Publications by authors named "Seong Ho Park"

321 Publications

CycleMorph: Cycle consistent unsupervised deformable image registration.

Med Image Anal 2021 Mar 12;71:102036. Epub 2021 Mar 12.

Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea. Electronic address:

Image registration is a fundamental task in medical image analysis. Recently, many deep learning based image registration methods have been extensively investigated due to their comparable performance with the state-of-the-art classical approaches despite the ultra-fast computational time. However, the existing deep learning methods still have limitations in the preservation of original topology during the deformation with registration vector fields. To address this issues, here we present a cycle-consistent deformable image registration, dubbed CycleMorph. The cycle consistency enhances image registration performance by providing an implicit regularization to preserve topology during the deformation. The proposed method is so flexible that it can beapplied for both 2D and 3D registration problems for various applications, and can be easily extended to multi-scale implementation to deal with the memory issues in large volume registration. Experimental results on various datasets from medical and non-medical applications demonstrate that the proposed method provides effective and accurate registration on diverse image pairs within a few seconds. Qualitative and quantitative evaluations on deformation fields also verify the effectiveness of the cycle consistency of the proposed method.
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http://dx.doi.org/10.1016/j.media.2021.102036DOI Listing
March 2021

CReVIS-Seq: A highly accurate and multiplexable method for genome-wide mapping of lentiviral integration sites.

Mol Ther Methods Clin Dev 2021 Mar 11;20:792-800. Epub 2021 Jan 11.

Department of Genetics, College of Medicine, Hanyang University, Seoul 04763, South Korea.

Lentiviruses have been widely used as a means of transferring exogenous DNAs into human cells to treat various genetic diseases. Lentiviral vectors are fundamentally integrated into the host genome, but their integration sites are generally unpredictable, which may increase the uncertainty for their use in therapeutics. To determine the viral integration sites in the host genome, several PCR-based methods have been developed. However, the sensitivities of the PCR-based methods are highly dependent on the primer sequences, and optimized primer design is required for individual target sites. In order to address this issue, we developed an alternative method for genome-wide mapping of viral insertion sites, named CReVIS-seq (CRISPR-enhanced Viral Integration Site Sequencing). The method is based on the sequential steps: fragmentation of genomic DNAs, circularization, cleavage of target sequence in a CRISPR guide RNA-specific manner, high-throughput sequencing of the linearized DNA fragments in an unbiased manner, and identification of viral insertion sites via sequence analysis. By design, CReVIS-seq is not affected by biases that could be introduced during the target enrichment step via PCR amplification using site specific primers. Furthermore, we found that multiplexed CReVIS-seq, using collections of different single-guide RNAs (sgRNAs), enables simultaneous identification of multiple target sites and structural variations (i.e., circularized viral genome), in both single cell clones and heterogeneous cell populations.
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http://dx.doi.org/10.1016/j.omtm.2020.10.012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7961857PMC
March 2021

Deep learning-based algorithm to detect primary hepatic malignancy in multiphase CT of patients at high risk for HCC.

Eur Radiol 2021 Mar 18. Epub 2021 Mar 18.

Department of Convergence Medicine, Asan Medical Institute of Convergence Science and Technology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.

Objectives: To develop and evaluate a deep learning-based model capable of detecting primary hepatic malignancies in multiphase CT images of patients at high risk for hepatocellular carcinoma (HCC).

Methods: A total of 1350 multiphase CT scans of 1280 hepatic malignancies (1202 HCCs and 78 non-HCCs) in 1320 patients at high risk for HCC were retrospectively analyzed. Following the delineation of the focal hepatic lesions according to reference standards, the CT scans were categorized randomly into the training (568 scans), tuning (193 scans), and test (589 scans) sets. Multiphase CT information was subjected to multichannel integration, and livers were automatically segmented before model development. A deep learning-based model capable of detecting malignancies was developed using a mask region-based convolutional neural network. The thresholds of the prediction score and the intersection over union were determined on the tuning set corresponding to the highest sensitivity with < 5 false-positive cases per CT scan. The sensitivity and the number of false-positives of the proposed model on the test set were calculated. Potential causes of false-negatives and false-positives on the test set were analyzed.

Results: This model exhibited a sensitivity of 84.8% with 4.80 false-positives per CT scan on the test set. The most frequent potential causes of false-negatives and false-positives were determined to be atypical enhancement patterns for HCC (71.7%) and registration/segmentation errors (42.7%), respectively.

Conclusions: The proposed deep learning-based model developed to automatically detect primary hepatic malignancies exhibited an 84.8% of sensitivity with 4.80 false-positives per CT scan in the test set.

Key Points: • Image processing, including multichannel integration of multiphase CT and automatic liver segmentation, enabled the application of a deep learning-based model to detect primary hepatic malignancy. • Our model exhibited a sensitivity of 84.8% with a false-positive rate of 4.80 per CT scan.
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http://dx.doi.org/10.1007/s00330-021-07803-2DOI Listing
March 2021

Complete intersphincteric longitudinal muscle excision May Be key to reducing local recurrence during intersphincteric resection.

Eur J Surg Oncol 2021 Jan 5. Epub 2021 Jan 5.

Department of Radiology, University of Ulsan College of Medicine and Asan Medical Center, Seoul, 05505, Republic of Korea.

Background: Although total mesorectal excision (TME) is regarded as a standard procedure for rectal cancer, technical definition and evaluation method have not yet been investigated for intersphincteric resection (ISR). This study was performed to introduce a complete ISR procedure, and to assess whether total intersphincteric longitudinal muscle excision (TILME) facilitated the completeness of ISR and reduced recurrence.

Methods: A total of 1080 patients with rectal adenocarcinoma who underwent robot-assisted low anterior resection (LAR) over 10 years were consecutively enrolled. Propensity-score matching of the two LAR groups (ISR vs LAR group, 1:1) and three ISR subgroups (partial vs subtotal vs total ISR subgroup, 2:2:1) was performed by strict adjustment of baseline characteristics. Archived specimens and video-/photo-records were reevaluated to examine completeness of TILME.

Results: Complete-TILME was performed in 84.5% of patients who underwent ISR. Multivariate analysis showed that incomplete-TILME was the only parameter independently associated with increased 5-year cumulative local recurrence (odds ratio = 23.385; 95% confidence interval = 1.492-366.421; p = 0.03), and that incomplete-TILME was independently associated with adipose tissue surrounding the intersphincteric longitudinal muscle, coloanal anastomosis, and total ISR (p < 0.001-0.05). Although mean incontinence scores and anorectal manometry deteriorated to some degree 12-24 months after surgery in all patients, they remained acceptable. The 5-year cumulative DFS (74.1% vs 60%, p = 0.18) and OS (85.9% vs 70%, p = 0.10) rates tended to be higher in patients with complete than incomplete-TILME.

Conclusions: The completeness of TILME appears to be an independent indicator of complete ISR, reducing local recurrence following lower rectal cancer surgery.
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http://dx.doi.org/10.1016/j.ejso.2020.12.017DOI Listing
January 2021

Key Principles of Clinical Validation, Device Approval, and Insurance Coverage Decisions of Artificial Intelligence.

