1.Coronary CT Angiography-Derived Fractional Flow Reserve in Asia and the United States: 2025 Status Update
Woo Jin AHN ; Maros FERENCIK ; Ming-Yen NG ; Liang ZHONG ; Mona BHATIA ; Akira KURATA ; Pannipa SUWANNASOM ; Yung-Liang WAN ; Trang Ngoc NGUYEN ; Suyon CHANG ; Sung Mok KIM ; Hwan Seok YONG ; Cherry KIM
Korean Journal of Radiology 2026;27(1):27-33
Coronary CT-derived fractional flow reserve (CT-FFR) is a noninvasive alternative to invasive FFR for assessing the hemodynamic significance of coronary artery stenosis. CT-FFR uses routinely acquired coronary CT angiography (CCTA) with artificial intelligence and computational fluid dynamics to estimate pressure gradients, thereby supporting clinical decisionmaking without procedural risk. Adoption and implementation vary widely across regions. In Asia, South Korea exclusively uses HeartMedi+, which enables rapid analysis, streamlined workflow integration, and high user satisfaction. Japan relies primarily on FFR CT, which has national reimbursement and significantly influences treatment strategies, reducing unnecessary invasive procedures. Hong Kong, Singapore, Taiwan, Thailand, and Vietnam remain in early or exploratory phases due to cost, reimbursement, and infrastructure barriers. In the United States, CT-FFR is guideline-endorsed and reimbursed, where HeartFlow is the most widely used, supported by robust clinical validation and outcome data. Despite regional variability, CTFFR offers a noninvasive solution that enhances patient management, reduces unnecessary invasive testing, and is poised for broader clinical integration as technology and validation advance.
2.Upper Airway Collapsibility During Rapid Eye Movement Sleep Is Associated With the Response to Upper Airway Surgery for Obstructive Sleep Apnea
Yung-An TSOU ; Liang-Wen HANG ; Eysteinn FINNSSON ; Jón S. ÁGÚSTSSON ; Scott A. SANDS ; Wan-Ju CHENG
Clinical and Experimental Otorhinolaryngology 2025;18(1):50-56
Objectives:
. Endotype-based interventions have shown promise in the treatment of patients with obstructive sleep apnea, and upper airway surgery is a key therapeutic option. However, responses to surgery vary among patients with obstructive sleep apnea. This study aims to examine changes in endotypic traits following upper airway surgery and to explore their association with surgical outcomes.
Methods:
. We prospectively recruited 25 patients with obstructive sleep apnea who visited a single sleep center for upper airway surgery. These patients underwent polysomnographic studies both before and after surgical intervention. During non-rapid eye movement and rapid eye movement sleep, we estimated endotypic traits—including collapsibility (Vpassive), arousal threshold, loop gain, and upper airway compensation—with the phenotyping using polysomnography method. Based on improvements in the apnea-hypopnea index, patients were classified as either responders or non-responders. We compared the preoperative endotypic traits between these groups using Mann-Whitney tests. Additionally, we compared changes in endotypic traits pre- and post-surgery between responders and non-responders using generalized linear mixed models.
Results:
. We identified 12 responders and 13 non-responders. Compared to non-responders, responders exhibited improved collapsibility during rapid eye movement sleep (22.3 vs. −8.2%eupnea in Vpassive, P=0.01), and their arousal threshold decreased during non-rapid eye movement sleep (−22.4%eupnea, P=0.02). No endotypic trait predicted surgical response; however, the apnea-hypopnea index during rapid eye movement sleep was higher among responders than non-responders (51.8/hr vs. 34.4/hr, P=0.05).
Conclusion
. Upper airway surgery significantly reduced collapsibility during rapid eye movement sleep in responders. The target pathology for upper airway surgery is a compromised upper airway during rapid eye movement sleep.
3.Upper Airway Collapsibility During Rapid Eye Movement Sleep Is Associated With the Response to Upper Airway Surgery for Obstructive Sleep Apnea
Yung-An TSOU ; Liang-Wen HANG ; Eysteinn FINNSSON ; Jón S. ÁGÚSTSSON ; Scott A. SANDS ; Wan-Ju CHENG
Clinical and Experimental Otorhinolaryngology 2025;18(1):50-56
Objectives:
. Endotype-based interventions have shown promise in the treatment of patients with obstructive sleep apnea, and upper airway surgery is a key therapeutic option. However, responses to surgery vary among patients with obstructive sleep apnea. This study aims to examine changes in endotypic traits following upper airway surgery and to explore their association with surgical outcomes.
