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9 Transcranial Doppler (TCD/TCCS) and Cerebral Blood Flow Velocities: Parameters…
Table 9.10 Mean ow velocity (MFV) and pulsatility index (PI) values by sex [27]
Artery MFV (cm/s), SD PI, SD
Men Female Men Female
MCA(M1) 48.7±15.5 49.6±14.4 0.8±0.1 0.7±0.1
ACA(A1) 40.4±12.9 39.7±12.6 0.8±0.2 0.8±0.2
eICA 31.5±5 36.4±6.7 0.9±0.2 0.8±0.1
PCA(P1) 34±12.3 34.9±12.2 0.8±0.1 0.8±0.1
PCA(P2) 33.8±9.9 35±8.2 0.8±0.2 0.9±0.3
Basilar 32.5±8.9 39.2±10 0.8±0.2 0.8±0.2
V4 25.6±6 26.3±6.9 0.7±0.2 0.7±0.2
ACA anterior cerebral artery, ICA internal carotid artery, MCA middle cerebral artery, PCA poste-
rior cerebral artery, SD standard deviation, MFV mean ow velocity
Table 9.11 Mean ow velocity (MFV) and pulsatility index (PI) by age [27]
Artery MFV (cm/s), SD PI, SD
<40years >40years <40years >40years
MCA(M1) 52.7±14.4 44.1±13.8 0.8±0.1 0.7±0.1
ACA(A1) 42.4±13 36.1±11 0.8±0.2 0.8±0.1
eICA 35.3±6.3 33.5±6.8 0.8±0.1 0.8±0.2
PCA(P1) 35.7±13.7 32.9±9.5 0.8±0.1 0.8±0.1
PCA(P2) 35.7±9.1 32.9±8.4 0.8±0.2 0.9±0.3
Basilar 37.4±11.3 35.7±8.1 0.8±0.1 0.8±0.2
V4 25.7±6.2 26.5±7.1 0.7±0.2 0.7±0.2
ACA anterior cerebral artery, ICA internal carotid artery, MCA middle cerebral artery, PCA poste-
rior cerebral artery, SD standard deviation, MFV mean ow velocity
173
between the two groups. In the posterior circulation, the inter-hemispheric differences were fewer and not statistically signicant.
The hemodynamic parameters recorded using TCD differ from those published
in other series with subjects with no history of disease. The lower CBFV values
recorded appear to be inuenced by altitude and haematocrit [28]. Hence, the consideration of these results could have an impact on the assessment and therapeutic
decisions in patients with acute neurological injury.
9.9 TCD Hemodynamic Parameters: Recommendations
forLocal Assessment ofNormal Values
Reference values for a local population should be constructed by insonating healthy
subjects at rest in a calm and comfortable setting. The operator should be an expert
in the TCD technique, and it is preferable to limit the number of operators in order
to avoid potential bias of inter-observer variability, although if the operators have
similar level of expertise the variability should be non-signicant [4].
174
J. H. Mejía Mantilla et al.
The sample should include subjects of both sexes in similar proportions and a
distribution of ages similar to the potential patient’s ages for the laboratory, for adult
laboratory ages from 18 to 90years old. In order to obtain statistical power for each
subgroup, there must be at least 10 subjects for each decade for each gender
(A. Garcia, personal communication). Considering 10 to 15% of non-insonable
window, it would be better to include 12 cases per decade [24].
The criteria for denition of normal or the criteria to include non-normal individuals should be explicit, considered as part of the reference population of interest
for the authors.
9.10 Conclusion
Transcranial Doppler ultrasound is an established technology useful to evaluate
cerebral circulation at the bedside. Its portability, absence of irradiation and noninvasiveness make this approach especially useful in critically ill patients; furthermore, TCD/TCCS can be repeated as many times as needed with no harm to the
patient and at low cost, making TCD the most versatile way to evaluate cerebral
circulation at the ICU.
The interpretation of TCD/TCCS is operator dependent and can be inuenced by
the reference values considered normal for a given population; it is important for
each TCD/TCCS laboratory to develop its own table of normal values for the local
population.
