B Mode Ultrasonic Imaging – An Effective Screening Tool for Carotid Artery Disease

Portable ultrasound scanners have the ability to take the diagnosis to the patient either in the community or to patients on the ward.

Colour Doppler Systems: Picus, MyLab20

Detailed here is an example of the use of a  Small and portable scanner Falco for screening for carotid artery disease.

Dr Simon Ward Vascular Laboratory, Royal Sussex Hospital, Brighton

(Paper presented to the Society for Vascular Technology of UK and Ireland Wednesday 18^th November 1998)

Available systems: Falco, Aquila(Greyscale)

This Study was an attempt to establish the effectiveness of a portable high resolution B-mode imaging system as a screening tool where access to a colour duplex system may be limited or restricted.

Routine carotid artery scanning of 35 patients using an Acuson 128XP system was followed by a scan by a second technologist using the Falco Very easy and affordable system or Aquila portable B-mode imaging system with a 7MHz linear Probe. The B-mode scan was performed blind to the Acuson scan and with the technologist unaware of the patient’s symptoms or the reason for referral. The technologist performing the B-mode scan made a sketch of what was seen and answered the question:- "Is there disease in the distal common or internal carotid arteries which appears to be causing a diameter stenosis in excess of 25%?".

Seventy carotid trees were examined and were available for comparison. 23 (34%) of the carotid trees examined demonstrated stenosis of greater than 25% on duplex scanning. The B-mode scan was able to detect significant disease as defined with a sensitivity of 96% and specificity of 87%, more importantly for a screening tool a negative predictive value of 98% was achieved. In the one instance in which the B-mode scan failed to correctly identify disease of greater then 25%, the actual stenosis was considered to be less than 50%.

B-mode imaging alone has the ability to accurately demonstrate the absence or presence of the carotid artery disease. In situation where access to a duplex system is problematic, particularly where transport of patients between sites is necessary, a portable high resolutions B-mode imaging system could provide a viable method of determining which patients require a further investigation.