Validation of transcranial Doppler with CT angiography in cerebral ischaemia: a preliminary pilot study in Singapore.
BACKGROUND
Transcranial Doppler (TCD) is an established tool for the non-invasive assessment of cerebral blood flow. Since TCD results vary with the skills and experience of the sonographer, it requires validation against contrast angiography. We evaluated the diagnostic accuracy of TCD against computed tomography angiography (CTA) and the feasibility of the latter as an additional screening tool in our acute ischaemic stroke patients.


METHODS
Our stroke unit manages about 700 patients annually. Acute stroke patients undergo TCD for vascular assessment of major arteries of the circle of Willis. Randomly selected acute stroke patients with significant stenosis on TCD underwent high-resolution cranial CTA with multidetector helical scanner. CTA was performed within 24 hours of TCD and images were interpreted by a neuroradiologist blinded to TCD findings. An independent neurosonologist reevaluated TCD if CTA findings were contradictory. Additional information by either modality was also noted.


RESULTS
Fifteen patients (12 men, mean age 61 +/- 15years) with cerebral ischaemia and moderate (>50%) stenosis in > or =1 large intracranial arterial segment on routine TCD were evaluated by CTA. Compared with 21 segments of significant stenosis on CTA, TCD showed 16 true-positive, 3 false-positive and 5 false-negative results (sensitivity: 76.2%, positive predictive value: 84.2%). In 3 cases, TCD showed findings complementary to CTA (real-time embolisation, collateral flow patterns, evidence of distal M2 branch occlusion).


CONCLUSIONS
TCD in our neurovascular laboratory shows a satisfactory agreement with cranial CTA in evaluating patients with cerebral ischaemia. TCD can provide additional real-time dynamic findings complementary to information provided by CTA.
Rathakrishnan
Rahul
R
Division of Neurology, Department of Medicine, National University Hospital, Singapore.
Berne
Yeh I
YI
Quek
Keng K
KK
Hong
Chiew S
CS
Ong
Benjamin Kc
BK
Chan
Bernard Pl
BP
Sharma
Vijay K
VK
D000368:Aged; D002545:Brain Ischemia / Q000175:diagnosis*; D002533:Cerebral Angiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D012846:Singapore; D014057:Tomography, X-Ray Computed; D017585:Ultrasonography, Doppler, Transcranial