The internal examination of a human organ (3) is made by means of an ultrasonic probe (2) inserted into the organ (3), analogue echo signals from the probe being converted to digital signals (8) which are then stored in a digital computer (10) where they are manipulated to produce a variety of three-dimensional representations of the interior of the organ for display on a terminal (12) or as hard copy (13).

Methods and apparatus for the examination and treatment of internal organs

The accuracy and the reliability of extracranial vertebral Doppler flow (continuous wave Doppler sonography) for the detection of intracranial vertebrobasilar lesions was studied prospectively in twenty-one patients with brainstem disturbances and/or coma. The Doppler findings were compared with cerebral angiography. Doppler sonography was highly reliable for both detection and exclusion of high grade intracranial vertebrobasilar lesions. The pathognomonic Doppler finding was an abrupt deceleration of the blood column during systole and stoppage or even reflux during diastole. The same blood flow alterations were found in two additional illustrative cases having therapeutically or brain-death induced blockages of the vertebral arteries. The pathophysiologic mechanisms of flow disturbances and the limitations of Doppler sonography in this area are discussed.

https://www.ahajournals.org/doi/pdf/10.1161/01.STR.16.5.848

Non-invasive diagnosis of intracranial lesions in the vertebrobasilar system. A comparison of Doppler sonographic and angiographic findings.

Ultrasonic duplex scanning of the vertebral artery has a sensitivity of 0.80 and a specificity of 0.83 for the detection of an obstructive lesion of 50% or more at the site of the ostium. For the subclavian arteries these values are respectively 0.73 and 0.91. For both vessels the test has a very high negative predictive value of respectively 0.96 and 0.97. Therefore duplex ultrasound scanning is a reliable test in screening patients suspected of multi-level atherosclerotic disease of the extracranial cerebral vessels. The problem remains in classifying the degree of stenosis. In the case of the vertebral artery the sample volume of the pulsed Doppler is usually too large in relation to the vessel diameter. In the case of the subclavian and innominate artery one of the main problems is the range of the pulsed Doppler system. A subclavian steal syndrome is easily diagnosed without any special test.

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Ultrasonic duplex scanning in atherosclerotic disease of the innominate, subclavian and vertebral arteries. a comparative study with angiography

A technique for the imaging of vertebral arteries at their origins and along the longitudinal extracranial course is described. The results of the examination of 108 normal vertebral arteries are shown. The vertebral artery could be distin guished in the pretransverse and intertransverse segment C5-C6 in 100%. The average diameter of the vessel was 3.81 ± 0.46 mm on the right and 3.88 + 0.47 on the left side. The average maximal systolic velocity was 43.0 ± 8.9 cm/s on the right and 43.3 ± 9.6 on the left side. In 81% of the cases the vertebral origin could be located on the right and in 65% of the cases on the left side. The technical quality of visualization, especially of the vertebral origin, was greatly influenced by the depth of the examined structure. Examples of pathologic find ings, such as hypoplasia, stenosis, and occlusion, demonstrate the practical pos sibilities of this noninvasive method.

Duplex ultrasonography of vertebral arteries: examination, technique, normal values, and clinical applications.

The reliability of the echo-Doppler (duplex) system for the visualization of the vertebral arteries was evaluated in 304 patients, in which 588 vertebral arteries had been investigated Of these, 545 (9269 per cent) arteries, either normal or diseased, were successfully visualized However, the origin of the vertebral artery from the subclavian artery was localized in only 354 vessels (60 per cent of those visualized) Angiography was available for comparison in 33 arteries The overall accuracy and the sensitivity of the duplex were 6364 per cent and 3846 per cent, respectively; they attained 8667 per cent and 8333 per cent in the vertebral arteries visualized from their origin, (a site early and most commonly involved by the atherosclerotic process) As the vertebral arteries can be visualized with a 92 per cent success rate, their examination should become a routine part of the duplex cerebrovascular study In order to accurately detect diseased vertebral arteries, their origin from the subclavian artery should be localized

The echo-Doppler (duplex) system for the detection of vertebral artery occlusive disease: comparison with angiography.

A 30 channel directional pulsed Doppler imaging system (MAVIS) has been used to produce images of the vertebral artery. The technique of imaging the subclavian artery in the suparaclavicular fossa, the origin of the vertebral artery and the section of this vessel up to the foramen in the transverse process of the sixth cervical vertebra is described. Further segments of the vertebral artery appearing between the cervical transverse processes can also be imaged if disease in the mid portion of the vessel is suspected. Confirmation of the identity of the insonated artery is gained from its position on the image in relation to the subclavian and common carotid arteries and from its characteristic flow velocity wave forms. Examples of the typical antero-posterior images obtained are presented. Of 60 vertebral arteries scanned, 56 have been imaged successfully. Insufficient patients have undergone conventional contrast angiography to allow data on diagnostic accuracy but the unsuccessful scans may well have been in those with occluded vessels. Application of the technique to the investigation of patients with either vertebro-basilar symptoms or the subclavian steal syndrome is discussed.

H.B. Meire

Papers

A technique for imaging the vertebral artery using pulsed doppler ultrasound