Technical note: Can photon-counting CT improve PET/CT's quantitative accuracy?

Area of Science:

• Medical Imaging Physics
• Radiological Sciences
• Nuclear Medicine Technology

Background:

• Linear attenuation coefficients (LACs) in PET/CT are typically derived from energy-integrating detector CT (EID-CT), but are inaccurate with iodine contrast.
• Photon counting detector CT (PCD-CT) offers potential for improved LAC accuracy.

Purpose of the Study:

• To evaluate if PCD-CT can enhance the quantitative accuracy of PET/CT scans.
• To assess the impact of PCD-CT on LAC accuracy, especially in the presence of iodine contrast.

Main Methods:

• Two experiments were conducted: CT-only phantom studies and combined PET/CT phantom studies.
• EID-CT and PCD-CT were used to derive LACs from phantoms simulating human tissues, including bone and iodinated blood.
• PET images were reconstructed using LACs from both EID-CT and PCD-CT, with quantitative accuracy assessed via recovery coefficients (RC).

Main Results:

• PCD-CT-derived LACs showed a maximum error of 3%, compared to up to 18% error for EID-CT.
• PET quantitative accuracy improved with PCD-CT, indicated by more consistent recovery coefficients (mean RC 101.0% vs. 103.8% for EID-CT).
• Image consistency in both body and head orientations was enhanced using PCD-CT.

Conclusions:

• PCD-CT provides accurate LAC information for PET reconstruction within a single acquisition.
• This technology holds promise for improving the quantitative performance of PET/CT imaging.