An automatic delineation method for bone marrow absorbed dose estimation in (89)Zr PET/CT studies.

Area of Science:

• Nuclear Medicine
• Radiopharmaceutical Dosimetry
• Medical Imaging Analysis

Background:

• Accurate estimation of red bone marrow (RM) activity concentration and absorbed dose is crucial in (89)Zr positron emission tomography/computed tomography (PET/CT) studies.
• Manual delineation of volumes of interest (VOI) in lumbar vertebrae (LV) is time-consuming and subject to variability.
• Development of automated methods is needed for efficient and reproducible RM dosimetry.

Purpose of the Study:

• To develop and validate an automatic delineation method for estimating RM activity concentration and absorbed dose.
• To compare the accuracy and efficiency of an automated VOI method with manual delineation.
• To assess the feasibility of using an active contour approach for RM dosimetry in (89)Zr PET/CT.

Main Methods:

• Five patients with advanced colorectal cancer underwent serial (89)Zr-cetuximab PET/CT scans.
• Low-dose CT data were used to generate lumbar vertebrae (LV) VOI manually and automatically using an active contour method.
• RM activity was determined by mapping CT-derived RM VOI onto PET scans.
• Residence times and self/total RM absorbed doses were calculated using OLINDA/EXM 1.1.

Main Results:

• High correlations (r² > 0.85) were observed between manual and automated VOI methods for RM activity concentrations and total absorbed doses.
• The automated method yielded values within 5% of the manual method on average.
• The active contour-based automated method demonstrated high accuracy and efficiency.

Conclusions:

• An automated and efficient VOI method based on an active contour approach was successfully developed.
• This automated method enables accurate estimates of RM activity concentrations and total absorbed doses in (89)Zr PET/CT studies.
• The developed method offers a valuable tool for improving RM dosimetry in targeted radionuclide therapy.