검색
검색 팝업 닫기

Ex) Article Title, Author, Keywords

Articles

Split Viewer

Original Article

Ann Liver Transplant 2022; 2(1): 28-33

Published online May 31, 2022 https://doi.org/10.52604/alt.22.0014

Copyright © The Korean Liver Transplantation Society.

Comparison of skeletal muscle index and body surface area-based formulae for estimation of standard liver volume

Amro H. Ageel1,4 , Jeong-Ik Park2 , Yong-Kyu Chung3 , Dong-Hwan Jung4 , Shin Hwang4

1Department of Surgery, King Abdulaziz Medical City, Jeddah, Saudi Arabia
2Department of Surgery, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, Korea
3Department of Surgery, Haeundae Paik Hospital, Inje University College of Medicine, Busan, Korea
4Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea

Correspondence to:Jeong-Ik Park
Department of Surgery, Ulsan University Hospital, 877 Bangeojinsunhwando-ro, Dong-gu, Ulsan 44033, Korea
E-mail: jipark@uuh.ulsan.kr
https://orcid.org/0000-0002-1986-9246

Received: May 1, 2022; Revised: May 12, 2022; Accepted: May 16, 2022

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/bync/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Background: Formula-derived standard liver volume (SLV) has been clinically used for living donor liver transplantation and hepatic resection. The majority of currently available SLV formulae are based on the body surface area (BSA). However, they often show a wide range of error. Skeletal muscle index measured at the third lumbar vertebra level (L3SMI) appears to reflect the lean body mass. The objective of this study was to compare the accuracy of L3SMI-based formula and BSA-based formula for calculating SLV.
Methods: The study cohort included 100 living liver donors who underwent surgery between January 2020 and December 2020. Computed tomography images were used for liver volumetry and skeletal muscle area measurement.
Results: The study cohort included 62 male and 38 female donors. Their age, BSA, L3SMI, and body mass index were 35.6±6.9 years, 1.79±0.19 m2, 51.9±9.6 cm2/m2, and 23.3±3.1 kg/m2, respectively. The L3SMI-based SLV formula was as follows: SLV (mL)=19.7×L3SMI (cm2/m2) +428.4 (R2=0.375, p<0.001). The BSA-based SLV formula was as follows: SLV (mL)=1,021.7×BSA (m2) —372.9 (R2=0.415, p<0.001). The mean difference from the actual total liver volume (TLV) was —2.7%±17.4% and 2.6%±16.5% for the L3SMI- and BSA-based formulae, respectively. A formula for the arithmetic mean of L3SMI- and BSA-based formulae was as follows: SLV (mL)=510.9×BSA (m2) +9.9×L3SMI (cm2/m2) +27.8”, with a mean difference of —2.6%±15.9% from the actual TLV.
Conclusion: The results of this study suggest that the reliability of SLV calculation with the L3SMI-based formula was not superior to that of SLV calculation with the BSA-based formula. The formula of SLV calculation using both BSA and L3SMI seems to deserve further validation studies.

Keywords: Standard liver volume, Body surface area, Skeletal muscle index, Body mass index, Liver transplantation

Body surface area (BSA)-dependent formulae for calculation of the standard liver volume (SLV) have been clinically used for relative graft size assessment for living donor liver transplantation (LDLT) [1,2]. These formulae are influenced by factors affecting BSA, such as sex, obesity, muscle mass, aging changes, and other factors. To enhance the reliability of SLV formulae, various innovative methods using anthropometric data have been attempted. One of them is the development of a SLV formula using the skeletal muscle index (SMI) measured at the third lumbar vertebra level (L3SMI) [3]. L3SMI is reported to be a surrogate marker of sarcopenia [4-8]. L3SMI also appears to more reliably reflect the lean body mass than BSA. Our previous study revealed that SLV calculation with the L3SMI-based formula was not superior to the conventional BSA-based SLV formulae [3]. Therefore, this study aimed to validate the reliability of a L3SMI-formula for calculating the SLV using a newly established living liver donor cohort.

Study Design and Patient Selection

This was a retrospective observational study. After reviewing our institutional database for LDLT, 100 living donors who underwent either right or left hepatectomy from January 2020 to December 2020 were randomly selected for this study. The institutional review board of Asan Medical Center approved the study protocol, and it waived the requirement for obtaining informed consent due to the retrospective nature of this study. This study was performed in accordance with the ethical guidelines of the World Medical Association Declaration of Helsinki 2013.

Measurement of Total Liver Volume and L3SMI

Total liver volume (TLV) was measured by computed tomography (CT) volumetry using 5-mm thick dynamic CT images. CT images were stored in a Picture Archiving and Communication System (PACS) (Petavision3; Asan Medical Center, Seoul, Korea), enabling image processing and various measurements, including liver volumetry and area measurement. The skeletal muscle area (cm2) at the third lumbar vertebra level was measured by a PACS (Petavision3; Asan Medical Center). L3SMI (cm2/m2) was calculated as the skeletal muscle area (cm2) at the third lumbar vertebra level/height (m)2.

The BSA was calculated with the Mosteller formula, which is simplified as follows: [body weight (kg)×height (cm)/3,600]0.5 [9]. Body mass index (BMI) was calculated with the following formula: body weight (kg)/height (m)2.

