• 제목/요약/키워드: statistical reconstruction

검색결과 207건 처리시간 0.026초

Comparing Changes in Knee Muscle Strength after Reconstruction of the Anterior and Posterior Cruciate Ligaments

  • Hyun, SangWook;Kim, SoHee;Kim, TaeHo
    • The Journal of Korean Physical Therapy
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    • 제31권6호
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    • pp.339-345
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    • 2019
  • Purpose: The purpose of this study was to identify changes in knee muscle strength after reconstruction of the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL). Methods: Thirteen subjects (males) with anterior ligament injury and ten subjects (males) with posterior ligament injury voluntarily participated in this study. Both groups were evaluated at the pre-and post-reconstruction stages using an isokinetic dynamometer. Peak torque, total work, and the hamstrings to quadriceps (H/Q) peak torque ratio were calculated at angular velocities of 60°/sec and 180°/sec. Statistical analysis was conducted on SPSS 18.0 for Windows using t-tests to compare mean differences. Results: At an angular velocity of 60°/sec, both the ACL and PCL groups showed a significant increase in muscle strength in the flexors and extensors. Muscle strength in the extensors was significantly increased in the PCL group compared to the ACL group. At an angular velocity of 180°/sec, the ACL group showed a significant increase in muscle endurance in the flexors and extensors, and the PCL group showed a significant increase in muscle endurance in the flexors. At angular velocities of 60°/sec and 180°/sec, the H/Q peak torque ratio increased in the ACL group but decreased in the PCL group. Consequently, the H/Q peak torque ratio was significantly different for the two groups. Conclusion: The results suggest that the patients with ACL injury should focus on strengthening the knee extensors and that the patients with PCL injury need to strengthen the knee flexors.

유리피판을 이용한 설재건 후의 기능평가 (Functional Assessment after Tongue Reconstruction using Free Flap)

  • 박성호;정철훈;이종욱;장용준;노영수
    • 대한두경부종양학회지
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    • 제25권2호
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    • pp.119-122
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    • 2009
  • Objectives : Ablation of carcinoma of the tongue leads to deficits in speech and swallowing, but none to date has provided all of the qualities of mobility and sensation to simulate the complex function of the tongue. The authors evaluated postoperative swallowing and pronouncing function in patients who underwent tongue reconstruction using free flap. Material and Methods : This is a retrospective review documenting the outcome of 42 patients between January of 1991 and August of 2008. We classified patients according to the size of resection of the tongue like as 7 partial glossectomy, 25 hemiglossectomy, 2 subtotal glossectomy, and 8 total glossectomy. Swallowing function was graded into 4 point scale and pronouncing function was analyzed using picture consonant articulation test. Aspiration was evaluated with videofluoroscopic swallowing study. Results : The average points for swallowing function were 3.43 in partial glossectomy, 3.52 in hemiglossectomy, 3 in subtotal glossectomy, and 2.63 in total glossectomy. The percentage of consonants correct showed 76.5% in partial glossectomy, 72.29% in hemiglossectomy, 47.69% in subtotal glossectomy, and 29.94% in total glossectomy. Aspiration was noted in 3 patients(1 hemiglossectomy and 2 total glossectomy) and 2 total glossectomy patients were taken permanent feeding gastrostomy. Conclusion : Free flap gave us proper volume in tongue reconstruction and showed good result in preserving swallowing function. Swallowing function difference according to the size of defect showed no statistical significance, whereas articulation function was shown to decrease in accuracy as the size of defect was larger.

