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274
Table 14.2 (continued)
NCSE Non-invasive estimation of ICP
Perioperative cardiovascular and
aortic counterpulsation balloon
Cerebral venous thrombosis (CVT) Non-invasive estimation of ICP
Sepsis Changes in the cerebral perfusion pressure (CPP) as a
BDD brain death diagnosis, NCSE non-convulsive epileptic status, VV venous-venous/VA veno-
arterial, ARDS acute respiratory distress syndrome, CPP cerebral perfusion pressure, TCCS transcranial color-coded duplex sonography [43–51]
Cerebral autoregulation
Changes in the cerebral perfusion pressure (CPP) and
blood ow velocities
Detection of intra-extra-axial space-occupying lesions
Non-invasive estimation of ICP
Cerebral autoregulation
Changes in the cerebral perfusion pressure (CPP) and
blood ow velocities
Detection of Intra-extra-axial collection
Middle line shift (MLS)
Assessment of the cerebral deep venous system and dural
sinuses
Detection of intra-axial space-occupying lesion
risk factor to develop sepsis-associated encephalopathy
Non-invasive estimation of ICP
C. N. Rodríguez and D. Pugin
14.9 TCCS Protocol: Hemodynamic Parameters
With the use of transcranial color-coded duplex sonography (TCCS), we can obtain
information, in real time, about hemodynamic behavior and anatomical distribution
of the basal cerebral arteries:
1. Visualize: Access the anatomical landmarks to identify the different basal cerebral arteries to insonate
(B-Mode and color Doppler).
2. Flow Direction: Identify intracranial anatomical distribution of the basal cerebral arteries and ow direction of each one (Color-coded Doppler).
3. Flow Patterns: Identify the blood ow velocities and spectral Doppler waveform
of each insonated basal cerebral artery (PW Doppler) (Table14.3).
After identifying the vessel to insonate (Color Doppler), the pulsed wave Doppler
(PW Doppler) is placed to obtain the signal corresponding to the Doppler spectrum.
The hemodynamic parameters derived from the pulsed Doppler are as follows:
(a) Peak Systolic Velocity (PSV)
(b) End-Diastolic Velocity (EDV)
(c) Mean Flow Velocity (MFV)
(d) Pulsatility Index (PI)
(e) Resistance Index (RI)
14 Neurosonology in ICU: Transcranial Color-Coded Duplex Sonography (TCCS…
Table 14.3 Normal velocity values in the basal cerebral arteries [14, 16, 40, 53–60]
Artery
Middle cerebral artery (MCA) 90±16 45±10 62±12
Anterior cerebral artery (ACA) 78±18 35±6 50±15
Posterior cerebral artery (PCA) 53±11 26±7 37±10
Vertebral artery (VA) 40±12 20±5 29±15
Basilar artery (BA) 52±9 31±9 39±9
Table 14.4 Flow direction and waveform
Artery Flow direction Spectral waveform
Middle cerebral artery (M1– M2) Toward to the probe (red color) Low resistance
Anterior cerebral artery (A1) Away from the probe (blue color) Low resistance
Posterior cerebral artery (P1) Toward to the probe (red color) Low resistance
Posterior cerebral artery (P2) Away from the probe (blue color) Low resistance
Vertebral artery (VA) Away from the probe (blue color) Low resistance
Basilar artery (BA) Away from the probe (blue color) Low resistance
Ophthalmic artery (OA) Toward to the probe (red color) High resistance
PSV
(cm/s)
EDV
(cm/s)
MFV
(cm/s)
275
Table 14.5 Normal values
of the hemodynamic
indexes [54]
Artery Pulsatility index (PI)
Middle cerebral artery (MCA) 0.9±0.24
Anterior cerebral artery (ACA) 0.83±0.17
Posterior cerebral artery (PCA) 0.88±0.2
Vertebral artery (VA) 0.86±0.08
Basilar artery (BA) 0.86±0.09
As previously stated, if the blood ows toward the probe, it is color-coded red
and is positive. On the opposite, if the ow moves away from the probe, it is colorcoded blue and is negative (Table14.4). The shape of the ow curve gives an indication of the system’s resistance. If the diastolic velocities are low, the resistances are
high, while if the diastolic velocities are high, the resistances are low.
