MR imaging findings in children with merosin-deficient congenital muscular dystrophy

BACKGROUND AND PURPOSE: Our purpose was to determine the brain MR imaging characteristics of merosin-deficient congenital muscular dystrophy in children. METHODS: We reviewed the MR imaging findings of the brain in three children with known merosin-deficient congenital muscular dystrophy to determine the presence of any cerebral or cerebellar abnormalities of development or abnormalities of the white matter. RESULTS: In all three patients, there was normal formation of the cerebrum, the cerebellum, and no evidence of neuronal migration anomalies. All three patients had abnormal white matter in the cerebrum, with sparing of the corpus callosum, internal capsule, cerebellum, and brain stem. CONCLUSION: MR imaging of the brain in children with merosin-deficient congenital muscular dystrophy reveals a consistent pattern of white matter abnormality. We postulate that disruption of the blood-brain barrier associated with merosin deficiency leads to increased water content, resulting in abnormal white matter signal intensity.     

MR imaging of myopathy

Magnetic resonance imaging was performed in 8 patients with muscle disease and 6 normal controls. High intensity areas of varying dimensions were found in thigh muscles of the patients with progressive muscular dystrophy (PMD) and congenital myopathy. Shortened T1 and prolonged T2 values with disease progression were characteristic. The T1 values were variable and prolonged, T2 values were more characteristic of progressive muscular degeneration. The T1 value may help to detect the early stage of PMD. Magnetic resonance imaging is useful in detecting the muscle lesions in PMD and essential for selection of a biopsy site.     

MRI在进行性肌营养不良中的应用价值

目的探讨进行性肌营养不良(progressive muscular dystrophy,PMD)的骨骼肌MRI表现与临床的相关性及其应用价值。资料与方法对22例经临床表现、血清肌酸激酶(CPK)、肌电图检查及开放式骨骼肌活检、组织及免疫病理学证实的PMD患者的临床及影像资料进行回顾性分析。结果各型肌病MRI受累肌肉分布特征为:杜兴型和贝克型为大腿前部肌群;肢带型2B型为大腿后部肌群;远端型中Welander型为大腿后部肌群及小腿前群、外侧群肌肉;Nonaka型为小腿前群、外侧群肌肉;Miyoshi型为小腿后部肌群;先天性为大、小腿后部肌群;强直性为大、小腿前、后肌群。MRI上的病变程度与病程无一致性关系。除假肥大型无肌肉水肿表现外,其余类型均有不同程度的肌肉水肿。结论 MRI表现提示不同的肌病类型有特定的分布,有助于临床鉴别某些类型的肌病。利用对脂肪沉积和水肿敏感的MRI序列,有助于理解肌病的病理过程,协助临床检查监测对治疗的反应。     

MRI of normal and pathologic skeletal muscle

Lower extremity skeletal muscle of 22 individuals (five normal volunteers and 17 patients with muscular or neuromuscular diseases) was studied with magnetic resonance imaging. Axial images generated with spin-echo pulse sequences using short repetition times (500-900 msec TR) and short echo times (30-60 msec TE) provided excellent contrast between fat (high signal intensity) and muscle (intermediate signal intensity). Seventeen patients with clinically verified muscle disorders were evaluated in a manner similar to the normal volunteers. Conditions studied include Duchenne muscular dystrophy (three patients), limb-girdle muscular dystrophy (five), facioscapulohumeral dystrophy (three), and spinal muscular atrophy, amyotrophic lateral sclerosis, hereditary sensorimotor neuropathy, cerebral palsy, poliomyelitis, and Kearn-Sayre mitochondrial muscle disease (one each). General patterns of muscle abnormality were common among the diseases and included decreased or increased muscle size and a spectrum of muscle replacement by fat. Variable patterns were observed within disease groups and for each patient. Much phosphorus-31 spectroscopy has been performed in a blind fashion with no proton map of normal/abnormal muscle distribution to guide the spectroscopist. This study emphasizes the worth of having a muscle proton map of patients with muscle dysfunction to assure that meaningful phosphorus spectroscopic information is obtained from a volume of tissue limited to an appropriate muscle.     

