Hyperechogenicity of medial gastrocnemial veins during ultrasound scanning of the calf in sitting patients: a normal variant.

Abstract

The goal of this study was to evaluate the prevalence and significance of the high echogenicity of blood frequently encountered in medial gastrocnemial veins (MGVs) during venous ultrasound scanning of the calf in sitting patients. Using a commercially available multi-frequency linear probe an experienced radiologist prospectively analysed a series of 97 legs from 59 patients referred to the ultrasound department for various clinical reasons; echogenic ambulatory outpatients being free of calf venous thrombosis were only considered. Hyperechogenicity of blood in MGVs was visible in 67 of 97 calfs (69%); it was discrete or moderate in 23 calfs (23.7%) and intense in 44 calfs (45,36%); 97% of these 67 calfs contained large MGVs whose diameter was at least twice that of the other muscular veins. The "washing out" manoeuvre applied to these veins by direct compression with the probe was effective to prove their normal permeability; after releasing of compression, hyperechogenicity was spontaneously restored in a mean time of 47.45+/-16.85 s. Because of a very low flow and a diameter commonly larger than other muscular veins, MGVs probably frequently reach a sufficiently low shear rate to promote aggregation causing echogenicity of blood when patients are examined in a sitting position. For this reason, hyperechogenicity of MGVs, instead of being a manifestation of local stasis, represent a reversible physiological normal variant. Nevertheless, the careful dynamic compression of these veins during ultrasound scanning is necessary to distinguish this normal variant from deep venous thrombosis.