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Case 93 - Pseudothrombus in the inferior vena cava and other venous systems
- from Section 11 - Veins
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- By Satomi Kawamoto, Johns Hopkins University School of Medicine
- Edited by Stefan L. Zimmerman, Elliot K. Fishman
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- Book:
- Pearls and Pitfalls in Cardiovascular Imaging
- Published online:
- 05 June 2015
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- 21 May 2015, pp 288-291
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Summary
Imaging description
Filling defects within the inferior vena cava at CT or MRI may be a result of flow artifacts (Figures 93.1 and 93.4), bland thrombus (Figure 93.2) or tumor thrombus (Figure 93.3). Within the inferior vena cava, the most common filling defect seen on CT is pseudothrombosis caused by laminar flow of enhanced blood from the renal veins streaming parallel to the column of unopacified blood returning from the lower body. Its appearance is usually characteristic. Coronal image may be helpful to show the characteristic pattern of a filling defect in relation to the renal veins (Figure 93.1). Artifactual filling defects may also result from poorly enhanced blood flowing into an opacified inferior vena cava, such as inflow from hepatic veins (Figure 93.4).
Artifactual filling defects can also be seen in other venous systems such as the internal jugular vein, portal vein, superior mesenteric vein (Figure 93.5), gonadal vein, and iliofemoral vein.
Importance
Artifactual filling defects seen in the venous system on CT and MRI can mimic true thrombus. Delayed imaging after administration of intravenous contrast material may be helpful for further characterization (Figure 93.5), and familiarity with anatomy and flow effects is important to distinguish between pseudo filling defects and true thrombus.
Typical clinical scenario
Typically, pseudothrombosis is seen when enhanced and unenhanced blood flow is mixed related to normal anatomy (such as enhanced blood returning from renal veins mixed with unenhanced blood in the inferior vena cava from the lower body). Reflux of opacified blood mixed with unopacified blood may also cause pseudothrombosis; for example, retrograde contrast enhancement of the inferior vena cava in patients with right-sided heart disease (such as tricuspid regurgitation, pulmonary hypertension, and right ventricular systolic dysfunction), or related to a higher injection rate (>3ml/s) of contrast material.
Asymmetric opacification of the venous system such as the gonadal veins and iliofemoral veins can also be a cause for pseudothrombosis. Asymmetric reflux of opacified blood into the left gonadal vein, early venous return to the unilateral iliofemoral vein due to a portosystemic shunt, abdominal wall collateral veins, and renal transplant with renal vein and iliac vein anastomosis have been described as causes for pseudothrombosis.
Case 84 - Mesenteric artery anatomic variants
- from Section 9 - Mesenteric vascular
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- By Satomi Kawamoto, Johns Hopkins University School of Medicine
- Edited by Stefan L. Zimmerman, Elliot K. Fishman
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- Book:
- Pearls and Pitfalls in Cardiovascular Imaging
- Published online:
- 05 June 2015
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- 21 May 2015, pp 260-262
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Summary
Imaging description
In the classic anatomy, the common hepatic artery (CHA), left gastric artery (LGA) and splenic artery (SA) arise from the celiac axis (CA), and the superior mesenteric artery (SMA) arises from the aorta without an aberrant or accessory hepatic artery (61–76% of normal population) (Figure 84.1). There are multiple types of variant anatomy of these vessels. The most common variations are a replaced or accessory left hepatic artery originating from the LGA (9.7–12.5%), a replaced or accessory right hepatic artery originating from the SMA (7.5–10.6%), or a combination of replaced or accessory right and left hepatic arteries (2.3– 4.5%) (Figure 84.2). Less commonly, the origin of the CHA arises from the SMA (1.5–3%) (Figure 84.3) or directly from the aorta (0.2–2%) (Figures 84.4 and 84.5). In these cases the splenic artery and left gastric artery often arise directly from the aorta (gastrosplenic, or lienogastric trunk) (Figures 84.3 and 84.5). Common origin of the CA and SMA (celiacomesenteric trunk) is seen in 0.7–1.1% of population (Figure 84.6). Other uncommon variations include the splenic artery originating from SMA (splenomesenteric trunk) (0.24% [5]) (Figure 84.7), and the CHA originating from the left gastric artery (hepaticogastric trunk) (0.2– 0.3%) (Figure 84.7). Additional very rare patterns also have been described.
