Transcranial Doppler ultrasonography: From methodology to major clinical applications

Table 1 Factors influencing cerebral blood flow velocit

Factor change in CBFV
Age	Increase up 6-10 yr then decrease
Sex	Women > men
Pregnancy	Decrement in the III Trimester
Hematocrit	Increase with decreasing Hct
PCO2	Increase with increasing PCO2
Main	Arterial pressure increase with increasing MAP

CBFV: Cerebral blood flow velocity; MAP: Mean arterial pressure.

Table 2 Mean cerebral blood flow velocity (cm/s) related to age

Artery	Age 20-40 yr	Age 40-60 yr	Age > 60 yr
Anterior cerebral artery	56-60	53-61	44-51
Middle cerebral artery	74-81	72-73	58-59
Posterior cerebral artery P1	48-57	41-56	37-47
Posterior cerebral artery P2	43-51	40-57	37-47
Vertebral artery	37-51	29-50	30-37
Basilar artery	39-58	27-56	29-47

Table 3 Intracranial arteries: Severity of vasospasm

	MFV (cm/s)	LR	LR modified
MCA or ICA vasospasm
Mild (< 25%)	120-149	3-6
Moderate (25%-50%)	150-199	3-6
Severe (> 50%)	> 200	> 6
BA vasospasm
Possible vasospasm	70-85		2-2.49
Moderate (25%-50%)	> 85		2.5-2.99
Severe (> 50%)	> 85		> 3

MCA: Middle cerebral artery; ICA: Internal carotid artery; LR: Lindegaard ratio; BA: Basilar artery; MFV: Mean flow velocity. MCA: Middle cerebral artery; ICA: Internal carotid artery; LR: Lindegaard ratio; BA: Basilar artery; MFV: Mean flow velocity.

Table 4 Grade of transient right to left shunting based on microembolic signals grading score

Grade transient shunt	MES
No shunt	0
Low grade shunt	1-10
Moderate grade shunt	11-25
High grade shunt	> 25 (shower) or uncountable (curtain effect)

MES: Microembolic signals.

Table 5 Diagnostic role of transcranial Doppler and its accuracy

Ref.	No. of patients	Sensitivity (%)	Specificity (%)	Accuracy (%)	Cut-off for RLS
Serena et al[48], 1998	55	100	100	100	≥ 1 MES1
Lange et al[49], 2010	26	31	100	65.5	≥ 9 MES
González-Alujas et al[52], 2011	93	97	98	97.5	≥ 1 MES
Mojadidi et al[51], 2014	1968	97	93	95	Meta-analysis2

¹In this study c-TCD performs better than c-TEE;

²This study is a large meta-analysis comprising 27 studies. TCD: Transcranial Doppler; c-TCD: Contrast enhanced TCD; TEE: Transesophageal echocardiography; RLS: Right-to-left shunting; MES: Microembolic signals.