사지재건을 위한 서혜부 유리피부편 이식술 (The Free Vascularized Groin Flap for the Reconstruction of Extremity)

  • 한수봉;박영희;강호정
    • Archives of Reconstructive Microsurgery
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    • 제7권1호
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    • pp.1-9
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    • 1998
  • From January 1985 to February 1997, 96 patients had undergone the free vascularized groin flap on the upper and lower extremities with microsurgical technique at the department of orthopaedic surgery, Yonsei University College of Medicine. The results were as follows: 1. Average age at the time of operation was 24.9 years. and there were 71 men and 25 women and mean follow up was 62.4 months. 2. The lesion site was 82 cases on the lower extremity: foot(40), leg(20), ankle(13), and 14 cases on the upper extremity: forearm(6), elbow(3), hand(3), wrist(2). 3. The anatomical classification of the superficial circumflex iliac artery was as follows: 1) 39.8% of common origin with superficial inferior epigastric artery, 2) 30.1% of isolated origin and absent superficial inferior epigastric artery, 3) 13.3% of separate origin, 4) 16.9% of origin from the deep femoral artery. 4. There was no statistical significance on arterial anastomosis between end to end and end to side, and on venous anastomosis(end to end) between one vein and two veins. 5. The success rate was average 84.4% in 81 of 96 cases. 6. In the 15 failed cases, the additional procedures were performed: 5 cases of free vascularized scapular flap, 6 cases of full thickness skin graft, 2 cases of cross leg flap, 1 case of latissimus dorsi flap, 1 case of split thickness skin graft. In conclusion, the free vascularized groin flap can be considered as the treatment of choice for the reconstruction of the extensive soft tissue injury on the extremities, and show the higher success rate with the experienced surgeon.

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역학적 등방성을 가진 2상 다결정 미세구조의 재구성 기법 (Reconstruction of Two-phase Polycrystalline Microstructures of Mechanical Isotropy)

  • 정상엽;한동석
    • 한국방재학회 논문집
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    • 제11권2호
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    • pp.31-37
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    • 2011
  • 다상 재료는 상(phase) 분포의 차이에 따라 재료의 특성이 다르기 때문에 상 분포 상태의 특성을 이해하는 것이 중요하다. 본 연구에서는 확률 분포 함수를 사용하여 미세구조의 상 분포 상태를 나타내고, 이를 사용한 미세구조 재구성 방법을 이용해서 특정 2상 미세구조와 통계적으로 유사한 상 분포를 가진 미세구조를 생성하여 기존의 미세구조와 재구성된 미세구조의 특성을 비교하였다. 그리고 서로 다른 임의의 상 분포를 가진 미세구조들에 유한요소해석 기법을 적용하여 서로 다른 하중 방향에 대한 미세구조의 역학적 거동을 분석하였다. 이를 통해, 미세구조 재구성 방법을 사용하여, 제한된 정보만을 이용해서 통계적으로 유사한 특성을 나타내는 미세구조를 모델링 할 수 있음을 확인하였고, 확률 분포 함수와 미세구조의 역학적 거동이 방향에 따라 동일함을 통하여 재생성 된 재료의 등방성을 확인하였다.

Estimation of Noise Level and Edge Preservation for Computed Tomography Images: Comparisons in Iterative Reconstruction

  • Kim, Sihwan;Ahn, Chulkyun;Jeong, Woo Kyoung;Kim, Jong Hyo;Chun, Minsoo
    • 한국의학물리학회지:의학물리
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    • 제32권4호
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    • pp.92-98
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    • 2021
  • Purpose: This study automatically discriminates homogeneous and structure edge regions on computed tomography (CT) images, and it evaluates the noise level and edge preservation ratio (EPR) according to the different types of iterative reconstruction (IR). Methods: The dataset consisted of CT scans of 10 patients reconstructed with filtered back projection (FBP), statistical IR (iDose4), and iterative model-based reconstruction (IMR). Using the 10th and 85th percentiles of the structure coherence feature, homogeneous and structure edge regions were localized. The noise level was estimated using the averages of the standard deviations for five regions of interests (ROIs), and the EPR was calculated as the ratio of standard deviations between homogeneous and structural edge regions on subtraction CT between the FBP and IR. Results: The noise levels were 20.86±1.77 Hounsfield unit (HU), 13.50±1.14 HU, and 7.70±0.46 HU for FBP, iDose4, and IMR, respectively, which indicates that iDose4 and IMR could achieve noise reductions of approximately 35.17% and 62.97%, respectively. The EPR had values of 1.14±0.48 and 1.22±0.51 for iDose4 and IMR, respectively. Conclusions: The iDose4 and IMR algorithms can effectively reduce noise levels while maintaining the anatomical structure. This study suggested automated evaluation measurements of noise levels and EPRs, which are important aspects in CT image quality with patients' cases of FBP, iDose4, and IMR. We expect that the inclusion of other important image quality indices with a greater number of patients' cases will enable the establishment of integrated platforms for monitoring both CT image quality and radiation dose.

