Are 3D FSE MRI sequences of the knee at 1.5 T effective in the detection of meniscal and ligament tears? How useful are they?

Radiol Bras. 2016 Mar/Abr;49(2):V–VI The use of fast spin-echo (FSE) magnetic resonance imaging (MRI) sequences is the most versatile way of evaluating the musculoskeletal system. Anisotropic, two-dimensional (2D) sequences have greater resolution in the acquisition plane whereas the voxel resolution in isotropic three-dimensional (3D) volumetric sequences is the same in all planes with no loss of spatial resolution and with no distortion. Initially, 3D gradient-echo sequences which had acceptable acquisition time and high resolution but inadequate tissue contrast were the standard for evaluating the musculoskeletal system. As of 2007, technological advances led to more consistent use of 3D FSE sequences in such evaluations, because 3D FSE sequences provide greater tissue contrast for clinical application in the knee than do 3D gradient-echo sequences. Imaging studies of the knee structures can require the use of oblique planes with special orientation. That is the case of anterior cruciate ligament evaluation, a common situation on the daily practice. In 2007, Rajeswaran et al. highlighted the value of using oblique planes to evaluate the popliteofibular ligament, which plays a role in instability related to lesions of the posterolateral corner structures of the knee. Evaluations of the articular cartilage of the knee can also benefit from the use of 3D isotropic volumetric sequences due to its capacity to reformat in different planes and its greater spatial resolution which improves the characterization of cartilagineous lesions. This last characteristic has a particular application in the femoral trochlea. The articular cartilage evaluation in this area, using axial planes with the usual angulation, has certain limitations. The sagittal plane is called in order to complement this evaluation, although it can be less precise due to partial volume effects. Para-axial slices, perpendicular to the articular surface of the trochlea, can better define injury in this area. Regarding the detection of ligament and meniscal injuries, the performance of volumetric sequences is similar to that of 2D sequences, although the quality of 3D images is considered inferior to that of 2D images. Although some authors question the real value of 3D FSE sequences for the diagnosis of meniscal and cartilaginous lesions in