Statistics

Continuous numeric variables are expressed as mean with standard deviation and 95% confidence interval (95% CI), or median with range. Continuous variables were compared with the Student’s t-test. Simple linear regression analysis was performed to obtain the regression equation, correlation coefficient (r), and coefficient of determination (R2). Spearman correlation coefficient (ρ [rho]) was used for correlation analysis. A p-value <0.05 was considered to indicate a statistically significant difference. Statistical analyses were performed using SPSS version 22 (IBM Corp., Armonk, NY, USA) and MedCalc version 20.010 (MedCalc, Ostend, Belgium).

Demographic and anthropometric profiles of 100 living donors are summarized in Table 1. There were 62 male (62.0%) and 38 female (38.0%) donors, and their mean age was 35.6±6.9 years.

Table 1 . Demographic and anthropometric profiles of 100 living donors

DemographicMean±SDMedian (range)
Age (yr)35.6±6.936 (18–59)
Height (cm)170.4±9.2170 (152–191)
Body weight (kg)67.8±12.068 (42–96)
Body surface area (m2)1.79±0.191.79 (1.35–2.22)
Body mass index (kg/m2)23.3±3.123 (17–32)
Total liver volume (mL)1,452.4±308.11,428 (842–2,416)
Standardized total liver volume (mL/m2)810.7±134.8801 (516.3–1,260.4)
Skeletal muscle area at the L3 level (cm2)152.2±36.5154 (85.3–223.1)
L3 skeletal muscle index (cm2/m2)51.9±9.651.2 (35.9–75.3)

SD, standard deviation.



The median values of BSA, L3SMI, and TLV were 1.79 m2, 51.2 cm2/m2, and 1,428 mL, respectively. The median value of TLV per BSA (standardized TLV) was 801 mL/m2.

The correlation between TLV and L3SMI is depicted in Fig. 1. The correlation analysis showed that the correlation coefficient r was 0.612 (95% CI=0.473–0.722; p<0.001) and the Spearman correlation coefficient ρ was 0.641 (p<0.001). The regression equation for SLV was as follows: SLV (mL)=19.7×L3SMI (cm2/m2) +428.4 (R2=0.375, p<0.001).

Figure 1.A scatter plot of the standard liver volume formula using the skeletal muscle index at the third lumbar spine (L3SMI).

The correlation between TLV and BSA is depicted in Fig. 2. The correlation analysis showed that the correlation coefficient r was 0.644 (95% CI=0.513–0.746; p<0.001) and the Spearman correlation coefficient ρ was 0.657 (p<0.001). The regression equation for SLV was as follows: SLV (mL)=1,021.7×BSA (m2) —372.9 (R2=0.415, p<0.001).

Figure 2.A scatter plot of the standard liver volume formula using the body surface area.

The difference between the actual TLV and formula-derived TLV was analyzed. The mean difference was —2.7%±17.4% (95% CI=—6.2–0.74) for the L3SMI-based formula and 2.6%±16.5% (95% CI=—5.6–0.69) for the SLV-based formula (Fig. 3). These differences did not show a significant difference (p=0.955).

Figure 3.Comparison of volume difference percentages between the skeletal muscle index at the third lumbar spine (L3SMI)-, body surface area (BSA)-, and their combination-based standard liver volume (SLV) to the actual total liver volume (TLV).

Considering that the L3SMI- and SLV-based formulae resulted in similar values of SLV, the following formula for their arithmetic mean was obtained: SLV (mL)=510.9×BSA (m2) +9.9×L3SMI (cm2/m2) +27.8. The mean difference from the individual TLV was —2.6%±15.9% (95% CI=—5.8–0.51) (Fig. 3), which was also comparable to that for the SLV-based formula (p=0.977) and that for the L3SMI-based formula (p=0.975).

The correlation between L3SMI and BMI is depicted in Fig. 4. The correlation analysis showed that the correlation coefficient r was 0.546 (95% CI=0.392–0.671; p<0.001) and the Spearman correlation coefficient ρ was 0.589 (p<0.001). The regression equation for SLV was as follows: BMI (kg/m2)=0.174×L3SMI (cm2/m2) +14.2 (R2=0.298, p<0.001).

Figure 4.Scatter plots for correlation between the body mass index and skeletal muscle index at the third lumbar spine (L3SMI).

Moore than 16 formulae for SLV calculation have been proposed following its first introduction in 1995 [1]. We presented our first SLV formula in 1997 [10] and the second formula in 2015 [11]. In the field of LDLT, the concept of SLV was adopted to estimate the native liver volume in patients with advanced liver cirrhosis. We previously reported that comparisons between the pre-existing formula-based SLVs and actual individual TLVs showed volume errors of more than 10%, regardless of the SLV formula type, primarily due to wide inter-individual variability of TLVs [2,11-14]. Such large errors in SLV estimation based on the BSA-based formulae are natural because BSA is greatly influenced by obesity, BMI, sex, aging changes, and other factors.

