Gender- and Age-Related Changes in Trunk Muscle Composition Using Chemical Shift Encoding-Based Water⁻Fat MRI

Impact of baseline adipose tissue characteristics on change in adipose tissue volume during a low calorie diet in people with obesity-results from the LION study

BACKGROUND/OBJECTIVES

Weight loss outcomes vary individually. Magnetic resonance imaging (MRI)-based evaluation of adipose tissue (AT) might help to identify AT characteristics that predict AT loss. This study aimed to assess the impact of an 8-week low-calorie diet (LCD) on different AT depots and to identify predictors of short-term AT loss using MRI in adults with obesity.

METHODS

Eighty-one adults with obesity (mean BMI 34.08 ± 2.75 kg/m², mean age 46.3 ± 10.97 years, 49 females) prospectively underwent baseline MRI (liver dome to femoral head) and anthropometric measurements (BMI, waist-to-hip-ratio, body fat), followed by a post-LCD-examination. Visceral and subcutaneous AT (VAT and SAT) volumes and AT fat fraction were extracted from the MRI data. Apparent lipid volumes based on MRI were calculated as approximation for the lipid contained in the AT. SAT and VAT volumes were subdivided into equidistant thirds along the craniocaudal axis and normalized by length of the segmentation. T-tests compared baseline and follow-up measurements and sex differences. Effect sizes on subdivided AT volumes were compared. Spearman Rank correlation explored associations between baseline parameters and AT loss. Multiple regression analysis identified baseline predictors for AT loss.

RESULTS

Following the LCD, participants exhibited significant weight loss (11.61 ± 3.07 kg, p < 0.01) and reductions in all MRI-based AT parameters (p < 0.01). Absolute SAT loss exceeded VAT loss, while relative apparent lipid loss was higher in VAT (both p < 0.01). The lower abdominopelvic third showed the most significant SAT and VAT reduction. The predictor of most AT and apparent lipid losses was the normalized baseline SAT volume in the lower abdominopelvic third, with smaller volumes favoring greater AT loss (p < 0.01 for SAT and VAT loss and SAT apparent lipid volume loss).

CONCLUSIONS

The LCD primarily reduces lower abdominopelvic SAT and VAT. Furthermore, lower abdominopelvic SAT volume was detected as a potential predictor for short-term AT loss in persons with obesity.

What patient parameters influence lumbar stiffness in patients with hip pathology?

Lumbar stiffness leads to greater hip dependence to achieve sagittal motion and increases instability after total hip arthroplasty (THA). We aimed to determine parameters that influence lumbar stiffness among patients with hip pathology. We hypothesized that modifiable (degenerative changes, spinal canal stenosis, facet orientation) and nonmodifiable factors (muscle condition) would be associated with lumbar spine stiffness. In this retrospective case-cohort study from a tertiary referral center, consecutive patients presenting at a hip specialist clinic underwent standing and deep-seated radiographic assessment to measure lumbar lordosis (∆LL) (stiffness: ∆LL < 20°), hip flexion (∆PFA: pelvic femoral angle), and degree of degenerative-disc-disease (DDD) (facet osteoarthritis, disc height, endplate proliferative changes). Of these, 65 patients were selected with previous lumbar spine magnetic resonance imaging, allowing to determine lumbar facet orientation, spinal canal stenosis (Schizas classification), and flexor- and extensor-muscle atrophy (Goutallier classification). Mean ∆LL was 45° (range: 11°-72°) and four patients (6%) exhibited spine stiffness. Patients with multilevel DDD (n = 22) had less ∆LL than those with no/single level (n = 43) DDD (34° [range: 11°-53°] vs. 51° [21°-72°]; p < 0.001). Number of DDD levels correlated strongly with ∆LL (ρ = -0.642; p < 0.001). Spinal stiffness was only seen in patients with ≥4 DDD levels. There was no correlation between ∆LL and facet orientation (p > 0.05). ∆LL correlated strongly with extensor atrophy at L3-L4 (ρ = -0.473), L4-L5 (ρ = -0.520), and L5-S1 (ρ = -0.473) and poorly with flexors at L4-L5 (ρ = -0.134) and L5-S1 (ρ = -0.227). Lumbar stiffness is dependent on modifiable (muscle atrophy) and nonmodifiable (extend of DDD) factors. This can guide nonoperative management of hip pathology, emphasizing the relevance of core muscle rehabilitation to improve posture and stiffness. Identification ≥4 DDD levels should alert surgeons of increased THA instability risk. Level of evidence: level IV, cohort series.