Functional outcome predictors following mandibular reconstruction with osteocutaneous fibula free flaps: correlating early postoperative videofluoroscopic swallow studies with long-term clinical results

  • Gonzalez, Santiago R.;Hobbs, Bradley;Vural, Emre;Moreno, Mauricio A.
    • Maxillofacial Plastic and Reconstructive Surgery
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    • 제41권
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    • pp.30.1-30.8
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    • 2019
  • Background: Advancements in the field of microvascular surgery and the widespread adoption of microvascular surgical techniques have made the use of osteocutaneous fibula free flaps the standard of care in the surgical management of segmental mandibular defects. Although the literature possesses abundant evidence to support the effectiveness of fibula free flaps as a reconstructive method, there are relatively few studies reporting on outcomes as objectively measured by videofluoroscopic swallowing studies (VFSS). The purpose of this study is to explore the potential correlation between early postoperative VFSS and the long-term swallowing outcomes in patients who underwent mandibular reconstruction with fibula free flaps. Methods: We performed a retrospective chart review of 36 patients who underwent mandibular reconstruction with osteocutaneous fibular free flaps between 2009 and 2012. Demographics, clinical variables, VFSS data, and diet information were retrieved. Penetration and aspiration findings on VFSS, long-term oral feeding ability, and the need for gastrostomy tube were statistical endpoints correlated with postoperative clinical outcomes. Results: Thirty-six patients were reviewed (15 females and 21 males) with a mean age of 54 years (7-81). Seventeen cases were treated for malignancy. The size of the bony defect ranged from 3 to 15 cm (mean = 9 cm). The cutaneous paddle, a surrogate for soft tissue defect, ranged from 10 to 125 ㎠ (mean = 52 ㎠). A gastrostomy tube was present in patients preoperatively (n = 8), and postoperatively (n = 14). Seventeen patients had neoadjuvant exposure to radiation. Postoperative VFSS showed penetration in 13 cases (36%) and aspiration in seven (19%). Overall, 29 patients (80.6%) achieved unrestricted diet, and this was statistically correlated with age (p = 0.037), radiation therapy (p = 0.002), and preoperative gastrostomy tube (p = 0.03). The presence of penetration or aspiration on VFSS was a strong predictor for long-term unrestricted oral diet (p < 0.001). Conclusion: Early postoperative VFSS is an excellent predictor for long-term swallowing outcomes in patients undergoing mandibular reconstruction with osteocutaneous fibula free flaps.

비디오 시퀀스로부터 고해상도 정지영상 복원을 위한 입력영상 선택 알고리즘 (An Improved Input Image Selection Algorithm for Super Resolution Still Image Reconstruction from Video Sequence)

