Comparison of different 2D muscle indexes measured at the level of the 3rd lumbar vertebra in survival prediction in patients with renal cell carcinoma.

BACKGROUND: Low computed tomography (CT)-determined muscle mass, commonly determined with height-adjusted muscle indexes (MIs), predicts worse survival in several cancers and has been suggested as a prognostic assessment tool. Although several MIs measured at the level of the 3rd lumbar vertebra (L3) are commonly used, it remains unestablished how different L3-determined MIs perform in survival prognostication compared to each other. The objective of this study was to investigate the performance of different MIs for survival prognostication in renal cell carcinoma (RCC). METHODS: We retrospectively enrolled 214 consecutive patients with RCC. We determined three L3-MIs (psoas muscle index (PMI), psoas muscle index and erector spinae index (PMI+ESI), and whole skeletal muscle index (SMI)) from preoperative CT scans. Categorization of those with low and normal muscle mass was based on the Youden Index sex-specific MI cut-offs. We determined sensitivity, specificity, and accuracy metrics for predicting 1-year, 5-year, and overall survival (OS) using Cox regression models. RESULTS: Low PMI, PMI+ESI, and SMI significantly predicted decreased 1-year, 5-year, and OS in uni- and multivariate models. PMI+ESI and SMI were more accurate than PMI in males, and PMI and PMI+ESI were more accurate than SMI in females in the prediction of 1-year survival. However, there were no differences in accuracies between MIs in 5-year and OS prediction. INTERPRETATION: PMI+ESI performed well overall in short-term prognostication, but there were no differences between the MIs in long-term prognostication. We recommend the use of PMI+ESI for muscle evaluation, particularly when SMI cannot be evaluated.

Computed Tomography-Assessed Sarcopenia Predicts Mortality in Kidney Transplant Candidates.

OBJECTIVES: Sarcopenia is common in chronic kidney disease and associated with increased mortality. We investigated the prevalence of sarcopenia, defined as low muscle mass by the psoas muscle index, in endstage renal disease patients on waiting lists for kidney transplant and determined its association with prognostic nutritional index, C-reactive protein-toalbumin ratio, cardiovascular events, and mortality. MATERIALS AND METHODS: Our study included 162 patients with end-stage renal disease and 87 agematched healthy controls. We calculated nutritional status as follows: prognostic nutritional index = (10 × albumin [g/dL]) + (0.005 × total lymphocyte count (×103/µL]) and C-reactive protein-to-albumin ratio. We gathered demographic and laboratory data from medical records. RESULTS: Patients with end-stage renal disease had a mean age of 44.7 ± 14.2 years; follow-up time was 3.37 years (range, 0.35-9.60 y). Although patients with endstage renal disease versus controls had higher prevalence of sarcopenia (16.7% vs 3.4%; P = .002) and C-reactive protein-to-albumin ratio (1.47 [range, 0.12-37.10] vs 0.74 [range, 0.21-10.20]; P < .001), prognostic nutritional index was lower (40 [range, 20.4-52.2] vs 44 [range, 36.1-53.0]; P < .001). In patients with end-stage renal disease with and without sarcopenia, prognostic nutritional index (P = .005) was lower and C-reactive protein-to-albumin ratio (P = .041) was higher in those with versus those without sarcopenia. Among 67 patients on waiting lists who received kidney transplants, those without sarcopenia had better 5-year patient survival posttransplant than those with sarcopenia (P = .001). Multivariate regression analysis showed sarcopenia and low prognostic nutritional index were independentrisk factors for mortality among patients with end-stage renal disease. CONCLUSIONS: Sarcopenia was ~5 times more frequent in patients with end-stage renal disease than in healthy controls and was positively correlated with the prognostic nutritional index. Sarcopenia was an independent risk factor for mortality in patients on transplant waiting lists.

More than what meets the eye in COVID-19 critical illness: A case report of bilateral femoral neuropathy due to psoas hematomas.

