Liquid crystal thermography as a screening test for deep-vein thrombosis.

The accuracy of liquid crystal colour thermography and clinical examination was compared with that of X-ray venography in 80 patients clinically suspected of having unilateral, lower-limb, deep-vein thrombosis. The clinical examination was not helpful in diagnosis. Of the 35 patients with confirmed deep-vein thrombosis, 34 had a positive thermogram, giving a sensitivity of 97%. 17 false-positive thermograms gave a specificity of 62%. The predictive value of a negative thermogram was 96.5%. Liquid crystal colour thermography is a quick, inexpensive, non-invasive investigation that might be useful as a screening test in patients suspected of having unilateral, lower-limb, deep-vein thrombosis. A diagnostic scheme starting with liquid crystal thermography and followed by 99mTc venoscanning might obviate the need for X-ray venography in almost 80% of patients with suspected deep-vein thrombosis.