  • 이시경;조효문;조상복
    • 융합신호처리학회논문지
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    • 제9권1호
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    • pp.18-23
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    • 2008
  • 본 논문에서는 SR(Super Resolution) 복원 과정에 있어 사용되는 입력 후보 영상 중 적합한 입력 영상을 자동 선택하는 알고리즘을 제안함으로써 복원된 고해상도 영상의 질을 개선하고자 한다. SR 복원과정에서 이상적인 결과 영상을 얻기 위해서는 입력되는 모든 영상이 유기적으로 잘 정합 되어야 하지만, 실제로는 그렇지 못하다. 이런 이유로 입력 후보군 영상의 정합 적합성이 얼마나 높은가가 단순히 많은 입력 영상의 수보다 고품질의 고해상도 결과 영상을 얻는데 더욱 결정적이라 할 수 있다. 입력 영상의 적합성은 통계 특성 및 정합 특성을 이용하여 평가 가능하다. 그러므로 본 논문에서는 SR 복원과정에 정합 적합성을 자동으로 평가하여 이에 따라 입력 영상을 결정하는 전처리 과정을 제안하고 구조화하였다. 또한 비디오 시퀀스의 모든 입력 영상은 SR 복원과정의 기준 영상이나 저해상도 입력 영상과 같이 사용될 수 있으므로 본 논문에서는 연속적인 비디오 시퀀스를 위한 SR 복원알고리즘을 제안한다. 적합성의 유무는 임계값(Threshold Value)에 의해 결정되며, 이 임계값은 기준 영상과의 움직임 추정에서 그 보상 값의 오류 값 중 최대치(MMCE, Maximum Motion Compensation Error)로 결정된다. 만약 저해상도 입력 영상의 보상 오류 값의 범위가 0과 MMCE사이(0 < MCE < MMCE )값이라면 그 범위 안의 입력 후보 영상은 SR 복원과정에 사용되며 범위 밖의 후보영상은 제외된다. 최적의 저해상도 기준(ORLR, Optimal Reference Low Resolution)영상은 선택된 저해상도 입력(SLRI, Selected LR Input)영상들과 각각의 저해상도 기준 입력(RLRI, Reference Low Resolution Input)영상들의 비교를 통해 결정된다. 본 논문에서는 이와 같은 과정에 의해 결정된 저해상도의 최적 기준영상과 선택영상을 'Hardie' 보간법을 사용하여 고해상도 영상을 만들어 내는 것으로 사용자의 조정이 없이도 SR 복원영상의 질적 향상을 가져올 것이라 기대된다.

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Long-term Follow-up for Type 2 Diabetes Mellitus after Gastrectomy in Non-morbidly Obese Patients with Gastric Cancer: the Legitimacy of Onco-metabolic Surgery

  • Lee, Tae-Hoon;Lee, Chang Min;Park, Sungsoo;Jung, Do Hyun;Jang, You Jin;Kim, Jong-Han;Park, Seong-Heum;Mok, Young-Jae
    • Journal of Gastric Cancer
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    • 제17권4호
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    • pp.283-294
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    • 2017
  • Purpose: This study primarily aimed to investigate the short- and long-term remission rates of type 2 diabetes (T2D) in patients who underwent surgical treatment for gastric cancer, especially patients who were non-obese, and secondarily to determine the potential factors associated with remission. Materials and Methods: We retrospectively reviewed the clinical records of patients with T2D who underwent radical gastrectomy for gastric cancer, from January 2008 to December 2012. Results: T2D improved in 39 out of 70 (55.7%) patients at the postoperative 2-year follow-up and 21 of 42 (50.0%) at the 5-year follow-up. In the 2-year data analysis, preoperative body mass index (BMI) (P=0.043), glycated hemoglobin (A1C) level (P=0.039), number of anti-diabetic medications at baseline (P=0.040), reconstruction method (statistical difference was noted between Roux-en-Y reconstruction and Billroth I; P=0.035) were significantly related to the improvement in glycemic control. Unlike the results at 2 years, the 5-year data analysis revealed that only preoperative BMI (P=0.043) and A1C level (P=0.039) were statistically significant for the improvement in glycemic control; however, the reconstruction method was not. Conclusions: All types of gastric cancer surgery can be effective in short- and long-term T2D control in non-obese patients. In addition, unless long-limb bypass is considered in gastric cancer surgery, the long-term glycemic control is not expected to be different between the reconstruction methods.

