Influence of Postoperative Changes in Sarcopenia on Long-Term Survival in Non-Metastatic Colorectal Cancer Patients.

The effect of perioperative sarcopenic changes on prognosis remains unclear. We conducted a retrospective cohort study with 2333 non-metastatic colorectal cancer patients treated between January 2009 and December 2012 at the Asan Medical Center. The body composition at diagnosis was measured via abdominopelvic computed tomography (CT) using Asan-J software. Patients underwent CT scans preoperatively, as well as at 6 months-1 year and 2-3 years postoperatively. The primary outcome was the association between perioperative sarcopenic changes and survival. According to sarcopenic criteria, 1155 (49.5%), 890 (38.2%), and 893 (38.3%) patients had sarcopenia preoperatively, 6 months-1 year, and 2-3 years postoperatively, respectively. The 5-year overall survival (OS) (95.8% vs. 92.1%, hazard ratio (HR) = 2.234, p < 0.001) and 5-year recurrence-free survival (RFS) (93.2% vs. 86.2%, HR = 2.251, p < 0.001) rates were significantly lower in patients with preoperative sarcopenia. Both OS and RFS were lower in patients with persistent sarcopenia 2-3 years postoperatively than in those who recovered (OS: 96.2% vs. 90.2%, p = 0.001; RFS: 91.1% vs. 83.9%, p = 0.002). In multivariate analysis, postoperative sarcopenia was confirmed as an independent factor associated with decreased OS and RFS. Pre- and postoperative sarcopenia and changes in the condition during surveillance were associated with oncological outcomes.

Age-related changes in muscle quality and development of diagnostic cutoff points for myosteatosis in lumbar skeletal muscles measured by CT scan.

BACKGROUND & AIMS: We have sought to develop proper and useful indices for muscle quality measurements other than muscle attenuation (Hounsfield unit; HU) and to determine the diagnostic cutoff points for myosteatosis by using those indices measured at the L3 lumbar vertebrae level by CT scan. METHODS: This cross-sectional analysis included 20,664 healthy adult subjects (12,697 men and 7967 women) who underwent abdominal CT scans. Total abdominal muscle area (TAMA), on the L3 vertebra was demarcated using predetermined thresholds. Intermuscular adipose tissue area (IMAT) and skeletal muscle area (SMA) were measured. SMA was divided into normal attenuation muscle area (NAMA) and low attenuation muscle area (LAMA). Their various indices were calculated. We identified the sex-specific mean values of NAMA, LAMA, IMAT, and their indices and the cutoff points equivalent to the T-scores in the young reference group. RESULTS: The mean values of the NAMA and NAMA indices decreased with age in both sexes, LAMA, IMAT, and their indices showed an increasing tendency with age in both sexes. When using T-score < -2.0 as the cutoff for myosteatosis, the sex-specific cutoff points of NAMA, NAMA/BMI, NAMA/TAMA index, and SMA and TAMA attenuation in men and women were 103.0 and 64.5 cm2, 4.0 and 2.8, 66.4 and 65.1, 40.2 and 39.9 HU, and 34.1 and 33.5 HU, respectively. Using these cutoff points, the prevalence of myosteatosis by NAMA, NAMA/BMI, NAMA/TAMA index, or SMA or TAMA attenuation ranged from 5.9 to 8.8% in men and from 10.2 to 20.5% in women. CONCLUSIONS: The NAMA/TAMA index developed in this study was useful for assessing myosteatosis. This is the first study to report the sex-specific diagnostic cutoff points for myosteatosis of trunk muscles based on T-scores measured by CT scans in healthy population. These diagnostic cutoff points may be particularly useful in the treatment and prevention of sarcopenia and myosteatosis.

Reference Data and T-Scores of Lumbar Skeletal Muscle Area and Its Skeletal Muscle Indices Measured by CT Scan in a Healthy Korean Population.

BACKGROUND: Although computed tomography (CT) is considered the gold standard for investigating skeletal muscles, diagnostic cutoff points for sarcopenia have not been established. We therefore suggested clinically relevant diagnostic cutoff points for sarcopenia based on reference values of skeletal muscle area (SMA) measured by CT scan in a large-sized healthy Asian population. METHODS: This cross-sectional analysis included 11,845 subjects (7,314 men, 4,531 women) who underwent abdominal CT scans in South Korea. SMA including all muscles on the selected axial images of the L3 lumbar vertebrae level was demarcated using predetermined thresholds (-29 to +150 Hounsfield units). SMA indices (height-, weight-, and body mass index [BMI]-adjusted) were calculated. RESULTS: When T-score < -2.0 was used as the cutoff for defining sarcopenia, the sex-specific cutoff points of SMA, SMA/height2, SMA/weight, and SMA/BMI were 119.3 and 74.2 cm2, 39.8 and 28.4 cm2/m2, 1.65 and 1.38 cm2/kg, and 4.97 and 3.46 in men and women, respectively. In both sexes, the SMA/BMI values peaked in the 20s and decreased gradually. The SMA/BMI yielded the highest diagnostic rate of sarcopenia (4.2% in men, 8.7% in women), while SMA/height2 provided the lowest yield (2.8% in men, 1.0% in women). CONCLUSIONS: This is the first study to report the reference values of SMA and skeletal muscle indices (SMIs) measured on CT scans and to suggest cutoff points for diagnosis of sarcopenia based on T-score in Asian subjects. BMI-adjusted index (SMA/BMI) was the best index of CT-measured SMA to reflect the age-related muscle changes and to maximize the diagnostic yield for sarcopenia.

