Transcranial Doppler (TCD) Imaging

Transcranial Doppler (TCD) Imaging This Job Aid reviews the location, insonation depth, color, and Pulse Wave Doppler (PW) for the main segments of the intracranial arteries from the temporal and occipital windows. The circle of Willis is the intracranial arterial collateral system. Ultrasound imaging of the circle of Willis necessitates a handheld phased array transducer at a low frequency optimized for TCD. Du- plex imaging combines two-dimensional (2D-mode) and Color Doppler with PW Doppler spectral tracing to document the intracranial arterial system's blood flow direction and mean velocity. Duplex imaging is performed at specific acoustic windows on the skull over naturally occurring foramina or thin bone areas. 1 Temporal Window Occipital Window Diagram 1 – Temporal and occipital windows. Suboccipital and submandibular approaches are patient- dependent. Acoustic Windows – The temporal window accesses the intracranial arteries through thinner sections of the temporal bone. Diagram 1 is an example of the transducer approach from the temporal and occipital win- dows. The temporal window and access points vary from anterior to the ear, slightly above the ear, posterior to the ear, or closer to the face. The occipital acoustic window is roughly central, at the base of the skull between the occipital bone near the attachment of the ligamentum nuchae. Unrestricted | Published by Siemens Healthcare GmbH © Siemens Healthcare GmbH, 2021 SIEMENS Master Template Effective Date: 10 Aug 2021 | HILS 2224 Job Aid Effective Date: 14 FEB 2022 | HOOD05162003236375 Healthineers Job Aid | Transcranial Doppler (TCD) Imaging Effective Date: 24 FEB 2022 | HOOD05162003236375 Axial Orientation Sagittal Orientation Diagram 2 – These cross sectional diagrams across the intracranial arterial segements show the co-location of the transducer at the temporal and occipital windows. The teal-colored transducers are on the temporal window, and the orange-colored transducers are at the occipital window. The axial plane shown in this diagram aligns the orientation marker toward the face. The sagittal plane aligns the orientation marker toward the top of the head. Orientation – Ultrasound imaging of the intracranial arterial segments begins with either axial or sagittal trans- ducer orientation. Typically, the axial plane aligns the orientation marker toward the patient's face, and the sagittal cross-section aligns the orientation marker toward the apex of the head, as shown in Diagram 2. A modification of the axial plane aligns the orientation marker toward the back of the head. Transducer alignment strategies used for TCD Imaging have evolved from the indirect methods used in Non-Imaging TCD. As a result, TCD Imaging orientation approaches may differ between laboratories. However, consistent alignment methods help improve the diagnostic accuracy of comparison or follow-up TCD imaging examinations. Follow laboratory-specific guidelines and procedures regarding transducer orientation. SIEMENS Healthineers Page 2 of 16 Job Aid | Transcranial Doppler (TCD) Imaging Effective Date: 24 FEB 2022 | HOOD05162003236375 - A1 M2 M1 Temporal - C7 - P2 P1 BA 1Occipital VA Diagram 3 – Side view of the most common acoustic windows and the main segments of the anterior and posterior intracranial arteries. Intracranial Arterial Segments – Arterial segments shown in Diagram 3 include the terminal bifurcation of the Internal Carotid Artery (ICA) at segment C7. The terminal ICA branches at the A1 segment of the Anterior Cerebral Artery (ACA), Posterior Communicating