Imaging features of wild-type transthyretin amyloid cardiomyopathy in gated and non-gated contrast-enhanced CT.

Abstract

Wild-type transthyretin amyloid cardiomyopathy (ATTR-CM) could be common, but its diagnosis is often overlooked. If the imaging features of ATTR-CM can be identified using conventional computed tomography (CT), which is commonly employed in clinical practice, its diagnostic value would be great. This study aimed to assess the imaging features of the condition in conventional non-gated contrast-enhanced CT. We retrospectively analyzed 43 consecutive patients diagnosed with wild-type ATTR-CM and performed a semi-quantitative evaluation of myocardial hypo-enhancement in the portal venous phase of conventional contrast-enhanced CT. A myocardial hypo-enhancement score (MHES) was calculated and compared between patients with ATTR-CM and 43 age-, sex-, height-, and weight-matched controls. Correlations between the score and clinical parameters such as the myocardial extracellular volume fraction (ECV) were also assessed. The MHES was significantly higher in the ATTR-CM group than in the control group (p < 0.01). It was also significantly higher in the high-ECV ATTR-CM subgroup (> 55%) than in the low-ECV ATTR-CM (≤ 55%) subgroup and the control group. There was good agreement between myocardial hypo-enhancement and late enhancement (kappa = 0.43), with 90.4% of the hypo-enhanced segments showing late enhancement. The detection sensitivity of late enhancement segments was higher in gated coronary CT angiography than in non-gated portal venous phase CT (69.2% vs 87.1%, p < 0.01). Wild-type ATTR-CM exhibited a tendency for myocardial hypo-enhancement, predominantly in the basal segments on conventional non-gated contrast-enhanced CT, suggesting an association with myocardial microcirculatory dysfunction. Question Can myocardial hypo-enhancement in non-gated contrast-enhanced CT help diagnose wild-type ATTR-CM, particularly in settings where late iodine enhancement imaging is unavailable? Findings Hypo-enhancement, predominantly in basal segments, was higher in ATTR-CM patients and correlated with ECV and global longitudinal strain, suggesting microcirculatory dysfunction. Clinical relevance Identifying myocardial hypo-enhancement in basal segments on conventional non-gated contrast-enhanced CT may provide a valuable diagnostic clue for ATTR-CM, particularly in facilities lacking LIE imaging, allowing for earlier recognition and potential clinical intervention.