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170 Direct contrast venography
(a) (b)
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(b)
Figure 15.1 (a) Tourniquet is applied for the first part of
the (arrow) study in order to direct the contrast mixed
blood into the deep veins. Note that the anterior tibial
vein is hardly filled. (b) The tourniquet has now been
released. Superficial vein do now fill (arrow) and the anterior tibial veins are also filled (arrow heads).
Typically, a tourniquet is tightly placed around the ankle
at the beginning of the examination (Figure 15.1). e pur-
pose of the maneuver is to direct the contrast into the deep
venous system. is enables examination of the deep veins of
the calf. Because of how supercial the anterior tibial vein is
at the ankle level, it may not ll with the tourniquet applied.
When the deep veins have been evaluated, the tourniquet is
released; the supercial veins will ll with further contrast
injection, as will the anterior tibial vein and the muscular
branches, if they have not lled already (Figure 15.1).
Typically, a second tourniquet is placed around the
upper or lower part of the knee. e purpose of this is to
delay the contrast ow to the thigh veins, allowing time to
adequately evaluate the lower leg veins. is tourniquet is
released, typically aer the ankle tourniquet is released, and
then a larger bolus of contrast-enhanced blood will enter
the thigh veins and ow towards the pelvic veins (Figure
Figure 15.2 Before (a) and after (b) release of the tourni-
quet (arrow) at the knee. Note the normal looking dupli-
after the release (arrow head). Contrast will now fill the
thigh veins and by squeezing the calf contrast bolus can
be pressed up into the thigh veins.
15.2). Up to this time, the table has been kept tilted with the
head end at 40–60°. When the thigh veins have been evaluated, the head end of the table can be lowered to horizontal
level or even to a head down (Trendelenburg) position, and
the contrast-enhanced blood can be observed owing into
the pelvic veins and up to the inferior vena cava.
During the venogram, the examiner can turn the leg
inwards and outwards and take X-rays in dierent obliquities in order to better understand the anatomy and any
possible pathology.
By pressing on the sole of the foot, contrast lling the
plantar venous plexus (Figure 15.3) can be ejected up into
the calf, which will increase the visualization of the calf
veins. A similar technique can be applied to the higher leg
segment, when manual compression of the calf forces contrast into the thigh veins, increasing the opacication of
these veins.
e contrast of choice is non-ionic contrast medium,
typically with 300 mg/mL of iodine. For good lling of the
venous system, 100–150 mL of contrast should be injected
rmly. It is best to have an assistant injecting the contrast
while the person performing the study rotates the leg medially and laterally under uoroscopic visualization and takes
images (X-rays) intermittently for review and documentation (Figure 15.4). Dierent positions of the limb help with
three-dimensional understanding and clarify the anatomy
and possible pathology.
15.2 Lower extremity ascending venography 171
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Figure 15.3 The plantar veins are nicely filled (arrow).
By compressing the sole, a bolus of contrast can be
“squeezed” into the calf veins increasing the visibility of
the calf veins.
15.2.2 Indications
Diagnosis of DVT was the main indication for ascending
venography until ultrasound took its place. Ascending
venography still has its place in a select group of patients
where ultrasound has either been negative or inconclusive,
but with high suspicion of DVT, as well as in instances
where ultrasound cannot be relied upon or cannot be performed for some reasons (e.g., presence of a cast, severe
swelling, scar tissue, etc.). e American College of Chest
Physicians recommendations for the diagnosis of DVT published in 2012 stated that: “In patients with suspected rst
lower extremity DVT in whom [ultrasound] is impractical
(e.g. when leg casting or excessive subcutaneous tissue or
uid prevent adequate assessment of compressibility) or
nondiagnostic, we suggest [computed tomography] scan
venography or magnetic resonance (MR) venography, or
MR direct thrombus imaging could be used as an alternative to venography.”
when high-quality venography is available, patients who are
not averse to the discomfort of venography, are less concerned about the complications of venography, and place
a high value on avoiding treatment of false-positive results
are likely to choose conrmatory venography if ndings
6
ey also add that: “In circumstances
Figure 15.4 (a) Lateral view from a right lower extremity
venogram.
clarifies the anatomy which is normal but the anterior
tibial vein is not filled well, probably due to the tourniquet
compressing the vein at the ankle.
(b) Front view (PA). Comparing the two views
for DVT are less certain (e.g. a short segment of venous no
compressibility).” e new problem is related to the lack of
experience of some physicians/institutions. Indeed, the performance of this study demands an understanding of the
technical aspects, as well as extensive training in the practice and interpretation of the results/images.
