Optimization of image reconstruction of 123I DAT SPECT with a LEGP collimator
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
In SPECT, diagnoses based on quantitative measurements may be uncertain due to high noise levels and low spatial resolution. 123I DAT SPECT has been shown to have a relatively high sensitivity and specificity, but improving image quality could potentially increase these values even further, especially for early cases with parkinsonian syndromes. The aim of the study was to optimise the reconstruction protocol for 123I DAT SPECT with a LEGP collimator, using a resolution recovery algorithm included in the iterative reconstruction, and compare to images reconstructed without resolution recovery. The optimization concentrated on critical frequency of the post-reconstruction Butterworth filter and the number of reconstruction iterations. Monte Carlo simulations of a morphological brain phantom with typical DAT SPECT uptake were used for this part of the study. From contrast-to-noise diagrams, it was found that a critical frequency of 0.50 cm-1 (power factor 8) was the most optimal of the studied filters. The optimal number of OSEM iterations was evaluated by a radiologist, specialized in nuclear medicine, and 8 iterations with 6 subsets were chosen. A group of 20 subjects diagnosed with Parkinson’s disease (PD) were then be compared to a group of 20 healthy controls, with respect to uptake ratios for caudate nucleus, putamen and the whole striatum (background region: whole cortex or the occipital lobe). Uptake ratios were calculated using the software Exini DAT for images reconstructed both with and without resolution recovery. It was found that the group differences were highly significant both with and without resolution recovery. However, in putamen, where early stages of PD first manifests, the group significance of uptake ratios improved from 7.2E-14 to 8.2E-15 (background: occipital lobe) or 2.4E-14 to 8.4E-16 (background: whole cortex) when using resolution recovery. A higher spatial resolution seems to be an advantage for quantitative evaluation of 123I DAT SPECT.
Place, publisher, year, edition, pages
2015. , 35 p.
SPECT, I-123, reconstruction, datscan, evolution toolkit, resolution recovery
Medical Image Processing
IdentifiersURN: urn:nbn:se:umu:diva-105043OAI: oai:DiVA.org:umu-105043DiVA: diva2:822961
Subject / course
Examensarbete i teknisk fysik
Master of Science Programme in Engineering Physics
2015-04-01, Universitetsklubben, 13:43 (English)
Larsson Strömvall, Anne, Associate Professor
Tölli, Heikki, PhD
Universitetsklubben i Universumbyggnaden på Umeå Universitet2015-06-172015-06-172015-06-17Bibliographically approved