1H Magnetic resonance spectroscopy findings in idiopathic inflammatory myopathies at 3 T: feasibility and first results

Decreased Muscular Perfusion in Dermatomyositis: Initial Results Detected by Inflow-Based Vascular-Space-Occupancy MRI

OBJECTIVE. This study aimed to determine whether inflow-based vascular-space-occupancy (iVASO) MRI could reproducibly quantify skeletal muscle perfusion and differentiate patients with dermatomyositis (DM) from healthy subjects. MATERIALS AND METHODS. A total of 25 patients with DM and 22 healthy volunteers underwent iVASO MRI in a 3-T MRI scanner. Maximum and mean arteriolar muscle blood volume (MBV) values of four subgroups of muscles (normal muscles, morphologically normal-appearing muscles, edematous muscles, and atrophic or fat-infiltrated muscles) were obtained. Maximum and mean arteriolar MBV values were compared among the different subgroups, and repeat testing was performed in 20 subjects to assess reproducibility. RESULTS. Compared with normal muscles in healthy subjects, morphologically normal-appearing muscles, edematous muscles, and atrophic or fat-infiltrated muscles in patients with DM showed a significant decrease of both maximum and mean arteriolar MBV (p < .001). Both parameters were significantly lower in atrophic or fat-infiltrated muscles than in morphologically normal-appearing and edematous muscles (p < .001). ROC AUCs for discriminating patients with DM from healthy volunteers were 0.842 and 0.812 for maximum and mean arteriolar MBV values, respectively. As a measure of test-retest studies, the intraclass correlation coefficients (ICCs) were 0.990 (95% CI, 0.986-0.993) and 0.990 (95% CI, 0.987-0.993) for maximum and mean arteriolar MBV, respectively. For interobserver reproducibility, the ICCs were 0.989 (95% CI, 0.986-0.991) and 0.980 (95% CI, 0.975-0.983), respectively. CONCLUSION. iVASO MRI can reproducibly quantify arteriolar MBV in the thigh and discriminate between healthy volunteers and patients with DM.

Established paths and new avenues: a review of the main radiological techniques for investigating sarcopenia

Sarcopenia is a clinical condition mainly affecting the elderly that can be associated in a long run with severe consequences like malnutrition and frailty. Considering the progressive ageing of the world population and the socio-economic impact of this disease, much effort is devoted and has to be further focused on an early and accurate diagnostic assessment of muscle loss. Currently, several radiological techniques can be applied for evaluating sarcopenia. If dual-energy X-ray absorptiometry (DXA) is still considered the main tool and it is even recommended as reference by the most current guidelines of the European working group on sarcopenia in older people (EWGSOP), the role of ultrasound (US), computed tomography (CT), peripheral quantitative CT (pQCT), and magnetic resonance imaging (MRI) should not be overlooked. Indeed, such techniques can provide robust qualitative and quantitative information. In particular, regarding MRI, the use of sequences like diffusion-weighted imaging (DWI), diffusion tensor imaging (DTI), magnetic resonance spectroscopy (MRS) and mapping that could provide further insights into the physiopathological features of sarcopenia, should be fostered. In an era pointing to the quantification and automatic evaluation of diseases, we call for future research extending the application of organ tailored protocols, taking advantage of the most recent technical developments.

Advances in Quantitative Imaging of Genetic and Acquired Myopathies: Clinical Applications and Perspectives

In the last years, magnetic resonance imaging (MRI) has become fundamental for the diagnosis and monitoring of myopathies given its ability to show the severity and distribution of pathology, to identify specific patterns of damage distribution and to properly interpret a number of genetic variants. The advances in MR techniques and post-processing software solutions have greatly expanded the potential to assess pathological changes in muscle diseases, and more specifically of myopathies; a number of features can be studied and quantified, ranging from composition, architecture, mechanical properties, perfusion, and function, leading to what is known as quantitative MRI (qMRI). Such techniques can effectively provide a variety of information beyond what can be seen and assessed by conventional MR imaging; their development and application in clinical practice can play an important role in the diagnostic process and in assessing disease course and treatment response. In this review, we briefly discuss the current role of muscle MRI in diagnosing muscle diseases and describe in detail the potential and perspectives of the application of advanced qMRI techniques in this field.

