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Variability of perceived defect size in virtual lung scintigraphy
J S Magnussen1, P Chicco, A W Palmer
1Department of Nuclear Medicine, Concord Hospital, New South Wales, Australia.
Summary
Physicians often underestimate pulmonary embolism (PE) defect sizes, especially in the right lower lobe. Improved accuracy in diagnosing PE may be achieved with anatomical guides for defect size classification.
Area of Science:
- Nuclear Medicine
- Radiology
- Medical Imaging
Background:
- Pulmonary embolism (PE) diagnosis relies on identifying mismatched segmental or subsegmental defects.
- Classifying defect size (small, moderate, large) is crucial but poorly understood.
- Limited published data exists on the perception and classification of these defect sizes.
Purpose of the Study:
- To investigate the perception and classification of lung defect sizes in a virtual scintigraphic model.
- To address the lack of information regarding the recognition and sizing of defects in pulmonary embolism diagnosis.
Main Methods:
- Modeled lung segmental anatomy using CT, cadavers, and anatomical tests.
- Simulated photon emission, scatter, and attenuation within virtual lungs.
- Created 100% segmental lesions in eight projections for blinded reporting by four nuclear medicine physicians on two occasions.
Main Results:
- Physicians underestimated defect sizes, with 50% reported as 75%-100% of a segment.
- Accuracy of estimation was only 50%, with fair intraobserver agreement (weighted kappa 0.34-0.60).
- Defects in the right lower lobe were most frequently underestimated.
Conclusions:
- Segmental defect sizes are consistently underestimated, particularly in the right lower lobe.
- The accuracy of defect size estimation is suboptimal, highlighting potential diagnostic challenges.
- Utilizing a guide to segmental anatomy could improve accuracy and reduce variability in reporting PE defects.