1.Anti-Inflammatory Activity of Cell-Penetrating Peptide Nucleic Acids Targeting Indoleamine 2,3-Dioxygenase 1 in IFNγ-Treated Human Keratinocytes
Daram JUNG ; Sungjin AHN ; In Guk PARK ; Yeasel JEON ; Sangbong LEE ; Minsoo NOH
Biomolecules & Therapeutics 2025;33(3):494-500
Indoleamine 2,3-dioxygenase 1 (IDO1) is an enzyme that plays a pivotal role in immune regulation by metabolizing tryptophan into kynurenine, leading to T cell suppression and promoting immune tolerance. However, persistent activation of IDO1 can lead to prolonged immune stimulation in inflammatory conditions such as skin diseases and chronic inflammation. In this study, we developed modified peptide nucleic acids (PNAs) conjugated with cationic lipid chains to target IDO1 pre-mRNA and evaluated their anti-inflammatory effects in human keratinocytes. The modified PNAs demonstrated enhanced solubility, robust binding affinity, and effective penetration into keratinocytes. Quantitative PCR results showed significant downregulation of IDO1 and pro-inflammatory cytokines such as IL-6, IL-8, and PTGS2 in interferon γ (IFNγ)-treated keratinocytes. These findings suggest that cell-penetrating PNAs targeting IDO1 hold potential as a therapeutic approach for inflammatory skin disorders and chronic inflammation.
2.Deep Learning-Accelerated Non-Contrast Abbreviated Liver MRI for Detecting Malignant Focal Hepatic Lesions: Dual-Center Validation
So Hyun PARK ; Moon Hyung CHOI ; Bohyun KIM ; Hyun-Soo LEE ; Sungjin YOON ; Young Joon LEE ; Dominik NICKEL ; Thomas BENKERT
Korean Journal of Radiology 2025;26(4):333-345
Objective:
To compare a deep learning (DL)-accelerated non-enhanced abbreviated MRI (AMRI DL) protocol with standard AMRI (AMRI STD) of the liver in terms of image quality and malignant focal lesion detection.
Materials and Methods:
This retrospective study included 155 consecutive patients (110 male; mean age 62.4 ± 11 years) from two sites who underwent standard liver MRI and additional AMRIDL sequences, specifically DL-accelerated single-shot fast-spin echo (SSFSE DL) and DL-accelerated diffusion-weighted imaging (DWIDL). Additional MRI phantom experiments assessed signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and apparent diffusion coefficient (ADC) values. Three reviewers evaluated AMRIDL and AMRI STD protocols for image quality using a five-point Likert scale and identified malignant hepatic lesions. Image quality scores and per-lesion sensitivities were compared between AMRIDL and AMRI STD using the Wilcoxon signed-rank test and logistic regression with generalized estimating equations, respectively.
Results:
Phantom experiments demonstrated comparable SNR and higher CNR for SSFSE DL compared to SSFSE STD, with similar ADC values for DWIDL and DWI STD. Among the 155 patients, 130 (83.9%) had chronic liver disease or a history of intra- or extrahepatic malignancy. Of 104 malignant focal lesions in 64 patients, 58 (55.8%) were hepatocellular carcinomas (HCCs), 38 (36.5%) were metastases, four (3.8%) were cholangiocarcinomas, and four (3.8%) were lymphomas. The pooled per-lesion sensitivity across three readers was 97.6% for AMRIDL, comparable to 97.6% for AMRI STD. Compared with AMRI STD, AMRIDL demonstrated superior image quality regarding structural sharpness, artifacts, and noise (all P < 0.001) and reduced the average scan time by approximately 50% (2 min 29 sec vs. 4 min 11 sec). In patients with chronic liver disease, AMRIDL achieved a 96.6% per-lesion sensitivity for HCC detection, similar to 96.5% for AMRI STD (P > 0.05).
Conclusion
The AMRIDL protocol offers comparable sensitivity for detecting malignant focal lesions, including HCC while significantly enhancing image quality and reducing scan time by approximately 50% compared to AMRI STD.
