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Background: Magnetic resonance imaging (MRI) is the dominant 3D imaging modality to quantify muscle properties in skeletal muscle disorders, in inherited and acquired muscle diseases, and in sarcopenia, in cachexia and frailty., Methods: This review covers T1 weighted and Dixon sequences, introduces T2 mapping, diffusion tensor imaging (DTI) and non-proton MRI. Technical concepts, strengths, limitations and translational aspects of these techniques are discussed in detail. Examples of clinical applications are outlined. For comparison 31 P-and 13 C-MR Spectroscopy are also addressed., Results: MRI technology provides a rich toolset to assess muscle deterioration. In addition to classical measures such as muscle atrophy using T1 weighted imaging and fat infiltration using Dixon sequences, parameters characterizing inflammation from T2 maps, tissue sodium using non-proton MRI techniques or concentration or fiber architecture using diffusion tensor imaging may be useful for an even earlier diagnosis of the impairment of muscle quality., Conclusion: Quantitative MRI provides new options for muscle research and clinical applications. Current limitations that also impair its more widespread use in clinical trials are lack of standardization, ambiguity of image segmentation and analysis approaches, a multitude of outcome parameters without a clear strategy which ones to use and the lack of normal data., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. KE is a part time and MABE a full time employee of Clario, Inc., (© 2023 The Authors.)

X-linked hypophosphatemia (XLH) is the most common form of inheritable rickets. The disease is caused principally by PHEX mutations leading to increased concentrations of circulating intact FGF23, hence renal phosphate wasting, hypophosphatemia, and decreased circulating levels of 1,25(OH) 2 vitamin D. The chronic hypophosphatemia leads to rickets and osteomalacia through a combination of mechanisms, including a lack of endochondral ossification and impaired mineralization. Imaging has a major role in determining the diagnosis of rickets and its cause, detecting complications as early as possible, and helping in treatment monitoring., (Copyright © 2021. Published by Elsevier Masson SAS.)

The radiological assessment of muscle properties-size, mass, density (also termed radiodensity), composition, and adipose tissue infiltration-is fundamental in muscle diseases. More recently, it also became obvious that muscle atrophy, also termed muscle wasting, is caused by or associated with many other diseases or conditions, such as inactivity, malnutrition, chronic obstructive pulmonary disorder, cancer-associated cachexia, diabetes, renal and cardiac failure, and sarcopenia and even potentially with osteoporotic hip fracture. Several techniques have been developed to quantify muscle morphology and function. This review is dedicated to quantitative computed tomography (CT) of skeletal muscle and only includes a brief comparison with magnetic resonance imaging. Strengths and limitations of CT techniques are discussed in detail, including CT scanner calibration, acquisition and reconstruction protocols, and the various quantitative parameters that can be measured with CT, starting from simple volume measures to advanced parameters describing the adipose tissue distribution within muscle. Finally, the use of CT in sarcopenia and cachexia and the relevance of muscle parameters for the assessment of osteoporotic fracture illustrate the application of CT in two emerging areas of medical interest.

Purpose: The purpose of this study was to evaluate, during a national workshop, the inter-observer variability in target volume delineation for primary extremity soft tissue sarcoma radiation therapy., Methods and Materials: Six expert sarcoma radiation oncologists (members of French Sarcoma Group) received two extremity soft tissue sarcoma radiation therapy cases 1: one preoperative and one postoperative. They were distributed with instructions for contouring gross tumour volume or reconstructed gross tumour volume, clinical target volume and to propose a planning target volume. The preoperative radiation therapy case was a patient with a grade 1 extraskeletal myxoid chondrosarcoma of the thigh. The postoperative case was a patient with a grade 3 pleomorphic undifferentiated sarcoma of the thigh. Contour agreement analysis was performed using kappa statistics., Results: For the preoperative case, contouring agreement regarding GTV, gross tumour volume GTV, clinical target volume and planning target volume were substantial (kappa between 0.68 and 0.77). In the postoperative case, the agreement was only fair for reconstructed gross tumour volume (kappa: 0.38) but moderate for clinical target volume and planning target volume (kappa: 0.42). During the workshop discussion, consensus was reached on most of the contour divergences especially clinical target volume longitudinal extension. The determination of a limited cutaneous cover was also discussed., Conclusion: Accurate delineation of target volume appears to be a crucial element to ensure multicenter clinical trial quality assessment, reproducibility and homogeneity in delivering RT. radiation therapy RT. Quality assessment process should be proposed in this setting. We have shown in our study that preoperative radiation therapy of extremity soft tissue sarcoma has less inter-observer contouring variability., (Copyright © 2018 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.)

Radiation-induced sarcoma is a long-term complication of radiation therapy. The most common secondary neoplasia is the undifferentiated pleomorphic sarcoma, which is usually described in the deep soft tissue of the trunk or extremities. Radiation-induced sarcomas have a poor prognosis. An early diagnosis and management are needed to improve the survival rate of such patients. We presently report a case of a radiation-induced undifferentiated pleomorphic sarcoma of the left gluteus maximus muscle, which developed 25 years after an initial diagnosis of aggressive fibromatosis and 21 years after a tumour recurrence. This case study illustrates the risk of developing a sarcoma in a radiation field and the need for long-term follow-up after radiation therapy. Unnecessary radiation therapy, in particular in the case of benign conditions in young patients, should be avoided., (Copyright © 2015 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.)

