Moon Hyung Choi

Diffusion-weighted imaging: Apparent diffusion coefficient histogram analysis for detecting pathologic complete response to chemoradiotherapy in locally advanced rectal cancer.

To investigate the usefulness of apparent diffusion coefficient (ADC) values derived from histogram analysis of the whole rectal cancer as a quantitative parameter to evaluate pathologic complete response (pCR) on preoperative magnetic resonance imaging (MRI).

Sarcopenia is negatively associated with long-term outcomes in locally advanced rectal cancer

The association of sarcopenia and visceral obesity to treatment outcome is not clear for locally advanced rectal cancer. This study evaluates the influence of skeletal muscle and visceral fat on short‐term and long‐term outcomes in locally advanced rectal cancer patients treated with neoadjuvant chemoradiation therapy followed by curative resection.

Impact of body fat and muscle distribution on severity of acute pancreatitis

BACKGROUND/OBJECTIVES Obesity is a well-established risk factor for severe acute pancreatitis (AP); however, the impact of visceral obesity or sarcopenic obesity on severity of AP has not been well studied. We compared the relationship between severity of AP and various body parameters including body weight, body mass index (BMI), subcutaneous adipose tissue (SAT), visceral adipose tissue (VAT), and visceral fat-to-muscle ratio (VMR). METHODS We analyzed the data of patients who were diagnosed with AP from 2009 to 2015. Image analysis software program (Aquarius Workstation software) was used to calculate individual VAT, SAT, and skeletal muscle areas from abdominal computed tomography scans at L3 vertebral levels. Revised Atlanta Classification was adopted to define severity of AP. Receiver operating characteristics (ROC) curves were constructed to determine the optimal threshold for predicting the severity. RESULTS Among 203 patients, 13 (6.4%) patients had severe AP and 62 (30.5%) patients had moderately severe cases. VMR demonstrated the highest area under the ROC curve [0.757, (95% confidence interval: 0.689-0.825)] in predicting moderately severe or severe AP. The optimal threshold of VMR for predicting severity was 1. The prevalence of various local complications and persistent organ failure were higher in patients with VMR over 1. CONCLUSIONS High visceral fat with low skeletal muscle volume was strongly correlated with AP severity. VMR had a stronger correlation with AP severity than body weight or BMI. This simple grading system would be useful if incorporated into future predictive scoring models.

MRI of Small Hepatocellular Carcinoma: Typical Features Are Less Frequent Below a Size Cutoff of 1.5 cm

OBJECTIVE The purposes of this study were to analyze MRI features of small hepatocellular carcinomas (HCCs) on the basis of size and to evaluate the difference in frequency of typical radiologic hallmarks of HCC (arterial enhancement and washout) according to the tumor size. MATERIALS AND METHODS Enrolled were 86 patients with 110 HCCs 3 cm or smaller who underwent surgical resection or transplantation. Two radiologists reviewed gadoxetic acid-enhanced MRI features for signal intensity of T2-weighted and T1-weighted imaging, diffusion restriction, presence of arterial enhancement, washout on portal and transitional phases, and signal intensity on the hepatobiliary phase. ROC curve analysis was performed to determine the optimal HCC cutoff size for radiologic hallmarks of HCC. Tumors were divided into two groups by cutoff size, and the frequencies of MRI features were assessed. RESULTS On ROC analysis, the optimal cutoff for radiologic hallmarks of HCC was 1.5 cm in independent and consensus reviews by two radiologists. HCCs smaller than 1.5 cm showed typical finding of HCC less frequently than HCCs 1.5 cm or larger in diameter. In subgroup analyses, HCCs with diameters between 1 and 1.5 cm showed similar MRI findings to HCCs with diameters 1 cm or less but significantly different findings compared with HCCs with diameters from 1.5 to 2 cm and 2-3 cm. CONCLUSION HCCs smaller than 1.5 cm in size less frequently showed MRI findings seen typically in larger HCCs. Therefore, small HCCs are harder to detect with certainty not only because of small size but also because of the lower frequency of typical MRI findings.

Does the Gadoxetic Acid-Enhanced Liver MRI Impact on the Treatment of Patients with Colorectal Cancer? Comparison Study with 18F-FDG PET/CT

Objectives. We evaluated the value of Gadoxetic acid-enhanced liver MRI in the preoperative staging of colorectal cancer and estimated the clinical impact of liver MRI in the management plan of liver metastasis. Methods. We identified 108 patients who underwent PET/CT and liver MRI as preoperative evaluation of colorectal cancer, between January 2011 and December 2013. We evaluated the per nodule sensitivity of PET/CT and liver MRI for liver metastasis. Management plan changes were estimated for patients with metastatic nodules newly detected on liver MRI, to assess the clinical impact. Results. We enrolled 131 metastatic nodules (mean size 1.6 cm) in 41 patients (mean age 65 years). The per nodule sensitivities of PET/CT and liver MRI were both 100% for nodules measuring 2 cm or larger but were significantly different for nodules measuring less than 2 cm (59.8% and 95.1%, resp., P = 0.0001). At least one more metastatic nodule was detected on MRI in 16 patients. Among these, 7 patients indicated changes of management plan after performing MRI. Conclusions. Gadoxetic acid-enhanced liver MRI detected more metastatic nodules compared with PET/CT, especially for small (<2 cm) nodules. The newly detected nodules induced management plan change in 43.8% (7/16) of patients.