Validation of Deep-Learning Image Reconstruction for Low-Dose Chest Computed Tomography Scan: Emphasis on Image Quality and Noise

  • Joo Hee Kim;Hyun Jung Yoon;Eunju Lee;Injoong Kim;Yoon Ki Cha;So Hyeon Bak
    • Korean Journal of Radiology
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    • 제22권1호
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    • pp.131-138
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    • 2021
  • Objective: Iterative reconstruction degrades image quality. Thus, further advances in image reconstruction are necessary to overcome some limitations of this technique in low-dose computed tomography (LDCT) scan of the chest. Deep-learning image reconstruction (DLIR) is a new method used to reduce dose while maintaining image quality. The purposes of this study was to evaluate image quality and noise of LDCT scan images reconstructed with DLIR and compare with those of images reconstructed with the adaptive statistical iterative reconstruction-Veo at a level of 30% (ASiR-V 30%). Materials and Methods: This retrospective study included 58 patients who underwent LDCT scan for lung cancer screening. Datasets were reconstructed with ASiR-V 30% and DLIR at medium and high levels (DLIR-M and DLIR-H, respectively). The objective image signal and noise, which represented mean attenuation value and standard deviation in Hounsfield units for the lungs, mediastinum, liver, and background air, and subjective image contrast, image noise, and conspicuity of structures were evaluated. The differences between CT scan images subjected to ASiR-V 30%, DLIR-M, and DLIR-H were evaluated. Results: Based on the objective analysis, the image signals did not significantly differ among ASiR-V 30%, DLIR-M, and DLIR-H (p = 0.949, 0.737, 0.366, and 0.358 in the lungs, mediastinum, liver, and background air, respectively). However, the noise was significantly lower in DLIR-M and DLIR-H than in ASiR-V 30% (all p < 0.001). DLIR had higher signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) than ASiR-V 30% (p = 0.027, < 0.001, and < 0.001 in the SNR of the lungs, mediastinum, and liver, respectively; all p < 0.001 in the CNR). According to the subjective analysis, DLIR had higher image contrast and lower image noise than ASiR-V 30% (all p < 0.001). DLIR was superior to ASiR-V 30% in identifying the pulmonary arteries and veins, trachea and bronchi, lymph nodes, and pleura and pericardium (all p < 0.001). Conclusion: DLIR significantly reduced the image noise in chest LDCT scan images compared with ASiR-V 30% while maintaining superior image quality.

MODIS NDVI 시계열 자료의 통계적 특성에 기반한 NDVI 데이터 잡음 제거 방법 (A noise reduction method for MODIS NDVI time series data based on statistical properties of NDVI temporal dynamics)

  • 정명희;장석우
    • 한국산학기술학회논문지
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    • 제18권9호
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    • pp.24-33
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    • 2017
  • Multitemporal MODIS 식생 지수 (VI) 자료는 식생 활동의 프로파일을 제공하기 때문에 환경 및 기후 변화에 대한 식생 모니터링 연구에 널리 사용되고 있다. 그러나 MODIS 데이터에는 구름이나 대기 변동성 및 계측기 문제로 인해 노이즈가 발생하여 NDVI 시계열 데이터 분석과 애플리케이션 응용에 있어서 자료 정확성에 문제가 생기게 된다. 이러한 이유로, NDVI 자료를 이용한 VI 분석을 위해서는 잡음을 줄이고 고품질의 시계열 데이터 스트림을 재구성하기위한 전 처리가 필요하다. 본 연구에서는 NDVI 시계열 자료의 통계적 특성을 기반으로 불량 데이터 또는 미관측 데이터를 복원하기 위해 MODIS NDVI에 대한 데이터 재구성 방법을 제안하고 있다. 데이터 스트림 함수의 속성을 검사하면 급격한 증가나 감소와 같은 비정상적인 변화를 감지 할 수 있다. 본 연구에 제안하고 있는 방법은 정상적인 자료의 세부적 특징은 그대로 유지하면서 노이즈 자료만 수정하는 방향으로 자료를 복원할 수 있다. 제안된 기법은 시뮬레이션 데이터와 2006년부터 2012년까지의 북한지역 백두산을 대상으로 NDVI 시계열 자료를 사용하여 테스트하였고 시뮬레이션 테스트에서는 기존 wavelet이나 Gaussian 방법에 비해 본 방법이 에러율을 평균 70% 이상 줄일 수 있어 제안된 방법이 노이스가 있는 시계열 자료의 데이터 재구성에 있어 효과적임을 입증하였다.