A Physician's Guide to Transcranial Doppler Procedures

A Physician’s Guide to
Transcranial Doppler Procedures

Peripheral Vascular Lab, Orlando Health
Orlando Regional Medical Center
IAC Transcranial Doppler Acrreditation since 2016

Martin Menkin, MD
The Neurosonology Project

Orlando Health Physician’s Guide to TCD

TABLE OF CONTENTS

INTRODUCTION.......................................................................2
A BRIEF OVERVIEW OF TRANSCRANIAL DOPPLER...........................3
THE TRANSCRANIAL DOPPLER IMAGING TEST...............................4
THE DETECTION OF PFO TEST.....................................................6
THE DETECTION OF CEREBRAL EMBOLI TEST.................................8
VERTEBROBASILAR INSUFFICIENCY TESTS......................................8
THE CEREBROVASCULAR RESERVE TEST.........................................9
ORDERLY ORDERING................................................................11

1 | ORLANDO HEALTH

Orlando Health Physician’s Guide to TCD

Introduction of Insonnation.” In the 1990s, routine
interrogation of intracranial arteries became
Ultrasound is a safe, noninvasive tool. The possible using Transcranial Doppler.
early ultrasound technique, called B-Mode Approximately 10% of patients have poor
Scanning, defined anatomy. With Color Flow conduction of ultrasound at their Windows
Doppler, we added the ability to define flow of Insonnation. Transcranial Doppler may be
direction and velocity. With this addition, impossible in these individuals, or data may
Color Duplex Scanning became a tool be incomplete. Data acquisition may also be
to define the anatomy and physiology of reduced by limitations in patient positioning
vascular structures. or by patient movement.
Early applications of Color Duplex Scanning Advances in Ultrasound technology over
depended upon the ability of soft tissues to the last two decades have extended the depth
conduct ultrasound. Data from intracranial and breadth of data available by Transcranial
vessels was shielded from interrogation Doppler. This brochure is an effort to expand
by the cranial vault. In the 1980s, research understanding of TCD to those physicians
defined correct frequencies and algorithms to faced with a need for this data.
gain data from intracranial arteries through
anatomic portals of relatively satisfactory
ultrasonic conductivity. These areas of absent
or thin bone are referred to as “Windows

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Orlando Health Physician’s Guide to TCD

A Brief Overview of Transcranial Doppler

Transcranial Doppler Imaging (TCDI) uses Alternate studies can be considered.
B-mode Ultrasonography to define Arteriography, CT Angiography (CTA),
the anatomic location of an artery. The and MR Angiography (MRA) can provide
physics of Color Duplex Scanning define the similar data to that of TCD. However, TCD
speed and direction of flow of red blood cells information can be performed at bedside
in that artery. The ultrasound technologist in unstable patients. It can be repeated
saves sequentially acquired data in a color- daily without risk in patients with unstable
keyed “map” and detailed reproducible flow disease. TCD is not restricted in patients
data is obtained. intolerant to the MRI environment, or
TCD Imaging (TCDI) is the test many medically unsuitable for IV Contrast.
physicians think of as “TCD.” It can, for This manual discusses TCD tests individually
example, define the presence of velocity in the following pages.
increase at a site of stenosis or vasospasm,
or identify flow direction aberrations in
anastomotic networks. In recent years, TCD
applications have expanded to include: (1)
• T he Evaluation of Cerebrovascular

Reserve distal to ICA Stenosis
• A Protocol for the Detection of Patent

Foramen Ovale (PFO)
• A Protocol for the Detection of

Cerebral Emboli
• P rotocols for evaluating Vertebrobasilar

Insufficiency

References

1. International Journal of Vascular Medicine Vol 2013 (2013) Article ID 629378 Transcranial Doppler Ultrasound: A Review
of the Physical Principles and Major Applications in Critical Care Naqvi, J, et al

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Orlando Health Physician’s Guide to TCD

The Transcranial Doppler Imaging Test
(CPT 93886)

