Radhesh K. Lalam

SAPHO: What radiologists should know

SAPHO (synovitis, acne, pustulosis, hyperostosis, and osteitis) is an umbrella acronym for inflammatory clinical conditions whose common denominator is aseptic osteoarticular involvement with characteristic skin lesions. It involves all ages, can involve any skeletal site, and has variable imaging appearances depending on the stage/age of the lesion and imaging method. It mimics important differentials including infection and neoplasia. Awareness of the imaging features, especially in the spine, facilitates early diagnosis, prevents repeated biopsies, and avoids unnecessary surgery, while initiating appropriate treatment.

The spine in Paget’s disease

Paget’s disease (PD) is a chronic metabolically active bone disease, characterized by a disturbance in bone modelling and remodelling due to an increase in osteoblastic and osteoclastic activity. The vertebra is the second most commonly affected site. This article reviews the various spinal pathomechanisms and osseous dynamics involved in producing the varied imaging appearances and their clinical relevance. Advanced imaging of osseous, articular and bone marrow manifestations of PD in all the vertebral components are presented. Pagetic changes often result in clinical symptoms including back pain, spinal stenosis and neural dysfunction. Various pathological complications due to PD involvement result in these clinical symptoms. Recognition of the imaging manifestations of spinal PD and the potential complications that cause the clinical symptoms enables accurate assessment of patients prior to appropriate management.

Role of MRI in hip fractures, including stress fractures, occult fractures, avulsion fractures

MR imaging plays a vital role in the diagnosis and management of hip fractures in all age groups, in a large spectrum of patient groups spanning the elderly and sporting population. It allows a confident exclusion of fracture, differentiation of bony from soft tissue injury and an early confident detection of fractures. There is a spectrum of MR findings which in part is dictated by the type and cause of the fracture which the radiologist needs to be familiar with. Judicious but prompt utilisation of MR in patients with suspected hip fractures has a positive therapeutic impact with healthcare cost benefits as well as social care benefits.

Angiomatoid fibrous histiocytoma of bone: A calcifying sclerosing variant mimicking osteosarcoma

Angiomatoid fibrous histiocytoma is a neoplasm of uncertain histogenesis, which most commonly arises in the subcutaneous tissue of the extremities of children and young adults. We report the first case of a calcifying sclerosing variant of this entity. This case arose in bone—a site where there has been just 1 previously published case of typical (nonsclerosing/mineralizing) angiomatoid fibrous histiocytoma. The patient presented with the classical paraneoplastic syndrome that can occur with this tumor type and, apart from the described extracellular matrical features, displayed typical histologic features. Due to the rarity of angiomatoid fibrous histiocytoma at this site and the presence of matrical sclerosis/mineralization, this case raised the important differential diagnosis of osteosarcoma, both histologically and radiologically. The diagnosis was confirmed by molecular analysis; fluorescence in situ hybridization for EWSR1 gene disruption, and reverse transcription-polymerase chain reaction using newly designed primers on both frozen and decalcified, paraffin-embedded tissue samples showing an EWSR1-ATF1 translocation. It is important to recognize that this relatively indolent tumor can arise in bone and that it can contain focally mineralized hyalinized sclerotic matrix to avoid making the serious misdiagnosis of high-grade osteosarcoma and administering aggressive systemic chemotherapeutic treatment.

Soft tissue tumors in adults: ESSR-approved guidelines for diagnostic imaging

Soft tissue sarcomas are rare, but early, accurate diagnosis with subsequent appropriate treatment is crucial for the clinical outcome. The ESSR guidelines are intended to help radiologists in their decision-making and support discussion among clinicians who deal with patients with suspected or proven soft tissue tumors. Potentially malignant lesions recognized by ultrasound should be referred for magnetic resonance imaging (MRI), which also serves as a preoperative local staging modality, with specific technical requirements and mandatory radiological report elements. Radiography may add information about matrix calcification and osseous involvement. Indeterminate lesions, or lesions in which therapy is dependent on histology results, should be biopsied. For biopsy, we strongly recommend referral to a specialist sarcoma center, where an interdisciplinary tumor group, with a specialized pathologist, radiologist, and the surgeon are involved. In sarcoma, a CT scan of the chest is mandatory. Additional staging modalities are entity-specific. There are no evidence-based recommendations for routine follow-up in surgically treated sarcomas. However, we would recommend regular follow-up with intervals dependent on tumor grade, for 10 years after the initial diagnosis.

