Table of Contents
Page
No.
Extracranial
Carotid and Vertebral Duplex
3-4
Doppler
Spectrum Analysis 5
The
ABC's of Carotid Sonography 6
Lower
Extremity Arterial (Femoral-Popliteal) Evaluation 7
Upper
Extremity Arterial Evaluation
8-9
Diagnostic
Criteria for Peripheral Arterial Duplex Examinations 10
Lower
Extremity Venous Evaluation 11-12
Pelvic
Veins 13
Imaging
the Veins of the Calf 14
Attached: Lower Extremity Venous Scanning Technique and
Anatomy
Lower Extremity Venous Calf Scanning
Technique and Anatomy
Upper
Extremity Venous Evaluation 15-16
Attached: Upper Extremity Venous Anatomy
Diagnostic
Criteria for Venous Studies 17
Arterial
Graft Evaluation 18
Diagnostic
Criteria for Arterial Grafts 19
Evaluation
of the Groin 20
Documenting the Examination 21
Ultrasound Evaluation of Renal Artery Stenosis 22-23
Attached: Radiology 195:799-804, 1995
Radiol Clin North Am
34(5):1023-1024, 1996
Penile Blood Flow 27
Evaluation of Dialysis Fistulas 28-29
Mesenteric Ischemia Protocol and Diagnostic
Criteria 30
References 31-32
Extracranial Carotid and Vertebral Duplex
1. No
patient preparation is necessary.
2. Obtain
pertinent clinical history (including previous invasive or non-invasive
studies, previous carotid surgery, cardiac conditions, any
history of cardiac valvular disease).
3. Imaging
is usually performed utilizing a 7.5 MHz duplex transducer.
4. It
may be useful to orient yourself at first in the longitudinal plane, surveying
the entire length of the common carotid, external and internal carotid
vessels. Differentiate the internal
carotid and external carotid arteries by comparing the characteristic Doppler
waveforms, looking for branches of the external, and performing a temporal
artery tap. Low resistance flow is seen
in the internal carotid artery and high resistance in the external carotid
artery. Do not rely upon image alone to
identify these two vessels. Tapping on
the ipsilateral temporal artery should produce transmitted pulsations to the
external carotid. Look for branches
arising from the vessel to help identify the external carotid.
5.
Once oriented, image transversely
starting at the origin of the carotid and extending above the bifurcation as
high as possible. Selective images
should demonstrate areas of plaque formation at these levels. In every case, document 5 TRV images:
1. proximal CCA
2. distal CCA
3. bifurcation
4. proximal
5. proximal ECA
6. Image
longitudinally, demonstrating the common carotid artery, carotid bifurcation,
external carotid and internal carotid arteries.
7. Begin
the Doppler examination. A Doppler angle
of 40-60o should be maintained at all times if possible. The sample volume should remain as small as
possible. In cases of occlusion or
critical stenosis, the sample volume may be increased to help locate the flow
channel.
8. Color
Doppler can guide you to the areas of greatest flow disturbance. Place the sample volume in the center of the
flow channel. Adjust the angle to
conform to the flow channel.
9.
Doppler
Recordings: Record and label, measure systolic and diastolic velocities:
1.
proximal
CCA (base of neck)
2.
CCA
2 cm proximal to the bifurcation
3.
bulb
of
4.
proximal
5.
mid
6.
distal
IC
7.
proximal
external carotid ECA
All are shown with measurements of peak systolic and diastolic flow velocity. The proximal common carotid is examined with Doppler, and any abnormal or assymetric waveform which may reflect proximal disease is documented. Demonstrate transmission of ipsilateral temporal artery tapping to the external carotid artery. Record peak systolic and diastolic flow velocities within any areas of flow disturbance or stenosis of the common and internal vessels.
10. Image
and Doppler the vertebral arteries and confirm direction of flow by comparison
to the common carotid.
11. Criteria
for diagnosis can include systolic and diastolic peak velocities and ratios. Comparison
of waveforms on the right and left can be helpful in cases of very proximal or
very distal lesions which might otherwise not be obvious, or may lie outside of
view of the probe.
12. Stenoses
less then 60% are best quantified using area or diameter calculations from
transverse images and/or sagittal.
Stenoses greater than 60% are best quanitified
with Doppler.
13. When
examining patients on the intraaortic balloon pump,
consult with the radiologist concerning obtaining Doppler information with the
pump turned off for a few cycles.
Doppler Spectrum Analysis:
Diagnostic Doppler Criteria for Carotid Artery Disease
|
DIAMETER STENOSIS (CATEGORY) |
PEAK SYSTOLIC VELOCITY (cm/sec) |
PEAK DIASTOLIC VELOCITY (cm/sec) |
SYSTOLIC VELOCITY RATIO (VICA/VCCA) |
DIASTOLIC VELOCITY RATIO (VICA/VCCA) |
|
0% ( |
< 110 |
< 40 |
< 1.8 |
< 2.6 |
|
1-39% (Mild) |
< 110 |
< 40 |
< 1.8 |
< 2.6 |
|
40-59% (Moderate) |
< 200 |
< 60 |
< 1.8 |
< 2.6 |
|
60-79% (Severe) |
> 200 |
> 60 |
> 1.8 |
> 2.6 |
|
80-99% (Critical) |
> 250 |
> 100 |
> 3.7 |
> 5.5 |
See "Reference" page -
references #4, 10, 11 and 14
The ABC's of Carotid Sonography:
How to Interpret the Examination
A = Anatomy
Are
the vessels identified correctly?