Korean J Radiol 2021 03;22(3):442-453

Department of Gastroenterology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.

Artificial intelligence (AI) will likely affect various fields of medicine. This article aims to explain the fundamental principles of clinical validation, device approval, and insurance coverage decisions of AI algorithms for medical diagnosis and prediction. Discrimination accuracy of AI algorithms is often evaluated with the Dice similarity coefficient, sensitivity, specificity, and traditional or free-response receiver operating characteristic curves. Calibration accuracy should also be assessed, especially for algorithms that provide probabilities to users. As current AI algorithms have limited generalizability to real-world practice, clinical validation of AI should put it to proper external testing and assisting roles. External testing could adopt diagnostic case-control or diagnostic cohort designs. A diagnostic case-control study evaluates the technical validity/accuracy of AI while the latter tests the clinical validity/accuracy of AI in samples representing target patients in real-world clinical scenarios. Ultimate clinical validation of AI requires evaluations of its impact on patient outcomes, referred to as clinical utility, and for which randomized clinical trials are ideal. Device approval of AI is typically granted with proof of technical validity/accuracy and thus does not intend to directly indicate if AI is beneficial for patient care or if it improves patient outcomes. Neither can it categorically address the issue of limited generalizability of AI. After achieving device approval, it is up to medical professionals to determine if the approved AI algorithms are beneficial for real-world patient care. Insurance coverage decisions generally require a demonstration of clinical utility that the use of AI has improved patient outcomes.
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http://dx.doi.org/10.3348/kjr.2021.0048DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7909857PMC
March 2021

Surgical Outcomes and Survival Prognostic Factors for Palliative Gastrectomies in Stage IV Resectable Gastric Cancer Outlet Obstruction Patients.

J Gastric Cancer 2020 Dec 23;20(4):421-430. Epub 2020 Dec 23.

Department of Surgery, Hanyang University Guri Hospital, Hanyang University School of Medicine, Seoul, Korea.

Purpose: Currently, there is no clear evidence to support any specific treatment as a principal therapy for stage IV gastric cancer outlet obstruction (GCOO) patients. This study evaluated the outcomes of palliative gastrectomies and survival prognostic factors in patients with stage IV resectable GCOO.

Materials And Methods: We retrospectively reviewed the medical records of 48 stage IV GCOO patients who underwent palliative gastrectomies between June 2010 and December 2019. Palliative gastrectomies were performed only in patients with resectable disease. Early surgical outcomes and prognostic factors were analyzed using univariate and multivariate analyses.

Results: There were no specific risk factors for postoperative complications, except for being underweight. Severe postoperative complications developed in five patients, and most of the patients underwent interventional procedures and received broad-spectrum antibiotics for intra-abdominal abscesses. The multivariate survival analysis showed that palliative chemotherapy is a positive prognostic factor, while the specific type of hematogenous and lymphatic metastasis is a negative prognostic factor.

Conclusions: We recommend that the treatment method for stage IV GCOO should be selected according to each patient's physical condition and tumor characteristics. In addition, we suggest that palliative gastrectomies can be performed in stage IV resectable GCOO patients without unfavorable prognostic factors (types of hematogenous and lymphatic metastases).
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http://dx.doi.org/10.5230/jgc.2020.20.e34DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7781751PMC
December 2020

What's New in the of Radiology in 2021.

Authors:
Seong Ho Park

Korean J Radiol 2021 01;22(1):1-4

Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.

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http://dx.doi.org/10.3348/kjr.2020.1429DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7772385PMC
January 2021

Artificial intelligence for ultrasonography: unique opportunities and challenges.

Authors:
Seong Ho Park

Ultrasonography 2021 Jan 3;40(1):3-6. Epub 2020 Nov 3.

Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro 43-gil, Songpa-gu, Seoul 05505, Korea.

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http://dx.doi.org/10.14366/usg.20078DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7758099PMC
January 2021

Accuracy of contrast-enhanced ultrasound liver imaging reporting and data system: a systematic review and meta-analysis.

Hepatol Int 2020 Dec 10;14(6):1104-1113. Epub 2020 Nov 10.

Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 88, Olympic-ro 43-gil, Songpa-gu, Seoul, 05505, South Korea.

Background And Aim: After the introduction of the contrast-enhanced ultrasound Liver Imaging Reporting and Data System (CEUS LI-RADS), several studies have reported on its performance, but the reported data vary considerably. Therefore, we performed a systematic review and meta-analysis to determine the diagnostic performance of CEUS LI-RADS in patients at risk for hepatocellular carcinoma (HCC) and investigate the causes of study heterogeneity.

Methods: Original studies published until May 30, 2020, investigating the diagnostic performance of CEUS LI-RADS were identified in the MEDLINE, EMBASE, and Cochrane library databases. Study quality was assessed using the QUADAS-2 tool. Meta-analytic summary sensitivity and specificity for the diagnosis of HCC were calculated using a bivariate random-effects model. Meta-regression analysis was performed to explore the causes of study heterogeneity.

Results: Of the 105 articles screened, eight studies were finally analyzed (5428 hepatic observations). The summary sensitivity and specificity of CEUS LI-RADS category 5 (LR-5) for diagnosing HCC were 73% [95% confidence interval (CI) 65-79%; I = 93%] and 95% (95% CI 91-97%; I = 89%), respectively. Substantial study heterogeneity was noted in both sensitivity and specificity. Study heterogeneity was significantly associated with the proportion of cases of HCC and the type of reference standard (p ≤ 0.05).

Conclusion: CEUS LI-RADS had high pooled specificity for diagnosing HCC but suboptimal pooled sensitivity. Substantial study heterogeneity was found, which was significantly associated with the proportion of cases of HCC and the type of reference standard.
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http://dx.doi.org/10.1007/s12072-020-10102-5DOI Listing
December 2020

A Single-Center Retrospective Analysis of Periprocedural Variables Affecting Local Tumor Progression after Radiofrequency Ablation of Colorectal Cancer Liver Metastases.

Radiology 2021 01 10;298(1):212-218. Epub 2020 Nov 10.

From the Department of Radiology, Severance Hospital, Research Institute of Radiological Science (K.H.), and Biostatistics Collaboration Unit, Department of Biomedical Systems Informatics (M.L.), Yonsei University College of Medicine, Seoul, Korea; and Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro, 43-gil, Songpa-gu, Seoul, 138-736, Korea (J.H.K., S.G.Y., S.H.P., H.K.C., S.Y.C., P.N.K., J.P.).

