State-of-the-art incremental CT scan protocols in the dog for the optimal use of contrast medium

A lot of veterinarians have access to computed tomography and appreciate th is imaging technique to improve diagnosis, prognosis and therapy. In this s tudy the enhancement of vessels and parenchymal organs was studied by means of 46 referred dogs. lopamidol was the only used contrast medium which sho wed no side effects. The obtained Hounsfield units (HU) were compiled in ti me-density-curves and compared to find out the best enhancing protocol. The advantage of using a multilevel CT injector could be demonstrated when aut omatic injection and administration by hand were compared. Injection flow f or the automatic power injector could be calculated by use of the heart rat e times the proportional blood volume of each region of the body. The diffe rence of rapid injection of contrast medium compared to a slower infusion b ecame obvious during CT-enhanced examination of the brain. Overdosage of co ntrast medium was without effect to the blood brain barrier. Contrast enhan ced tissue of the neck, the brachial plexus, and the cranial mediastinum sh owed the comparable results of time-density-curves as found in the head. A larger amout of contrast medium of 3 ml/kg body weight was necessary to cov er the long distances of the abdominal vessels and the well perfused parenc hymal: organs. Injection rate was found to be optimal at 1.5 to 2.0 ml/s in a middle-seized dog. The influence of the narcotic drugs on the circulatio n could be neglected because of underdosage of anaesthetics. The proposed C T examination protocols shall function as a proper guide for practical use of the technique. The advance of correct positioning, choise of scan range and preset parameters, proper use of contrast medium, and the value of best windowing and image documentation was emphazised. The diagnostic output is lowered if differences of positioning and use of technical parameters in c omparision to human medicine are not taken into consideration.