Comparison of free breathing versus breath-hold in perfusion imaging using dynamic volume CT.

OBJECTIVES

To compare two scanning protocols (free breathing versus breath-hold) for perfusion imaging using dynamic volume computed tomography (CT) and to evaluate their effects on image registration.

MATERIAL AND METHODS

Forty patients underwent dynamic volume CT for pancreatic perfusion analysis and were randomly assigned to either a shallow-breathing (I) or breath-hold (II) group. Both dynamic CT protocols consisted of 17 low-dose volumetric scans. Rigid image registration was performed by using the volume with highest aortic attenuation as reference. All other volumes were visually matched with the pancreatic lesion serving as the volumetric region of interest. The overall demand for post-processing per patient was calculated as the median of three-dimensional vector lengths of all volumes in relation to the relative patient origin. The number of volumes not requiring registration was recorded per group.

RESULTS

Registration mismatch for groups I and II was 2.61 mm (SD, 1.57) and 4.95 mm (SD, 2.71), respectively (P < 0.005). Twenty-eight volumes in group I (8.2%) and 47 volumes in group II (14.1%) did not require manual registration (P = 0.014).

CONCLUSION

Shallow breathing during dynamic volume CT scanning reduces the overall demand for motion correction and thus may be beneficial in perfusion imaging of the pancreas

MAIN MESSAGES

• Shallow breathing during perfusion CT scanning reduces the overall demand for motion correction. • Shallow breathing may be beneficial in perfusion imaging of the pancreas. • Image registration is crucial for CT perfusion imaging.