Risk Factor Analysis for Fat Infiltration in the Lumbar Paraspinal Muscles in Patients With Lumbar Degenerative Diseases

Introduction This study aimed to investigate factors related to fat infiltration in patients with lumbar degenerative diseases (lumbar disc herniation and/or spinal stenosis), examining a wide range of potential risk variables. Materials and methods We studied consecutive adult patients who underwent posterior lumbar spinal surgery for degenerative diseases at our hospital between July 2013 and June 2017. Preoperative magnetic resonance imaging was used to evaluate the presence or absence of fat infiltration at the level of the L4-5 lumbar paraspinal muscles using Kjaer’s evaluation method. Patients without fat infiltration (0%–10%) were rated as grade 0, grade 1 for moderate fat infiltration (10%–50%), and grade 2 for severe fat infiltration (>50%). Patients were then divided into two groups: Group A (without fat infiltration, grade 0) and Group B (with fat infiltration, grade 1 or 2). Detailed patient clinical data were collected and analyzed. Results A total of 205 consecutive patients were enrolled; 54 (26.3%) patients were assigned to Group A and 151 (73.7%) to Group B. Logistic regression analysis revealed two independent risk factors for fat infiltration of the lumbar paraspinal muscles: female sex and older age (P < .001). Discussion Fat infiltration of the lumbar paraspinal muscles is reported to be associated with the development of pain and dysfunction of the lumbar region and postoperative complications of spinal instrumented fusion surgery. To the best of our knowledge, no previous studies have identified female sex and older age as independent risk factors for fat infiltration in the lumbar paraspinal muscles using multivariate analysis. Conclusions Female sex and older age were independent risk factors for fat infiltration in the lumbar paraspinal muscles. The results of the current study may provide useful information for the study of preventive measures for fat infiltration.

A Novel Mri-Method Allows a Rapid and Robust Assessment of Muscle Quantity and Quality in Hemodialysis Patients.

BackgroundSarcopenia is a prevalent condition in patients on maintenance hemodialysis and associates with mortality. Research using magnetic resonance imaging (MRI) has demonstrated the importance of a proper body size-adjustment in the assessment of muscle mass, and that a muscle composition assessment including measurements of both muscle volume and fat infiltration improves the prediction of comorbidity and survival related to sarcopenia. Such combined muscle composition assessment has not previously been performed in hemodialysis patients.MethodsEleven hemodialysis patients were scanned using whole-body fat and water separated MRI and followed regarding survival and comorbidity for five years. Muscle composition was assessed using AMRA® Researcher. Using data from 9615 UK Biobank participants, sex and BMI-matched muscle volume z-scores and sex-adjusted muscle fat infiltration values were calculated for each patient. These measurements were then used for the calculation of a combined muscle score. Resulting three muscle measurements were associated with survival and comorbidity index.ResultsSix patients exhibited low muscle volume (muscle volume z-score <25th percentile (population wide)), and six patients presented with high muscle fat infiltration (>75th percentile (population wide)). During a 68-months follow-up, five patients died, four were transplanted and two remained on hemodialysis treatment. The combined muscle score was significantly associated with comorbidity index (p<0.05) and was highly predictive of survival (AUROC 0.97).ConclusionsThe combined assessment including both body size-adjusted muscle volume and muscle fat infiltration can be used to analyze muscle composition in hemodialysis patients. MRI based muscle composition assessment reflected comorbidity and predicted survival in hemodialysis patients.

