A new method for scintigraphic quantification of deposition and clearance in anatomical regions of the human nose

OBJECTIVES: To develop methods for absolute quantification of the deposition of 99mTc-labeled aerosols and powders in well-defined anatomical regions of the nose, and to enable accurate comparisons of different nasal administration techniques in the same individual. METHODS: The volunteer was seated and positioned relative to the scintillation camera field of view by means of a fixation frame. After nasal administration, a dynamic series of images was acquired for 32 min with a lateral direction of view. The images were corrected for photon attenuation by the use of a lateral transmission image acquired before the delivery of aerosols or powders. Marker images, obtained with a line source fixed to a balloon and kept for a short while against the palate as well as with a point source held on anatomical landmarks, were used to co-register the scintigraphic images to sagital sections through a three-dimensional magnetic resonance (MR)-image series. The MR set was used to define the inner nose contour and the nasal regions used for quantification. RESULT: Attenuation correction factors ranged from 1.1 to 1.7 in different parts of the nasal cavity. Alignment of the markers on the teeth and palate with the sagital MR images could be reproduced with accuracies of 1.2 and 1.7 mm, respectively. CONCLUSION: The new method provides reliable quantification of the deposition in anatomic regions that can be defined in MR images. Accurate co-registration and quantification are essential when comparing distribution and clearance patterns for different administration techniques.