TCDI supplies data regarding location, flow ORTHOSTATIC BASILAR ARTERY
velocity, direction of flow as well as pulse INSUFFICIENCY
morphology within intracranial arteries.
The following is a list of Clinical Applications Flow velocity normally rises at the proximal
of TCDI, with a brief description of how basilar artery upon standing. But in some
we acquire the primary data of interest and individuals, standing produces symptoms of
how that data is applied to each clinical dizziness and moving from supine to sitting
circumstance. and then to standing produces a decline in
velocity at the Basilar Artery. This decline
INTRACRANIAL STENOSIS is a measure of clinically significant and
(in Atherosclerosis or Vasculitis) treatable orthostatic hypotension even in
those individuals who do not demonstrate
Velocity will be elevated at sights of segmental a concurrent orthostatic decline in blood
stenosis. Stenosis can be localized, quantified pressure measured at the brachial artery.
and followed over time.
ROTATION-INDUCED BASILAR
VASOSPASM (in Subarachnoid ARTRY INSUFFICIENCY
Hemorrhage or Head Trauma) (Bow Hunter’s Syndrome)

Velocity will be elevated at segments of Velocity in the Basilar Artery system should
vasospasm. Monitored day to day, these be unchanged with head rotation even in
increases can reveal worsening patterns days those individuals with rotation-induced
before clinical signs of worsening emerge, Vertebral Artery occlusion. This is due to
permitting early therapy. (1) sufficient retained flow from the contralateral
Vertebral Artery. TCD can reliably find
SICKLE CELL DISEASE reduced velocity at the posterior cerebral
artery with far left or far right head rotation
Velocity may be elevated in a fashion similar in those individuals with rotation-induced
to that seen in vasospasm. Velocity elevations Vertebral Artery occlusion who do not have
persistantly above those defined in the STOP sufficient contralatral flow. This rare but
Criteria are associated with an elevated risk treatable cause of dizziness and syncope is
of stroke. This risk is reduced by the prudent difficult to diagnose by alternate means.
use of transfusion. Children are generally
studied yearly, but more often if indicated by
worsening velocity patterns. (2)

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Orlando Health Physician’s Guide to TCD

SUBCLAVIAN STEAL SYNDROME CEREBRAL CIRCULATORY ARREST

Flow direction in the Vertebral Artery Pulse “morphology” refers to the shape
is normally cephalid. Carotid Duplex of the pulse wave from early systole to
Scanning can confirm this in the cervical end-diastole. A flat line morphology in
vertebral segments and TCD can a technically satisfactory study implies
confirm this in the distal intracranial absent perfusion if the patient has
vertebral segments. Either test might previously demonstrated measurable flow
reveal bidirectional flow or reversal of (Windows of Insonnation have previously
flow patterns if stenosis exists in the been demonstrated to be adequate). A
chest vessels proximal to the origin of reverberating or low volume to-and-fro
the Vertebral Artery. These abnormal morphology, or an early systolic peak
patterns can sometimes be unmasked by with no flow in diastole heralds
“Hyperemic Testing” (release of BP cuff circulatory arrest.
previously inflated above systolic pressure
ipsilateral to the Vertebral Artery
being tested).

References

1. N eurosurg Clin N. Am 2010 Role of Transcranial Doppler in the Diagnosis and Management of Vasospasm after
Aneurysmal Subarachnoid Hemorrhage Marshall SA, et al

2. Blood 2004; 103: 3689-3694 Stroke and Conversion to High Risk in Children Screened with Transcranial Doppler
Ultrasound During the STOP Study Adams, RJ, et al

3. I SRN Critical Care 2013 Article ID 167468 (6 pages) Transcranial Sonology and Cerebral Circulatory Arrest in Adults:
A Comprehensive Review Llompart-Pou, JA ,et al

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Orlando Health Physician’s Guide to TCD

The Detection of PFO Test (CPT 93893)

