A randomised controlled trial comparing three clinical administration strategies in spectral detector CT pulmonary angiography with low contrast medium dose.

OBJECTIVES

To compare vascular attenuation (VA) with three strategies for administering a low contrast medium (CM) dose in dual-layer spectral detector CT pulmonary angiography (CTPA).

METHODS

Patients were prospectively randomised into control- or one of two experimental groups. Control group patients received CM (350 mgI/mL) diluted 1:1 with saline. Experimental group B received CM (350 mgI/mL) with low flow. Experimental group C received CM with low concentration (140 mgI/mL). Virtual monoenergetic images at 40 and 55 kiloelectron Volt (keV) were reconstructed. Objective examination quality (OEQ) i.e., VA, noise, and signal-to-noise ratio, was measured and subjective examination quality (SEQ) was rated at three anatomical levels: in the pulmonary trunk (PT), the interlobar arteries and the posterior basal segmental arteries.

PRIMARY OUTCOME

VA in PT at 40 keV.

SECONDARY OUTCOMES

OEQ and SEQ across all anatomic levels.

RESULTS

A total of 328 patients were randomised. 112 vs 115 and 101 were analysed in the control (A) vs experimental groups (B and C), respectively. There were no differences in VA in PT between the groups: A vs B (p = 0.96), B vs C (p = 0.14), and A vs C (p = 0.18). Group C showed higher VA across all anatomical levels. There were no differences in SEQ.

CONCLUSION

There was no difference in the attenuation in the PT between the dilution-, low flow-, and low concentration groups. However, the low concentration group showed higher attenuation in the pulmonary arteries when all anatomical levels were assessed.

KEY POINTS

Question Contrast medium reduction may be accomplished with dilution, low flow, or low concentration. However, the effect of the different strategies on vascular attenuation is unknown. Findings There was no difference in pulmonary trunk attenuation between the three strategies on spectral detector CT pulmonary angiography. Clinical relevance Low contrast medium dose spectral detector CT pulmonary angiography may be implemented with the administration strategy of the unit's own choice.