Imaging approach to a patient with an acute swolen leg.

1. Imaging approach to a patient with an acute swolen leg.

7. DVT: Quick Facts • Clinical signs and symptoms of DVT are unreliable. • If clinical signs alone were used to diagnose DVT, 42% of patients would receive unnecessary anticoagulation therapy. • Most patients evaluated with US do not have DVT • In 60%–80% of symptomatic patients, a diagnostic test can rule out DVT . This means that approximately seven of 10 patients could have a cause other than DVT for pain, oedema, mass, or erythema in the legs. • Most patients who develop DVT are asymptomatic

8. dvt • Compression US remains the imaging procedure of choice for the investigation of patients with suspected DVT. • It is a highly sensitive and specific test for the diagnosis of proximal DVT in symptomatic patients. • Management approaches that rely on two negative compression US studies obtained 1 week apart have proved to help safely exclude the diagnosis of DVT. • Compression US is much less sensitive for diagnosing DVT following high-risk surgical procedures such as total hip or knee arthroplasty • In the United States, the annual combined incidence of DVT and pulmonary embolism is at least 70 per 100,000 individuals

9. dvt • Fewer than 10% of patients with DVT will have isolated iliofemoraldisease, and this syndrome tends to occur in certain well-recognized clinical situations. • Peripartum period (90% of cases, it will involve the left leg likely due to compression of the left common iliac vein by the right iliac artery during pregnancy. • Pelvic mass or recent pelvic surgery is typically found in the iliofemoralveins. • Oral contraceptive use. • Antiphospholipidantibody syndrome.

11. Anatomical approach • The anatomic approach is the most useful strategy for characterizing the spectrum of pathologic conditions seen in patients with symptoms that simulate DVT. • The inferior extremity can be divided into four regions—inguinal, thigh, popliteal, and lower leg • The differential diagnoses affecting the lower extremities include infectious, neoplastic, traumatic, inflammatory, vascular, and miscellaneous entities

12. Inguinal Region

13. Inguinal Region: Lymphangitis • Inflammation of the lymphatic vessels. • Usually seen with oedema, which can appear clinically similar to DVT. • US: The presence of adenopathiesand tubular dilatations that are superficial to the veins and that show no evidence of flow on colour Doppler. • MR can help further characterize lymphangitis

15. Inguinal Region: vascular lesions • The most common vascular pathologic conditions that simulate DVT are secondary to catheterization of the common femoral artery: • Hematomas • Pseudoaneurysms • Obese patients, large-bore sheaths, antiplatelet therapy, and postproceduralanticoagulation • ColorDoppler bidirectional flow, which appears as a “yin-yang” sign. • The dimensions of the neck should be measured to determine whether the best treatment is to use compression therapy or to administer a thrombin injection Less commonly from nonsurgical trauma

17. Inguinal Region: Fat related lesions • The symptoms of femoral hernias, especially incarcerated femoral hernias, which can produce a painful, bluish mass that is nonreducible, are similar to those of DVT  • Use of the Valsalvamanoeuvre and examining the patient in supine and standing positions are essential to diagnose a hernia and to rule out DVT . • Loss of peristalsis and a lack of mucosal blood flow can help determine if a hernia is incarcerated

18. Valsalva

19. Inguinal Region: Lipomas • Of the many fat-containing soft-tissue masses, lipoma is by far the most common mass seen in the subcutaneous tissue. • Lipomasare usually asymptomatic, but when they are large and closely related to the femoral structures, they can compress the vein or nerve and exhibit symptoms similar to those of DVT.

21. Thigh:

22. Thigh: Muscular lesions • The most frequent cause of muscular lesions is trauma. • Muscular lesions are subdivided into: • Contusions • Muscle strains • Tears • Lacerations

23. Thigh: Muscular lesions • Contusions: on rare occasions they may be confused with DVT. • Muscle strains, tears, and lacerations often mimic DVT. • Minor trauma: Muscular contusions with oedema in the focal lesion. • Major trauma: Hematomas. • Anechoic to echogenic in the first 24 hours. • In the following 2–3 days, it becomes hypoechoic or anechoic; • Thereafter, an increase in echogenicity can be seen

25. Thigh: Chronic Exertional Compartment Syndrome • Classified as either acute or chronic • The acute form of compartment syndrome is always related to trauma and therefore is not a differential diagnosis of DVT. • In chronic compartment syndrome, recurrent pain is caused by exercise; this is because of the increase in muscle mass that is associated with exercise. • Chronic exertional compartment syndrome primarily affects the infrapoplitealsegment of the extremity, but it can also be seen in the thigh. • On images, diagnostic clues include an increase in the size of the affected compartment and a diffuse increment of echogenicity. • However, because US and MR imaging findings are sometimes nonspecific, comparative exploration is useful in view of the subtlety of the findings