Due to the distinct acoustic signature of bubbles, • Devices for percutaneous closure are
Transcranial Doppler can indentify and count approved by the FDA.
the bubbles traversing the MCA.
• The role of percutaneous closure is viewed as
When aggitated saline rich in bubbles is injected unsettled science by some experts. There is a
into a brachial vein, bubbles arrive at the right broad consensus to address closure if there is
atrium in 10 seconds and then safely moves a recurrent stroke while on Aspirin therapy.
through the right heart to the pulmonary Debate regarding percutaneous closure of
vasculature where they are absorbed. If there is PFO is especially active regarding whether
an atrial septal defect (most common being a or not benefit can be found in older patients
PFO), some bubbles may be shunted from the or in those with alternate risk factors for
right atrium to the left atrium, and over the next stroke. (5, 6)
10-60 seconds some may find their way to a
Middle Cerebral Artery (MCA). The TCD Protocol for Detection of PFO is a
bedside study which can be done without delay
The Protocol for Detection of PFO interrogates in hospitalized patients. It is most informative
the MCA bilaterally during intervals with in a patient who is able to perform the Valsalva
normal respirations and intervals which begin Maneuver. Early detection permits the diagnosis
with Valsalva Maneuver. A Valsalva Maneuver to be part of the early clinical dialogue and may
enhances pressure gradients that favor right-to- shorten length of stay.
left shunting. Bubbles traversing the bilateral Outpatient studies are readily performed with
MCAs are counted for one- minute intervals. a simple IV site and do not require the sedation
Test results are reported as Grade 0 through 5 and endoscopy of TEE.
based on the total number of bubbles. Grades 3 The TCD PFO Protocol has a high positive and
through 5 are of increasing clinical significance. negative correlation with results obtained by
Transesophageal Echocardiogram (TEE) with
Approximately 20% of the population Bubble Study. It is superior to Transthoracic
demonstrates a PFO. It is often asymptomatic, Echocardiogram (TTE) with Bubble Study. (7)
however: TCD cannot diagnose left atrial appendage clot.
• Paradoxical embolism via PFO is viewed as a PFO is present in approximately
20% of the population. Most cases are clinically
common cause of Cryptogenic Stroke (CS) in silent. Intervention can be appropriate but
individuals under the age of 55 years. (1, 2) demands informed clinical judgment.
• There is evidence that the benefit for stroke
risk reduction of percutanious closure of a
PFO exceeds that of Aspirin therapy. (3, 4)

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Orlando Health Physician’s Guide to TCD

References

1. A RYA Atheroscler. 2011 Summer; 7(2): 74-7 Evaluation of Patent Foramen Ovale in Young Adults with Cryptogenic Stroke
Hossein Ali Ebrahimi, et al

2. NEJM 2016; 374 2065 - 2074 May 26, 2016 Cryptogenic Stroke Saver, Jeffery l
3. h ttp://www.acc.org/latest-in-cardiology/clinical trials/2017/ 09/14/11/45/close Patent Foremen Ovale Closure or

Anticoagulants versus Antiplatelet Therapy to Prevent Stroke Recurrence-CLOSE Bavry, Anthony
4. N EJM 2017; 377: 1011-21 Patent Foramen Ovale Closure or Anticoagulation vs Antiplatelets After Stroke Mas JL et al 5.

Stroke 2017 45:A73 Abstract 73: Risk of Paradoxical Embolism (ROPE) Score Stratification of Pooled Pfo Closure Clinical
Trial Data Thaler, DE , et al
6. NEJM 2017 Sep 14:377(11) 1093-1095 Tipping Point for Foramen Ovale Closure, Roper AH
7. JACC: Cardiovascular Imaging Vol 7 (3) 2014 pages 236-250 Accuracy of Transcranial Doppler for the Diagnosis of
Intracardiac Right-to-Left Shunt Mojadidi, M Khalid, et al

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Orlando Health Physician’s Guide to TCD

The Detection of Cerebral Emboli Test (CPT 93892)

This is a protocol in which TCD interrogation This study will potentially detect a proximal
is performed continuously over the bilateral source of emboli to the MCA. If emboli are
MCA. The patient is resting supine with detected bilaterally, a cardiac source such
normal respirations for this 60-minute passive as mural thrombus, valvular disease, ASD
interrogation. or atrial appendage clot can be considered.
Particulate Emboli have a distinctive Unilateral particulate emboli would favor an
Acoustic Signature, or “chirp,” which is easily ipsalateral carotid plaque as the site of origin.
distinguished from the echo of flowing red False positive studies are rare. The degree of
blood cells. The number of emboli can be easily false negatives is poorly defined. A negative
counted. There should be zero under normal study in a clinical circumstance which favors
circumstances. embolic disease might lead to the consideration
of a second 60-minute interrogation.

Vertebrobasilar Insufficiency Tests (CPT 93882)

Vertebrobasilar Insufficiency (VBI) can be SUBCLAVIAN STEAL SYNDROME
an ambiguous term. Any drop in the mean
arterial pressure could include insufficient The direction of flow in one Vertebral
posterior circulation perfusion, with an Artery (VA) becomes either episodically or
associated decline in vision or balance or continuously retrograde, sending blood to
a reduction in full alert function. This set the ipsalateral arm instead of cephalid to
of TCD protocols evaluates patients with the posterior fossa structures. This is usually
episodic VBI in the absence of recognized the consequence of proximal subclavian
orthostatic hypotension, cardiac arrythmia, artery stenosis ipsalateral to the steal and
middle ear pathology, or other systemic occurs with arm use or posture. This can
cause for VBI-type symptoms. be evaluated either by Carotid Dopler or
These clinical applications are also TCDI The flow morphology on a Color
covered in the TCDI Chapter, pages 4-5. Duplex Scan of the cervical VA, or on a
TCD defines velocity changes or flow TCDI interrogation of the Intracranial VA
direction changes that can be applied to the might be notched, bidirectional or reversed
following clinical presentations of VBI. giving sufficient evidence for the diagnosis.
Uncertain cases will sometimes show a
8 | ORLANDO HEALTH defined reversal of flow in the VA only
when a blood pressure cuff, inflated above
systolic on the ipsalteral arm, is deflated and
the increase blood flow to the arm provokes
VA flow reversal.