Imaging findings in three cases of the nodular type of muscular sarcoidosis

OBJECTIVE: Sarcoidosis is a granulomatous multisystem disorder that may uncommonly involve muscle. We report the sonographic and MRI findings in three cases of the nodular type of muscular sarcoidosis. CONCLUSION: Intramuscular hypoechoic well-defined nodules in young patients or patients with a history of sarcoidosis suggest the diagnosis of intramuscular sarcoid. MRI is useful in detecting muscle sarcoid, evaluating the extent and distribution of muscle involvement, and monitoring the patient during follow-up after steroid therapy. MRI showed nodules that were iso- or hyperintense relative to muscle on T1-weighted sequences. On T2-weighted images and STIR sequences, we observed numerous intramuscular nodules of homogeneous high signal intensity. All nodules enhanced homogeneously on contrast-enhanced T1-weighted sequences. Disappearance of all nodules was seen on follow-up sonograms and MR images after patients had received steroid therapy.     

Exercise-induced muscle modifications: study of healthy subjects and patients with metabolic myopathies with MR imaging and P-31 spectroscopy

Exercise-induced variations in proton signal intensity at magnetic resonance (MR) imaging and in intracellular pH were studied in the forearm muscles of healthy subjects and patients with muscular glycogenoses. The relative increase in T2 was measured from MR images obtained at 0.5 T, and end-exercise pH was measured with surface coil phosphorus-31 spectroscopy at 2 T. Eight healthy subjects showed a relative increase in T2 ranging from 20% to 44% in the flexor digitorum superficialis muscle and a drop in pH ranging from 0.35 to 1.1. Seven patients with muscular glycogenosis (six with McArdle disease and one with phosphofructokinase deficiency) showed only a slight variation in T2 (0%-17%) and no decrease in pH. Variations in T2 and in end-exercise pH were found to be correlated, perhaps reflecting the stimulation of muscular perfusion caused by acidosis.     

MR imaging findings of focal myositis: a pseudotumour that may mimic muscle neoplasm

Objective  The authors describe magnetic resonance (MR) findings in eight patients with histologically confirmed focal myositis. Materials and methods  In each patient, axial TSE T1-weighted and fast short-tau inversion recovery (STIR) images were obtained using a 1.5-T MR scanner. Three patients also underwent dynamic contrast-enhanced MR examination using a GE T1-weighted sequence. The following features were evaluated: anatomical distribution, extent of the involvement, signal intensity characteristics, dynamic enhancement pattern and outcome at follow-up examinations. Results  Seven of eight lesions were located in the lower extremities, one of eight in the arm; four of eight involved part of a muscle, two of eight diffusely involved a muscle and two of eight showed multifocal involvement of two or more muscles. All lesions were hyperintense on fast-STIR images: the hyperintensity was homogeneous in six of eight and inhomogeneous in two of eight. On T1-weighted unenhanced images, all lesions but two appeared isointense or slightly hypointense in comparison to normal muscles; two lesions showed a slight hyperintensity. Dynamic enhancement pattern corresponded to the type usually seen in benign soft tissue lesions. All lesions disappeared. Conclusion  Focal myositis is an uncommon pseudotumour which should be considered in the differential diagnosis of muscular masses and myopathies.     

CT muscle scanning in the evaluation of patients with spinal muscular atrophy (SMA)

Summary One hundred patients with spinal muscular atrophy (SMA) were assessed by CT scanning using a standardised technique. The spectrum of CT abnormality occuring in SMA was observed and by overall analysis the patients were divided into 4 groups. While the CT appearances of these groups correlated well with clinical assessment of severity of disease, the disease process was usually much more widespread than clinical examination suggested. CT abnormality was first observed in the leg and gluteal muscles, progressing to the posterior spinal, thigh, shoulder girdle and sternomastoid muscles. Hypertrophy of sartorius and gracilis was observed in a significant number of patients. Fascial planes were preserved in involved muscles in over half of the patients, even in late-stage disease. Asymmetrical muscle involvement was seen with increasing frequency as the disease process increased in extent as evaluated by CT scanning. There was no discernible difference in the CT appearances in those patients who clinically had limb-girdle, facioscapulohumeral or scapuloperoneal distribution of weakness.     

