Charbel Saade MS, Presenter: Nothing to Disclose

Hussain Al-Mohiy, Abstract Co-Author: Nothing to Disclose

Mukbil H. Hourani MD, Abstract Co-Author: Nothing to Disclose

To investigate opacification of the pulmonary vasculature during CTPA using a patient-specific contrast formula and exponentially decelerated contrast media injection rate.

CTPA was performed on 150 patients with suspected PE using a 256 channel computed tomography scanner and a dual barrel contrast injector. Patients were randomly assigned to two equal protocol groups: protocol A, the department’s conventional protocol, employed a patient-specific contrast formula based on measured patient cardiovascular dynamics. Protocol B involved the use of a patient-specific contrast formula combined with exponentially decelerated contrast media injection rate. Both protocols used a 50 mL saline flush at 4.5 mL/s and a craniocaudal scan direction. Patient age and gender were equally distributed across both groups. The mean cross-sectional opacification profile of eight central and eleven peripheral pulmonary arteries and veins were measured for each patient and arteriovenous contrast ratio (AVCR) calculated for each lung segment. Protocols were compared using Mann-Whitney U non-parametric statistics. Jackknife alternative free-response receiver operating characteristic (JAFROC) analyses were used to assess diagnostic efficacy. Inter-observer variations were investigated using Kappa methods

A number of pulmonary arteries demonstrated increases in opacification (p<0.02) for protocol B compared with A whilst opacification in the heart and all veins was reduced in protocol B (p<0.03). Subsequently, increased AVCR in protocol B compared with A was observed at all anatomic locations (p<0.0002) where this ratio could be calculated. An increase in JAFROC figure of merit (p<0.0002) and inter-observer variation was observed with protocol B compared with A with the latter metric increasing from (κ = 0.3) to (κ = 0.73) respectively. Mean contrast volume was reduced in protocol B (29±4 mL) compared to A (33±9 mL). 

Significant improvements in visualisation of the pulmonary vasculature can be achieved with a low contrast volume CT acquisition using an exponentially decelerated contrast media injection rate and a patient-specific contrast formula

Matching contrast injection timing with vessel dynamics significantly improves vessel opacification and reduces contrast dose in the assessment of pulmonary embolism during computed tomography pulmonary angiography.

Saade, C, Al-Mohiy, H, Hourani, M, Exponentially Decelerated Contrast Media Injection Rate Combined with A Novel Patient-specific Contrast Formula Reduces Contrast Volume Administration During Computed Tomography Pulmonary Angiography.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14002567.html