Advanced MRI Techniques for Muscle Imaging

Advanced magnetic resonance imaging (MRI) techniques can evaluate a wide array of muscle pathologies including acute or chronic muscle injury, musculotendinous response to injury, intramuscular collections and soft tissue masses, and others. In recent years, MRI has played a more important role in muscle disease diagnosis and monitoring. MRI provides excellent spatial and contrast resolution and helps direct optimal sites for muscle biopsy. Whole-body MRI now helps identify signature patterns of muscular involvement in large anatomical regions with relative ease. Quantitative MRI has advanced the evaluation and disease tracking of muscle atrophy and fatty infiltration in entities such as muscular dystrophies. Multivoxel magnetic resonance spectroscopy (MRS) now allows a more thorough, complete evaluation of a muscle of interest without the inherent sampling bias of single-voxel MRS or biopsy. Diffusion MRI allows quantification of muscle inflammation and capillary perfusion as well as muscle fiber tracking.

Value of MRI in diagnostics and evaluation of myositis

PURPOSE OF REVIEW

This review aims at covering the role of muscle MRI in supporting the diagnosis of myositis, in aiding to differentiate it from other muscle disorders, and in monitoring myositis patients over time by assessing response to treatment and by discriminating between muscle inflammation and chronic damage.

RECENT FINDINGS

MRI can assist in 'pattern recognition' of muscle involvement across numerous myopathies, including myositis. Novel applications of magnetic resonance such as cardiac MRI, MR elastography and blood oxigenation level-dependent magnetic resonance can shed light on different aspects of myositis and usefully complement conventional MRI in assessing patients with myositis.

SUMMARY

MRI can guide therapy by determining whether muscle weakness is related to edema (active inflammation) or muscle atrophy/fat replacement (chronic damage). There is a need to better standardize the assessment of MRI findings in myositis to provide defined outcome measures for use in clinical trials. VIDEO ABSTRACT.

Pathophysiological Concepts and Treatment of Camptocormia

Camptocormia is a disabling pathological, non-fixed, forward bending of the trunk. The clinical definition using only the bending angle is insufficient; it should include the subjectively perceived inability to stand upright, occurrence of back pain, typical individual complaints, and need for walking aids and compensatory signs (e.g. back-swept wing sign). Due to the heterogeneous etiologies of camptocormia a broad diagnostic approach is necessary. Camptocormia is most frequently encountered in movement disorders (PD and dystonia) and muscles diseases (myositis and myopathy, mainly facio-scapulo-humeral muscular dystrophy (FSHD)). The main diagnostic aim is to discover the etiology by looking for signs of the underlying disease in the neurological examination, EMG, muscle MRI and possibly biopsy. PD and probably myositic camptocormia can be divided into an acute and a chronic stage according to the duration of camptocormia and the findings in the short time inversion recovery (STIR) and T1 sequences of paravertebral muscle MRI. There is no established treatment of camptocormia resulting from any etiology. Case series suggest that deep brain stimulation (DBS) of the subthalamic nucleus (STN-DBS) is effective in the acute but not the chronic stage of PD camptocormia. In chronic stages with degenerated muscles, treatment options are limited to orthoses, walking aids, physiotherapy and pain therapy. In acute myositic camptocormia an escalation strategy with different immunosuppressive drugs is recommended. In dystonic camptocormia, as in dystonia in general, case reports have shown botulinum toxin and DBS of the globus pallidus internus (GPi-DBS) to be effective. Camptocormia in connection with primary myopathies should be treated according to the underlying illness.