Artery (PcomA), and the Middle Cerebral Artery (MCA) M1 segment. The M2 segment of the MCA is just proximal to the point where the MCA branches. Sim- ilarly, the A2 segment of the ACA is distal to the AcomA. The transtemporal window can also elu- cidate the PcomA, as shown in Diagram 3. The P1 segment of the PCA occurs at the distal bifur- cation of the Basal Artery (BA) and the P2 segment of the PCA is proximal to the P2a and P2b bi- furcation. Image the main segments of the posterior intracranial arteries from the occipital window. The posterior arteries include the right and left vertebral arteries (VA), the Basal Artery (BA), and the P1 and P2 segments of the PCA. 2 SIEMENS Healthineers Page 3 of 16 Job Aid | Transcranial Doppler (TCD) Imaging Effective Date: 24 FEB 2022 | HOOD05162003236375 M1 P2 C1 A2 A1 P VA PcomA BA A2 A1 P1 VA AcomA C1 IM1 P2 Diagram 4 – Teal markers identify the anterior and posterior communicating arteries (AcomA and PcomA), collaterals of a complete circle of Willis. Collateral Circulation – In a complete circle of Willis, both the Anterior Communicating Artery (AcomA) and the Posterior Communicating Artery (PcomA) provide collateral flow between the anterior and posterior arterial systems. Diagram 4 highlights an example of the AcomA and PcomA. Anatomic variations and anomalies of the communicating arteries exist. 2 SIEMENS Healthineers Page 4 of 16 Job Aid | Transcranial Doppler (TCD) Imaging Effective Date: 24 FEB 2022 | HOOD05162003236375 Intracranial Artery and Blood Flow Direction – Color Doppler is a valuable tool to visualize the intracranial blood flow direction. However, the blood flow direction of the intracranial arteries is relative to the transducer location on the pa- tient's head. The transducer's location to the arterial segments is described as either ipsilateral or contralateral. The ipsilateral artery is on the same side as the transducer and the contralateral artery is on the opposite side. Therefore, in instances where one acoustic window reveals the con- tralateral cMCA, cACA, and cPCA, keep in mind that the relative transducer alignment and trans- ducer location help distinguish blood flow direction. For example, the ipsilateral MCA blood flow is toward the transducer and the blood flow direction is away from the transducer on the cMCA as described in Diagram 5. Sequoia 38 5V1 IIB: 1.32 TIC:3.21 MCA TIS:1.32 MI:0.93 2D Mid PCA 6dB/DR60 C Pen 1dB 38 PRF 1812 ACA C C MCA C PCA 15cm Diagram 5 – In this example, the co-location of the transducer appears next to the ultrasound image. The transducer is at the left transtemporal window with an axial projection. The color Doppler region of interest (ROI) is over the circle of Willis, demonstrating ipsilateral (left side) MCA, ACA, and PCA and contralateral blood flow from the contralateral (right side) cMCA, cACA, and cPCA. SIEMENS Healthineers Page 5 of 16 Job Aid | Transcranial Doppler (TCD) Imaging Effective Date: 24 FEB 2022 | HOOD05162003236375 The sagittal transtemporal view aims to isolate the anterior arterial segments of the circle of Willis where the terminal ICA bifurcates into the MCA and ACA. When clinically indicated, this view may help identify the C7 or terminal segment of the ICA. Align the transducer directly over the ipsilateral MCA as shown in Diagram 5 and carefully rotate to a sagittal projection. Diagram 6 shows an example of this transtemporal sagittal view where the MCA and ACA bifurcate at the terminal ICA bilaterally (ipsilateral and contralaterally). 