Palmaroproximal-palmarodistal oblique (PaPr-PaDiO) radiographs are regularly obtained for full evaluation of the navicular bone (NB). Despite their routine use, different acquisition techniques are described.
A recent article was published in the Equine Veterinary Journal that was titled, “Caudal foot placement superior to toe elevation for navicular palmaroproximal-palmarodistal-oblique image quality.” It was authored by Manon W.J. Peeters, Jasmine J. Thursby, Hannah E. Watson and Dagmar Berner.
The aim of this in vitro experiment was to determine optimal foot placement and beam angle for obtaining PaPr-PaDiO views.
A convenience sample of 26 disarticulated forelimbs were placed in six different positions using a leg press to mimic the weight-bearing position. In each position, navicular PaPr-PaDiO images were obtained with eight different beam angles. The resulting 1,248 radiographs were graded for their diagnostic quality and the compacta spongiosa demarcation of the navicular bone.
Diagnostic quality and compacta-spongiosa demarcation was graded higher for feet positioned caudally and angles between 40° and 45°. Elevation of the toe significantly decreased the navicular bone palmar border angle (elevated mean: 40.66, SD: 4.46, non-elevated mean: 42.06, SD: 4.70) (p < 0.01), but seemed to have no obvious positive influence on radiographs.
Caudal foot placement seems to improve image quality of the navicular PaPr-PaDiO view. The standard beam angle of 45° appears to be the favorable angle for acquisition. Elevation of the toe—standard in most commercially available navicular skyline cassette holders—does not influence the obtained image quality.