[Special aspects of stress fractures]. / Spezielle Aspekte bei Stressfrakturen.

BACKGROUND: Stress fractures are very common in clinical practice. They can be classified into fatigue fractures that affect healthy bone and insufficiency fractures in which the bone is already damaged or weakened. IMAGING MODALITIES: Conventional x­ray images are the standard method in case of a suspected stress fracture. If x­rays are negative, magnetic resonance imaging (MRI) can be performed, which has a significantly higher sensitivity and can provide further information such as evidence for a pathological fracture. Computed tomography (CT) is suitable for an exact representation of the course of the fracture line and thus for preoperative planning. As a nuclear medicine procedure, bone scintigraphy can be used as bone metabolism in the area of a fracture is increased. KEY IMAGING FINDINGS: Typical x­ray signs are the gray cortex sign, the periosteal reaction and a fracture line that is often oriented perpendicular to the cortex and which shows a parallel sclerotic line. Later on, callus material becomes evident. MRI reveals periosteal and medullary edema, a reaction in the surrounding soft tissue and a T1-hypointense fracture line. In CT, the fracture line is hypodense and often associated with an adjacent sclerotic area. CONCLUSIONS: For a correct diagnosis, it is important to be familiar with the appropriate imaging modalities and the respective imaging findings of stress fractures. If initial x­rays are normal and symptoms persist, an MRI should be performed. This is also to rule out other causes such as a pathological fracture.

[Bone tumors and metastases: tips for initial diagnosis and follow-up : Update 2019]. / Knochentumoren und -metastasen: Tipps für Erstdiagnose und Nachsorge : Update 2019.

Benign bone tumors are frequently discovered as incidental findings, whereas malignant tumors and metastases often become clinically noticeable due to pain or swelling. The initial radiological diagnostics by conventional X­ray imaging, magnetic resonance imaging (MRI) and computed tomography (CT) play an important role in the assessment of dignity and further treatment planning. The aftercare of bone tumors is necessary for the recognition of recurrences and distant metastases as well as the detection of complications, e.g. after implantation of a prosthesis. Implanted metal and posttherapeutic alterations can impede the aftercare due to artifacts and treatment-associated tissue alterations. In addition to the recommendations of the Association of the Scientific Medical Societies in Germany (AWMF), the European Organisation for Research and Treatment of Cancer (EORTC) and the European Society of Musculoskeletal Radiology (ESSR), study protocols can be used as orientation for the aftercare of individual primary malignant bone tumors.

Imaging of hip and thigh muscle injury: a pictorial review.

Muscle injuries of the hip and thigh are a highly relevant issue in competitive sports imaging. The gold standard in diagnostic imaging of muscle injuries is magnetic resonance imaging (MRI). Radiologists need to be familiar with typical MRI findings in order to accurately detect and classify muscle injuries. Proper interpretation of the findings is crucial, especially in elite athletes. In soccer players, muscle injuries of the hip and thigh are the most common reason for missing a game.The present pictorial review deals with the diagnostic assessment, especially MRI, of muscle injuries of the hip and thigh. Typical MR findings in muscle injuries include edema, hematoma, and tendinous avulsion as well as partial or complete muscle tear. To estimate the time to return to play, a grading into three groups-muscle strain, partial tear, complete tear-has traditionally been used. Taking into account the most recent literature, there are other prognostic factors such as the longitudinal length of a tear, the tendon's intramuscular component, or persisting edema.