J Nucl Med. 2007; 48 (Supplement 2):420P
Instrumentation & Data Analysis: Image Generation
Image Generation Posters |
Increased spatial and temporal resolution of gated myocardial perfusion images (GMPI) achieved by multi-pinhole SPECT (MP-SPECT)
John Koss1,
Peter Steele1 and
Dennis Kirch1
1 Western Cardiology Associates, Westminster, Colorado
1754
Objectives: The sensitivity and resolution characteristics of rotational SPECT systems limit the available dynamic information from GMPI. The increased sensitivity of MP-SPECT improves the temporal resolution capability supporting more accurate LV functional measurements. This study defines the practical limits in terms of patient dosages and acquisition times for GMPI studies of LV performance by MP-SPECT. Methods: Using a 9-pinhole SPECT system, we acquired GMPI studies on 5 pts over a range of dosages (9,18,27 and 35 mCi of tetrofosmine) and acquisition times (1,2,5,10 and 15 minutes). This data was acquired in list-mode format to facilitate reprocessing to establish spatial and temporal resolution characteristics needed for reliable measurement of LV dynamics in terms of ejection fraction, rates, compliance and synchrony. The GMPI were segmented into 16 and 32 frames per R-to-R interval and automated middle-of-the-wall tracking analysis was applied without operator intervention. Wall thickness measurements were referenced to this midwall track and regressive correction was used to obtain inner wall volume estimates. Results: This data establishes that accurate measurements of LV performance by MP-SPECT can be achieved at up to 32 frames per R-to-R using 5 min acquisition times with 36 mCi. At 16 frames per second the required acquisition times for relaible measurement are 2, 5 and 10 min for dosages of 27, 18, and 9 mCi respectively. The exception to this is wall thickening which is most dramatically effected by respirational motion. Our analysis indicates that motion correction (MC) on a breath-by-breath basis will be a necessary prerequisite for accurate wall thickness measurements. Conclusions: These results establish that temporally and spatially resolved GMPI by MP-SPECT protocol can approach echo in terms of rapid, accurate measures of the most important LV dynamic performance indicators and that MP-SPECT is compatible with the pharmacologic stress maneuvers which are essential to the detection and management of CAD. Also, GMPI by simultaneous dual-isotope MP-SPECT of Tc and Tl together retains the ability to measure flow mediated aspects of CAD within the same protocol but success in any meaningful attempt to measure wall thickening requires MC for respirational movement.
