Does registration of PET and planning CT images decrease interobserver and intraobserver variation in delineating...

Area of Science:

• Oncology
• Medical Imaging
• Radiation Therapy

Background:

• Accurate tumor volume delineation is crucial for effective radiation therapy planning in non-small-cell lung cancer (NSCLC).
• Fusion of Positron Emission Tomography (PET) and Computed Tomography (CT) images aids in precise tumor localization.
• Assessing the impact of image registration on the consistency of tumor contouring is essential for clinical application.

Purpose of the Study:

• To compare the consistency of tumor volume delineation using registered versus side-by-side PET/CT image sets.
• To evaluate the impact of image registration on both interobserver and intraobserver variability in tumor contouring.

Main Methods:

• 19 NSCLC patients underwent 18-fluorine-deoxyglucose (FDG)-PET/CT imaging.
• Two radiation oncologists contoured tumor volumes using registered and non-registered (side-by-side) image sets.
• A third physician re-contoured volumes using both registered and non-registered methods to assess intraobserver variability.
• Quantitative analysis used the concordance index; qualitative analysis graded differences in projected images.

Main Results:

• Median interobserver concordance was significantly higher with registered images (70%) compared to non-registered (61%, p <0.05).
• Median intraobserver concordance was higher with registered/registered contours (71%) versus registered/non-registered (58%, p=0.10).
• Qualitative analysis showed fewer significant differences in tumor delineation with registered images for both interobserver and intraobserver assessments.

Conclusions:

• Registration of FDG-PET and planning CT images significantly improves consistency in tumor volume delineation.
• This enhanced consistency in contouring can lead to more accurate and reliable radiation therapy planning for NSCLC patients.