Ultrasound evaluation of clinical mimics of deep vein thrombosis: essential insights for radiologists in interpretation
Article information
Abstract
Ultrasonography (US) is a sensitive and radiation-free technique for diagnosing deep vein thrombosis (DVT). Therefore, when DVT is clinically suspected but not detected on US, radiologists should consider a range of alternative differential diagnoses. This review article presents the imaging findings of clinical conditions that mimic DVT, which can be distinguished using a multimodal radiologic approach. Additionally, DVT mimics can be categorized into two groups based on whether a flat or normal waveform is observed on Doppler US. This article details the imaging findings and clinical presentations of DVT mimics, organized by these classifications. This information may help radiologists make more accurate diagnoses, enabling patients to receive appropriate treatment in a timely manner.
Introduction
Deep vein thrombosis (DVT) is a condition characterized by the formation of blood clots in the deep veins, typically in the veins of the upper and lower extremities [1]. Symptoms can range from being asymptomatic to exhibiting non-specific signs such as swelling, redness, pain, tenderness, and changes in skin color. In severe cases, DVT can lead to arrest due to massive pulmonary thromboembolism and subsequent collapse of the right ventricle. Doppler ultrasonography (US) and computed tomography (CT) venography are commonly used to diagnose DVT. Given that the symptoms of DVT are often non-specific, it can be clinically mistaken for other conditions. Therefore, accurate diagnosis is essential not only for appropriate treatment but also for preventing complications, including anticoagulation-related bleeding [2].
The veins of the lower extremity form a continuous network, and DVT can develop in any segment. It is crucial to thoroughly evaluate the entire venous system from the common iliac veins to the peripheral veins using grayscale US and Doppler waveform analysis. In accordance with the guidelines from the Korea Society of Ultrasound in Medicine, Doppler waveform analysis was conducted on the common femoral vein, popliteal vein, great saphenous vein, and small saphenous vein. Diseases that mimic DVT were classified into two categories based on their waveform characteristics, as shown in Fig. 1. For patients for whom US is not feasible, or in emergency situations, further assessment using CT or other imaging techniques was considered necessary. The first category includes cases that display a flat waveform due to venous stasis, typically occurring when vessels are externally compressed. This can be seen in conditions such as pelvic malignancy, pregnancy, and lymphocele. The second category presents a normal waveform, which is further divided into either abnormal focal lesions or diffuse lesions, as identified through CT venography. Focal lesions may include vascular tumors, aneurysms, and Baker's cysts, whereas diffuse lesions are found in conditions like lymphedema and cellulitis.
Diagnostic algorithm of clinically suspected deep vein thrombosis (DVT).
The algorithm displays duplex Doppler ultrasonography findings for patients clinically suspected of having DVT. It categorizes true DVT and DVT mimics according to the different waveform patterns observed in Doppler ultrasonography (US). Normal venous waveforms may be associated with conditions such as popliteal artery diseases, Baker's cyst, hematomas, lymphedema, myositis, and tumors. Venous stasis, characterized by a flat waveform, may be indicative of pelvic malignancy, pregnancy, May-Thurner syndrome, inferior vena cava (IVC) obstruction or agenesis, and thrombotic occlusion of venous stents.
The classification of a patient's swollen leg as either inflammatory/infectious or non-inflammatory is determined by their clinical history, laboratory results, and physical examination. Inflammatory/infectious conditions encompass cellulitis, myositis, abscess, and necrotizing fasciitis, while non-inflammatory conditions include popliteal artery disease, Baker's cyst, and tumors. Although treatment approaches vary between these categories, this paper focuses on classifying conditions based on imaging findings
Although numerous clinical papers on DVT mimics have been published, review articles that focus on radiologic findings remain rare. Diagnostic approaches frequently rely on radiological examinations when there is clinical suspicion of DVT, highlighting the importance of recognizing conditions that present with similar features. Consequently, this article aims to illustrate the imaging findings of DVT and various conditions that mimic it, as well as their associated clinical symptoms.