Quality Management of Ultrasound Surveillance for Hepatocellular Carcinoma Under the Korean National Cancer Screening Program

The aim of this study was to investigate the quality of ultrasound (US) examinations for hepatocellular carcinoma surveillance under the Korean National Cancer Screening Program and to assess knowledge and experience about liver US of physicians who perform US examinations.

Preoperative sarcopenia and post‐operative accelerated muscle loss negatively impact survival after resection of pancreatic cancer

Sarcopenia and post‐operative accelerated muscle loss leading to cachexia are commonly observed in patients with pancreatic cancer. This study aimed to assess the influence of body compositions and post‐operative muscle change on survival of patients with surgically treated pancreatic cancer.

Educational Effects of Radiation Reduction During Fluoroscopic Examination of the Adult Gastrointestinal Tract

RATIONALE AND OBJECTIVES This study aimed to evaluate the effects of educating radiology residents and radiographers about radiation exposure on reduction of dose area product (DAP) and fluoroscopy time in diagnostic fluoroscopy of the gastrointestinal (GI) tract in adult patients. MATERIALS AND METHODS In April 2015, we offered 1 hour of education to radiology residents and radiographers on how to reduce radiation doses during fluoroscopic examinations. Fluoroscopic examinations of the GI tracts of adult patients performed from June 2014 to February 2016 were evaluated. A total of 2326 fluoroscopic examinations (779 and 1547 examinations before and after education, respectively) were performed, including 10 kinds of examinations. Fluoroscopy time and DAP were collected. A radiologist evaluated the number of spot images, captured images, cine video, captured video, and the use of collimation or magnification. We used the Mann-Whitney U test to assess the difference in fluoroscopy-related factors before and after education. RESULTS Median DAP decreased significantly after education, from 21.1 to 18.2 Gy∙cm2 (P < .001) in all examinations. After education DAP decreased significantly in defecography (P < .001) and fluoroscopy time decreased significantly in upper gastrointestinal series with water-soluble contrast (P < .001). Spot and cine images that increased the radiation dose were used less frequently after education than before in some kinds of examinations, especially in defecography (P < .001). More images were collimated after education in barium swallow than before (P < .001). CONCLUSIONS Educating radiologist residents and radiographers could reduce DAP in fluoroscopy examinations of the GI tract in adult patients.

Factors Related to Radiation Exposure during Lumbar Spine Intervention

Fluoroscopy guidance is useful to confirm anatomical landmark and needle location for spine intervention; however, it can lead to radiation exposure in patients, physicians, and medical staff. Physicians who used fluoroscopy should be cognizant of radiation exposure and intend to minimize radiation dose. We retrospectively reviewed three lumbar spine intervention procedures (nerve root block, medial branch block, and facet joint block) at our institution between June and December, 2014. We performed 268 procedures on 220 patients and found significant difference in radiation dose between two groups classified by performing physicians. The physician who controlled the fluoroscopy unit directly used significantly shorter fluoroscopy (6 seconds) that resulted in a smaller radiation dose (dose area product [DAP] 0.59 Gy∙cm2) than the physician supervising the radiographer controlling the fluoroscopy unit (72 seconds, DAP 5.31 Gy∙cm2, P < 0.001). The analysis indicates that the difference in fluoroscopy time depends on whether a physician or a radiographer controls the fluoroscopy unit.

Clinical Outcomes of Radiofrequency Ablation for Early Hypovascular HCC: A Multicenter Retrospective Study

Purpose To retrospectively evaluate the clinical outcomes of radiofrequency ablation (RFA) for early hypovascular hepatocellular carcinomas (HCCs) and to compare them with those of typical hypervascular HCCs. Materials and Methods This retrospective multicenter study received institutional review board approval, with a waiver of the need to obtain informed consent. A total of 56 patients (male-to-female ratio, 40:16; mean age, 61.8 years; age range, 33-87 years) with pathologically proven early HCCs that did not meet the noninvasive diagnosis criteria and who were initially treated with RFA at one of five university-affiliated hospitals between January 2009 and December 2013 comprised the study group. Thereafter, 240 patients with hypervascular HCCs initially treated with RFA in the same period in a historical cohort were selected as control patients. Overall survival (OS), progression-free survival (PFS), and cumulative incidence of local tumor progression (LTP) were estimated by using Kaplan-Meier analysis and were compared by using the Cox proportional hazard regression model. After the first analysis, propensity score analysis was performed to reduce potential bias. Results Complete ablation was achieved in all 56 patients with early hypovascular HCCs after RFA. The estimated 5-year cumulative incidence of LTP in the 56 patients with early hypovascular HCCs was significantly lower than in the 240 patients with hypervascular HCCs (5.4% for early hypovascular HCCs vs 20.8% for hypervascular HCCs; hazard ratio = 6.57 [95% confidence interval: 1.59, 27.2]; P = .009). After propensity matching, the estimated 5-year cumulative incidence of LTP in patients with early hypovascular HCCs was still significantly lower than that in patients with hypervascular HCCs (5.4% vs 23.0%; P = .025; hazard ratio = 5.71 [95% confidence interval: 1.27, 25.8]). OS was not significantly different between the groups (P = .100). One-year PFS in the 56 patients with early hypovascular HCCs, on the other hand, appeared to be favorable at 92.7%, compared with 79.4% in the 240 patients with hypervascular HCCs, but overall, PFS was not significantly different (P = .066). Conclusion RFA of early hypovascular HCCs provided similar OS and PFS compared with RFA of typical hypervascular HCCs, despite its significantly lower 5-year cumulative incidence of LTP.