Background Local tumor progression (LTP) is associated with poorer survival in patients undergoing radiofrequency ablation (RFA) for colorectal liver metastasis (CLM). An algorithmic strategy to predict LTP may help in selection of patients who would benefit most from RFA for CLM. Purpose To estimate local tumor progression-free survival (LTPFS) following RFA of CLM and develop an algorithmic strategy based on clinical variables. Materials and Methods In this retrospective study, between March 2000 and December 2014, patients who underwent percutaneous RFA for CLM were randomly split into development (60%) and internal validation (40%) data sets. Kaplan-Meier method was used to estimate LTPFS and overall survival (OS) rates. Independent factors affecting LTPFS in the development data set were investigated by using multivariable Cox proportional hazard regression analysis. Risk scores were assigned to the risk factors and applied to the validation data set. Results A total of 365 patients (mean age, 60 years ± 11 [standard deviation]; 259 men) with 512 CLMs were evaluated. LTPFS and OS rates were 85% and 92% at 1 year, 73% and 41% at 5 years, 72% and 30% at 10 years, and 72% and 28% at 15 years, respectively. Independent risk factors for LTP included tumor size of 2 cm or greater (hazard ratio [HR], 3.8; 95% CI: 2.3, 6.2; < .001), subcapsular tumor location (HR, 1.9; 95% CI: 1.1, 3.1; = .02), and minimal ablative margin of 5 mm or less (HR, 11.7; 95% CI: 4.7, 29.2; < .001). A prediction model that used the risk factors had areas under the curve of 0.89, 0.92, and 0.90 at 1, 5, and 10 years, respectively, and it showed significantly better areas under the curve when compared with the model using the minimal ablative margin of 5 mm or less alone. Conclusion Radiofrequency ablation provided long-term control of colorectal liver metastases. Although minimal ablative margin of 5 mm or less was the most dominant factor, the multifactorial approach including tumor size and subcapsular location better predicted local tumor progression-free survival. © RSNA, 2020 See also the editorial by Soulen and Sofocleous in this issue.
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http://dx.doi.org/10.1148/radiol.2020200109DOI Listing
January 2021

Diagnostic performance of MRI for HCC according to contrast agent type: a systematic review and meta-analysis.

Hepatol Int 2020 Dec 4;14(6):1009-1022. Epub 2020 Nov 4.

Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 88 Olympic-ro 43-gil, Songpa-gu, Seoul, 05505, Republic of Korea.

Background/purpose: Conflicting results have been reported between the use of extracellular contrast agent (ECA) and hepatobiliary contrast agent (HBA) when magnetic resonance imaging (MRI) is used for the diagnosis of hepatocellular carcinoma (HCC). Therefore, we aimed to compare the diagnostic performance of MRI using ECA (ECA-MRI) and HBA (HBA-MRI).

Methods: Original studies reporting the diagnostic performance of contrast-enhanced MRI for the diagnosis of HCC published between January 2010 and February 2020 were identified in a Pubmed, EMBASE, and Cochrane Library database search. The pooled sensitivity and specificity of ECA-MRI and HBA-MRI were calculated using a bivariate random effects model and compared using a joint-model bivariate meta-regression. Subgroup analyses were performed to compare the diagnostic performance of ECA-MRI and HBA-MRI according to study design, underlying liver disease, lesion size, reference standard, and imaging criteria.

Results: Of the 1760 screened articles, 31 studies were included: 15 studies included 2890 lesions imaged using ECA-MRI and 19 studies included 3893 lesions imaged using HBA-MRI. The pooled sensitivity and specificity were not significantly different between ECA-MRI (sensitivity, 72% [95% confidence interval 65-79%]; specificity 92% [89-95%]) and HBA-MRI (76% [68-83%]; 92% [87-95%], p = 0.72). Subgroup analyses did not find differences in diagnostic performance between ECA-MRI and HBA-MRI according to study design (p ≥ 0.11), underlying disease (p ≥ 0.09), lesion size (≤ 2 cm, p = 0.97), reference standard (p = 0.70), or imaging criteria (p = 0.33).

Conclusion: ECA-MRI showed similar performance to HBA-MRI in the diagnosis of HCC. The contrast agent might be selected with consideration of the advantages of each agent.
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http://dx.doi.org/10.1007/s12072-020-10100-7DOI Listing
December 2020

CT in the prediction of margin-negative resection in pancreatic cancer following neoadjuvant treatment: a systematic review and meta-analysis.

Eur Radiol 2020 Oct 30. Epub 2020 Oct 30.

Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 88 Olympic-ro 43-gil, Songpa-gu, Seoul, 05505, South Korea.

Objectives: We aimed to systematically evaluate the diagnostic accuracy of CT-determined resectability following neoadjuvant treatment for predicting margin-negative resection (R0 resection) in patients with pancreatic ductal adenocarcinoma (PDAC).

Methods: Original studies with sufficient details to obtain the sensitivity and specificity of CT-determined resectability following neoadjuvant treatment, with a reference on the pathological margin status, were identified in PubMed, EMBASE, and Cochrane databases until February 24, 2020. The identified studies were divided into two groups based on the criteria of R0 resectable tumor (ordinary criterion: resectable PDAC alone; extended criterion: resectable and borderline resectable PDAC). The meta-analytic summary of the sensitivity and specificity for each criterion was estimated separately using a bivariate random-effect model. Summary results of the two criteria were compared using a joint-model bivariate meta-regression.

Results: Of 739 studies initially searched, 6 studies (6 with ordinary criterion and 5 with extended criterion) were included for analysis. The meta-analytic summary of sensitivity and specificity was 45% (95% confidence interval [CI], 19-73%; I = 88.3%) and 85% (95% CI, 65-94%; I = 60.5%) for the ordinary criterion, and 81% (95% CI, 71-87%; I = 0.0%) and 42% (95% CI, 28-57%; I = 6.2%) for the extended criterion, respectively. The diagnostic accuracy significantly differed between the two criteria (p = 0.02).

Conclusions: For determining resectability on CT, the ordinary criterion might be highly specific but insensitive for predicting R0 resection, whereas the extended criterion increased sensitivity but would decrease specificity. Further investigations using quantitative parameters may improve the identification of R0 resection.

Key Points: • CT-determined resectability of PDAC after neoadjuvant treatment using the ordinary criterion shows low sensitivity and high specificity in predicting R0 resection. • With the extended criterion, CT-determined resectability shows higher sensitivity but lower specificity than with the ordinary criterion. • CT-determined resectability with both criteria achieved suboptimal diagnostic performances, suggesting that care should be taken while selecting surgical candidates and when determining the surgical extent after neoadjuvant treatment in patients with PDAC.
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http://dx.doi.org/10.1007/s00330-020-07433-0DOI Listing
October 2020

The Liver Imaging Reporting and Data System tumor-in-vein category: a systematic review and meta-analysis.

Eur Radiol 2021 Apr 1;31(4):2497-2506. Epub 2020 Oct 1.

Department of Radiology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul, 06591, Republic of Korea.

Objectives: We aimed to systematically determine the etiology of the Liver Imaging Reporting and Data System (LI-RADS) tumor-in-vein category (LR-TIV) on contrast-enhanced CT or MRI and to determine the sources of heterogeneity between reported results.

Methods: Original studies reporting the etiology of LR-TIV were identified in MEDLINE and EMBASE up until July 7, 2020. The meta-analytic pooled percentages of HCC and non-HCC in LR-TIV were calculated. Subgroup analyses were performed according to the type of reference standard and the most common underlying liver disease. Meta-regression analysis was performed to explore study heterogeneity.

