Patterns and Prevalence of Misregistration in 18F-FDG PET/CT
Abstract
Objectives:
In PET/CT, the fusion of form (CT) and function (PET) provides high accuracy in staging, restaging and assessing response to therapy in oncology. Precise alignment between ct and pet components of the study is a prerequisite for accurate fusion. However, misregistration in pet/ct is not uncommon and, when present, may compromise image interpretation, resulting in lesion mislocalization and inaccurate suv quantitation. The purpose of this study was to evaluate patterns and prevalence of misregistration in pet/ct.
Methods:
True whole-body fdg-pet/ct scans, covering from the top of skull to the bottom of the feet, of 100 patients were retrospectively reviewed in nuclear medicine radiology department, saint louis university. Images were acquired on a PET/CT scanner (phillips medical systems) 60 minutes after an intravenous injection of a weight-adjusted dose of 0.14 mCi/kg FDG. A log was kept to measure and record cases of misfusions between the pet and the ct portions as detected on the pet/ct fused images. Six anatomic locations were selected to evaluate for significant Misfusion: arms, head and neck, heart, diaphragm, pelvis and legs. Misregistration was also categorized into non-preventable (ex. Breathing) and preventable (ex. Patient motion). In the current study, misregistration was consi-derd significant if more than 5 mm, the spatial resolution of current pet/ct scanners.
Results:
Of 100 consecutive scans reviewed, significant misfusion: in85% the arms (mean=11.50 mm), the head and neck in 67% (mean=8.36 mm), the heart in 88% (mean=8.11 mm), the diaphragm in 68 % (mean=8.36 mm), the pelvis in 98 % (m=14.52 mm), the legs in 86 % (mean=15.02 mm).
Conclusions:
Significant misregistration was encountered and measurable in 100% of PET/CT studies. It is important to be aware of misregistration in PET/CT resulting from spatial and temporal misalignment between the CT and the PET portions in order to avoid false interpretations of the PET/CT exam.
In PET/CT, the fusion of form (CT) and function (PET) provides high accuracy in staging, restaging and assessing response to therapy in oncology. Precise alignment between ct and pet components of the study is a prerequisite for accurate fusion. However, misregistration in pet/ct is not uncommon and, when present, may compromise image interpretation, resulting in lesion mislocalization and inaccurate suv quantitation. The purpose of this study was to evaluate patterns and prevalence of misregistration in pet/ct.
Methods:
True whole-body fdg-pet/ct scans, covering from the top of skull to the bottom of the feet, of 100 patients were retrospectively reviewed in nuclear medicine radiology department, saint louis university. Images were acquired on a PET/CT scanner (phillips medical systems) 60 minutes after an intravenous injection of a weight-adjusted dose of 0.14 mCi/kg FDG. A log was kept to measure and record cases of misfusions between the pet and the ct portions as detected on the pet/ct fused images. Six anatomic locations were selected to evaluate for significant Misfusion: arms, head and neck, heart, diaphragm, pelvis and legs. Misregistration was also categorized into non-preventable (ex. Breathing) and preventable (ex. Patient motion). In the current study, misregistration was consi-derd significant if more than 5 mm, the spatial resolution of current pet/ct scanners.
Results:
Of 100 consecutive scans reviewed, significant misfusion: in85% the arms (mean=11.50 mm), the head and neck in 67% (mean=8.36 mm), the heart in 88% (mean=8.11 mm), the diaphragm in 68 % (mean=8.36 mm), the pelvis in 98 % (m=14.52 mm), the legs in 86 % (mean=15.02 mm).
Conclusions:
Significant misregistration was encountered and measurable in 100% of PET/CT studies. It is important to be aware of misregistration in PET/CT resulting from spatial and temporal misalignment between the CT and the PET portions in order to avoid false interpretations of the PET/CT exam.