Bilateral femoral neuropathy is rare, especially that caused by bilateral compressive iliopsoas, psoas, or iliacus muscle hematomas. We present a case of bilateral femoral neuropathy due to spontaneous psoas hematomas developed during COVID-19 critical illness. A 41-year-old patient developed COVID-19 pneumonia, and his condition deteriorated rapidly. A decrease in the hemoglobin level prompted imaging studies during his intensive care unit (ICU) stay. Bilateral psoas hematomas were identified as the source of bleeding. Thereafter, the patient complained of weakness in both upper and lower limbs and numbness in the lower limb. He was considered to have critical illness neuropathy and was referred to rehabilitation. Electrodiagnostic testing suggested bilateral femoral neuropathy because of compression due to hematomas developed during the course of his ICU stay. The consequences of iliopsoas hematomas occurring in the critically ill can be catastrophic, ranging from hemorrhagic shock to severe weakness, highlighting the importance of recognizing this entity.

Psoas muscle area is an independent survival prognosticator in patients undergoing surgery for long-bone metastases.

BACKGROUND: Predictive analytics is gaining popularity as an aid to treatment planning for patients with bone metastases, whose expected survival should be considered. Decreased psoas muscle area (PMA), a morphometric indicator of suboptimal nutritional status, has been associated with mortality in various cancers, but never been integrated into current survival prediction algorithms (SPA) for patients with skeletal metastases. This study investigates whether decreased PMA predicts worse survival in patients with extremity metastases and whether incorporating PMA into three modern SPAs (PATHFx, SORG-NG, and SORG-MLA) improves their performance. METHODS: One hundred eighty-five patients surgically treated for long-bone metastases between 2014 and 2019 were divided into three PMA tertiles (small, medium, and large) based on their psoas size on CT. Kaplan-Meier, multivariable regression, and Cox proportional hazards analyses were employed to compare survival between tertiles and examine factors associated with mortality. Logistic regression analysis was used to assess whether incorporating adjusted PMA values enhanced the three SPAs' discriminatory abilities. The clinical utility of incorporating PMA into these SPAs was evaluated by decision curve analysis (DCA). RESULTS: Patients with small PMA had worse 90-day and 1-year survival after surgery (log-rank test p < 0.001). Patients in the large PMA group had a higher chance of surviving 90 days (odds ratio, OR, 3.72, p = 0.02) and 1 year than those in the small PMA group (OR 3.28, p = 0.004). All three SPAs had increased AUC after incorporation of adjusted PMA. DCA indicated increased net benefits at threshold probabilities >0.5 after the addition of adjusted PMA to these SPAs. CONCLUSIONS: Decreased PMA on CT is associated with worse survival in surgically treated patients with extremity metastases, even after controlling for three contemporary SPAs. Physicians should consider the additional prognostic value of PMA on survival in patients undergoing consideration for operative management due to extremity metastases.

Psoas Muscle Area as a Predictor of Transcatheter Aortic Valve Implantation Outcomes.

BACKGROUND: Frailty is a well-recognised predictor of outcomes after transcatheter aortic valve implantation (TAVI). Psoas muscle area (PMA) is a surrogate marker for sarcopaenia and is a validated assessment tool for frailty. The objective of this study was to examine frailty as a predictor of outcomes in TAVI patients and assess the prognostic usefulness of adding PMA to established frailty assessments. METHODS: Frailty assessments were performed on 220 consecutive patients undergoing TAVI. These assessments used four markers (serum albumin, handgrip strength, gait speed, and a cognitive assessment), which were combined to form a composite frailty score. Preprocedural computed tomography scans were used to calculate cross-sectional PMA for each patient. The primary outcomes were all-cause mortality at 1-year and post-procedure length of hospital stay. RESULTS: Frailty status, as defined by the composite frailty score, was independently predictive of length of hospital stay (p=0.001), but not predictive of 1-year mortality (p=0.161). Albumin (p=0.036) and 5-metre walk test (p=0.003) were independently predictive of 1-year mortality. The PMA, when adjusted for gender, and normalised according to body surface area, was not predictive of 1-year mortality. Normalised PMA was associated with increased post-procedure length of stay within the female population (p=0.031). CONCLUSIONS: A low PMA is associated with increased length of hospital stay in female TAVI patients but does not provide additional predictive value over traditional frailty scores. The PMA was not shown to correlate with TAVI-related complications or 1-year mortality.

