Francesco Molinari MD, Presenter: Nothing to Disclose

Paul Felloni MD, Abstract Co-Author: Nothing to Disclose

Francois Pontana MD, Abstract Co-Author: Nothing to Disclose

Nunzia Tacelli MD, Abstract Co-Author: Nothing to Disclose

Teresa Santangelo, Abstract Co-Author: Nothing to Disclose

Martine J. Remy-Jardin MD, PhD, Abstract Co-Author: Research Grant, Siemens AG

To evaluate the characteristics of pulmonary blood volume (PBV) on dual-source, dual-energy chest CT examinations.

Eligibility to this study required (a) the absence of respiratory disease after a diagnostic work-up including a dual-source, dual-energy chest CT angiographic examination; (b) rated with an excellent image quality (i.e., excellent quality of vascular opacification; no respiratory motion artifacts); and (c) obtained on the same CT unit (Definition Flash, Siemens Healthcare). Over a 2 year-period, 42 patients (mean age: 43.05 yr) fulfilled these criteria, enabling analysis of PBV in the following conditions: (a) collimation: 32x2x0.6 mm; rotation time: 0.28 s; pitch: 0.5; caudo-cranial acquisition without modulation of milliamperage; (b) administration of 80 mL of a 40% contrast agent followed by 40 mL of a diluted contrast agent (70% NaCl; 30% iodine) at a flow rate of 4mL/s,. Qualitative analysis was based on visual assessment. Quantitative analysis measured the (a) iodine concentration per lung (IPIPE software; Siemens) and (b) regional distribution of iodine after semi-automatic division of each lung into 18 areas (OSIRIX).

The iodine (I) concentration did not significantly differ between the right (R) (1.54 ±0.43 mg I/mL) and left (L) (1.53 ±0.41 mg I/mL) lungs with a mean attenuation of 41.35 HU (R lung) and 41.14 HU (L lung) (p=0.49). Three regional gradients of attenuation were observed : (a) infero-superior (p<0.001), linked to the conditions of examination (mean ∆ : -6.23 in the R lung ; -5.96 in the L lung), ; (b) postero-anterior (p<0.001) due to gravity (mean ∆ : 11.92 in the R lung ; 15.93 in the L lung) et (c) cortico-medullary (p<0.001) (mean ∆: -9.35 in the R lung ; -8.37 in the L lung). The intensity of the postero-anterior (r=0.42; p<0.001) and cortico-medullary (r=0.58; p<0.0001) gradients was correlated to the overall iodine concentration. In the studied population, 7% of anatomical segments (59/840) showed artifacts hampering perfusion analysis, related to beam-hardening artifacts (RS1; RS2) or cardiac motion (RS5, LS5).

Distribution of PBV is influenced by physiological gradients and scanning conditions.

This study provides quantitative information on lung perfusion in the conditions of standard evaluation of normal subjects.

Molinari, F, Felloni, P, Pontana, F, Tacelli, N, Santangelo, T, Remy-Jardin, M, Impact of Scanning Conditions in the Evaluation of Pulmonary Blood Volume with Dual-energy CT: Results in 42 Subjects.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13027161.html