Muscle MRI findings in facioscapulohumeral muscular dystrophy

Objectives

Facioscapulohumeral muscular dystrophy (FSHD) is characterized by extremely variable degrees of facial, scapular and lower limb muscle involvement. Clinical and genetic determination can be difficult, as molecular analysis is not always definitive, and other similar muscle disorders may have overlapping clinical manifestations.

Methods and Materials

Whole-body muscle MRI examination for fat infiltration, atrophy and oedema was performed to identify specific patterns of muscle involvement in FSHD patients (30 subjects), and compared to a group of control patients (23) affected by other myopathies (NFSHD).

Results

In FSHD patients, we detected a specific pattern of muscle fatty replacement and atrophy, particularly in upper girdle muscles. The most frequently affected muscles, including paucisymptomatic and severely affected FSHD patients, were trapezius, teres major and serratus anterior. Moreover, asymmetric muscle involvement was significantly higher in FSHD as compared to NFSHD patients.

Conclusions

In conclusion, muscle MRI is very sensitive for identifying a specific pattern of involvement in FSHD patients and in detecting selective muscle involvement of non-clinically testable muscles. Muscle MRI constitutes a reliable tool for differentiating FSHD from other muscular dystrophies to direct diagnostic molecular analysis, as well as to investigate FSHD natural history and follow-up of the disease.

Key Points

? Muscle MRI identifies a specific pattern of muscle involvement in FSHD patients. ? Muscle MRI may predict FSHD in asymptomatic and severely affected patients. ? Muscle MRI of upper girdle better predicts FSHD. ? Muscle MRI may differentiate FSHD from other forms of muscular dystrophy. ? Muscle MRI may show the involvement of non-clinical testable muscles.

     

Magnetic resonance imaging, ultrasound and real-time ultrasound elastography of the thigh muscles in congenital muscle dystrophy

Congenital muscle dystrophy includes a range of genetic disorders characterized by muscle weakness and contractures. We report the magnetic resonance (MR), ultrasound (US) and real-time sonoelastography (RTE) imaging findings of the thigh muscles of a 15-year-old boy with Bethlem myopathy diagnosed with clinical, electromyographic and histopathological criteria. Ultrasound and MR showed hyperechoic appearance and high signal intensity on T1- and T2-weighted sequences respectively at the periphery of the vastus lateralis and the long head of the biceps femoris muscles, and at a central area within the rectus femoris muscles. RTE was employed to examine the elastic properties of the muscle. The elastograms were presented as colour-coded maps superimposed on the B-mode images and revealed that the elastographic pattern correlated with the MR and US pattern of involvement. The abnormal muscle areas were stiffer (blue) than the normal-appearing areas (green), a finding that probably correlates with the presence of dystrophic collagen at the affected areas. This report suggests that RTE could be used as an additional imaging tool to evaluate the pattern of muscle changes in congenital myopathy. Further studies are needed to investigate the specificity and clinical value of RTE in the diagnosis and monitoring of neuromuscular disease.     

平山病的MRI诊断价值

目的:探讨平山病的MR表现和价值,认识平山病的临床特征和可能的发病机制.方法:5例经临床确诊的平山病患者均隐匿起病,病变局限于上肢远端肌肉,4例单侧上肢前臂受累,1例双侧不对称性受累.5例患者均行颈椎X线平片检查,及颈髓常规自然体位MR平扫及屈颈位平扫 增强扫描.所有患者均进行常规生化检查,脑脊液检查,肌电图检查和肌肉活检.结果:5例患者普通X线检查4例可见颈椎生理曲度变直,自然体位MR平扫3例有低位脊髓萎缩变扁(萎缩水平在颈5-胸1,最明显在颈6水平),2例萎缩的脊髓内信号异常.曲颈MR检查时,除了可见自然体位MR的表现外,5例患者均可见特征性的颈髓前移、变平,硬脊膜向前移位,硬脊膜外腔增宽,4例患者在增宽的硬膜外腔均可见流空血管信号,增强扫描5例患者在增宽的硬脊膜外腔均可见强化的静脉丛.结论:平山病的MR表现存在一定的特征性,MR屈曲位平扫 增强扫描对平山病的诊断及其发病机制的理解有重要的价值.     

Magnetization transfer imaging of skeletal muscle in autosomal recessive limb girdle muscular dystrophy.