75 IB:1.2 3.29 TIS:1.27 MI:1.14 2D Mid 4dB/DR60 MCA OdB 12 Is ACA Terminal ICA PRF 3521 c ACA c Terminal ICA C MCA 14 cm Diagram 6 – The transducer is on the left temporal window with a sagittal orientation, rotated 90-degrees clockwise from Diagram 5. The color Doppler ROI is over the anterior segments of the circle of Willis, revealing the terminal ICA at the bifurcation of the ACA and MCA bilaterally (yellow ar- rows). SIEMENS Healthineers Page 6 of 16 Job Aid | Transcranial Doppler (TCD) Imaging Effective Date: 24 FEB 2022 | HOOD05162003236375 Anatomically, the A1 segments of the ACA are aligned closely, and it is not easy to distinguish the color Doppler flow of the ipsilateral ACA from the contralateral ACA within the same transtem- poral window. The transducer position is slightly anterior and away from the ipsilateral MCA in Diagram 7, optimizing the ipsilateral ACA by slowly angling the transducer slightly anteriorly. As a result, blood flow from the ipsilateral ACA is toward the transducer. The contralateral anterior communicating artery (cACA) reveals blood flow away from the transducer. 38 5V1 TIB:1.28 TIC:3.18 TIS:1.28 MI:0.97 2D Mid 6dB/DR60 C ACA A1 Terminal ICA Pen 1dB 38 PRF 1812 AcomA-> CACA A1 12cm Diagram 7 – Again, the co-location of the transducer is next to the ultrasound image. The transducer is at the left transtemporal window with an axial projection and angled slightly anterior from the MCA (toward the face). On the Duplex image, the ipsilateral and contralateral A1 segments are circled in teal and shown proximal to the AcomA. SIEMENS Healthineers Page 7 of 16 Job Aid | Transcranial Doppler (TCD) Imaging Effective Date: 24 FEB 2022 | HOOD05162003236375 In Diagram 8, the transducer is at the occipital window with a sagittal projection. The transducer is tilted anteriorly, with the cable end of the transducer nearly aligned to the nape of the neck. The ultrasound image orientation is conventional, meaning the orientation indicator on the im- age screen (circled in white) is on the left side of the image screen, and represents the patient's right side. The sagittal view can yield the intracranial segments of the right and left VA (the VA bifurcation) and optimize the proximal and distal segments of the BA. Blood flows from each vertebral into the BA and is normally away from the transducer from this location. Rotate the transducer 90-degrees clockwise for axial views (orientation marker to the patient's right side) at the occipital window to interrogate the right or left VA's proximal and distal segments as clinically indicated. 46 5V1 TIB:1.34 TIC.3.19 MI. 1.02 2D Mid 1dB/DR60 C Rt VA Pen 1dB Lt VA PRF 2155 BA Proximal BA Distal 11 cm Diagram 8 – The occipital transducer position is in the sagittal projection, and Color Doppler demonstrates the BA and both intracranial segments of the VA. SIEMENS Healthineers Page 8 of 16 Job Aid | Transcranial Doppler (TCD) Imaging Effective Date: 24 FEB 2022 | HOOD05162003236375 TCD Imaging of the Main Intracranial Arterial Segments with Color and Spectral Doppler – Non-imaging or blind TCD has established the PW Doppler depth ranges, standard blood flow di- rections, and insonation windows to document intracranial arterial segments. TCD Imaging incor- porates the traditional PW Doppler depth range and the blood flow direction coupled with visual clues to help verify the intracranial arterial location. Note that intracranial arterial segment depth and anatomy vary. Therefore, on serial exams, maintain the same PW Doppler sample depth and image settings for the arteries examined. 