99m technetium pyrophosphate scintigraphy with cadmium zinc telluride cameras is a highly sensitive and specific imaging modality to diagnose transthyretin cardiac amyloidosis

Transthyretin cardiac amyloidosis (attr) is a rare, but underdiagnosed, cardiomyopathy. traditionally diagnosed invasively, attr can be diagnosed with non-invasive 99mtechnetium pyrophosphate (99mtc-pyp) planar scintigraphy. non-planar imaging has not been validated for attr diagnosis. here, we develop and validate a cadmium zinc telluride (czt) protocol for diagnosing attr. forty-three subjects (24 attr, 19 non-attr) were imaged with philips dual-head anger (planar) and general electric czt cameras. myocardial uptake was quantified by heart-to-contralateral (h/cl) ratios. czt scans were quantified by two readers blinded to planar h/cl, with one repeating blinded quantification. using the previously validated diagnostic threshold (h/cl ≥ 1.5), sensitivity and specificity of czt scintigraphy was measured. mcnemar’s test and pearson’s correlation coefficient were calculated. among subjects (76.7% male, age 77 ± 9), there was no significant difference in proportion of attr-positive identification between modalities. there was high correlation between czt and planar h/cl ratios (r = 0.92, p < 0.0001), with low intra- [icc = 0.89 (0.80-0.94)] and inter-observer [icc = 0.80 (0.65-0.89)] variability. czt scintigraphy had 100% sensitivity and specificity for diagnosing attr. 99mtc-pyp czt imaging is as highly sensitive and specific diagnosing attr as planar imaging. these findings are clinically salient given the emergence of disease-modifying attr therapies, as it could expand diagnostic capability.