To improve the accuracy of SLV prediction, we testified the L3SMI-based formula for SLV calculation in our previous study [3]. SLV calculation with the L3SMI-based formula was not superior to that with the conventional BSA-based formulae. In contrast, there is a possibility that L3SMI may more reliably reflect the lean body mass than BSA. Thus, in the present study, we aimed to validate the reliability of a L3SMI-formula for calculating the SLV using a newly established living liver donor cohort. Unlike the results of our previous study, the present study revealed that SLV estimation using the L3SMI-based formula was statistically comparable to that using the BSA-based formula. Considering that the L3SMI- and BSA-based formulae resulted in similar values of SLV, a formula for the arithmetic mean of L3SMI- and SLV-based formulae was derived, which showed a mean difference of —2.6%±15.9% from the individual TLV, which was also comparable to that for the SLV-based formula (p=0.977) and that for the L3SMI-based formula (p=0.975). Considering that the L3SMI- and SLV-based formulae resulted in similar values of SLV, a new formula for their arithmetic mean was derived as follows: SLV (mL)=510.9×BSA (m2) +9.9×L3SMI (cm2/m2) +27.8. The mean difference from the individual TLV was —2.6%±15.9%, which was also comparable to that for the SLV-based formula (2.6%±16.5%) and that for the L3SMI-based formula (—2.7%±17.4%). This new concept of SLV calculation using both BSA and L3SMI seems to deserve further validation studies.

L3SMI has been frequently studied as a surrogate marker of sarcopenia. Sarcopenia is defined as low L3SMI (lower than 41 cm2/m2 for women and lower than 53 cm2/m2 for men in Western countries) [15]. L3SMI has been found to be clinically predictive and associated with clinical endpoints, such as survival and length of hospitalization in various patient populations including post-liver transplantation and in various cancer types [4-8,16-18]. In contrast, there is a significant difference in body dimensions between healthy individuals in the Western and Eastern countries, with the latter having less muscle mass. The reference values of L3SMI for the definition of sarcopenia in the Korean population have not yet been proposed [19]. According to the Western country criteria for sarcopenia, the majority of our living donors were classified as sarcopenic.

Aging processes are inevitably accompanied by structural and functional changes in vital organs. Skeletal muscle, which accounts for 40% of the total body weight, deteriorates quantitatively and qualitatively with aging. Sarcopenia is a condition characterized by significant loss of muscle mass and strength. It is related to subsequent frailty and instability in the elderly population. Because muscle tissues have multiple functions, sarcopenia is closely related to various adverse health outcomes. Different prevalence and clinical implications of sarcopenia are highlighted by each definition. Discordances among these indices have emerged as an issue in defining sarcopenia. A unifying definition for sarcopenia has not yet been attained [20].

In the field of LDLT, sarcopenia can be a confounding variable for calculation of SLV. An international study investigated whether liver transplant candidates with sarcopenia are at an increased risk of receiving an inappropriate SLV estimation by the standard body weight (BW)-derived SLV formula [21]. Non-BW-SLV estimation formulas were tested in 262 LDLT donors and compared to the standard BW-SLV formula. The anthropometric parameters used were the thoracic width (TW-SLV) and thoraco-abdominal circumference (TAC-SLV). Subsequently, sarcopenic and non-sarcopenic LDLT candidates were compared in terms of estimated BW-SLV and non-BW-SLV. In donors, TW-SLV showed comparable concordance with CT scan-measured TLV as BW-SLV. The performance of TAC-SLV was low. In recipients, the prevalence of pretransplant sarcopenia was 30.4%. Sarcopenic patients were attributed a significantly lower BW-SLV than non-sarcopenic patients, despite comparable TW-SLV, age, body height, and gender prevalence. As a result, sarcopenic patients received a graft with a statistically lower weight at organ procurement and more frequently developed a small-for-size syndrome. The authors suggested that, in sarcopenic patients, BW-SLV formulas are affected by high risk of SLV underestimation, thus exposing them to increased risk of posttransplant small-for-size syndrome [21].

This study has a limitation worth noting. This was a retrospective single-center study with a relatively small number of samples. Further validation studies with a high number of healthy individuals are necessary to obtain more reliable results.

In conclusion, the results of this study suggest that the reliability of SLV calculation with the L3SMI-based formula was not superior to that of SLV calculation with the BSA-based formula. The formula of SLV calculation using both BSA and L3SMI seems to deserve further validation studies.

Conceptualization: AHA, JIP, SH. Data curation: All. Methodology: AHA, YKC, SH. Visualization: AHA, JIP, SH. Writing - original draft: All. Writing - review & editing: All.