Neoadjuvant Treatment Lowers the Risk of Mesopancreatic Fat Infiltration and Local Recurrence in Patients with Pancreatic Cancer

Background: Survival following surgical treatment of ductal adenocarcinoma of the pancreas (PDAC) remains poor. The recent implementation of the circumferential resection margin (CRM) into standard histopathological evaluation lead to a significant reduction in R0 rates. Mesopancreatic fat infiltration is present in ~80% of PDAC patients at the time of primary surgery and recently, mesopancreatic excision (MPE) was correlated to complete resection. To attain an even higher rate of R0CRM− resections in the future, neoadjuvant therapy in patients with a progressive disease seems a promising tool. We analyzed radiographic and histopathological treatment response and mesopancreatic tumor infiltration in patients who received neoadjuvant therapy prior to MPE. The aim of our study was to evaluate the need for MPE following neoadjuvant therapy and if multi-detector computed tomographically (MDCT) evaluated treatment response correlates with mesopancreatic (MP) infiltration. Method: Radiographic, clinicopathological and survival parameters of 27 consecutive patients who underwent neoadjuvant therapy prior to MPE were evaluated. The mesopancreatic fat tissue was histopathologically analyzed and the 1 mm-rule (CRM) was applied. Results: In the study collective, both the rate of R0 resection R0(CRM−) and the rate of mesopancreatic fat infiltration was 62.9%. Patients with MP infiltration showed a lower tumor response. Surgical resection status was dependent on MP infiltration and tumor response status. Patients with MDCT-predicted tumor response were less prone to MP infiltration. When compared to patients after upfront surgery, MP infiltration and local recurrence rate was significantly lower after neoadjuvant treatment. Conclusion: MPE remains warranted after neoadjuvant therapy. Mesopancreatic fat invasion was still evident in the majority of our patients following neoadjuvant treatment. MDCT-predicted tumor response did not exclude mesopancreatic fat infiltration.

Influence of physical activity level and body adiposity on lumbar multifidus muscle fat infiltration of low back pain individuals

The stability of the spinal column is largely dependent on the integrity of the spinal muscles, especially the multifidus muscle. However, this important role of the multifidus muscle might be compromised due to both mechanical and non-mechanical causes leading to change in its contents, fat deposition and reduction in the cross-sectional area. This study was carried out to determine the influence of physical activity level and body adiposity indices on lumbar multifidus muscle (LMM) fatty infiltration among individuals with low back pain (LBP). This was a cross-sectional study in which 94 participants, male and female samples with non-specific LBP were recruited conveniently and assessed for LMM fat infiltration, pain intensity, functional disability, physical activity and socio-demographic variables. There were positive and moderate correlations between LMM fatty infiltration body mass index (BMI) (r=0.575, p=0.001), waist circumference (WC) (r=0.514, p=0.001) and gender (r=0.409, p=0.001) for normally distributed data using Pearson moment correlation coefficient. For not normally distributed variables, LMM fatty infiltration was moderately and positively correlated with gender (r=0.422, p=0.001), %body fat (r=0.621, p=0.001), visceral fat (r=0.470, p=0.0001), Oswestry Disability Index (ODI) (r=0.238, p=0.021) and visual analogue scale (VAS) (r=0.232, p=0.024) respectively. However, there was a weak negative correlation between LMM fatty infiltration and occupation (r=p=0.046). There were significant differences between male and female multifidus fat infiltration and body adiposity indices. There was a positive relationship between multifidus fatty infiltration and BMI, gender, %body fat, visceral mass, ODI and VAS, while we observed a negative relationship between lumbar multifidus fatty infiltration and occupation. Furthermore, the best correlate of lumbar multifidus % body fat.

An Exploratory Analysis of the Role of Adipose Characteristics in Fulltime Wheelchair Users’ Pressure Injury History

