Key points
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The fascial system is a continuum of connective tissues that can be involved in traumatic, infectious, and neoplastic disorders
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MRI is the best imaging technique to detect localized fascial involvement and assess its extent
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MRI may be limited in the characterization of localized fascial disorders
Introduction
Anatomy and terminology
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“Fascia superficialis” to designate the complex formed by the layer of connective tissue located immediately deep to the dermis (stratum membranosum) and its attachments to the dermis (retinacula cutis superficialis) and to the deeper components of the fascial system (retinacula cutis profondis)
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“Deep peripheral fascia” to designate the layer of connective tissue located at the interface between the hypodermis and the connective tissue surrounding the muscles (epimysium)
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“Deep intermuscular fascia” to describe the deep intermuscular septa located deep to the deep peripheral fascia and separating muscles and muscle groups from each other.
Traumatic disorders
Morel-Lavallée lesion
Myofascial and myotendinous injuries
Muscle hernia
Infectious diseases
Non-necrotizing and necrotizing cellulitis
Necrotizing fasciitis
Neoplastic diseases
Superficial fibromatosis
Desmoid tumors (deep fibromatosis)
Sarcomas
Recommendations to image localized diseases involving the fascial system at MRI
Conclusion
Diagnosis | Key MRI findings |
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Morel-Lavallée lesion | • Fusiform or ovoid fluid collection • Located at the interface between the hypodermic fat and the deep peripheral fascia |
Myofascial and myotendinous injuries | • Loss of the normal organization of the muscles and fasciae with abnormal heterogenous intermediate signal intensity • Inconstant collections of fluid and/or blood • Located at the interface between the muscle and the epimysium (myofascial injuries) and the interface between the muscle and the tendon (myotendinous injuries) |
Muscle hernia | • Focal bulging of the muscle tissue out of the muscle compartment into the hypodermic fat • Interruption of the deep peripheral fascia is inconstantly observed |
Non-necrotizing and necrotizing cellulitis | • Infiltration of the hypodermis with fluid-signal intensity and enhancement after contrast material injection • May be associated with collections and lack of enhancement of the hypodermis due to poor vascularization and/or necrosis (necrotizing cellulitis) |
Necrotizing fasciitis | • Thickening of the deep fasciae with high signal intensity on fluid-sensitive sequences and heterogeneous enhancement after contrast material injection • Low signal intensity areas visible on all sequences suggestive of gas (highly specific but not sensitive) • Extensive thickening of the intermuscular fasciae with an appearance suggesting incomplete vascularization supports the diagnosis |
Palmar fibromatosis | • Nodules in continuity with the palmar aponeurosis • Diagnosis is usually clinical |
Plantar fibromatosis | • Nodule in continuity with the plantar aponeurosis • May be multiple and bilateral |