Correlation between preoperative CT scan of the paraspinal, psoas, and gluteus muscles and postoperative ambulatory status in patients with femoral neck fractures.

BACKGROUND: This study aimed to investigate the relationship between femoral neck fractures and sarcopenia. METHODS: This was a retrospective analysis of 92 patients with femoral neck fractures, from September 2017 to March 2020, who were classified into high ambulatory status (HG) and low ambulatory status (LG) groups. Ambulatory status was assessed before surgery, one week after surgery, at discharge, and during the final follow-up. To evaluate sarcopenia, muscle mass and fatty degeneration of the muscles were measured using preoperative CT. An axial slice of the superior end of the L5 vertebra was used to evaluate the paraspinal and psoas muscles, a slice of the superior end of the femoral head for the gluteus maximus muscle, and a slice of the inferior end of the sacroiliac joint for the gluteus medius muscle. The degeneration of the muscles was evaluated according to the Goutallier classification. RESULTS: The cross-sectional area of the gluteus medius and paraspinal muscles was significantly correlated with ambulatory status before the injury, at discharge, and during the final follow-up. CONCLUSIONS: Measurement of the gluteus medius and paraspinal muscles has the potential to evaluate sarcopenia and predict ambulatory status after femoral neck fractures.

Oblique Lumbar Interbody Fusion at L5-S1 Segment Through an Approach Between the Psoas Muscle and the Great Vessels.

Over the years, the oblique lateral interbody fusion (OLIF) technique has gained significant recognition for treating various spinal conditions in lumbar segments L2-L5. However, the adoption of OLIF for the L5-S1 segment has not been widely embraced by the spinal surgery community, given that significant concerns remain regarding the applicability of OLIF for lumbosacral fusion. In this study, a cohort of 20 patients underwent interbody fusion at the L5-S1 level using the OLIF technique through a single retroperitoneal oblique approach positioned between the Psoas muscle and the great vessels. The procedure involved discectomy and endplate preparation accomplished through a surgical window created on the anterolateral side of the L5-S1 disc. For secure interbody fusion cage placement, a supplementary cage insertion approach was employed. All patients were followed up for a minimum of 12 months. The mean preoperative visual analog scale (VAS) score for lower back pain was 6.3 ± 1.5 and experienced a significant reduction to 1.2 ± 0.8 at 12 months. The VAS score for lower limb pain significantly decreased from 5.6 ± 1.4 preoperatively to 0.8 ± 0.3 at 12 months after the surgery. Furthermore, the preoperative Oswestry disability index (ODI) improved from 82.4% ± 16.2% to 8.1% ± 2.0% at 12 months. Radiographic evaluations after surgery confirmed improved lumbosacral junction reconstruction for all patients. At the final follow-up, successful bony fusion was observed in all cases. Based on these findings, the OLIF technique for L5-S1 fusion represents an attainable approach for lumbosacral reconstruction. The procedure's success hinges on a comprehensive preoperative plan and precise intraoperative techniques.

Reliability of Ultrasound Shear Wave Elastography for Evaluating Psoas Major and Quadratus Lumborum Stiffness: Gender and Physical Activity Effects.