Aim: The goals of this study were 1) to identify the relationship between adipose (subcutaneous and intramuscular) characteristics and pressure injury (PrI) history in wheelchair users and 2) to identify subject characteristics, including biomechanical risk, that are related to adipose characteristics.Materials and Methods: The buttocks of 43 full-time wheelchair users with and without a history of pelvic PrIs were scanned in a seated posture in a FONAR UPRIGHT® MRI. Intramuscular adipose (the relative difference in intensity between adipose and gluteus maximus) and the subcutaneous adipose characteristics (the relative difference in intensity between subcutaneous adipose under and surrounding the ischium) were compared to PrI history and subject characteristics.Results: Participants with a history of PrIs had different subcutaneous fat (subQF) characteristics than participants without a history of PrIs. Specifically, they had significantly darker adipose under the ischium than surrounding the ischium (subQF effect size = 0.21) than participants without a history of PrIs (subQF effect size = 0.58). On the other hand, only when individuals with complete fat infiltration (n = 7) were excluded did individuals with PrI history have more fat infiltration than those without a PrI history. The presence of spasms (μ intramuscular adipose, 95% CI with spasms 0.642 [0.430, 0.855], without spasms 0.168 [−0.116, 0.452], p = 0.01) and fewer years using a wheelchair were associated with leaner muscle (Pearson Corr = −0.442, p = 0.003).Conclusion: The results of the study suggest the hypothesis that changes in adipose tissue under the ischial tuberosity (presenting as darker SubQF) are associated with increased biomechanical risk for pressure injury. Further investigation of this hypothesis, and the role of intramuscular fat infiltration in PrI development, may help our understanding of PrI etiology. It may also lead to clinically useful diagnostic techniques that can identify changes in adipose and biomechanical risk to inform early preventative interventions.

Intramuscular fat in gluteus maximus for different levels of physical activity

We aimed to determine if gluteus maximus (GMAX) fat infiltration is associated with different levels of physical activity. Identifying and quantifying differences in the intramuscular fat content of GMAX in subjects with different levels of physical activity can provide a new tool to evaluate hip muscles health. This was a cross-sectional study involving seventy subjects that underwent Dixon MRI of the pelvis. The individuals were divided into four groups by levels of physical activity, from low to high: inactive patients due to hip pain; and low, medium and high physical activity groups of healthy subjects (HS) based on hours of exercise per week. We estimated the GMAX intramuscular fat content for each subject using automated measurements of fat fraction (FF) from Dixon images. The GMAX volume and lean volume were also measured and normalized by lean body mass. The effects of body mass index (BMI) and age were included in the statistical analysis. The patient group had a significantly higher FF than the three groups of HS (median values of 26.2%, 17.8%, 16.7% and 13.7% respectively, p < 0.001). The normalized lean volume was significantly larger in the high activity group compared to all the other groups (p < 0.001, p = 0.002 and p = 0.02). Employing a hierarchical linear regression analysis, we found that hip pain, low physical activity, female gender and high BMI were statistically significant predictors of increased GMAX fat infiltration.

Comparison of cross-sectional area and fat infiltration of suboccipital muscles between normal dogs and dogs with atlantoaxial instability

Background Atlantoaxial instability (AAI) is primarily a congenital neurological disorder affecting young toy-breed dogs. So far, most studies have focused on bones and ligaments related to AAI, and there are no studies on the suboccipital muscles (SOMs) that occupy a large area from the occipital bone to C2 in dogs. This study evaluated the cross-sectional area (CSA) and fat infiltration of the SOMs using magnetic resonance imaging (MRI), specifically, T1-weighted images, in normal dogs (≤ 5 kg) and AAI dogs. The relationship between the severity of the neurological symptoms of AAI (group A and group B) and the values from MRI was also assessed. Results AAI dogs had significantly smaller CSA (P = 0.029) and greater fat infiltration (P = 0.044) of the SOMs compared to normal dogs. AAI dogs with mild neurological symptoms for a long period (group A) had greater fat infiltration than AAI dogs with severe neurological symptoms (group B) (P = 0.035). Conclusions The muscle changes are most likely due to spinal cord compression resulting from instability; however, the possibility that chronic changes of the muscle may play an additional role in maintaining stability in this region cannot be excluded. This study provides fundamental quantitative information of the SOMs in normal and AAI dogs.