How
well is the bifurcation visualized?
B = B Mode
Look
for plaque within the CCA,
Homogeneous
/ Heterogeneous
C = Color Image
Is
a stenosis visualized?
Is
there post stenotic dilatation? flow reversal?
Stenoses
less than 60% are best graded by image
D = Doppler
Inspect
the CCA for unusually high velocities or asymmetry in diastolic flow
Does
the
If
there is discordance, resolve it by rescanning
Lower Extremity Arterial (Femoral-Popliteal) Evaluation
1. No
patient preparation is necessary for the femoral-popliteal examination. However, if the iliac vessels are to be
examined, the patient should be given instructions to remain NPO after
2. A
5 MHz duplex transducer can be utilized for the femoral-popliteal
examination. A 3 MHz transducer is
usually necessary for the iliac examination.
3. Obtain
clinical history including any prior studies or surgical vascular
procedures. Previous non-invasive
testing results are utilized as a guide to the level of disease.
4. The
smallest sample volume possible should be used.
All velocities should be obtained at or near 60o to the vessel.
5. The
examination begins with the patient supine.
The common femoral artery is identified in the transverse plane at the inguinal
ligament. This vessel is then traced sagittally as far proximal as possible with imaging of the
iliac vessels if possible. Sagittal
imaging with velocity measurements are obtained from the most proximal segment
visualized and moving distally, from the common femoral artery, origin of the
profunda femoris, and the proximal, mid and distal superficial femoral artery.
6. The
patient is scanned supine to the level of the adductor canal. A mark can then be placed on the patient's
skin. The patient is turned prone or in
a decubitus position with the side being examined superior. Scanning in this position begins from the
previously placed mark with evaluation of the popliteal artery and origins of
the tibioperoneal vessels, if possible.
7. Areas
which show flow disturbance or focal plaque, or a sudden increase in velocity
are examined more critically and recorded on hard copy. Peak systolic velocity is recorded from this
area as well as from the segment of vessel immediately proximal to this segment. These velocities are used to calculate a peak
systolic velocity ratio.
8. The
posterior tibial and peroneal arteries with their accompanying paired veins are
located in the interface between the superficial and deep muscle compartment of
the posterior calf. These vessels can be
imaged longitudinally using a sagittal plane from a posterior approach or a
coronal plane from a medial approach.
The anterior tibial artery is imaged using a parasagittal
plane with the patient supine and the leg slightly internally rotated.
9. If
an occlusion is suspected, imaging in the transverse plane may show a
collateral vessel coursing obliquely away from the native vessel. Distal to the occlusion a
collateral may be seen entering the native vessel. The length of occlusion can be determined by
marking these margins on the skin and measuring the distance between the two
marks.
Upper Extremity Arterial Evaluation
1. No
patient preparation is necessary.
2. Obtain
clinical history, the results of any prior non-invasive tests, surgical
interventions, trauma, etc. The results
of bilateral segmental pressure testing should be known prior to beginning the
imaging examination, as a guide to the level of disease.
3. Imaging
the upper extremity arteries is similar to the upper extremity venous
evaluation. The patient is supine. Begin with a 5.0 MHz transducer and use a 7.5
MHz transducer at the forearm and wrist.
The subclavian artery is superficial to the vein when imaged through the
superclavicular fossa. The mid and proximal subclavian artery can
also be imaged from a position caudal to the clavicle, in which case the artery
is seen deep to the vein. Trace the
subclavian artery in long axis distally as it becomes the axillary artery, near
the junction of the cephalic and axillary veins. The axillary artery becomes the brachial
artery as it crosses the humeral head. The brachial artery trifurcates at the antecubital fossa to give
rise to the radial, ulnar and interosseous branches. Follow the radial and ulnar vessels to the
wrist.
4. Obtain
Doppler information at or near 60 degrees to the vessel. Show representative
Doppler from each native segment and additionally from any areas of altered
flow.
5. Areas
which show flow disturbance or focal plaque, or a sudden increase in velocity
are examined critically and recorded on hard copy. Peak systolic velocity is recorded from this
area as well as from the immediate proximal normal segment. These velocities are used to calculate a peak
systolic velocity ratio.
6. If
there is evidence of subclavian disease, evaluate flow direction of the
vertebral arteries, using the common carotid artery as a reference.
7. The
palmar arches and digital arteries are difficult to evaluate with color Doppler
imaging, in part due to the presence of partial arches and anatomic
variations. Digital pressures are more
helpful at this level.
