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20 Section 2: Vascular Laboratory
Correct Answer C Power Doppler imaging
Reference
Moneta, G. L., Yeager, R. A., Antonovic, R., et al. (1992). Accuracy of lower extremity arterial duplex
mapping. J Vasc Surg, 15(2), 275–283; discussion 283–274. PMID: 1735888
9. RATIONALE
Certain clinical situations, such as contralateral carotid occlusion, are associated with
increased compensatory flow in the ipsilateral ICA resulting in overestimation of the degree
of stenosis. In the presence of excessive tortuosity of the ICA, there is difficulty in insonating the artery at a 60-degree angle. Carotid plaque calcification results in certain areas of
the vessel being hidden, which may be the most stenotic with underestimation of the degree
of stenosis. The presence of tandem carotid lesions causes decreased flow due to proximal
lesions or increased resistance with distal lesions. In cases of proximal brachiocephalic or
proximal CCA lesions, the waveforms in the distal CCA and ICA can be dampened and have
a delayed systolic rise time or a low slope-to-peak systole as compared to the contralateral
side, leading to underestimation of the stenosis. In cases of significant distal disease in the
ICA, the waveforms can become more of a high-resistance signal, where there is a sharp
systolic rise time and significant reduction in diastolic flow that can go down to zero in cases
of distal ICA occlusion. Decreased cardiac output may result in dampening of the waveforms
on both sides. The presence of hypertension or tachycardia may result in increased pulsatility in the absence of carotid stenosis. Diffuse cerebrovascular disease may result in bilateral
high-resistance waveforms in the absence of cervical disease. The presence of an intimal
flap in a patient with spontaneous or traumatic ICA dissection can be easily diagnosed on
carotid duplex study.
Correct Answer D Detection of intimal flap
Reference
El-Sayed, H. F., Mouawad, N. J., Satiani, B. (2018). Noninvasive vascular lab testing for carotids, ver-
tebrals and transcranial Doppler. In S. S. Hans (Ed.), Extracranial carotid and vertebral artery
disease: contemporary management (pp. 68–83). Cham, Switzerland: Springer Verlag.
10. RATIONALE
MRA is the only vascular imaging technique that can be performed without the injection of contrast media—a technique referred to as time-of-flight (TOF) MRA. In contrast to routine MRI,
TOF MRA expresses a signal from stationary tissues instead of using the movement of blood
in the lumen of the blood vessels to create a signal referred to as flow-related enhancement. In
order to isolate f low in the arteries, venous flow enhancement is excluded by the use of saturation bands above the imaging volume, thus saturating flow from the cranial to caudal direction.
TOF MRA can be performed using both 2D and 3D acquisition modes. An advantage of the 2D
mode is a shorter imaging time and better sensitivity to slow flow, and it can visualize long segments of blood vessels. The disadvantages include decreased sensitivity to in-plane flow and
decreased special resolution. A stair-step artifact worsened by patient motion can be seen. 3D
TOF MRA is more commonly used to evaluate the head and circle of Willis and a smaller area
where imaging is needed. In addition, 3D TOF MRA has superior resolution. Disadvantages
include insensitivity to slow flow and longer acquisition time.
Section 2: Vascular Laboratory 21
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Contrast-enhanced MRA (CE MRA) relies on an intravascular contrast agent to directly
generate a signal within the vessel lumen. CE MRA is able to acquire the same imaging volume in a shorter period of time using a single breath-hold, even for imaging a larger field.
CE MRA is also acquired in the coronal plane, so that aortic arch disease can be assessed.
CE MRA is more accurate than TOF MRA in the settings of slow-flow or high-grade stenosis, which can be overestimated with TOF MRA. TOF MRA is not limited in the setting of
vascular calcification and should be preferred when calcification limits duplex imaging or
CTA. Phase contrast MRA, a non-contrast imaging technique, is more often used for MR
venography.
