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

Hengquan Zhang, Yuli Wang, Jinyi Qi, Shiva Abbaszadeh

Research output: Contribution to journalArticlepeer-review


Positron emission tomography (PET) suffers from limited spatial resolution in current head and neck cancer management. We are building a dual-panel high-resolution PET system to aid the detection of tumor involvement in small lymph nodes ([Formula: see text]10 mm in diameter). The system is based on cadmium zinc telluride (CZT) detectors with cross-strip electrode readout (1 mm anode pitch and 5 mm cathode pitch). One challenge of the dual-panel system is that the limited angular coverage of the imaging volume leads to artifacts in reconstructed images, such as the elongation of lesions. In this work, we leverage a penalized maximum-likelihood (PML) reconstruction for the limited-angle PET system. The dissimilarity between the image to be reconstructed and a prior image from a low-resolution whole-body scanner is penalized. An image-based resolution model is incorporated into the regularization. Computer simulations were used to evaluate the performance of the method. Results demonstrate that the elongation of the 6-mm and 8-mm diameter hot spheres is eliminated with the regularization strength γ being 0.02 or larger. The PML reconstruction yields higher contrast recovery coefficient (CRC) of hot spheres compared to the maximum-likelihood reconstruction, as well as the low-resolution whole-body image, across all hot sphere sizes tested (3, 4, 6, and 8 mm). The method studied in this work provides a way to mitigate the limited-angle artifacts in the reconstruction from limited-angle PET data, making the high-resolution dual-panel dedicated head and neck PET system promising for head and neck cancer management.

Original languageEnglish (US)
Pages (from-to)165016
JournalPhysics in medicine and biology
Issue number16
StatePublished - Aug 21 2020


  • Artifacts
  • Cadmium
  • Computer Simulation
  • Head and Neck Neoplasms/diagnostic imaging
  • Humans
  • Image Processing, Computer-Assisted/methods
  • Likelihood Functions
  • Phantoms, Imaging
  • Positron-Emission Tomography
  • Tellurium
  • Zinc

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