Results: Sixteen studies reported the etiology of a total of 150 LR-TIV, of which 98 (65%) were HCC and 52 (35%) were non-HCC. The meta-analytic pooled percentages of HCC and non-HCC in LR-TIV were 70.9% (95% confidence interval [CI], 55.7-82.5%; I = 59%) and 29.2% (95% CI, 17.5-44.4%; I = 59%), respectively. The meta-analytic pooled percentage of HCC was lower in studies using only pathology as a reference standard (67.1%; 95% CI, 49.3-81.1%), but higher in studies in which hepatitis C was the most common underlying liver disease (81.9%; 95% CI, 11.3-99.4%) than that in the total 16 studies. Study type (cohort study versus case-control study) was significantly associated with study heterogeneity (p = 0.04).

Conclusion: The most common etiology of LR-TIV was HCC. It might be important to understand the percentage of HCC and non-HCC in LR-TIV in consideration of the type of reference standard, geographic differences, and study design.

Key Points: • The most common etiology of Liver Imaging Reporting and Data System (LI-RADS) tumor-in-vein category (LR-TIV) was hepatocellular carcinoma (HCC). • The percentage of HCC in LR-TIV was relatively low in studies using only pathology as a reference standard, but high in studies in which hepatitis C was the most common underlying liver disease. • Study type was a factor significantly influencing study heterogeneity.
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http://dx.doi.org/10.1007/s00330-020-07282-xDOI Listing
April 2021

Acute ileal perforation caused by radiation enteritis after restoration.

Ann Coloproctol 2020 Sep 18. Epub 2020 Sep 18.

Division of Colon and Rectal Surgery, Department of Surgery, University of Ulsan College of Medicine and Asan Medical Center, Seoul, Korea.

Few radiation-induced bowel perforations have been reported to date. Furthermore perforation after ileal restoration in asymptomatic patients is rare. We report the case of a 61-year-old man who was administered preoperative chemoradiotherapy for advanced rectal cancer. The patient underwent ultra-low anterior resection with ileal diversion, followed by ileal restoration. Perforation was detected nine days after restoration, and he underwent a right hemicolectomy. Histologic evaluation indicated ileal perforation caused by acute radiation enteritis.
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http://dx.doi.org/10.3393/ac.2020.07.30DOI Listing
September 2020

Inconsistency in the use of the term "validation" in studies reporting the performance of deep learning algorithms in providing diagnosis from medical imaging.

PLoS One 2020 11;15(9):e0238908. Epub 2020 Sep 11.

Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.

Background: The development of deep learning (DL) algorithms is a three-step process-training, tuning, and testing. Studies are inconsistent in the use of the term "validation", with some using it to refer to tuning and others testing, which hinders accurate delivery of information and may inadvertently exaggerate the performance of DL algorithms. We investigated the extent of inconsistency in usage of the term "validation" in studies on the accuracy of DL algorithms in providing diagnosis from medical imaging.

Methods And Findings: We analyzed the full texts of research papers cited in two recent systematic reviews. The papers were categorized according to whether the term "validation" was used to refer to tuning alone, both tuning and testing, or testing alone. We analyzed whether paper characteristics (i.e., journal category, field of study, year of print publication, journal impact factor [JIF], and nature of test data) were associated with the usage of the terminology using multivariable logistic regression analysis with generalized estimating equations. Of 201 papers published in 125 journals, 118 (58.7%), 9 (4.5%), and 74 (36.8%) used the term to refer to tuning alone, both tuning and testing, and testing alone, respectively. A weak association was noted between higher JIF and using the term to refer to testing (i.e., testing alone or both tuning and testing) instead of tuning alone (vs. JIF <5; JIF 5 to 10: adjusted odds ratio 2.11, P = 0.042; JIF >10: adjusted odds ratio 2.41, P = 0.089). Journal category, field of study, year of print publication, and nature of test data were not significantly associated with the terminology usage.

Conclusions: Existing literature has a significant degree of inconsistency in using the term "validation" when referring to the steps in DL algorithm development. Efforts are needed to improve the accuracy and clarity in the terminology usage.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0238908PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7485764PMC
November 2020

Clinical Outcome of Arthroscopic Partial Repair of Large to Massive Posterosuperior Rotator Cuff Tears: Medialization of the Attachment Site of the Rotator Cuff Tendon.

Clin Orthop Surg 2020 Sep 29;12(3):353-363. Epub 2020 Jun 29.

Department of Orthopedic Surgery, Eulji University School of Medicine, Daejeon, Korea.

Backgroud: The goal of this study was to evaluate the clinical and radiological outcomes of arthroscopic partial repair with medialization of the attachment site of the rotator cuff tendon and to identify prognostic factors affecting rotator cuff healing in patients with irreparable large to massive posterosuperior rotator cuff tears.

Methods: Between July 2012 and March 2016, 42 patients with irreparable large to massive posterosuperior rotator cuff tears underwent an arthroscopic partial repair with medialization of the attachment site of the rotator cuff tendon. All patients had a minimum of 2-year follow-up (mean, 35.4 ± 7.3 months). Clinical evaluation was performed using the visual analog scale, the University of California, Los Angeles shoulder rating scale, Constant score, and active range of motion. Radiological evaluation was performed using magnetic resonance imaging and simple radiography.

Results: Clinical outcomes at the final follow-up improved significantly compared with the preoperative values (all < 0.001). The failure rate was 23.8% (10/42); however, clinical outcomes significantly improved regardless of cuff healing (all < 0.001). The mean acromiohumeral distance was 6.5 ± 1.7 mm (range, 3.2-9.7 mm) before surgery and 6.3 ± 1.6 mm (range, 2.8-9.5 mm) at the final follow-up. Preoperative acromiohumeral distance was associated with failure of cuff healing in the univariate analysis ( = 0.043) and multivariate analysis ( = 0.048). A receiver operating characteristic curve was used to determine the predictive cutoff value for the smallest preoperative acromiohumeral distance for successful healing, which was calculated as 5.3 mm.

Conclusions: Despite healing failure, arthroscopic partial repair with medialization can be a possible treatment option for irreparable large to massive posterosuperior rotator cuff tears because of the improvement in clinical outcome. The shorter preoperative acromiohumeral distance was the single most important factor negatively affecting cuff healing, and the likelihood of success of healing might be improved if a repair is performed when the preoperative acromiohumeral distance is < 5.3 mm.
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http://dx.doi.org/10.4055/cios19126DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7449848PMC
September 2020

Lateral lymph node and its association with distant recurrence in rectal cancer: A clue of systemic disease.

Surg Oncol 2020 Dec 19;35:174-181. Epub 2020 Aug 19.