Imaging Features of Deep Vein Thrombosis
DVT is characterized on US by the presence of heterogeneous echogenic materials filling the deep veins, indicative of thrombus formation. On Doppler US, a decrease or absence of venous flow in the Doppler waveform patterns may further support a DVT diagnosis. One of the US findings indicative of DVT is decreased compressibility of the affected vessel [3]. Normally, vessels should flatten when compressed under a US probe. However, in veins affected by DVT, the thrombus may prevent compression. While some cases of DVT involve the entire lumen and maintain a round shape under compression (Fig. 2), partial DVT may cause the veins to deform but still include non-compressible areas where the thrombus is present.
Deep vein thrombosis (DVT) in a 78-year-old woman with right leg pain and edema.
A. Ultrasonography (US) of the right popliteal vein without compression under the US probe are shown. There are heterogeneous echogenic materials in the lumen of the right popliteal vein. Normally, the vein should be completely collapsed after compression. B. US of the right popliteal vein with compression under the US probe are shown. Even under compression, the lumen of the vein maintains a round shape. These findings suggest an acute DVT. C. On Doppler US, there is no color flow in the right popliteal vein. D. Computed tomography venography shows filling defects of contrast material at the right popliteal vein with surrounding soft tissue infiltration. A, right popliteal artery; V, right popliteal vein.
Differential Diagnosis Group I: Flat Waveform on Doppler Ultrasonography—Venous Stasis Induced by Extrinsic Compression (Pelvic Malignancy, Pregnancy, Lymphocele)
Pelvic Malignancy, Pregnancy, Lymphocele
Extrinsic compression occurs when external pressure is applied to blood vessels, such as the iliac vein, potentially disrupting blood flow. This condition can manifest symptoms that closely resemble those of DVT, including swelling, pain, and changes in skin color. As a result, both careful clinical evaluation and imaging studies are essential to distinguish between DVT and extrinsic compression. Various conditions can cause extrinsic compression in the lower extremities, including pelvic malignancies (Fig. 3), pregnancy (Fig. 4), and lymphocele (Fig. 5).
Venous stasis due to pelvic malignancy in a 40-year-old woman with left leg pain and edema for 2 days.
A. The left common iliac vein is compressed due to an ovarian mass (arrow). The masses were removed with salphingo-oophorectomy and pathologically confirmed as metastatic adenocarcinoma from colonic origin. No deep vein thrombosis is found on ultrasonography. B. Computed tomography venography shows an approximately 14-cm solid and heterogeneously enhancing mass (white asterisk) arising from the right ovary and an approximately 15-cm multiloculated cystic and solid mass (black asterisk) arising from the left ovary. The left common iliac vein (arrow) is compressed by the mass. A, left external iliac artery; V, left external iliac vein.
Venous stasis due to pregnancy in a 29-year-old woman (gestational age 34+5 weeks) with left foot pain and severe edema.
A, B. There is no definite evidence of thrombus in both leg veins, including the right common femoral vein and left popliteal vein. However, flat waveforms are noted, suggesting upstream compression due to pregnancy. Furthermore, the echogenicity of the patient’s vein is only slightly increased, which may reflect red blood cell aggregation due to venous stasis.
Venous stasis due to lymphocele after radical hysterectomy and lymph node dissection for diffuse large B-cell lymphoma in a 59-year-old woman with right calf pain and edema.
A. The right external iliac vein is compressed due to a hypoechoic lobulated mass, suspected to be lymphoceles (white and black asterisks). Ultasonography (US) shows absent flow of the right external iliac vein (V) while a triphasic Doppler waveform is maintained in the common iliac vein (not shown). B. Causative upstream stenosis (white arrow) is noted due to lymphoceles (white and black asterisks). No deep vein thrombosis is found on US. C. Subsequent computed tomography showed that fluid collections along the lymph node dissection site, suggesting postoperative lymphocele (white asterisk). A, external iliac artery; V, external iliac vein.