27. Thigh: myositis • Common cause of muscular edema: • Secondary to: • Autoimmune disease, infection, vasculitis, and trauma. • When the infection is in the thigh, myositis usually compromises the quadriceps. • A diffuse increase in the echogenicity of the affected muscle fibers is seen in the early stages of myositis and is associated with an increase in the diameter of the muscle group. • The natural evolution of the infection leads to formation of an abscess with central necrosis

29. Popliteal region

30. Popliteal region: Baker Cysts • Most common cystic lesions seen around the knee. • The medial gastrocnemius-semimembranosus bursa communicates with the knee joint in more than 50% of patients older than 50 years. • Symptoms usually arise from growth or rupture of the cyst. • Causes: • Usuallysecondary to degenerative changes of the knee. • Meniscal rupture • Synovitis • Chronic infectious processes • Inflammatory arthritis(RA)

33. Popliteal region: Popliteal Artery Aneurysms • True popliteal artery aneurysms are the most common type of peripheral artery aneurysms. • Transverse diameter of 7 mm or more . • Bilateral in 50%–70%. • 6% Rupture • Associated with aneurysms in other locations in 30%–50%. • 45% of popliteal artery aneurysms are asymptomatic. • Symptomatic when they rupture or compress the popliteal vein.

35. Lower Leg

36. Lower leg: Tennis Leg • Common injury • Middle-aged patients • Hyperextension of the knee and forced dorsiflexion of the ankle. • Usually associated with exercise, but it can also be caused by normal, daily activities. • Clinically • Sudden pain in the calf that patients describe as a “pop.” • Over the following 24 hours, oedema and pain ensue, symptoms that simulate DVT.

39. Lower leg: Miscellaneous Lesions • Most common: • Venous congestion (cardiac/ renal failure and fluid overload) • Cellulitis • Imaging findings: • Swelling of the subcutaneous tissue.

40. Musculoskeletal Infection: Role of CT in the Emergency Department • CT is invaluable for detecting deep complications of cellulitis and pinpointing the anatomic compartment that is involved by an infection. • CT is used to accurately differentiate between: • Superficial cellulitis and cellulitis associated with a deep-seated infection. • Although all patients with musculoskeletal infection will require treatment with antibiotics, CT helps guide therapy toward emergency surgical debridement in cases of necrotizing fasciitis and toward percutaneous treatment in cases of abscess formation • Clinical parameters(CRP,WCC,ESR)for the detection of musculoskeletal infection generally lack sensitivity and specificity

41. Musculoskeletal Infection: Role of CT in the Emergency Department • High risk group for serious and rapid spread of infection: • Diabetes, immunodeficiency, impaired peripheral circulation, or a history of lymphadenectomy • If the infection spreads to deeper tissues, deep cellulitis, myositis, necrotizing fasciitis, or osteomyelitis, abscess can occur, all of which can be excluded with CT

44. Necrotizing fasciatis • Morbidity and mortality rate is 70%–80% • One of the most important predictors of mortality is a delay in the diagnosis of necrosis. • Imaging findings in necrotizing fasciitis are similar to those in cellulitis but are more severe and show involvement of deeper structures. One specific distinguishing sign of necrotizing fasciitis is the presence of gas in the subcutaneous tissues. fluid collections along the deep fascial sheaths, and extension of edema into the inter-muscular septa and the muscles. • Contrast-enhanced CT, there is no demonstrable enhancement of the fascia, a finding that confirms the presence of necrosis and helps distinguish nonnecrotizing fasciitis from necrotizing fasciitis. • Nonnecrotizing fasciitis does not require emergency surgery, but affected patients should be followed up because of the potential for necrosis.

46. Primary pyomyositis • CTfindings • Enlargement of a muscle group that is disproportionate to the involvement of subcutaneous tissue helps distinguish myositis from primary cellulitis

48. Osteomyelitis • Young adults, it is most commonly associated with an open fracture or direct trauma. • Elderly and pediatricpatients, the cause of osteomyelitis is typically bacteremia. • Patients at high risk to develop osteomyelitis include: • Immunosuppression • Diabetes mellitus • Sickle cell disease • Intravenous drug abuse • Alcoholism.

50. Osteomyelitis: Role of imaging • Diagnosis requires two of the following four criteria, one of which is positive imaging findings: (a) purulent material draining from the site of acute osteomyelitis,(b) positive findings at bone tissue or blood culture, (c) localized classic physical findings of bone tenderness and edema, and, as mentioned, (d) positive radiologic findings. • Conventional xraysof acute osteomyelitis is insufficient because bone changes are not evident for 14–21 days after the onset of infection. • Xrays are typically normal at presentation in 95% of cases, and it is not until 28 days after the onset of infection that 90% of patients demonstrate some abnormality at conventional radiography . • MRI is the accepted modality of choice for the early detection and surgical localization of osteomyelitis. • In the emergency department, CT is usually more readily available for establishing the diagnosis