Pulmonary nodule size evaluation with chest tomosynthesis and CT: a phantom study

We compared digital tomosynthesis (TOMO) and chest CT in terms of assessing the sizes of nodules located in zones where evaluation by simple radiography is limited.

A total of 48 images comprising phantom nodules of four sizes in six different locations were used. Nodule size measurement errors for measurements using TOMO and CT images compared with the actual size from each observer were calculated. The inter- and intraobserver repeatability of the measured values and the agreement between the two techniques were assessed using the method described by Bland and Altman.

The mean measurement errors for all of the nodules and four observers were -0.84 mm [standard deviation (SD), 0.60 mm] on TOMO and -0.18 mm (SD, 0.71 mm) on CT images. The mean measurement errors for the different observers ranged from -1.11 to -0.55 mm for TOMO and from -0.39 to 0.08 mm for CT. Assessing the agreement between nodule size measurements using TOMO and CT resulted in mean measurement errors of -0.65 mm, with a 95% limit of agreement of -2.53 to 1.22 mm for comparison of TOMO with CT.

Our results suggest that nodule sizes obtained using TOMO and chest CT are comparable, even for nodules located in areas where the size measurement is limited on simple radiography.

TOMO and CT can be used interchangeably, even for nodules located in a blind area on simple radiography.