• 대한의용생체공학회:의공학회지
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• 제37권2호
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• pp.90-103
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• 2016

본 연구는 유한 요소 법을 이용한 노화되어 강성/강도가 저하되는 요추 체의 얇은 피질과 해면 골의 하중 분담 비율 분석과 사용된 탄성계수들의 평가가 목적이다. 해면 골의 나은 해석을 위하여, 20년마다 압축 시험에서 얻은 탄성계수를 체적 공극 비율로 나눈 유효 탄성계수를 사용하였다. 이와 상응하는 피질 쉘도 공극 비율을 포함한 빔 이론의 수식들로부터 유효 탄성계수를 구한 후에 적용하였다. 또한 p-요소를 사용하여 수치 오차를 최소화하였다. 보고된 논문들을 참고하여 후관절 부분이 제거된 매개 변수적인 퇴행된 L3 척추 형상을 만들어 유한 요소 모델링 하였다. 일정 변위의 압축 조건을 가한 후에 여덟 조각의 부피 별로 각 뼈에서 탄성 변형률 에너지와 수직 하중의 비율을 사용하여 하중 분담 비율을 계산하였다. 결과로는 1) 20대에서 80대까지 해면 골의 하중 비율은 55%에서 49%로 감소하였다; 2) 피질 쉘은 중간 면에서 최고 비율을, 해면 골은 종판에서 최고 비율을 나타냈다; 3) 다공성 얇은 피질과 해면 골을 위한 유효 탄성계수의 사용은 적절하였다; 4) 두 방법을 이용하여 얻은 하중 분담 비율의 차이는, 전체 비율은 1% 미만 내에서 같지만 각 위치에서의 비율 값들은 약간 달랐다.

• Journal of Korean Neurosurgical Society
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• 제30권7호
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• pp.907-915
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• 2001

Objective : Percutaneous vertebroplasty is often complicated by the presence of multiple fractures or non-localizing pain in the patients with osteoporotic vertebral fractures. The purpose of this study is to estimate the value of preoperative radiologic studies in the localization of symptomatic vertebrae and to determine the factors which can influence on the clinical results. Materials and Methods : We retrospectively reviewed the clinical and radiologic data of 57 vertebrae in 30 patients underwent percutaneous vertebroplasty for osteoporotic vertebral compression fractures. Inclusion criteria was severe pain(McGill-Melzack score 3, 4 or 5) associated with the acute vertebral fractures and absence of spinal nerve root or cord compression sign. Acute symptomatic vertebral fracture was determined by the presence of signal change on MR images or increased uptake on whole body bone scan. Results : Pain improvement was obtained immediately in all patients and favorable result was sustained in 26 patients(86.7%) during the mean follow-up duration of 4.7 months(5 complete pain relief, 21 marked pain relief). Those who underwent vertebroplasty for all acute symptomatic vertebrae had significantly better clinical result than those who did not. Further vertebral collapse and eventual bursting fracture occurred in 1 vertebra which showed intradiskal leakage of bone cement and disruption of cortical endplate on postoperative CT scan. Conclusion : Preoperative MR imaging and whole body bone scan are very useful in determining the symptomatic vertebrae, especially in the patients with multiple osteoporotic vertebral fractures. To obtain favorable clinical result, the careful radiologic evaluation as well as clinical assessment is required. Control of PMMA volume seems to be the most critical point for avoiding complications.

• Korean Journal of Radiology
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• 제23권11호
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• pp.1055-1066
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• 2022

Objective: The clinical relevance of myosteatosis has not been well evaluated in patients with pancreatic ductal adenocarcinoma (PDAC), although sarcopenia has been extensively researched. Therefore, we evaluated the prognostic value of muscle quality, including myosteatosis, in patients with resectable PDAC treated surgically. Materials and Methods: We retrospectively evaluated 347 patients with resectable PDAC who underwent curative surgery (mean age ± standard deviation, 63.6 ± 9.6 years; 202 male). Automatic muscle segmentation was performed on preoperative computed tomography (CT) images using an artificial intelligence program. A single axial image of the portal phase at the inferior endplate level of the L3 vertebra was used for analysis in each patient. Sarcopenia was evaluated using the skeletal muscle index, calculated as the skeletal muscle area (SMA) divided by the height squared. The mean SMA attenuation was used to evaluate myosteatosis. Diagnostic cutoff values for sarcopenia and myosteatosis were devised using the Contal and O'Quigley methods, and patients were classified according to normal (nMT), sarcopenic (sMT), myosteatotic (mMT), or combined (cMT) muscle quality types. Multivariable Cox regression analyses were conducted to assess the effects of muscle type on the overall survival (OS) and recurrence-free survival (RFS) after surgery. Results: Eighty-four (24.2%), 73 (21.0%), 75 (21.6%), and 115 (33.1%) patients were classified as having nMT, sMT, mMT, and cMT, respectively. Compared to nMT, mMT and cMT were significantly associated with poorer OS, with hazard ratios (HRs) of 1.49 (95% confidence interval, 1.00-2.22) and 1.68 (1.16-2.43), respectively, while sMT was not (HR of 1.40 [0.94-2.10]). Only mMT was significantly associated with poorer RFS, with an HR of 1.59 (1.07-2.35), while sMT and cMT were not. Conclusion: Myosteatosis was associated with poor OS and RFS in patients with resectable PDAC who underwent curative surgery.