PURPOSE: The purpose of this work was to characterize magnetization transfer (MT) contrast of skeletal muscles in limb girdle muscular dystrophy (LGMD). METHOD: The calf muscles of five LGMD patients and 10 normal volunteers were imaged with an off-resonance MT suppression pulse applied to T1-weighted images. MT suppression ratios were calculated for anterior tibialis, posterior tibialis, soleus, and gastrocnemius muscles in the LGMD and control groups. The relationship between MT of individual muscles and the duration of LGMD symptoms was determined. RESULTS: Strong MT contrast was observed in normal calf muscles, with mean (+/-SD) suppression ratios ranging from 37.9% (+/-3.0) to 41.1% (+/-2.1). In diseased muscle, MT signal suppression ranged from 11 to 38%, demonstrating an inverse relationship between symptom duration and suppression ratios. MT contrast in the LGMD patients, as a reflection of muscle tissue integrity, was preserved in posterior or anterior tibialis, soleus, and gastrocnemius muscles, respectively. Suppression ratios were dramatically reduced in muscles with gross fatty infiltration but also were reduced in muscle tissues without visual evidence of fatty infiltration. CONCLUSION: MT imaging provides a quantitative measure of pathologic changes occurring within the skeletal muscles of patients with LGMD relative to normal and may be useful in evaluating disease extent, progression, and response to new therapies as they become available.     

Hereditary neuromuscular diseases

This article presents the actual classification of neuromuscular diseases based on present expansion of our knowledge and understanding due to genetic developments. It summarizes the genetic and clinical presentations of each disorder together with CT findings, which we studied in a large group of patients with neuromuscular diseases. The muscular dystrophies as the largest and most common group of hereditary muscle diseases will be highlighted by giving detailed information about the role of CT and MRI in the differential diagnosis. The radiological features of neuromuscular diseases are atrophy, hypertrophy, pseudohypertrophy and fatty infiltration of muscles on a selective basis. Although the patterns and distribution of involvement are characteristic in some of the diseases, the definition of the type of disease based on CT scan only is not always possible.     

MR imaging of the muscular component of myocutaneous flaps in the head and neck

BACKGROUND AND PURPOSE: Myocutaneous flaps are commonly used for reconstruction in head and neck surgery. The purpose of this study was to characterize the MR imaging findings of the muscular component of these flaps, with an emphasis on enhancement patterns. Recognition of these imaging findings is important in differentiating postoperative changes from recurrent tumor. METHODS: MR studies were evaluated in 25 patients who had undergone 27 flap reconstructions after resection of a head and neck tumor. Twenty were free flaps and seven were pedicled rotation flaps, and a dominant component of all flaps was muscle. MR images were reviewed for signal intensity, enhancement characteristics, and morphology over a period of 7 to 79 months. RESULTS: On baseline postoperative images, 21 flaps showed moderate or intense enhancement of the muscular graft component relative to nonenhancing native muscle, three flaps showed mild enhancement, and three showed no enhancement. On follow-up images, 18 flaps that initially had intense enhancement showed persistent intense enhancement, and three showed decreasing enhancement. Two flaps with initial mild enhancement were unchanged on follow-up, and one became nonenhancing. None of the initially nonenhancing flaps subsequently enhanced. T1 signal intensity of muscular graft components was always isointense with normal muscle, whereas T2 signal intensity was variable and tended to be stable. Ninety-three percent of our muscular flap components showed striations typical of normal muscle and were best identified on T1-weighted images. No significant imaging differences were found between pedicled and free flaps. CONCLUSION: Most muscular flap components show moderate or intense enhancement on fat-suppressed contrast-enhanced MR images that may persist for many months and be quite striking. Radiologists should be familiar with the typical postoperative appearance of predominantly muscular flaps to avoid misdiagnosis as tumor extension or recurrence.     