3.Deep Learning-Accelerated Non-Contrast Abbreviated Liver MRI for Detecting Malignant Focal Hepatic Lesions: Dual-Center Validation
So Hyun PARK ; Moon Hyung CHOI ; Bohyun KIM ; Hyun-Soo LEE ; Sungjin YOON ; Young Joon LEE ; Dominik NICKEL ; Thomas BENKERT
Korean Journal of Radiology 2025;26(4):333-345
Objective:
To compare a deep learning (DL)-accelerated non-enhanced abbreviated MRI (AMRI DL) protocol with standard AMRI (AMRI STD) of the liver in terms of image quality and malignant focal lesion detection.
Materials and Methods:
This retrospective study included 155 consecutive patients (110 male; mean age 62.4 ± 11 years) from two sites who underwent standard liver MRI and additional AMRIDL sequences, specifically DL-accelerated single-shot fast-spin echo (SSFSE DL) and DL-accelerated diffusion-weighted imaging (DWIDL). Additional MRI phantom experiments assessed signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and apparent diffusion coefficient (ADC) values. Three reviewers evaluated AMRIDL and AMRI STD protocols for image quality using a five-point Likert scale and identified malignant hepatic lesions. Image quality scores and per-lesion sensitivities were compared between AMRIDL and AMRI STD using the Wilcoxon signed-rank test and logistic regression with generalized estimating equations, respectively.
Results:
Phantom experiments demonstrated comparable SNR and higher CNR for SSFSE DL compared to SSFSE STD, with similar ADC values for DWIDL and DWI STD. Among the 155 patients, 130 (83.9%) had chronic liver disease or a history of intra- or extrahepatic malignancy. Of 104 malignant focal lesions in 64 patients, 58 (55.8%) were hepatocellular carcinomas (HCCs), 38 (36.5%) were metastases, four (3.8%) were cholangiocarcinomas, and four (3.8%) were lymphomas. The pooled per-lesion sensitivity across three readers was 97.6% for AMRIDL, comparable to 97.6% for AMRI STD. Compared with AMRI STD, AMRIDL demonstrated superior image quality regarding structural sharpness, artifacts, and noise (all P < 0.001) and reduced the average scan time by approximately 50% (2 min 29 sec vs. 4 min 11 sec). In patients with chronic liver disease, AMRIDL achieved a 96.6% per-lesion sensitivity for HCC detection, similar to 96.5% for AMRI STD (P > 0.05).
Conclusion
The AMRIDL protocol offers comparable sensitivity for detecting malignant focal lesions, including HCC while significantly enhancing image quality and reducing scan time by approximately 50% compared to AMRI STD.
4.Deep Learning-Accelerated Non-Contrast Abbreviated Liver MRI for Detecting Malignant Focal Hepatic Lesions: Dual-Center Validation
So Hyun PARK ; Moon Hyung CHOI ; Bohyun KIM ; Hyun-Soo LEE ; Sungjin YOON ; Young Joon LEE ; Dominik NICKEL ; Thomas BENKERT
Korean Journal of Radiology 2025;26(4):333-345
Objective:
To compare a deep learning (DL)-accelerated non-enhanced abbreviated MRI (AMRI DL) protocol with standard AMRI (AMRI STD) of the liver in terms of image quality and malignant focal lesion detection.
Materials and Methods:
This retrospective study included 155 consecutive patients (110 male; mean age 62.4 ± 11 years) from two sites who underwent standard liver MRI and additional AMRIDL sequences, specifically DL-accelerated single-shot fast-spin echo (SSFSE DL) and DL-accelerated diffusion-weighted imaging (DWIDL). Additional MRI phantom experiments assessed signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and apparent diffusion coefficient (ADC) values. Three reviewers evaluated AMRIDL and AMRI STD protocols for image quality using a five-point Likert scale and identified malignant hepatic lesions. Image quality scores and per-lesion sensitivities were compared between AMRIDL and AMRI STD using the Wilcoxon signed-rank test and logistic regression with generalized estimating equations, respectively.