Department of Colon and Rectal Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, 05505, South Korea. Electronic address:

We analyzed oncologic outcomes according to pre-/post-LPLN enlargement. Rectal cancer patients who underwent resection post-PCRT during 2008-2012 were enrolled. Magnetic resonance imaging pre-/post-PCRT were re-evaluated. LNs with short axis (SA) ≥7 mm pre-PCRT and ≥4 mm post-PCRT were defined as enlarged nodes. Of 798 patients enrolled, recurrence occurred in 55 (6.9%) local, 17 (2.1%) lateral, and 179 (22.4%) distal regions. Patients with LPLN SA ≥7 mm pre-PCRT showed worse local recurrence-free survival (RFS), lateral RFS, and distant RFS (p < 0.001, 0.002, and 0.005, respectively). LN shrinkage post-PCRT to SA<4 mm showed better 5-year local RFS (83.5% vs. 78.3%, p = 0.045), but distant RFS was similar irrespective of LN shrinkage to <4 mm. Among patients with pre-PCRT SA ≥7 mm, node shrinkage to SA<4 mm after PCRT presented with lower incidence of local recurrence but did not benefit in distant recurrence. Lateral node sampling did not improve local recurrence control, resulting in a 5-year local RFS of 75.4% in patients undergoing lateral node sampling and 83.2% in those not undergoing lateral node sampling (p = 0.722). Four (66.7%) patients had lateral recurrence in the same area of the enlarged nodes identified pre-PCRT. For patients assessed with pre-PCRT nodes ≥7 mm, response to PCRT did not guarantee better outcomes.
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http://dx.doi.org/10.1016/j.suronc.2020.08.013DOI Listing
December 2020

Dual-source abdominopelvic computed tomography: Comparison of image quality and radiation dose of 80 kVp and 80/150 kVp with tin filter.

PLoS One 2020 3;15(9):e0231431. Epub 2020 Sep 3.

Department of Radiology, Seoul Saint Mary's Hospital, Seoul, Korea.

Objective: To compare the radiation dose and the objective and subjective image quality of 80 kVp and 80/150 kVp with tin filter (80/Sn150 kVp) computed tomography (CT) in oncology patients.

Methods: One-hundred-and-forty-five consecutive oncology patients who underwent third-generation dual-source dual-energy CT of the abdomen for evaluation of malignant visceral, peritoneal, extraperitoneal, and bone tumor were retrospectively recruited. Two radiologists independently reviewed each observation in 80 kVp CT and 80/Sn150 kVp CT. Modified line-density profile of the tumor and contrast-to-noise ratio (CNR) were measured. Diagnostic confidence, lesion conspicuity, and subjective image quality were calculated and compared between image sets. The effective dose and size-specific dose estimate (SSDE) were calculated in the image sets.

Results: Modified line-density profile analysis revealed higher attenuation differences between the tumor and normal tissue in 80 kVp CT than in 80/Sn150 kVp CT (127 vs. 107, P = 0.05). The 80 kVp CT showed increased CNR in the liver (8.0 vs. 7.6) and the aorta (18.9 vs. 16.3) than the 80/Sn150 kVp CT. The 80 kVp CT yielded higher enhancement of organs (4.9 ± 0.2 vs. 4.7 ± 0.4, P<0.001) and lesion conspicuity (4.9 ± 0.3 vs. 4.8 ± 0.5, P = 0.035) than the 80/Sn150 kVp CT; overall image quality and confidence index were comparable. The effective dose was reduced by 45.2% with 80 kVp CT (2.3 mSv ± 0.9) compared to 80/Sn150 kVp CT (4.1 mSv ± 1.5). The SSDE was 7.4 ± 3.8 mGy on 80/Sn150 kVp CT and 4.1 ± 2.2 mGy on 80 kVp CT.

Conclusions: The 80 kVp CT reduced the radiation dose by 45.2% in oncology patients while showing comparable or superior image quality to that of 80/Sn150 kVp CT for abdominal tumor evaluation.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0231431PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7470424PMC
October 2020

MRI Assessment of Complete Response to Preoperative Chemoradiation Therapy for Rectal Cancer: 2020 Guide for Practice from the Korean Society of Abdominal Radiology.

Korean J Radiol 2020 07;21(7):812-828

Department of Radiology, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.

Objective: To provide an evidence-based guide for the MRI interpretation of complete tumor response after neoadjuvant chemoradiation therapy (CRT) for rectal cancer using visual assessment on T2-weighted imaging (T2) and diffusion-weighted imaging (DWI).

Materials And Methods: PubMed MEDLINE, EMBASE, and Cochrane Library were searched on November 28, 2019 to identify articles on the following issues: 1) sensitivity and specificity of T2 or DWI for diagnosing pathologic complete response (pCR) and the criteria for MRI diagnosis; 2) MRI alone vs. MRI combined with other test(s) in sensitivity and specificity for pCR; and 3) tests to select patients for the watch-and-wait management. Eligible articles were selected according to meticulous criteria and were synthesized.

Results: Of 1615 article candidates, 55 eligible articles (for all three issues combined) were identified. Combined T2 and DWI performed better than T2 alone, with a meta-analytic summary sensitivity of 0.62 (95% confidence interval [CI], 0.43-0.77; I² = 80.60) and summary specificity of 0.89 (95% CI, 0.80-0.94; I² = 92.61) for diagnosing pCR. The criteria for the complete response on T2 in most studies had the commonality of remarkable tumor decrease to the absence of mass-like or nodular intermediate signal, although somewhat varied, as follows: (near) normalization of the wall; regular, thin, hypointense scar in the luminal side with (near) normal-appearance or homogeneous intermediate signal in the underlying wall; and hypointense thickening of the wall. The criteria on DWI were the absence of a hyperintense signal at high b-value (≥ 800 sec/mm²) in most studies. The specific algorithm to combine T2 and DWI was obscure in half of the studies. MRI combined with endoscopy was the most utilized means to select patients for the watch-and-wait management despite a lack of strong evidence to guide and support a multi-test approach.

Conclusion: This systematic review and meta-analysis provide an evidence-based practical guide for MRI assessment of complete tumor response after CRT for rectal cancer.
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http://dx.doi.org/10.3348/kjr.2020.0483DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7289703PMC
July 2020

Association of Faecal Calprotectin Level and Combined Endoscopic and Radiological Healing in Patients With Crohn's Disease Receiving Anti-tumour Necrosis Factor Therapy.

J Crohns Colitis 2020 Sep;14(9):1231-1240

Department of Gastroenterology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.

Background And Aims: Combined endoscopic and radiological healing, or deep healing, is associated with favourable outcomes in patients with Crohn's disease; thus, a non-invasive biomarker for predicting deep healing would be invaluable. We evaluated the usefulness of faecal calprotectin for predicting deep healing in patients with Crohn's disease receiving anti-tumour necrosis factor [TNF] therapy.

Methods: We analysed the records of patients with Crohn's disease who received anti-tumour necrosis factor therapy and underwent endoscopic evaluation, radiological evaluation, and faecal calprotectin measurement within a period of 3 months between August 2017 and November 2018. Results of endoscopic and radiological studies were independently reviewed by two gastrointestinal endoscopists and a gastrointestinal radiologist, respectively. Serum C-reactive protein and albumin were also measured.

Results: Out of 268 patients analysed, 77 [28.7%] had deep healing, 36 [13.4%] had endoscopic healing only, 36 [13.4%] had radiological healing only, and 119 [44.4%] had neither. The median duration of anti-TNF treatment was 40.0 months. The deep healing group had the lowest median faecal calprotectin level [56.5 mg/kg] among the four groups [p <0.001]. The faecal calprotectin cutoff level of 81.1 mg/kg showed a sensitivity of 0.623 and a specificity of 0.817 in predicting deep healing (area under the receiver operating characteristic curve [AUROC], 0.767; 95% confidence interval, 0.702-0.832). Adding serum C-reactive protein and serum albumin to faecal calprotectin further increased the AUROC to 0.805 [95% confidence interval, 0.752-0.858].

