Analysis of flip angle (fa) toward image anatomical information in sagital t2* w merge: (study of knee joint magnetic resonance imaging in anterior cruciate ligament tear case)

Abstract

The sagital T2* W MERGE sequence is a sequence in Magnetic Resonance Imaging (MRI) examination of the knee joint in the radiology department of Panti Rapih Hospital Yogyakarta. The value of Flip Angle (FA) on the T2 * W MERGE sequence will affect to anatomical information. The right FA can produce good image contrast of fluid and tissue. This study aims to find out the relationship between FA variations toward anatomical information and to determine the the optimum FA. Ten patients with Anterior Cruciate Ligament (ACL) Tear were scaned by 1.5 Tesla MRI using Sagittal T2 * W MERGE with five flip angle variations: 150, 200, 250, 300, and 350. The anatomical informations were assesed by two qualified radiologists in ACL Tear, Posterior Cruciate Ligament (PCL), Quadriceps Tendon, Joint Effusion, and Hoffa Fat Pad. Data were analyzed by Cross Tabulation, Spearman Rank test and Freadman test. Result showed that there was a significant correlation (p-value < 0,05) between flip angle value to anatomical information (correlation value was -0.55), increasing the FA will reduce the clarity of the anatomical image. Based on Freadman test results, the highest mean rank of image information was 3.89 obtained by FA 200.