References
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of ow velocity in basal cerebral arteries. J Neurosurg. 1982;57(6):769–74.
2. Bishop CC, Powell S, Rutt D, Browse NL.Transcranial Doppler measurement of middle cere-
bral artery blood ow velocity: a validation study. Stroke. 1986;17(5):913–5.
3. Lindegaard KF, Nornes H, Bakke SJ, Sorteberg W, Nakstad P. Cerebral vasospasm after
subarachnoid haemorrhage investigated by means of transcranial Doppler ultrasound. Acta
Neurochir Suppl (Wien). 1988;42:81–4.
4. Maeda H, Etani H, Handa N, Tagaya M, Oku N, Kim BH, etal. A validation study on the
reproducibility of transcranial Doppler velocimetry. Ultrasound Med Biol. 1990;16(1):9–14.
5. Puppo Vallini BC.Doppler transcraneano en el paciente neurocrítico. Paciente crit (Uruguay).
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6. Baumgartner I, Behrendt P, Rohner P, Baumgartner RW.A validation study on the intraob-
server and interobserver reproducibility of renal artery duplex ultrasound. Ultrasound Med
Biol. 1999;25(2):225–31.
7. Arnolds BJ, von Reutern GM.Transcranial Doppler sonography. Examination technique and
normal reference values. Ultrasound Med Biol. 1986;12(2):115–23.
8. Hennerici M, Rautenberg W, Sitzer G, Schwartz A.Transcranial Doppler ultrasound for the
assessment of intracranial arterial ow velocity--part 1. Examination technique and normal
values. Surg Neurol. 1987;27(5):439–48.
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9. Sorteberg W, Langmoen IA, Lindegaard KF, Nornes H. Side-to-side differences and day-
to- day variations of transcranial Doppler parameters in normal subjects. J Ultrasound Med.
1990;9(7):403–9.
10. Vriens EM, Kraaier V, Musbach M, Wieneke GH, van Huffelen AC. Transcranial pulsed
Doppler measurements of blood velocity in the middle cerebral artery: reference values at rest
and during hyperventilation in healthy volunteers in relation to age and sex. Ultrasound Med
Biol. 1989;15(1):1–8.
11. Schmidt EA, Piechnik SK, Smielewski P, Raabe A, Matta BF, Czosnyka M.Symmetry of
cerebral hemodynamic indices derived from bilateral transcranial Doppler. J Neuroimaging.
2003;13(3):248–54.
12. Droste DW, Ludemann P, Anders F, Kemeny V, Thomas M, Krauss JK, etal. Middle cerebral
artery blood ow velocity, end-tidal pCO2 and blood pressure in patients with obstructive
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Neurol Res. 1999;21(8):737–41.
13. Macchi C, Catini C.The measurement of the calibers and blood-ow velocities of the arteries
of the circle of Willis: a statistical investigation of 120 living subjects using transcranial colorDoppler ultrasonography. Ital J Anat Embryol. 1994;99(1):9–16.
14. Krejza J, Mariak Z, Walecki J, Szydlik P, Lewko J, Ustymowicz A.Transcranial color Doppler
sonography of basal cerebral arteries in 182 healthy subjects: age and sex variability and normal reference values for blood ow parameters. AJR Am J Roentgenol. 1999;172(1):213–8.
15. Tegeler CH, Crutcheld K, Katsnelson M, Kim J, Tang R, Passmore Grifn L, etal. Transcranial
Doppler velocities in a large, healthy population. J Neuroimaging. 2013;23(3):466–72.
16. Grolimund P, Seiler RW.Age dependence of the ow velocity in the basal cerebral arteries--a
transcranial Doppler ultrasound study. Ultrasound Med Biol. 1988;14(3):191–8.
17. Yang D, Cabral D, Gaspard EN, Lipton RB, Rundek T, Derby CA.Cerebral hemodynamics in
the elderly: a transcranial Doppler study in the Einstein aging study Cohort. J Ultrasound Med.
