(Ultrasound Review) A prospective trial performed by researchers at Währinger Gürte General Hospital in Vienna, investigated the use of Levovist in diagnosing suspected calf vein thrombosis. Levovist, an ultrasound contrast agent comprising microbubbles, increases backscatter and hence improves Doppler sensitivity.
Patients at risk for deep vein thrombosis (DVT) commonly present leg swelling. The oedema increases sound attenuation and, along with patient obesity, provides significant difficulty when using ultrasound for diagnosing leg DVT particularly in the calf. These findings were presented in the April issue of Ultrasound in Medicine and Biology.
Twenty patients suspected of having calf vein thrombosis were studied first with color Doppler ultrasound with and without Levovist, then ascending venography. The latter examination diagnosed calf thrombosis in seven patients and was used as the "gold standard."
Ultrasound was performed using a 5 MHz linear array transducer with color Doppler parameters optimized for low velocity sensitivity. Levovist was infused via the cubital vein in a concentration of 400 ml/mL at a rate of 2 mL/min. The rate of indeterminate scans for noncontrast ultrasound was 55%.
That percentage was reduced to 20% when Levovist was utilized. Specificity for calf vein thrombus detection went from 25% to 67% for scans performed using Levovist but sensitivity was reduced from 100% to 86%, which was still considered acceptable.
"Quality of assessment was classified as improved in those patients where more anatomical details of the three calf vein segments could be clearly visualized after intravenous infusion of Levovist," the authors stated.
The authors concluded that using the contrast agent Levovist improved the quality of Doppler examination of the calf vein particularly in technically difficult patients with swelling and/or obesity.
"Contrast enhancement decreases the rate of indeterminate examinations and increases without compromising sensitivity notably," the authors stated.
However, when Levovist was used, there remained four indeterminate cases. The authors suggested that duplex ultrasound isn’t the best modality for diagnosing calf vein thrombus. Instead, they recommended contrast phlebography or MR venography as the preferred imaging techniques.
"Ultrasound with Levovist in the diagnosis of suspected calf vein thrombosis"R.A. Bucek et al
Clinic for Internal Medicine II-Department of Angiology, General Hospital, Währinger Gürte; 18-20, A-1090, Vienna, Austria
Ultrasound in Medicine and Biology 2001(April); 27:455–460
By Ultrasound Review
August 6, 2001
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