Common pelvic malignancies that may cause compression of the iliac veins include gynecologic malignancies or Krukenberg tumors. This compression can lead to swelling in the affected lower extremity [4].
Pregnancy can alter the positioning of abdominal organs and lead to the compression of vessels, causing swelling in the lower extremities. Additionally, during a normal pregnancy, clotting factors such as fibrinogen, VII, VIII, von Willebrand factor, IX, X, and XII are elevated, creating a hypercoagulable state. For these reasons, pregnancy is recognized as a risk factor for DVT [5,6]. It is crucial to differentiate between pregnancy or pelvic malignancy and DVT through a thorough evaluation, which includes a detailed medical history and laboratory findings. Furthermore, based on clinical suspicion, additional imaging studies such as US, non-contrast magnetic resonance imaging (MRI), or pelvic CT are recommended.
Lymphocele is a fluid-filled sac that forms in the body due to the accumulation of lymphatic fluid. This condition often occurs after surgical procedures involving lymph node dissection or trauma to lymphatic vessels. On US, a lymphocele typically appears as a unilocular cyst with anechoic contents, and it may include septations, debris, and a thin-walled capsule. Importantly, it shows no blood flow on Doppler imaging [7]. The differential diagnosis involves thorough history taking and the identification of potential causes such as malignancy, pregnancy, trauma, or surgery. Depending on the severity of extrinsic compression, US may reveal a narrowed vessel exhibiting weak or absent flow, which may or may not include a thrombus. Contrast-enhanced abdominopelvic CT is a valuable tool for identifying features associated with extrinsic factors, such as masses or lesions that compress blood vessels.
May-Thurner Syndrome
May-Thurner syndrome is a vascular condition characterized by the compression of the left common iliac vein by the overlying right common iliac artery and lumbar vertebrae. In cases of May-Thurner syndrome, collateral vessels may also be present. This anatomical compression can lead to severe swelling, pain, venous stasis, and an increased risk of DVT in the veins of the left lower extremity.
On US, May-Thurner syndrome is characterized by thick, echogenic walls and a reduced caliber of the left common iliac vein [8]. Additionally, if collateral vessels are present in the left lower extremity, continuous flow can be observed in the left common iliac vein distal to the compression site. Chronic DVT may also be present in the left external iliac vein. However, the evaluation of the internal iliac vessel using US is limited due to overlying bowel gas and its deep location; therefore, alternative diagnostic tools such as CT are recommended. CT imaging serves as an effective modality for evaluating May-Thurner syndrome (Fig. 6).
May-Thurner syndrome in a 78-year-old woman with left foot edema.
A. The left common iliac vein (arrow) is compressed by the left common iliac artery, without definite evidence of thrombus formation. B. Absent color flow of the left common iliac vein is noted on Doppler ultrasonography, suggesting the possibility of May-Thurner syndrome.
Obstruction or Agenesis of the Inferior Vena Cava
Agenesis of the inferior vena cava (IVC) is a very rare congenital anomaly that typically results from a developmental failure of the venous systems during embryogenesis, such as intrauterine or perinatal thrombosis of the IVC [9]. The absence of the IVC may lead to venous insufficiency in the lower limbs, particularly in early adulthood. This condition causes blood stasis and the formation of collateral pathways. On US, both legs display a flat and uniform Doppler wave pattern. CT imaging reveals the absence of the IVC and shows various collateral vessels, including the azygos-hemiazygos system and paraspinal circulation (Fig. 7).
Chronic inferior vena cava (IVC) obstruction in a 28-year-old man with left leg edema, dorsal foot color change, pretibial wound, and chronic lower extremity swelling.
A. Flat uniform Doppler waveform in both femoral veins suggests obstruction proximal to the ultrasonography exam site. B. On computed tomography imaging, the the IVC is not visualized, and marked collateral vessels (arrows) are observed. There are other collateral vessels at the bilateral lower extremities, inguinal, iliac and abdominal wall area, suggesting chronic stenosis or obstruction of IVC (not on this figure).