2016;35(9):1907–14.
18. Brouwers PJ, Vriens EM, Musbach M, Wieneke GH, van Huffelen AC.Transcranial pulsed
Doppler measurements of blood ow velocity in the middle cerebral artery: reference values at
rest and during hyperventilation in healthy children and adolescents in relation to age and sex.
Ultrasound Med Biol. 1990;16(1):1–8.
19. Ringelstein EB, Kahlscheuer B, Niggemeyer E, Otis SM. Transcranial Doppler sonography:
anatomical landmarks and normal velocity values. Ultrasound Med Biol. 1990;16(8):745–61.
20. Barbosa MF, Abdala N, Carrete H Jr, Nogueira RG, Nalli DR, Fonseca JR, etal. Reference
values for measures of blood ow velocities and impedance indexes in healthy individuals
through conventional transcranial Doppler. Arq Neuropsiquiatr. 2006;64(3B):829–38.
21. Demirkaya S, Uluc K, Bek S, Vural O.Normal blood ow velocities of basal cerebral arteries
decrease with advancing age: a transcranial Doppler sonography study. Tohoku J Exp Med.
2008;214(2):145–9.
22. Donnelly J, Budohoski KP, Smielewski P, Czosnyka M.Regulation of the cerebral circulation:
bedside assessment and clinical implications. Crit Care. 2016;20(1):129.
23. Farhoudi M, Kermani S, Sadeghi-Bazargani H.Relatively higher norms of blood ow velocity
of major intracranial arteries in North-West Iran. BMC Res Notes. 2010;3:174.
24. Franco M, Ariza-Araújo Y, Mejía-Mantilla JH.Estimación de valores hemodinámicos medi-
ante el uso del doppler transcraneal en un grupo de voluntarios habitantes de Cali (Colombia),
una ciudad a 995m sobre el nivel del mar. Imagen Diagnóstica. 2015;6(2):49–56.
25. Moller K, Paulson OB, Hornbein TF, Colier WN, Paulson AS, Roach RC, etal. Unchanged
cerebral blood ow and oxidative metabolism after acclimatization to high altitude. J Cereb
Blood Flow Metab. 2002;22:118–26.
26. Brass LM, Pavlakis SG, DeVivo D, Piomelli S, Mohr JP.Transcranial Doppler measurements
of the middle cerebral artery effect of hematocrit. Stroke. 1988;19:1466–9.
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27. Scherle Matamoros CE, Rivero RD.Transcranial Doppler ultrasound measurements of cere-
bral hemodynamic parameters in healthy volunteers at 2850 meters altitude. Radiology.
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28. Isikay CT, Uzuner N, Gücüyener D, Ozdemir G. The effects of hematocrit and age on
transcranial Doppler measurements in patients with recent ischemic stroke. Neurol India.
2005;53:51–4.
J. H. Mejía Mantilla et al.
Chapter 10
Transcranial Doppler (TCD/TCCS)
Approaches: Acoustic Windows
JorgeCarrizosa
Key Points
1. Proper insonation technique is essential to achieve better visualization of struc-
tures and trustable ow velocities in transcranial Doppler evaluation.
2. A standardized routine of insonation should be applied to decrease intra- and
interobserver variability.
3. Transcranial color-coded duplex sonography is an easy, reproducible, and non-
invasive method to evaluate critical care patients at the bedside.
4. To know the acoustic windows and their related target structures will allow a
complete evaluation of the brain hemodynamics in most cases.
5. The sonographer/physician must know considerations about age, gender, ethnic-
ity, and other conditions related to hard-to-insonate windows.