Using the velocities recorded for each vessel, a Pulsatility Index (PI) and
Resistance Index (RI) can be calculated (Table 14.5). Only the PI is used in the
TCCS analysis and is an indirect indication of the increased intracranial pressure. It
is worth noting that the ow rates of intracerebral arterial vessels decrease with the
age of the patient. On the contrary, pulsatility increases with the age of the
patient [61].
Remember that to obtain a more accurate measurement of the ow velocity, the
correction of the insonation angle with the positioning of the pulsed wave spectral
Doppler cursor as parallel as possible to the ow is mandatory (< 60°) [62].
276
C. N. Rodríguez and D. Pugin
14.10 TCCS Protocol: Limitations
The TCCS is not a perfect technique. Many aspects (technical and interpretative)
must be considered in order to obtain a reliable examination. Therefore, we should
keep in mind operator dependency and a 10–20% of patients having inadequate
transtemporal acoustic window.
14.10.1 Limitations
14.10.1.1 Acoustic Windows
The effectiveness of the transcranial color-coded duplex sonography (TCCS)
depends on the good penetrance of the ultrasound through the temporal bone and/or
through the suboccipital window:
Transtemporal Acoustic Window
There is a 10–30% of patients, in middle age, in which the study cannot be carried
out due to the lack of an adequate acoustic window. These values are decreasing as
the quality of the TCCS improves. Sometimes, the A2 segment of ACA is not possible insonated. Then, we should elect another acoustic window (Frontal bone
window).
Suboccipital Acoustic Window
Sometimes, the anatomical morphology of the vertebro-basilar arterial system is
tortuous where the insonation is difcult.
In the cervical syndromes, especially in the spinal cord injury, a neck exion to
access the suboccipital acoustic window to insonate the vertebro-basilar system is
not possible. Then, the submandibular acoustic window can be selected.
14 Neurosonology in ICU: Transcranial Color-Coded Duplex Sonography (TCCS…
277
14.10.1.2 Middle-Line Shift Measurement
This technique allows to measure the midline shift changes at bedside. It is important to keep in mind that a little tilt of the probe may alter the results [63–66]. This
ultrasound measure is difcult in case of subdural or epidural hematomas and in
clinical situations where the temporal window is temporarily (post-operative)
blocked or absent [48, 67].
On the other hand, the hydrocephalus should not alter the measurement [68, 72].
14.10.1.3 Limitations inSpecic Clinical Situations
Intra-/Extra-Axial Space-Occupying Lesions: Diagnosis andMonitoring
The TCCS is useful in the diagnosis and monitoring of intra- or extra-axial collections, which can be seen on the B-Mode. In case of subdural and epidural hematoma, a midline shift could be observed. This bedside exam may limit the use of
brain CT scan and their repetition. The suspicion of the location of the intra-axial
space-occupying lesions is important in determining the usefulness of brain ultrasound. Frontal and parietal collections may be the most difcult to detect.
14.11 Conclusion
The increase of ICU specialists with ultrasound abilities and availability of ultrasound machines in the ICU creates the best condition for a wider use of transcranial
color-coded duplex sonography (TCCS). As discussed in this chapter, this technique
provides many relevant clinical information at bedside that directly impact the therapeutic strategies in the acute neurological patients. TCCS allows intensivists to
provide an immediate evaluation next at patient’s bedside (24hours a day, 7days a
week) in both acute neurological injury (TBI, SAH, etc.) and non-neurological critical pathology (Sepsis, Acute liver failure, ARDS, RRT, etc.). Therefore, it is
expected and necessary that the use of the TCCS becomes a very valuable complement in the routine clinical investigations of the intensive care units.