Associations Between Lipoprotein Subfractions and Area and Density of Abdominal Muscle and Intermuscular Adipose Tissue: The Multi-Ethnic Study of Atherosclerosis

Skeletal muscle quantity and quality decrease with older age, which is partly attributed to ectopic fat infiltration and has negative metabolic consequences. To inform efforts to preserve skeletal muscle with aging, a better understanding of biologic correlates of quantity and quality of muscle and intermuscular adipose tissue (IMAT) is needed. We used targeted lipidomics of lipoprotein subfractions among 947 Multi-Ethnic Study of Atherosclerosis participants to provide a detailed metabolic characterization of area and density of abdominal muscle and IMAT. Serum lipoprotein subfractions were measured at the first visit using 1H-Nuclear Magnetic Resonance spectroscopy. Muscle and IMAT area (cm2) and density (Hounsfield units) were estimated at visit 2 or 3 using computed tomography of the total abdominal, locomotion (psoas), and stabilization (paraspinal, oblique, rectus abdominis) muscles. We identified lipoprotein subfractions associated with body composition using linear regression adjusting for demographics, lifestyle, and multiple comparisons. Among 105 lipoprotein subfractions, 24 were associated with total muscle area (absolute standardized regression coefficient range: 0.07–0.10, p-values ≤ 0.002), whereas none were associated with total muscle density. When examining muscle subgroups, 25 lipoprotein subfractions were associated with stabilization muscle area, with associations strongest among the obliques. For total IMAT area, there were 27 significant associations with lipoprotein subfractions (absolute standardized regression coefficient range: 0.09–0.13, p-values ≤ 0.002). Specifically, 27 lipoprotein subfractions were associated with stabilization IMAT area, with associations strongest among the oblique and rectus abdominis muscles. For total IMAT density, there were 39 significant associations with lipoprotein subfractions (absolute standardized regression coefficient range: 0.10–0.19, p-values ≤ 0.003). Specifically, 28 and 33 lipoprotein subfractions were associated with IMAT density of locomotion and stabilization (statistically driven by obliques) muscles, respectively. Higher VLDL (cholesterol, unesterified cholesterol, phospholipids, triglycerides, and apolipoprotein B) and lower HDL (cholesterol and unesterified cholesterol) were associated with higher muscle area, higher IMAT area, and lower IMAT density. Several associations between lipoprotein subfractions and abdominal muscle area and IMAT area and density were strongest among the stabilization muscles, particularly the obliques, illustrating the importance of examining muscle groups separately. Future work is needed to determine whether the observed associations indicate a lipoprotein profile contributing to worse skeletal muscle with fat infiltration.

MRI Assessment of Degeneration of Multifidus and Erector Spinae Muscles in Patients with Chronic Low Back Pain

Background The aim of this study was to examine degeneration in the lumbar musculus multifidus (L.MF) and lumbar musculus erector spina (L.ES) muscles in patients with mechanical chronic low back pain, non-radiculopathy chronic low back pain with discopathy, and healthy individuals. The relationships with low back pain were examined by comparing the results according to gender, pain, and lumbar segments. Material and Method: Evaluation was made of 36 healthy control subjects (Group 1), 37 patients with mechanical low back pain (Group 2) and 41 non-radiculopathy, lumbar discopathy patients (Group 3). On axial magnetic resonance images at the L3-S1 level, asymmetry between the left and right sides was examined in respect of L.MF and L.ES surface cross-sectional areas (CSA), total surface cross-sectional area (TCSA = L.MF + L.ES), and fat infiltration. Results The mean CSA values showed a significant difference only in the right L.MF in the healthy control group (p = 0.011). No statistically significant difference was seen between the groups in the comparisons of TCSA, and a statistically significant difference was determined in respect of fat infiltration in the right and left L.MF and the left L.ES (p = 0.011, p = 0.001, p = 0.027, respectively). When the CSA and TCSA were examined according to gender within the groups, the values were found to be statistically significantly higher in males (p < 0.001). The CSA and TCSA values of the L.MF and L.ES showed a significant difference between segments (L3-L4, L4-L5, L5-S1) (p < 0.001). No asymmetry was observed between the left /right CSA and TCSA values of the groups. Fat infiltration showed a significant difference according to gender and segments (p < 0.001). Conclusion Fat infiltration in the L.MF muscle is related to mechanical low back pain and lumbar discopathy. That there was no difference between the groups in the CSA and TCSA values demonstrates the need for measurement of muscle atrophy associated with fat infiltration or functional cross-section area rather than CSA and TCSA.