OBJECTIVE: We aimed to assess the reliability of quantifying psoas major (PM) and quadratus lumborum (QL) stiffness with ultrasound shear wave elastography (SWE), and to explore the effects of gender and physical activity on muscle stiffness. METHODS: Fifty-two healthy participants (18-32 y) were recruited. To determine reliability, 29 of them underwent repeated SWE measurements of PM and QL stiffness by an operator on the same day. The intra-class correlation coefficients (ICC3,1), standard error of measurement (SEM) and minimal detectable change with 95% confidence interval (MDC95) were calculated. The rest participants underwent a single measurement. Two-way MANCOVA was conducted for the effects of gender and physical activity on muscle stiffness. RESULTS: The observed reliability for PM (ICC3,1 = 0.89-0.92) and QL (ICC3,1 = 0.79-0.82) were good-to-excellent and good, respectively. The SEM (kPa) was 0.79-1.03 and 1.23-1.28, and the MDC95 (kPa) was 2.20-2.85 and 3.41-3.56 for PM and QL, respectively. After BMI adjustment, both gender (PM: F = 10.15, p = 0.003; QL: F = 18.07, p < 0.001) and activity level (PM: F = 5.90, p = 0.005; QL: F = 6.33, p = 0.004) influenced muscle stiffness. The female and inactive groups exhibited higher stiffness in both muscles. CONCLUSION: SWE is reliable for quantifying the stiffness of PM and QL. Female and physical inactivity may elevate PM and QL stiffness, underscoring the importance of accounting for these factors in muscle stiffness investigations. Larger prospective studies are needed to further elucidate their effects.

Psoas muscle area is associated with prognosis in elderly patients with hip fracture.

INTRODUCTION: Sarcopenia is a key predictor of prognosis in patients with hip fractures. This study utilized computed tomography (CT) scan (1) to determine the association between psoas muscle cross-sectional area (CSA) and mortality, along with other muscles, and (2) to confirm the correlation between muscle CSA and appendicular lean mass (ALM) measured using DXA in elderly patients with hip fracture. MATERIALS AND METHODS: Patients who were aged ≥ 50 years and underwent surgical treatment for hip fracture were eligible for this study. After a series of exclusion criteria, 217 female patients were included. Patient data, including clinical characteristics, such as body mass index (BMI), CSA, and ALM, were retrospectively collected. The Kaplan-Meier survival method and Cox proportional hazards regression analysis were used for the statistical analyses. The correlation between CSA/BMI and ALM was also assessed. RESULTS: Patients in the lowest quartile of psoas muscle CSA/BMI had shorter survival times than those in the other quartiles. When the Cox proportional hazards regression analysis was adjusted for multiple variables, the lowest quartile of the CSA/BMI of the psoas was a risk factor for mortality. The CSA/BMI of the psoas showed the highest correlation coefficient. The CSA/BMI ratio of the other muscles showed a moderately positive correlation with ALM. CONCLUSION: The CSA of the psoas is associated with prognosis in elderly patients with hip fractures and shows a moderately positive correlation with ALM. Hence, the CSA of psoas is useful for predicting survival and muscle mass in elderly patients with hip fractures.

Computed tomography-based abdominal sarcopenic indices and bio-impedance analysis-based skeletal muscle mass index in hemodialyzed patients.

BACKGROUND AND AIMS: Information about muscle wasting in hemodialyzed patients evaluated using computed tomography (CT) is limited. The present study aimed to examine the relationships between CT-based abdominal sarcopenic indices and bio-impedance analysis (BIA)-based skeletal muscle mass index (SMMI) in these patients. METHODS: A total of 100 consecutive maintenance hemodialyzed patients who underwent CT and BIA were included. The psoas muscle index (PMI), paraspinous muscle index (PSMI), and abdominal skeletal muscle index (ASMI) were calculated by adjusting each muscle area to the height square. The psoas muscle thickness per height (PMTH) was measured using a single cross-sectional CT image obtained at the level of the third lumbar vertebra. The relationships between these CT-based sarcopenic indices and the BIA-based SMMI were examined. Moreover, the diagnostic values of these CT-based indices for BIA-defined muscle wasting (defined by the sex-specific SMMI: males, <7.0 kg/m2; females, <5.7 kg/m2) were investigated. RESULTS: The PMI, PMTH, PSMI, and ASMI were significantly correlated with the SMMI (r = 0.678, 0.760, 0.708, and 0.785, respectively; p < 0.0001 for all). Twenty-eight patients with reduced muscle mass determined by BIA were identified. After age-sex adjustment, a multivariate logistic regression analysis revealed that the C-statistics of the PMI, PMTH, PSMI, and ASMI for the diagnosis of low muscle mass were 0.863 (p = 0.0099), 0.870 (p = 0.013), 0.891 (p = 0.040), and 0.950 (reference), respectively. CONCLUSIONS: CT-based abdominal sarcopenic indices presented here may be useful for evaluating muscle wasting in hemodialyzed patients; the ASMI may be the most recommended sarcopenic index for such evaluations.