Methods:
. We prospectively recruited 25 patients with obstructive sleep apnea who visited a single sleep center for upper airway surgery. These patients underwent polysomnographic studies both before and after surgical intervention. During non-rapid eye movement and rapid eye movement sleep, we estimated endotypic traits—including collapsibility (Vpassive), arousal threshold, loop gain, and upper airway compensation—with the phenotyping using polysomnography method. Based on improvements in the apnea-hypopnea index, patients were classified as either responders or non-responders. We compared the preoperative endotypic traits between these groups using Mann-Whitney tests. Additionally, we compared changes in endotypic traits pre- and post-surgery between responders and non-responders using generalized linear mixed models.
Results:
. We identified 12 responders and 13 non-responders. Compared to non-responders, responders exhibited improved collapsibility during rapid eye movement sleep (22.3 vs. −8.2%eupnea in Vpassive, P=0.01), and their arousal threshold decreased during non-rapid eye movement sleep (−22.4%eupnea, P=0.02). No endotypic trait predicted surgical response; however, the apnea-hypopnea index during rapid eye movement sleep was higher among responders than non-responders (51.8/hr vs. 34.4/hr, P=0.05).
Conclusion
. Upper airway surgery significantly reduced collapsibility during rapid eye movement sleep in responders. The target pathology for upper airway surgery is a compromised upper airway during rapid eye movement sleep.
4.Upper Airway Collapsibility During Rapid Eye Movement Sleep Is Associated With the Response to Upper Airway Surgery for Obstructive Sleep Apnea
Yung-An TSOU ; Liang-Wen HANG ; Eysteinn FINNSSON ; Jón S. ÁGÚSTSSON ; Scott A. SANDS ; Wan-Ju CHENG
Clinical and Experimental Otorhinolaryngology 2025;18(1):50-56
Objectives:
. Endotype-based interventions have shown promise in the treatment of patients with obstructive sleep apnea, and upper airway surgery is a key therapeutic option. However, responses to surgery vary among patients with obstructive sleep apnea. This study aims to examine changes in endotypic traits following upper airway surgery and to explore their association with surgical outcomes.
Methods:
. We prospectively recruited 25 patients with obstructive sleep apnea who visited a single sleep center for upper airway surgery. These patients underwent polysomnographic studies both before and after surgical intervention. During non-rapid eye movement and rapid eye movement sleep, we estimated endotypic traits—including collapsibility (Vpassive), arousal threshold, loop gain, and upper airway compensation—with the phenotyping using polysomnography method. Based on improvements in the apnea-hypopnea index, patients were classified as either responders or non-responders. We compared the preoperative endotypic traits between these groups using Mann-Whitney tests. Additionally, we compared changes in endotypic traits pre- and post-surgery between responders and non-responders using generalized linear mixed models.
Results:
. We identified 12 responders and 13 non-responders. Compared to non-responders, responders exhibited improved collapsibility during rapid eye movement sleep (22.3 vs. −8.2%eupnea in Vpassive, P=0.01), and their arousal threshold decreased during non-rapid eye movement sleep (−22.4%eupnea, P=0.02). No endotypic trait predicted surgical response; however, the apnea-hypopnea index during rapid eye movement sleep was higher among responders than non-responders (51.8/hr vs. 34.4/hr, P=0.05).
Conclusion
. Upper airway surgery significantly reduced collapsibility during rapid eye movement sleep in responders. The target pathology for upper airway surgery is a compromised upper airway during rapid eye movement sleep.
5.Ultrasonography of acute retroperitoneum
Hung-Hsien LIU ; Yenpo LIN ; Gigin LIN ; Li-Jen WANG ; Yung-Liang WAN
Ultrasonography 2024;43(3):179-192
The retroperitoneum is an important space in the human body that is often implicated in a range Epub ahead of print of acute medical conditions, some of which can be life-threatening. Ultrasonography may serve as a pivotal first-line imaging technique when assessing patients with suspected retroperitoneal abnormalities. Effective ultrasonography of the retroperitoneum requires a comprehensive grasp of its anatomy, adjacent structures, and potential pathologies. Being well-acquainted with the imaging characteristics of acute conditions can meaningfully assist in an accurate diagnosis and guide subsequent management. This review article summarizes and illustrates the acute conditions involving the retroperitoneum through the lens of ultrasound imaging.