In-stent Restenosis of Iliac Venous Stent
The use of venous stenting to treat various venous disorders has seen a significant increase in recent years. Although venous stenting is recognized as an effective treatment for symptomatic venous obstruction, in-stent restenosis remains the most frequent and clinically significant complication following the procedure. Most cases of stent occlusion occur within six months of the initial stenting [10,11]. If stent occlusion arises, the signs and symptoms of venous disease can be expected to recur. Both US and CT scans can detect in-stent thrombosis, which is characterized by a filling defect (Fig. 8). Consequently, it is essential to conduct imaging studies in symptomatic patients with venous stents to assess their condition.
Thrombotic occlusion of a venous stent in a 66-year-old woman with right ankle pain.
A. Doppler ultrasonography shows a stent which inserted in the right external iliac vein without color flow (asterisk). B. Computed tomography venography reveals a total thrombotic occlusion of the right external iliac venous stent (arrow).
Differential Diagnosis Group II: Normal Waveform on Doppler Ultrasonography
Lymphedema
Non-inflammatory subcutaneous edema can arise from a variety of causes, including lymphatic obstruction, systemic conditions, or venous insufficiency [12]. Lymphedema, a specific type of non-inflammatory subcutaneous edema, results from the accumulation of lymphatic fluids. It is categorized into primary and secondary lymphedema. Primary lymphedema is typically due to congenital genetic factors, whereas secondary lymphedema develops from damage to lymph nodes or vessels caused by other conditions or external factors such as neoplasms, surgery, and radiation therapy. This is particularly common following radical lymph node dissection during gynecological surgeries. Lymphoscintigraphy is regarded as the gold standard for diagnosing lymphedema [13].
On lymphoscintigrams, lymphedema is characterized by a variety of findings, including disrupted lymphatic flow, collateral lymph vessels, dermal backflow, delayed or absent flow, reduced lymph nodes, dilated lymphatics, and in severe cases, complete non-visualization of the lymphatic system [14]. US and CT are also effective imaging modalities that play an essential role in the evaluation and monitoring of lymphatic irregularities. In US imaging, lymphedema appears as linear anechoic bands within the deep subcutaneous layer, which indicate the presence and extent of lymphatic abnormalities (Fig. 9) [15]. Additionally, patients with lymphedema experience resistance to venous return, further exacerbating the edema [16].
Lymphedema due to malignant melanoma in a 79-year-old man with bilateral leg edema, with no deep vein thrombosis on ultrasonography (US).
A. Computed tomography (CT) venography shows diffuse subcutaneous edema in both lower extremities (arrowheads). B. US demonstrates interstitial edema in both calves (arrows), consistent with findings on CT venography, suggesting lymphedema.
Cellulitis
Cellulitis is a common bacterial infection primarily affecting the subcutaneous tissue layer and hypodermis, without extending to the muscle or deep fascia [11]. Clinically, cellulitis is characterized by increased skin temperature, redness, a peau d'orange appearance, and regional lymphadenopathy. While most cases can be distinguished based on these symptoms, early cellulitis, presenting with mild pain, swelling, and redness, may need to be differentiated from DVT. On US, cellulitis is indicated by abnormal echogenicity and thickening of the dermis layer, as well as subcutaneous tissue edema and hypoechoic stranding between the echogenic fat lobules, a pattern often described as cobblestone (Fig. 10) [11]. However, in some instances, cellulitis and DVT may coexist.
Cellulitis in a 60-year-old man with right calf pain and redness, with no deep vein thrombosis on ultrasonography (US).
A. US shows subcutaneous tissue edema and hypoechoic stranding between the echogenic fat lobules (arrows), a pattern often described as cobblestone. B. Doppler US reveals increased color flow at the subcutaneous layer of the calf (arrowheads), suggesting cellulitis.