In many cases, acute DVT causes occlusion of the vein,
which will then be seen on the venography as an abrupt
termination of the contrast-lled vein (Figure 15.5a).
Frequently, there is slight ow around the thrombus—
between the vein wall and the thrombus—giving an impression of lines up along the vein, referred to as the “tram track
5, 7,8
sign” (Figure 15.5b).
Abrupt occlusion and the tram
track sign are oen regarded as the diagnostic signs of acute
DVT. e thrombus may not be occlusive, but rather rmly
adherent to the wall of the vessel on one side, but allowing contrast to ow around the thrombus (the lling defect
sign) (Figure 15.5c).
Chronic post-thrombotic changes are easily documented
on an ascending venogram. Use of an ankle tourniquet is
very important to direct the contrast into the deep vein system. If there are chronic thrombotic changes in the deep
veins, the pressure in the deep veins is typically high and
172 Direct contrast venography
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Figure 15.5 (a) Occlusion (arrow head) of one of the two peroneal vein branches with a filling defect (arrow). (b) Tra m
tracks are faintly seen as contrast is traveling between the thrombus and the vessel wall (arrows) and the density is most
when seen “tangential.” (c) Thrombus adherent to the vein on one side but allowing flow around it (arrows) on the opposite side. Sometimes it is only held in place by the thrombus caudal and then it is referred to as a free floating thrombus or
thrombus tail.
ow is diverted into the supercial system. e degree of
post-thrombotic changes varies from a patent vein with
possible smaller-than-expected diameter and lack of valves
(Figure 15.6a) to complete occlusion with no lling of the
vein lumen. In-between ndings, corresponding to septations or webs from the thrombus recanalization process,
involve small strands of contrast tracking along the previously healthy veins, looking like a “water lter” (Figure
15.6b).
Venography of patients with Klippel–Trenaunay syn-
drome presents a logistical problem. e indication for a
venogram in this case is to demonstrate the patency and
size of the deep venous system, the extent of the supercial veins, and the communication from the supercial
system to the deep system. e deep system can oen be
small (hypoplastic); therefore, it is important to have tight
tourniquets around the ankle in order to divert the contrast into the deep system (Figure 15.7). In dicult cases,
Alomari9 recommended identifying the perforating veins
initially using ultrasound. Tourniquets could then be
placed at the level of the identied perforators, trying to
prevent early lling of the perforators,9 so that the deep
system can be better evaluated. In other instances, it may
be the marginal (lateral veins) and other congenital portions of the system that are of interest for pre-operative
evaluation. In such cases, large volumes of contrast may
9
be needed to ll the veins adequately
; therefore, Alomari9
recommended using diluted contrast and subtractions
imaging.
Figure 15.6 (a) Right lower leg ascending venogram.
Note normal valve sinuses in the anterior tibial vein (arrow)
indicative of normal vein. The peroneal vein is smooth
with “wave” outlines and no valves, indicative of chronic
postthrombotic changes (arrow head). Note varicosity of
the small saphenous vein with filling of the vasa vasorum
(hollow arrow head) possible indicating recent superficial
thrombophlebitis. (b) Typical postthrombotic changes
with a “water filter” appearance from the recanalization’s
process with webs (arrow).
15.3 Lower extremity descending venography 173
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Left
Figure 15.7 Klippel Trenaunay syndrome left side. (a) Prominent greater saphenous vein appearing to communicate with
the deep vein (arrow head).
saphenous vein drains prepubic into the contralateral greater saphenous vein (arrow head).
Currently, perforators are localized and evaluated for
incompetence using ultrasound and Doppler, but the
(b) Small femoral vein (arrow). No filling of the common femoral vein (arrow) and the greater
15.3 LOWER EXTREMITY DESCENDING
VENOGRAPHY
technique of identifying and marking perforators with
ascending venography can be helpful. When looking for
an incompetent perforator, a tourniquet should be placed
around the ankle to force the contrast into the deep venous
system and prevent contrast ow directly into the supercial system. On ascending venogram, an incompetent
Ultrasound with Doppler can give accurate indications of
the location of the venous valvular incompetence. In the
1980s, descending venography was popularized, mainly
for evaluating valvular competence in the central lower
extremity veins as workup for valvular surgery.