8. In
evaluating thoracic outlet syndromes, non-imaging techniques are
preferred. Thoracic outlet maneuvers may
also be performed during an imaging examination if spectral analysis is
performed at the radial or ulnar artery before and during the following
maneuvers:
a. Adson maneuver evaluates compression by the
scalenus anticus
muscle or cervical rib.
The patient takes a deep breath, extends the neck back and upward and
then turns the head first to the right and then to the left.
b. Costoclavicular
maneuver evaluates compression of the neurovascular bundle between the
clavicle and the first rib. The patient
assumes an exaggerated military position with shoulders pushed backward and
pressed downward.
c. Hyperabduction
maneuver evaluates compression of the neurovascular bundle between the
coracoid process and the pectoralis minor muscle. The patient externally rotates the shoulders
and extends the arms out from the chest and then above the head.
Diagnostic Criteria for
Peripheral Arterial Duplex Examinations
1. Normal
peak systolic velocity decreases from 1.1 m/sec within the common femoral
artery to 0.7 m/sec within the popliteal artery. Normal arterial waveforms are tri-phasic. There are
no agreed upon normal velocities in the upper extremity.
2. The
peak systolic velocity ratio is independent of the location of the arterial
segment being evaluated and is utilized in peripheral arterial diagnosis. The peak systolic velocity measured in a
narrowed segment is divided by the velocity measured in a more proximal and
normal segment. The diagnosis and
grading of multiple tandem lesions is possible in this manner.
3. A
peak systolic velocity ratio of 2 corresponds with a 50 percent degree
narrowing in vessel diameter. Waveform
morphology distal to a greater than 50 percent stenosis will be monophasic, with loss of the reversed flow component.
4. A
ratio of 3 or more represents a greater than 75 percent diameter stenosis.
See "Reference" page -
references #5, 7, 8 and 13
Lower Extremity Venous Evaluation
1. No
patient preparation is necessary. Obtain
history including risk factors, history of treatment, filter placement, prior
studies, etc. The examination begins
with the patient supine. If possible,
the head of the bed should be elevated 15-20 degrees. The popliteal portion of the study is
performed either with the patient prone and the leg examined flexed 20 degrees
at the knee, or in the lateral decubitus position with the side being examined
superior.
2. Use
a 5 MHz linear duplex transducer for most studies, 3 MHz for iliac veins.
3. Comparison
of findings on the symptomatic and asymptomatic side is often helpful. (See page 11-A for anatomic
guide to the study.)
4. Imaging
begins at the level of the inguinal ligament with identification of the common
femoral vein medial and adjacent to the common femoral artery. The entire length of the common femoral vein,
superficial femoral vein, and popliteal vein are examined in the longitudinal
plane. Doppler information is obtained segmentally at each of these levels. Flow should be spontaneous and phasic. With distal
compression, there should be an augmentation of venous flow. An assessment for reflux or valvular
insufficiency should be made.
5. The
CFV should be traced and evaluated as far proximally into the external iliac
vein as possible (above the inguinal ligament).
If Doppler or imaging study is abnormal, continue proximally to the
IVC. The profunda femoral and greater
saphenous veins as they join the CFV should be evaluated. Include examination of the origins of the
tibial veins, regions of the gastroc sinuses, and the
popliteal/lesser saphenous junction.
6. Imaging
is performed in the transverse plane from the inguinal ligament to the
bifurcation of the popliteal vein into the origins of the tibial and peroneal
veins. Images of the saphenous at its
junction with the CFV should be included.
Compression maneuvers are performed along the course of the deep veins
including the saphenofemoral junction and at the
level of the origins of the tibial veins.
If clot is detected, the proximal and distal extent should be
documented.
7. Images
are obtained on a split screen showing compression and no compression at the
same level, in the transverse planes.
Required levels to document are:
1. CFV
2.
CFV/SAPH
junction
3.
proximal
SFV
4.
Mid
SFV
5.
distal
SFV
6.
popliteal vein.
8. If
there is clinical concern with respect to calf deep vein thrombosis, alert the
reading physician and examine the peroneal and posterior tibial veins as well
as the popliteal/saphenous junction, with and without compression, include
images.
9. If
there is obvious thrombus, do not continue to perform augmentation or vigorous
compression maneuvers as there is a theoretical risk of embolization.
Pelvic Veins
1. Isolated
iliac thrombus is rare and is usually related to pelvic trauma. Pelvic thrombophlebitis usually involves the
internal iliac and gonadal veins and is better evaluated with CT and MRI. When there is obstructive iliac clot, femoral
studies will show lack of phasicity of the femoral
vein. These findings can be present in
cases of iliac thrombosis or obstruction secondary to pelvic masses. Color Doppler imaging with a full urinary
bladder or endovaginal scanning in the ultrasound
department can be useful in evaluating the internal iliac vessels.
2. Cases
of suspected pelvic thrombophlebitis may require contrast CT or MRI.