Myositis
Myositis is an inflammatory condition that affects skeletal muscles, characterized by muscle weakness, pain, and surrounding inflammation. This condition can arise from various etiologies, including autoimmune factors, infections, or drug-related causes. Timely diagnosis and appropriate management are crucial for alleviating symptoms and preventing complications.
US findings of myositis typically reveal increased echogenicity within the affected muscles [17]. Additionally, fascial thickening and abnormal vascular flow may be observed. US provides real-time imaging of muscle structure and vascularity, assisting in accurate diagnosis and management [18]. On contrast-enhanced CT, the affected muscle usually exhibits edema and enhancement [19]. On MRI, myositis is characterized by T2 high signal alteration and enhancement in the affected muscles, accompanied by diffuse subcutaneous swelling and fatty infiltration (Fig. 11).
Myositis in a 75-year-old woman with bilateral leg pain and edema, with no deep vein thrombosis.
A, B. On Doppler ultrasonography, diffusely increased echogenicity (arrows) and vascularity of the vastus muscles are observed. C, D. Bilateral symmetric muscle signal alteration and enhancement of the lower extremity muscles are noted on magnetic resonance imaging. Diffuse subcutaneous swelling and fatty infiltration are also noted.
Abscesses
The etiology of abscesses involves underlying conditions, trauma, or the spread of infection from adjacent structures. Abscesses that occur in the lower extremities are localized collections of pus resulting from bacterial infections. These infectious lesions typically involve deep tissues and often present as swollen, painful masses. Clinically, redness, warmth, and tenderness are characteristic features.
On US, well-formed abscesses typically display characteristics such as a homogeneously anechoic mass, a complex mass with anechoic components, or a mass containing gas [20]. CT findings indicative of an abscess include abnormal fluid collections with peripheral rim enhancement, irregular wall thickening, and possible internal air bubbles [18]. Additionally, surrounding inflammatory changes, such as soft tissue edema and fat stranding, are commonly observed (Fig. 12). Markedly elevated inflammatory markers, including leukocyte count, C-reactive protein, and erythrocyte sedimentation rate, are distinguishing factors for DVT.
Intramuscular abscesses in a 70-year-old woman with right lower leg swelling.
Computed tomography venography shows an approximately 6.9×8.0×12.4 cm low-density lesion with peripheral rim enhancement in the posteromedial aspect of the right calf, in the medial gastrocnemius muscle (asterisk). Another 3.5×3.4×12.1 cm low-density lesion is seen in the anterior aspect of the right calf, in the tibialis anterior muscle (arrow).
Necrotizing Fasciitis
Necrotizing fasciitis is characterized by rapidly progressing severe inflammation and tissue destruction. It is commonly linked to trauma, open wounds, or surgical sites. The clinical manifestations of necrotizing fasciitis include intense pain, swelling, redness, and a rapidly spreading skin rash or discoloration. Systemic symptoms such as fever, chills, and malaise are also frequent [12]. Early diagnosis is critical, and it may need to be distinguished from DVT in the initial stages. Immediate medical intervention is essential due to the aggressive and life-threatening nature of the condition. On US, necrotizing fasciitis appears as edematous thickening of the fascial layer with gases or fluid collections within the affected area. CT is an effective modality for evaluating necrotizing fasciitis. Similar to US, CT imaging reveals the presence of gas within fluid collections tracking along fascial planes, asymmetrical fascial thickening associated with fat stranding, and edema extending into the intermuscular septa and muscle (Fig. 13) [11].
Necrotizing fasciitis in a 45-year-old woman with left thigh pain and edema.
A, B. Computed tomography venography shows free air within the fascia with diffuse muscle swelling from the left side of the thigh to the distal lower leg (arrows), suggesting necrotizing fasciitis. This patient also had bilateral acute pyelonephritis with left perirenal abscess (not on this figure).