Typically, the common hepatic artery has a suprapancreatic, preportal course; however, there can be a variation in the pathway of CHA, such as a retrocaval course or passing through the pancreatic parenchyma, particularly when the CHA arises from the SMA (Figure 84.3).
Importance
For preoperative planning of the abdominal surgery, it is important to understand the celiac axis, hepatic arterial, and mesenteric arterial anatomy to avoid or minimize serious ischemic complications. To perform interventional radiologic procedures such as intra-arterial hepatic tumor management and embolotherapy for hemorrhage, preprocedural evaluation of variant celiac axis and hepatic arterial anatomy is important for treatment planning.
Case 99 - Inferior vena cava anatomic variants
- from Section 11 - Veins
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- By Satomi Kawamoto, Johns Hopkins University School of Medicine
- Edited by Stefan L. Zimmerman, Elliot K. Fishman
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- Book:
- Pearls and Pitfalls in Cardiovascular Imaging
- Published online:
- 05 June 2015
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- 21 May 2015, pp 308-311
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Summary
Imaging description
Inferior vena cava (IVC) anomalies reflect an abnormal regression or persistence of the various embryonic veins, and there are numerous variations. In patients with double (right and left) IVC, two oval structures are seen on both sides of the abdominal aorta on axial images (Figures 99.1 and 99.2). There may be significant discrepancy in the size of the two veins. Typically the right and left IVCs join to form a single right IVC at the level of the left renal vein (Figures 99.1 and 99.2). Different from dilated gonadal vein, the left IVC continues caudally to the left common iliac vein (Figure 99.1).
Retrocaval ureter is an anomaly related to the development of the inferior vena cava. The proximal right ureter is positioned posterior to the IVC, and then courses to the left of the IVC, and finally crosses anterior to the IVC (Figure 99.2). Hydronephrosis due to ureteral obstruction may occur in patients with retrocaval ureter.
In patients with interruption of the IVC with azygos or hemiazygos continuation, the hepatic segment of IVC is absent (Figure 99.3), and the renal segment of IVC receives blood return from both kidneys and passes posterior to the diaphragmatic crus, and enters the thorax as the azygos or hemiazygos vein (Figure 99.3). The hepatic veins drain directly into the right atrium. In these patients, the azygos or hemiazygos vein is dilated (Figure 99.3), reflecting the increased flow through these vessels.
Importance
IVC anomalies usually are an incidental finding and do not have a clinical significance. However, it may simulate an abnormal structure such as lymphadenopathy or a mass. Before interventional or surgical procedures, such as IVC filter placement, anomalous anatomy of the IVC is important to be recognized. For example, in patients with double IVC, recurrent pulmonary embolism following placement of an IVC filter is possible.
Other uncommon types of IVC anomaly include IVC agenesis, right-sided double IVC, and left IVC with left retrocaval ureter. In patients with IVC agenesis, recurrent deep venous thrombosis may occur.
Case 92 - Catheter malpositions
- from Section 11 - Veins
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- By Satomi Kawamoto, Johns Hopkins University School of Medicine
- Edited by Stefan L. Zimmerman, Elliot K. Fishman
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- Book:
- Pearls and Pitfalls in Cardiovascular Imaging
- Published online:
- 05 June 2015
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- 21 May 2015, pp 285-287
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Summary
Imaging description
Catheter malpositions are found by identifying the tip of the venous or arterial catheter in the incorrect position, either within the incorrect vessel, or advanced too far or too short for acceptable use (Figures 92.1 to 92.4). Malpositions can occasionally be challenging to identify on radiographs due to overlying structures; however, they can typically be resolved with adjustments to brightness and contrast. Catheter malpositions are easily identified by cross-sectional imaging but are not uncommonly missed due to reader oversight.