Imaging the Veins of the Calf
1. The
calf is examined with the ambulatory patient sitting with the leg to be
examined dependent. Hospitalized
patients can be examined with the head of the bed elevated 20-30o and the leg abducted and externally rotated.
2. Use
a 5.0 or 7.5 MHz probe.
3. The
peroneal and posterior tibial veins are located in the interface between the
superficial and deep muscle compartment, parallel to the posterior surface of
the tibia. The peroneal veins diverge
laterally from the posterior tibial veins.
These vessels can be imaged longitudinally using a coronal approach with
the transducer placed on the medial/posterior calf. Frequently both the posterior tibial and
peroneal veins can be imaged simultaneously.
Once found in the longitudinal plane, the same vessels are reevaluated
in a transverse plane, with and without compression.
4. Image
and record findings as for the femoral-popliteal evaluation.
5. The
anterior tibial veins are difficult to visualize. Isolated thrombosis in the anterior tibial
veins is rare. These vessels can be
demonstrated using a parasagittal longitudinal plane
with the transducer placed on the anteriolateral calf
between the tibia and fibula. Edema,
obesity, and prior DVT with collateral veins results in inadequate examinations
in approximately 40 percent of patients.
Record images only if abnormal.
6. Image
and record findings as for the fem-pop evaluation.
Attached:
Lower
Extremity Venous Scanning Technique and Anatomy
Lower
Extremity Venous Calf Scanning Technique and Anatomy
Upper Extremity Venous Evaluation
1. No
patient preparation is necessary.
2. Obtain
the clinical history, including history of catheter placement, venous
punctures, malignancy, radiation therapy, etc.
3. The
patient is scanned supine.
4. Use
a 5 MHz duplex transducer, or 7.5 MHz as needed.
5. Each
segment evaluated should include assessment of the quality of venous flow by
Doppler and whenever possible, the response to compression maneuvers. Maximum venous flow in the upper extremities
will occur with inspiration.
6. Begin
with the internal jugular vein, imaged transversely from the carotid
bifurcation to the clavicle.
7. Using a supraclavicular approach, evaluate the subclavian
and innominate veins.
8. Evaluate
the middle and distal portions of the subclavian vein using an infraclavicular
approach.
9. With
the patient's arm raised to permit access to the axilla, begin imaging the
veins of the arm.
10. The
transverse scan plane is used for orientation.
Both transverse and longitudinal imaging is employed as necessary. Start high in the axilla, and image the axillary
vein and artery. The vein is
superficial to the artery. As scanning
proceeds distally, the basilic vein branches
medially.
11. The
major venous trunk below this point is the brachial vein. Venous anatomy is variable,
however, the brachial vein will split into two separate trunks which follow the
brachial artery down the medial aspect of the arm. The brachial artery and vein cross the elbow
medially and can be followed into the forearm where they divide into the radial
and ulnar vessels. The forearm veins are
paired.
12. Examine
the basilic vein by returning to the
junction of this vessel with the axillary vein.
The basilic vein is followed down the medial
aspect of the arm.
13. The
cephalic vein is superficially located and may be identified along the
anterior border of the biceps muscle. It
may join the basilic vein near the elbow through the
medial cubital vein which crosses the antecubital fossa. The cephalic vein can be followed proximally
up over the shoulder to its junction with the subclavian or axillary vein.
14. If
thrombus is detected, document the proximal and distal extent of disease.
15: Normal
images to document will include:
a. Subclavian vein
i. Color sagittal view
ii. Sagittal with duplex Doppler
b. Axillary vein
i. Color sagittal
ii. Sagittal with duplex Doppler
iii. Transverse with and without compression
c. Brachial vein
i. Transverse with and without
compression
d. Cephalic vein
i. Transverse with and without
compression
e. Basilic vein
i. Transverse with and without
compression
f. Radial and ulnar veins if forearm
symptoms
i. Transverse with and without
compression
Attached:
Upper
Extremity Venous Anatomy
Diagnostic Criteria for Venous Studies
1. The
vein collapses completely in response to pressure. The vein walls should completely coapt. This is the basis for compression ultrasound
diagnosis.
2. On
color Doppler examinations, flow should be demonstrated within the vein
lumen. Color fills the vein in response
to distal compression (augmentation).
3. Non-obstructive
thrombus will partially fill the lumen of the vein. Compression is limited by thrombus within the
lumen. On the color examination, flow
can often be demonstrated around the thrombus.
In cases of acute obstructive thrombosis the vein lumen is dilated and
filled with thrombotic material. With
acute DVT, the diameter of the vein is usually larger than the artery.
4. It
is often difficult to differentiate between chronic and acute thrombosis. Characteristics of chronic thrombosis are a
rigid texture and a contracted vein lumen.
Characteristics of acute thrombosis are a more spongy texture, the clot
may be poorly attached to the vein wall and the vein lumen is distended by
clot. Evaluation of echogenicity
alone is not a reliable means of distinguishing between acute and chronic
clot. It has been said that acute clot
is hypoechoic and chronic clot echogenic, however this has
been shown to be unreliable.