Results:
Phantom experiments demonstrated comparable SNR and higher CNR for SSFSE DL compared to SSFSE STD, with similar ADC values for DWIDL and DWI STD. Among the 155 patients, 130 (83.9%) had chronic liver disease or a history of intra- or extrahepatic malignancy. Of 104 malignant focal lesions in 64 patients, 58 (55.8%) were hepatocellular carcinomas (HCCs), 38 (36.5%) were metastases, four (3.8%) were cholangiocarcinomas, and four (3.8%) were lymphomas. The pooled per-lesion sensitivity across three readers was 97.6% for AMRIDL, comparable to 97.6% for AMRI STD. Compared with AMRI STD, AMRIDL demonstrated superior image quality regarding structural sharpness, artifacts, and noise (all P < 0.001) and reduced the average scan time by approximately 50% (2 min 29 sec vs. 4 min 11 sec). In patients with chronic liver disease, AMRIDL achieved a 96.6% per-lesion sensitivity for HCC detection, similar to 96.5% for AMRI STD (P > 0.05).
Conclusion
The AMRIDL protocol offers comparable sensitivity for detecting malignant focal lesions, including HCC while significantly enhancing image quality and reducing scan time by approximately 50% compared to AMRI STD.
5.Anti-Inflammatory Activity of Cell-Penetrating Peptide Nucleic Acids Targeting Indoleamine 2,3-Dioxygenase 1 in IFNγ-Treated Human Keratinocytes
Daram JUNG ; Sungjin AHN ; In Guk PARK ; Yeasel JEON ; Sangbong LEE ; Minsoo NOH
Biomolecules & Therapeutics 2025;33(3):494-500
Indoleamine 2,3-dioxygenase 1 (IDO1) is an enzyme that plays a pivotal role in immune regulation by metabolizing tryptophan into kynurenine, leading to T cell suppression and promoting immune tolerance. However, persistent activation of IDO1 can lead to prolonged immune stimulation in inflammatory conditions such as skin diseases and chronic inflammation. In this study, we developed modified peptide nucleic acids (PNAs) conjugated with cationic lipid chains to target IDO1 pre-mRNA and evaluated their anti-inflammatory effects in human keratinocytes. The modified PNAs demonstrated enhanced solubility, robust binding affinity, and effective penetration into keratinocytes. Quantitative PCR results showed significant downregulation of IDO1 and pro-inflammatory cytokines such as IL-6, IL-8, and PTGS2 in interferon γ (IFNγ)-treated keratinocytes. These findings suggest that cell-penetrating PNAs targeting IDO1 hold potential as a therapeutic approach for inflammatory skin disorders and chronic inflammation.
6.Deep Learning-Accelerated Non-Contrast Abbreviated Liver MRI for Detecting Malignant Focal Hepatic Lesions: Dual-Center Validation
So Hyun PARK ; Moon Hyung CHOI ; Bohyun KIM ; Hyun-Soo LEE ; Sungjin YOON ; Young Joon LEE ; Dominik NICKEL ; Thomas BENKERT
Korean Journal of Radiology 2025;26(4):333-345
Objective:
To compare a deep learning (DL)-accelerated non-enhanced abbreviated MRI (AMRI DL) protocol with standard AMRI (AMRI STD) of the liver in terms of image quality and malignant focal lesion detection.
Materials and Methods:
This retrospective study included 155 consecutive patients (110 male; mean age 62.4 ± 11 years) from two sites who underwent standard liver MRI and additional AMRIDL sequences, specifically DL-accelerated single-shot fast-spin echo (SSFSE DL) and DL-accelerated diffusion-weighted imaging (DWIDL). Additional MRI phantom experiments assessed signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and apparent diffusion coefficient (ADC) values. Three reviewers evaluated AMRIDL and AMRI STD protocols for image quality using a five-point Likert scale and identified malignant hepatic lesions. Image quality scores and per-lesion sensitivities were compared between AMRIDL and AMRI STD using the Wilcoxon signed-rank test and logistic regression with generalized estimating equations, respectively.