Correct Answer B Use of contrast medium is not necessary
Reference
Brott, T. G., Halperin, J. L., Abbara, S., et al. (2011). 2011 ASA/ACCF/AHA/AANN/AANS/ACR/
ASNR/CNS/SAIP/SCAI/SIR/SNIS/SVM/SVS guideline on the management of patients
with extracranial carotid and vertebral artery disease: executive summary: a report of
the American College of Cardiology Foundation/American Heart Association Task Force
on Practice Guidelines, and the American Stroke Association, American Association of
Neuroscience Nurses, American Association of Neurological Surgeons, American College of
Radiolog y, American Society of Neuroradiology, Congress of Neurological Surgeons, Society
of Atherosclerosis Imaging and Prevention, Society for Cardiovascular Angiography and
Interventions, Society of Interventional Radiology, Society of NeuroInterventional Surgery,
Society for Vascular Medicine, and Society for Vascular Surgery. J Am Coll Cardiol, 57(8),
1002–1044. PMID: 21288680
11. RATIONALE
Selective catheter-based arteriography using digital subtraction angiography (DSA) remains
the gold standard in cerebrovascular imaging. Selective catheter-based DSA imaging of the
cerebral vascular circulation is an invasive technique and carries a small risk (<1%) of neurological complications. CTA is performed following the rapid intravenous infusion of iodinated contrast with proper bolus timing to obtain an accurate assessment. CTA is obtained in
the axial plane, and these axial images can be reformatted in the coronal and sagittal planes.
Advanced postprocessing techniques allow for acquisition of 3D volume and surfacerendered images as well as segmentation techniques helping to isolate vessels from surrounding structures like bone and soft tissues. CTA allows for evaluation of the vessel
lumen and vessel wall along with visualization of surrounding anatomical structures.
Disadvantages include potential risk of contrast and exposure to ionizing radiation and
preparation with steroids and antihistamines in patients with iodinated contrast allergies.
Appropriate timing of imaging in relationship to the contrast bolus administration can be
affected by cardiac output, speed of CT the scanner, and blood volume status of the patient.
This may result in a lower-quality examination.
Correct Answer B Better resolution than MRA
Reference
Lell, M., Fellner, C., Baum, U., et al. (2007). Evaluation of carotid artery stenosis with multisection CT
and MR imaging: influence of imaging modality and postprocessing. AJNR Am J Neuroradiol,
28(1), 104–110. PMID: 17213434
22 Section 2: Vascular Laboratory
12. RATIONALE
Posterior circulation strokes account for 15%–20% of all strokes, and 20%–25% of those are due
to vertebral artery occlusive disease. Evaluation of the vertebral arteries is most challenging
by CTA, MRA, and DUS due to their smaller size. One-half of patients will present initially with
stroke, and 26% of patients present with TIA symptoms followed by stroke in a rapid fashion.
The mortality associated with posterior circulation stroke is 20%–30%, which is much higher
than an anterior circulation ischemic event. Up to one-third of vertebrobasilar ischemic episodes are caused by embolization from a plaque or mural lesions of the subclavian, vertebral,
and basilar arteries.
The most common site of disease is at the origin of the vertebral artery that may not be well
imaged by DUS or MRA. The best imaging modality for evaluation of vertebral disease is
catheter-based angiography using the DSA technique in an oblique projection.
Correct Answer A DSA
Reference
Berguer, R., Flynn, L. M., Kline, R. A., & Caplan, L. (2000). Surgical reconstruction of the extracranial
vertebral artery: management and outcome. J Vasc Surg, 31(1 Pt 1), 9–18. PMID: 10642704
13. RATIONALE
Lower extremity CT angiography (CTA) is indicated in the evaluation of peripheral arterial
disease (PAD), trauma, congenital malformation, vasculitis, arterial variants, and surgical
or endovascular planning. Three phases of imaging are generally performed: Precontrast
imaging, arterial phase imaging, and venous delayed phase imaging. Arterial phase imaging
is performed typically with either a fixed scan delay or bolus tracking. A fixed scan delay of 40
seconds enables imaging to automatically commence after the delay. Bolus tracking relies on
achieving a predetermined attenuation (usually 100–120 Hounsfield units) within the area of
interest in the infrarenal aorta, and imaging is initiated after a fixed time period. Typically, 100
cc of iodinated contrast is used, but this quantity may be increased to image larger patients or
diminished if the patient is scanned on newer equipment with a faster speed table. Lowering
the X-ray tube voltage and increasing the pitch with a helical CT scan decreases radiation
exposure. Three-dimensional postprocessing with maximum intensity projection (MIP) multiplanar reformatted, 3D VR images and shaded surface displays can be used to augment analysis of the reconstructed cross-sectional axial images. Imaging the entire course of the vessel
in a single plane (centerline) is useful in evaluating vascular density and planning for sizing of
the endografts. In the presence of arterial calcification, the evaluation of arterial stenosis does
compromise diagnostic accuracy with limited spatial resolution of CT, with partial volume
averaging of different densities in a single voxel and high-density calcification increasing the
density of tissues within the same voxel and adjacent voxels. This can exaggerate the size of
the calcified plaque, causing a blooming artifact. Use of dual-energy CT (DECT) allows for the
automatic reduction of CT luminograms by removing calcium and bone.