Association between reduced muscle mass and poor prognosis of biliary sepsis.

Sepsis is a life-threatening disease, contributing to significant morbidity and mortality. This study aimed to investigate the association between low muscle mass and the prognosis of patients with biliary sepsis, focusing on outcomes such as length of hospital stay (LOS), intensive care unit (ICU) admission, and in-hospital mortality. This retrospective, single-center, observational study included adult patients with biliary sepsis who visited the emergency department between January 2016 and December 2021. Low muscle mass was assessed using the psoas muscle index (PMI). Using computed tomography imaging, the area of both sides of the psoas muscle at the L3 level was measured, and the PMI, corrected by the patient's height was calculated. The primary outcome was in-hospital mortality, and the secondary outcomes were intensive care unit (ICU) admission, LOS, and 14-day mortality. A total of 745 patients were included in this study. Low muscle mass was defined as a PMI < 421 mm2/m2 for males and < 268 mm2/m2 for females with the lower quartile of PMI according to sex. The cohort was classified into sarcopenic (n = 189) and non-sarcopenic (n = 556) groups. There was a significant association between low muscle mass and in-hospital mortality (odds ratio, 3.81; 95% confidence interval, 1.08-13.47; p < 0.001), while there was no significant association between low muscle mass and ICU admission. In addition, the median LOS in the sarcopenic group (10 [7-14] days) was significantly longer than the median (8 [6-11] days) in the non-sarcopenic group. Low muscle mass was significantly associated with clinical outcomes, particularly in-hospital mortality and LOS, in patients with biliary sepsis.

The psoas muscle index as a useful predictor of total hip arthroplasty outcomes.

INTRODUCTION: The aim of this study is to assess the association between the psoas muscle index (PMI) and total hip arthroplasty (THA) outcomes. This is a critical issue as sarcopenia has been associated with poor patient satisfaction post-THA. MATERIALS AND METHODS: This was a retrospective case-control study of 205 THAs, with a mean follow-up of 3.6 (range, 2.0-5.5) years. Age, sex, serum immune markers, spinopelvic parameters, PMI (quantified as the cross-sectional area of the psoas, bilaterally, at L3 divided by the individual's height squared), and patient-reported outcomes were compared between patients 'with' (n = 118) and 'without' (n = 87) achievement of a minimum clinically important difference (MCID) improvement in the EuroQol 5-Dimension (EQ-5D), post-THA. Logistic regression and receiver operating characteristic curve analyses were used to identify predictive factors. RESULTS: A ≥ MCID improvement in the EQ-5D was associated with the PMI (odds ratio, 0.75; 95% confidence interval, 0.63-0.91; P = 0.028), prognostic nutritional index (odds ratio, 0.85; 95% confidence interval, 0.45-0.94; P = 0.043), and age (odds ratio, 1.09; 95% confidence interval, 1.01-1.18; P = 0.044). After adjusting the PMI threshold to 4.0 cm2/m2 for females and 6.4 cm2/m2 for males, there were significant differences in serum factors (P = 0.041 for albumin and P = 0.016 for a prognostic nutritional index < 40), MCID (P < 0.001 for EQ-5D, P < 0.001 for low back pain, and P = 0.008 for the Hip Disability and Osteoarthritis Outcome Score Joint Replacement score), patient satisfaction (P = 0.003), and T1 pelvic angle (P = 0.030). CONCLUSION: The PMI, which is associated with nutritional status and global sagittal spinal deformity, does predict THA outcomes. Therefore, it can be useful when discussing THA expectations with patients.

Preoperative low muscle mass and early postoperative outcomes in children undergoing living donor liver transplantation: A retrospective study.