Hepatocellular carcinoma in patients with non-alcoholic fatty liver disease is associated with heterogeneous pattern of fat infiltration in skeletal muscles

OBJECTIVES

To evaluate the association between fat infiltration in skeletal muscles (myosteatosis) and hepatocellular carcinoma (HCC) in patients with non-alcoholic fatty liver disease (NAFLD).

METHODS

In a cross-sectional cohort of 72 histologically proven NAFLD patients (n = 38 with non-alcoholic steatohepatitis; NASH), among which 20 had HCC diagnosed on biopsy, we used proton density fat fraction (PDFF) at MRI to evaluate myosteatosis in skeletal muscles (mean fat fraction and first order radiomic-based pattern) at the third lumbar level, namely in erector spinae (ES), quadratus lumborum (QL), psoas, oblique, and rectus muscles.

RESULTS

PDFFES was 70% higher in patients with HCC when compared to those without HCC (9.6 ± 5.5% versus 5.7 ± 3.0%, respectively, p < 0.001). In multivariate logistic regression, PDFFES was a significant predictor of the presence of HCC (AUC = 0.72, 95% CI 0.57-0.86, p = 0.002) independently from age, sex, visceral fat area, and liver fibrosis stage (all p < 0.05). The relationship between PDFFES and HCC was exacerbated in patients with NASH (AUC = 0.79, 95% CI 0.63-0.86, p = 0.006). In patients with NASH, radiomics features of heterogeneity such as energy and entropy in any of the paraspinal muscles (i.e., ES, QL, or psoas) were independent predictors of HCC. EnergyES identified patients with HCC (n = 13) in the NASH population with AUC = 0.92 (95% CI 0.82-1.00, p < 0.001).

CONCLUSION

In patients with NAFLD, and more specifically in those with NASH, the degree and heterogeneity of myosteatosis is independently associated with HCC irrespective of liver fibrosis stage.

CLINICAL RELEVANCE STATEMENT

Our data suggest that myosteatosis could be used as a biomarker of HCC in the ever-expanding NAFLD population and pave the way for further investigation in longitudinal studies.

KEY POINTS

• HCC in patients with non-alcoholic fatty liver disease, and more specifically in those with non-alcoholic steatohepatitis, is independently associated with severe fatty infiltration (myosteatosis) of paravertebral skeletal muscles. • Association between myosteatosis and HCC is independent from liver fibrosis stage. • Histogram-based radiomics features of myosteatosis predicts the risk of HCC in patients with non-alcoholic steatohepatitis.

Gender similarities and differences in skeletal muscle and body composition: an MRI study of recreational cyclists

Objectives

This study aims to quantitatively evaluate whether there are muscle mass differences between male and female recreational cyclists and compare muscle quality and body composition in the pelvis region between two well-matched groups of fit and healthy male and female adults.

Methods

This cross-sectional study involved 45 female and 42 male recreational cyclists. The inclusion criteria for both groups were to have cycled more than 7000 km in the last year, have an absence of injuries and other health problems, have no contraindication to MRI, and be 30-65 years old. Our main outcome measures were fat fraction, as a measure of intramuscular fat (IMF) content, and volume of the gluteal muscles measured using Dixon MRI. The gluteal subcutaneous adipose tissue (SAT) volume was evaluated as a secondary measure.

Results

We found that there were no gender differences in the IMF content of gluteus maximus (GMAX, p=0.42), gluteus medius (GMED, p=0.69) and gluteus minimus (GMIN, p=0.06) muscles, despite women having more gluteal SAT (p<0.01). Men had larger gluteal muscles than women (p<0.01), but no differences were found when muscle volume was normalised by body weight (GMAX, p=0.54; GMED, p=0.14; GMIN, p=0.19).

Conclusions

Our study shows that despite the recognised hormonal differences between men and women, there is gender equivalence in the muscle mass and quality of the gluteal muscles when matched for exercise and body weight. This new MRI study provides key information to better understand gender similarities and differences in skeletal muscle and body composition.

MRI biomarker of muscle composition is associated with severity of pelvic organ prolapse

BACKGROUND

The pathophysiology of pelvic organ prolapse is largely unknown. We hypothesized that reduced muscle mass on magnetic resonance defecography (MRD) is associated with increased pelvic floor laxity. The aim of this study was to compare the psoas and puborectalis muscle mass composition and cross-sectional area among patients with or without pelvic laxity.