278
Algorithm
C. N. Rodríguez and D. Pugin
ICPn
ESTIMATION
Transtemporal Window Transorbital Window
Mesencephalic
Plane
MEASUREMENT TRENDS
Pulsatility Index (PI)
MCA / ACA Oxygenation? Pupillary Diameter
PCA / BA CBFV -OA
Neurological
Monitoring
TRANSCRANIAL COLOR-CODED DUPLEX SONOGRAPHY (TCCS)
CEREBRAL HEMODYNAMIC BRAIN PARENCHYMA
FRONTAL BONE
WINDOW
1. Paramedian Zone Anterior Triangle
2. Supraorbital Zone Circle of Willis Mesencephalic Plane
3. Laterofrontal Zone Diencephalic Plane Mesencephalon
1. A1-ACA 2. ECA 3. A2-ACA 3. PICA 3th Ventricle
2. A2-ACA 3. ICA Ventricular Plane Thalamus
3. Circle of Willis M3-MCA Pineal Gland
SUBMANDIBULAR
WINDOW
Of Neck
1. CCA 2. M3-MCA 2. BA Diecenphalic Plane
CBFVs Spectral Doppler Waveform Sphenoid bone
Lindegaard Index Pulsatility Index Petrosal bone
Cerebral Autoregulation: Mx / PRx / Sx Anterior Coronal Plane
CONSIDER: Trendof the Measurements Frontal horns of LV
INTENSIVE CARE UNIT (ICU)
EMERGENCY DEPARTMENT (ED)
Clinical Status of the Patient
ABCD MI < 2.3
Level of Consciousness (GCS) TI < 2.0
Bilateral Pupillary Reactivity.
Hemodynamic Stability? ONSD
DIAGNOSIS
CRITICALLY ILL
PATIENT
TRANSTEMPORAL
WINDOW
Mesencephalic Plane Foramen Magnum
1. M2-MCA 1. V4-VA Perimesencephalic Cisterns
Upper PontinePlane Midline Shift (MLS)
Siphon-ICA Ventricular Plane
OA Frontal horns of LV
Lower Pontine Plane Upper Pontine Plane
C1-ICA Sphenoid bone
Anterior Coronal Plane Petrosal bone
C1-ICA Medial Cerebral Fossa
MEASUREMENTS Lower Pontine Plane
TRANSFORAMINAL
WINDOW
NEURO-ORBITAL
ULTRASOUND
SAFETY
ALARA
MEASUREMENT TRENDS
CBFV -CRA
Neurological
Compromise
ULTRASOUND
(B-Mode)
TRANSTEMPORAL
WINDOW
Cerebellum
ABCD Airway-breathing-circulation-disability, GCS Glasgow coma scale, FVs Peak systolic
velocity, FVm Mean velocity, MCA Middle cerebral artery, ACA Anterior Cerebral Artery, PCA
Posterior Cerebral Artery, BA Basilar Artery, VA Vertebral Artery, OA Ophthalmic artery, ONSD
optic nerve sheath diameter, CRA Central retinal artery, ICPn Non-invasive intracranial pressure,
CBFV Cerebral blood ow velocity, LV Lateral ventricle, PICA Postero- inferior cerebellar artery,
TI Thermal index, MI Mechanical index, Mx Mean ow index, Sx systolic ow index, PRx Pressure
reactivity index.
References
1. Arnolds BJ, Von Reutern GM. Transcranial Doppler sonography examination technique and
normal reference values. Ultrasound Med Biol. 1986;12:115–23.
2. Aaslid R, Markwalder TM, Nornes H.Noninvasive transcranial Doppler ultrasound recording
of fow velocity in basal cerebral arteries. J Neurosurg. 1982;57:769–72.
14 Neurosonology in ICU: Transcranial Color-Coded Duplex Sonography (TCCS…
3. Sloan MA, Alexandrov AV, Tegeler CH, Spence MP, Caplan LR, Feldmann E, etal. Assessment:
transcranial Doppler ultrasnongraphy: report of the therapeutics and technology assessment
Subcommittee of the American Academy of Neurology. Neurology. 2004;62:1468–81.
4. Bogdahn U, Becker G, Winkler J, Greiner K, Perez J, Meurers B.Transcranial colour-coded
sonography in adults. Stroke. 1990;21(12):1680–8.
5. Olatunji RB, et al. Role of Transcraneal colour-coded Duplex sonography in stroke
management- review article. West Afr J Ultrasound. 2015;16(1):33–42.
6. Williams, Warwick. Gray’s Anatomy, vol. I; 1986. p.755–762;813–827).Salvat.
7. Hartkamp MJ, etal. Circle of Willis collateral ow investigated by magnetic resonance angi-
ography. Stroke. 1999;30:2671–8.
8. Zhu G, Yuan Q, Yang J, Hock YJ.Experimental study of hemodynamics in the circle of Willis.
Biomed Eng. 2015;14(Suppl 1):S10.