Rhabdomyolysis
Rhabdomyolysis is a medical condition characterized by the rapid breakdown of skeletal muscle tissue, which results in the release of muscle cell contents into the bloodstream. Common causes of rhabdomyolysis include traumatic injuries, intense physical activity, certain medications, infections, and metabolic disorders. Diagnosis typically relies on laboratory findings, such as elevated levels of myoglobin and creatine kinase, which can lead to systemic complications.
On US imaging, rhabdomyolysis may present with decreased echogenicity of the muscles, increased thickness of the muscle fascia, and the presence of intramuscular hyperechoic areas. Additionally, edema may lead to reduced blood flow as observed in Doppler studies, although the flow in the femoral or popliteal arteries and veins remains unaffected. These characteristics can help differentiate it from DVT [21]. On CT imaging, heterogeneously hypodense muscles with enlargement are typical findings of rhabdomyolysis [22]. Additionally, peripheral enhancement of infarcted or necrotic tissue indicates muscular damage (Fig. 14).
Rhabdomyolysis in a 42-year-old man with bilateral leg edema, pruritus, oozing, and a creatine kinase level of 5,446 IU/L.
A, B. Diffuse swelling of the left obturator and adductor muscles (asterisks) with internal heterogeneously low attenuated lesions (arrows) are noted on computed tomography venography, accompanied by diffuse swelling of the left buttock and thigh, suggesting rhabdomyolysis.
Intramuscular Hematoma
Intramuscular hematomas generally result from trauma or injury to the muscle, causing bleeding within the muscle tissue [23,24]. Typical symptoms are localized pain, swelling, tenderness, and skin discoloration over the impacted area. Occasionally, an intramuscular hematoma may resemble DVT. Depending on the hematoma’s severity, it can also lead to restricted muscle movement and weakness. On US, an intramuscular hematoma appears as a hypoechoic or heterogeneous mass-like lesion without internal microvascular flow (Fig. 15) [25].
Intramuscular hematoma in a 61-year-old man with left calf pain, edema, and multifocal ecchymoses after COVID-19 vaccination.
A. On Doppler US, an approximately 4.7 cm hypoechoic lesion in the medial aspect of the left knee is noted (asterisk). The patient reported the greatest pain when this area was compressed. B. There is no definite evidence of thrombus or internal microvascular flow. This lesion (asterisk) was suggested to be an intramuscular hematoma in the medial head of the gastrocnemius head.
Baker’s Cyst with Complication
A Baker’s cyst is a fluid distension of the gastrocnemio-semimembranosus bursa that communicates with the knee joint [15,26]. An uncomplicated Baker’s cyst is typically asymptomatic and does not require treatment. However, Baker’s cysts complicated by infection or rupture may present with unilateral limb swelling, pain, and redness (Fig. 16). Painful cysts can be managed with injections and needle aspiration.
Non-ruptured Baker’s cyst in a 72-year-old man with left leg pain, edema and ecchymoses after coronavirus disease 2019 vaccination.
On Doppler ultrasonography, an approximately 1.3×3.3 cm anechoic lesion (asterisk) on the posteromedial side of the left knee is noted, suggesting a Baker’s cyst.
If a Baker's cyst ruptures, patients typically report sudden-onset calf pain, which may be accompanied by swelling and redness in the calf area. When the fluid from a cyst leaks into the popliteal fossa, fascial planes, and surrounding areas of the hamstring and medial gastrocnemius muscles, soft tissue edema can develop [27]. Clinically, the sudden onset of leg pain raises suspicions of a ruptured Baker’s cyst, DVT, or an acute hematoma. The Homans sign, which is pain in the calf region upon dorsiflexion of the foot, can be indicative of a ruptured Baker’s cyst. The detection of fluid accumulation in the intermuscular space suggests a ruptured Baker's cyst (Fig. 17) [27]. The US findings of a ruptured Baker’s cyst include the presence of anechoic or hypoechoic lesions surrounding the mass or cyst, as well as intra-cystic intra-articular bodies [28]. However, MRI provides better diagnostic accuracy than US. Additionally, Baker's cysts are typically located deeper or more medially compared to the popliteal vessels. Doppler studies can also be useful.