2 Non-imaging or blind TCD instrumentation documents the mean velocity without angle correc- tion and is the predominant source for most PW Doppler reference values published. Likewise, TCD Imaging documents PW Doppler waveforms without angle correction, assuming a cosign of zero. Notwithstanding, a lack of angle correction for TCD Imaging may underestimate the mean velocity. Follow laboratory-specific TCD Imaging guidelines regarding PW Doppler documentation and angle correction methods. TCD Imaging illustrated chart – The following illustrated chart describes ten examples of the acoustic window, normal color, PW Doppler mean velocity, and PW Doppler depth range used to resolve the intracranial arterial seg- ments. The red arrow indicates the general blood flow direction either toward the transducer or away. The average TCD mean velocities are age, sex-dependent, and vary within patient populations. Therefore, the mean velocity ranges represented in this document do not represent all healthy populations or clinical circumstances. 3, 4, 7 SIEMENS Healthineers Page 9 of 16 Job Aid | Transcranial Doppler (TCD) Imaging Effective Date: 24 FEB 2022 | HOOD05162003236375 MCA M1 - Mean Velocity 55 cm/s ± 12 cm/s Depth 45 to 65 mm 1, 5, 6 PS=87.95 cm/s ED=48.19 cm/s RI=0.45 PI=0.62 Mean TCD=61.44 cm/s 38, 12cm 55mm 50 00 -0.50 - m/s .................................................................................................................................... MCA M2 -Mean Velocity 55 cm/s ± 12 cm/s Depth 45 to 65 mm 1, 5, 6 PS=69.46 cm/s ED=32.69 cm/s RI=0.53 PI=0.82 Mean TCD=44.95 cm/s 12 cm 45mm - 1.50 - 1.00 -0.50 m/s I ......... The MCA M2 segment is just proximal to the bifurcation, and the mean velocity drops slightly from the MCA M1 segment. Also, the MCA M2 segment is closer to the transducer but distal to the MCA M1 segment. Therefore, specific depths of the MCA M2 may segment vary. Verifying MCA branching with TCD Imaging provides necessary landmarks to identify the M2 segment of the MCA. SIEMENS Healthineers Page 10 of 16 Job Aid | Transcranial Doppler (TCD) Imaging Effective Date: 24 FEB 2022 | HOOD05162003236375 Terminal ICA @ C7 - Mean Velocity 55 cm/s ± 12 cm/s Depth 60 to 70 mm 1, 5, 6 sequote PS=57.25 cm/s ED=29.70 cm/s RI=0.48 PI=0.70 Mean TCD=38.88 cm/s 12cm 66mm - 100 50 - cm/s -50 ............................................................................................................................... The transducer orientation remains axial in this example from the terminal ICA at C7. Sagittal orientation is an option as described above and as clinically indicated. SIEMENS Healthineers Page 11 of 16 Job Aid | Transcranial Doppler (TCD) Imaging Effective Date: 24 FEB 2022 | HOOD05162003236375 ACA A1 - Mean Velocity 40 cm/s ± 11 cm/s Depth Away 60-75 mm 1, 5, 6 PS=44.19 cm/s ED=19.58 cm/s RI=0.56 PI=0.91 Mean TCD=27.78 cm/s 38 12cm 61mm -100 -50 cm/s 50 Slightly tilt the transducer toward the face from the terminal ICA and follow the ACA toward the face. The A1 segment of the ACA occurs at the location where blood flow begins to flow away from the transducer. The ACA A2 segment is distal from the A1 segment. ACA A2 - Mean Velocity 40 cm/s ± 11 cm/s Depth 70 to 90 mm 1, 5, 6 PS=48.37 cm/s ED=25.80 cm/s RI=0.47 PI=0.75 MCA Mean TCD=33.32 cm/s ACA PCA AZ C PCA 38, 12cm 78mm 20 cm/s NYC -20 40 -60 80 100 ...................................................................................................................................... SIEMENS Healthineers Page 12 of 16 Job Aid | Transcranial Doppler (TCD) Imaging Effective Date: 24 FEB 2022 | HOOD05162003236375 PCA P1 - Mean Velocity 39 cm/s ± 10 cm/s Depth 60 to 70 mm 1, 