Reduced Native T1 Values of Wrist Tissues in Transthyretin Cardiac Amyloidosis

<b>Background/Objectives:</b> Carpal tunnel syndrome (CTS) may signal extracardiac amyloid deposition years before transthyretin cardiac amyloidosis (ATTR-CA). This study investigated potential alterations of wrist tissue T1 values in ATTR-CA patients. <b>Methods:</b> Patients with ATTR-CA and healthy volunteers underwent 1.5T wrist MRI using a gradient echo sequence. Manual contouring of the transverse carpal ligament (TCL), median nerve (MN), sheaths of the flexor carpi tendons (SFCT), subcutaneous fat (SCF), muscle of the thenar eminence (MTE), and global wrist (GCW) was performed by two readers. Native T1 values were compared between groups. <b>Results:</b> Thirty-six patients with ATTR-CA (mean age, 78 ± 9 years; 32 men) and 69 volunteers (43 ± 14 years; 24 men) were evaluated. Mean native T1 values of TCL, MN, SFCT, SCF, and GCW were significantly lower in patients than in volunteers (<i>p</i> < 0.005 for all). Multivariable regression adjusted for age and sex confirmed these associations. SCF T1 was significantly lower in patients with CTS symptoms (885 [762-1080] ms) than in asymptomatic patients (1041 [949-1267] ms, <i>p</i> = 0.04). The highest area under the curve (AUC) for detecting CA was obtained for SFCT (AUC = 0.85; 95% CI 0.77-0.93). <b>Conclusions:</b> Patients with transthyretin cardiac amyloidosis show a significant reduction in the native T1 of wrist tissues compared with controls. These preliminary findings suggest that wrist T1 mapping may serve as a non-invasive marker of peripheral amyloid involvement, but require further validation in larger, age-matched, histologically validated studies.