METHODS

An observational retrospective study was conducted on women > age 18 years old who had undergone MRD for pelvic floor complaints from January 2020 to December 2020 at Stanford Pelvic Health Center. Pelvic floor laxity, pelvic organ descent, and rectal prolapse were characterized by standard measurements on MRD and compared to the psoas (L4 level) and puborectalis muscle index (cross-sectional area adjusted by height) and relative fat fraction, quantified by utilizing a 2-point Dixon technique. Regression analysis was used to quantify the association between muscle characteristics and pelvic organ measurements.

RESULTS

The psoas fat fraction was significantly elevated in patients with abnormally increased resting and strain H and M lines (p < 0.05) and increased with rising grades of Oxford rectal prolapse (p = 0.0001), uterovaginal descent (p = 0.001) and bladder descent (p = 0.0005). In multivariate regression analysis, adjusted for age and body mass index, the psoas fat fraction (not muscle index) was an independent risk factor for abnormal strain H and M line; odds ratio (95% confidence interval) of 17.8 (2-155.4) and 18.5 (1.3-258.3) respectively, and rising Oxford grade of rectal prolapse 153.9 (4.4-5383) and bladder descent 12.4 (1.5-106). Puborectalis fat fraction was increased by rising grades of Oxford rectal prolapse (p = 0.0002).

CONCLUSIONS

Severity of pelvic organ prolapse appears to be associated with increasing psoas muscle fat fraction, a biomarker for reduced skeletal muscle mass. Future prospective research is needed to determine if sarcopenia may predict postsurgical outcomes after pelvic organ prolapse repair.

Association of Cervical and Lumbar Paraspinal Muscle Composition Using Texture Analysis of MR-Based Proton Density Fat Fraction Maps

In this study, the associations of cervical and lumbar paraspinal musculature based on a texture analysis of proton density fat fraction (PDFF) maps were investigated to identify gender- and anatomical location-specific structural patterns. Seventy-nine volunteers (25 men, 54 women) participated in the present study (mean age ± standard deviation: men: 43.7 ± 24.6 years; women: 37.1 ± 14.0 years). Using manual segmentations of the PDFF maps, texture analysis was performed and texture features were extracted. A significant difference in the mean PDFF between men and women was observed in the erector spinae muscle (p < 0.0001), whereas the mean PDFF did not significantly differ in the cervical musculature and the psoas muscle (p > 0.05 each). Among others, Variance(global) and Kurtosis(global) showed significantly higher values in men than in women in all included muscle groups (p < 0.001). Not only the mean PDFF values (p < 0.001) but also Variance(global) (p < 0.001), Energy (p < 0.001), Entropy (p = 0.01), Homogeneity (p < 0.001), and Correlation (p = 0.037) differed significantly between the three muscle compartments. The cervical and lumbar paraspinal musculature composition seems to be gender-specific and has anatomical location-specific structural patterns.

MRI-Determined Psoas Muscle Fat Infiltration Correlates with Severity of Weight Loss during Cancer Cachexia

PURPOSE

To evaluate the suitability of psoas and erector spinae muscle proton density fat fraction (PDFF) and fat volume as biomarkers for monitoring cachexia severity in an oncological cohort, and to evaluate regional variances in muscle parameters over time.

METHODS

In this prospective study, 58 oncological patients were examined by a 3 T MRI receiving between one and five scans. Muscle volume and PDFF were measured, segmentation masks were divided into proximal, middle and distal muscle section.

RESULTS

A regional variation of fat distribution in erector spinae muscle at baseline was found (p < 0.01). During follow-ups significant relative change of muscle parameters was observed. Relative maximum change of erector spinae muscle showed a significant regional variation. Correlation testing with age as a covariate revealed significant correlations for baseline psoas fat volume (r = -0.55, p < 0.01) and baseline psoas PDFF (r = -0.52, p = 0.02) with maximum BMI change during the course of the disease.

CONCLUSION

In erector spinae muscles, a regional variation of fat distribution at baseline and relative maximum change of muscle parameters was observed. Our results indicate that psoas muscle PDFF and fat volume could serve as MRI-determined biomarkers for early risk stratification and disease monitoring regarding progression and severity of weight loss in cancer cachexia.

Low-dose MDCT: evaluation of the impact of systematic tube current reduction and sparse sampling on quantitative paraspinal muscle assessment

Background

Wasting disease entities like cachexia or sarcopenia are associated with a decreasing muscle mass and changing muscle composition. For valid and reliable disease detection and monitoring diagnostic techniques offering quantitative musculature assessment are needed. Multi-detector computed tomography (MDCT) is a broadly available imaging modality allowing for muscle composition analysis. A major disadvantage of using MDCT for muscle composition assessment is the radiation exposure. In this study we evaluated the performance of different methods of radiation dose reduction for paravertebral muscle composition assessment.