Correct Answer A Less contrast and lower radiation exposure
Reference
Ofer, A., Nitecki, S. S., & Linn, S., et al. (2003). Multidetector CT angiography of peripheral vascular
disease: a prospective comparison with intraarterial digital subtraction angiography. AJR Am J
Roentgenol, 180(3), 719–724. PMID: 12591682
Section 2: Vascular Laboratory 23
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14. RATIONALE
The normal response to exercise is either no change or an increase in the ABI following
exercise. A reduction in the ABI following exercise indicates the presence of arterial occlusive disease. The greater the decrease in ABI, the more severe the disease. The recovery
time to baseline ABI also provides information about the disease; if the recovery time is
more than 12 minutes, multilevel disease is more likely. The treadmill test tends to be more
positive with proximal disease since the aortoiliac vessels supply all the musculature of the
lower extremities such as large gluteal muscles and muscles of the thigh, so that the effect
of lesions in aortoiliac vessels is greater than those with isolated occlusion of the inferior
femoral arteries. Exercise testing is not of any value for the diagnosis of infrapopliteal artery
occlusive disease.
Correct Answer A Multilevel
Reference
Stein, R., Hriljac, I., & Halperin, J. L., et al. (2006). Limitation of the resting ankle-brachial index in
symptomatic patients with peripheral arterial disease. Vasc Med, 11(1), 29–33. PMID: 16669410
15. RATIONALE
A dampened waveform with a delay to peak systole, also referred to as tardus parvus, in the
common femoral artery is suggestive of significant proximal stenosis or occlusion (aortoiliac).
This phenomenon is observed downstream to the site of stenosis and is the result of the magnitude of blood flow to the narrowed vessels during ventricular systole. This characteristic pattern
is also useful in assessing for renal artery stenosis.
Correct Answer C Aortoiliac occlusive disease
Reference
H., K., Jabaz, D. F., & Weerakkody, Y., et al. (2023, 1/20/2023). Tardus Parvus. Retrieved from h tt ps ://
radiopaedia.org/articles/tardus-parvus?lang=us
16. RATIONALE
In a normal artery, blood flow velocity and the pressure do not show any significant change. In
the presence of hemodynamically significant stenosis within an artery, the pressure gradient
increases across the segment of stenosis. There is an increase in the velocity of the blood flow
within the stenosis. There is turbulent flow past the area of stenosis, resulting in a decrease in
pressure distal to the stenosis as compared to the pressure proximal to the stenotic segment.
This pressure change is referred to as the pressure gradient. The absolute value of blood pressure at this point is not relevant to blood flow.
Correct Answer D An increase in the velocity at the site of stenosis and increased pressure
gradient across the stenotic segment
24 Section 2: Vascular Laboratory
Reference
Pellerito, J. (2019). Doppler flow imaging and spectral analysis. In Introduction to vascular ultrasonog-
raphy E-book (pp. 56–84). Elsevier Health Sciences.
17. RATIONALE
A 7–12-MHz linear transducer is used to evaluate hemodialysis access. 2D gray-scale images,
color Doppler images, pulse-wave spectral Doppler waveforms, volume flow measurements,
and peak systolic velocity measurements are obtained. Volume fluid is calculated by the ultrasound machine. Diameter measurement is required to determine the area, and pulse-wave
spectral Doppler measures the time averaged mean velocity.
Volume flow in the fistula equals the time average velocity multiplied by the area multiplied by
60, where area is the cross-sectional area of the vessel in square centimeters (since the vessel is
cylindrical, its section is a circle whose area is calculated as the square of the radius.
Findings in normal hemodialysis access include:
1. Peak systolic velocity (PSV) between 150 and 300 cm/s
2. High diastolic flow with low-resistance waveform
3. High volume flow (greater than 500 mL/min)
Low volume flow (less than 500 mL/min) is indicative of severe stenosis. A focal increase in
PSV >100% indicates severe stenosis, and these two findings may necessitate a fistulogram.
Correct Answer D Greater than 800 mL/min
Reference
Gaiser, R., & Fox, T. B. (2016). Vascular technology examination PREP (1st ed.). New York: McGraw-Hill.