Low skeletal muscle mass may develop in children with end-stage liver disease, affecting postoperative outcomes. We retrospectively investigated whether preoperative low muscle mass was associated with early postoperative outcomes in pediatric patients undergoing living donor liver transplantation (LDLT). Electronic medical records of children (age below 12 y) who underwent LDLT between February 1, 2007, and January 31, 2018, were reviewed. The cross-sectional areas of psoas, quadratus lumborum, and erector spinae muscles at the level of fourth-fifth lumbar intervertebral disks were measured using abdominal CT images, divided by the square of the height and were added to obtain the total skeletal muscle index (TSMI). The patients were divided into two groups according to the median TSMI in the second quintile (1859.1 mm 2 /m 2 ). Complications in the early postoperative period (within 30 d after surgery) classified as Clavien-Dindo grade 3 or higher were considered major complications. Logistic regression analyses were performed to determine the association between preoperative low muscle mass and early postoperative outcomes. In the study population of 123 patients (median age, 14 mo; range, 8-38 mo) who underwent LDLT, 29% and 71% were classified in the low (mean TSMI, 1642.5 ± 187.0 mm 2 /m 2 ) and high (mean TSMI 2188.1 ± 273.5 mm 2 /m 2 ) muscle mass groups, respectively. The rates of major complications, mechanical ventilation >96 hours, intensive care unit stay >14 days, hospital stay >30 days, and in-hospital mortality were not significantly different between the 2 groups. Additionally, adverse outcomes according to pediatric end-stage liver disease scores and sex were not significantly different between the 2 groups. In conclusion, preoperative low muscle mass defined by TSMI was not associated with early postoperative outcomes in pediatric patients undergoing LDLT.

Myosteatosis as a novel predictor of new-onset diabetes mellitus after kidney transplantation.

OBJECTIVES: We evaluate the effect of myosteatosis on new-onset diabetes mellitus after kidney transplantation. METHODS: Consecutive patients who had renal transplant between 2006 and 2021 were reviewed, and 219 patients were finally included. Psoas muscle index was used to evaluate sarcopenia and average total psoas density (calculated by computed tomography before surgery) for myosteatosis. We used Cox proportional regression analyses in investigation of whether skeletal muscle depletion before surgery inclusive of sarcopenia and myosteatosis is a new additional predictor of new-onset diabetes mellitus. RESULTS: Median recipient age and body mass index were 45 years and 21.1 kg/m2 , respectively, and 123 patients (56%) were male. Preoperative impaired glucose tolerance was present in 58 patients (27%) and new-onset diabetes mellitus in 30 patients (14%), with median psoas muscle index of 6 cm2 /m2 and average total psoas density of 41 Hounsfield Unit. In multivariate analysis, significant risk factors were body mass index ≥25 kg/m2 (p < 0.01), impaired glucose tolerance (p < 0.01), and average total psoas density < 41.9 Hounsfield Unit (p = 0.03). New-onset diabetes mellitus had incidence rates of 3.7% without risk factors, 10% with a single risk factor, 33% with two, and 60% with three. Patients with new-onset diabetes mellitus were effectively stratified by the number of risk factors (p < 0.01). CONCLUSIONS: Myosteatosis could be a new risk factor used to predict new-onset diabetes mellitus.

Femoral nerve palsy as a complication due to COVID-19 coagulopathy and iliopsoas muscle hematoma - case report.

BACKGROUND: COVID-19 (Coronavirus disease 2019) pandemic is the main medical problem around the world from the end of 2019. We found until now many symptoms of this disease, but one of the most problematic was thrombosis. Wide recommendation on COVID-19 treatment was pharmacological thromboprophylaxis. In some papers we found that clinicians face the problem of bleeding in those patients. Is still unknown that coronavirus could led to the coagulopathy. CASE PRESENTATION: We described case report of patient who with COVID-19 disease present femoral nerve palsy caused by the iliopsoas hematoma. There were no deviations in coaguology parameters, patient got standard thromboprophylaxis, besides above probably COVID-19 was risk factor of hematoma formation. Non-operative treatment was applied, thrombophylaxis was discontinued. In the follow up in the radiological exam we saw reduction of the haematoma and patient report decrease of symptoms. CONCLUSIONS: We should assess individually patient with COVID-19 according to thrombosis risk factors. Probably we should be more careful in ordering thrombophylaxis medications in COVID-19 patients.