See "Reference" page -
references #2, 3, 6 and 12
Arterial Graft Evaluation
1. A
complete surgical history should be obtained.
The date of graft surgery, any post-surgical interventions and the
results of any previous non-invasive testing should be known. The type of graft material used and the
anatomy of the graft procedure should be known prior to scanning.
2. The
bypass graft should be identified in the longitudinal or transverse plane and
followed to the proximal site of anastamosis.
Scanning is then performed in the longitudinal plane, recording Doppler
velocity information from the inflow vessel proximal to the site of anastamosis
as well as segmentally throughout the graft and
within the outflow vessel if possible.
Images with Doppler waveforms are obtained at the proximal and distal
anastamosis, and at any areas which show a focal increase in peak systolic
velocity or change in diameter. As in
native arterial evaluations, a comparison of the peak systolic velocity in the
segment proximal to the site of concern is used for diagnosis of the degree of
diameter reduction.
3. Peak
systolic velocities less than 45 cm/sec indicate impending graft failure.
Diagnostic Criteria for Arterial Grafts
1. Peak
systolic velocity within the graft should be greater than 45 cm/sec. Flow below this level indicates impending
graft failure.
2. A
diameter reduction of between 50 and 75 percent is reflected by peak systolic
velocities which are greater than 100 percent of those obtained proximal to the
site of narrowing. A ratio of 2-3 is
seen.
3. Diameter
reductions of greater than 75 percent show an increase in peak diastolic
velocity of greater than 100 cm/sec with a peak systolic velocity ratio of
greater than 3. Waveform morphology is monophasic.
See "Reference" page -
references #1, 5, 7, 8 and 13
Evaluation of the Groin
1. No patient preparation is necessary.
2. Obtain relevant clinical history pertaining
to the type of interventional procedure performed, the location and extent of
the groin mass, any history of anticoagulation, and previous surgical
interventions within the groin.
3. Begin the examination using a 5.0 MHz
transducer. Orient yourself in the
transverse plane, by identifying the common femoral artery.
4. The examination should evaluate the vessels
above, at and below the skin puncture site.
Trace the common femoral artery, superficial femoral artery, and
profunda femoris artery as well as the common femoral vein, profunda femoral
vein, and superficial femoral veins, in both short and long axis. Document the relationship of any surrounding
masses to the native vessels.
5. Vary the color Doppler gain settings and use
beam steering to evaluate soft tissue masses or fluid collections for
flow. Look for soft tissue bruits to
identify sites of flow disturbance.
6. Obtain pulsed Doppler recordings from native
arteries and veins as well as from any extravascular areas which contain
flow. If a pseudoaneurysm
is present, identify the neck of the pseudoaneurysm and
image this area with simultaneous pulsed Doppler recording. If an arteriovenous fistula is suspected,
demonstrate three flow patterns: (a)
high diastolic flow within the feeding artery proximal to the fistula, (b) pulsatile venous
flow within the draining vein at the fistula, and (c) normalized arterial flow
distal to the fistula. Beware of
abnormal arterial waveforms secondary to routine arterial disease. These waveforms will appear monophasic.
7. Image the size of the hematoma, pseudoaneurysm, or aneurysm in long and short axis views.
8. Non-Invasive Treatment of Pseudoaneurysms:
a. If a pseudoaneurysm
is detected, ultrasound guided compression may be effective in thrombosing the PA.
The reading physician will determine whether or not the patient is a
candidate for compression and obtain consent to proceed from the patient and
referring physician. The procedure will
be explained to the patient by the physician.
The physician performs the compression with the assistance of the
technologist or resident.
b. Protocol:
i. Polak (AJR 161:240-241, August 1993) describes the technique for ultrasound guided compression.
ii. The
results of the attempt are documented in the chart and the referring physician
is notified of either the failure or success of the procedure.
Documenting the Examination:
1. Record
representative images in transverse and longitudinal planes at each anatomic
vascular segment, and additionally at any area of plaque, flow disturbance or
thrombus. Color images are most useful
at sites of stenosis to show altered flow.
2. Doppler
waveforms with superimposed 2D image showing site of sampling are obtained
within each arterial segment and at each site of flow disturbance. For carotids, calculate peak systolic and
diastolic velocities. For extremity
studies calculate peak systolic velocities.
3. Document
history, present Doppler data, and show location and severity of plaque.
4. Videotape
can be used when a physician is not present to check the examinaton
before the patient leaves the department.
Ultrasound
Evaluation of Renal Artery Stenosis
Attached:
1. See
attached article: Halpern
EJ, Needleman L, Nack TL, East SA: Renal artery stenosis: Should we study the main renal artery or
segmental vessels? Radiology
195:799-804, 1995
2. See
attached sample waveforms from: Mitty HA, Shapiro
BS, Parsons RB, Silberzweig
JE: Renovascular hypertension. Radiol Clin North Am 34(5):1017-1036, September 1996.