Conclusions: Faecal calprotectin, when combined with serum C-reactive protein and albumin, showed acceptable performance in predicting deep healing in patients with Crohn's disease.
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http://dx.doi.org/10.1093/ecco-jcc/jjaa042DOI Listing
September 2020

Liver imaging reporting and data system category M: A systematic review and meta-analysis.

Liver Int 2020 06 15;40(6):1477-1487. Epub 2020 Mar 15.

Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.

Background And Aims: The Liver Imaging Reporting and Data System (LI-RADS) category M (LR-M) was introduced to preserve the high specificity of LI-RADS algorithm for diagnosing hepatocellular carcinoma (HCC). We aimed to systematically determine the probability of the LR-M for HCC and non-HCC malignancy, and to determine the sources of heterogeneity between reported results.

Methods: Original studies reporting the probability of LR-M for HCC and non-HCC malignancy on magnetic resonance imaging (MRI) were identified in MEDLINE and EMBASE. The meta-analytic pooled percentages of HCC and non-HCC in LR-M were calculated. Meta-regression analysis was performed to explore study heterogeneity. The meta-analytic frequency of each LR-M imaging feature was determined.

Results: We found 10 studies reporting the diagnostic performance of LR-M (1819 lesions in 1631 patients), and six reporting the frequency of LR-M imaging features. The pooled percentages of HCC and non-HCC malignancy for LR-M were 28.2% (95% confidence interval [CI], 23.8%-33.1%; I  = 83%) and 69.6% (95% CI, 64.6%-74.1%; I  = 83%) respectively. The study type and MRI scanner field strength were significantly associated with study heterogeneity (P ≤ .04). Of the seven imaging features, rim arterial phase hyperenhancement showed the highest frequency in both non-HCC (48.9%; 95% CI, 43.0%-54.8%) and HCC groups (9.8%; 95% CI, 6.9%-13.6%).

Conclusions: The LR-M category most commonly included non-HCC malignancy but also included 28.2% of HCC. Substantial study heterogeneity was noted, and it was significantly associated with study type and MRI scanner field strength. In addition, the frequency of LR-M imaging features was variable.
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http://dx.doi.org/10.1111/liv.14420DOI Listing
June 2020

Comparison of image quality and focal lesion detection in abdominopelvic CT: Potential dose reduction using advanced modelled iterative reconstruction.

Clin Imaging 2020 Jun 18;62:41-48. Epub 2020 Jan 18.

Department of Radiology, Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 88, Olympic-ro 43-gil, Songpa-gu, Seoul 05505, Republic of Korea.

Purpose: To evaluate radiation dose exposure, diagnostic performance, and image quality of low-dose and ultralow-dose abdominopelvic CT using the advanced modelled iterative reconstruction (ADMIRE) algorithm for focal lesion detection.

Methods: One hundred thirty-nine consecutive patients underwent contrast-enhanced abdominopelvic CT using a third-generation dual-source scanner to obtain three data sets with the following tube loads: 33.3% (ultralow-dose CT), 66.7% (low-dose CT), and 100% (standard-dose CT). The diagnostic performances of standard-dose CT, low-dose CT, and ultralow-dose CT for focal lesion detection and characterization in organs of the abdominopelvic cavity were analyzed by two readers and compared with the reference standard. Image quality was measured subjectively and objectively.

Results: Focal lesion detection showed 96.5-100% sensitivity and 97.7-100% accuracy in all representative organs on low-dose CT with acceptable image quality; it showed 87.4% sensitivity and 97.9% accuracy in the liver and 80.0% sensitivity and 88.2% accuracy in the rectal shelf on ultralow-dose CT with suboptimal image quality. Indeterminate lesions were significantly more common in the liver, pancreas, and kidneys on ultralow-dose CT than on low-dose CT. Enlarged lymph nodes showed 100% sensitivity and accuracy on ultralow-dose CT. Mean effective radiation doses of low-dose CT and ultralow-dose CT were 2.6 mSv and 1.3 mSv, respectively.

Conclusions: The diagnostic performance of low-dose CT is similar to that of standard-dose abdominopelvic CT with acceptable image quality. Ultralow-dose CT cannot safely assess focal liver, pancreas, kidneys, and rectal shelf lesions but may be useful for the evaluation of enlarged lymph nodes.
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http://dx.doi.org/10.1016/j.clinimag.2020.01.017DOI Listing
June 2020

CRISPR-Cpf1 Activation of Endogenous Gene for Osteogenic Differentiation of Umbilical-Cord-Derived Mesenchymal Stem Cells.

Mol Ther Methods Clin Dev 2020 Jun 9;17:309-316. Epub 2020 Jan 9.

School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Seoul, Korea.

The CRISPR systems provide powerful genome-editing tools for wide applications in biological and medical research fields. However, the safety issue due to off-target effects of CRISPR has been one of the major hindrances of its application to regenerative medicine. The conventional CRISPR system has the intrinsic danger of inducing unpredictable mutations at non-targeted genomic loci via erroneous double-strand DNA breaks (DSBs). In this study, we demonstrate a safety-enhanced application of a recently discovered CRISPR-Cpf1 for targeted gene activation, without DNA double-strand break, to facilitate osteogenic differentiation of human umbilical-cord-derived mesenchymal stem cells (UC-MSCs). To this end, we developed a catalytically inactive AsCpf1 fused to tripartite transcription activator domain (dAsCpf1-VPR) that can induce upregulation of targeted gene expression in mammalian cells. We observed that the CRISPR-dAsCpf1-VPR activator can be applied to enhance the osteogenic differentiation of human UC-MSCs, via increasing the expression level of endogenous gene. The results suggested that the CRISPR-Cpf1 activator provides versatile methods applicable for bone regeneration and regenerative medicine.
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http://dx.doi.org/10.1016/j.omtm.2019.12.010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6994413PMC
June 2020

Interreader Agreement of Liver Imaging Reporting and Data System on MRI: A Systematic Review and Meta-Analysis.

J Magn Reson Imaging 2020 09 27;52(3):795-804. Epub 2020 Jan 27.

Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Republic of Korea.

Background: Use of the Liver Imaging Reporting and Data System (LI-RADS) is increasing, but the reported results for interreader agreement seem quite variable.

Purpose: To systematically determine the interreader agreement of LI-RADS on magnetic resonance imaging (MRI) and to determine the sources of heterogeneity between the reported results.

Study Type: Systematic review and meta-analysis.

Subjects: Fifteen original articles with 2968 lesions.

Field Strength: 1.5T and 3.0T.

Assessment: Two reviewers independently performed the data extraction. The reviewers identified and reviewed the original articles reporting the interreader agreement of LI-RADS using MRI.

Statistical Tests: The meta-analytic pooled intraclass correlation coefficient (ICC) for lesion size and kappa value (κ) for major features (arterial-phase hyperenhancement [APHE], nonperipheral washout [WO], enhancing capsule [EC]) and LI-RADS categorization (LR) were calculated using the random-effects model. Sensitivity analysis and meta-regression analysis were performed to explore the cause of study heterogeneity.