14
perforating vein can be seen lling from the deep venous
system towards the supercial system (Figure 15.8).10 It
helps to have a measuring device (radiopaque ruler) next
to the examined leg at the same time, so that the perforators can be identied on the leg using bone landmarks
such as the malleoli.
11
How good is ascending venography at detecting acute
DVT? Ascending venography served as the reference study
(gold standard) when evaluating new technology for the
diagnosis of DVT. Hull et al.12 followed patients who had
negative venography for DVT and found that two out of
160 (1.3%) patients who were not treated based on negative
ascending venography presented within 8 days with veriable DVT. is was felt to be a strong indication that patients
with symptoms that are suggestive of DVT but with negative ascending venograms could safely forgo treatment.12
Ascending venography requires expertise and training, and
one study found that 10%–15% of ascending venography
examinations were inadequate for diagnostic purposes due
to insucient contrast.
13
15.3.1 Technique
Descending venography requires placement of a catheter at
the common femoral vein level (junction of the external iliac
and common femoral vein), or at the popliteal vein level in
the case of competent common femoral and femoral valves
but suspicion of popliteal and calf incompetence (this may
require popliteal vein puncture).15 Access can be gained
from any accessible vein where a catheter can be advanced
to the common femoral veins, such as the internal jugular
veins, arm veins, contralateral common femoral vein, and
even the ipsilateral common femoral vein.
is performed on a tilt-table with the head end elevated to
approximately 60°. A footrest is in place and a block placed
under the contralateral foot such that the studied leg is free.
Contrast is then injected at 7 mL/second, with a total volume
of 70 mL, and the patient is asked to perform the Valsalva
maneuver during the injection. Care has to be taken that the
X-ray equipment is positioned such that the contrast can be
14,16
e procedure
174 Direct contrast venography
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grade 3 indicates incompetence of the popliteal vein but
not beyond that, not opacifying the deep veins of the calf;
and nally, grade 4 reux includes the deep veins of the calf
down to the ankle level. is grading is for the deep veins
only, but by positioning the catheter close to the ostium of
the greater saphenous vein, reux in that vein can also be
evaluated in a similar manner. It is important to note that
the test will not give any indication of the competency of
the valve beyond the most cephalic competent valve unless
a catheter is placed below that level, either with direct puncture or by advancing a catheter distal to that level.
15.3.2 Indications
Figure 15.8 A perforating vein (arrow) from the poste-
rior tibial vein to superficial varicosities. Note tourniquet
around the ankle (arrow head).
followed below the knee and up to the inferior vena cava during and immediately following the injection.
Using uoroscopy, the examiner observes contrast ow
down the leg and images are taken, typically consisting of
spot images, but the uoroscopic evaluation can also be
stored as a “video recording.”17 e reux is then graded
based on how far down the leg along the axial deep veins the
contrast descends during the injection.
14,18
Grade 0 indicates
no contrast beyond the common femoral vein conuence;
grade 1 indicates reux into the femoral vein down to, but
not beyond, the mid-thigh (Figure 15.9); grade 2 indicates
reux beyond the mid-thigh but not into the popliteal vein;
is study is mostly used to map for valve surgery.
17
Descending venography is invasive and ultrasound with
Doppler has very much replaced it for patient workup. One
of the challenges of the interpretation of the examination
is that contrast may “leak” through the valves. It is oen
dicult to decide whether this is true reux or clinically
unimportant “leaky valves.”
15.4 UPPER EXTREMITY VENOGRAPHY
Venography of the upper extremity is, in many regards,
akin to what was described for the lower extremity.
Venography is rarely used for the diagnosis of DVT of
the upper extremity, but occasionally ultrasound is not convincing or uncertain, and in those cases, venography provides the answer.
15.4.1 Technique
e venogram is carried out in a similar way to lower
extremity venogram. An 18–20-gauge Angiocath is placed
into a dorsal hand vein and 20–30 mL of non-ionic contrast
with 300 mg/mL of iodine is injected. A tourniquet can be
placed at the elbow level or just above in order to force the
contrast into the deep vein system. e same criteria are
used to diagnose thrombus as for lower extremity DVT.8
Sometimes, the venogram is performed with injection into
a dorsal hand vein. is is done for the purposes of delineating the venous anatomy, such as before the creation of a
dialysis stula. In such a case, it is best to place the access
needle peripherally in order to achieve dispersal of the contrast into the supercial veins as well as the deep veins.
