Quantitative ultrasound image analysis of the supraspinatus muscle

Skeletal Muscle Assessment Using Quantitative Ultrasound: A Narrative Review

Ultrasound (US) is an important imaging tool for skeletal muscle analysis. The advantages of US include point-of-care access, real-time imaging, cost-effectiveness, and absence of ionizing radiation. However, US can be highly dependent on the operator and/or US system, and a portion of the potentially useful information carried by raw sonographic data is discarded in image formation for routine qualitative US. Quantitative ultrasound (QUS) methods provide analysis of the raw or post-processed data, revealing additional information about normal tissue structure and disease status. There are four QUS categories that can be used on muscle and are important to review. First, quantitative data derived from B-mode images can help determine the macrostructural anatomy and microstructural morphology of muscle tissues. Second, US elastography can provide information about muscle elasticity or stiffness through strain elastography or shear wave elastography (SWE). Strain elastography measures the induced tissue strain caused either by internal or external compression by tracking tissue displacement with detectable speckle in B-mode images of the examined tissue. SWE measures the speed of induced shear waves traveling through the tissue to estimate the tissue elasticity. These shear waves may be produced using external mechanical vibrations or internal "push pulse" ultrasound stimuli. Third, raw radiofrequency signal analyses provide estimates of fundamental tissue parameters, such as the speed of sound, attenuation coefficient, and backscatter coefficient, which correspond to information about muscle tissue microstructure and composition. Lastly, envelope statistical analyses apply various probability distributions to estimate the number density of scatterers and quantify coherent to incoherent signals, thus providing information about microstructural properties of muscle tissue. This review will examine these QUS techniques, published results on QUS evaluation of skeletal muscles, and the strengths and limitations of QUS in skeletal muscle analysis.

Comparison of Quantitative Ultrasound Methods to Classify Dystrophic and Obese Models of Skeletal Muscle

In this study, we compared multiple quantitative ultrasound metrics for the purpose of differentiating muscle in 20 healthy, 10 dystrophic and 10 obese mice. High-frequency ultrasound scans were acquired on dystrophic (D2-mdx), obese (db/db) and control mouse hindlimbs. A total of 248 image features were extracted from each scan, using brightness-mode statistics, Canny edge detection metrics, Haralick features, envelope statistics and radiofrequency statistics. Naïve Bayes and other classifiers were trained on single and pairs of features. The a parameter from the Homodyned K distribution at 40 MHz achieved the best univariate classification (accuracy = 85.3%). Maximum classification accuracy of 97.7% was achieved using a logistic regression classifier on the feature pair of a² (K distribution) at 30 MHz and brightness-mode variance at 40MHz. Dystrophic and obese mice have muscle with distinct acoustic properties and can be classified to a high level of accuracy using a combination of multiple features.

The Application of Image Texture Analysis Techniques on the Effects of Dry Needling versus Placebo in Low-Back Pain Patients: A Pilot-Study

Low back pain is the leading cause of disability in the world, with a significant socio-economic impact. Deep dry needling is effective in the treatment of this pain, and it is one of the techniques preferred by physiotherapists. In this field, the use of ultrasound provides information of interest such as length, thickness, diameter, cross-sectional area, or muscle volume, among others. Objective: To find out whether the tissue changes (thickness, histogram, and contraction rate) that occur in the lumbar multifidus after application of the deep dry needle are related to changes in the pain and the disability of the patient. Design: Randomized, double-blind, parallel-group clinical trial. Setting: University of Alcalá, Department of Physiotherapy. Subjects: 21 voluntary patients (women and men) with non-specific low-back pain aged 18–65 years. Intervention: Patients were randomly divided into two groups. One group received dry needling and the other group a dry needling placebo. Initial post-needling and one week post-needling assessments were performed by a therapist blinded to the intervention. Variables: Lumbar multifidus thickness measured by RUSI, contraction time measured by M-mode, histograms measured by image analysis, muscle area, pain measured by VAS, pressure pain threshold measured by pressure algometer, and disability measured by Roland–Morris questionnaire. Conclusions: The contraction speed, resting thickness, and pain demonstrated significant differences within each group, but not between groups. There were significant differences in contraction ratio and in PPT between groups. There was excellent intra-examiner reliability in image collection for histogram analysis. Histogram analysis showed no significant differences between groups and measurements, neither for the parameters nor for the parameters combined with the outcome variables. A robust method for the image texture analyses in future histogram muscle analyses has been performed.