18. RATIONALE
When interpreting the segmental systolic limp pressures of the extremities, the following criteria are utilized to consider if the examination is normal:
1. Equal to or less than 30 mmHg difference between any two adjacent lower limb segmental
systolic pressures
2. High thigh systolic pressure recordings equal to or greater than 30 mmHg above the higher
brachial systolic pressure
In general, if the high thigh pressure is 30 mmHg or less when compared to high brachial pressure, this is indicative of iliac artery occlusive disease, and if similar findings are present on
both sides, it may indicate bilateral iliac or aortic (infrarenal) stenosis. If the pressure gradient is
30 mmHg or higher between the thigh and calf, it indicates femoral-popliteal disease and between
the calf and ankle indicates infrapopliteal disease. Pulse volume recordings (PVRs) are performed
using the same cuffs as the segmental pressures, so the PVR waveforms are acquired at the same
levels. PVR waveforms represent the entire amount of perfusion through the underlying segment
of the limb, including collateral flow. PVR waveforms cannot distinguish between collateral flow
and regular flow, with the possibility of underestimating the severity of the disease. PVR waveforms are not inf luenced by cuff artifact or arterial calcification, thus making them more reliable
Section 2: Vascular Laboratory 25
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in arterial flow assessment. A cuff artifact may occur when the width of the blood pressure cuff is
either too large or too small for the limb. If the width of the cuff is less than 20% of the limb diameter, it will result in a falsely elevated peak systolic pressure. If the width of the cuff is too large, it
can result in a peak systolic pressure that is artificially lower.
Correct Answer C In patients with calcified arteries
Reference
Gaiser, R., & Fox, T. B. (2016). Vascular technology examination PREP (1st ed.). New York: McGraw-Hill
19. RATIONALE
Pulse-wave (PW) spectral Doppler should be used to identify and quantify flow reversal in the
caudal direction following distal compression. The normal response of blood flow in the deep
and superficial veins following distal compression should have no reversal of blood f low or very
little reversal. When the reversal of blood flow exceeds 0.5 second in the standing position, it is
considered significant for venous reflux. Some literature suggests that for deep venous reflux, it
should be 1.0 second because of the larger size of the deep veins. The extended reversal of blood
flow that occurs when the distal compression is released is considered significant and a positive sign for venous insufficiency. Venous reflux can also be evaluated by performing proximal
compression or having the patient perform a Valsalva maneuver. The normal response should
be cessation of flow followed by augmentation and resumption of flow in the correct (cephalad)
direction upon release. When venous reflux is present, there will be a reversal of blood flow
(caudal direction) and the normal cephalad direction will be resumed when released.
Correct Answer B >0.5 second
Reference
Gaiser, R., & Fox, T. B. (2016). Vascular technology examination PREP (1st ed.). New York: McGraw-Hill
20. RATIONALE
On spectral analysis, the veins that are farther away from the heart will have waveforms like
that of the lower extremity. Veins with spontaneity, augmentation in response to distal compression, and with phasic flow as demonstrated in the axillary, basilic, and brachial veins. The veins
closer to the heart such as internal jugular; brachiocephalic (difficult to insonate); and subclavian veins demonstrate cardiac pulsations and respiratory patterns. Any change from each
vein’s normal waveform may be indicative of proximal obstruction. Lack of spontaneity and
phasicity indicates distal and proximal obstructions, respectively, for the veins farther from the
heart, as in veins of the lower extremity. A continuous waveform with loss of pulsatility in the
central veins is usually indicative of a proximal obstruction. That is the reason behind obtaining a venous study on both sides. If a normal pulsatile waveform is demonstrated in the right
subclavian vein and on the left side a phasic waveform with minimal pulsatility is seen, it may
suggest a proximal obstruction on the left side.
