BACKGROUNDTo investigate the methods of dynamic enhanced multi-slice spiral CT in evaluation of blood flow patterns of solitary pulmonary nodules (SPNs) with enhancement.

METHODSSeventy-eight patients with SPNs (≤4 cm) with strong enhancement underwent dynamic multi-slice spiral CT (Marconi Mx8000) scan before and after contrast enhancement by injecting contrast material with a rate of 4 mL/s. For the 40 patients in protocol one, one scan was obtained every 2 seconds during 15-45 and 75-105 seconds after injection, while for the 38 patients in protocol two, one scan was obtained every 2 seconds during 11-41 and 71-101 seconds. For all the patients, one scan was obtained every 30 seconds during 2-9 minutes. The section thickness was 2.5 mm for lesions ≤3 cm and 5 mm for lesions > 3 cm. Standard algorithm was used in the image reconstruction. Precontrast and postcontrast attenuation on every scan was recorded. The perfusion, peak height, ratio of peak height of the SPN to that of the aorta and mean transit time were calculated.

RESULTSThe peak height, perfusion, ratio of peak height of the SPN to that of the aorta and mean transit time in malignant SPNs were 34.85 Hu±10.87 Hu, 30.37 ml/(min*100 g)±11.14 ml/(min*100 g), 13.78%± 3.96% , 14.19 s±6.19 s respectively in protocol one, while those in protocol two were 36.62 Hu±10.75 Hu, 30.01 ml/(min*100 g)±8.10 ml/(min*100 g), 14.70 %±4.71%, 13.91 s±4.82 s respectively. No statistically significant differences were found between the peak height (t= 0.673, P=0.503), perfusion (t= 0.152 , P=0.880), ratio of peak height of the SPN to that of the aorta (t= 0.861, P=0.393) and mean transit time (t= 0.199, P=0.843) in malignant SPNs measured in protocol one and those measured in protocol two. All mean transit time in protocol two (36/36) were obtained, but only part of them (25/32) were obtained in protocol one.

CONCLUSIONSDynamic enhanced multi-slice spiral CT is a non-invasive method for quantitative evaluation of blood flow patterns of SPNs with enhancement and scans beginning at 11 seconds after injection of contrast material is suggested.