Orlando Health Physician’s Guide to TCD

VERTROBASILAR ORTHOSTASIS ROTATION-INDUCED VERTEBRAL

Some patients who show a clear pattern ARTERY OCCLUSION (CPT 93886)
of orthostatic dizziness have no evident
orthostatic change on brachial blood (Bow Hunter’s Syndrome)
pressure, but do show an orthostatic decline
in proximal Basilar Artery (BA) flow. The Head rotation to the far right or left, as in
proximal BA is interrogated supine, seated hunting with a bow, will produce ipsalateral
and standing. We define a 30% or greater vertebral blockage in 30% of individuals.
A small percentage of these people will
decline in velocity as a positive study (there experience VBI. The TCD Protocol for this
are no national data for this study). BA flow is to first establish that the P2 segment of the
velocity should rise upon standing under Posterior Cerebral Artery (PCA) takes origin
normal circumstances. from the distal Basilar Artery (TCDI test
demonstates intact P1 segment PCA). The
P2 segment of the PCA is then interrogated
with head turn fully to the right and then
to the left, seeking to identify a decline in
flow velocity.

The Cerebrovascular Reserve Test (CPT 93890)

Stroke risk in properly selected individuals blood flow in the Middle Cerebral Artery
can be reduced by Carotid Endarterectomy (MCA) at rest and then after a vasodilatory
(CEA) or Carotid Artery Stenting (CAS). stimulus (see below). It identifies the presence
Selection criteria often focus on the degree or absence of the MCA to reactively reduce
of Internal Carotid Artery (ICA) stenosis, vascular resistance and thereby maintain flow
the presence or absence of TIA, patient age, in response to reduced perfusion pressure
intercurrent illnesses, and projected risk of or reduced O2 saturation. (2) A response is
the intervention. either Impaired or Unimpaired. An Impaired
The addition of a physiological parameter, Response is associated with a higher
Cerebrovascular Reserve (CVR), adds a cost- stroke risk.
effective tool for informing clinical decisions CVR does not directly correlate with the
regarding revascularization procedures. (1) degree of ipsalateral Internal Carotid Artery
CVR is a measure of the ability (or lack (ICA) stenosis. The MCA distal to a severe
thereof) of the MCA to dilate when necessary. ICA stenosis might be anticipated to be dilated
Transcranial Doppler evaluation of at rest and show little incremental dilatation
Cerebrovascular Reserve (CVR) measures when challenged with a CVR stimulus (an
Impaired Response). However, variance in
intracranial anastomotic supply to an MCA

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Orlando Health Physician’s Guide to TCD

may introduce perfusion opportunities Breath-holding Protocol which generates a
unrelated to the ipsalateral ICA. Therefore, mathamatically-derived Breath-holding Index
a vessel distal to a severe ICA stenosis could (BHI). BHI below .60 is considered to be an
show a robust vasodilatory reserve above impaired CVR with increased stroke risk. (3)
resting baseline when stimulated to do so (an Patients must demonstrate the ability calmly
Unimpaired Response). hold their breath for 30 seconds. Alternate
CVR identifies the dynamic perfusion status protocols are under evaluation.
of the MCA, and is therefore informative Data for CVR is interpreted in the context
regarding stroke risk. of TCDI data, and both studies are therefore
There as several techniques used to stimulate done. If a Carotid Doppler has not been done
a vasodilatory response, including injection in 12 months or is not available, Color Duplex
of Diamox, Inhalation of CO2, and breath- Scanning of the Carotids will also be part of
holding. At the present time we are using a this evaluation.

