Agreement between SPECT/CT-derived autoplanar imaging and conventional planar imaging in 99mTc-PYP scintigraphy.

PURPOSE: To evaluate the agreement and reproducibility of SPECT/CT-derived AutoPlanar imaging compared with conventional planar imaging in 99mTc-pyrophosphate (99mTc-PYP) scintigraphy for transthyretin amyloidosis cardiomyopathy (ATTR-CM). MATERIALS AND METHODS: We retrospectively analyzed 54 patients with suspected ATTR-CM who underwent 99mTc-PYP scintigraphy. Conventional planar imaging and SPECT/CT acquisition were performed at 1 h and 3 h after tracer injection. AutoPlanar images were generated from reconstructed SPECT/CT datasets. Visual assessment using the Perugini grading scale and semiquantitative evaluation using the heart-to-contralateral chest (H/CL) ratio were compared between conventional planar and AutoPlanar imaging. RESULTS: Exact agreement in Perugini scores between conventional planar and AutoPlanar imaging was observed in 90.7% of patients at 1 h and 98.1% at 3 h, with quadratic weighted κ values of 0.938 and 0.992, respectively. H/CL ratios demonstrated excellent agreement between the two imaging methods, with correlation coefficients of 0.987 at both imaging time points. Using H/CL ratio cutoffs of ≥ 1.5 at 1 h and ≥ 1.3 at 3 h, agreement for H/CL-based positive/negative classification was 98.1% and 96.3%, respectively. CONCLUSION: SPECT/CT-derived AutoPlanar imaging showed excellent agreement with conventional planar imaging for both visual and semiquantitative assessment in 99mTc-PYP scintigraphy. AutoPlanar imaging showed excellent agreement with conventional planar imaging and may serve as an alternative image display method for visual and semiquantitative assessment in 99mTc-PYP scintigraphy.