Computed tomography measured epicardial adipose tissue and psoas muscle attenuation: new biomarkers to predict major adverse cardiac events and mortality in patients with heart disease and critically ill patients. Part II: Psoas muscle area and density.

Sarcopenia is a syndrome characterised by loss of skeletal muscle mass, loss of muscle quality, and reduced muscle strength, resulting in low performance. Sarcopenia has been associated with increased mortality and complications after medical interventions. In daily clinical practice, sarcopenia is assessed by clinical assessment of muscle strength and performance tests and muscle mass quantification by dual-energy X-ray absorptio-metry (DXA) or bioelectrical impedance analysis (BIA). Assessment of the skeletal muscle quantity and quality obtained by abdominal computed tomography (CT) has gained interest in the medical community, as abdominal CT is performed for various medical reasons, and quantification of the psoas and skeletal muscle can be performed without additional radiation load and dye administration. The definitions of CT-derived skeletal muscle mass quantification are briefly reviewed: psoas muscle area (PMA), skeletal muscle area (SMA), and transverse psoas muscle thickness (TPMT). We explain how CT attenuation coefficient filters are used to determine PMA and SMA, resulting in the psoas muscle index (PMI) and skeletal muscle index (SMI), respectively, after indexation to body habitus. Psoas muscle density (PMD), a biomarker for skeletal muscle quality, can be assessed by measuring the psoas muscle CT attenuation coefficient, expressed in Hounsfield units. The concept of low-density muscle (LDM) is explained. Finally, we review the medical literature on PMI and PMD as predictors of adverse outcomes in patients undergoing trauma or elective major surgery, transplantation, and in patients with cardiovascular and internal disease. PMI and PMD are promising new biomarkers predicting adverse outcomes after medical interventions.

Potential of whole-body dual-energy X-ray absorptiometry to predict muscle size of psoas major, gluteus maximus and back muscles.

BACKGROUND: Measurement of trunk muscle cross-sectional area (CSA) using axial magnetic resonance imaging (MRI) is considered clinically meaningful for understanding several spinal pathologies, such as low back pain and spinal sagittal imbalance. However, it remains unclear whether trunk muscle mass (TMM) measured using dual-energy X-ray absorptiometry (DXA) can predict the trunk muscle CSA. The aim of this study is to determine if DXA-derived TMM is associated and predicts with CSA of paraspinal muscles and gluteus maximus measured using MRI in healthy volunteers. METHODS: A total of 48 healthy volunteers underwent whole-body DXA and MRI of the spinopelvic region. The CSA of the psoas major, back muscles, and gluteus maximus were measured on axial MRI. Correlations and linear regressions between the TMM measured using DXA and the CSA of each musculature were investigated. RESULTS: There was a weak correlation between TMM and CSA of the psoas major in men (r = 0.39, P = 0.0678), and the linear regression was y = 301.74x - 401.24 (R2 = 0.2976, P = 0.0070). A moderate correlation was found in women (r = 0.58, P = 0.0021), and the linear regression was y = 230.21x - 695.29 (R2 = 0.4445, P = 0.0003). Moderate correlations were observed between TMM and CSA of the back muscles in both men (r = 0.63, P = 0.0012) and women (r = 0.63, P = 0.0007), the linear regression was y = 468.52x + 3688.5 (R2 = 0.5505, P < 0.0001) in men and y = 477.39x + 2364.1 (R2 = 0.564, P < 0.0001) in women. There was a strong correlation between TMM and CSA of the gluteus maximus in men (r = 0.72, P < 0.0001), and the linear regression was y = 252.69x - 880.5 (R2 = 0.6906, P < 0.0001). A moderate correlation was found in women (r = 0.69, P < 0.0001), and the linear regression was y = 230.74x - 231.32 (R2 = 0.6542, P < 0.0001). CONCLUSIONS: The DXA-derived TMM was able to predict the CSA of the psoas major, back muscles, and gluteus maximus, and significantly correlated with the CSA of the back muscles and gluteus maximus. It might be a safer and cheaper alternative for evaluating the size of the back muscles and gluteus maximus.

