Tobias De Zordo MD, Presenter: Nothing to Disclose

Klemens Von Luterotti, Abstract Co-Author: Nothing to Disclose

Peter Franz Walter Soegner MD, Abstract Co-Author: Nothing to Disclose

Renate Frank, Abstract Co-Author: Nothing to Disclose

Werner R. Jaschke MD, PhD, Abstract Co-Author: Nothing to Disclose

Gudrun Feuchtner MD, Abstract Co-Author: Nothing to Disclose

Christian Dejaco, Abstract Co-Author: Nothing to Disclose

Newly introduced 128-dual source computed tomography (CT) allows for high-pitch spiral (HPS) and dual energy (DE) pulmonary CT angiography (CTA) with a new selective photon shield filter. Our purpose was to compare HPS CTA and DE CTA with conventional helical pulmonary CTA regarding radiation dose and image quality.

In this retrospective study 110 patients were identified who underwent CT due to clinically suspected pulmonary embolism on an 128-dual source CT (Siemens Somatom Definition FLASH) system (52 pts HPS CT at 100kV and high-pitch, 20 pts DECT at 100/140kV, 38 pts helical CT at 100kV and low-pitch). Twenty pts of each group were matched for body mass index. Effective radiation dose was estimated using dose-length-product (DLP) x conversion factor 0,014. Subjective image quality was evaluated on a 4-point-scale (1 excellent - 4 nondiagnostic). Quantitative image quality was assessed by measuring absolute intravascular CT attenuation values (HU) in a standardized ROI and the corresponding image noise (+-SD of HU) bilateral in 3 central and 4 peripheral pulmonary arteries. DE CTA was evaluated for lung perfusion defects and pulmonary emboli.

Mean effective radiation dose for HPS CTA was with 1.9mSv significant lower (p<0.001) compared to helical CTA 2.6mSv and DE CTA 3.2mSv. Mean subjective image quality scores were not significantly different with 1.3+-0.4 for HPS CTA, 1.2+-0.5 for DE CTA, and 1.4+-0.6 for helical CTA. Mean intrapulmonary CT attenuation and image noise were 451.6 HU and 36.9 SD (HU) respectively for HPS CTA, 353.5 HU and 27.9 SD (HU) respectively for DE CTA, and 377.5 HU and 39.3 SD (HU) respectively for helical CTA. On DECT images 7 patients with pulmonary emboli have shown perfusion defects in the corresponding lung parenchyma. In one patient a triangular perfusion defect was found without corresponding pulmonary embolus.

Comparable image quality for pulmonary CT angiography was obtained by all CT methods. HPS CTA allowed for a significant decrease of radiation exposure and DE CTA allowed for additional lung perfusion assessment.

HPS CT allows for radiation dose savings compared to helical CT while maintaining image quality. DE CTA provides reliable CT angiography and complementary evaluation of perfusion defects.

De Zordo, T, Von Luterotti, K, Soegner, P, Frank, R, Jaschke, W, Feuchtner, G, Dejaco, C, Performance of High-Pitch Spiral and Dual Energy 128 Dual Source CT Pulmonary Angiography in Comparison with Conventional Helical Technique.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9007388.html