J Nucl Med. 2007; 48 (Supplement 2):426P
Instrumentation & Data Analysis: Instrumentation
Instrumentation Posters |
Comparison of respiratory sensors and its compliance for respiratory gating in emission tomography
Axel Martínez-Möller1,
Ralph Bundschuh1,
Michael Riedel1,
Nassir Navab2,
Sibylle Ziegler1,
Markus Schwaiger1 and
Stephan Nekolla1
1 Nuklearmedizinische Klinik der TU München, München, Germany;
2 Computer Aided Medical Procedures and Augmented Reality, TU München, Munich, Germany
1775
Objectives: Respiratory motion in the thorax and upper abdomen contributes to the degradation of image quality and observed spatial resolution in emission tomography. To account for it, gating techniques have been developed which rely on the acquisition of a respiratory signal. We compared the signals obtained from 4 different sensors and its compliance for respiratory gating. Methods: Four sensors were evaluated: elastic belt placed around the abdomen, spirometer measuring flow of respired air, thermoprobe measuring the temperature of respired air and infrared stereovision system tracking the motion of thoracic markers. All four sensors were evaluated according to its usability and reliability. Initial measurements were performed on 10 healthy volunteers asked to breathe normally but also to hold their breath, cough, etc. Based on these results, the elastic belt and stereovision system were selected for usage in 6 gated PET acquisitions for CAD patients examined using 13N-Ammonia in a Siemens Biograph16 PET/CT scanner. Results: Both the spirometer and the thermoprobe were discarded after the measurements with volunteers because of their low reliability; moreover, the thermoprobe signal had an intrinsic delay to the respiratory motion. The elastic belt and the stereovision system worked reliably, providing curves well suited for respiratory gating. The correlation coefficient between both signals in the 6 PET acquisitions was 0.75±0.26, resulting in the same respiratory gate for 85±14% of the time, offering therefore equivalent results. The signal provided by the elastic belt showed occasional changes of the baseline during the acquisition, requiring the development of adapted gating algorithms. The stereovision system was technically demanding, but offered the advantage of measuring bulk patient motion in addition to respiratory motion. Conclusions: The elastic belt and the stereovision system provided the most reliable results. Altogether, the elastic belt showed the best combination of usability and reliability, and the stereovision system should be favored only when other patient motion is to be measured in addition to respiratory motion.