Importance
Central venous catheterization is commonly used in modern medicine for various purposes; however, more than 15% of patients who receive these catheters have complications. These complications include mechanical and chemical injury to the vessel wall with thrombus formation, development of a fibrin sheath, infection, and misplacement into other vessels.
Malposition of central venous catheter placement may occur when advancing a catheter into an incorrect vein, or extending a catheter too far distally within a vessel. Malposition of a central venous catheter can result in complications including thrombosis, and vascular perforation or even cardiac perforation and pericardial tamponade. Positioning a catheter tip into the right atrium is thought to increase the likelihood of cardiac arrhythmias. It is important to detect malposition of a central venous catheter on imaging studies.
Typical clinical scenario
There is controversy regarding the correct position for the tip of a central venous catheter. When a catheter is placed from the internal jugular vein or upper extremity veins, the traditional approach has been to place the tip of the central venous catheter within the superior vena cava; however, many believe that the performance and durability of the catheter will be improved by positioning the catheter tip within the upper right atrium. Catheter malposition may occur in the azygos vein, hemiazygos vein, internal mammary vein, or contralateral innominate vein. Positioning of the catheter in an anomalous vein or a venous collateral may occur, including persistent left superior vena cava, dominant supreme intercostal vein, and pericardiophrenic vein. In patients with central vein occlusion due to thrombus or external compression, a central venous catheter may be advanced to an unintended position.
Case 96 - Nutcracker syndrome
- from Section 11 - Veins
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- By Satomi Kawamoto, Johns Hopkins University School of Medicine
- Edited by Stefan L. Zimmerman, Elliot K. Fishman
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- Book:
- Pearls and Pitfalls in Cardiovascular Imaging
- Published online:
- 05 June 2015
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- 21 May 2015, pp 299-301
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Summary
Imaging description
The nutcracker phenomenon, also known as left renal vein entrapment, refers to the compression of the left renal vein between the aorta and the superior mesenteric artery (Figures 96.1 and 96.2), with impeded outflow of the left renal vein. Compression of the left renal vein can cause left renal-to-gonadal vein reflux resulting in pelvic congestion and varicocele. Patients may also have dilated, tortuous collateral veins around the left kidney, and left retroperitoneum (Figure 96.1). On sagittal images, an abnormally small angle between the abdominal aorta and superior mesenteric artery (normal: close to 90 degrees) can be seen (Figures 96.1 and 96.2). Asymmetric delayed cortical enhancement of the left kidney on the nephrographic phase of CT has been described. On excretory phase CT, notching and displacement of the left renal collecting system and ureter due to dilated veins have also been described.
Impeded outflow of the left renal vein has also been reported in association with a retroaortic course of the left renal vein. In this situation, the retroaortic left renal vein is compressed between the aorta and the vertebral column (Figure 96.1), which is called “posterior nutcracker.”
Importance
Symptoms of nutcracker syndrome are complex and include left flank and abdominal pain, macroscopic or microscopic hematuria, left renal-to-gonadal vein reflux resulting in pelvic congestion syndrome in females, varicoceles in males, orthostatic proteinuria, lower limb varices, and chronic fatigue symptoms. The diagnosis of nutcracker syndrome is often difficult and is commonly delayed. Differentiation should be made between asymptomatic dilatation of the left renal vein (nutcracker phenomenon) and symptomatic patients (nutcracker syndrome).
Typical clinical scenario
The exact prevalence of nutcracker syndrome is unknown but may be slightly higher in females. Most symptomatic patients are in their second or third decade of life, and there may be a second peak in middle-aged women. Spontaneous resolution of the nutcracker phenomenon has been described in children.
Hematuria is the most commonly reported symptom. Lopatkin et al. postulated that increased pressure in the venous system could rupture the thin-walled septum between the small veins and collecting system in the renal fornix resulting in hematuria.