Results: The meta-analytic pooled ICC of lesion size was 0.97 (95% confidence interval [CI], 0.94-1.00). Meta-analytic pooled κ of APHE, WO, EC, and LR were 0.72 (95% CI, 0.62-0.82), 0.69 (95% CI, 0.60-0.78), 0.66 (95% CI, 0.58-0.74), and 0.70 (95% CI, 0.56-0.85), respectively. Substantial study heterogeneity was noted in all five variables (I  ≥ 89.1%, P < 0.001). Study design, type, and clarity of blinding review were factors that significantly influenced study heterogeneity (P ≤ 0.05).

Data Conclusion: LI-RADS demonstrated overall substantial interreader agreement for major features and the category on MRI, but showed heterogeneous results between studies.

Level Of Evidence: 3 TECHNICAL EFFICACY STAGE: 2 J. Magn. Reson. Imaging 2020;52:795-804.
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http://dx.doi.org/10.1002/jmri.27065DOI Listing
September 2020

Computed tomography and magnetic resonance enterography protocols and techniques: survey of the Society of Abdominal Radiology Crohn's Disease Disease-Focused Panel.

Abdom Radiol (NY) 2020 04;45(4):1011-1017

Department of Radiology, University of California, San Francisco, USA.

Purpose: To survey Society of Abdominal Radiology Crohn's Disease (CD) Disease-Focused Panel (DFP) members to understand state-of-the-art CT/MR enterography (CTE/MRE) protocols and variability between institutions.

Methods: This study was determined by an institutional review board to be "exempt" research. The survey consisted of 70 questions about CTE/MRE patient preparation, administration of contrast materials, imaging techniques, and other protocol details. The survey was administered to DFP members using SurveyMonkey® (Surveymonkey.com). Descriptive statistical analyses were performed.

Results: Responses were received from 16 DFP institutions (3 non-USA, 2 pediatric); 15 (94%) were academic/university-based. 10 (63%) Institutions image most CD patients with MRE; 4 (25%) use CTE and MRE equally. Hypoperistaltic medication is given for MRE at 13 (81%) institutions versus only 2 (13%) institutions for CTE. Most institutions have a technologist or nurse monitor oral contrast material drinking (n = 12 for CTE, 75%; n = 11 for MRE, 69%). 2 (13%) institutions use only dual-energy capable scanners for CTE, while 9 (56%) use either a single-energy or dual-energy scanner based on availability. Axial CTE images are reconstructed at 2-3 mm thickness at 8 (50%) institutions, > 3 mm at 5 (31%), and < 2 mm at 3 (19%) institutions. 13 (81%) institutions perform MRE on either 1.5 or 3T scanners without preference. All institutions perform MRE multiphase postcontrast imaging (median = 4 phases), ranging from 20 to 600 s after contrast material injection.

Conclusion: CTE and MRE protocol knowledge from DFP institutions can help radiology practices optimize/standardize protocols, potentially improving image quality and patient outcomes, permitting objective comparisons between examinations, and facilitating research.
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http://dx.doi.org/10.1007/s00261-020-02407-8DOI Listing
April 2020

MR tumor regression grade for pathological complete response in rectal cancer post neoadjuvant chemoradiotherapy: a systematic review and meta-analysis for accuracy.

Eur Radiol 2020 Apr 17;30(4):2312-2323. Epub 2020 Jan 17.

Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul, 05505, South Korea.

Objectives: To determine the diagnostic accuracy of magnetic resonance tumor regression grade (mrTRG) for pathological complete response (pCR) and its correlation with pathological findings.

Methods: Original studies that investigated the correlation of mrTRG with pathological tumor regression grade and pathological T stage were identified in MEDLINE and EMBASE up until August 31, 2018, according to PRISMA guidelines. The search terms included colorectal cancer, chemoradiation therapy, magnetic resonance imaging, and response or regression. Meta-analytic summary sensitivity and specificity for pathologic complete response (pCR) and pathologic T1 or lower than T1 stage (≤ypT1) were calculated using a bivariate random-effects model. The sensitivity and specificity were calculated in both mrTRG 1 and mrTRG 1 or 2, respectively.

Results: Six studies with 916 patients were included. The meta-analytic summary sensitivity and specificity of mrTRG 1 for pCR were 32.3% (95% CI, 18.2-50.6%) and 93.5% (95% CI, 91.5-95.1%), while for ≤ypT1 they were 31.8% (95% CI, 16.2-53.0%) and 94.7% (95% CI, 91.9-96.5%). On the contrary, sensitivity and specificity of mrTRG 1 or 2 for pCR were 69.9% (95% CI, 60.2-78.1%) and 62.2% (95% CI, 56.2-67.8%), while those for ≤ypT1 were 71.4% (95% CI, 61.6-79.6%) and 67.7% (95% CI, 59.8-74.7%).

Conclusions: mrTRG 1 showed high specificity for pCR and ≤ypT1, but suboptimal sensitivity. mrTRG 1 or 2 showed higher sensitivity for pCR and ≤ypT1, but lower specificity. Because of the suboptimal sensitivity of mrTRG 1, it might be limited as a criterion for less aggressive treatment after neoadjuvant chemoradiotherapy.

Key Points: • Magnetic resonance tumor regression grade 1 shows high specificity for pCR and ≤ypT1, but suboptimal sensitivity. • Magnetic resonance tumor regression grade 1 or 2 shows higher sensitivity for pCR and ≤ypT1, but lower specificity than magnetic resonance tumor regression grade 1 alone.
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http://dx.doi.org/10.1007/s00330-019-06565-2DOI Listing
April 2020

Small Bowel Crohn Disease at CT and MR Enterography: Imaging Atlas and Glossary of Terms.

Radiographics 2020 Mar-Apr;40(2):354-375. Epub 2020 Jan 17.

From the Department of Radiology, Thomas Jefferson University Hospital, 132 S 10th St, Philadelphia, PA 19107 (F.F.G.); Department of Radiology, Thomas Jefferson University Hospital, 132 S 10th St, Philadelphia, PA 19107 (F.F.G.); Department of Radiology, Children's Hospital of Philadelphia and University of Pennsylvania, Philadelphia, Pa (S.A.A., K.D.); Department of Radiology (J.G.F., J.L.F.) and Division of Gastroenterology and Hepatology (D.H.B.), Mayo Clinic, Rochester, Minn.; Department of Radiology, University of Michigan Health System, Ann Arbor, Mich (M.M.A.); Department of Radiology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, Ohio (J.R.D.); Department of Radiology, Rhode Island Hospital, Providence, R.I. (D.J.G.); Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY (M.C.); Imaging Institute, Cleveland Clinic, Cleveland, Ohio (N.S.G.); Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Mass (M.S.G.); Department of Radiology, University of Florida College of Medicine, Gainesville, Fla (J.R.G.); Department of Radiology, New York University Langone Health, New York, N.Y. (C.H.); Department of Radiology, Duke University Medical Center, Durham, N.C. (T.A.J.); Department of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, South Korea (S.H.P.); Department of Radiology, Hospital Clínic of Barcelona, Barcelona, Spain (J.R.); Department of Radiology, Boston University Medical Center, Boston, Mass (J.A.S.); Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY (B.T.); Centre for Medical Imaging, University College London, London, United Kingdom (S.A.T.); and Imaging Institute, Cleveland Clinic, Cleveland, Ohio (M.E.B.).

