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Abstract
Popliteal fossa lesions are divided into fluid containing lesions, solid lesions not connected to bone, and solid lesions connected to bone:
Imaging of soft tissue lesions begin with plain radiography, although it is of limited value. Its value lies in determining that soft tissue closely opposed to bone has its origin in soft tissue and not bone and showing calcification as in calcified aneurysm. Ultrasound can be useful for assessment of soft tissue masses. It can be a reliable alternative to other more costly imaging technique such as MRI but because of its small field of view, traditional sonography is limited in its capability to image lesions involving large anatomic segments. Sonography can determine if a mass is cystic or solid. Simple cystic lesions can be consider benign. Imaging characteristics of solid and complex cystic lesions are generally nonspecific. Sonography has a limited role in evaluation of osseous lesions, then CT is used to asses the infiltration and extent of the lesion. MR imaging is the preferred modality for the evaluation of a soft tissue masses. It provides excellent discrimination between normal and abnormal tissues. The high specificity and negative predictive value that can be achieved with MR imaging for tissue characterization whether benign or malignant depend on the prevalence of benign lesions among soft tissue by other radiologic appearance, so MR imaging is not reliable for distinguishing benign from malignant when imaging appearance is nonspecific, knowledge of lesion location, age, clinical history is used to establish an ordered differential diagnosis and these lesions need biopsy.
Duplex US and color flow mapping(angiosonography) is the initial imaging technique for demonstrating arteries and veins, followed by CT angiography and MR angiography which provide the same information as angiography regarding the vessel wall, presence and extent of the lesion and consider non invasive, quick, repeatable and allow a survey of the whole lower limb vessels. Angiography can be done for preoperative planning as it is an invasive method.