Increase of radiologically determined muscle area in patients with liver cirrhosis after transjugular intrahepatic portosystemic shunt.

Sarcopenia is common in patients with liver cirrhosis and related to higher mortality. Implantation of a transjugular intrahepatic portosystemic shunt (TIPS) is a feasible method for reducing cirrhosis-related portal hypertension, but also possible improvement of the patient`s muscle status. We aimed to analyze changes in muscle quantity and prevalence of sarcopenia after TIPS. We retrospectively surveyed the muscle status in 52 patients (mean age 54.2 years) before and after TIPS by evaluating skeletal (SMI) and psoas muscle indices (PMI) in CT and MR images. Model for End-Stage Liver Disease (MELD), Freiburg index of post-TIPS survival (FIPS), and their underlying laboratory parameters (e.g., Albumin) were analyzed. Prevalence of sarcopenia was 84.6%. After a median follow-up of 16.5 months after TIPS, SMI (0.020) and PMI (p < 0.001) increased, and sarcopenia decreased by 14.8% (0.109). MELD and PMI after TIPS were negatively correlated (r = - 0.536, p < 0.001). Albumin levels increased in patients with increased SMI after TIPS (p = 0.022). Confirming the positive impact of TIPS implantation on muscle indices in patients with liver cirrhosis, we found indications for improved survival and possible indications for altered metabolism with increased albumin levels in patients with increased muscle quantity.

Fat infiltration of the posterior paraspinal muscles is inversely associated with the fat infiltration of the psoas muscle: a potential compensatory mechanism in the lumbar spine.

BACKGROUND: The function of the paraspinal muscles and especially the psoas muscle in maintaining an upright posture is not fully understood. While usually considered solely as a hip flexor, the psoas muscle and its complex anatomy suggest that the muscle has other functions involved in stabilizing the lumbar spine. The aim of this study is to determine how the psoas muscle and the posterior paraspinal muscles (PPM; erector spinae and multifidus) interact with each other. METHODS: A retrospective review including patients undergoing posterior lumbar fusion surgery between 2014 and 2021 at a tertiary care center was conducted. Patients with a preoperative lumbar magnetic resonance imaging (MRI) scan performed within 12 months prior to surgery were considered eligible. Exclusion criteria included previous spinal surgery at any level, lumbar scoliosis with a Cobb Angle > 20° and patients with incompatible MRIs. MRI-based quantitative assessments of the cross-sectional area (CSA), the functional cross-sectional area (fCSA) and the fat area (FAT) at L4 was conducted. The degree of fat infiltration (FI) was further calculated. FI thresholds for FIPPM were defined according to literature and patients were divided into two groups (< or ≥ 50% FIPPM). RESULTS: One hundred ninetypatients (57.9% female) with a median age of 64.7 years and median BMI of 28.3 kg/m2 met the inclusion criteria and were analyzed. Patients with a FIPPM ≥ 50% had a significantly lower FI in the psoas muscle in both sexes. Furthermore, a significant inverse correlation was evident between FIPPM and FIPsoas for both sexes. A significant positive correlation between FATPPM and fCSAPsoas was also found for both sexes. No significant differences were found for both sexes in both FIPPM groups. CONCLUSION: As the FIPPM increases, the FIPsoas decreases. Increased FI is a surrogate marker for a decrease in muscular strength. Since the psoas and the PPM both segmentally stabilize the lumbar spine, these results may be indicative of a potential compensatory mechanism. Due to the weakened PPM, the psoas may compensate for a loss in strength in order to stabilize the spine segmentally.