Correct Answer B An obstruction proximal to the right subclavian vein
Reference
Gaiser, R., & Fox, T. B. (2016). Vascular technology examination PREP (1st ed.). New York: McGraw-Hill
26 Section 2: Vascular Laboratory
21. RATIONALE
Mesenteric duplex imaging is typically performed with a low frequency (2–8 MHz) curvilinear
transducer in a fasting state (at least 8–10 hours). The study is repeated about 30 minutes after
eating a meal if the fasting waveforms are normal. Gray-scale images of the celiac axis, SMA,
and rarely IMA followed by color and spectral Doppler study is obtained. In a fasting state, the
celiac axis (main supply to the liver and spleen) has a low-resistance distal bed. The SMA should
have a high-resistance waveform due to constricted arterioles distally in the resting state. After
a meal, there is arteriolar dilatation to increase the blood supply to the intestines, with a change
to a low-resistance flow pattern with forward flow in all phases of the cardiac cycle. If in the
fasting state the SMA flow pattern is low resistance (monophasic), then a postprandial study
is not necessary, as distal arterioles are abnormally persistently dilated due to hypoxia. For a
diagnosis of mesenteric ischemia, velocity measurements are diagnostic. For the celiac artery,
normal peak systolic velocity is 50–160 cm/s, and peak systolic velocity greater than 200 cm/s
predicts 70% diameter stenosis. For the SMA, normal PSV (110–177 cm/s) with peak systolic
velocity greater than 275 cm/s predicts greater than 70% stenosis. If significant celiac axis stenosis/occlusion is suspected, the gastroduodenal artery should be imaged to evaluate for retrograde flow, as the gastroduodenal artery becomes an important collateral circulation source to
the liver and spleen via the pancreaticoduodenal arteries from the SMA in the presence of celiac
axis occlusion.
Correct Answer B Superior mesenteric artery stenosis
Reference
AbuRahma, A. F., Stone, P. A., Srivastava, M., et al. (2012). Mesenteric/celiac duplex ultrasound inter-
pretat ion criteria rev isited. J Vasc Surg, 55(2), 428–436.e426; discussion 435–426. PMID: 22195765
22. RATIONALE
The renal-to-aortic ratio is not accurate when the peak systolic velocity (PSV) of the aorta is less
than 40 cm/s or greater than 90–100 cm/s. Normal PSV is less than 180 cm/s at the origin, proximal, mid, and distal renal artery. PSV of greater than 180–200 cm/s along with post-stenotic
turbulence is suggestive of equal to or greater than 60% diameter reduction of the renal artery.
An abnormal resistive index (equal to or greater than 0.7) is indicative of renal artery stenosis;
the resistive index is calculated by PSV minus EDV divided by PSV. Acceleration time and index
are measured by calipers along the systolic slope. The normal acceleration time is less than
0.1 second. A delay in the acceleration slope, also known as tardus parvus, present as a rounding of the systolic peak, is suggestive of an obstruction proximal to the point of sampling.
Correct Answer D >3.5
Reference
Neumyer, M. M. (2000). Native renal artery and kidney parenchymal blood flow duplex examination
with and without color flow imaging. In C. Rumwell & M. McPharlin (Eds.), Vascular technology:
an illustrated review (pp. 101–103). Davies Pub.
23. RATIONALE
Duplex surveillance of the lower extremity bypass (femoral-popliteal/tibial) in conjunction with
ankle-brachial indices are extremely useful for detecting occult stenosis in the bypass. A 10- to
Section 2: Vascular Laboratory 27
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12-MHz or 5- to 7-MHz linear transducer is used depending on the type (vein or prosthetic) and
depth of the bypass. Duplex surveillance of the infrainguinal bypass includes 2D gray-scale
imaging, color Doppler images, and a pulse-wave spectral Doppler waveform with measurements of peak systolic velocity at the:
1. Inflow artery
2. Proximal anastomosis
3. Proximal bypass
4. Mid-bypass
5. Distal bypass
6. Distal anastomosis
7. Outflow artery
A significant stenosis manifests as doubling of the peak systolic velocity between the adjacent
segments and represents greater than 50% stenosis (hemodynamically significant). In addition,
there is evidence of post-stenotic turbulence just distal to the stenosis and a reduced peak systolic velocity value with a delayed rise farther distal to the area of stenosis. In patients undergoing in situ vein bypass reconstruction, there remains a possibility of a retained venous branch
resulting in an arteriovenous fistula.
Correct Answer D >50%–99% stenosis in the bypass
Reference
Tinder, C. N., Chavanpun, J. P., Bandyk, D. F., et al. (2008). Efficacy of duplex ultrasound surveillance
after infrainguinal vein bypass may be enhanced by identification of characteristics predictive
of graft stenosis development. J Vasc Surg, 48(3), 613–618. PMID: 18639428
24. RATIONALE
The cold immersion test is performed to confirm the diagnosis of primary Raynaud disease with intermittent symptoms of numbness and cold in response to cold temperatures
or stress in the fingers and, uncommonly, the toes. Areas of the skin turn white and then
blue. The digital arteries supplying the skin develop vasospasms, limiting blood flow.