Systemic manifestations of idiopathic inflammatory myopathies--part one]

Dermatomyositis and polymyositis are the idiopathic inflammatory myopathies of autoimmune origin. Apart from muscle weakness, general symptoms such as the affection of visceral organs and altered indicators of humeral immunity occur in a minority of patients. The aim of the study was to establish whether the systemic manifestations of the disease, altered immunoserologic parameters and findings of muscle vasculitis occurred more frequently in patients with dermatomyositis or polymyositis. The frequency of clinic, serologic and histopathologic alterations in the groups of patients with dermatomyositis and polymyositis was determined. In order to determine the degree and importance of the frequency, the following parameters were calculated: the relative rations of frequencies and the importance of the difference in frequencies of particular alterations between the groups of patients. It was found that extramuscular manifestations of the disease such as arthritis, pulmonary, cardiac and renal changes, the increased activity of C3 and C4 complement components as well as vasculitis of muscle and skin tissue occurred more frequently in patients with dermatomyositis. This finding indicates that patients with DM, regardless of the degree of muscular affection, may have a more severe clinical course of the disease and a poor prognosis.     

Quantification of fat infiltration in oculopharyngeal muscular dystrophy: comparison of three MR imaging methods

Purpose

To analyze and compare three quantitative MRI methods to determine the degree of muscle involvement in oculopharyngeal muscular dystrophy (OPMD).

Materials and Methods

Muscle fat content (MFC) was determined based on water–fat quantification using a 2‐point Dixon (2PD) method and on a histogram analysis of the free induction decay (FID) signal of a gradient‐spoiled steady‐state free precession (SSFP) sequence. In addition, transverse relaxation times (T₂) of muscle tissue were calculated using a monoexponential decay model.

Results

We observed an increased mean MFC in OPMD patients as compared to healthy controls with the adductor magnus and soleus muscles being the most involved muscles in the thigh and calf, respectively. Furthermore, strong correlations (0.78 < R² < 0.94) between different quantitative MR methods were observed. Fewer outliers, however, were obtained by the 2PD method and T₂ measurements, suggesting these methods being superior to the SSFP‐FID method.

Conclusion

Quantitative MR techniques, such as fast multiecho Dixon methods and T₂ imaging, can reliably differentiate between healthy and dystrophic muscles in OPMD, even if muscles are only marginally affected. Quantitative methods thus represent a promising tool that may be able to monitor more objectively the individual disease progression and treatment response in future clinical trials in muscular dystrophies. J. Magn. Reson. Imaging 2011;33:203–210. © 2010 Wiley‐Liss, Inc.     

MRI assessment of paraspinal muscles in patients with acute and chronic unilateral low back pain

Objective:

To investigate the changes in paraspinal muscle cross-sectional area (CSA) and composition, using the digital data from lumbar spine MRIs of patients with acute and chronic low back pain (LBP).

Methods:

In total, 178 patients with unilateral LBP who had lumbar MRI examination were recruited. The data were obtained by a retrospective documentation audit. The CSAs and mean signal intensities of the bilateral paraspinal muscles [psoas major (PM), quadratus lumborum, multifidus (MF) and erector spinae (ES)] were measured, and the percentage of fat infiltration was calculated. The data between the painful side and non-painful side were compared, and between-group comparisons were tested. 42 patients with chronic unilateral LBP could indicate the problem level, and the CSA and mean signal intensity of the MF muscle were analysed at the problem level, and one vertebral above and one vertebral level below the problem level.

Results:

The CSAs of the PM and ES muscles were significantly decreased in the acute LBP group, while in the chronic LBP group, significant reduction in CSA was found in the MF and ES muscles on the painful side compared with the non-painful side. The mean signal intensity and fat content of the ES muscle on the painful side in the chronic LBP group was significantly higher than that on the painful side in the acute LBP group. The significant decrease of CSA in the MF muscle was found at multiple levels on the painful side.

Conclusion:

The present findings show that there is selective ipsilateral atrophy of paraspinal muscles, specific to the symptomatic side, in patients with acute and chronic LBP. The reduction of the muscle CSA and increased fatty infiltration occurred synchronously, and the extent of change is significantly greater in chronic LBP in the ES muscle. Atrophy of the MF muscle appears to be at multiple levels but side specific in relation to symptoms in patients with chronic LBP, and the decreased muscle CSA may occur prior to fatty infiltration.

Advances in knowledge:

There are specific paraspinal muscles undergoing atrophy and fatty infiltration in patients with acute and chronic LBP on the symptomatic side. The CSA of the MF muscle decreased at multiple levels on the symptomatic side in patients with chronic unilateral LBP, which may occur prior to fatty infiltration.     