Methods

MDCT scans of eighteen subjects (6 males, age: 71.5±15.9 years, and 12 females, age: 71.0±8.9 years) were retrospectively simulated as if they were acquired at 50%, 10%, 5%, and 3% of the original X-ray tube current or number of projections (i.e., sparse sampling). Images were reconstructed with a statistical iterative reconstruction (SIR) algorithm. Paraspinal muscles (psoas and erector spinae muscles) at the level of L4 were segmented in the original-dose images. Segmentations were superimposed on all low-dose scans and muscle density (MD) extracted.

Results

Sparse sampling derived mean MD showed no significant changes (P=0.57 and P=0.22) down to 5% of the original projections in the erector spinae and psoas muscles, respectively. All virtually reduced tube current series showed significantly different (P>0.05) mean MD in the psoas and erector spinae muscles as compared to the original dose except for the images of 5% of the original tube current in the erector spinae muscle.

Conclusions

Our findings demonstrated the possibility of considerable radiation dose reduction using MDCT scans for assessing the composition of the paravertebral musculature. The sparse sampling approach seems to be promising and a potentially superior technique for dose reduction as compared to tube current reduction.

Regional variation of thigh muscle fat infiltration in patients with neuromuscular diseases compared to healthy controls

Background

Chemical shift encoding-based water-fat magnetic resonance imaging (CSE-MRI) measures a quantitative biomarker: the proton density fat fraction (PDFF). The aim was to assess regional and proximo-distal PDFF variations at the thigh in patients with myotonic dystrophy type 2 (DM2), limb-girdle muscular dystrophy type 2A (LGMD2A), and late-onset Pompe disease (LOPD) as compared to healthy controls.

Methods

Seven patients (n=2 DM2, n=2 LGMD2A, n=3 LOPD) and 20 controls were recruited. A 3D-spoiled gradient echo sequence was used to scan the thigh musculature. Muscles were manually segmented to generate mean muscle PDFF.

Results

In all three disease entities, there was an increase in muscle fat replacement compared to healthy controls. However, within each disease group, there were patients with a shorter time since symptom onset that only showed mild PDFF elevation (range, 10% to 20%) compared to controls (P≤0.05), whereas patients with a longer period since symptom onset showed a more severe grade of fat replacement with a range of 50% to 70% (P<0.01). Increased PDFF of around 5% was observed for vastus medialis, semimembranosus and gracilis muscles in advanced compared to early DM2. LGMD2A_1 showed an early disease stage with predominantly mild PDFF elevations over all muscles and levels (10.9%±7.1%) compared to controls. The quadriceps, gracilis and biceps femoris muscles showed the highest difference between LGMD2A_1 with 5 years since symptom onset (average PDFF 11.1%±6.9%) compared to LGMD2A_2 with 32 years since symptom onset (average PDFF 66.3%±6.3%). For LOPD patients, overall PDFF elevations were observed in all major hip flexors and extensors (range, 25.8% to 30.8%) compared to controls (range, 1.7% to 2.3%, P<0.05). Proximal-to-distal PDFF highly varied within and between diseases and within controls. The intra-reader reliability was high (reproducibility coefficient ≤2.19%).

Conclusions

By quantitatively measuring muscle fat infiltration at the thigh, we identified candidate muscles for disease monitoring due to their gradual PDFF elevation with longer disease duration. Regional variation between proximal, central, and distal muscle PDFF was high and is important to consider when performing longitudinal MRI follow-ups in the clinical setting or in longitudinal studies.

MRI and muscle imaging for idiopathic inflammatory myopathies

Although idiopathic inflammatory myopathies (IIM) are a heterogeneous group of diseases nearly all patients display muscle inflammation. Originally, muscle biopsy was considered as the gold standard for IIM diagnosis. The development of muscle imaging led to revisiting not only the IIM diagnosis strategy but also the patients' follow-up. Different techniques have been tested or are in development for IIM including positron emission tomography, ultrasound imaging, ultrasound shear wave elastography, though magnetic resonance imaging (MRI) remains the most widely used technique in routine. Whereas guidelines on muscle imaging in myositis are lacking here we reviewed the relevance of muscle imaging for both diagnosis and myositis patients' follow-up. We propose recommendations about when and how to perform MRI on myositis patients, and we describe new techniques that are under development.