  1. Urata K, Kawasaki S, Matsunami H, Hashikura Y, Ikegami T, Ishizone S, et al. Calculation of child and adult standard liver volume for liver transplantation. Hepatology 1995;21:1317-1321.
    Pubmed CrossRef
  2. Pomposelli JJ, Tongyoo A, Wald C, Pomfret EA. Variability of standard liver volume estimation versus software-assisted total liver volume measurement. Liver Transpl 2012;18:1083-1092.
    Pubmed CrossRef
  3. Yang G, Hwang S, Song GW, Jung DH. Comparison of skeletal muscle index-based formula and body surface area-based formula for calculating standard liver volume. Ann Hepatobiliary Pancreat Surg 2021;25:192-197.
    Pubmed KoreaMed CrossRef
  4. Fearon K, Strasser F, Anker SD, Bosaeus I, Bruera E, Fainsinger RL, et al. Definition and classification of cancer cachexia: an international consensus. Lancet Oncol 2011;12:489-495.
    CrossRef
  5. Montano-Loza AJ, Meza-Junco J, Baracos VE, Prado CM, Ma M, Meeberg G, et al. Severe muscle depletion predicts postoperative length of stay but is not associated with survival after liver transplantation. Liver Transpl 2014;20:640-648.
    Pubmed CrossRef
  6. Shen W, Punyanitya M, Wang Z, Gallagher D, St-Onge MP, Albu J, et al. Total body skeletal muscle and adipose tissue volumes: estimation from a single abdominal cross-sectional image. J Appl Physiol (1985) 2004;97:2333-2338.
    Pubmed CrossRef
  7. Golse N, Bucur PO, Ciacio O, Pittau G, Sa Cunha A, Adam R, et al. A new definition of sarcopenia in patients with cirrhosis undergoing liver transplantation. Liver Transpl 2017;23:143-154.
    Pubmed CrossRef
  8. Prado CM, Lieffers JR, McCargar LJ, Reiman T, Sawyer MB, Martin L, et al. Prevalence and clinical implications of sarcopenic obesity in patients with solid tumours of the respiratory and gastrointestinal tracts: a population-based study. Lancet Oncol 2008;9:629-635.
    CrossRef
  9. Mosteller RD. Simplified calculation of body-surface area. N Engl J Med 1987;317:1098.
    Pubmed CrossRef
  10. Hwang S, Lee SG, Lee YJ, Park KM, Jeon HB, Kim PN, et al. Calculation of standard liver volume of Korean adults. Korean J Hepatobiliary Pancreat Surg 1997;1:59-65.
  11. Hwang S, Ha TY, Song GW, Jung DH, Ahn CS, Moon DB, et al. Quantified risk assessment for major hepatectomy via the indocyanine green clearance rate and liver volumetry combined with standard liver volume. J Gastrointest Surg 2015;19:1305-1314.
    Pubmed CrossRef
  12. Hashimoto T, Sugawara Y, Tamura S, Hasegawa K, Kishi Y, Kokudo N, et al. Estimation of standard liver volume in Japanese living liver donors. J Gastroenterol Hepatol 2006;21:1710-1713.
    Pubmed CrossRef
  13. Yuan D, Lu T, Wei YG, Li B, Yan LN, Zeng Y, et al. Estimation of standard liver volume for liver transplantation in the Chinese population. Transplant Proc 2008;40:3536-3540.
    Pubmed CrossRef
  14. Poovathumkadavil A, Leung KF, Al Ghamdi HM, Othman Iel H, Meshikhes AW. Standard formula for liver volume in Middle Eastern Arabic adults. Transplant Proc 2010;42:3600-3605.
    Pubmed CrossRef
  15. Martin L, Birdsell L, Macdonald N, Reiman T, Clandinin MT, McCargar LJ, et al. Cancer cachexia in the age of obesity: skeletal muscle depletion is a powerful prognostic factor, independent of body mass index. J Clin Oncol 2013;31:1539-1547.
    Pubmed CrossRef
  16. Kim EY, Kim YS, Park I, Ahn HK, Cho EK, Jeong YM. Prognostic significance of CT-determined sarcopenia in patients with small-cell lung cancer. J Thorac Oncol 2015;10:1795-1799.
    Pubmed CrossRef
  17. Kim EY, Lee HY, Kim YS, Park I, Ahn HK, Cho EK, et al. Prognostic significance of cachexia score assessed by CT in male patients with small cell lung cancer. Eur J Cancer Care (Engl) 2018;27:e12695.
    Pubmed CrossRef
  18. Zheng ZF, Lu J, Zheng CH, Li P, Xie JW, Wang JB, et al. A novel prognostic scoring system based on preoperative sarcopenia predicts the long-term outcome for patients after R0 resection for gastric cancer: experiences of a high-volume center. Ann Surg Oncol 2017;24:1795-1803.
    Pubmed CrossRef
  19. Kim KM, Jang HC, Lim S. Differences among skeletal muscle mass indices derived from height-, weight-, and body mass index-adjusted models in assessing sarcopenia. Korean J Intern Med 2016;31:643-650.
    Pubmed KoreaMed CrossRef
  20. Merrill Z, Perera S, Chambers A, Cham R. Age and body mass index associations with body segment parameters. J Biomech 2019;88:38-47.
    Pubmed CrossRef
  21. Pravisani R, Hidaka M, Baccarani U, Ono S, Isola M, Kugiyama T, et al. Effect of pre-transplant sarcopenia on the estimation of standard liver volume in living-donor liver transplant candidates: risk factor for post-transplant small-for-size syndrome? A retrospective study. Transpl Int 2020;33:1282-1290.
    Pubmed CrossRef

Article

Original Article

Ann Liver Transplant 2022; 2(1): 28-33

Published online May 31, 2022 https://doi.org/10.52604/alt.22.0014

Copyright © The Korean Liver Transplantation Society.

Comparison of skeletal muscle index and body surface area-based formulae for estimation of standard liver volume

Amro H. Ageel1,4 , Jeong-Ik Park2 , Yong-Kyu Chung3 , Dong-Hwan Jung4 , Shin Hwang4

1Department of Surgery, King Abdulaziz Medical City, Jeddah, Saudi Arabia
2Department of Surgery, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, Korea
3Department of Surgery, Haeundae Paik Hospital, Inje University College of Medicine, Busan, Korea
4Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea

Correspondence to:Jeong-Ik Park
Department of Surgery, Ulsan University Hospital, 877 Bangeojinsunhwando-ro, Dong-gu, Ulsan 44033, Korea
E-mail: jipark@uuh.ulsan.kr
https://orcid.org/0000-0002-1986-9246