Results:
Phantom experiments demonstrated comparable SNR and higher CNR for SSFSE DL compared to SSFSE STD, with similar ADC values for DWIDL and DWI STD. Among the 155 patients, 130 (83.9%) had chronic liver disease or a history of intra- or extrahepatic malignancy. Of 104 malignant focal lesions in 64 patients, 58 (55.8%) were hepatocellular carcinomas (HCCs), 38 (36.5%) were metastases, four (3.8%) were cholangiocarcinomas, and four (3.8%) were lymphomas. The pooled per-lesion sensitivity across three readers was 97.6% for AMRIDL, comparable to 97.6% for AMRI STD. Compared with AMRI STD, AMRIDL demonstrated superior image quality regarding structural sharpness, artifacts, and noise (all P < 0.001) and reduced the average scan time by approximately 50% (2 min 29 sec vs. 4 min 11 sec). In patients with chronic liver disease, AMRIDL achieved a 96.6% per-lesion sensitivity for HCC detection, similar to 96.5% for AMRI STD (P > 0.05).
Conclusion
The AMRIDL protocol offers comparable sensitivity for detecting malignant focal lesions, including HCC while significantly enhancing image quality and reducing scan time by approximately 50% compared to AMRI STD.
7.Anti-Inflammatory Activity of Cell-Penetrating Peptide Nucleic Acids Targeting Indoleamine 2,3-Dioxygenase 1 in IFNγ-Treated Human Keratinocytes
Daram JUNG ; Sungjin AHN ; In Guk PARK ; Yeasel JEON ; Sangbong LEE ; Minsoo NOH
Biomolecules & Therapeutics 2025;33(3):494-500
Indoleamine 2,3-dioxygenase 1 (IDO1) is an enzyme that plays a pivotal role in immune regulation by metabolizing tryptophan into kynurenine, leading to T cell suppression and promoting immune tolerance. However, persistent activation of IDO1 can lead to prolonged immune stimulation in inflammatory conditions such as skin diseases and chronic inflammation. In this study, we developed modified peptide nucleic acids (PNAs) conjugated with cationic lipid chains to target IDO1 pre-mRNA and evaluated their anti-inflammatory effects in human keratinocytes. The modified PNAs demonstrated enhanced solubility, robust binding affinity, and effective penetration into keratinocytes. Quantitative PCR results showed significant downregulation of IDO1 and pro-inflammatory cytokines such as IL-6, IL-8, and PTGS2 in interferon γ (IFNγ)-treated keratinocytes. These findings suggest that cell-penetrating PNAs targeting IDO1 hold potential as a therapeutic approach for inflammatory skin disorders and chronic inflammation.
8.Deep Learning-Accelerated Non-Contrast Abbreviated Liver MRI for Detecting Malignant Focal Hepatic Lesions: Dual-Center Validation
So Hyun PARK ; Moon Hyung CHOI ; Bohyun KIM ; Hyun-Soo LEE ; Sungjin YOON ; Young Joon LEE ; Dominik NICKEL ; Thomas BENKERT
Korean Journal of Radiology 2025;26(4):333-345
Objective:
To compare a deep learning (DL)-accelerated non-enhanced abbreviated MRI (AMRI DL) protocol with standard AMRI (AMRI STD) of the liver in terms of image quality and malignant focal lesion detection.
Materials and Methods:
This retrospective study included 155 consecutive patients (110 male; mean age 62.4 ± 11 years) from two sites who underwent standard liver MRI and additional AMRIDL sequences, specifically DL-accelerated single-shot fast-spin echo (SSFSE DL) and DL-accelerated diffusion-weighted imaging (DWIDL). Additional MRI phantom experiments assessed signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and apparent diffusion coefficient (ADC) values. Three reviewers evaluated AMRIDL and AMRI STD protocols for image quality using a five-point Likert scale and identified malignant hepatic lesions. Image quality scores and per-lesion sensitivities were compared between AMRIDL and AMRI STD using the Wilcoxon signed-rank test and logistic regression with generalized estimating equations, respectively.