Testing for primary Raynaud disease is completed by first obtaining digital photoplethysmogram (PPG) waveforms and pressures at rest in a normal-temperature environment
followed by immersion of the hands or feet in a basin of ice water for 1–3 minutes. Once
the hands and feet are taken out of the ice water, they are dried and digital waveforms and
pressures are obtained at 2 minutes, 5 minutes, and 10 minutes. Resting digital pressures
should be near 90% of the higher brachial pressure. The PPG waveform is normally
similar to the PVR waveform – a rapid upstroke, sharp peak, and a dicrotic notch. In
patients with:
1. Raynaud disease, a peak pulse waveform may be seen on the pre-immersion PPG waveform
where the dicrotic notch is higher than normal
2. Decrease in systolic pressure of greater than 20% pre-immersion
3. Waveform resumes pre-immersion waveform pattern within 5–10 minutes of being removed
from ice water
28 Section 2: Vascular Laboratory
In thoracic outlet syndrome, there is a reduction in flow in certain maneuvers as noted by the
PPG waveform. These maneuvers consist of:
A. Military position (palms facing forward and elbows posteriorly)
B. Overhead abduction of 180 degrees
C. Arms at 90 degrees abduction posteriorly
D. Adson maneuver with arms abducted out to the sides (90 degrees) with the head turned to
either side
Correct Answer B Primary Raynaud disease
Reference
Gaiser, R., & Fox, T. B. (2016). Vascular technology examination PREP (1st ed.). New York:
McGraw-Hill.
25. RATIONALE
The ability of native duplex ultrasound criteria to accurately predict ISR continues to be the
focus of further studies. It has been demonstrated that native vessel criteria overestimate the
degree of in-stent stenosis. Patients with superior mesenteric artery and celiac artery stents tend
to have an increased peak systolic velocity, and therefore native peak systolic velocity criteria
are unreliable for the determination of in-stent restenosis. The PSV criteria of ≥70% stenosis
is higher for ISR than for native visceral stenosis. The velocity criteria that define equal to or
greater than 70% in-stent restenosis of the SMA is equal to or greater than 445 cm/s and equal to
or greater than 289 cm/s for a stented celiac artery.
Correct Answer C <70% ISR of the celiac artery and SMA
Reference
Soult, M. C., Wuamett, J. C., Ahanchi, S. S., et al. (2016). Duplex ultrasound criteria for in-stent resteno-
sis of mesenteric arteries. J Vasc Surg, 64(5), 1366–1372. PMID: 27633165
26. RATIONALE
Progressively increasing PSV and ICA/CCA ratios correlate with in-stent restenosis within the
stented carotid artery. Receiver operating charateristic analysis demonstrated the following optimal threshold criteria: residual stenosis > 20% (PSV > 340 cm/s and ICA/CCA ratio > 4.15), in-stent
restenosis > 50% (PSV > 220cm/s and ICA/CCA ratio >2.7), and in-stent restenosis > 80% (PSV).
Correct Answer B Equal to or greater than 80% reduction
Reference
Lal, B. K., Hobson, R. W., 2nd, Tofighi, B., et al. (2008). Duplex ultrasound velocity criteria for the
stented carotid artery. J Vasc Surg, 47(1), 63–73. PMID: 18178455
27. RATIONALE
Conventional catheter-based arteriography is seldom necessary for the diagnosis of extracranial
dissection despite being the most sensitive diagnostic study because of its invasive nature. The
Section 2: Vascular Laboratory 29
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classic signs for dissection seen on neuroimaging are an enlarged artery with a crescent-shaped
rim of hyperintense signal from the hematoma that is surrounding the decreased lumen. In
41%–75% of cases, dissection may present with the radiographic “rat’s tail or string sign,” which
represents a tapered stenosis on neuroimaging. CTA has a high sensitivity and specificity; however, it is associated with radiation exposure and can pose a technical challenge in obtaining
the high-quality imaging of the vertebral arteries. CTA offers more advantages over MR angiography in visualization of the vertebral arteries due to bony artifacts on MRI being unable to
provide a clear visualization of the vertebral arteries. Catheter-based arteriography is unable to
visualize intramural hematomas.
Correct Answer B CTA
Reference
Debette, S., & Leys, D. (2009). Cervical-artery dissections: predisposing factors, diagnosis, and out-
come. Lancet Neurol, 8(7), 668–678. PMID: 19539238
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