Received: May 1, 2022; Revised: May 12, 2022; Accepted: May 16, 2022

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/bync/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background: Formula-derived standard liver volume (SLV) has been clinically used for living donor liver transplantation and hepatic resection. The majority of currently available SLV formulae are based on the body surface area (BSA). However, they often show a wide range of error. Skeletal muscle index measured at the third lumbar vertebra level (L3SMI) appears to reflect the lean body mass. The objective of this study was to compare the accuracy of L3SMI-based formula and BSA-based formula for calculating SLV.
Methods: The study cohort included 100 living liver donors who underwent surgery between January 2020 and December 2020. Computed tomography images were used for liver volumetry and skeletal muscle area measurement.
Results: The study cohort included 62 male and 38 female donors. Their age, BSA, L3SMI, and body mass index were 35.6±6.9 years, 1.79±0.19 m2, 51.9±9.6 cm2/m2, and 23.3±3.1 kg/m2, respectively. The L3SMI-based SLV formula was as follows: SLV (mL)=19.7×L3SMI (cm2/m2) +428.4 (R2=0.375, p<0.001). The BSA-based SLV formula was as follows: SLV (mL)=1,021.7×BSA (m2) —372.9 (R2=0.415, p<0.001). The mean difference from the actual total liver volume (TLV) was —2.7%±17.4% and 2.6%±16.5% for the L3SMI- and BSA-based formulae, respectively. A formula for the arithmetic mean of L3SMI- and BSA-based formulae was as follows: SLV (mL)=510.9×BSA (m2) +9.9×L3SMI (cm2/m2) +27.8”, with a mean difference of —2.6%±15.9% from the actual TLV.
Conclusion: The results of this study suggest that the reliability of SLV calculation with the L3SMI-based formula was not superior to that of SLV calculation with the BSA-based formula. The formula of SLV calculation using both BSA and L3SMI seems to deserve further validation studies.

Keywords: Standard liver volume, Body surface area, Skeletal muscle index, Body mass index, Liver transplantation

INTRODUCTION

Body surface area (BSA)-dependent formulae for calculation of the standard liver volume (SLV) have been clinically used for relative graft size assessment for living donor liver transplantation (LDLT) [1,2]. These formulae are influenced by factors affecting BSA, such as sex, obesity, muscle mass, aging changes, and other factors. To enhance the reliability of SLV formulae, various innovative methods using anthropometric data have been attempted. One of them is the development of a SLV formula using the skeletal muscle index (SMI) measured at the third lumbar vertebra level (L3SMI) [3]. L3SMI is reported to be a surrogate marker of sarcopenia [4-8]. L3SMI also appears to more reliably reflect the lean body mass than BSA. Our previous study revealed that SLV calculation with the L3SMI-based formula was not superior to the conventional BSA-based SLV formulae [3]. Therefore, this study aimed to validate the reliability of a L3SMI-formula for calculating the SLV using a newly established living liver donor cohort.

MATERIALS AND METHODS

Study Design and Patient Selection

This was a retrospective observational study. After reviewing our institutional database for LDLT, 100 living donors who underwent either right or left hepatectomy from January 2020 to December 2020 were randomly selected for this study. The institutional review board of Asan Medical Center approved the study protocol, and it waived the requirement for obtaining informed consent due to the retrospective nature of this study. This study was performed in accordance with the ethical guidelines of the World Medical Association Declaration of Helsinki 2013.

Measurement of Total Liver Volume and L3SMI

Total liver volume (TLV) was measured by computed tomography (CT) volumetry using 5-mm thick dynamic CT images. CT images were stored in a Picture Archiving and Communication System (PACS) (Petavision3; Asan Medical Center, Seoul, Korea), enabling image processing and various measurements, including liver volumetry and area measurement. The skeletal muscle area (cm2) at the third lumbar vertebra level was measured by a PACS (Petavision3; Asan Medical Center). L3SMI (cm2/m2) was calculated as the skeletal muscle area (cm2) at the third lumbar vertebra level/height (m)2.

The BSA was calculated with the Mosteller formula, which is simplified as follows: [body weight (kg)×height (cm)/3,600]0.5 [9]. Body mass index (BMI) was calculated with the following formula: body weight (kg)/height (m)2.

Statistics

Continuous numeric variables are expressed as mean with standard deviation and 95% confidence interval (95% CI), or median with range. Continuous variables were compared with the Student’s t-test. Simple linear regression analysis was performed to obtain the regression equation, correlation coefficient (r), and coefficient of determination (R2). Spearman correlation coefficient (ρ [rho]) was used for correlation analysis. A p-value <0.05 was considered to indicate a statistically significant difference. Statistical analyses were performed using SPSS version 22 (IBM Corp., Armonk, NY, USA) and MedCalc version 20.010 (MedCalc, Ostend, Belgium).

RESULTS

Demographic and anthropometric profiles of 100 living donors are summarized in Table 1. There were 62 male (62.0%) and 38 female (38.0%) donors, and their mean age was 35.6±6.9 years.

Table 1 .. Demographic and anthropometric profiles of 100 living donors.

DemographicMean±SDMedian (range)
Age (yr)35.6±6.936 (18–59)
Height (cm)170.4±9.2170 (152–191)
Body weight (kg)67.8±12.068 (42–96)
Body surface area (m2)1.79±0.191.79 (1.35–2.22)
Body mass index (kg/m2)23.3±3.123 (17–32)
Total liver volume (mL)1,452.4±308.11,428 (842–2,416)
Standardized total liver volume (mL/m2)810.7±134.8801 (516.3–1,260.4)
Skeletal muscle area at the L3 level (cm2)152.2±36.5154 (85.3–223.1)
L3 skeletal muscle index (cm2/m2)51.9±9.651.2 (35.9–75.3)

SD, standard deviation..



