Single- and Bicomponent Analyses of T2<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mrow><mml:mo>⁎</mml:mo></mml:mrow></mml:math>Relaxation in Knee Tendon and Ligament by Using 3D Ultrashort Echo Time Cones (UTE Cones) Magnetic Resonance Imaging

Abstract

The collagen density is not detected in the patellar tendon (PT), posterior cruciate ligament (PCL), and anterior cruciate ligament (ACL) in clinic. We assess the technical feasibility of three-dimension multiecho fat saturated ultrashort echo time cones (3D FS-UTE-Cones) acquisitions for single- and bicomponent T2<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"><mml:mrow><mml:mo>⁎</mml:mo></mml:mrow></mml:math>analysis of bound and free water pools in PT, PCL, and ACL in clinic. The knees of five healthy volunteers and six knee joint samples from cadavers were scanned via 3D multiecho FS-UTE-Cones acquisitions on a clinical scanner. Single-component fitting of T2<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M3"><mml:mrow><mml:msub><mml:mrow><mml:mo>⁎</mml:mo></mml:mrow><mml:mrow><mml:mi mathvariant="normal">M</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>and bicomponent fitting of short T2<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M4"><mml:mrow><mml:mo>⁎</mml:mo></mml:mrow></mml:math>(T2<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M5"><mml:mrow><mml:msub><mml:mrow><mml:mo>⁎</mml:mo></mml:mrow><mml:mrow><mml:mi mathvariant="normal">S</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>), long T2<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M6"><mml:mrow><mml:mo>⁎</mml:mo></mml:mrow></mml:math>(T2<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M7"><mml:mrow><mml:msub><mml:mrow><mml:mo>⁎</mml:mo></mml:mrow><mml:mrow><mml:mi mathvariant="normal">L</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>), short T2<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M8"><mml:mrow><mml:mo>⁎</mml:mo></mml:mrow></mml:math>fraction (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M9"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">F</mml:mi><mml:mi mathvariant="normal">r</mml:mi><mml:mi mathvariant="normal">a</mml:mi><mml:mi mathvariant="normal">c</mml:mi><mml:mo>_</mml:mo></mml:mrow><mml:mrow><mml:mi mathvariant="normal">S</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>), and long T2<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M10"><mml:mrow><mml:mo>⁎</mml:mo></mml:mrow></mml:math>fraction (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M11"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">F</mml:mi><mml:mi mathvariant="normal">r</mml:mi><mml:mi mathvariant="normal">a</mml:mi><mml:mi mathvariant="normal">c</mml:mi><mml:mo>_</mml:mo></mml:mrow><mml:mrow><mml:mi mathvariant="normal">L</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>) were performed within tendons and ligaments. Our results showed that biexponential fitting was superior to single-exponential fitting in PT, PCL, and ACL. For knee joint samples, there was no statistical difference among all data in PT, PCL, and ACL. For volunteers, all parameters of bicomponent fitting were statistically different across PT, PCL, and ACL, except for T2<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M12"><mml:mrow><mml:msub><mml:mrow><mml:mo>⁎</mml:mo></mml:mrow><mml:mrow><mml:mi mathvariant="normal">S</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>, T2<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M13"><mml:mrow><mml:msub><mml:mrow><mml:mo>⁎</mml:mo></mml:mrow><mml:mrow><mml:mi mathvariant="normal">L</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>, and T2<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M14"><mml:mrow><mml:msub><mml:mrow><mml:mo>⁎</mml:mo></mml:mrow><mml:mrow><mml:mi mathvariant="normal">M</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>resulting in flawed measurements due to the magic angle effect. 3D multiecho FS-UTE-Cones acquisition allows high resolution T2<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M15"><mml:mrow><mml:mo>⁎</mml:mo></mml:mrow></mml:math>mapping in PT, PCL, and ACL of keen joint samples and PT and PCL of volunteers. The T2<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M16"><mml:mrow><mml:mo>⁎</mml:mo></mml:mrow></mml:math>values and their fractions can be characterized by bicomponent T2<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M17"><mml:mrow><mml:mo>⁎</mml:mo></mml:mrow></mml:math>analysis that is superior to single-component T2<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M18"><mml:mrow><mml:mo>⁎</mml:mo></mml:mrow></mml:math>analysis, except for ACL of volunteers.