Imaging Evaluation of Fat Infiltration in Paraspinal Muscles on MRI: A Systematic Review with a Focus on Methodology

Purpose

Numerous studies have applied a variety of methods to assess paraspinal muscle degeneration. However, the methodological differences in imaging evaluation may lead to imprecise or inconsistent results. This article aimed to provide a pragmatic summary review of the current imaging modalities, measurement protocols, and imaging parameters in the evaluation of paraspinal muscle fat infiltration (FI) in MRI studies.

Methods

Web of Science, EMBASE, and PubMed were searched from January 2005 to March 2020 to identify studies that examined the FI of paraspinal muscles on MRI among patients with lumbar degenerative diseases.

Results

Intramyocellular lipids measured by magnetic resonance spectroscopy and FI measured by chemical‐shift MRI were both correlated to low back pain and several degenerative lumbar diseases, whereas results on the relationship between FI and degenerative lumbar pathologies using conventional MRI were conflicting. Multi‐segment measurement of FI at the lesion segment and adjacent segments could be a prognostic indicator for lumbar surgery. Most studies adopted the center of the intervertebral disc or endplate as the level of slice to evaluate the FI. Compared with visual semiquantitative assessment, quantitative parameters appeared to be precise for eliminating individual or modality differences. It has been demonstrated that fat CSA/total CSA (based on area) and muscle–fat index (based on signal intensity) as quantitative FI parameters are associated with multiple lumbar diseases and clinical outcomes after surgery.

Conclusion

Having a good command of the methodology of paraspinal muscle FI on MRI was effective for diagnosis and prognosis in clinical practice.

Assessment of isokinetic trunk muscle strength and its association with health-related quality of life in patients with degenerative spinal deformity

Background

A considerable portion of the elderly population are increasingly afflicted by degenerative spinal deformity (DSD), which seriously affects patient health-related quality of life (HRQoL). HRQoL index is used across many studies to show correlations between radio-graphical alignment, disability, and pain in patients with DSD. However, imaged structural deformity represents only one aspect for consideration, namely, the disability effect of DSD. We assessed the isokinetic strength of trunk muscle in patients with degenerative spinal deformity (DSD), and investigated its relationship with HRQoL.

Methods

In total, 38 patients with DSD (DSD group) and 32 healthy individuals (control group) were recruited. Both groups were homogeneous for age, weight, height and body mass index (BMI). Assessments were performed using the isokinetic dynamometer IsoMed-2000; trunk extensor, flexor strength and flexion/extension (F/E) ratios were explored concentrically at speeds of 30°, 60° and 120° per second. The grip strength of both hands was measured using a hand-held dynamometer. Visual analogue scale (VAS) scores, the Oswestry Disability Index (ODI), a Roland-Morris disability questionnaire (RDQ), and a 36-item Short Form Health Survey (SF-36) evaluated patient HRQoL. Correlations between trunk strength and HRQoL were analyzed.

Results

When compared with the control group, the DSD group showed lower trunk extensor strength at three velocity movements, and higher F/E ratios at 60° and 120°/s (p < 0.05). Both groups exhibited similar trunk flexor strength and grip strength (p > 0.05). In DSD group, trunk extensor strength at 60°/s was negatively associated with ODI and RDQ (p < 0.05). A negative relationship between trunk flexor strength at 120°/s and ODI was also recorded (p < 0.05). In addition, trunk extensor strength at 60°/s and trunk flexor strength at 120°/s were positively correlated with physical functioning and role-physical scores according to the SF-36 (p < 0.05).

Conclusions

We identified isolated trunk extensor myopathy in DSD, which causes an imbalance in trunk muscle strength. Isokinetic trunk extensor strength at 60°/s and trunk flexor strength at 120°/s can predict disability, and decrease physical HRQoL in DSD patients.

Whole-body muscle MRI of patients with MATR3-associated distal myopathy reveals a distinct pattern of muscular involvement and highlights the value of whole-body examination

OBJECTIVE

MATR3-associated distal myopathy is a rare distal myopathy predominantly affecting lower legs as well as wrist- and finger extensors. Whilst most distal myopathies are clinically and genetically well characterized, diagnosis often remains challenging. Pattern-based magnetic resonance imaging (MRI) approaches offer valuable additional information. However, a consistent pattern of muscular affection is missing for most distal myopathies. Thus, the aim of the present study was to establish a disease-specific pattern of muscular involvement in MATR3-associated distal myopathy using whole-body MRI.

METHODS

15 patients (25-79 years of age, 7 female) with MATR3-associated distal myopathy were subjected to whole-body MRI. The grade of fatty involution for individual muscles was determined using Fischer-Grading. Results were compared to established MRI-patterns of other distal myopathies.