The median values of BSA, L3SMI, and TLV were 1.79 m2, 51.2 cm2/m2, and 1,428 mL, respectively. The median value of TLV per BSA (standardized TLV) was 801 mL/m2.

The correlation between TLV and L3SMI is depicted in Fig. 1. The correlation analysis showed that the correlation coefficient r was 0.612 (95% CI=0.473–0.722; p<0.001) and the Spearman correlation coefficient ρ was 0.641 (p<0.001). The regression equation for SLV was as follows: SLV (mL)=19.7×L3SMI (cm2/m2) +428.4 (R2=0.375, p<0.001).

Figure 1. A scatter plot of the standard liver volume formula using the skeletal muscle index at the third lumbar spine (L3SMI).

The correlation between TLV and BSA is depicted in Fig. 2. The correlation analysis showed that the correlation coefficient r was 0.644 (95% CI=0.513–0.746; p<0.001) and the Spearman correlation coefficient ρ was 0.657 (p<0.001). The regression equation for SLV was as follows: SLV (mL)=1,021.7×BSA (m2) —372.9 (R2=0.415, p<0.001).

Figure 2. A scatter plot of the standard liver volume formula using the body surface area.

The difference between the actual TLV and formula-derived TLV was analyzed. The mean difference was —2.7%±17.4% (95% CI=—6.2–0.74) for the L3SMI-based formula and 2.6%±16.5% (95% CI=—5.6–0.69) for the SLV-based formula (Fig. 3). These differences did not show a significant difference (p=0.955).

Figure 3. Comparison of volume difference percentages between the skeletal muscle index at the third lumbar spine (L3SMI)-, body surface area (BSA)-, and their combination-based standard liver volume (SLV) to the actual total liver volume (TLV).

Considering that the L3SMI- and SLV-based formulae resulted in similar values of SLV, the following formula for their arithmetic mean was obtained: SLV (mL)=510.9×BSA (m2) +9.9×L3SMI (cm2/m2) +27.8. The mean difference from the individual TLV was —2.6%±15.9% (95% CI=—5.8–0.51) (Fig. 3), which was also comparable to that for the SLV-based formula (p=0.977) and that for the L3SMI-based formula (p=0.975).

The correlation between L3SMI and BMI is depicted in Fig. 4. The correlation analysis showed that the correlation coefficient r was 0.546 (95% CI=0.392–0.671; p<0.001) and the Spearman correlation coefficient ρ was 0.589 (p<0.001). The regression equation for SLV was as follows: BMI (kg/m2)=0.174×L3SMI (cm2/m2) +14.2 (R2=0.298, p<0.001).

Figure 4. Scatter plots for correlation between the body mass index and skeletal muscle index at the third lumbar spine (L3SMI).

DISCUSSION

Moore than 16 formulae for SLV calculation have been proposed following its first introduction in 1995 [1]. We presented our first SLV formula in 1997 [10] and the second formula in 2015 [11]. In the field of LDLT, the concept of SLV was adopted to estimate the native liver volume in patients with advanced liver cirrhosis. We previously reported that comparisons between the pre-existing formula-based SLVs and actual individual TLVs showed volume errors of more than 10%, regardless of the SLV formula type, primarily due to wide inter-individual variability of TLVs [2,11-14]. Such large errors in SLV estimation based on the BSA-based formulae are natural because BSA is greatly influenced by obesity, BMI, sex, aging changes, and other factors.

To improve the accuracy of SLV prediction, we testified the L3SMI-based formula for SLV calculation in our previous study [3]. SLV calculation with the L3SMI-based formula was not superior to that with the conventional BSA-based formulae. In contrast, there is a possibility that L3SMI may more reliably reflect the lean body mass than BSA. Thus, in the present study, we aimed to validate the reliability of a L3SMI-formula for calculating the SLV using a newly established living liver donor cohort. Unlike the results of our previous study, the present study revealed that SLV estimation using the L3SMI-based formula was statistically comparable to that using the BSA-based formula. Considering that the L3SMI- and BSA-based formulae resulted in similar values of SLV, a formula for the arithmetic mean of L3SMI- and SLV-based formulae was derived, which showed a mean difference of —2.6%±15.9% from the individual TLV, which was also comparable to that for the SLV-based formula (p=0.977) and that for the L3SMI-based formula (p=0.975). Considering that the L3SMI- and SLV-based formulae resulted in similar values of SLV, a new formula for their arithmetic mean was derived as follows: SLV (mL)=510.9×BSA (m2) +9.9×L3SMI (cm2/m2) +27.8. The mean difference from the individual TLV was —2.6%±15.9%, which was also comparable to that for the SLV-based formula (2.6%±16.5%) and that for the L3SMI-based formula (—2.7%±17.4%). This new concept of SLV calculation using both BSA and L3SMI seems to deserve further validation studies.