Protocol:
1. Be sure order entry is generated for both imaging and
Doppler study.
2. Obtain
relevant history (hypertension, renal failure, history of arterial disease at
other sites).
3. Perform
renal US examination as for routine renal US study. Normal exam would consist of 3 sag images (rt, midline, left ) and 3 trv images (upper, mid, lower) of each kidney. One of the sag images of the right kidney
should include liver for comparison of echogenicity.
4. Re
enter patient setup menu and choose cardiac package. The Doppler examination begins with an
evaluation of the renal artery in the hilum of the kidney, and from the
segmental arteries within the upper, mid and lower poles of the kidney
bilaterally. (see
diagram).
a.
Adjust the sweep speed to
display two or three waveforms per screen.
b. Adjust
the scale and baseline to allow the waveform to completely fill the display
area without aliasing.
c. Use
angle correction and obtain best Doppler angle possible. Record
calculations only from waveforms which are reproducible.
d. Calculate
the EARLY SYSTOLIC ACCELERATION (ESA) of a representative waveform from the
renal hilum, upper, mid and lower pole segmental arteries.
The Early Systolic Acceleration is the slope of the waveform during
the early part of systole. It is obtained
by taking the velocity in m/sec at the top of the systolic rise and dividing it
by the time it took to get there. It is
expressed as m/sec per second, or: m/sec2
A value of less than 3m/sec2 (300cm/sec2) is consistent with renal artery stenosis. Sensitivity of the ESA in detecting renal
artery stenosis is reported at 76% with a specificity of 95%.
e. A normal result does not exclude RAS
(see page 5).
5. At
the discretion of the reading physician, the main renal artery may be
examined. Stenoses involving accessory
renal arteries may be missed. Combining
both the RAR and ESA does not significantly improve results.
a. Record
angle corrected velocities from the proximal, mid and distal portions of the
main renal arteries bilaterally, and at any sites of flow disturbance.
b. Obtain
angle corrected velocity measurement from the aorta at a level between the sma and renal artery origins.
c.
The renal aortic ratio (RAR)
is calculated as renal artery velocity divided by aortic velocity. A ratio of > 3.5 is positive for renal
artery stenosis with a sensitivity of 71% and specificity of 91%.
Ultrasound
Evaluation of
Transjugular Intrahepatic Portosystemic
Shunt (TIPS)
Transjugular intrahepatic portosystemic shunts were first investigated in 1969. The technique was refined in the early 1990's using expandable metal stents and is now used to relieve portal hypertension in patients who have refractory ascites or life threatening episodes of variceal bleeding. In this procedure, the portal venous system is partially decompressed by using an expandable metallic stent to create a channel between a hepatic vein and a portal vein. Complications of the procedure include hematoma formation, stent thrombosis, stent stenosis, and stenoses developing within the draining hepatic vein.
Pre Procedure Evaluation: Obtained within 4 weeks of the TIPS
procedure
1. Evaluate liver:
a. Size
b. Echogenicity
c. Masses
d. Collections
e. Biliary
ducts (intra and extra hepatic)
f. Gallbladder
2. Evaluate
the following vessels for patency and direction of
flow:
a.
b. Measure
Vmax in the main portal vein
c. Hepatic
Vein
d. Hepatic
Artery
3.
Evaluate Ascites
4.
Measure Spleen Size - Sagittal and
Transverse
Post Procedure
Evaluation: Obtained within 48 hrs of procedure, at
1, 3, and 6 months, and then every 6 months
1-4. Follow procedures 1-4 as above, plus:
5.
Evaluate the shunt:
a. Measure stent diameter- should be
uniform
b. Look for collections around the stent
c. Document direction of flow within the
shunt
d. Record Vmax
within the proximal segment of the shunt (at least 1 cm beyond shunt inlet); obtain best angle
possible
AND
e. Record Vmax within
the mid portion of shunt and at any areas of flow disturbance
f. Record Vmax
within distal shunt
DIAGNOSTIC CRITERIA
Pre-procedure main portal vein flow should be hepatopetal, with peak velocities of 10-40 cm/sec, mean 21
cm/sec +/- 12 cm/sec.
Post procedure main portal vein flow becomes hepatofugal within the intrahepatic portal vein branches in
the majority of patients. Blood flows
towards a patent shunt.
In patients who have persistent hepatopetal flow, there may be a localized reversal of flow
at the entry site of the shunt representing local turbulence. Flow in these patients may become hepatofugal on follow up. Flow in the minority of patients
can be bi-directional and may vary with respiration. If post tips flow changes from hepatofugal to hepatopetal,
suspect shunt dysfunction.
Post procedure main portal vein velocities will
increase to mean 41 cm/sec +/- 18cm/sec.
Flow within the hepatic veins should remain
toward the IVC. Transmitted cardiac pulsations can be seen.
The Stent
The
diameter should be uniform, with no kinks.