Venous thoracic outlet syndrome is caused by compression of the subclavian vein as it passes out of the chest in
front of the anterior scalene muscle, behind the costoclavicular muscle and between the collarbone and the rst rib.
Venography was the most-used test for its diagnosis, but
now computed tomography and MR imaging have replaced
venography for the most part,
onstrates whether there is occlusion or not, without identifying the structures around the vein.
Venography for thoracic outlet syndrome is typically
done with the patient lying at on the examination table.
19,20
as venography only dem-
15.4 Upper extremity venography 175
(b)
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Left
Figure 15.9 Bilateral lower extremity descending venogram. Puncture was made into the right common femoral vein and
a catheter then advanced over the bifurcation into the left common femoral vein and the left extremity was examined.
The catheter was then pulled back into the right external iliac vein just above the puncture and the right veins evaluated.
(a) Right leg venogram demonstrates grade 1 reflux into the profunda femoral and femoral veins (arrows) with reflux into
a large and incompetent greater saphenous vein (arrow head).
thigh vessels. See competent valves (arrows). Also note postthrombotic changes in the greater saphenous vein which is
incompetent (arrow head).
An 18–20-gauge Angiocath is placed in an antecubital vein
and 20 mL of non-ionic contrast and 300 mg/mL of iodine
are injected rmly. ree separate studies are typically
done: the rst one has the arm lying neutral by the patient’s
(b) Left leg venogram shows Grade 1 reflux into the mid-
the third injection, one can usually see impression at the
thoracic outlet in the case of compression. e diagnosis
is made by the imaging of collaterals with an obstruction,
typically at the inner border of the rst rib (Figure 15.10).
side; the second has the arm reaching out at 90° holding
a weight, such as a 1 L saline bag, and the same injection
15.4.2 Indication
is repeated; and the nal injection is then performed with
the arm stretched above the head. On the second injection,
impression at the pectoralis minor muscle is visible, and on
(a) (b) (c)
Left
Direct venography is a dying imaging technique, giving way to
more advanced cross-sectional imaging, such as MR imaging,
Figure 15.10 Left upper extremity venogram with maneuvers directed at the diagnosis of thoracic outlet syndrome. (a)
Neutral position. The subclavian vein is narrow (arrow) at the medial vein and there are collaterals bridging (arrow head).
(b) With the arm at 90° the central subclavian vein is obstructed (arrow) and the collaterals are still seen (arrow head). (c)
With the arm stretched above the head the subclavian vein is narrowed (arrow) but the collaterals do not fill (arrow head)
probably as they are compressed.
Left
Left
176 Direct contrast venography
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computed tomography, and, not least, ultrasound. e ability to visualize surrounding structures and obtain threedimensional correlations make these studies very valuable.
e addition of ow evaluation by ultrasound is signicant.
However, direct contrast venography still has a place in the
evaluation of the patient with complex venous abnormalities.
Guidelines 2.5.0 of the American Venous Forum on direct contrast venography
Grade of
recommendation
No. Guideline
(1:strong; 2: weak)
2.5.1 We recommend contrast venography before
performing endovenous reconstructions for
acute or chronic venous disease.
2.5.2 We suggest contrast venography for patients
suspected of having acute deep vein thrombosis
only if other imaging modalities are inconclusive.
REFERENCES
10. Hach W. [Varicose veins of the deep perforating
veins—A typical phlebologic disease picture]. Vasa
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= Key primary papers
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= Major Review articles
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= Guidelines
1985;14(2):155 –7.
11. Massell TB and Ettinger J. Phlebography in the localization of incompetent communicating veins in patients
with varicose veins. Ann Surg 1948;127(6):1217–25.
1. Rabinov K and Paulin S. Roentgen diagnosis of venous
thrombosis in the leg. Arch Surg 1972;104(2):134–44.
2. Cronan JJ. Venous thromboembolic disease: The
role of US. Radiology 1993;186(3):619–30.
3. Haeger K and Sjukhuset A. Problems of acute deep
venous thrombosis: I. The interpretation of signs and
symptoms. Angiology 1969;20(4):219–23.
4. Dos Santos J. La phlebographie directe.
Conception, technique, premiers resultats. J Int Chir
1938;3:625–69.
5. Nicolaides AN, Kakkar VV, Field ES, and Renney JT.
The origin of deep vein thrombosis: A venographic
study. Br J Radiol 1971;44(525):653–63.
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6. Bates SM, Jaeschke R, Stevens SM etal.; American
College of Chest Physicians. Diagnosis of DVT:
Antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians
evidence-based clinical practice guidelines. Chest
2012;141(2 Suppl.):e351S – 418S.
