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This Article Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Branderhorst, W. Articles by Beekman, F. PubMed Articles by Branderhorst, W. Articles by Beekman, F.

Cardiac images obtained with focusing pinhole SPECT are barely influenced by extra-cardiac activity

¹ Image Sciences Institute, UMC Utrecht, Utrecht, Netherlands

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Objectives: Ultra-high resolution SPECT can be obtained with focusing multi-pinhole collimators (FMPC) that focus to a central field-of-view (CFOV). Here we investigate if high tracer uptake outside the CFOV influences reconstructed tracer distributions inside the CFOV for the case of myocardial perfusion scans, where gallbladder and liver exhibit high tracer uptake.

Methods: An FMPC-based small animal SPECT system (U-SPECT-II, MILabs, The Netherlands) with a stationary detector setup was simulated. Its CFOV with the mouse collimator tube is approximately 12 mm in diameter and 8 mm in length. This is sufficiently large to contain a mouse heart. Using a digital mouse thorax phantom representing a Tc-99m tetrofosmin distribution, projection data with and without activity in the gallbladder and liver were generated. Reconstructions were performed with ML-EM (80 iterations) and OS-EM (16 subsets, 5 iterations). Image profiles over the entire left ventricular wall were compared to assess changes in myocardial activity due to liver and gallbladder activity.

Results: Relative to reconstructions with no liver and gallbladder activity present, peaks of image profiles representing centers of the myocardial wall deviate only 3.1% in average. The maximum deviation was 9.2%. For OS-EM these values were 3.1% and 9.1% respectively.

Conclusions: Reconstructed tracer density in the myocardium is only slightly influenced by the high activity usually found in the nearby liver and gallbladder, even for the worst case investigated here, with only a single position of the pinhole focus. This finding may eliminate the need to extend the field-of-view at the cost of count yield from the structure of interest.

This Article Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Branderhorst, W. Articles by Beekman, F. PubMed Articles by Branderhorst, W. Articles by Beekman, F.