Purpose
To compare four contrast material injection protocols for dual-energy (DE) computed tomography pulmonary angiography (CTPA) in patients with suspected acute pulmonary embolism (PE) with regard to quality of the DE iodine map and absolute pulmonary blood volume (PBV) values as well as image quality of the pulmonary angiography.
Methods and Materials
One reader retrospectively evaluated four different groups of contrast agent injection protocols consisting of 60 patients each: group 1: 60ml@5ml/s; group 2: 50ml@5ml/s; group 3: 50ml@4ml/s; group 4: 40ml@3ml/s.
All examinations were performed on a 3rd generation dual-source CT system (SOMATOM Force,
Siemens Healthineers) with otherwise identical settings.
Patients with pathologies hampering DE data evaluation were excluded.
Subjective image quality of CTPA and iodine maps (five-point scale: 1=excellent; 5=non-diagnostic),
total PBV,
attenuation in the pulmonary artery (PA) with calculated contrast-to-noise ratio (CNR) were compared.
Results
Overall, data from 165 patients was included (Fig. 1 and 2; groups 1-4 [n]: 40, 41, 43, 41). Mean subjective quality of iodine maps was rated significantly lower in group 4 (2.0±0.7) compared to groups 1-3 (p
Conclusion
DE CT for acute PE provides high subjective CTPA image quality irrespective of contrast injection protocol,
with only slightly inferior subjective quality for low flow rates (group 4).
The low volume/low flow protocol (group 4) resulted in inferior DE-specific data (iodine map,
PBV),
while the moderate volume/moderate flow protocol (group 3) showed acceptable iodine map quality,
but poor PBV values.
References
Petritsch, B, et al. "Diagnosis of pulmonary artery embolism: comparison of single-source CT and 3rd generation dual-source CT using a dual-energy protocol regarding image quality and radiation dose." RöFo-Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren. Vol. 189. No. 06. © Georg Thieme Verlag KG, 2017.
Kerl, JM, et al. "Triphasic contrast injection improves evaluation of dual energy lung perfusion in pulmonary CT angiography." European journal of radiology 80.3 (2011): e483-e487.
Thieme, SF, et al. "Dual-energy CT for the assessment of contrast material...