Case 7 - Pseudolymphadenopathy due to fluid in the pericardial recess
- from Section 1 - Cardiac pseudotumors and other challenging diagnoses
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- By Satomi Kawamoto, Johns Hopkins University School of Medicine
- Edited by Stefan L. Zimmerman, Elliot K. Fishman
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- Book:
- Pearls and Pitfalls in Cardiovascular Imaging
- Published online:
- 05 June 2015
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- 21 May 2015, pp 22-25
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Summary
Imaging description
Within the pericardial cavity, there are several recesses and sinuses where fluid can collect in close contiguity to the major vessels and lymph nodes, and can be misinterpreted as lymphadenopathy or mediastinal mass. The posterior portion of the superior aortic recess lies directly posterior to the ascending aorta, and is seen as a well-defined crescentic fluid collection on CT (Figure 7.1). The superior aortic recess is usually caudal to the aortic arch, but some- times extends cephalad and rightward into the right paratracheal region between the brachiocephalic vessels and the trachea (Figure 7.2), even in patients without pericardial effusion. This is called the “high-riding” superior pericardial recess and may mimic hypodense paratracheal lymphadenopathy or a cystic mediastinal mass. Fluid accumulation within the pericardial “sleeve” recess adjacent to the right inferior pulmonary vein can also mimic adenopathy (Figure 7.3).
Importance
With recent technological advances that provide high temporal and spatial resolution there has been improved visualization of fine anatomic details of the pericardium, resulting in the routine visualization of the pericardial recesses. A pericardial recess with prominent fluid may simulate hypodense lymphadenopathy or a cystic mass, especially in the setting of known primary malignancy.
Typical clinical scenario
A pericardial recess is typically incidentally found on chest CT imaging. The pericardial cavity is a potential space between the parietal and visceral layers of the serous pericardium. It normally contains a small amount of serous fluid (15–25ml). The superior aortic recess is the upward extension of the transverse sinus of the pericardial cavity, and seen in 47% of patients without known pericardial disease. The superior pericardial recess is the posterior division of the superior aortic recess, and is usually seen just caudal to the aortic arch. However, it may extend more superiorly in the right paratracheal region, and may mimic a paratracheal lymph node or cystic mass. A highriding superior pericardial recess was diagnosed in 6 (2%) of 276 patients in a study by Choi et al.
Case 95 - Catheter-related thrombus and incidental small vein thrombosis
- from Section 11 - Veins
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- By Satomi Kawamoto, Johns Hopkins University School of Medicine
- Edited by Stefan L. Zimmerman, Elliot K. Fishman
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- Book:
- Pearls and Pitfalls in Cardiovascular Imaging
- Published online:
- 05 June 2015
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- 21 May 2015, pp 295-298
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Summary
Imaging description
Thrombosis within the relatively small veins such as the gonadal vein, inferior mesenteric vein, upper extremity veins, and thrombosis related to a central venous catheter may be symptomatic, but can also be an incidental finding on CT or MRI. Non-occlusive venous thrombosis is typically seen on contrast-enhanced CT as an intraluminal filling defect surrounded by contrast material (Figures 95.1 to 95.3). When the vein is occluded by thrombus, the venous lumen is not opacified. Central venous catheter-related thrombosis is seen as a filling defect within the vein around or attached to the catheter (Figure 95.3).
Importance
Thrombosis in relatively small veins can be easily overlooked on routine CT examination. Ovarian vein thrombosis has been considered rare, but recent data suggested that the diagnosis is more common than previously thought with the widespread use of cross-sectional imaging. Anticoagulation is the main-stay of treatment for ovarian vein thrombosis.
The clinical significance of central venous catheter-related thrombosis remains undefined, although all thromboses have the potential to embolize, and patients often receive an anticoagu- lant therapy after detection of catheter-related thrombosis.