Noninvasive Detection, Tracking, and Characterization of Aerogel Implants Using Diagnostic Ultrasound

Medical implants are routinely tracked and monitored using different techniques, such as MRI, X-ray, and ultrasound. Due to the need for ionizing radiation, the two former methods pose a significant risk to tissue. Ultrasound imaging, however, is non-invasive and presents no known risk to human tissue. Aerogels are an emerging material with great potential in biomedical implants. While qualitative observation of ultrasound images by experts can already provide a lot of information about the implants and the surrounding structures, this paper describes the development and study of two simple B-Mode image analysis techniques based on attenuation measurements and echogenicity comparisons, which can further enhance the study of the biological tissues and implants, especially of different types of biocompatible aerogels.

Ultrasound use in metastatic breast cancer to measure body composition changes following an exercise intervention

Changes in body composition and muscle dysfunction are common in metastatic breast cancer (MBC). Ultrasound imaging (US) offers reliable information about muscle and fat tissue architecture (thickness) and quality (echo-intensity). This study aimed to analyze the responsiveness of thickness and echo-intensity and its possible relationship with functional and patient reported-outcomes (PRO) in MBC patients after an exercise intervention. A prospective study was conducted in 2019. A 12-week exercise program was performed, including aerobic exercise and strength training. Measurements were made at baseline and after intervention. Thickness and echo-intensity were obtained from the quadriceps and biceps brachii and brachialis (BB). Mean differences were calculated using the T-Student parametric test for dependent samples of the differences in the means before and after the intervention (p = 0.05; 95% CI). Data from 13 MBC patients showed that some US muscle variables had significant differences after intervention. Best correlations were found between the quality of life questionnaire (QLQ-BR23) PRO and variables from BB muscle thickness in contraction (r = 0.61, p < 0.01), and Non-contraction (r = 0.55, p < 0.01). BB Muscle Non-contraction Thickness also explained 70% of QLQ-BR23 variance. In conclusion, muscle architecture biomarkers showed great responsiveness and are correlated with PRO after an exercise intervention in MBC patients.

Quantitative ultrasound of trapezius muscle involvement in myofascial pain: comparison of clinical and healthy population using texture analysis

PURPOSE

Ultrasound is a non-invasive quantitative method to characterize sonographic textures of skeletal muscles. To date, there is no information available on the trapezius muscle. This study assessed the trapezius muscles of patients with myofascial pain compared with normal healthy participants.

METHODS

The trapezius muscles of 15 healthy and 17 myofascial pain participants were assessed using B-mode ultrasound to obtain 120 images for healthy and 162 images from myofascial pain participants. Texture features such as blob area, count and local binary patterns (LBP) were calculated. Multi-feature classification and analysis were performed using principal component analysis (PCA) and MANOVA to determine whether there were statistical differences.

RESULTS

We demonstrate the two principal components composed of a combination of LBP and blob parameters which explain 92.55% of the cumulative variance of our data set. In addition, blob characteristics were significantly different between healthy and myofascial pain participants.

CONCLUSION

Our study provides evidence that texture analysis techniques can differentiate between healthy and myofascial pain affected trapezius muscles. Further research is necessary to evaluate the nature of these differences.

