Penalized maximum-likelihood reconstruction for improving limited-angle artifacts in a dedicated head and neck PET...

Area of Science:

• Medical Imaging
• Nuclear Medicine
• Biomedical Engineering

Background:

• Positron emission tomography (PET) has limited spatial resolution in head and neck cancer management.
• Detecting small lymph node involvement (<10 mm) is crucial for accurate staging and treatment.

Purpose of the Study:

• To develop and evaluate a penalized maximum-likelihood (PML) reconstruction method for a dual-panel, high-resolution PET system.
• To mitigate image artifacts caused by limited angular coverage in dual-panel PET systems.
• To improve the detection of small lesions in head and neck cancer.

Main Methods:

• Utilized cadmium zinc telluride (CZT) detectors with cross-strip readout in a dual-panel PET system.
• Implemented a PML reconstruction algorithm penalizing dissimilarity with a prior low-resolution image.
• Incorporated an image-based resolution model into the regularization process.
• Evaluated performance using computer simulations with varying hot sphere sizes.

Main Results:

• PML reconstruction eliminated lesion elongation artifacts for 6-mm and 8-mm hot spheres with regularization strength γ ≥ 0.02.
• Achieved higher contrast recovery coefficients (CRC) for hot spheres compared to standard maximum-likelihood reconstruction and low-resolution whole-body PET.
• Demonstrated improved performance across all tested hot sphere sizes (3-8 mm).

Conclusions:

• The developed PML reconstruction effectively mitigates limited-angle artifacts in dual-panel PET data.
• This method enhances the potential of high-resolution dual-panel PET systems for improved head and neck cancer management.
• The system shows promise for more accurate detection of small lymph node metastases.