Typical clinical scenario
Classically, ovarian vein thrombosis predominantly occurs in the postpartum period. It is also associated with pelvic inflammatory disease, gynecological malignancy, hypercoagulability, and surgery. Clinical presentation of ovarian vein thrombosis is variable. Patients may be asymptomatic, and thrombosis may be detected incidentally on CT, particularly after hysterectomy and salpingo-oophorectomy. Other patients may present with fever and abdominal pain. Complications of ovarian vein thrombosis include extension of thrombus into the renal veins and the inferior vena cava, and pulmonary thromboembolism. In asymptomatic patients, usually no perivascular stranding is seen on CT. However, in patients with puerperal septic thrombophlebitis of the ovarian vein, tortuosity and perivascular edema are often associated. Thrombosis of the ovarian vein is more commonly seen on the right side, likely related to long length of the right ovarian vein, lack of retrograde flow, and multiple incompetent valves.
Septic thrombophlebitis of the inferior mesenteric vein can be associated with sigmoid diverticulitis.
Case 97 - May–Thurner syndrome
- from Section 11 - Veins
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- By Satomi Kawamoto, Johns Hopkins University School of Medicine
- Edited by Stefan L. Zimmerman, Elliot K. Fishman
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- Book:
- Pearls and Pitfalls in Cardiovascular Imaging
- Published online:
- 05 June 2015
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- 21 May 2015, pp 302-304
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Summary
Imaging description
May–Thurner syndrome, also known as iliac vein compression syndrome, or Crockett syndrome, is symptomatic compression of the left common iliac vein between the right common iliac artery and the lumbar vertebrae. Axial CT images will show that the right common iliac artery compresses the left common iliac vein (Figures 97.1 and 97.2). Patients with May–Thurner syndrome have an asymmetrically small left common iliac vein, which measured an average of 3.5mm in diameter in a study of 10 patients by Oguzkurt et al., which was significantly smaller than that in control subjects (11.5mm). The abnormality can be confirmed by iliac venography obtained via femoral access, which will demonstrate compression of the left common iliac vein in association with a pressure gradient (Figure 97.1). Patients with May–Thurner syndrome have a higher risk for acute or chronic deep venous thrombosis of the left-sided lower extremity (Figure 97.1). In patients with May–Thurner syndrome with chronic left common iliac venous occlusion, tortuous pelvic venous collaterals, which may connect to the contralateral veins, may be seen (Figure 97.2).
Importance
May–Thurner syndrome is important to recognize in patients with persistent left leg edema because relief of the mechanical compression of the left common iliac vein can prevent the development of deep venous thrombosis and venous insufficiency. Endovascular treatment with angioplasty and stent placement has been shown to be a safe and effective means of treating May–Thurner syndrome.
Typical clinical scenario
Patients with May–Thurner syndrome may present with acute or chronic left leg edema, limb pain, venous claudication, varicosities, deep venous thrombosis, chronic venous stasis, ulcers, phlegmasia cerulea dolens, or pulmonary embolism. This condition has been estimated to occur in 2% to 5% of patients who undergo evaluation for lower extremity venous disorders. It occurs predominantly in young to middle-aged women.
Contrast-enhanced CT or MRI typically shows external compression of the left common iliac vein caused by the right common iliac artery.
Case 90 - Pseudolipoma of the inferior vena cava
- from Section 11 - Veins
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- By Satomi Kawamoto, Johns Hopkins University School of Medicine
- Edited by Stefan L. Zimmerman, Elliot K. Fishman
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- Book:
- Pearls and Pitfalls in Cardiovascular Imaging
- Published online:
- 05 June 2015
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- 21 May 2015, pp 278-280
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Summary
Imaging description
Localized fat collection adjacent to the intrahepatic inferior vena cava is an uncommon incidental benign finding on CT. It is usually seen as a round (Figure 90.1) or oval (Figure 90.2) fat collection on axial CT. It is located at or above the level of the confluence of the hepatic veins and the inferior vena cava, and usually medial or anterior to the inferior vena cava, but can be seen posterior to the inferior vena cava. It demonstrates apparent fat attenuation on CT. On axial images, it may mimic a fat-containing lesion within the lumen of the inferior vena cava because of the acute angle of the fat collection with respect to the wall of the inferior vena cava. The right diaphragmatic crus forming a thin line medial to the fat collection may resemble the medial wall of the inferior vena cava on axial image (Figure 90.1).