9. Hoksbergen AWJ, Legemate DA, Ubbink DT, Jacobs MJHM.Collateral variants in circle of
Willis in atherosclerotic population assessed by means of transcranial color-coded duplex
sonography. Stroke. 2000;31:1656–60.
10. Kern R, Perren F, Kreisel S, et al. Multiplanar transcranial ultrasound imaging: stan-
dards, landmarks and correlation with magnetic resonance imaging. Ultrasound Med Biol.
2005;31:311–5.
11. Walter U.Transcranial sonography of the cerebral parenchyma:update on clinically relevant
applications. Pers Med. 2012;1:334–43.
12. Oliveira R, de Oliveira LM, Silva Paiva W, de Sá Malbouisson LM, Teixeira MJ, Bor-Seng-
Shu E.Comparison between brain computed tomography scan and transcranial sonography
to evaluate third ventricle width, Peri-mesencephalic cistern, and sylvian ssure in traumatic
brain-injured patients. Front Neurol. 2017;8:44.
13. Seidel G, Gerriets T, Kaps M, Missler U.Dislocation of the third ventricle due to space- occupying
stroke evaluated bytranscranialduplex sonography. J Neuroimaging. 1996;6(4):227–30.
14. Caricato A, Mignani V, Bocci MG, Pennisi MA, Sandroni C, Tersali A, et al. Usefulness of
transcranial echography in patients with decompressive craniectomy: a comparison with computed tomography scan. Crit Care Med. 2012;40(6):1745–52.
15. Zipper SG, Stolz E.Clinical application of transcranial color-coded dúplex sonography– a
review. Eur J Neurol. 2002;9:1–8.
16. AIUM practice guideline for the performance of a transcranial Doppler ultrasound examina-
tion for adults and children. American College of Radiology (ACR); Society for Pediatric
Radiology (SPR); Society of Radiologists in Ultrasound (SRU). J Ultrasound Med.
2012;31(9):1489–500.
17. Liu D, Kahn M.Measurement and relationship of subarachnoid pressure of the optic nerve to
intracranial pressures in fresh cadavers. Am J Ophthalmol. 1993;116(5):548–56.
18. Hayreh SS.Pathogenesis of oedema of the optic disc. Doc Ophthalmol. 1968;24(2):289–411.
19. Newman WD, Hollman AS, Dutton GN, Carachi R.Measurement of optic nerve sheath diam-
eter by ultrasound: a means of detecting acute raised intracranial pressure in hydrocephalus.
Br J Ophthalmol. 2002;86(10):1109–13.
20. Helmke K, Burdelski M, Hansen HC.Detection and monitoring of intracranial pressure dys-
regulation in liver failure by ultrasound. Transplantation. 2000;70(2):392–5.
21. Geeraerts T, Launey Y, Martin L, Pottecher J, Vigué B, Duranteau J, etal. Ultrasonography of
the optic nerve sheath may be useful for detecting raised intracranial pressure after severe brain
injury. Intensive Care Med. 2007;33(10):1704–11.
22. Bartels E. Transcranial color-coded duplex ultrasonography in routine cerebrovascular diag-
nostics. Pers Med. 2012;1:325–30.
23. Bartels E, Fuchs H-H, Flugel KA. Color Doppler imaging of basal cerebral arteries.
Examination technique and normal reference values. Angiology. 1995;10:844–77.
24. Geeraerts T, Thome W, Tanaka S, Leblanc PE, Duranteau J, Vigué B. An alternative ultra-
sonographic approach to assess basilar artery ow. Neurosurgery. 2011;68(2 Suppl
Operative):276–81.
25. Kim MJ, etal. Technical essentials of hepatic Doppler sonography. Curr Probl Diagn Radiol.
2009;38:53–60.
279
280
26. Giller CA.Is angle correction correct? J Neuroimaging. 1994;4:51–2.
27. Krejza J, Mariak Z, Babikian VL. Importance of angle correction in the measurement
of blood ow velocity with transcranial Doppler sonography. AJNR Am J Neuroradiol.
2001;22(9):1743–7.
28. Bartels E.Color– coded Duplex ultrasonography of the cerebral vessels: atlas and manual.
Stuttgart: Schattauer; 1999.