RESULTS

There was a predominant affection of the distal lower extremities. Lower legs showed a severe fatty infiltration, prominently affecting gastrocnemius and soleus muscle. In thighs, a preferential involvement of semimembranous and biceps femoris muscle was observed. Severe affection of gluteus minimus muscle as well as axial musculature, mainly affecting the thoracic segments, was seen. A sufficient discrimination to other forms of distal myopathy based solely on MRI-findings of the lower extremities was not possible. However, the inclusion of additional body parts seemed to yield specificity.

INTERPRETATION

Muscle MRI of patients with MATR3-associated distal myopathy revealed a distinct pattern of muscular involvement. The usage of whole-body muscle MRI provided valuable additional findings as compared to regular MRI of the lower extremities to improve distinction from other disease entities.

Regional variation in paraspinal muscle composition using chemical shift encoding-based water-fat MRI

Background

Paraspinal musculature forms one of the largest muscle compartments of the human body, but evidence for regional variation of its composition and dependency on gender or body mass index (BMI) is scarce.

Methods

This study applied six-echo chemical shift encoding-based water-fat magnetic resonance imaging (MRI) at 3 Tesla in 76 subjects (24 males and 52 females, age: 40.0±13.7 years, BMI: 25.4±5.6 kg/m²) to evaluate the proton density fat fraction (PDFF) of psoas muscles and erector spinae muscles, with the latter being divided into three segments in relation to levels of spine anatomy (L3-L5, T12-L2, and T9-T11).

Results

For the psoas muscles and the erector spinae muscles (L3-L5), gender differences in PDFF values were observed (PDFF psoas muscles: males: 5.1%±3.4% vs. females: 6.0%±2.2%, P=0.006; PDFF erector spinae muscles L3-L5: males: 10.7%±7.6% vs. females: 18.2%±6.8%, P<0.001). Furthermore, the PDFF of the erector spinae muscles (L3-L5) showed higher PDFF values when compared to the other segments (PDFF erector spinae muscles L3-L5 vs. T12-L2: P<0.001; PDFF erector spinae muscles L3-L5 vs. T9-T11: P<0.001) and showed to be independent of BMI, which was not the case for the other segments (T12-L2 or T9-T11) or the psoas muscles. When considering age and BMI as control variables, correlations of PDFF between segments of the erector spinae muscles remained significant for both genders.

Conclusions

This study explored regional variation of paraspinal muscle composition and dependency on gender and BMI, thus offering new insights into muscle physiology. The PDFF of the erector spinae muscles (L3-L5) was independent of BMI, suggesting that this level may be suited for representative paraspinal muscle segmentation and PDFF extraction as a biomarker for muscle alterations in the future.

Assessment of paraspinal muscle characteristics, lumbar BMD, and their associations in routine multi-detector CT of patients with and without osteoporotic vertebral fractures

PURPOSE

To investigate paraspinal muscle characteristics and lumbar bone mineral density (BMD) and their associations in routine abdominal multi-detector computed tomography (MDCT) as well as the impact of osteoporotic vertebral fractures on such associations.

METHOD

116 patients (69.7 ± 8.1 years, 72 males) who underwent routine abdominal MDCT (oncological staging and/or follow-up for tumor recurrence) were retrospectively included and assigned to a fracture and control group (age- and gender-matched), depending on the presence or absence of lumbar osteoporotic vertebral fractures. BMD was derived from lumbar vertebrae using a conversion equation, and the cross-sectional area (CSA), CSA ratio (CSA psoas muscles divided by CSA erector spinae muscles), and muscle attenuation were measured for the psoas and erector spinae muscles at the levels L2 and L4/5 without dedicated software.

RESULTS

Males showed significantly higher BMD, CSA, and CSA ratios at the levels L2 and L4/5, while females had decreased erector spinae muscle attenuation at L4/5 (p < 0.05). No significant differences between patients with versus without fractures were observed except for BMD (68.5 ± 37.2 mg/ml vs. 91.4 ± 26.8 mg/ml; p < 0.01). Age-adjusted partial correlation testing revealed significant correlations of BMD and the CSA ratio at level L4/5 (r = 0.20; p = 0.03), but not with muscle attenuation (p > 0.05).

CONCLUSIONS

Paraspinal muscle characteristics and lumbar BMD can be assessed seamlessly in routine abdominal MDCT without dedicated software. There are level-dependent interactions between paraspinal muscle characteristics as well as lumbar BMD. Vertebral fracture status was independent of paraspinal muscle characteristics.

