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SALINE chasers are widely used in CT applications, particularly for CT angiography in human medicine ( Orlandini and others 2006 , Tatsugami and others 2007 , Kim and others 2008 ). In veterinary medicine, experimental studies have reported on saline chaser techniques for CT angiography in cattle ( Lee and others 2010a , b ) and dogs ( Lee and others 2007 ). The use of a saline chaser results in greater efficiency of the contrast medium by avoiding accumulation of the contrast medium at the injection site. This increased efficiency can be used for enhancement ( Lee and others 2010b ) or to reduce the volume of the contrast medium used ( Lee and others 2010a ).
A reduction in the quantity of the contrast medium used can be economically beneficial, particularly in cattle, which require a large volume of contrast medium. Studies demonstrated a 30 per cent reduction in the dose of contrast medium on using saline chasers without decreasing vascular enhancement ( Lee and others 2010a ). However, saline chasers need to be injected at the same rate as the contrast medium. Few studies have investigated the effect of different injection rates of saline chasers on contrast enhancement ( Lee and others 2007 , Kim and others 2008 , Schindera and others 2008 , Coursey and others 2009 , Behrendt and others 2010 ). Two reports focused on the effect of saline chasers injected at different rates in vivo in dogs ( Lee and others 2007 ) and human beings ( Kim and others 2008 ). While Lee and others (2007) performed two saline chaser techniques, one at the same injection rate as that of the contrast medium and the other at half the rate of the contrast medium, Kim and others (2008) did not involve a control group that would receive contrast medium without saline chasers.
Understanding the effect of different saline chaser techniques on the pattern of contrast enhancement is important to optimise contrast administration. Thus, this study aimed to determine the effect of varying injection rates of saline chasers on intravascular contrast enhancement on dynamic CT in cattle. The maxillary artery and sagittal sinus were chosen for measurements in the present study, taking into account the diameter of the...