This study evaluates the temporal changes in magnetic resonance imaging (MRI) signal intensity (SI) of quadriceps tendon (QT) grafts during the healing period after anterior cruciate ligament reconstruction (ACLR) using the 'Ribbon' surgical technique and compares these findings with the SI of the native ACL. MRI SI of QT grafts was analyzed in a cohort of 75 patients who underwent ACLR using the M-ARS (Medacta Anatomic Ribbon Surgery) technique at 3, 6, 9 and 12 months post-operatively. The anterior-to-posterior cruciate ligament ratio (APR) was calculated for the proximal, middle and distal regions of the ACL graft and compared with the reference APR of the native ACL. Median SI increased between the third and sixth post-operative months across all graft regions, followed by a subsequent decline. The distal segment consistently exhibited a higher APR at all time points. At 3 months, all regions except the proximal one differed significantly from the reference cohort. Notably, at 6 and 12 months, 35% and 22% of patients, respectively, presented values outside the expected range of the reference group. The period between 3 and 6 months after surgery represents a critical phase for graft maturation, with the distal section of the graft showing the slowest remodelling process, likely due to inferior vascularization. Even at 12 months, SI values had not reached those characteristic of the native ACL. This study highlights the clinical relevance of monitoring graft healing via MRI to guide rehabilitation progression and safe return-to-sport timing, emphasizing the critical 3- to 6-month period when graft biomechanical properties are lowest, and remodelling is incomplete, a factor often overlooked in current functional and psychological return-to-sport criteria. Level III.