We aimed to assess the impact of osteoid osteomas of the hip on the size and fatty infiltration of the muscle thigh in 42 patients. The thigh circumference, cross-sectional areas, and fatty atrophy of four anterior muscles were assessed on magnetic resonance axial T1-weighted images. A significant fatty atrophy was found in the studied muscles of the ipsilateral thigh except for the rectus femoris. No significant association was demonstrated with pain duration suggesting that muscle atrophy may rather be related to the locoregional inflammation than subsequent to the disuse of the limb., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Introduction: The prevalence of vertebral sarcoidosis is highly variable (1 to 36% of reported case series). Because of limited clinical expression, its frequency is probably underestimated. Its proper management is not clearly defined., Case Report: A 42-year-old woman who had a past medical history of cutaneous and pulmonary sarcoidosis presented with low back pain that was refractory to usual medical treatment. A diagnosis of vertebral localisation of sarcoidosis was considered on the history of proven sarcoidosis, radiological features, and the absence of evidence of an alternative diagnosis. In the absence of other clinical or biological evidence of active sarcoidosis, a simple follow-up was planned. MRI control at 1 year showed the resolution of vertebral sarcoidosis lesions., Conclusion: Spontaneous regression is a possible outcome of vertebral sarcoidosis. Initiation of a specific treatment should be discussed in the absence of other visceral involvement., (Copyright © 2012 Société nationale française de médecine interne (SNFMI). Published by Elsevier SAS. All rights reserved.)

Electroneuromyography (ENMG) is the gold standard tool in evaluating peripheral neuropathies, and it is essential to the diagnosis and the location of the involvement, as well as the assessment of the severity and the prognosis of the lesion. However, it has also limitations. It is highly examiner dependant and because it is unpleasant, the assessment of some nerves and muscles is limited. The evaluation of proximal nerve and deep muscles is difficult to perform. Magnetic resonance imaging and echography represent a fast growing field in demyelinating and motor neuropathy assessment, while these imaging procedures are now well validated in myopathies. In this article, we discuss sensitivity, specificity and prognostic data brought up by these new imaging tools compared to ENMG and the significant future prospects they offer., (Copyright 2009 Société nationale française de médecine interne (SNFMI). Published by Elsevier SAS. All rights reserved.)

The prevalence of neurological complications in patients with osteoporotic vertebral collapse and the risk factors for neurological compromise were studied retrospectively in 138 inpatients. Six per cent of patients had objective neurological loss. Patients with neurological loss were more likely to have changes suggestive of malignant disease on roentgenograms, computed tomography, and magnetic resonance imaging. Diagnosis was based on magnetic resonance imaging and examination of vertebral biopsy specimens. Comparison of patients with and without neurological loss suggested that an intravertebral vacuum phenomenon and/or a cortical osteoporosis may cause fracture of the posterior wall and therefore compression of neurological structures.

Erdheim-Chester disease is an endogenous, non-genetically-determined lipidosis characterized by infiltrates of foamy, lipid-laden histiocytes and by bilateral symmetric foci of sclerosis in appendicular long bones. The clinical spectrum ranges from focal bone lesions to systemic disease with life-threatening visceral involvement. In one third of patients, roentgenograms show focal osteolysis within areas of sclerosis. Authors report a new case of Erdheim-Chester disease documented by two bone biopsies in different sites. Features in their patient included: 1) osteolysis and sclerosis of the long bones of the limbs and maxillas, with CT scan evidence of cortical rupture; 2) on magnetic resonance imaging studies, heterogeneous foci of decreased signal intensity on T1 images and heterogeneous areas of moderately increased signal intensity on T2-weighted images; 3) increased serum osteocalcin levels; 4) laboratory evidence of chronic inflammation with no extraosseous manifestations. The clinical, radiological, and pathological features of Erdheim-Chester disease are different from those of Langerhans cell histiocytosis. However, three cases of patients with both conditions have been reported in the literature, suggesting that there may be links between the two diseases.

Eight cases of spinal sarcoma complicating Paget's disease seen in different centers were reviewed. Clinical and radiological features of this condition were determined on the basis of these 8 cases and of 51 previously published cases. In the current series as well as in previous reports, most cases involved the lumbar and sacral spine and manifested as low back pain with sciatica and early development of neurological deficits. Roentgenographic diagnosis proved difficult because of the anatomic complexity of the spine and architectural changes characteristic of the pagetic bone. The most common radiological features was a mixed pattern with both sclerosis and central osteolysis. Computed tomography performed in one patient of current series disclosed osteolysis of the sacrum (not visible on plain roentgenograms) with tumor spread to adjacent soft tissues. Features shared by spinal and nonspinal sarcomas complicating Paget's disease include advanced mean age of patients, predominance of osteogenic sarcomas among histologic forms, increased risk of sarcoma in polyostotic Paget's disease, and a very grim prognosis. Development of a neurological deficit in a patient with Paget's disease is an unusual occurrence which should suggest sarcomatous transformation. Roentgenographic changes are difficult to identify on plain films of the spine and consequently CT scan studies are warranted whenever a sarcoma is suspected.

The authors report a case of insufficiency fracture of the sacrum in an 81-year old woman. The fracture was related to disjunction of the pubic symphysis consecutive to curettage of the pubic bones for septic osteitis developed after vulvectomy for cancer. The diagnosis was suspected on the results of bone scintigraphy and was confirmed by computerized tomography with frontal sections and contrast inversion, showing the characteristic H-shaped fracture.