Representatives from the Society of Abdominal Radiology Crohn's Disease-Focused Panel, the Society for Pediatric Radiology, the American Gastroenterological Association, and other international experts recently reported consensus recommendations for standardized nomenclature for the interpretation and reporting of CT enterography and MR enterography findings of small bowel Crohn disease. The consensus recommendations included CT enterography and MR enterography bowel wall findings that are associated with Crohn disease, findings that occur with penetrating Crohn disease, and changes that occur in the mesentery related to Crohn disease. Also included were recommended radiology report impression statements that summarize the findings of small bowel Crohn disease at CT enterography and MR enterography. This article, authored by the Society of Abdominal Radiology Crohn's Disease-Focused Panel, illustrates the imaging findings and recommended radiology report impression statements described in the consensus recommendations with examples of CT enterography and MR enterography images. Additional interpretation guidelines for reporting CT enterography and MR enterography examinations are also presented. The recommended standardized nomenclature can be used to generate radiology report dictations that will help guide medical and surgical management for patients with small bowel Crohn disease. RSNA, 2020See discussion on this article by Heverhagen.
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http://dx.doi.org/10.1148/rg.2020190091DOI Listing
January 2020

Comparison of submillisievert CT with standard-dose CT for urolithiasis.

Acta Radiol 2020 Aug 3;61(8):1105-1115. Epub 2019 Dec 3.

Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Republic of Korea.

Background: Patients with renal stones receive multiple computed tomography (CT) examinations. We investigated whether submillisievert (sub-mSv) CT for stone detection could reduce radiation dose at exposure levels comparable to kidney, ureter, and bladder (KUB) radiography.

Purpose: To evaluate the radiation dose exposure, diagnostic performance, and image quality of sub-mSv non-contrast CT using advanced modelled iterative reconstruction algorithm with spectral filtration for the detection of urolithiasis.

Material And Methods: A total of 145 consecutive patients underwent non-contrast CT using a third-generation dual-source scanner to obtain two datasets, i.e. 16.7% (sub-mSv CT, tube detector A) and 100% (standard-dose CT, combination of tube detector A and B) tube loads with spectral filtration. The performance of sub-mSv CT for the detection of stones was analyzed by two readers and compared with that of standard-dose CT. Image quality was measured subjectively and objectively.

Results: In total, 171 stones were detected in 79 patients. The mean effective radiation doses of sub-mSv CT was 0.3 mSv. The sensitivity and specificity values for diagnosis of stones measuring ≥3 mm was 95.1% and 100% for sub-mSv CT. The sensitivity and specificity for all stone detection was 74.9% and 97.8%, respectivey, for sub-mSv CT. The image quality was lower for sub-mSv CT than for standard-dose CT ( < 0.01).

Conclusion: Sub-mSv CT can be achieved with radiation doses close to KUB radiography. Sub-mSv CT with spectral filtration can be used to detect stones measuring ≥3 mm and be used as a follow-up imaging modality as an alternative to KUB radiography.
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http://dx.doi.org/10.1177/0284185119890088DOI Listing
August 2020

Sensitivity of Various Evaluating Modalities for Predicting a Pathologic Complete Response After Preoperative Chemoradiation Therapy for Locally Advanced Rectal Cancer.

Ann Coloproctol 2019 Oct 31;35(5):275-281. Epub 2019 Oct 31.

Division of Colon and Rectal Surgery, Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.

Purpose: We investigated the sensitivity of various evaluating modalities in predicting a pathologic complete response (pCR) after preoperative chemoradiation therapy (PCRT) for locally advanced rectal cancer (LARC).

Methods: From a population of 2,247 LARC patients who underwent PCRT followed by surgery at Asan Medical Center, Seoul, Korea from January 2007 to June 2016, we retrospectively analyzed 313 patients (14.1%) who showed a pCR after surgery. Transrectal ultrasound (TRUS), high-resolution magnetic resonance imaging (MRI), abdominopelvic computed tomography (AP-CT), and endoscopy were performed within 2 weeks prior to surgery.

Results: Of the 313 patients analyzed, 256 (81.8%) had a pCR after radical surgery and 57 (18.2%) showed total regression after local excision. Preoperative TRUS, MRI, and AP-CT were performed in 283, 305, and 139 patients, respectively. Among these 3 groups, a prediction of a pCR of the primary tumor was made in 41 (14.5%), 51 (16.7%), and 27 patients (19.4%), respectively, before surgery. A prediction of a clinical N0 stage was made in 204 patients (88.3%) using TRUS, 130 (52.2%) using MRI, and 78 (65.5%) using AP-CT. Of the 211 patients who underwent endoscopy, 87 (41.2%) had a mention of clinical CR in their records. A prediction of a pathologic CR was made for 124 patients (39.6%) through at least one diagnostic modality.

Conclusion: The various evaluation methods for predicting a pCR after PCRT show a predictive sensitivity of 0.15-0.41 for primary tumors and 0.52-0.88 for lymph nodes. Endoscopy is a relatively superior modality for predicting the pCR of the primary tumor of LARC patients.
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http://dx.doi.org/10.3393/ac.2019.01.07DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6863003PMC
October 2019

Traditional Serrated Adenomas on CT Colonography: International Multicenter Experience With This Rare Colorectal Neoplasm.

AJR Am J Roentgenol 2020 02 12;214(2):355-361. Epub 2019 Nov 12.

Department of Radiology, University of Wisconsin School of Medicine and Public Health, 600 Highland Ave, Madison, WI 53792.

Serrated polyps include hyperplastic polyps, sessile serrated polyps, and traditional serrated adenomas (TSAs). Hyperplastic polyps and sessile serrated polyps account for approximately 99% of all serrated lesions; TSAs are rare. However, both sessile serrated polyps and TSAs are now recognized as precursor lesions to carcinogenesis, representing approximately one-fourth of all sporadic colorectal cancers. We report what is, to our knowledge, the first series describing the characteristics of CTAs on CT colonography (CTC). An international, multicenter, retrospective review of CT colonography-detected TSAs diagnosed between 2008 and 2018 was conducted. Data collected included patient demographics and data from CTC, optical colonoscopy, and pathologic analysis. A total of 67 proven TSAs in 58 patients (mean age, 67 years) were identified. The majority (66%) were located in the distal colon (descending colon, sigmoid colon, and rectum), and their mean size was 19 mm (range, 3-80 mm). Small (< 10 mm) TSAs typically had a simple sessile or pedunculated morphologic appearance, whereas large (≥ 10 mm) TSAs tended to be more lobulated and irregular, pedunculated, or carpetlike. The majority (88%) showed at least some contrast medium surface coating. We report what we believe to be the first multicenter experience describing the characteristics of TSAs on CTC. Unlike sessile serrated lesions, TSAs are more often left-sided and tend to be more lobulated and irregular. However, like sessile serrated polyps, most TSAs show contrast medium surface coating. Detection of these rare lesions on CTC is important, given their malignant potential.
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http://dx.doi.org/10.2214/AJR.19.21882DOI Listing
February 2020