For quantitative perfusion parameters, the changes in fluorescence intensity with perfusion times were analyzed to plot a time–fluorescence intensity graph. To assess real-time tissue oxygen saturation (StO₂) in the colon, the TIVITA^® Tissue System was utilized for hyperspectral imaging (HSI) acquisition. The StO₂ levels were compared with the quantitative perfusion parameters derived from ICG angiography at corresponding points to define the safe range of ICG parameters reflecting good tissue oxygenation. Results: In the regression analysis, T_1/2MAX, T_MAX, slope, and NIR perfusion index were correlated with tissue oxygen saturation. Using this regression model, the cutoff values of quantitative perfusion parameters were calculated as T_1/2MAX ≤ 10 s, T_MAX ≤ 30 s, slope ≥ 5, and NIR perfusion index ≥50, which best reflected colon StO₂ higher than 60%. Diagnostic values were analyzed to predict colon StO₂ of 60% or more, and the ICG perfusion parameters T_1/2MAX, T_MAX, and perfusion TR showed high sensitivity values of 97% or more, indicating their ability to correctly identify cases with acceptable StO₂. Conclusion: The safe values for quantitative perfusion parameters derived from ICG angiography were T_1/2MAX ≤ 10 s and T_MAX ≤ 30 s, which were associated with colon tissue oxygenation levels higher than 60% in the laparoscopic colorectal surgery.

Gyung Mo Son, Hong-min Ahn, In Young Lee, Sun Min Lee, Sang-Ho Park, Kwang-Ryul Baek. Journal of Minimally Invasive Surgery 2021;24:113-22. https://doi.org/10.7602/jmis.2021.24.3.113

Various sensors are embedded in automobiles to implement intelligent safety technologies such as autonomous driving and front–rear collision avoidance technology. In particular, ultrasonic sensors have been used in the past because they have an accuracy of centimeters to sub-centimeters in air despite their low cost and low hardware complexity. Recently, the crosstalk problem between ultrasonic sensors has been raised because the number of ultrasonic sensors in the unit space has increased as the number of vehicles increases. Various studies have been conducted to solve the crosstalk, but a demodulation error occurs when signals overlap. Therefore, in this paper, we propose a method that is robust to ultrasonic signal overlap, is robust even at shorter code length, and has reduced time of flight (TOF) error compared to the existing method by applying frequency sweep keying modulation based on code division multiple access (CDMA). As a result of the experiment, the code was detected accurately regardless of the overlap ratio of the two signals, and it was robust even in situations where the power of the two signals was different. In addition, it shows an accurate TOF estimation even if the ID code length is shorter than the existing on–off-keying, frequency shift keying, and phase shift keying methods.

Background and Objectives: This study aimed to determine the minimal effective dose of indocyanine green (ICG) required for accurately assessing colonic perfusion during laparoscopic colorectal surgery using a laser-assisted laparoscopic near-infrared (NIR) camera system. Materials and Methods: In 15 patients with colorectal cancer undergoing right hemicolectomy, the left branch of the middle colic artery was preserved, and ICG angiography was performed in the transverse colon. To determine the optimal ICG dose, experimental doses of 0.01, 0.02, 0.03, 0.04, and 0.05 mg of ICG per patient’s body weight (kg) were administered intravenously in each group. Additionally, a conventional dose of 0.2 mg/kg was administered in the same patients more than 30 min after the initial dose. For quantitative analysis, the fluorescent expression region was extracted, and fluorescence intensity was analyzed using automatic image processing. Analysis accessibility, T_1/2MAX, perfusion time ratio, slope, artificial intelligence (AI)-based perfusion pattern analysis, and washout time were measured in 150 detailed regions of interest in each image. Results: Group 1 (0.01 mg/kg) showed significantly lower accessibility rates for quantitative analysis (48.0%) compared with Groups 2–5 (84.7–100%). The mean slope value in Group 1 was 3.7, which fell below the acceptable threshold (>4) and was significantly lower than that of the other groups (p < 0.001). An acceptable AI-based perfusion pattern was 14.2% in Group 1, significantly lower than in Groups 2–5 (66.4–100%). Washout time was significantly faster with minimal doses compared with conventional doses (39.0 ± 15.8 s vs. 117.5 ± 4.9 s, respectively, p < 0.001). Conclusions: This study supports the use of minimal ICG doses, ranging from 0.02 to 0.05 mg/kg, to optimize repetitive ICG angiography using a laser-assisted laparoscopic NIR camera.

초음파 비파괴 검사는 검사 대상물의 훼손 없이 초음파를 이용하여 검사 대상의 결함, 구조 등을 측정하는 검사 방법이다. 고주파 초음파 시스템에서는 송신파와 수신파의 간섭 및 경로에 의해 SNR이 나빠지는데 이중 프로브를 사용하는 초음파 비파괴 검사 시스템은 초음파 송신파와 수신파의 경로를 분리함으로써 간섭을 줄일 수 있는 장점이 있으나 공간 분해능이 나빠지는 단점이 있다. 본 논문에서는 이중 프로브 초음파 비파괴 검사시스템에서 공간 분해능이 나빠지는 원인을 설명하고 그로인한 단점을 해결하기 위해 검사 대상을 90도 회전하여 한 번 더 측정하고 2D-DWT를 이용해 두 검사 결과를 결합하여 공간 분해능이 개선된 결과를 얻는 방법을 제안한다. 이중 프로브 초음파 검사 시스템을 구현하여 단일 검사 결과와 제안 방법의 결과를 비교하여 공간 분해능이 향상된 것을 보인다.

Shape from focus enables microscopic 3D sensing by combining it with a microscope system. However, edge bleeding artifacts of estimated depth easily occur in this environment. Therefore, this study analyzed artifacts and proposed a method to reduce edge bleeding artifacts. As a result of the analysis, the artifact factors are the depth of field of the lens, object texture, brightness difference between layers, and the slope of the object. Additionally, to reduce artifacts, a weighted focus measure value method was proposed based on the asymmetry of local brightness in artifacts. The proposed reduction method was evaluated through simulation and implementation. Edge bleeding artifact reduction rates of up to 60% were shown in various focus measure operators. The proposed method can be used with postprocessing algorithms and reduces edge bleeding artifacts.