29. Nedelmann M, Stolz E, Gerriets T, etal. Consensus recommendations for transcranial color-
coded dúplex sonography for the assessment of intracranial arteries in clinical trials in acute
stroke. Stroke. 2009;40:3238–44.
30. Stolz E. Ultrasound examination techniques of extra – and intracranial veins. Pers Med.
2012;1:366–70.
31. Bartels E.The axial imaging plane-the main domain of the transcranial color-coded duplex
ultrasonography? Eur J Ultrasound. 2002;16:47–57.
32. Becker G, Lindner A, Bogdahn U.Imaging of the vertebro-basilar system by transcranial
colour-coded real-time sonography. J Ultrasound Med. 1993;12:395–401.
33. Stolz E, Nückel M, Mendes I, Gerriets T, Kaps M. Vertebrobasilar transcranial colour-
coded duplex ultrasonography: improvement with echo enhancement. Am J Neuroradiol.
2002;23:1051–4.
34. Becker G, Lindner A, Bogdahn U. Imaging of the vertebrobasilar system by transcranial
colour-coded real-time sonography. J Ultrasound Med. 1993;12:395–401.
35. Schöning M, Walter J.Evaluation of the Vertebrobasilar-posterior system by transcranial color
duplex sonography in adults. Stroke. 1992;23:1280–6.
36. Geeraerts T, Thome W, Tanaka S, Leblanc PE, Duranteau J, Vigué B. An alternative ultra-
sonographic approach to assess basilar artery ow. Neurosurgery. 2011;68(2 Suppl
Operative):276–81.
37. Alexandrov AV, Sloan MA, Wong LK, Douville C, Razumovsky AY, Koroshetz WJ, etal.
American Society of Neuroimaging Practice Guidelines Committee Practice standards for
transcranial Doppler ultrasound: part I—test performance. J Neuroimaging. 2007;17(1):11–8.
38. Csiba L, Baracchini C.Manual of neurosonology. Chapter 2A.Cambridge; 2016.
39. Christopher H.Optic nerve sheath diameter ultrasound and the diagnosis of increased intracra-
nial pressure. Crit Care Nurs Clin N Am. 2016;28:95–9.
40. Ertl M, Barinka F, Torka E, etal. Ocular color-coded sonography– a promising tool for neu-
rologists and intensive cara physicians. Ultraschall Med. 2014;35:422–31.
41. Bäuerle J.Nedelmann M.B-mode sonography of the optic nerve in neurological disorders with
altered intracranial pressure. Pers Med. 2012;1:404–7.
42. Abadal JM, Llompart-Pou JA, Homar J, Pérez-Bárcena J, Ibáñez J. Applications of tran-
scranial color-coded duplex sonography in monitoring neurocritical patients. Med Intensiva.
2007;31(9):510.
43. Kavi T, Esch M, Rinsky B, Rosengart A, Lahiri S. Transcranial Doppler changes in
patients treated with extracorporeal membrane oxygenation. J Stroke Cerebrovasc Dis.
2016;25(12):2882–5.
44. Pierrakos C, Antoine A, Velissaris D, Michaux I, Bulpa P, Evrard P, etal. Transcranial Doppler
assessment of cerebral per- fusion in critically ill septic patients: a pilot study. Ann Intensive
Care. 2013;3:28.
45. Joshi B, Ono M, Brown C, Brady K, Easley RB, Yenokyan G, etal. Predicting the limits of
cerebral autoregulation during car- diopulmonary bypass. Anesth Analg. 2012;114(3):503–10.
46. Rasulo FA, De Peri E, Lavinio A.Transcranial Doppler ultrasonography in intensive care. Eur
J Anaesthesiol. 2008;25(S42):167–73.
47. Rasulo FA, Bertuetti R, Robba C, Lusenti F, Cantoni A, Bernini M, etal. The accuracy of
transcranial Doppler in excluding intracranial hypertension following acute brain injury: a
multicenter prospective pilot study. Crit Care. 2017;21(1):44.
48. Moppett IK. Transcranial Doppler ultrasonography in anaesthesia and intensive care. Br J
Anaesth. 2004;93(5):710–24.