Ruptured a Baker’s cyst in an 86-year-old man with left leg edema.
A. A suspicious collapsed rim-enhancing lesion in the left popliteal fossa is noted on computed tomography (CT) venography (arrow). B. CT venography shows a diffuse fluids in the left lower leg intramuscular plane (arrows) and diffuse subcutaneous swelling, suggesting rupture of a Baker’s cyst.
Tumors (Vascular Tumor/Soft Tissue Tumor)
Tumors of the lower extremity are rare and are generally easy to distinguish from DVT. Common benign tumors in the lower extremity include hemangiomas, lipomas, and fibrous histiocytoma [29,30]. Intramuscular hemangiomas, which are benign soft tissue tumors, are typically found in the thigh and calf regions. The main symptoms are chronic pain and the presence of a new palpable mass. On US, intramuscular hemangiomas display varying echogenicity. In Doppler studies, they sometimes exhibit pulsatile arterial waveforms (Fig. 18). Due to their vascular component and fat content, intramuscular hemangiomas usually appear hyperintense on T2-weighted MRI and range from iso- to hyperintense on T1-weighted MRI.
Vascular tumor in a 68-year-old man with leg pain and edema for years.
A. On computed tomography (CT) venography, an approximately 1.2 cm bright enhancing lesion in the posteromedial aspect of left calf is noted (arrow). B. An approximately 1.2 cm well-defined soft tissue mass (asterisk) in the medial head of left gastrocnemius muscle is noted on US, correlating with the enhancing lesion on CT. C. This hypervascular mass encases a small muscular branch vein (arrowheads). The vascular tumor was suggested to be a hemangioma (asterisk).
Malignant soft tissue tumors, such as sarcomas in the lower extremity, are extremely rare and their incidence increases with age. These tumors typically present as a swelling and a palpable mass. The tumor may appear as a solid mass-like lesion, which may or may not include a cystic component (Fig. 19) [15]. Further evaluation with contrast-enhanced MRI is necessary.
Soft tissue tumor in a 68-year-old man with left leg claudication.
A, B. An approximately 4.1 × 6.8 cm well-defined heterogeneously enhancing mass (arrows) is located at the lateral side of left lateral femoral condyle extending to the lateral popliteal fossa. This patient underwent enhanced magentic resonance imaging that suggested soft tissue sarcoma (not on this figure).
Diseases of the Popliteal Artery
Representative diseases of the popliteal artery include popliteal artery aneurysm, popliteal artery entrapment syndrome, and cystic adventitial disease of the popliteal artery. A thrombosed popliteal artery aneurysm or other related diseases can compromise popliteal artery flow, potentially resulting in unilateral pain, claudication, and changes in skin color.
Popliteal artery aneurysms are the most common type of peripheral artery aneurysm [31]. Duplex US is the ideal imaging modality for screening and diagnosing these aneurysms, as it helps detect the aneurysm and evaluate its diameter. This modality provides detailed information about vessel patency, the development of mural thrombus, and the status of outflow vessels. On Duplex US, a thrombosed popliteal artery aneurysm is identified when it exhibits more than 50% of the normal diameter, which typically ranges from 0.7 to 1.1 cm [15]. Mural thrombi appear as hypoechoic lesions attached to the wall of the popliteal artery (Fig. 20). Additionally, an aneurysm shows communication with an adjacent artery, whereas DVT communicates with a vein. CT angiography and maximum intensity projection images also accurately measure the true lumen diameter and delineate the popliteal artery aneurysm [32].
Popliteal thrombosed aneurysm in a 74-year-old woman with left leg pain and edema for 2 days.
A, B. Doppler ultrasonography shows a partially thrombosed 1.6 cm aneurysm (asterisk) of the left popliteal artery. C. This thrombus is causing moderate stenosis of left superficial femoral vein, with a resistance index of 1.0.