Thigh magnetic resonance imaging for the evaluation of disease activity in patients with idiopathic inflammatory myopathies followed in a single center

INTRODUCTION

In patients with idiopathic inflammatory myopathies (IIM), magnetic resonance imaging (MRI) has been proposed as a useful tool for diagnosis and follow-up. It may identify muscle inflammation (edema) and fatty infiltration for evaluation of disease activity and damage. Little information is available on the role of MRI in assessment of large cohorts of adult patients with IIM.

METHODS

Fifty-one patients underwent MRI of the thigh muscles, laboratory tests, and clinical evaluation, including Physician Global Assessment (PGA) of myositis activity and the Manual Muscle Test 8 (MMT8).

RESULTS

Muscle edema correlated significantly with creatine kinase values (P = 0.017) and PGA (P < 0.001). A significant correlation between edema and MMT8 values (P = 0.025) was observed when patients with muscle fatty infiltration were excluded. With respect to clinical diagnosis, the sensitivity of MRI was 92.3%, and specificity was 83.3%.

CONCLUSIONS

MRI appears to provide additional information that complements clinical and biochemical examinations. Muscle Nerve 54: 666-672, 2016.

Imaging: seeing muscle in new ways

PURPOSE OF REVIEW

The idiopathic inflammatory myopathies are diseases that can be difficult to diagnose and evaluate, but diagnosis has been improved by modern imaging techniques. Advances in imaging continue to be made. Therefore, it is necessary to evaluate the implications of these advances for the diagnosis, understanding, and management of muscle diseases.

RECENT FINDINGS

There have been advances in imaging across multiple modalities. Several new radiotracers show an improved ability to focus on inflammation better than older agents. Magnetic resonance spectroscopy has shown the ability to diagnose several idiopathic inflammatory myopathy mimics. MRI reveals previously unknown areas of disease when used for full-body imaging. Ultrasound has the ability to differentiate inclusion body myositis from other myopathies.

SUMMARY

Currently, MRI and ultrasound offer the most information about these diseases in a given patient, and new advances in these fields have served to only make them more useful. New advances in nuclear imaging and magnetic resonance spectroscopy are showing that they have utility as well, and advances in these techniques may allow them to come to the forefront in evaluating difficult idiopathic inflammatory myopathy patients.

Role of MR spectroscopy in musculoskeletal imaging

Magnetic resonance spectroscopy (MRS) is an imaging approach that allows for the noninvasive molecular characterization of a region of interest. By detecting signals of water, lipids, and other metabolites, MRS can provide metabolic information for lesion characterization and assessment of treatment response. Although MRS has been routinely used in the brain, clinical applications within the musculoskeletal system have only more recently emerged. The aim of this article is to review the technical considerations for performing MRS in the musculoskeletal system, focusing on proton MRS, and to discuss its potential roles in musculoskeletal tumor imaging and the assessment of muscle physiology and disease.

Proton magnetic resonance spectroscopy of skeletal muscle: a comparison of two quantitation techniques

RATIONALE AND OBJECTIVES

The aim of this study was to develop and compare two methods for quantification of metabolite concentrations in human skeletal muscle using phased-array receiver coils at 3T.

MATERIALS AND METHODS

Water suppressed and un-suppressed spectra were recorded from the quadriceps muscle (vastus medialis) in 8 healthy adult volunteers, and from a calibration phantom containing 69mM/L N-acetyl aspartate. Using the phantom replacement technique, trimethylamine specifically [TMA] and creatine [Cr] concentrations were estimated, and compared to those values obtained by using the water reference method.

RESULTS

Quadriceps [TMA] concentrations were 9.5±2.4 and 9.6±4.1mmol/kg wet weight using the phantom replacement and water referencing methods respectively, while [Cr] concentrations were 26.8±12.2 and 24.1±5.3mmol/kg wet weight respectively.

CONCLUSIONS

Reasonable agreement between water referencing and phantom replacement methods was found, although for [Cr] variation was significantly higher for the phantom replacement technique. The relative advantages and disadvantages of each approach are discussed.