[Quality control of Doppler diagnoses in vascular neurology]

The use of ultrasonography in the study of extracranial pathologies is becoming widespread among the different neurology services in our community. Its main limitation is that it is a technique that depends on the explorer.

The purpose of this study is to determine the reliability of our Neurosonology laboratory by validating its results.

We conducted a retrospective study by selecting the first 100 consecutive patients (with ischemic stroke) who had been examined in the year 2001 in the Neurosonology laboratory in our hospital. These subjects had to fulfil the requirement of having been submitted to both a Doppler study (carotid and transcranial) and a vascular neuroimaging study using magnetic resonance angiography (MRA) or panarteriography of the supra-aortic trunks (SAT) and of the brain by means of femoral puncture.

In the study of the SAT the Doppler detected stenosis or occlusion with a sensitivity of 91.4% and a specificity of 92.3% and, therefore, a positive predictive value (PPV) of 86.4%. 75% of the occlusions were diagnosed with three false positives (which were in fact critical stenoses above 95% instead of occlusion). As regards the evaluation of the transcranial Doppler (TCD), the sensitivity of the Doppler scan to detect stenoses above 50% is situated at 79%, with a PPV of 93%. For diffuse atheromatosis, however, sensitivity is 92.8%, and specificity is 93%.

Findings agree with those offered by other studies conducted in our area using this technique, and show the reliability of this technique carried out in our Neurosonology laboratory. We therefore believe that Doppler echography of the SAT and TCD can be used for achieve an initial evaluation of cerebrovascular pathologies.