C. N. Rodríguez and D. Pugin
14 Neurosonology in ICU: Transcranial Color-Coded Duplex Sonography (TCCS…
49. Motuel J, Biette I, Srairi M, Mrozek S, Kurrek MM, Chaynes P, et al. Assessment of brain
midline shift using sonography in neurosurgical ICU patients. Crit Care. 2014;18(6):676.
50. Naqvi J, Yap KH, Ahmad G, Ghosh J.Transcranial Doppler ultra- sound: a review of the physi-
cal principles and major applications in critical care. Int J Vasc Med. 2013;2013:629378.
51. Saqqur M, Zygun D, Demchuk A.Role of transcranial Doppler in neurocritical care. Crit Care
Med. 2007;35(5):S216–23.
52. Blanco P, Abdo‐Cuza A.Transcranial Doppler ultrasound in the ICU: it is not all sunshine and
rainbows. Crit Ultrasound J. 2018;10:2.
53. Schöning M, Buchholz R, Walter J.Comparative study of transcranial color duplex sonogra-
phy and transcranial Doppler sonography in adults. J Neurosurg. 1993;78:776–84.
54. Rigamonti A, Ackery A, Baker AJ.Transcranial Doppler monitoring in subarachnoid hemor-
rhage: a critical tool in critical care. Can J Anaesth. 2008;55:112–23.
55. Schöning M, Walter J.Evaluation of the vertebrobasilar-posterior system by transcranial color
duplex sonography in adults. Stroke. 1992;23:1280–6.
56. D’Andrea A. Transcranial Doppler ultrasonography: from methodology to major clinical
applications. World J Cardiol. 2016;8(7):383–400.
57. Schöning M, Niemann G, Hartig B. Transcranial color duplex sonography of basal cerebral
arteries: reference data of ow velocities from childhood to adulthood. Neuropediatrics.
1996;27:249–55.
58. Blanco P, Blaivas M. Applications of transcranial color-coded sonography in the emergency
department. J Ultrasound Med. 2017;36:1251–66.
59. Aaslid R, Markwalder TM, Nornes H.Noninvasive transcranial Doppler ultrasound recording
of ow velocity in basal cerebral arteries. Neurosurgery. 1982;57:769–74.
60. Babikian VL, Wechsler LR, Toole JF. Transcranial Doppler ultrasonography. 2nd ed.
Butterworth Heinemannn; 1999.
61. Grolimund P, Seiler RW.Age dependence of the ow velocity in the basal cerebral arteries:a
transcranial Doppler ultrasound study. Ultrasound Med Biol. 1988;14:191–8.
62. Bartels E, Flügel KA. Quantitative measurements of blood ow velocity in basal cerebral
arteries with transcranial color Doppler imaging. J Neuroimag. 1994;4:77–81.
63. Wu TY, Sharma G, Strbian D, etal. Natural history of perihematomal edema and impact on
outcome after intracerebral hemorrhage. Stroke. 2017;48(4):873–9.
64. Kiphuth IC, Huttner HB, Struffert T, etal. Sonographic moni- toring of ventricle enlargement
in posthemorrhagic hydrocephalus. Neurology. 2011;76:858–62.
65. Llompart Pou JA, Abadal Centellas JM, Palmer Sans M, etal. Moni- toring midline shift by
transcranial color-coded sonography in traumatic brain injury. A comparison with cranial computerized tomography. Intensive Care Med. 2004;30:1672–5.
66. Tang SC, Huang SJ, Jeng JS, etal. Third ventricule evidence shift due to spontaneous supra-
tentorial intracerebral hemorrhage evaluated by transcranial color-coded sonography. J
Ultrasound Med. 2006;25:203–9.
67. White H, Venkatesh B. Applications of transcranial Doppler in the ICU: a review. Intensive
Care Med. 2006;32(7):981–94.
68. Lau VI, Arnteld RT. Point-of-care transcranial Doppler by intensivists. Crit Ultrasound
J. 2017;9:21.
69. Sentenac P, etal. The frontal bone window for transcranial Doppler ultrasonography in criti-
cally ill patients: validation of a new approach in the ICU.Neurocrit Care. 2020;33(1):115–23.
70. Yoshimura S. Frontal bone window improves the ability of transcranial color-coded sonog-
raphy to visualize the anterior cerebral artery of Asian patients with stroke. AJNR Am J
Neuroradiol. 2009;30:1268–9.
