Novel technology: Superb microvascular imaging (SMI) detects
Ultrasound with superb microvascular imaging (SMI) is a novel microvascular imaging technology which may be useful to assess the vascularity of the torn anterior cruciate ligament (ACL) as a potential measure of healing potential following surgery. This study aimed to quantify the vascularity of the torn and intact ACL using ultrasound with SMI.

23 patients who were diagnosed with an ACL tear with an intact contralateral ACL were enrolled (ACL injury group). 10 healthy volunteers who had intact ACLs in both knees were also recruited (ACL healthy controls). The vascularity of the ACL was assessed using SMI within 15 mm from the tibial insertion in both knees. The amount of the vascular signal was assessed using a semi-quantitative grading scale (vascularity grade: grade 0–3) and a quantified ratio of vascularized area with respect to total area of the region of interest (vascularity ratio).

--In the ACL injury group, a significantly higher vascularity grade and ratio were observed in the torn ACL (vascularity grade 0–3: 1, 8, 7, and 7 patients, respectively; vascularity ratio: 1.3?±?1.4%) than the contralateral intact ACL (vascularity grade 0–3: 21, 1, 1, and 0 patients, respectively; vascularity ratio: 0.1?±?0.5%), whereas no significant difference was observed between both ACLs in the ACL healthy control group.

In summary, SMI was helpful for an assessment of enhanced vascularity in injured ACL, which may signify ACL ripening potential or condition after rebuilding or reparation.