Collimator optimization and collimator-detector response compensation in myocardial perfusion SPECT using the ideal observer with and without model mismatch and an anthropomorphic model observer
| Autor: | Eric C. Frey, Jonathan M. Links, Michael Ghaly |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Image formation
Observer (quantum physics) Image quality Computer science Population Image processing Sensitivity and Specificity 01 natural sciences Article 030218 nuclear medicine & medical imaging law.invention 03 medical and health sciences 0302 clinical medicine law 0103 physical sciences Image Processing Computer-Assisted Radiology Nuclear Medicine and imaging Computer vision education Projection (set theory) Image resolution Tomography Emission-Computed Single-Photon education.field_of_study Radiological and Ultrasound Technology 010308 nuclear & particles physics business.industry Detector Myocardial Perfusion Imaging Collimator Artificial intelligence business Perfusion |
| Zdroj: | Physics in Medicine and Biology. 61:2109-2123 |
| ISSN: | 1361-6560 0031-9155 |
| Popis: | The collimator is the primary factor that determines the spatial resolution and noise tradeoff in myocardial perfusion SPECT images. In this paper, the goal was to find the collimator that optimizes the image quality in terms of a perfusion defect detection task. Since the optimal collimator could depend on the level of approximation of the collimator-detector response (CDR) compensation modeled in reconstruction, we performed this optimization for the cases of modeling the full CDR (including geometric, septal penetration and septal scatter responses), the geometric CDR, or no model of the CDR. We evaluated the performance on the detection task using three model observers. Two observers operated on data in the projection domain: the Ideal Observer (IO) and IO with Model-Mismatch (IO-MM). The third observer was an anthropomorphic Channelized Hotelling Observer (CHO), which operated on reconstructed images. The projection-domain observers have the advantage that they are computationally less intensive. The IO has perfect knowledge of the image formation process, i.e. it has a perfect model of the CDR. The IO-MM takes into account the mismatch between the true (complete and accurate) model and an approximate model, e.g. one that might be used in reconstruction. We evaluated the utility of these projection domain observers in optimizing instrumentation parameters. We investigated a family of 8 parallel-hole collimators, spanning a wide range of resolution and sensitivity tradeoffs, using a population of simulated projection (for the IO and IO-MM) and reconstructed (for the CHO) images that included background variability. We simulated anterolateral and inferior perfusion defects with variable extents and severities. The area under the ROC curve was estimated from the IO, IO-MM, and CHO test statistics and served as the figure-of-merit. The optimal collimator for the IO had a resolution of 9-11 mm FWHM at 10 cm, which is poorer resolution than typical collimators used for MPS. When the IO-MM and CHO used a geometric or no model of the CDR, the optimal collimator shifted toward higher resolution than that obtained using the IO and the CHO with full CDR modeling. With the optimal collimator, the IO-MM and CHO using geometric modeling gave similar performance to full CDR modeling. Collimators with poorer resolution were optimal when CDR modeling was used. The agreement of rankings between the IO-MM and CHO confirmed that the IO-MM is useful for optimization tasks when model mismatch is present due to its substantially reduced computational burden compared to the CHO. |
| Databáze: | OpenAIRE |
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