10.1 Introduction
Neurological evaluation is not easy in neurocritical care patients to understand brain
dynamics and to anticipate complications as deep sedation is common. Multimodal
neuromonitoring has emerged as a strategy to evaluate the central nervous system in
critical care patients. Hemodynamic instability, risk of complications during transfer to the imaging department, and need for frequent evaluation of brain hemodynamics represent usual conditions of the neurocritical ill patient. Non-invasive
monitoring strategies are essential and necessary to avoid complications during
transfer to other wards and to enable frequent evaluation. Transcranial Doppler
J. Carrizosa (*)
Intensive Care Medicine, Hospital Universitario Fundación Santa Fé, Bogotá, Colombia
Neurointensive Care section - AMCI, Bogotá, Colombia
e-mail: magnusdronjak@hotmail.com
C. N. Rodríguez et al. (eds.), Neurosonology in Critical Care,
https://doi.org/10.1007/978-3-030-81419-9_10
177© Springer Nature Switzerland AG 2022
178
J. Ca rr izosa
sonography was described rst by Aaslid in 1982 as a technique for examination of
intracranial cerebral arteries [1].
In the last years, with the advent of focused ultrasound protocols [2], routine
evaluation of the critical care patient is becoming a mandatory skill, including
assessment of the central nervous system. Nowadays, there are two methods to
assess brain with ultrasound: transcranial Doppler limited to evaluation of brain
ow velocities and transcranial color-coded duplex sonography, which permits
assessment of central nervous system in brightness mode (B-mode). To master skills
performing an ultrasound to obtain the best images possible is necessary to avoid
misdiagnosis.
The purpose of this chapter is to guide the technique of the insonation of the
brain through different acoustic windows, structured assessment, the target of evaluation, and evaluation routine on both sides—additionally, a description of some
recommendations to optimize structure visualization and optimize image views.
10.2 TCD/TCCS: Acoustic Windows
Inner skull structures are not easy to evaluate randomly with ultrasound as the bone
is a strong reector. To know anatomy to identify thinner areas of the skull is mandatory in routine evaluation during ultrasound evaluation. In order to achieve visualization of relevant anatomical structures, a 2.0–3.5MHz phased array transducer
is necessary (Fig. 10.1).
Additionally, transcranial Doppler ultrasound preset in ultrasound machines with
similar software facilitates quick identication of different structures (Fig. 10.1b).
Fig. 10.1 Ultrasound
probes indicated for
transcranial Doppler
ultrasound in comparison.
TCD transcranial Doppler;
TCCD transcranial
color-coded sonography
10 Transcranial Doppler (TCD/TCCS) Approaches: Acoustic Windows
a
b
179
Fig. 10.2 (a) Sonographer/physician position behind the patient, ensuring comfort to perform
complete transcranial Doppler evaluation. (Author: Jorge Carrizosa). (b) Physician showing dexterity in transcranial Doppler examination with both hands. (Author: Jorge Carrizosa)
Comfort is fundamental for the sonographer/physician, who should be located
behind the patient when it is possible (Fig.10.2a). However, head access in that way
could be difcult in critical care patients due to other monitoring devices, wires, and
extracorporeal support machines. Some modications to the usual position should
be done in many cases. Acquiring skills to insonate the brain with both hands is
essential to achieve adequate insonation (Fig.10.2b).
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J. Ca rr izosa
10.2.1 Transtemporal Acoustic Window (Table10.1)
10.2.1.1 Technique
Place the 2.0–3.5MHz phased array transducer in B-mode image at the temporal
bone cephalad to the zygomatic arch and anterior to the ear with probe indicator
alienated with the plane of the eye of the patient -axial- (Fig.10.3). In this position,
the very rst target of visualization is the midbrain, visualized as a hypoechoic
buttery-shaped surrounded by the hyperechoic cisterns (Fig.10.4a, b). The initial
depth of insonation of 15 centimeters is recommended, recognizing the contralateral side of the skull as a hyperechoic image [3]. Then, slight tilt movements in
cephalocaudal direction scanning downward and upward identify different planes
with particular anatomical structures, as shown in Fig.10.5.
After scanning of transtemporal planes in B-mode image, color-coded Doppler
is activated with midbrain visualization in the center of the image in order to identify the circle of Willis. The probability of recognizing the circle of Willis as midbrain is displayed is high, even in non-expert practitioners [4].