L3SMI has been frequently studied as a surrogate marker of sarcopenia. Sarcopenia is defined as low L3SMI (lower than 41 cm2/m2 for women and lower than 53 cm2/m2 for men in Western countries) [15]. L3SMI has been found to be clinically predictive and associated with clinical endpoints, such as survival and length of hospitalization in various patient populations including post-liver transplantation and in various cancer types [4-8,16-18]. In contrast, there is a significant difference in body dimensions between healthy individuals in the Western and Eastern countries, with the latter having less muscle mass. The reference values of L3SMI for the definition of sarcopenia in the Korean population have not yet been proposed [19]. According to the Western country criteria for sarcopenia, the majority of our living donors were classified as sarcopenic.

Aging processes are inevitably accompanied by structural and functional changes in vital organs. Skeletal muscle, which accounts for 40% of the total body weight, deteriorates quantitatively and qualitatively with aging. Sarcopenia is a condition characterized by significant loss of muscle mass and strength. It is related to subsequent frailty and instability in the elderly population. Because muscle tissues have multiple functions, sarcopenia is closely related to various adverse health outcomes. Different prevalence and clinical implications of sarcopenia are highlighted by each definition. Discordances among these indices have emerged as an issue in defining sarcopenia. A unifying definition for sarcopenia has not yet been attained [20].

In the field of LDLT, sarcopenia can be a confounding variable for calculation of SLV. An international study investigated whether liver transplant candidates with sarcopenia are at an increased risk of receiving an inappropriate SLV estimation by the standard body weight (BW)-derived SLV formula [21]. Non-BW-SLV estimation formulas were tested in 262 LDLT donors and compared to the standard BW-SLV formula. The anthropometric parameters used were the thoracic width (TW-SLV) and thoraco-abdominal circumference (TAC-SLV). Subsequently, sarcopenic and non-sarcopenic LDLT candidates were compared in terms of estimated BW-SLV and non-BW-SLV. In donors, TW-SLV showed comparable concordance with CT scan-measured TLV as BW-SLV. The performance of TAC-SLV was low. In recipients, the prevalence of pretransplant sarcopenia was 30.4%. Sarcopenic patients were attributed a significantly lower BW-SLV than non-sarcopenic patients, despite comparable TW-SLV, age, body height, and gender prevalence. As a result, sarcopenic patients received a graft with a statistically lower weight at organ procurement and more frequently developed a small-for-size syndrome. The authors suggested that, in sarcopenic patients, BW-SLV formulas are affected by high risk of SLV underestimation, thus exposing them to increased risk of posttransplant small-for-size syndrome [21].

This study has a limitation worth noting. This was a retrospective single-center study with a relatively small number of samples. Further validation studies with a high number of healthy individuals are necessary to obtain more reliable results.

In conclusion, the results of this study suggest that the reliability of SLV calculation with the L3SMI-based formula was not superior to that of SLV calculation with the BSA-based formula. The formula of SLV calculation using both BSA and L3SMI seems to deserve further validation studies.

FUNDING

There was no funding related to this study.

CONFLICT OF INTEREST

All authors have no conflicts of interest to declare.

AUTHORS’ CONTRIBUTIONS

Conceptualization: AHA, JIP, SH. Data curation: All. Methodology: AHA, YKC, SH. Visualization: AHA, JIP, SH. Writing - original draft: All. Writing - review & editing: All.

Fig 1.

Figure 1.A scatter plot of the standard liver volume formula using the skeletal muscle index at the third lumbar spine (L3SMI).
Annals of Liver Transplantation 2022; 2: 28-33https://doi.org/10.52604/alt.22.0014

Fig 2.

Figure 2.A scatter plot of the standard liver volume formula using the body surface area.
Annals of Liver Transplantation 2022; 2: 28-33https://doi.org/10.52604/alt.22.0014

Fig 3.

Figure 3.Comparison of volume difference percentages between the skeletal muscle index at the third lumbar spine (L3SMI)-, body surface area (BSA)-, and their combination-based standard liver volume (SLV) to the actual total liver volume (TLV).
Annals of Liver Transplantation 2022; 2: 28-33https://doi.org/10.52604/alt.22.0014

Fig 4.

Figure 4.Scatter plots for correlation between the body mass index and skeletal muscle index at the third lumbar spine (L3SMI).
Annals of Liver Transplantation 2022; 2: 28-33https://doi.org/10.52604/alt.22.0014

Table 1. Demographic and anthropometric profiles of 100 living donors

DemographicMean±SDMedian (range)
Age (yr)35.6±6.936 (18–59)
Height (cm)170.4±9.2170 (152–191)
Body weight (kg)67.8±12.068 (42–96)
Body surface area (m2)1.79±0.191.79 (1.35–2.22)
Body mass index (kg/m2)23.3±3.123 (17–32)
Total liver volume (mL)1,452.4±308.11,428 (842–2,416)
Standardized total liver volume (mL/m2)810.7±134.8801 (516.3–1,260.4)
Skeletal muscle area at the L3 level (cm2)152.2±36.5154 (85.3–223.1)
L3 skeletal muscle index (cm2/m2)51.9±9.651.2 (35.9–75.3)

SD, standard deviation.