Age- and gender-related variations of cervical muscle composition using chemical shift encoding-based water-fat MRI

PURPOSE

To understand fat distribution patterns and ectopic fat deposition in healthy adults and to provide normative data, encompassing the borders of physiological regional muscle composition. For this purpose chemical shift encoding-based water-fat Magnetic Resonance Imaging (MRI) was used for proton density fat fraction (PDFF) calculations.

MATERIAL AND METHODS

91 volunteers were enrolled (male: n = 28, age = 36.6 ± 11.4 years; female: n = 63, age = 38.5 ± 15.1 years). PDFF values combined for the multifidus, semispinalis and spinalis cervicis muscles at the level of the 3rd cervical vertebral body (C3), the 5th cervical vertebral body (C5) and the first thoracic vertebral body (Th1) were extracted.

RESULTS

The paraspinal musculature at C3 (14.8 ± 10.1 % vs. 19.2 ± 11.0 %; p = 0.029) and Th1 (13.8 ± 7.0 % vs 17.7 ± 7.4 %; p = 0.011) showed significantly lower PDFF values in men compared to women. Partial correlation testing with BMI as control variable revealed highly significant correlations between the paraspinal musculature PDFF at C3 (men: r = 0.504, p = 0.007; women: r = 0.279, p = 0.028), C5 (men: r = 0.450, p = 0.019; women: r = 0.347, p = 0.006) and Th1 (men: r = 0.652, p < 0.0001; women: r = 0.443, p < 0.0001) with age in both genders.

CONCLUSION

The present data suggest gender and age-specific fat deposition patterns of the cervical and the upper cervicothoracic paraspinal muscles and may provide reference values for pathology detection.

Age-related degeneration of the lumbar paravertebral muscles: Systematic review and three-level meta-regression

BACKGROUND

Morphological changes of the lumbar spine muscles are not well characterised with ageing. To further the understanding of age-related degeneration of the lumbar spine musculature, normative morphological changes that occur within the paravertebral muscles must first be established.

METHODS

A systematic review and meta-regressions were conducted adhering to PRISMA guidelines. Searches for published and unpublished data were completed in June 2019.

RESULTS

Searches returned 4781 articles. 34 articles were included in the quantitative analysis. Three-level meta-analyses showed age-related atrophy (r = -0.26; 95% CI: -0.33, -0.17) and fat infiltration (r = 0.39; 95% CI: 0.28, 0.50) in the lumbar paravertebral muscles. Degenerative changes were muscle-specific and men (r = -0.32; 95% CI: -0.61, 0.01) exhibited significantly greater muscle atrophy than women (r = -0.24; 95% CI: -0.47, 0.03). Imaging modality, specifically ultrasound, also influenced age-related muscle atrophy. Measurements taken across all lumbar levels revealed the greatest fat infiltration with ageing (r = 0.58, 95% CI: 0.35, 0.74). Moderators explained a large proportion of between-study variance in true effects for muscle atrophy (72.6%) and fat infiltration (79.8%) models.

CONCLUSIONS

Lumbar paravertebral muscles undergo age-related degeneration in healthy adults with muscle, lumbar level and sex-specific responses. Future studies should use high-resolution imaging modalities to quantify muscle atrophy and fat infiltration.

Association of thigh and paraspinal muscle composition in young adults using chemical shift encoding-based water-fat MRI

Background

Paraspinal and thigh muscles comprise the major muscle groups of the body. We investigated the composition of the psoas, erector spinae, quadriceps femoris and hamstring muscle groups and their association to each other using chemical shift encoding-based water-fat magnetic resonance imaging (MRI) in adult volunteers. Our aim was to elucidate fat distribution patterns within these muscle groups.

Methods

Thirty volunteers [15 males, age: 30.5±4.9 years, body mass index (BMI): 27.6±2.8 kg/m² and 15 females, age: 29.9±7.0 years, BMI: 25.8±1.4 kg/m²] were recruited for this study. A six-echo 3D spoiled gradient echo sequence was used for chemical shift encoding-based water-fat separation at the lumbar spine and bilateral thigh. Proton density fat fraction (PDFF), cross-sectional area (CSA) and contractile mass index (CMI) of the psoas, erector spinae, quadriceps femoris and hamstring muscle groups were determined bilaterally and averaged over both sides.