Table 10.1 Target of visualization: transtemporal window
Targets of visualization
B-mode: midbrain, third ventricle, thalami, basal ganglia, frontal horns, pineal gland, and insula
Color Doppler and pulsed wave Doppler modes: circle of Willis (middle cerebral artery[MCA],
anterior cerebral artery[ACA], posterior cerebral artery[PCA], top of the basilar cerebral
artery), terminal segment of the internal carotid artery[ICA])
Fig. 10.3 Transtemporal
window showing position
of the transducer:
1-vertical axis anterior to
the ear; 2-horizontal axis
cephalad to the zygomatic
arch; 3-probe indicator
(green dot), alienated with
the plane of the eye of the
patient. Yellow window
indicates the area for
exploration of the anterior
temporal window. (Author:
Jorge Carrizosa)
10 Transcranial Doppler (TCD/TCCS) Approaches: Acoustic Windows
181
a
Fig. 10.4 Transtemporal window examination. (a) B-mode image highlighting in the zoomed yellow square the hypoechoic area of the midbrain. (b) Color-coded image of the same plane of
insonation showing midbrain and surrounding vascular structures of the circle of Willis. (Author:
Jorge Carrizosa)
a
b
b
Fig. 10.5 (a) Complete circle of Willis is shown with gain increased for educational clarity. (b)
Same picture in image A with demarcation of the different arteries in the circle of Willis with different colors. Black boxes are indicating every artery name. Triangle: superior cerebellar artery;
pentagon: top of the basilar artery. (Author: Jorge Carrizosa)
The direction of blood ow should be useful to a better understanding of brain
vascular anatomy in the color-coded Doppler display as vessels with ow toward
the transducer are coded red while those with ow away from the transducer are
coded blue. In this insonation plane, the ipsilateral middle cerebral artery (MCA)
(red) is M1–M2 segments, M3 (blue) segment; the ipsilateral anterior cerebral
artery (blue) is A1–A2 segments; and the ipsilateral posterior cerebral artery (red) is
P1 and P2 (blue) segments as displayed.
In the complete circle of Willis patients, anterior communicating artery and posterior communicating artery could be identied. Contralateral A1 and M1 segments
are also common in patients with an adequate transtemporal window (Fig.10.5a, b).
Once identied the circle of Willis in color-coded Doppler display, the practitioner
can proceed to pulsed-wave Doppler mode to appraise cerebral arterial and venous
spectral waves and measure velocities of blood ow at every point of interest.
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J. Ca rr izosa
Color-coded Doppler scanning in the same planes as B-mode image explained
before is also recommended. By slightly tilting the transducer in a caudal direction,
the terminal segment of the internal carotid artery can be noticed. Coronal plane
insonation could also be done by rotating the transducer by 90° at the P1 segment
(posterior coronal plane), allowing the visualization of the top of the basilar
artery [4].
10.2.2 Transforaminal Acoustic Window (Table10.2)
10.2.2.1 Technique
Place the 2.0–3.5MHz phased array transducer in B-mode image suboccipital at the
midline and pointed toward the nasion (Fig.10.6), identifying the bone border of the
foramen magnum and the clivus. Activate the color Doppler mode box and identify
both intracranial segments of vertebral arteries lateral to the foramen magnum.
Sigmoid sinus is usually visualized at this point. Then, tilt the transducer upward
following the vertebral arteries to nd their junction with the basilar artery at 75–80
millimeters approximately (Fig.10.7). The path of the basilar artery can be tracked
Table 10.2 Target of visualization: transforaminal Window
Targets of visualization
B-mode: foramen magnum
Color Doppler and pulsed wave Doppler modes: vertebral arteries, basilar artery, posterior
inferior cerebral arteries, sigmoid sinus
a
Fig. 10.6 (a) Insonation of transforaminal window showing correct angle of insonation with ultrasound beam toward the nasion (green dot). (b) Transforaminal window insonation in a critical care
patient. Note how a folded pillow helps to place the transducer in proper position. (Author: Jorge
Carrizosa)
b