Flow should be from the portal vein (proximal)
to the hepatic vein (distal). Flow is monophasic and
non pulsatile or slightly pulsatile. Transmitted cardiac pulsations will be
exaggerated in cases of CHF.
Peak systolic flow within the proximal (portal
end) of the stent should be 73-185 cm/sec, mean 130 (Surratt)
or 65-220 cm/sec, mean 123 cm/sec (Longo).
Velocities can be higher with quiet breathing than with suspended
respiration.
These numbers are not absolute. Use the initial study as a baseline and do
followup. Be sure to speak with the interventionalist who placed the stent in order to obtain
information regarding any unusual stent placements or difficulties they may
have had positioning the stent (i.e., placement of coaxial stents). A change in velocity over time of
>50cm/sec has been correlated with shunt dysfunction. So has an absolute velocity of less than
50-60cm/sec.
Patients who are developing a shunt stenosis
will have decreasing V max as blood is reshunted into
varices. A focal area of increased
velocity (suggested as >50cm/sec greater than adjacent segment - ref Dodd)
can also be seen. Stenosis usually
develops at the HV end. Reversed flow in
the proximal portion of the hepatic vein draining the stent is evidence of
shunt stenosis.
Post procedure hepatic parenchymal changes
Microbubbles introduced at the time of the procedure
may produce transient findings of bright areas within the periphery of the
liver.
Look
for intrahepatic hematomas, bilomas, duct obstruction.
Spleen size
The spleen will decrease in size gradually
during the months following successful shunting.
Ascites
There
should be a decrease in the amount of ascites.
References
1. Chong
WK, Malisch TA, et al: Transjugular
intrahepatic portosystemic shunt:
2. Dodd
GD,
3. Foshager MC, Ferral H, Nazarian GK: Duplex
sonography after TIPS. AJR 1995;165:1-7.
4. Freedman
AM, Sanyal AJ, et al:
Complications of transjugular intrahepatic portosystemic shunt: A comprehensive review. RadioGraphics 1993;13:1185-1210.
5. La
Berge JM, Ring EJ, et al: Creation of transjugular intrahepatic portosystemic
shunts: Results in 100 patients. Radiology 1993;187:413.
6. Longo
JM, Bilbao JL, et al:
Transjugular intrahepatic portosystemic
shunt: Evaluation with Doppler sonography.
Radiology 1993;186:529.
7. Surratt
RS, Middleton WD, Darcy MD, et al:
Morphologic and hemodynamic findings at sonography before and after
creation of a transjugular intrahepatic portosystemic shunt.
AJR 1993;160:627.
Penile Blood Flow
A. Supplies
1. T.B.
syringe
2. Alcohol
swabs
3. Prostaglandin
E-1 10 mcg/ml
4. Call
IV lab (x. 6493) when patient arrives
5. Physician
order sheet or pharmacy order sheet
6. Radiologist
has to write order for Prostaglandin 10 mi
B. Procedure
1. Sagittal scan of dorsal surface of
penis demonstrating cavernosal artery on each side. Document appearance of
penile parenchyma, including presence of calcifications, cysts, masses, etc.
2. Measure diameter of right and left
cavernosal arteries on sagittal scan.
3. Obtain spectral wave forms of flow in
each cavernosal artery in sagittal plane.
4. Radiologist injects 1 cc (mi)
Prostaglandin into one of the corporal cavernosus at
the penile base.
5. Obtain pulsed Doppler patterns of each
cavernosal artery at 5, 10, 15, 20 and 25 minutes after administration of
Prostaglandin, checking with radiologist to see when study can be completed.
6. If there is no sign of tumescence in 25
minutes, a second penile injection of 1 cc Prostaglandin E-1 may be given.
7. Check patient for evidence of priapism
prior to him leaving the department. In
the event of concern regarding priapism, call emergency medicine physician and
refer patient to EU.
Evaluation of Dialysis Fistulas
1. No
patient preparation necessary.
2. Obtain
complete history. Obtain as detailed a
history of the fistula to be examined as possible. In synthetic material involved (a bridge
graft) or is there a native arterial/venous fistula? Have there been problems performing dialysis
or is there an abnormality on clinical examination? Grafts are often revised - has there been
previous surgical/radiologic intervention?
3. Imaging
is usually performed using a 7.5-10 MHz transducer.
4. Follow
the path of blood flow and examine the following segments:
a. The
feeding artery
b. The
first anastomosis which will either be directly to a native vein or to a
segment of synthetic material which will bridge the artery to the vein.
c. The
bridging graft, if present
d. If
there is synthetic material, examine the second anastomosis to the draining vein
e. Continue
examination of the venous side of the fistula to include examination of the
native subclavian vein, assuring good drainage.
f. Evaluate
for a steal by determining the direction of flow in the native artery distal to
the fistula (i.e.. radial and ulnar if a brachial
fistula
5. Examine
each segment of the graft (a-f) in sagittal and transverse planes using color
and Duplex Doppler. Record an angle
corrected velocity from each segment a-f and label the location appropriately.
