Wei Song MD, Abstract Co-Author: Nothing to Disclose

Xin Sui MD, Presenter: Nothing to Disclose

Zheng Yu Jin MD, Abstract Co-Author: Nothing to Disclose

Huadan Xue MD, Abstract Co-Author: Nothing to Disclose

The objective was to compare the nodule volumes measured in low-dose CT (LDCT)with filtered back projection (FBP) versus ultra-low-dose CT (ULDCT) with sinogram-affirmed iterative reconstruction (SAFIRE).

Forty-two patients (mean [SD] age, 53.1[8.9] years) were erolled in this study. Clinical indications for chest CT included a follow-up study of primary or metastatic lung malignancy, a solitary pulmonary nodule on the radiograph. Clinical diagnoses were lung cancer (n=18), breast cancer (n=15), thyroid carcinoma (n=9). All the patients underwent LDCT (reference parameters 120 kV, 50 mAs) and ULDCT(reference parameters 80 kV, 5 mAs) with dual-source flash 128-slice CT system (SOMATOM Definition Flash, Siemens Healthcare, Germany).The average body mass index (BMI) of patients was 24.1(±2.6)kg/m2.Radiation dose was recorded. All the CT images were reconstructed with filtered back projection (FBP) for LDCT data and with SAFIRE for ULDCT data. 101 solid nodules were identified by 2 different radiologists by a consensus panel. Automated nodule volume measurements were performed by using computer-assisted volume measurement software (Syngovia, Siemens Healthcare).

The mean effective doses were 0.13±0.02 mSv and 2.01±0.31 mSv for ULDCT and LDCT, respectively. There are 25 nodules (smaller than 4mm by RECIST), 68 nodules (between 4mm and 8mm by RECIST) and 8 nodules (size greater than 8mm RECIST). The volume of the indentified nodules were compared between the 2 groups by use of the Wilcoxon’s rank test, and no significant differences were observed (Z=-1.375, P=0.175).

In comparison with LDCT, SAFIRE of ULDCT enables significant reduction in radiation dose for lung screening, while no affecting solid nodule measurement. It is safe to convert LDCT FBP protocols to ULDCT SAFIRE for volume of solid lung nodule follow up.

ULDCT for lung cancer screening retains potential for the lung nodule volume follow-up.

Song, W, Sui, X, Jin, Z, Xue, H, Pulmonary Nodule Volume in Ultra-low-dose CT with Sinogram-affirmed Iterative Reconstruction.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14019733.html