5, 6 PS=41.02 cm/s ED=17.53 cm/s RI=0.57 PI=0.82 MCA Mean TCD=25.36 cm/s ACA PCA CPCA 15cm 61mm -100 -80 -60 -40 -20 cm/s 1 ........... ....... . L.20 PCA P2 - Mean Velocity 40 cm/s ± 10 cm/s Depth 60 to 70 mm 1, 5, 6 PS=50.66 cm/s ED 23.20 cm/s RI=0.54 PI=0.78 Mean TCD=32.35 cm/s 12cm 60mm 40 20 cm/s 20 www -40 - 60 80 The P2 segment of the PCA is just proximal to the PCA bifurcation. Take advantage of TCD Imag- ing to locate the bifurcation of the ipsilateral PCA. However, take care not to mistake the contra- lateral (cPCA) for the ipsilateral PCA P2 segment because the Doppler direction for both are away from the transducer. SIEMENS Healthineers Page 13 of 16 Job Aid | Transcranial Doppler (TCD) Imaging Effective Date: 24 FEB 2022 | HOOD05162003236375 Intracranial Right VA - Mean Velocity 38 cm/s ± 10 cm/s Depth 60 to 90 mm 1, 5, 6 PS=53.37 cm/s ED=26.68 cm/s RI=0.50 PI=0.71 Mean TCD=35.58 cm/s 11cm 56mm -20 cm/s 20 -- 40 60 80 100 Intracranial Left VA - Mean Velocity 38 cm/s ± 10 cm/s Depth 60 to 90 mm 1, 5, 6 PS-33.48 cm/s ED=16.56 cm/s RI=0.51 PI=0.66 Mean TCD=22.20 cm/s 42 11cm 66mm 20 cm/s 20 -40 -60 -80 I.100 SIEMENS Healthineers Page 14 of 16 Job Aid | Transcranial Doppler (TCD) Imaging Effective Date: 24 FEB 2022 | HOOD05162003236375 Basal Artery - Mean Velocity 41 cm/s ± 10 cm/s Depth 90 to 100 mm 1, 5, 6 PS=46.50 cm/s ED=22.02 cm/s RI=0:53 PI=0.77 5V1 Mean TCD=30.18 cm/s TIC 2 26 42 PRF 198 11cm 98mm 120B/OR60 PRF 6250 cm/s 20 -- 40 60 80 ....................... References Used: 1. Alexandrov, A.V., Sloan, M.A., Wong, L.K., Douville, C., Razumovsky, A.Y., Koroshetz, W.J., Kaps, M., Tegler, C. H., (2017) Practice standards for transcranial Doppler ultrasound: part I-test performance. J Neuroimaging. 17(1),11-8 2. Purkayastha, S. and F. Sorond.,(2012),Transcranial Doppler ultrasound: technique and application. Seminars in Neurology. 32(4), 411-420 3. Szydlik, P., Mariak, Z., Krejza, J., Swiercz, M., Keller, A.,(2000),Transcranial color Doppler estimation of blood flow parameters in respective basal cerebral arteries in healthy subjects. Neurol Neurochir Pol. 34(3), 523-36 4. Extracranial Cerebrovascular Duplex Ultrasound, in Professional Performance Guidelines. 2019, Society for Vascular Ultrasound. p. 1-7 5. Baumgartner, R.W., (2006) Handbook of Neurovascular Ultrasound, in Frontiers of Neurology and Neuroscience, R.W. Baumgartner, Editor. Karger. p. 285 6. Reehal, N., Cummings, S., Mullen, M. T., Baker, W. B., Kung, D., Tackett, W., Favilla, C. G., (2021) Differentiating Dynamic Cerebral Autoregulation Across Vascular Territories. Front Neurology. 12, p. 1-7 7. Bartels, E., Flugel, K. A., (1994) Quantitative measurements of blood flow velocity in basal cerebral arteries with transcranial duplex color-flow imaging. A comparative study with conventional transcranial Doppler sonography. Neuroimaging. (4)2, 77-81 SIEMENS Healthineers Page 15 of 16 Job Aid | Transcranial Doppler (TCD) Imaging Effective Date: 24 FEB 2022 | HOOD05162003236375 Please note that the learning material is for training purposes only. For the proper use of the software or hardware, please always use the Operator Manual or Instructions for Use (here- inafter collectively "Operator Manual") issued by Siemens Healthineers. This material is to be used as training material only and shall by no means substitute the Operator Manual. Any material used in this training will not be updated on a regular basis and does not necessarily reflect the latest version of the software and hardware available at the time of the training. 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