Special angulated projections in coronary arteriography: A confusion in terminology

Abstract

In recent years a number of reports (1-1 1) have pointed out the importance of supplementing conventional oblique projections of the coronary arteries with cranial and caudal angulated projections to minimize foreshortening and overlap of vessels and to improve examination of eccentric coronary artery lesions. Two of these reports provide statistical data on the value of routine use of these projections. Greatly improved diagnostic information was obtained in 46% of studies of the left anterior descending coronary artery (1) and in 54% of studies analyzing the whole coronary arterial tree (2).These angulated projections have been obtained using a number of different x-ray systems, viz: serial film changers with either lateral or overhead x-ray tubes ( 1 , [3][4][5]; an undertable x-ray tube with a cradle in which the patient is propped up 30" with wedges or pillows (4); an undertable x-ray tube coupled to an overhead image intensifier that can be angled from 30" cranially to 15" caudally (General Electric System); C-arms (4, 6); U-arm systems with horizontally rotating isocentric tables (2,7-9); and parallelogram systems ( 10, 1 1). There is little doubt that C-arm, U-arm, and parallelogram systems are the most flexible and convenient in obtaining these special projections.This varied methodology has resulted in a confusing array of terms to describe the views obtained. These include half-axial ( I ) and axial (12); angulated views in the sagittal plane (6); lordotic (3. 5); caudocranial and craniocaudal projections (CCI, and CCII) (8); cranial and caudal angulated oblique views (2); longitudinal angulated projection and superior oblique left anterior oblique projection. Angulation of the x-ray beam is also specified in different ways. Thus there is a need for a) a simpler terminology for all projections and b) a uniform method of specifying angulation of the x-ray beam. NAMING THE PROJECTIONSIn conventional terminology x-ray projections are named either from the position of the imaging device (image intensifier, film changer, etc.) relative to the patient or

Specification of angulated projections in coronary arteriography

“…Confusing and arbitrary terminology has come into use to describe these projections and the editorial presented earlier in this issue (1) has discussed this. Because a number of different x-ray systems are being used, some of which rotate the x-ray table or the patient or both, the precise projection obtained with the different systems may not be immediately obvious.…”

A decade or more of cranial and caudal angled projections in coronary arteriography—another look

“…We proposed a simplification by returning to established conventional radiological terminology, where the projection is labeled by the direction of the X-ray beam, ie, caudo-cranial or cranio-caudal [17,18]. Even so, these terms are still a "mouthful" in day-to-day use and very often have been shortened to "cranial" for caudo-cranial angle and "caudal" for cranio-caudal angle, ie, labeling the projection by the position of the camera rather than that of the X-ray tube.…”