Results:
Phantom experiments demonstrated comparable SNR and higher CNR for SSFSE DL compared to SSFSE STD, with similar ADC values for DWIDL and DWI STD. Among the 155 patients, 130 (83.9%) had chronic liver disease or a history of intra- or extrahepatic malignancy. Of 104 malignant focal lesions in 64 patients, 58 (55.8%) were hepatocellular carcinomas (HCCs), 38 (36.5%) were metastases, four (3.8%) were cholangiocarcinomas, and four (3.8%) were lymphomas. The pooled per-lesion sensitivity across three readers was 97.6% for AMRIDL, comparable to 97.6% for AMRI STD. Compared with AMRI STD, AMRIDL demonstrated superior image quality regarding structural sharpness, artifacts, and noise (all P < 0.001) and reduced the average scan time by approximately 50% (2 min 29 sec vs. 4 min 11 sec). In patients with chronic liver disease, AMRIDL achieved a 96.6% per-lesion sensitivity for HCC detection, similar to 96.5% for AMRI STD (P > 0.05).
Conclusion
The AMRIDL protocol offers comparable sensitivity for detecting malignant focal lesions, including HCC while significantly enhancing image quality and reducing scan time by approximately 50% compared to AMRI STD.
9.Advanced Abdominal MRI Techniques and Problem-Solving Strategies
Yoonhee LEE ; Sungjin YOON ; So Hyun PARK ; Marcel Dominik NICKEL
Journal of the Korean Society of Radiology 2024;85(2):345-362
MRI plays an important role in abdominal imaging because of its ability to detect and characterize focal lesions. However, MRI examinations have several challenges, such as comparatively long scan times and motion management through breath-holding maneuvers. Techniques for reducing scan time with acceptable image quality, such as parallel imaging, compressed sensing, and cutting-edge deep learning techniques, have been developed to enable problem-solving strategies. Additionally, free-breathing techniques for dynamic contrast-enhanced imaging, such as extra-dimensional-volumetric interpolated breath-hold examination, golden-angle radial sparse parallel, and liver acceleration volume acquisition Star, can help patients with severe dyspnea or those under sedation to undergo abdominal MRI. We aimed to present various advanced abdominal MRI techniques for reducing the scan time while maintaining image quality and free-breathing techniques for dynamic imaging and illustrate cases using the techniques mentioned above. A review of these advanced techniques can assist in the appropriate interpretation of sequences.
10.Cellular Plasticity in Gut and Liver Regeneration
Minwook KIM ; Yoojeong PARK ; You Sun KIM ; Sungjin KO
Gut and Liver 2024;18(6):949-960
The intestine and liver share a unique regenerative property that sets them apart from other mammalian visceral organs. The intestinal epithelium exhibits rapid renewal, making it one of the fastest renewing tissues in humans. Under physiological conditions, intestinal stem cells within each intestinal crypt continuously differentiate into the different types of intestinal epithelial cells to maintain intestinal homeostasis. However, when exposed to tissue damage or stressful conditions such as inflammation, intestinal epithelial cells in the gastrointestinal tract exhibit plasticity, allowing fully differentiated cells to regain their stem cell properties. Likewise, hepatic epithelial cells possess a remarkable regenerative capacity to restore lost liver mass through proliferationmediated liver regeneration. When the proliferation-mediated regenerative capacity is impaired, hepatocytes and biliary epithelial cells (BECs) can undergo plasticity-mediated regeneration and replenish each other. The transition of mammalian liver progenitor cells to hepatocytes/BECs can be observed under tightly controlled experimental conditions such as severe hepatocyte injury accompanied by the loss of regenerative capacity. In this review, we will discuss the mechanism by which cellular plasticity contributes to the regeneration process and the potential therapeutic implications of understanding and harnessing cellular plasticity in the gut and liver.

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