<prompt> An asymptomatic old patient presents with bruit in the carotid artery. Which of the following is the investigation of choice?Doppler ultrasonographyInternal carotid angiographyAortic arch angiographySpiral CT angiography  <response>: Bruit over carotid artery suggests carotid artery stenosis.Duplex scanning B-mode scan and doppler ultrasonic velocimetry is the method of choice for assessing the degree of carotid stenosis. 