• Korean Journal of Radiology
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• 제21권1호
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• pp.88-100
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• 2020

Objective: We aimed to develop and validate a deep learning system for fully automated segmentation of abdominal muscle and fat areas on computed tomography (CT) images. Materials and Methods: A fully convolutional network-based segmentation system was developed using a training dataset of 883 CT scans from 467 subjects. Axial CT images obtained at the inferior endplate level of the 3rd lumbar vertebra were used for the analysis. Manually drawn segmentation maps of the skeletal muscle, visceral fat, and subcutaneous fat were created to serve as ground truth data. The performance of the fully convolutional network-based segmentation system was evaluated using the Dice similarity coefficient and cross-sectional area error, for both a separate internal validation dataset (426 CT scans from 308 subjects) and an external validation dataset (171 CT scans from 171 subjects from two outside hospitals). Results: The mean Dice similarity coefficients for muscle, subcutaneous fat, and visceral fat were high for both the internal (0.96, 0.97, and 0.97, respectively) and external (0.97, 0.97, and 0.97, respectively) validation datasets, while the mean cross-sectional area errors for muscle, subcutaneous fat, and visceral fat were low for both internal (2.1%, 3.8%, and 1.8%, respectively) and external (2.7%, 4.6%, and 2.3%, respectively) validation datasets. Conclusion: The fully convolutional network-based segmentation system exhibited high performance and accuracy in the automatic segmentation of abdominal muscle and fat on CT images.

• Investigative Magnetic Resonance Imaging
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• 제18권3호
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• pp.232-243
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• 2014

목적: 축추이하 경추 손상시 발생하는 연속적, 비연속적 연골하골 압박손상의 빈도와 원발부위 손상 패턴에 대해 알아보고자 하였다. 대상과 방법: 축추이하 경추 손상이 있는 환자 47명의 전산화 단층촬영, 자기공명영상, 의무기록을 후향적으로 검토하여 연속적, 비연속적 연골하골 압박손상의 발생유무와 수, 레벨, 손상 부위를 기록하였다. 원발부위 손상 패턴을 알아보기 위하여 손상된 원발부위의 레벨, 수, 손상 형태, 전/후방 추간판인대복합체의 손상유무, 후방인대복합체의 손상유무, 척수 손상유무를 분석하고 손상 기전을 분석하였다. 분석된 원발손상 패턴과 손상기전은 Mann-Whitney U test, Pearson's chi square test, Fisher's exact test의 통계적 기법으로 연골하 압박손상의 발생유무와 연관성을 조사하였다. 결과: 총 18명에게서 (18/47, 38.29%) 연골하 압박손상이 발생했으며 그 중 9명은 원발부위와 인접하여 연속적으로, 다른 9명은 원발부위와 떨어져 비연속적으로 발생하였다. 3번 흉추에 가장 흔하게 발생하였고 (15/47, 31.91%), 세 개의 레벨에 걸쳐있는 경우가 가장 많았다 (6/18, 33.33%). 모든 연골하 압박손상은 척추체의 전상방 부위나 상종판 주변에 발생하였으며 강한 외력의 외상과 연관되었다. 연골하 압박손상의 발생은 원발부위의 손상형태와 후방인대복합체의 손상과 통계학적으로 유의한 연관성을 보였다. 비연속적 연골하 압박손상은 연속적 연골하 압박손상에 비해 비교적 상부 경추에 원발 손상부위가 있고 후방추간판인대 복합체의 손상을 동반하는 경우가 통계학적으로 유의하게 많았다. 그외 분석한 다른 인자들은 통계학적으로 유의한 결과를 보이지 않았다. 결론: 이차성 연골하 압박손상은 흔하며 강한 외력에 의한 굴곡압박성 경추 외상과 관련 있을 것이다.