Importance
Pericaval fat collection adjacent to the intrahepatic inferior vena cava represents a partial volume artifact of pericaval fat above the caudate lobe rather than true intraluminal lesion, and is usually of no clinical significance. However, it can be misdiagnosed as a mass in the inferior vena cava. Therefore, it is important not to misinterpret this finding as an abnormality of the inferior vena cava, such as thrombus or tumor.
Typical clinical scenario
The prevalence of pericaval fat collection near the intrahepatic inferior vena cava is considered rare, and this finding occurred in 0.5–0.55% in large CT studies. In patients with chronic liver disease, it is more commonly seen. Gibo et al. reported that pericaval fat collection was seen in 16 (26.2%) of 61 patients with chronic liver disease.
Pericaval fat collection near the intrahepatic inferior vena cava is related to anatomic variation of the subdiaphragmatic inferior vena cava, and chronic liver disease. Han et al. reported that the rightward angulation and narrowing of the intrahepatic inferior vena cava caused the pericaval fat collections to appear within the lumen of the inferior vena cava on axial CT images (Figures 90.1 and 90.2).
Case 91 - Pseudomass from varicose veins
- from Section 11 - Veins
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- By Satomi Kawamoto, Johns Hopkins University School of Medicine
- Edited by Stefan L. Zimmerman, Elliot K. Fishman
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- Book:
- Pearls and Pitfalls in Cardiovascular Imaging
- Published online:
- 05 June 2015
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- 21 May 2015, pp 281-284
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Summary
Imaging description
Varicose veins may be seen as round or oval soft tissue density masses on CT, particularly when they are seen on a plane perpendicular to its course. Typically, varicose veins are easily diagnosed with intravenous contrast material, which helps to detect the continuity between varicose veins and other venous structures, and to determine the true vascular nature of the varicose veins. However, when contrast is not administered or enhancement of the vein is poor due to early arterial phase or thrombosis, it may be confused with lymphadenopathy or another mass (Figure 91.1).
Reformatted coronal or sagittal images along the course of the dilated vein will help to differentiate dilated veins from other pathologies. In patients with venous obstruction, knowledge of collateral pathways in chest, abdomen, and pelvis is essential to avoid misinterpretation.
Importance
Varicose veins are commonly encountered at cross-sectional imaging of the thorax and abdomen. These vessels can be mistaken for adenopathy, which could lead to improper staging of patients with cancer or unnecessary work-up for malignancy. Erroneous biopsy of varicose veins may lead to profound hemorrhage.
Typical clinical scenario
Varicose veins are enlarged and tortuous venous channels, which are commonly caused by retrograde flow due to incompetency of valves or obstruction to flow. Obstruction of the venous flow may be secondary to thrombus, external compression, or congenital.
In patients with occlusion of the superior vena cava and its tributaries, the collateral venous pathways are often categorized into four main pathways: lateral thoracic, internal mammary, azygos, and vertebral pathways (Figure 91.2). In the abdomen, internal mammary pathways form anastomoses with the superficial epigastric veins, which may be seen in the anterior abdominal wall of patients with superior vena cava obstruction (Figure 91.3). When the inferior vena cava is obstructed, the ascending lumbar vein, which drains into the azygos-hemiazygos system, may be dilated. Dilated azygos or hemiazygos veins can be confused with retroperitoneal, retrocrural, or paraspinal mass or adenopathy (Figure 91.4). In patients with portal hypertension, varicose veins may form in the esophagus or upper abdomen, and may simulate a mass or adenopathy (Figures 91.1 and 91.5).