Quantitative comparison of normal limits for regional wall motion and thickening for MRI and MPS

Objectives We aim to characterize normal limits using quantitative 3D myocardial wall thickening and motion on cardiac Magnetic Resonance Images (CMRI) with technetium-99mTc-sestamibi myocardial perfusion Single-Photon Emission Computed Tomographic (MPS) images.

Methods 23 consecutive subjects with normal left ventricular systolic function on visual image assessment of CMR and rest/stress MPS performed within 2 hours after CMR were analyzed. Rest MPS and CMRI scans were compared. 3D endocardial and epicardial surfaces were automatically determined with QGS algorithm on MPS. On MRI, 3D myocardial boundaries were fitted and visually corrected. Polar map 3D motion and thickening measurements were transformed into the standard 17-segment representation and 90^th percentile normal limits for thickening and motion were computed.

Results Percent thickening increased from the basal to distal segments on both MRI and MPS (Table). For wall thickening, on MRI, (255/289) 90% of the segments values with positive visual scores (> 0) were higher than the 90^th percentile limits. MPS resulted in 92% of segments with positive scores higher than the the 90^th percentile limits. For wall motion analysis, on MRI, 90% of the segments (261/289) with scores > 0 were outside the 90^th percentile. On MPS, 75% of the segments (218/289) with scores > 0 were outside the 90^th percentile.

Conclusions Normal limits for wall motion/thickening have been established between MRI and SPECT. There are significant differences between these values in some regions and therefore these values could not be interchanged.