Transcript Document
Introduction to Transcranial Doppler / TCD TCD and TCDI Principles Objectives • • • • • List clinical applications for TCD Identify the architecture of the Circle of Willis Recognize data used for TCD interpretation Describe advantages of TCD imaging Identify TCD features of the MicroMaxxTM system Cervical Vascular Anatomy Cerebrovascular Anatomy Transcranial Doppler • Provides functional information about physiological flow states • Identifies anatomical location • Demonstrates the extent and degree of severity of various abnormalities American Academy of Neurology Position Statement (1989) • TCD is of established value in assessing – – – – – Servere stenosis of major basal arteries (>65%) Collateral circulation Vasoconstrictions AVM’s Brain Death TCD Utilization • Cardiology – Pre-operative extracranial carotid evaluation – Assessment of Intracranial collateral pathways – Emboli Monitoring TCD Utilization • Neuroradiologists – – – – – – Trauma Tumor/space occupying lesion Aneurysm detection AVM’s Vasospasm Brain death TCD Utilization • Vascular and Neurology Specialists – Assessment of intracranial collateral pathways in patients with extracranial carotid disease – Evaluation of response to revascularization – Evaluation of intracranial vascular lesion – Documentation of Subclavian Steal Syndrome – Assessment of Vertebrobasilar system – Monitor and manage Sickle Cell disease Understanding Non-Imaging TCD TCD-Non-Imaging TCD • Trace or map out the vessels only using the Doppler spectrum • Record bilateral depths and means equally • Compare vessels side to side, close to exact sample depths • Non-imaging is successful in 90% of the patient population TCDI-Imaging TCD • Advantages – Increased confidence in identification of vessels and pathology – Identification of anatomical variations – Quick identifications of abnormal flow patterns – Possibility of angle corrections • Disadvantages – Obtainable in 75-80% of the patient population A complete Circle of Willis is present in 50% of the population A perfect configuration of the Circle of Willis is present in only 18% of the population Vessel Identification Non-Imaging • • • • • • • Depth of Sample Volume Direction of flow Angle of transducer Traceability of vessel Spatial relationships between vessels Response to CCA oscillations or compressions All of these are utilized to “prove” what vessel you are insonnating Vessel Identification Imaging • • • • • • Depth of Sample Volume Direction of flow Angle of transducer Traceability of vessel Spatial relationships between vessels No need to “prove” vessels, because you can easily see where the vessel lie within the image Normal Values (Mean Velocities) VesselsMean MCA(M1) ACA PCA Siphon OA Basilar Vertebral t-ICA D-ICA Depth 62+12 50+11 39+10 47+14 21+ 5 41+10 38+10 39+ 9 37+ 9 Flow Direction 30-67mm Towards 60-80mm Away 55-75mm Towards 60-80mm Towards/Away 40-60mm Towards >80 Away 60-85mm Away 50-60mm Away 35-70mm Away Investigator Variability Author Aaslid DeWitt Gromlimund Harders Ringlestein Zanette Sorteberg Russo MCA 62+12 62+12 57+15 65+17 55+12 56+12 73+11 65+13 ACA 51+12 52+12 49+15 50+13 50+11 50+10 58+9 48+20 PCA 44+11 42+10 37+10 40+9 39+10 43+7 43+10 35+18 Physiologic Factors • • • • • • • • Age Gender Hematocrit Fever Hypoglycemia Carbon Dioxide Heart Rate/Cardiac Output/Blood Pressure Brain Activity Prior to TCD Exam • What is going on with the patients cerebrovascular and cardiovascular system? • Scan the patients carotid or have a recent carotid exam report • Find out if patient has had a recent echocardiogram Prior to TCD Exam Normal Exam Prior to TCD Exam Abnormal Exam Prior to TCD Exam Previous Patient Report Prior to TCD Exam Cardiac Mass TCD: Normal Direction of Flow TCD Imaging Orientation TCD & TCDI Protocol and Interpretation Access Windows Transorbital Window Transtemporal Window Submandibular Window Transoccipital/ Suboccipital Window TCDI-Transtemporal Window Boney Landmarks Lesser wing of the Sphenoid Bone Petrous Ridge Lesser Wing Of the Sphenoid Bone Petrous Ridge Foramen Lacerum Foramen Lacerum Foramen Lacerum TCDI-Transtemporal Window Segments recorded in a complete exam • MCA ( Prox, Mid, Distal ) • ACA • PCA ( P1 and P2 ) • tICA (Terminal ICA) TCDI- Submandibular Window Segments recorded in a complete exam • Distal ICA ( Internal Carotid Artery ) TCDI- Suboccipital Window Segments recorded in a complete exam • Vertebral arteries ( Right and Left ) • Basilar artery ( Prox, Mid, Distal ) TCDI- Transorbital Window Segments recorded in a complete exam • Ophthalmic Artery • Carotid Siphon Ophthalmic Artery TCDI-Transtemporal Window Low PRF Optimized PRF Be aware of your PRF settings when interrogating the Circle of Willis arterial segments High PRF TCDI-Transtemporal Window Low PRF Optimized PRF Be aware of your PRF settings when interrogating the Circle of Willis arterial segments High PRF TCDI-Transtemporal Window Low PRF Optimized PRF Be aware of your PRF settings when interrogating the Circle of Willis arterial segments High PRF TCD Interpretation Patients Clinical Presentation • • • • • • • • SAH Head injury Tumor AVM Aneurysm Extracranial vascular disease Subclavian steal syndrome Brain death TCD and TCDI Interpretation Criteria • MCA carries 80% of flow to the cerebral hemispheres • MCA mean velocities >ACA>PCA>Basilar >Vertebral • Normal mean velocities should be <90 cm/s • Mean velocities with mild vessel narrowing are >120c m/s TCD and TCDI Interpretation Criteria • Elevations in Mean Velocities may be due to: – Vasospasm – associated with trauma, SAH (subarrachnoid hemorrhage), aneurysm • Generalized increase in velocities • Changes over time – Stenosis – focal increase in velocity with PST – Collateral flow – associated with change in direction – Hyperdynamic flow – associated with head injury/AVM • Increased velocities in all vessels TCD and TCDI Interpretation Criteria • Pulsatility Index – Measures the peripheral resistance in the vascular bed – Absolute values alone are not very accurate, but changes in PI over time is an indicator of the severity of dilation – Normal = .9 – 1 MicroMaxx Patient / Exam Type TM • TCD – High output power • Orbital – Low output power MicroMaxx Doppler Quantification TM • Auto Trace results – Fast and reproducible – Displays • • • • • • • • TAP ( TCD mean ) Peak Velocity End Velocity Pulsatility Index Resistive Index Systolic/Diastolic Ratio Doppler Gate Size Sample Volume Depth – Manual Trace also available MicroMaxx TCD Report Pages TM Summary • MicroMaxxTM offers the clinician a complete cardiovascular imaging system • Small, portable system easily taken to patients’ bedside • TCD and Orbital exam types • Comprehensive report package • High-end application on an affordable system