6. Examine
each anastomosis and look for areas of narrowing, focal areas of high velocity,
or any change from the expected high velocity, low resistance waveform. Record any site of flow disturbance in color,
with labeled duplex Doppler image in sagittal plane.
7. Document
any perivascular masses in transverse and long axis. Use color to determine if there is pseudoaneurysm formation.
Perivascular fluid collections may signify infection.
Diagnostic Criteria for Dialysis
Fistulas:
1. Flow
within the feeding artery and throughout the synthetic bridge portion of the
graft should be monophasic with peak systolic
velocities of 100-400 cm/sec and end diastolic velocities of 60-200 cm/sec.
2. There
may be a slight increase in velocities at the arterial anastomosis due to
tapering of the graft.
3. The
draining veins demonstrate arterial pulsations with PSV of 30-100 cm/sec. Whether or not there is stenosis or
obstruction of the native subclavian vein will affect function of the graft and
this should be noted as an abnormal dampening of venous pulsations in the
subclavian.
4. Also
of interest is whether or not the direction of the flow in the artery distal to
the graft is reversed, producing a steal which may necessitate banding of the
fistula to restore flow in the distal artery.
Reference:
1. Duplex and color
Doppler sonography of hemodialysis and arteriovenous fistulas and grafts. RadioGraphics 1993;13:983-999.
Mesenteric Ischemia Protocol and Diagnostic Criteria
1. Fasting
Examination
a. Evaluate
the origins of the celiac and superior mesenteric arteries (SMA) with color and
duplex. Look for plaque, jets, post stenotic dilatation.
Obtain pulsed Doppler angle corrected velocities from the origins of the
SMA and celiac. Obtain angle corrected
aortic velocity at the level of the origins of celiac and SMA. In order to identify median accurate ligament
syndrome, evaluate the celiac in expiration and quiet breathing, which is when
the ligament causes obstruction.
b. Criteria
for stenosis:
Use peak systolic velocity
(PSV) and ratio of artery/aorta:
Celiac stenosis > 50% = PSV > 250 cm/sec and ratio >
3.5
SMA
stenosis > 50% = PSV > 200 cm/sec
and ratio > 3.5
c. Fasting
waveform should show high resistance in the SMA. If there is high diastolic
flow, suspect SMA disease.
2. Postprandial
examination (relies upon adequate food intake)
a. Repeat
angle corrected velocity measurements in the SMA at 15 through 30 minutes after
ingestion of a balanced meal (fat, carbohydrate, sugars).
b. Criteria for disease:
i. Normal response is an increase in PSV
and a 2-3 times increase in diastolic flow.
Response will vary with the caloric intake. If the caloric intake is not adequate, there
will be little or no response.
3. Both the SMA and celiac must be abnormal
to attribute symptoms to mesenteric ischemia.
See "Reference" page -
reference #15
References
1.
2. Dorfman GS, Cronan JJ: Venous ultrasonography. Radiol Clin North Am 30(5):879, 1992.
3. Katzen BT: Current
status of intravascular ultrasonography.
Radiol Clin North Am
30(5):895, 1992.
4. Robinson
ML: Duplex sonography of the carotid
arteries. Semin
Roentgenol 27(1):17, 1992.
5. Sacks
D: Peripheral arterial duplex
ultrasonography. Semin
Roentgenol 27(1):28, 1992.
6. Cronan JJ:
Ultrasound evaluation of deep venous thrombosis. Semin Roentgenol 27(1):39, 1992.
7. Zierler RE: The role
of the vascular laboratory in clinical decision-making. Semin Roentgenol 27(1):63, 1992.
8. Polak JF: Arterial
sonography: Efficacy for the diagnosis
of arterial disease of the lower extremity.
AJR 161:235-243, 1993.
9. Foley
WD: Color Doppler Flow Imaging.
10. Zwiebel WJ: Color
duplex US of the carotid arteries:
Technique, normal features, and technical pitfalls. In:
Rifkin MD, Charboneau JW, Laing
FC (Eds): Syllabus Special Course: Ultrasound 1991.
11. O'Leary
D, Glagov S, Zarins CK, Giddens DP: Carotid artery: Disease.
In: Rifkin MD, Charboneau JW, Laing FC (Eds): Syllabus Special Course: Ultrasound 1991.
12. Needleman
L: Peripheral venous US. In:
Rifkin MD, Charboneau JW, Laing
FC (Eds): Syllabus Special Course: Ultrasound 1991.
13. Polak JF: Peripheral
arterial sonography. In: Rifkin MD, Charboneau
JW, Laing FC (Eds):
Syllabus Special Course: Ultrasound
1991.
14. Hunink MGM, Polak JF, Barlan MM, O'Leary DH: Detection and quantification of carotid
artery stenosis: Efficacy of various Doppler
velocity parameters. AJR 160:619-625,
1993.
15. Flinn LR, Rizzo RJ:
Duplex scanning for assessment of mesenteric ischemia. Surg Clin North Am 70:99-107, 1990.