The effect of trunk stabilization circuit exercise using a rubber mat on the thickness and white area index of transverse abdominis in healthy young adults

[Purpose] The purpose of this study was to investigate the effect of trunk stabilization circuit exercise using a rubber mat on the thickness and white area index of the transverse abdominis in college students in their 20’s. [Subjects and Methods] The subjects were randomly assigned to the experimental group and the control group. Those exercises were provided to twenty eight healthy adults in their 20s for four weeks and the thickness of transverse abdominis was measured before study and after 4 weeks. [Results] There were significant differences in interaction between two groups. Paired t-test for thickness and white area index of transverse abdominis showed statistically significant differences to experimentals than controls. Independent t-test for white area index of transverse abdominis also showed statistically significant differences to experimentals than controls. [Conclusion] In conclusion, there was statistically significant difference between the effects of trunk stabilization circuit exercises on back muscles according to types of the surface, and it is expected that this result will be used as a basic data in studies of abdominal muscle stabilization in the future.

Quantitative 3-D Ultrasound of the Medial Gastrocnemius Muscle in Children with Unilateral Spastic Cerebral Palsy

Three-dimensional ultrasound (3-DUS) was used to examine the size and appearance of the medial gastrocnemius (MG) muscle in children with unilateral cerebral palsy (CP). Twenty-six children with CP and 10 typically developing (TD) children participated. Three-dimensional US images of both limbs in children with CP and the right limb in TD children were analysed using quantitative methods to determine muscle volume, global echo intensity, global echo pattern and regional echo intensity. Significant differences in MG volume and all echo parameters were found between TD and CP children. The more involved limb was smaller and had higher echo intensity and a more heterogenous echo pattern compared with the TD group. Compared with that of the more involved limb, the MG of the less involved limb was larger but had a similar echo appearance. The MG of both limbs in children with unilateral spastic CP is smaller and, based on quantitative ultrasound, structurally different from that of TD children.

Quantitative ultrasound imaging of Achilles tendon integrity in symptomatic and asymptomatic individuals: reliability and minimal detectable change

Background

Quantifying the integrity of the Achilles tendon (AT) is a rehabilitation challenge. Adopting quantitative ultrasound measurements (QUS measurements) of the AT could fill this gap by 1) evaluating the test-retest reliability and accuracy of QUS measurements of the AT; 2) determining the best protocol for collecting QUS measurements in clinical practice.

Methods

A total of 23 ATs with symptoms of Achilles tendinopathy and 63 asymptomatic ATs were evaluated. Eight images were recorded for each AT (2 visits × 2 evaluators × 2 images). Multiple sets of QUS measurements were taken: geometric (thickness, width, area), first-order statistics (computed from a grayscale histogram distribution: echogenicity, variance, skewness, kurtosis, entropy) and texture features (computed from co-occurrence matrices: contrast, energy, homogeneity). A generalizability study quantified the reliability and standard error of measurement (accuracy) of each QUS measurement, and a decision study identified the best measurement taking protocols.

Results

Geometric QUS measurements demonstrated excellent accuracy and reliability. QUS measurements computed from the grayscale histogram distribution revealed poor accuracy and reliability. QUS measurements derived from co-occurrence matrices showed variable accuracy and moderate to excellent reliability. In clinical practice, using an average of the results of three images collected by a single evaluator during a single visit is recommended.

Conclusions

The use of geometric QUS measurements enables quantification of AT integrity in clinical practice and research settings. More studies on QUS measurements derived from co-occurrence matrices are warranted.

Do ultrasound findings of levator ani "avulsion" correlate with anatomical findings: A multicenter cadaveric study

AIMS

This study aimed to validate the levator "avulsion" injury as seen on ultrasound against anatomical dissection in the same cadaver.