Signal intensity, clinical activity and cross-sectional areas on MRI scans in thyroid eye disease

The signal intensity from inflamed extra-ocular muscles on short tau inversion recovery (STIR)-sequence magnetic resonance imaging (MRI) is known to correlate with clinical scores of thyroid eye disease (TED) severity. Twenty-one patients who had undergone repeated MRI scanning for TED were studied retrospectively. Signal intensity of extra-ocular muscles (from STIR-sequence MRI) and cross-sectional area (from STIR and T1 MRI) were correlated with Mourits' clinical activity score (CAS). The area of highest signal intensity within the most inflamed extra-ocular muscle, and the average cross-sectional signal intensity of the most inflamed extra-ocular muscle reliably correlated with CAS, and this was maintained as disease activity changed over time. In contrast, isolated measures of muscle cross-sectional area did not correlate with CAS. The extra-ocular muscle cross-sectional area calculated from STIR-sequence MR images was greater than that measured on T1 images. This suggests that muscle area from STIR-sequence MRI may also detect peri-muscular inflammation. We conclude that the peak signal intensity from the most inflamed extra-ocular muscle remains the most reliable correlate of clinical disease activity obtained from these images. STIR-sequence MRI scans provide a number of useful measures of disease activity in TED.     

Acute swelling of the limbs: magnetic resonance pictorial review of fascial and muscle signal changes.

OBJECTIVE: This pictorial review analyzes the magnetic resonance (MR) fascial/muscular changes in 69 patients referred as emergencies with acute swelling of the limbs (ASL) from various causes. METHODS AND MATERIAL: A prospective MR imaging (MRI) study of 69 patients referred as emergencies for ASL was performed. Our population consisted of 45 patients with skin and soft-tissue infections (cellulitis and necrotizing fasciitis, and pyomyositis), six patients with soft-tissue inflammatory diseases (dermatomyositis, graft-versus-host disease), 11 patients with acute deep venous thrombosis, three patients with rhabdomyolysis, one patient with acute denervation and three other patients with rare diseases. Hematomas, tumorous or infectious bone involvement and soft-tissue tumors were excluded. All studies included spin echo T1-weighted images and spin echo T2-weighted images. Gadolinium-enhanced spin echo T1-weighted images were obtained when an abscess was suspected on T2-weighted images. Selective fat-saturated T1- and T2-weighted sequences were also used. MRI analysis was performed to obtain a compartmentalized anatomical approach according to the location of signal abnormalities in subcutaneous fat, superficial and deep fascia and muscle. RESULTS: In all patients with ASL, MRI demonstrated soft-tissue abnormalities involving subcutaneous fat, superficial fascia, deep fascia, or muscle. Although MR findings were non-specific, MRI appears sensitive for detecting subtle fascial and muscle signal changes. CONCLUSIONS: In skin and soft-tissue infections, MRI can be helpful for therapeutic management by determining the depth of soft-tissue involvement, particularly within fasciae and muscles, which is partly related to the severity of cellulitis with severe systemic manifestations. MRI can also aid the surgeon in diagnosing abscesses. In inflammatory diseases, MRI can determine the best site for biopsy and also monitor therapeutic response.     

Neuromuscular diseases: evaluation with high-frequency sonography

Forty-four patients with clinically suspected neuromuscular disease and 12 healthy volunteers underwent high-frequency ultrasound examination of the rectus femoris, vastus medialis, vastus lateralis, and biceps brachii muscles, and the number of perimysial septa was determined. These numbers and muscle/soft-tissue ratios of the lower extremity were compared. Findings were correlated with results of muscle biopsy in all patients with suspected disease. Using the number of perimysial septa in the lower extremity, the authors found significant differences between the muscles of healthy volunteers and those of patients with Duchenne muscular dystrophies, other muscular dystrophies, and spinal muscular atrophies: The receiver operating characteristic curve showed that an average of 12 perimysial septa within 1 cm of muscle is the ideal cutoff value to differentiate subjects without morphologic changes from those with pathologic findings. The authors conclude that this measurement is useful for differentiation of neuromuscular diseases and may be a noninvasive, reproducible means with which to evaluate disease progression.