References

  1. Urata K, Kawasaki S, Matsunami H, Hashikura Y, Ikegami T, Ishizone S, et al. Calculation of child and adult standard liver volume for liver transplantation. Hepatology 1995;21:1317-1321.
    Pubmed CrossRef
  2. Pomposelli JJ, Tongyoo A, Wald C, Pomfret EA. Variability of standard liver volume estimation versus software-assisted total liver volume measurement. Liver Transpl 2012;18:1083-1092.
    Pubmed CrossRef
  3. Yang G, Hwang S, Song GW, Jung DH. Comparison of skeletal muscle index-based formula and body surface area-based formula for calculating standard liver volume. Ann Hepatobiliary Pancreat Surg 2021;25:192-197.
    Pubmed KoreaMed CrossRef
  4. Fearon K, Strasser F, Anker SD, Bosaeus I, Bruera E, Fainsinger RL, et al. Definition and classification of cancer cachexia: an international consensus. Lancet Oncol 2011;12:489-495.
    CrossRef
  5. Montano-Loza AJ, Meza-Junco J, Baracos VE, Prado CM, Ma M, Meeberg G, et al. Severe muscle depletion predicts postoperative length of stay but is not associated with survival after liver transplantation. Liver Transpl 2014;20:640-648.
    Pubmed CrossRef
  6. Shen W, Punyanitya M, Wang Z, Gallagher D, St-Onge MP, Albu J, et al. Total body skeletal muscle and adipose tissue volumes: estimation from a single abdominal cross-sectional image. J Appl Physiol (1985) 2004;97:2333-2338.
    Pubmed CrossRef
  7. Golse N, Bucur PO, Ciacio O, Pittau G, Sa Cunha A, Adam R, et al. A new definition of sarcopenia in patients with cirrhosis undergoing liver transplantation. Liver Transpl 2017;23:143-154.
    Pubmed CrossRef
  8. Prado CM, Lieffers JR, McCargar LJ, Reiman T, Sawyer MB, Martin L, et al. Prevalence and clinical implications of sarcopenic obesity in patients with solid tumours of the respiratory and gastrointestinal tracts: a population-based study. Lancet Oncol 2008;9:629-635.
    CrossRef
  9. Mosteller RD. Simplified calculation of body-surface area. N Engl J Med 1987;317:1098.
    Pubmed CrossRef
  10. Hwang S, Lee SG, Lee YJ, Park KM, Jeon HB, Kim PN, et al. Calculation of standard liver volume of Korean adults. Korean J Hepatobiliary Pancreat Surg 1997;1:59-65.
  11. Hwang S, Ha TY, Song GW, Jung DH, Ahn CS, Moon DB, et al. Quantified risk assessment for major hepatectomy via the indocyanine green clearance rate and liver volumetry combined with standard liver volume. J Gastrointest Surg 2015;19:1305-1314.
    Pubmed CrossRef
  12. Hashimoto T, Sugawara Y, Tamura S, Hasegawa K, Kishi Y, Kokudo N, et al. Estimation of standard liver volume in Japanese living liver donors. J Gastroenterol Hepatol 2006;21:1710-1713.
    Pubmed CrossRef
  13. Yuan D, Lu T, Wei YG, Li B, Yan LN, Zeng Y, et al. Estimation of standard liver volume for liver transplantation in the Chinese population. Transplant Proc 2008;40:3536-3540.
    Pubmed CrossRef
  14. Poovathumkadavil A, Leung KF, Al Ghamdi HM, Othman Iel H, Meshikhes AW. Standard formula for liver volume in Middle Eastern Arabic adults. Transplant Proc 2010;42:3600-3605.
    Pubmed CrossRef
  15. Martin L, Birdsell L, Macdonald N, Reiman T, Clandinin MT, McCargar LJ, et al. Cancer cachexia in the age of obesity: skeletal muscle depletion is a powerful prognostic factor, independent of body mass index. J Clin Oncol 2013;31:1539-1547.
    Pubmed CrossRef
  16. Kim EY, Kim YS, Park I, Ahn HK, Cho EK, Jeong YM. Prognostic significance of CT-determined sarcopenia in patients with small-cell lung cancer. J Thorac Oncol 2015;10:1795-1799.
    Pubmed CrossRef
  17. Kim EY, Lee HY, Kim YS, Park I, Ahn HK, Cho EK, et al. Prognostic significance of cachexia score assessed by CT in male patients with small cell lung cancer. Eur J Cancer Care (Engl) 2018;27:e12695.
    Pubmed CrossRef
  18. Zheng ZF, Lu J, Zheng CH, Li P, Xie JW, Wang JB, et al. A novel prognostic scoring system based on preoperative sarcopenia predicts the long-term outcome for patients after R0 resection for gastric cancer: experiences of a high-volume center. Ann Surg Oncol 2017;24:1795-1803.
    Pubmed CrossRef
  19. Kim KM, Jang HC, Lim S. Differences among skeletal muscle mass indices derived from height-, weight-, and body mass index-adjusted models in assessing sarcopenia. Korean J Intern Med 2016;31:643-650.
    Pubmed KoreaMed CrossRef
  20. Merrill Z, Perera S, Chambers A, Cham R. Age and body mass index associations with body segment parameters. J Biomech 2019;88:38-47.
    Pubmed CrossRef
  21. Pravisani R, Hidaka M, Baccarani U, Ono S, Isola M, Kugiyama T, et al. Effect of pre-transplant sarcopenia on the estimation of standard liver volume in living-donor liver transplant candidates: risk factor for post-transplant small-for-size syndrome? A retrospective study. Transpl Int 2020;33:1282-1290.
    Pubmed CrossRef
The Korean Liver Transplantation Society

Vol.2 No.1
May, 2022

pISSN 2765-5121
eISSN 2765-6098

Stats or Metrics

Share this article on :

  • line