METHODS

Puboviseral muscle (PVM) anatomy of female cadavers was studied using 3D-translabial ultrasonography and an "avulsion" confirmed per standard recommendations [Dietz HP. Aust N Z J Obstet Gynaecol 53:220-230, 2013]. Cadavers were then dissected to determine the macroscopic attachment or detachment of the PVM and the dimensions including the PVM symphysis gap and PVM attachment depth. Intra and inter-observer reliability of USS findings and anatomical measurements were assessed using the Cohen's κ and Bland & Altman plots respectively. McNemar's and Mann-Whitney U tests were used to compare imaging and cadaveric dissection findings.

RESULTS

"Avulsions" were seen on imaging in 11/30 (36.7%) cadavers; the defect was bilateral in 1/30 (3.3%) and unilateral in 10/30 (33.3%). No "avulsion" was found at dissection (McNemar's χ(2)  = 60.0, P < 0.001). An additional thirty-nine cadavers were dissected with no "avulsion" identified. A narrower PVM insertion depth was strongly associated with "avulsion" on ultrasound (mean: 4.79 mm vs. 6.32 mm, Z = -3.191, P = 0.001). Intra- and inter-observer agreement was perfect (K = 1.0 ± 0.0) and good (K = 0.85 ± 0.142) for anatomical "avulsions" and USS, respectively.

CONCLUSIONS

There is a clear difference between anatomical and USS findings. The imaged appearance of an "avulsion" does not represent a true anatomical "avulsion" as confirmed on dissection. The term "avulsion" is misrepresentative and should not be used to describe this imaging finding. Moreover, further attempts at surgically repairing this defect should be avoided, at least until there is a better understanding of its pathophysiology. Neurourol. Urodynam 35:683-688, 2016. © 2015 Wiley Periodicals, Inc.

Curvelet based automatic segmentation of supraspinatus tendon from ultrasound image: a focused assistive diagnostic method

Background

Disorders of rotator cuff tendons results in acute pain limiting the normal range of motion for shoulder. Of all the tendons in rotator cuff, supraspinatus (SSP) tendon is affected first of any pathological changes. Diagnosis of SSP tendon using ultrasound is considered to be operator dependent with its accuracy being related to operator’s level of experience.

Methods

The automatic segmentation of SSP tendon ultrasound image was performed to provide focused and more accurate diagnosis. The image processing techniques were employed for automatic segmentation of SSP tendon. The image processing techniques combines curvelet transform and mathematical concepts of logical and morphological operators along with area filtering. The segmentation assessment was performed using true positives rate, false positives rate and also accuracy of segmentation. The specificity and sensitivity of the algorithm was tested for diagnosis of partial thickness tears (PTTs) and full thickness tears (FTTs). The ultrasound images of SSP tendon were taken from medical center with the help of experienced radiologists. The algorithm was tested on 116 images taken from 51 different patients.

Results

The accuracy of segmentation of SSP tendon was calculated to be 95.61% in accordance with the segmentation performed by radiologists, with true positives rate of 91.37% and false positives rate of 8.62%. The specificity and sensitivity was found to be 93.6%, 94% and 95%, 95.6% for partial thickness tears and full thickness tears respectively. The proposed methodology was successfully tested over a database of more than 116 US images, for which radiologist assessment and validation was performed.

Conclusions

The segmentation of SSP tendon from ultrasound images helps in focused, accurate and more reliable diagnosis which has been verified with the help of two experienced radiologists. The specificity and sensitivity for accurate detection of partial and full thickness tears has been considerably increased after segmentation when compared with existing literature.

Quantitative evaluation of the echo intensity of the median nerve and flexor muscles of the forearm in the young and the elderly

OBJECTIVES

Musculoskeletal structures often appear brighter on imaging in the elderly, which makes it difficult to accurately delineate a peripheral nerve during ultrasound-guided regional anaesthetic procedures. The echo intensity of skeletal muscles is significantly increased in the elderly. However, there are no data comparing the echo intensity of peripheral nerves in the young and the elderly, which this study was designed to evaluate.

