Effect of Positioning on Coelomic Radiography with and without Contrast in the Green Iguana (Iguana iguana)
A prospective study was performed in 12 green iguanas (Iguana iguana) to compare the radiographic appearance of coelomic viscera. Five radiographic projections (views) of the coelom were obtained: dorsoventral, right lateral vertical beam, left lateral vertical beam, right lateral horizontal beam, and left lateral horizontal beam. One week later, the same radiographic projections were obtained after oral administration of barium. In 4 of the 12 green iguanas, an additional vertical beam ventrodorsal view was obtained. In comparing lateral projections, lung, liver, and gonads were best imaged in horizontal beam lateral projections, before distention of the stomach with barium, whereas the gastrointestinal tract including the colon was best visualized in vertical beam lateral projections. The shape and size of the cardiac silhouette was considered equivalent between analogous lateral projections in most green iguanas (10 [83%] of 12). In comparing ventrodorsal and dorsoventral projections, the ventrodorsal projections improved visibility of the cardiac silhouette and lung in 4 (100%) of 4 green iguanas, while reducing cardiac length. Dorsoventral projections were preferred for the evaluation of the gastrointestinal tract. This study demonstrates that radiographic beam orientation and patient position result in obvious radiographic differences of the iguanid coelom and that projections are not interchangeable.Abstract
Positioning a sedated green iguana (Iguana iguana) for a standard right and left lateral horizontal beam radiographs. Radiolucent positioning device (foam pad) was used to elevate the iguana above table and center the x-ray beam (A). The limbs were taped to provide an unobstructed view from coelom (B).
Dorsoventral (DV) (A) and ventrodorsal (VD) (B) radiographs of the coelom of a juvenile male green iguana (Iguana iguana). In VD, the ribcage expands, improving pulmonary inflation. In VD, cardiac length was judged mildly shorter and cardiac margins were sharper in all green iguanas. In the subject shown here, the cardiac silhouette is additionally more opaque in VD, and this observation was not repeated in other green iguanas for which this projection was available. Inset: heart (red), liver (yellow), and stomach (green).
Right lateral radiographs of the cranial coelom in a juvenile green iguana (Iguana iguana): (A) right lateral horizontal beam (RHB), (B) right lateral vertical beam (RVB), and (C) RVB positive contrast gastrointestinal study. The liver (arrows) is best outlined in horizontal beam projection before distension of the stomach with barium.
Lateral radiographs of the coelom of a juvenile female green iguana (Iguana iguana). Although left lateral horizontal beam (LHB) (A) and right lateral horizontal beam (RHB) (B) are nearly identical, vertical beam (VB) views show striking differences, particularly relating to the gastrointestinal tract. The angular shape of the fundus (black *) was only observed in LVB (C). Dorsal bowing of the pyloric antrum (arrow) was observed only in RVB (D). The urinary bladder (white *) could not be outlined in survey images, but in this series is opacified by residual iohexol administered in a separate study the week before imaging.
Right lateral horizontal beam (RHB) (A) and right lateral vertical beam (RVB) (B) radiographs of a juvenile male green iguana (Iguana iguana). The gonads (arrows) are distinctly seen in (A), but effaced in (B).