Magnetic resonance imaging of appendicular musculoskeletal infection.

Appendicular skeletal infection includes osseous and extraosseous infections. Skeletal infection needs early diagnosis and appropriate management to prevent long-term morbidity. Magnetic resonance imaging is the best imaging modality to diagnose skeletal infection early in most circumstances. This article describes the role of magnetic resonance imaging in relation to the other available imaging modalities in the diagnosis of skeletal infection. Special circumstances such as diabetic foot, postoperative infection, and chronic recurrent multifocal osteomyelitis are discussed separately.

Magnetic Resonance Imaging of Spinal Infection

This article reviews the pathophysiology of spinal infection and its relevance for imaging. Magnetic resonance imaging (MRI) is the modality with by far the best sensitivity and specificity for spinal infection. The imaging appearances of spinal infection in MRI are outlined, and imaging techniques are discussed. The problems of clinical diagnosis are outlined. There is some emphasis on the MRI differentiation of pyogenic and nonpyogenic infection and on the differential diagnosis of spinal infection centered on the imaging presentation.

Uncovertebral joint injury in cervical facet dislocation: the headphones sign

The purpose of our study is to demonstrate the uncovertebral mal-alignment as a reliable indirect sign of cervical facet joint dislocation. We examined the uncovertebral axial plane alignment of 12 patients with unilateral and bilateral cervical facet joint dislocation (UCFJD and BCFJD, respectively), comparing its frequency to the reverse hamburger bun sign on CT and MR axial images. Of the seven cases with BCFJD, five clearly demonstrated the diagnostic reverse facet joint hamburger bun sign on CT and MR images, but in two cases this sign was not detectable. In the five cases with UCFJD, four demonstrated the reverse hamburger bun sign on both CT and MRI. In one case the reverse hamburger bun sign was not seen adequately with either image modality, but the facet dislocation was identified on sagittal imaging. The uncovertebral mal-alignment was detected in all 12 cases. Normally, the two components of the uncovertebral joint enjoy a concentric relationship that in the axial plane is reminiscent of the relationship of headphones with the wearer’s head. We name this appearance the ‘headphones’ sign. Radiologists should be aware of the headphones sign as a reliable indicator of facet joint dislocation on axial imaging used in the assessment of cervical spine injuries.

Migrating lumbar facet joint cysts

ObjectiveThe majority of lumbar facet joint cysts (LFJCs) are located in the spinal canal, on the medial aspect of the facet joint with characteristic diagnostic features. When they migrate away from the joint of origin, they cause diagnostic problems.Materials and methodsIn a 7-year period we examined by computed tomography (CT) and magnetic resonance (MR) imaging five unusual cases of facet joint cysts which migrated from the facet joint of origin.ResultsThree LFJCs were identified in the right S1 foramen, one in the right L5-S1 neural foramen and one in the left erector spinae and multifidus muscles between the levels of L2–L4 spinous process.ConclusionsAwareness that spinal lesions identified at MRI and CT could be due to migrating facet joint cyst requires a high level of suspicion. The identification of the appositional contact of the cyst and the facet joint needs to be actively sought in the presence of degenerative facet joints.

Sonoelastography in the musculoskeletal system: Current role and future directions

Ultrasound is an essential modality within musculoskeletal imaging, with the recent addition of elastography. The elastic properties of tissues are different from the acoustic impedance used to create B mode imaging and the flow properties used within Doppler imaging, hence elastography provides a different form of tissue assessment. The current role of ultrasound elastography in the musculoskeletal system will be reviewed, in particular with reference to muscles, tendons, ligaments, joints and soft tissue tumours. The different ultrasound elastography methods currently available will be described, in particular strain elastography and shear wave elastography. Future directions of ultrasound elastography in the musculoskeletal system will also be discussed.