METHODS

13 healthy, young volunteers (aged <30 years) and 11 elderly patients (aged >60 years) who were scheduled to undergo orthopaedic lower limb surgery were recruited. The settings of the ultrasound system were standardised and a high-frequency linear array transducer was used for the scan. A transverse scan of the median nerve (MN) and the flexor muscles (FMs) at the left mid-forearm was performed and three video loops of the ultrasound scan were recorded for each subject. Still images were captured from the video loops and normalised. Computer-assisted greyscale analysis was then performed on these images to determine the echo intensity of the MN and the FMs of the forearm.

RESULTS

The echo intensity of the MN and FMs of the mid-forearm was significantly increased in the elderly (p<0.005). There was also a reduction in contrast between the MN and the adjoining FM in the elderly (p = 0.04).

CONCLUSION

Under the conditions of this study, the MN and the FMs in the forearm appeared significantly brighter than those in the young, and there was a loss of contrast between these structures in sonograms of the elderly.

Sonoanatomy relevant for ultrasound-guided central neuraxial blocks via the paramedian approach in the lumbar region

OBJECTIVES

The use of ultrasound to guide peripheral nerve blocks is now a well-established technique in regional anaesthesia. However, despite reports of ultrasound guided epidural access via the paramedian approach, there are limited data on the use of ultrasound for central neuraxial blocks, which may be due to a poor understanding of spinal sonoanatomy. The aim of this study was to define the sonoanatomy of the lumbar spine relevant for central neuraxial blocks via the paramedian approach.

METHODS

The sonoanatomy of the lumbar spine relevant for central neuraxial blocks via the paramedian approach was defined using a "water-based spine phantom", young volunteers and anatomical slices rendered from the Visible Human Project data set.

RESULTS

The water-based spine phantom was a simple model to study the sonoanatomy of the osseous elements of the lumbar spine. Each osseous element of the lumbar spine, in the spine phantom, produced a "signature pattern" on the paramedian sagittal scans, which was comparable to its sonographic appearance in vivo. In the volunteers, despite the narrow acoustic window, the ultrasound visibility of the neuraxial structures at the L3/L4 and L4/L5 lumbar intervertebral spaces was good, and we were able to delineate the sonoanatomy relevant for ultrasound-guided central neuraxial blocks via the paramedian approach.

CONCLUSION

Using a simple water-based spine phantom, volunteer scans and anatomical slices from the Visible Human Project (cadaver) we have described the sonoanatomy relevant for ultrasound-guided central neuraxial blocks via the paramedian approach in the lumbar region.

Reliability of quantitative ultrasound measures of the biceps and supraspinatus tendons

RATIONALE AND OBJECTIVES

Ultrasound is a proven method for examining soft tissue structures, including tendons, and recently quantitative ultrasound has become more prevalent in research settings. However, limited reliability data have been published for these new quantitative ultrasound measures. The main objective of this study was to quantify the reliability and measurement error of multiple quantitative ultrasound imaging protocols for the biceps and supraspinatus tendons.

MATERIALS AND METHODS

Two examiners captured ultrasound images of the non-dominant long head of the biceps tendon and supraspinatus tendon from 15 able-bodied participants and five manual wheelchair users. Each examiner captured two images per subject under two different preparations, which included subject positioning and reference marker placement. Image processing (reading) was performed twice to compute nine quantitative ultrasound measures of grayscale tendon appearance using first-order statistics and texture analysis. Generalizability theory was applied to compute interrater and intrarater reliability using the coefficient of dependability (Phi) for multiple study design protocols.

RESULTS

Interrater reliability was generally low (0.26 < Phi < 0.82), and it is recommended that a single evaluator capture all images for quantitative ultrasound protocols. Most of the quantitative ultrasound measures (n = 14 of 18) exhibited at least moderate (Phi > 0.50) intrarater reliability for a single image captured under one preparation and read once.

CONCLUSION

By following a protocol designed to minimize measurement error, one can increase the reliability of quantitative ultrasound measures. An appropriately designed protocol will allow quantitative ultrasound to be used as an outcome measure to identify structural changes within tendons.