Results

CSA and CMI values calculated for the erector spinae, psoas, quadriceps and hamstring muscle groups showed significant differences between men and women (P<0.05). With regard to PDFF measurement only the erector spinae showed significant differences between men and women (9.5%±2.4% vs. 11.7%±2.8%, P=0.015). The CMI of the psoas muscle as well as the erector spinae muscle showed significant correlations with the quadriceps muscle (r=0.691, P<0.0001 and r=0.761, P<0.0001) and the hamstring group (r=0.588, P=0.001 and r=0.603, P<0.0001).

Conclusions

CMI values of the erector spinae and psoas muscles were associated with those of the quadriceps femoris and hamstring musculature. These findings suggest a concordant spatial fat accumulation within the analyzed muscles in young adults and warrants further investigations in ageing and diseased muscle.

Imaging of sarcopenia: old evidence and new insights

To date, sarcopenia is considered a patient-specific imaging biomarker able to predict clinical outcomes. Several imaging modalities, including dual-energy X-ray absorptiometry (DXA), computed tomography (CT), magnetic resonance (MR), and ultrasound (US), can be used to assess muscle mass and quality and to achieve the diagnosis of sarcopenia. With different extent, all these modalities can provide quantitative data, being thus reproducible and comparable over time. DXA is the one most commonly used in clinical practice, with the advantages of being accurate and widely available, and also being the only radiological tool with accepted cutoff values to diagnose sarcopenia. CT and MR are considered the reference standards, allowing the evaluation of muscle quality and fatty infiltration, but their application is so far mostly limited to research. US has been always regarded as a minor tool in sarcopenia and has never gained enough space. To date, CT is probably the easiest and most promising modality, although limited by the long time needed for muscle segmentation. Also, the absence of validated thresholds for CT measurements of myosteatosis requires that future studies should focus on this point. Radiologists have the great potential of becoming pivotal in the context of sarcopenia. We highly master imaging modalities and know perfectly how to apply them to different organs and clinical scenarios. Similarly, radiologists should master the culture of sarcopenia, and its clinical aspects and relevant implications for patient care. The medical and scientific radiological community should promote specific educational course to spread awareness among professionals. KEY POINTS: • DXA is an accurate, reproducible, and widely available imaging modality to evaluate body composition, being the most commonly used radiological tool to diagnose sarcopenia in clinical practice • CT and MR are the gold standard imaging modalities to assess muscle mass and quality, but no clear cutoff values have been reported to identify sarcopenia, limiting the application of these modalities to research purposes • US has shown to be accurate in the evaluation of muscle trophism, especially in the thigh, but its current application in sarcopenia is limited.

MRI-Derived Biomarkers Related to Sarcopenia: A Systematic Review

BACKGROUND

MRI allows quantitatively assessing muscle quantity and quality.

PURPOSE

To summarize the role of MRI as a noninvasive technique for the identification of in vivo surrogate biomarker of sarcopenia.

STUDY TYPE

Systematic review.

POPULATION

In April 2019, a systematic literature search (Medline/EMBASE) was performed to identify articles on the topic at issue.

FIELD STRENGTH/SEQUENCE

No field strength or sequence restrictions.

ASSESSMENT

After a literature search, study design, aim, sample size, demographics, magnetic field strength, imaged body region, MRI sequences, and imaging biomarker were extracted.

STATISTICAL TESTS

Data are presented as frequencies and percentages.

RESULTS

From 69 records identified through search query, 18 articles matched the inclusion criteria. All articles were published from 2012 and had a mainly prospective design (14/18, 78%). Sample size ranged from 9 to 284 subjects, for a total of 1706 enrolled subjects. Healthy subjects were enrolled or retrospectively selected in 8/18 (44%) articles, corresponding to 658 (39%) healthy subjects. Magnetic field strength was 1.5 or 3T in 14/18 (78%) studies. The most analyzed body regions were the thigh (7/18, 39%) and the trunk (6/18, 33%). Stratifying studies according to their aim, 13/18 (72%) studies focused on muscle quality and quantity, 3/18 (17%) studies on outcome prediction, and 2/18 articles (11%) addressed both aims. A wide set of MRI biomarkers have been proposed. Muscle cross-sectional area was the most used for muscle quantity estimation, while quantitative biomarkers of muscle fat content or fiber architecture were proposed to assess muscle quality.

DATA CONCLUSION

The proposed biomarkers were assessed using different MRI sequences for different body regions in different subjects/patient cohorts, pointing out a lack of standardization on this topic. Future studies should test and compare the performance of proposed MRI biomarkers for sarcopenia characterization and quantification using a standardized experimental setup.

LEVEL OF EVIDENCE

1 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2020;51:1117-1127.