Computed tomography angiography (CTA) requires IV application of iodine-based contrast agents. There are several medical conditions in which application is not advisable or even feasible, especially for elective examinations. Novel techniques such as monoenergetic reconstructions from dual-energy computed tomographic (CT) data have been shown to increase radiation attenuation of gadolinium (Gd)-based contrast agents in a phantom model. Therefore, the purpose of the present investigation was to evaluate the technical feasibility and image quality of clinical spectral CTA with a Gd-based contrast agent.
Eleven consecutive patients with common indications for thoracic CTA and contraindications for iodine-based contrast agents were examined using clinical routine doses (0.2 mmol/kg) of Gd-based contrast agent with spectral CT. Monoenergetic reconstructions of the spectral data set were computed.
We performed 11 Gd-enhanced CTAs: 9 aortic angiographies, 1 coronary angiography, and 1 angiography of the pulmonary arteries. Image quality of the monoenergetic reconstructions with 40 keV (monoE40) was considered diagnostic by 2 experienced radiologists in each patient; the conventional CT reconstructions did not reach diagnostic image quality. MonoE40 reconstruction resulted in a substantial, ∼2-fold increase of intravascular Gd attenuation compared with the conventional images (P<0.0001). No relevant change of attenuation was observed for the myocardium or the skeletal muscle.
With spectral CT and reconstruction of monoenergetic images with extrapolated 40 keV, Gd-based contrast agent thoracic angiography with clinical doses of Gd is technically feasible. Gd-based CTA seems a valuable alternative in patients with contraindications for iodine-based contrast media.
Departments of *Diagnostic and Interventional Radiology
‡Vascular and Endovascular Surgery
§Cardiology, Klinikum rechts der Isar, Technical University of Munich, Munich
†Technical University of Munich, Garching/Munich, Germany
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. All patients who underwent this technique were examined after intense discussion and interdisciplinary indication as a healing trial. All examinations were clinically indicated. Gd-DOTA was applied in an off-label-use. This was discussed with the patients, and they fully agreed to the examination with an augmented consent for Gd-based CTA examination. We hereby publish our retrospectively gathered data. This retrospective work is in accordance with local ethical standards; the methodology of this work has been approved by the local ethics committee. For this type of study formal consent is not required.
This is a retrospective study; all patients underwent clinically indicated CT examination. All personal details were anonymized for evaluation and publication. Patients gave informed augmented consent for CTA with Gd. For this retrospective registry study with no identifiable patient data, no informed study consent is required.
P.B.N. receives financial support through the German Department of Education and Research (BMBF) under grant IMEDO (13GW0072C). The remaining authors declare no conflicts of interest.
Correspondence to: Jonathan Nadjiri, MD, Department of Diagnostic and Interventional Radiology, Klinikum rechts der Isar, Technical University of Munich, Ismaninger Str. 22, Munich 81675, Germany (e-mail: firstname.lastname@example.org).