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7. Andrews RT. Contrast peripheral phlebography
and pulmonary angiography for diagnosis of
thromboembolism. Circulation 2004;109(12 Suppl.
1):I-22–I-27.
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8. Deweese JA and Rogoff SM. Phlebographic patterns
of acute deep venous thrombosis of the leg. Surgery
1963;53:99–108.
●
9. Alomari AI. Diversion venography—A modified technique in Klippel–Trenaunay syndrome: Initial experience. J Vasc Interv Radiol 2010;21(5):685–9.
12. Hull R, Hirsh J, Sackett DL etal. Clinical validity of a negative venogram in patients with clinically suspected venous thrombosis. Circulation
1981;64 (3):622–5.
13. Leizorovicz A, Kassai B, Becker F, and Cucherat M.
The assessment of deep vein thromboses for therapeutic trials. Angiology 2003;54(1):19–24.
●
14. Kistner RL, Ferris EB, Randhawa G, and Kamida C.
A method of performing descending venography.
JVasc Surg 1986;4(5):464–8.
15. Perrin M, Bolot JE, Genevois A, and Hiltband B.
Dynamic popliteal phlebography. Phlebology
1988;3(4):227–35.
★
16. Kistner RL and Kamida CB. Update on phlebography
and varicography. Dermatol Surg 1994;21(1):71– 6.
17. Rosales A. Valve reconstructions. Phlebology
2015;30(1 Suppl.):50–8.
18. Herman RJ, Neiman HL, Yao JS, Egan TJ, Bergan JJ,
and Malave SR. Descending venography: A method
of evaluating lower extremity venous valvular function. Radiology 1980;137(1):63–9.
19. Demondion X, Herbinet P, Van Sint Jan S, Boutry
N, Chantelot C, and Cotten A. Imaging assessment of thoracic outlet syndrome. Radiographics
2006;26(6):1735–50.
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appropriateness criteria imaging in the diagnosis of thoracic outlet syndrome. J Am Coll Radiol
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Grade of evidence (A: high
quality; B: moderate quality
C: low or very low quality
1 B
2 B
Computed tomography and magnetic
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resonance imaging in venous disease
TERRI J. VRTISKA AND JAMES F. GLOCKNER
16
16.1 Introduction 177
16.2 Imaging technologies: CTofvenous disease 177
16.3 Imaging technologies: MRI of venous disease 185
16.1 INTRODUCTION
Current diagnostic evaluation of disorders of the venous
system have beneted from advances in state-of-theart computed tomography (CT) and magnetic resonance
imaging (MRI) applications. An understanding of the
fundamentals and the appropriate utilization of each technology will provide useful information for medical management and decisions regarding surgical interventions for
venous disease.
16.2 IMAGING TECHNOLOGIES:
CTOFVENOUS DISEASE
During the past decade, CT has become a standard noninvasive imaging modality for the depiction of a wide variety
of vascular anatomies and pathologies. Modern CT acquisitions have evolved from single-detector spiral scanners to
multichannel helical CT examinations. More recently, 256slice, 320-slice, and dual-energy CT systems have become
available in many practices, and have replaced catheterdirected vascular imaging for many diagnostic studies. e
proper application of modern CT techniques provides an
extremely accurate, time-ecient, and cost-eective diagnostic evaluation prior to surgical intervention.
e two dominant advantages of CT are the speed
and resolution of image acquisition. Modern CT acquisitions can be acquired in less than a minute during a
single breath-hold. In addition, submillimeter resolution
details are available for accurate depiction of the imaging
details communicated to clinicians using advanced postprocessing techniques and 3D displays (Figure 16.1). One
additional distinct advantage of CT compared with MRI
is the ability to demonstrate calcied densities such as
16.4 Summary 201
References 201
calcied granulomatous lymph nodes as a cause of superior
vena cava (SVC) obstruction on pre-contrast acquisitions.
e two primary disadvantages of CT imaging of the
venous system include radiation exposure and the necessity
for administration of iodinated contrast material. Atypical
abdominal and pelvic CT evaluation includes a radiation
exposure of approximately 5–10 mSv. Ongoing eorts
within the CT physics community are focused on optimizing the necessary radiation required for CT acquisitions by
tailoring the dose to the individual patient size via modulation of the radiation beam.1 Administration of iodinated
contrast material is necessary for accurate evaluation of the
venous system and, therefore, patients with a signicant
allergic reaction to iodinated contrast material or decreased
renal function should be evaluated with alternative imaging techniques, including ultrasound or MRI.
