Abdominal Positioning RVT: Chapter 18

Learning Objectives: Abdomen & Soft Tissue Understand radiographic concerns associated with the abdomen Properly and safely position a small animal for two common radiographic views, with the ability to: Measure accurately Center the x-ray beam appropriately Image with correct borders Properly position the patient Understand alternate views Identify normal abdominal anatomy, including major differences between cats and dogs

Small Animal Abdomen: Anatomy

SA Abdomen: Radiographic Concerns Similar tissue densities & multiple organ systems GI gas & fat provide contrast Generally use a higher kVp and lower mAs needed Try for higher _____ and lower ______ to shorten exposure May need two films per view in deep-chested dogs Can average measurements on smaller animals Heel effect! Contrast media often required

SA Abdomen: Radiographic Concerns Use nonmanual restraint whenever possible Wear PPE at all times Measure in the position to be radiographed Thickest part: Usually last rib (T_ _ ) Expose at end of _______________ (during pause) Allows maximum space for abdominal organs

Radiographing the Abdomen: Positioning

Lateral Abdomen – Dog vs Cat

Abdominal Positioning: Lateral Lateral recumbency Sternum & spine on same plane ___________ to the image receptor Aim is symmetry & superimposition Forelimbs pulled cranially; hind limbs caudal Foam wedge needed? Right lateral separates kidneys better

Abdominal Positioning: Lateral Left lateral is preferable in vomiting patients Gas in pylorus can highlight a foreign body Left lateral may be required in contrast studies L/R marker at ventral aspect Collimation must include: Cranial margin- Full diaphragm and heart apex (T7) Caudal margin- Greater trochanter (coxofemoral joint)

Liver Mass

Gastric Trichobezoar

Gastric Dilitation & Volvulus (GDV) “Double bubble”

Lateral Positioning: Confirmation Superimposition of: Vertebral foramina Spinous processes Coxofemoral joints Ribs

Abdominal Positioning: Ventrodorsal Measure at about 13th rib Dorsal recumbency Restraint device? Must pull forelimbs cranial; hindlimbs in natural position Imagine a straight line connecting nose & caudal midline * DV can be used as alternative if animal is compromised by VD Dog Cat

Abdominal Positioning: Ventrodorsal Collimation must include: Cranial margin- Full diaphragm (T9) Caudal margin- Greater trochanter (coxofemoral joint) Central ray positioning differs between cat & dog Central beam is slightly more caudal on cats Ensure marker is on the correct side!

V/D Positioning: Confirmation Spinous processes are aligned in the center of vertebral bodies Sternum and spine are super imposed Abdominal symmetry

Abdomen: Lateral Oblique Used to evaluate male urinary/reproductive tracts Better visualization of penis Free leg must be retracted out of the field of view!

Abdomen: Modified Lateral Used when radiographing the entire male urinary tract Hind limbs pulled cranially so they don’t overlap urethra or bladder *Used mainly for contrast

Abdominal Anatomy: Notes Fat animals image better than emaciated ones Fat serves as a contrasting opacity Many normal structures hidden radiographically Ureters, urethra, adrenals, pancreas, etc. Abnormalities can make them visible! Liver – very large organ! Normally lies within ribs Best evaluated via lateral radiograph Stomach – Normally within rib cage (include caudal ribs in radiograph) Food images as granular material of mixed opacity Can be 2-3 times larger after a meal Gas rises and fluid moves with gravity

Chocolate Ingestion

Abdominal Anatomy: Notes Spleen- usually to the left of midline; lateral to the stomach Kidneys- right is more cranial than left Should find the left within the lumbar spinal region Bladder- very caudal in the abdomen

Bladder Stones