Journal article
Automated model-based quantitative analysis of phantoms with spherical inserts in FDG PET scans
Medical physics (Lancaster), Vol.45(1), pp.258-276
01/2018
DOI: 10.1002/mp.12643
PMCID: PMC5836792
PMID: 29091269
Abstract
Quality control plays an increasingly important role in quantitative PET imaging and is typically performed using phantoms. The purpose of this work was to develop and validate a fully automated analysis method for two common PET/CT quality assurance phantoms: the NEMA NU-2 IQ and SNMMI/CTN oncology phantom. The algorithm was designed to only utilize the PET scan to enable the analysis of phantoms with thin-walled inserts.
We introduce a model-based method for automated analysis of phantoms with spherical inserts. Models are first constructed for each type of phantom to be analyzed. A robust insert detection algorithm uses the model to locate all inserts inside the phantom. First, candidates for inserts are detected using a scale-space detection approach. Second, candidates are given an initial label using a score-based optimization algorithm. Third, a robust model fitting step aligns the phantom model to the initial labeling and fixes incorrect labels. Finally, the detected insert locations are refined and measurements are taken for each insert and several background regions. In addition, an approach for automated selection of NEMA and CTN phantom models is presented. The method was evaluated on a diverse set of 15 NEMA and 20 CTN phantom PET/CT scans. NEMA phantoms were filled with radioactive tracer solution at 9.7:1 activity ratio over background, and CTN phantoms were filled with 4:1 and 2:1 activity ratio over background. For quantitative evaluation, an independent reference standard was generated by two experts using PET/CT scans of the phantoms. In addition, the automated approach was compared against manual analysis, which represents the current clinical standard approach, of the PET phantom scans by four experts.
The automated analysis method successfully detected and measured all inserts in all test phantom scans. It is a deterministic algorithm (zero variability), and the insert detection RMS error (i.e., bias) was 0.97, 1.12, and 1.48 mm for phantom activity ratios 9.7:1, 4:1, and 2:1, respectively. For all phantoms and at all contrast ratios, the average RMS error was found to be significantly lower for the proposed automated method compared to the manual analysis of the phantom scans. The uptake measurements produced by the automated method showed high correlation with the independent reference standard (R
≥ 0.9987). In addition, the average computing time for the automated method was 30.6 s and was found to be significantly lower (P ≪ 0.001) compared to manual analysis (mean: 247.8 s).
The proposed automated approach was found to have less error when measured against the independent reference than the manual approach. It can be easily adapted to other phantoms with spherical inserts. In addition, it eliminates inter- and intraoperator variability in PET phantom analysis and is significantly more time efficient, and therefore, represents a promising approach to facilitate and simplify PET standardization and harmonization efforts.
Details
- Title: Subtitle
- Automated model-based quantitative analysis of phantoms with spherical inserts in FDG PET scans
- Creators
- Ethan J Ulrich - Department of Biomedical Engineering, The University of Iowa, Iowa City, IA, USAJohn J Sunderland - Department of Radiology, The University of Iowa, Iowa City, IA, USABrian J Smith - Department of Biostatistics, The University of Iowa, Iowa City, IA, USAImran Mohiuddin - Department of Radiation Oncology, The University of Iowa, Iowa City, IA, USAJessica Parkhurst - Department of Radiation Oncology, The University of Iowa, Iowa City, IA, USAKristin A Plichta - Department of Radiation Oncology, The University of Iowa, Iowa City, IA, USAJohn M Buatti - Department of Radiation Oncology, The University of Iowa, Iowa City, IA, USAReinhard R Beichel - Department of Internal Medicine, The University of Iowa, Iowa City, IA, USA
- Resource Type
- Journal article
- Publication Details
- Medical physics (Lancaster), Vol.45(1), pp.258-276
- Publisher
- United States
- DOI
- 10.1002/mp.12643
- PMID
- 29091269
- PMCID
- PMC5836792
- ISSN
- 0094-2405
- eISSN
- 2473-4209
- Grant note
- P30 ES005605 / NIEHS NIH HHS P30 CA086862 / NCI NIH HHS R01 CA169072 / NCI NIH HHS U01 CA140206 / NCI NIH HHS
- Language
- English
- Date published
- 01/2018
- Academic Unit
- Radiology; Electrical and Computer Engineering; Biostatistics; Physics and Astronomy; Radiation Oncology; Neurosurgery; Otolaryngology; Holden Comprehensive Cancer Center
- Record Identifier
- 9983997302702771
Metrics
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