Quantitative ultrasound tissue characterization in shoulder and thigh muscles--a new approach

BACKGROUND

The echogenicity patterns of ultrasound scans contain information of tissue composition in muscles. The aim was: (1) to develop a quantitative ultrasound image analysis to characterize tissue composition in terms of intensity and structure of the ultrasound images, and (2) to use the method for characterization of ultrasound images of the supraspinatus muscle, and the vastus lateralis muscle.

METHODS

Computerized texture analyses employing first-order and higher-order grey-scale statistics were developed to objectively characterize ultrasound images of m. supraspinatus and m. vastus lateralis from 9 healthy participants.

RESULTS

The mean grey-scale intensity was higher in the vastus lateralis muscle (p < 0.05) than in the supraspinatus muscle (average value of middle measuring site 51.4 compared to 35.0). Furthermore, the number of spatially connected and homogeneous regions (blobs) was higher in the vastus lateralis (p < 0.05) than in the supraspinatus (average for m. vastus lateralis: 0.092 mm(-2) and for m. supraspinatus: 0.016 mm(-2)).

CONCLUSION

The higher intensity and the higher number of blobs in the vastus lateralis muscle indicates that the thigh muscle contained more non-contractile components than the supraspinatus muscle, and that the muscle was coarser. The image analyses supplemented each other and gave a more complete description of the tissue composition in the muscle than the mean grey-scale value alone.

Dynamic ultrasonography of rotator cuff muscles

PURPOSE

To confirm the neuromuscular integrity of the rotator cuff and to investigate the effect of different contraction patterns on shoulder function, we sonographically analyzed dynamic contraction patterns of this muscle group.

METHODS

Fifty supra- and 50 infraspinatus muscle contraction patterns of patients with different shoulder pathologies examined with a 7.5-MHz transducer were recorded and saved as video files. Both data sets were analyzed by 3 independent observers who then assigned a grade to each contraction pattern: normal, slightly disturbed, severely disturbed, or no contraction. Intra- and inter-observer variations were calculated. In 43 patients with isolated supraspinatus tears, the clinical relation to shoulder function as measured with the Constant score was evaluated.

RESULTS

In the 100 cases tested, the intraclass correlations for the 3 observers were 0.82, 0.88, and 0.88. The inter-observer reliability was 0.74. No pair of first and second readings for either the supraspinatus or infraspinatus muscle differed by more than 1 grade. In patients with a supraspinatus tear, the contraction type of the supraspinatus correlated significantly with the Constant score (p=0.02).

CONCLUSIONS

When dynamic ultrasonography is used to assess the contraction patterns of the supra- and infraspinatus muscles, good intra- and inter-observer reliability is attained. Because a better contraction type correlates significantly with better shoulder function, this new diagnostic criterion may improve decision-making in the treatment of shoulder diseases.

Muscle ultrasound analysis: normal values and differentiation between myopathies and neuropathies

In this study, 145 healthy adults (20 to 94 years old, 69 women) were examined using ultrasound (US) imaging to obtain reference values of muscle parameters that were previously not available. We measured biceps and quadriceps sizes and subcutaneous fat thickness. To quantify muscle aspect, we defined and calculated the muscle aspect parameters muscle density, inhomogeneity and white-area index by digital image analysis. All muscle aspect parameters were found to increase with age, which may be due to age-related muscle replacement by fatty tissue and collagen. Other age-, weight- and gender-dependencies are also discussed. The complete set of muscle parameters was used to differentiate between typical myopathies and neuropathies in a group of 32 patients (24 to 79 years old, 18 women). We were successful in almost completely separating the two types of disorders based on abnormality of muscle aspect parameters alone. These preliminary results show that this set of normal muscle parameters can be used to help diagnose neuromuscular disorders. It will also facilitate follow-up in disease progression and therapy.