References

1. R adiology Feb 2015 274(2) 455-463 Carotid Artery Stenosis: Cost-effectiveness of Assessment of Cerebrovascular Reserve to
Guide Treatment of Asymptomatic Patients Ankur Pandya, et al

2. D igitalCommons.unl.edu/ucareresearch/89 University of Nebraska-Lincoln 2016 Analysis of Breath-holding Index as an
Assessment of Cerebrovascular Reactivity Porter, Allison P et al

3. R ev Neurol Nov 2006 16-30 Normal Values of Cerebral Vasomotor Reactivity Using the Breath-holding Test Jimenz-Caballero,
PE, et al

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Orlando Health Physician’s Guide to TCD

Orderly Ordering

Office staff who order studies through Central Scheduling are familiar with the phone
numbers listed below. Patients who are asked to call and schedule their own Carotid or
TCD Studies will find this helpful.

At the present time, all outpatient TCD Studies are performed at the Peripheral Vascular
Lab at Orlando Regional Medical Center. Carotid Doppler Studies are done at several
locations with alternate phone contact information.

Scheduling Outpatient Procedures at:

Orlando Health Orlando Regional Medical Center
The recommended first call is to 321.841.5274 to schedule the test
and then information may be sent by fax at 321.843.6039.

Peripheral Vascular Laboratory, Fourth Floor
Orlando Health Heart Institute
1222 S. Orange Ave., Orlando, FL 32806

Scheduling is done via Central Scheduling by phone or online.
You can reach the Peripheral Vascular Lab at Orlando Regional Medical Center
by calling 321.841.8590

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Orlando Health Physician’s Guide to TCD

ULTRASOUND CPT DIAGNOSIS CHECK ICD-10
PROCEDURE CODE (this partial list of commonly authorized FOR CODE
93880 diagnoses is a general guideline, and is not
Color Duplex Scanning intended to instruct in specific coding) DIAGNOSIS G 45.9
of the Extracranial 93882 G 45.3
Arteries Complete 93886 Transient Ischemic Attack (TIA) I 63.9
Bilateral Study Amaurosis Fugax I 65.29
Cerebral Infarction, unspecified (Stroke) G 5.0
(Carotid Doppler) Carotid Stenosis R 09.89
Vertebrobasilar Insufficiency(TIA) Z 13.6
(Noninvasive Study of the Carotid Bruit Z 98.89
Extracranial Arteries) Pre-op Major Vascular Procedure
Follow-up Carotid Endarterectomy
Color Duplex Scanning
of the Extracranial Syncope and Collapse R 55
Arteries Limited or Vertebrobasilar Insufficiency (TIA) G 45.0
Unilateral Subclavian Steal Syndrome G 45.8

i.e., Vertebrobasilar System Sickle Cell Disease D 57.1
Cerebral Infarction (CVA) unspecified I 63.9
Transcranial Doppler Transient Ischemic Attack (TIA) G 45.9
Imaging (TCDI) Carotid Stenosis or Occlusion I 65.29
MCA Stenosis or Occlusion I 66.09
(Transcranial Doppler study Basilar Artery Stenosis or Occlusion I 65.1
of the intracranial arteries, Precerebral Arterial Stenosis I 65.3
complete study) Arteriovenous Malformation Q 28.2
Subarachnoid Hemorrhage I 60.7
Positional VBI (Bow Hunter’s Syndrome) I 65.09

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Orlando Health Physician’s Guide to TCD

ULTRASOUND CPT DIAGNOSIS CHECK ICD-10
PROCEDURE CODE (this partial list of commonly authorized FOR CODE
diagnoses is a general guideline, and is not
Transcranial Doppler 93882 intended to instruct in specific coding) DIAGNOSIS
Imaging Limited Study
Vertebrobasilar Insufficiency G 45.0
i.e., Vertebrobasilar Basilar Artery Orthostatic Testing

Transcranial Doppler 93890 Carotid Stenosis I 65.29
Cerebrovascular 93886
Reserve 93880 Transient Ischemic Attack (TIA) G 45.9
93893
(add TCDI to all studies) MCA Stenosis or Occlussion I 66.09
93893
(add Carotid Doppler if Cerebral Infarction unspecified cause I 63.9
not done in last 12 mo.) Cerebral Infarction due to Embolism I 63.40

Transcranial Doppler Cerebral Infarction, other I 63.8
Protocol for Detection Cerebral Infarction due to Embolism I 63.40
of PFO Cerebral Infarction unspecified cause I 63.9

(Embolism Detection with
IV Microbubble Injection)

Transcranial Doppler
Protocol for Detection
of Cerebral Emboli

(Embolism Detection without
IV Microbubble Injection)

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MCI 5971-127099 11/2017 © 2017 Orlando Health, Inc.