6.Ultrasonography of acute retroperitoneum
Hung-Hsien LIU ; Yenpo LIN ; Gigin LIN ; Li-Jen WANG ; Yung-Liang WAN
Ultrasonography 2024;43(3):179-192
The retroperitoneum is an important space in the human body that is often implicated in a range Epub ahead of print of acute medical conditions, some of which can be life-threatening. Ultrasonography may serve as a pivotal first-line imaging technique when assessing patients with suspected retroperitoneal abnormalities. Effective ultrasonography of the retroperitoneum requires a comprehensive grasp of its anatomy, adjacent structures, and potential pathologies. Being well-acquainted with the imaging characteristics of acute conditions can meaningfully assist in an accurate diagnosis and guide subsequent management. This review article summarizes and illustrates the acute conditions involving the retroperitoneum through the lens of ultrasound imaging.
7.Ultrasonography of acute retroperitoneum
Hung-Hsien LIU ; Yenpo LIN ; Gigin LIN ; Li-Jen WANG ; Yung-Liang WAN
Ultrasonography 2024;43(3):179-192
The retroperitoneum is an important space in the human body that is often implicated in a range Epub ahead of print of acute medical conditions, some of which can be life-threatening. Ultrasonography may serve as a pivotal first-line imaging technique when assessing patients with suspected retroperitoneal abnormalities. Effective ultrasonography of the retroperitoneum requires a comprehensive grasp of its anatomy, adjacent structures, and potential pathologies. Being well-acquainted with the imaging characteristics of acute conditions can meaningfully assist in an accurate diagnosis and guide subsequent management. This review article summarizes and illustrates the acute conditions involving the retroperitoneum through the lens of ultrasound imaging.
8.Ultrasonography of acute retroperitoneum
Hung-Hsien LIU ; Yenpo LIN ; Gigin LIN ; Li-Jen WANG ; Yung-Liang WAN
Ultrasonography 2024;43(3):179-192
The retroperitoneum is an important space in the human body that is often implicated in a range Epub ahead of print of acute medical conditions, some of which can be life-threatening. Ultrasonography may serve as a pivotal first-line imaging technique when assessing patients with suspected retroperitoneal abnormalities. Effective ultrasonography of the retroperitoneum requires a comprehensive grasp of its anatomy, adjacent structures, and potential pathologies. Being well-acquainted with the imaging characteristics of acute conditions can meaningfully assist in an accurate diagnosis and guide subsequent management. This review article summarizes and illustrates the acute conditions involving the retroperitoneum through the lens of ultrasound imaging.
9.Hyperpolarized Carbon-13 Magnetic Resonance Imaging:Technical Considerations and Clinical Applications
Ying-Chieh LAI ; Ching-Yi HSIEH ; Yu-Hsiang JUAN ; Kuan-Ying LU ; Hsien-Ju LEE ; Shu-Hang NG ; Yung-Liang WAN ; Gigin LIN
Korean Journal of Radiology 2024;25(5):459-472
Hyperpolarized (HP) carbon-13 ( 13C) MRI represents an innovative approach for noninvasive, real-time assessment of dynamic metabolic flux, with potential integration into routine clinical MRI. The use of [1- 13C]pyruvate as a probe and its conversion to [1- 13C]lactate constitute an extensively explored metabolic pathway. This review comprehensively outlines the establishment of HP 13C-MRI, covering multidisciplinary team collaboration, hardware prerequisites, probe preparation, hyperpolarization techniques, imaging acquisition, and data analysis. This article discusses the clinical applications of HP 13C-MRI across various anatomical domains, including the brain, heart, skeletal muscle, breast, liver, kidney, pancreas, andprostate. Each section highlights the specific applications and findings pertinent to these regions, emphasizing the potential versatility of HP 13C-MRI in diverse clinical contexts. This review serves as a comprehensive update, bridging technical aspects with clinical applications and offering insights into the ongoing advancements in HP 13C-MRI.
10.Ultrasonography of acute retroperitoneum
Hung-Hsien LIU ; Yenpo LIN ; Gigin LIN ; Li-Jen WANG ; Yung-Liang WAN
Ultrasonography 2024;43(3):179-192
The retroperitoneum is an important space in the human body that is often implicated in a range Epub ahead of print of acute medical conditions, some of which can be life-threatening. Ultrasonography may serve as a pivotal first-line imaging technique when assessing patients with suspected retroperitoneal abnormalities. Effective ultrasonography of the retroperitoneum requires a comprehensive grasp of its anatomy, adjacent structures, and potential pathologies. Being well-acquainted with the imaging characteristics of acute conditions can meaningfully assist in an accurate diagnosis and guide subsequent management. This review article summarizes and illustrates the acute conditions involving the retroperitoneum through the lens of ultrasound imaging.

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