Popliteal artery entrapment syndrome occurs when the popliteal artery is compressed due to abnormal embryologic development of surrounding structures, such as the medial head of the gastrocnemius muscle. This compression reduces blood flow to the lower leg and foot, leading to symptoms including calf claudication, pain, numbness, and weakness during plantar flexion and dorsiflexion of the feet. If left untreated, this condition can lead to serious complications such as arterial thrombosis or aneurysm formation (Fig. 21) [33]. On US, popliteal artery entrapment syndrome is characterized by arterial compression that is exacerbated by movements like plantar or dorsiflexion. MRI and CT are effective modalities for assessing the anatomic type of popliteal artery entrapment, identifying features such as an atypical course of the popliteal artery or unusual muscular insertions (Fig. 21).
Popliteal thrombosed aneurysm in a 74-year-old woman with left leg pain and edema for 2 days (same patient as in Fig. 20).
A. There is a normal relationship between the right popliteal vessels and the medial head of gastrocnemius muscle (arrowheads). B. An abnormal insertion of the left medial head of the gastrocnemius muscle between the popliteal artery and vein is observed, indicating popliteal artery entrapment syndrome, type II (arrow). C. It causes severe stenosis at the transitional area of the left popliteal artery.
Popliteal cystic adventitial disease is a rare condition, occurring in approximately 1 in 1,200 cases of claudication [34]. This disease involves cystic degeneration of the adventitial layer of the popliteal artery, often leading to compression and obstruction of blood flow. The clinical symptoms include intermittent claudication, leg pain, and, in severe cases, acute limb ischemia. On US, popliteal cystic adventitial disease appears as anechoic or hypoechoic masses originating from the arterial wall, typically presenting as multilobulated masses composed of multiple smaller cysts [35]. Doppler US is useful for assessing the extent of associated arterial stenosis or complete occlusion (Fig. 22).
Cystic adventitial disease of the popliteal artery in an 83-year-old man.
A, B. On Doppler ultrasonography, an approximately 2.7 cm anechoic lesion (arrow) without color flow at the left popliteal artery is noted. C, D. This lesion shows bright high signal intensity on T2-weighted magnetic resonance imaging, suggesting a cystic lesion. Furthermore, it arises from the popliteal artery wall (arrow), suggesting cystic adventitial disease.
Conclusion
There are numerous clinical conditions that mimic DVT, and it is crucial for radiologists to make accurate diagnoses based on a comprehensive understanding of the imaging findings associated with DVT and its mimics. The mimics of DVT have been categorized into two groups based on waveform analysis. Ultrasound serves as a valuable, cost-effective, and non-invasive method for differentiating between DVT and its mimics. As previously noted, evaluating differences in Doppler waveforms, in conjunction with using other imaging modalities and conducting detailed patient history-taking, is vital for accurate diagnosis.
Notes
Author Contributions
Conceptualization: Kwon LM, Park SY. Data acquisition: Park MS, Im D. Data analysis or interpretation: Park MS, Im D, Kwon LM, Hong WJ. Drafting of the manuscript: Park MS, Im D. Critical revision of the manuscript: Kwon LM, Park SY, Hong WJ. Approval of the final version of the manuscript: all authors.
No potential conflict of interest relevant to this article was reported.
References
Article information Continued
Notes
Key points
Deep vein thrombosis (DVT) presents with a range of symptoms, from asymptomatic to swelling, pain, and skin color changes. Doppler ultrasonography (US) and computed tomography venography are commonly employed diagnostic modalities for DVT. Accurate diagnosis of DVT, distinguishing it from other conditions such as pelvic malignancy, pregnancy, and lymphedema is essential for ensuring appropriate treatment strategies. We categorize true DVT and DVT mimics according to the different waveform patterns observed in Doppler US. This review provides imaging findings of DVT and its various mimics, emphasizing the importance of identifying these conditions in clinical practice.