Development and Validation of a Deep Learning System for Segmentation of Abdominal Muscle and Fat on Computed Tomography.

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.

Association of Body Composition with Long-Term Survival in Non-metastatic Rectal Cancer Patients.

PURPOSE: We evaluated the association of body composition with long-term oncologic outcomes in non-metastatic rectal cancer patients. MATERIALS AND METHODS: We included 1,384 patients with stage(y)0-III rectal cancer treated at Asan Medical Center between January 2005 and December 2012. Body composition at diagnosis was measured using abdomino-pelvic computed tomography (CT). Sarcopenia, visceral obesity (VO), and sarcopenic obesity (SO) were defined using CT measured parameters such as skeletal muscle index (total abdominal muscle area, TAMA), visceral fat area (VFA), and VFA/TAMA. Inflammatory status was defined as a neutrophil-lymphocyte ratio of ≥3. Obesity was categorized by body mass index (≥ 25 kg/m2). RESULTS: Among the 1,384 patients, 944 (68.2%) had sarcopenia and 307 (22.2%) had SO. The 5-year overall survival (OS) rate was significantly lower in sarcopenic patients (no sarcopenia vs. sarcopenia; 84% vs. 78%, p=0.003) but the 5-year recurrence-free survival (RFS) rate was not different (77.3% vs. 77.9% p=0.957). Patients with SO showed lower 5-year OS (79.1% vs. 75.5% p=0.02) but no difference in 5-year RFS (p=0.957). Sarcopenia, SO, VO, and obesity were not associated with RFS. However, obesity, SO, age, sex, inflammatory status, and tumor stage were confirmed as independent factors associated with OS on multivariate analysis. In subgroup analysis, association of SO with OS was more prominent in patients with (y)p stage 0-2 and no inflammatory status. CONCLUSION: The presence of SO and a low body mass index at diagnosis are negatively associated with OS in non-metastatic rectal cancer patients.

Impact of remnant stomach volume and anastomosis on nutrition and body composition in gastric cancer patients.

BACKGROUND: In gastrectomy for gastric cancer, oncologic safety including secure resection margin is considered important while less attention is given to maximizing remnant stomach volume (RSV). Nutrition and body composition are important postoperative factors for patient well-being. In this prospective observational study, we investigated the effects of RSV and anastomosing method on nutrition, anemia, and body composition change. METHODS: We enrolled 247 patients who underwent curative laparoscopic gastrectomy (Billroth-1: 111, Billroth-2: 31, Roux-en-Y: 38, total gastrectomy: 67) for stage 1 gastric cancer between 2015 and 2016. Their clinicodemographic characteristics and laboratory data were collected. RSV, area of abdominal muscle, and subcutaneous/visceral fat were measured using CT data. RESULTS: Patients with larger RSV and those who underwent Billroth-1 exhibited smaller reduction in hemoglobin and nutritional parameters during the first three postoperative months, and showed better recovery in the aforementioned variables as well in the first postoperative year. Visceral fat was the most affected factor by gastrectomy, and abdominal muscle and subcutaneous/visceral fat were better preserved in patients with larger RSV. The proportion of sarcopenic patients was also the smallest in the Billroth-1 group and larger RSV group. Patients who underwent total gastrectomy showed the highest degree of deterioration in all parameters. CONCLUSIONS: Estimating RSV and body composition by using CT offers valuable clinical information. The Billroth-1 procedure and larger RSV were associated with better postoperative nutritional variables and reduced prevalence of sarcopenia among gastric cancer patients after gastrectomy. When performing gastrectomy in stage 1 gastric cancer patients, RSV should be considered.

Recent Issues on Body Composition Imaging for Sarcopenia Evaluation.

Recently, sarcopenia has garnered renewed interest. Sarcopenia is a disease characterized by decreased skeletal muscle mass and strength/function, which can impair the quality of life and increase physical disability, adverse metabolic effects, and mortality. Imaging tools for evaluating and diagnosing sarcopenia have developed rapidly. Radiologists should be aware of sarcopenia and its clinical implications. We review current knowledge about sarcopenia, its pathophysiological impact, and advantages and disadvantages of methods for evaluation of sarcopenia focusing on body composition imaging modalities such as whole-body dual-energy X-ray absorptiometry, CT, and MRI. Controversial issues are discussed, including the lack of consensus and standardization of the disease definition, imaging modality, measurement methods, and diagnostic cutoff points.