Today's Veterinary Practice provides comprehensive information to keep every small animal practitioner up to date on companion animal medicine and surgery as well as practice building and management.
| SMALL ANIMAL PELVIC RADIOGRAPHY
UÊOnce the pelvic limbs have been extended, which typically requires the patient be adequately sedated, internally rotate the femurs so that they are parallel to one another and the x-ray table.
UÊWhen properly aligned, the patella for each pelvic limb will be centered within the trochlear groove oÛiÀÊÌhiÊ`iÃÌ>lÊvimÕÀ°Ê-iVÕÀiÊÌhiÊ`o}½ÃÊ«ilÛiVÊlimLÃÊ in this position using tape around the femurs at the liÛilÊovÊÌhiÊÃÌivliÊjoinÌÊFigures 2A and 2B®°
Collimation 1ÃiÊÌhiÊÃ>miÊ«ÀoVi`ÕÀiÃÊvoÀÊÃiÌÌin}ÊÌhiÊVollim>ÌoÀÊli}hÌÊ as described earlier for lateral images.
Figure 2. Extended-Leg Ventrodorsal Radiographs of Pelvis A
UÊCranial Border: The cranial border of the collima- ÌoÀÊli}hÌÊ "6®ÊÃhoÕl`ÊLiÊ«l>Vi`ÊVÀ>ni>lÊÌoÊÌhiÊili>VÊ crest. Palpate the iliac crests and place the cranial edge of the collimator light just cranial to this level.
UÊCaudal/Distal Border: The caudal/distal border of the collimator light should be placed just distal to the stifle joints to allow the proximal crura to be included in the image.
UÊLateral Borders\Ê loÃiÊÌhiÊVollim>ÌoÀÊli}hÌÊ l>ÌiÀ- ally so the light is next to the skin on both the right >n`ÊlivÌÊÃi`iÃ°Ê ``Ê>ÊvilmÊm>ÀkiÀÊ,É ®ÊvoÀÊi`inÌivÞ- ing the right or left side prior to exposure.
ADDITIONAL RADIOGRAPHIC VIEWS Frog-Leg Ventrodorsal Images Dogs and cats with severe coxofemoral degenerative joint disease or fractures of the pelvis, femoral head/ neck, or femur are not physically able to extend their femurs in the standard extended-leg ventrodorsal posi- tion. In this case, a frog-leg ventrodorsal image can be used for initial assessment. It addition, in dogs or cats with capital physeal frac-
tures of the femoral head, extending the limbs into the routine position can actually reduce the fracture and render the fracture indistinguishable from the normal limb.
should be used to confirm the fracture.
(A) Lateral view of a dog that has been placed in dorsal recumbency in a V-trough (positioning trough) with the pelvis being pulled caudal to the V- trough. The pelvic limbs have been extended and are taped at the level of the stifle joints for appropriate positioning of the pelvic limbs relative to the pelvis, table, and each other.
Positioning 1ÃiÊ >Ê 6-ÌÀoÕ}hÊ ÌoÊ hil«Ê kii«Ê ÌhiÊ «>Ìiin̽ÃÊ ÛiÀÌiLÀ>lÊ VolÕmnÊ>n`ÊÃÌiÀnÕmÊ>li}ni`ÊFigure 3®°Ê ÃÊÜiÌhÊÃÌ>n- dard ventrodorsal images, avoid superimposed artifacts caused by the V-trough by placing the entire pelvis past the edge of the trough onto the x-ray table, which also decreases geometric magnification.
In this case, the frog-leg ventrodorsal image
B
C
D
E
(B) Another view of dog positioned for an extended-leg ventrodorsal radiograph. (C) Routine radiograph of the pelvis from the dog in A and B. Note the symmetry of the size and shape of the obturator foramina. (D and E) Obliqued or rotated radiographs where the pelvis was positioned incorrectly; note the asymmetry of the obturator foramina (arrows). For D, the right side of the dog's pelvis should pulled up (away from the table slightly) to correct this positioning abnormality. For E, the left side of the dog's pelvis should be pulled up (away from the table slightly) to correct this positioning abnormality.
50 Today's Veterinary Practice January/February 2012