16.2.1 Clinical applications
16.2.1.1 SVC AND BRACHIOCEPHALIC VEINS
CT evaluation of the SVC is most commonly performed for
the evaluation of acute or chronic occlusive changes, and has
been shown to be a useful noninvasive imaging technique
for the diagnosis of SVC and central venous disorders.
Evaluation of post-procedural changes, including endovascular stent patency or post-operative changes of surgically
placed bypass gras, can also be performed. Regardless of
the indication, CT acquisitions are optimally performed by
the simultaneous injection of the antecubital veins using
90–100 mL of dilute contrast material in each extremity at
an injection rate of 2–3 mL/second. e bilateral arm injections provide homogeneous opacication of the innominate
veins and SVC, and avoid potential artifacts from unopacied blood within the central venous structures (Figure 16.2).
2–5
177
178 Computed tomography and magnetic resonance imaging in venous disease
(a)
(b)
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Figure 16.1 Current computed tomography technology combined with tailored acquisition techniques and post-process-
ing applications provide accurate depiction of
(a) the thoracic and (b) abdominal venous vasculature.
(a)
(c)
(b)
Figure 16.2 (a, b) Contrast-enhanced axial and (c) coronal computed tomography of the chest demonstrate artifactual low
density filling defects because of unopacified blood flow from the right jugular vein and unopacified blood from the left
brachiocephalic vein entering the opacified right brachiocephalic vein (a and c, arrows) and the superior vena cava (b and
c, arrowheads).
16.2 Imaging technologies: CTofvenous disease 179
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Subsequent injection of 20–30 cm3 of saline is helpful for
ushing the contrast material from the brachial and axillary
veins into the central venous system. CT acquisition using
thin collimation (1–2 mm) is useful in order to provide both
traditional axial images and appropriate reconstructions
that can be analyzed in the coronal, sagittal, or tailored oaxis planes. Careful review of the axial images and dedicated reconstructions are useful for optimal visualization of
venous patency, obstructed venous segments, intraluminal
thrombus, and collateral venous pathways.
On contrast-enhanced (CE) CT images, acute thrombus
within the SVC or central venous structures is characterized by a low-attenuation lling defect within the lumen of
the vessel (Figure 16.3). e involved venous segment may
be normal caliber or expanded. Chronic occlusive changes
are most commonly visualized as small, non-opacied,
brotic-appearing linear densities. Extensive upper chest
wall and azygous collaterals can be precisely depicted by 3D
images (Figure 16.4).
An advantage of evaluation of the SVC and central
venous structures by CT rather than catheter venography is
the ability of CT to accurately depict the pathology resulting
from venous occlusive changes. e most common cause
(a)
of obstruction of the SVC and upper venous structures is
malignancy, most commonly pulmonary neoplasm. e
obstruction may result from extrinsic compression due to
primary or metastatic neoplasm, or from direct invasive
changes. Other common causes of SVC obstruction include
granulomatous disease and iatrogenic occlusive changes
(transvenous cardiac pacers, central venous catheters, and
post-radiation changes). Anatomic variants of the SVC can
also be accurately visualized by CT evaluation, such as a
le-sided SVC.
16.2.1.2 INFERIOR VENA CAVA
Accurate evaluation of the inferior vena cava (IVC) requires
knowledge of potential ow artifacts that are especially
prominent due to the rapid acquisitions provided by modern CT scanning (Figure 16.5). In addition, knowledge of
anatomic variation of the IVC is important for determining the accurate evaluation of ndings due to anatomic
variation rather than pathology (Figures 16.6 and 16.7).
6–9
e ow artifacts visualized with the IVC are due to the
unopacied blood from the lower extremities entering the
infrarenal IVC, whereas the suprarenal IVC receives an
admixture of opacied blood, due to the rapid transit of the
(b)
(c)
Figure 16.3 Thrombotic occlusion of the superior vena cava. (a) Unenhanced axial image of the chest demonstrates the
location of a tunneled central venous catheter (arrows). (b) Coronal CT image acquired with iodinated contrast material
injected simultaneously via bilateral antecubital iv access shows low attenuation thrombus in the right and left brachiocephalic veins (arrows). (c) Subsequent post-lysis catheter venogram with widely patent brachiocephalic veins.
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