71. Stolz E, Kaps M, Kern A, Dorndorf W.Frontal bone windows for transcranial color-coded
duplex sonography. Stroke. 1999;30:814–20.
72. Lau VI, Jaidka A, Wiskar K, Packer N, Tang JE, Koenig S, etal. Better with ultrasound: tran-
scranial Doppler. Chest. 2020;157(1):142–50.
281
Chapter 15
Fc
()
Transcranial Color-Coded Duplex
Sonography (TCCS): Importance ofAngle
Correction
PiergiorgioLochner, AntonioSiniscalchi, andAndreaNaldi
Key Points
1. Angle correction can be performed by TCCS, allowing a more real measurement
of cerebral vessels’ ow velocity compared to not angle-corrected ones.
2. TCCS angle-corrected velocity is proportional but not equal to the true velocity.
3. Angle correction should be performed when the Doppler sample volume identi-
es a sufcient straight vessel segment (at least 15mm in length) in order to
ensure a correct assessment.
4. Angle correction should be performed when the angle between the ultrasonic
beam and the vessel is small, in other way be likely to produce signicant errors.
5. The angle-corrected velocity with TCCS is signicantly higher as compared to
the uncorrected velocity of the same system or to conventional TCD.
15.1 Introduction
Based on the Doppler equation (Eq.15.1)
∆Fv
=
P. Lochner (*)
Department of Neurology, Saarland University Medical Center, Homburg, Germany
e-mail: piergiorgio.lochner@uks.eu
A. Siniscalchi
Department of Neurology and Stroke Unit, Annunziata Hospital, Cosenza, Italy
A. Naldi
Department of Neuroscience Rita Levi Montalcini, University of Turin, Turin, Italy
C. N. Rodríguez et al. (eds.), Neurosonology in Critical Care,
https://doi.org/10.1007/978-3-030-81419-9_15
2• •cos /
α
(15.1)
283© Springer Nature Switzerland AG 2022
284
(incident frequency)
r
P. Lochner et al.
where ΔF is the Doppler shift, F is the frequency of incident wave, and c is the
propagation speed. Flow velocity (v) of a target vessel depends on the cosine of the
angle (α) between the ultrasonic beam and blood ow (Fig.15.1).
Thus, in ideal circumstances, if the ultrasound (US) beam is parallel to ow
direction (angle α=0), the cos α=1 and ow velocity will correspond to reality. On
contrary, when the US beam is perpendicular to ow direction (angle α=90°), the
cos α =0, resulting in a weak receiving signal and false ow velocity. Therefore,
one of the most important limiting factors for the estimation of correct blood ow
velocity is represented by the angle of insonation. The impact of the angle insonation
on ow velocities is relatively low in a range of 0–30°, and it is still considered
acceptable until 60°. On contrary, angle >60° generates large variation in the cosine
used for the correction, resulting in signicant errors of measurements [1] (Fig.15.2).
Moreover, we should keep in mind that the arteries of circle of Willis can have a
different angle of insonation of ultrasound and angle of vessel. In 10%, the insonation
angle of anterior cerebral artery (ACA) is more than 40° and in 33% the angle of
posterior cerebral artery (PCA) is between 31° and 40° [2].
Two techniques are currently available for the assessment of intracranial vessel
ow velocity: transcranial Doppler (TCD) (Fig.15.3) and transcranial color-coded
duplex sonography (TCCS).
In conventional TCD, the identication of cerebral arteries is based on the position of transducer, ow direction, and insonation depth. Introduced since the 80s,
this technique was also dened as “blind sonography,” because it does not allow a
direct visualization of brain vessels. Even if the insonation angle is uncertain, it is
assumed to be 0 degree, or anyway small enough (range 0–30°) to not determine
signicant errors of measurements [3, 4]. On this basis, normative values of intracranial arteries blood velocity have been proposed and widely used (Table15.1).
On the other hand, the more recent TCCS allows the combination of B-mode and
color Doppler imaging, permitting the real-time visualization of parenchymal
Fig. 15.1 The alpha angle
(α) of the Doppler equation
is determined by the
intersection between the
incident frequency emitted
by the ultrasound
transducer and the
direction of blood ow
Blood flow
Receiving frequency
Ultrasonic beam
Transduce
α