Rapid 3D‐T_1ρ mapping of the knee joint at 3.0T with parallel imaging

Abstract

Three-dimensional spin-lattice relaxation time in the rotating frame (3D-T 1 ) with parallel imaging at 3.0T was implemented on a whole-body clinical scanner. A 3D gradient-echo sequence with a self-compensating spin-lock pulse cluster was combined with generalized autocalibrating partially parallel acquisitions (GRAPPA) to acquire T 1 -weighted images. 3D-T 1 maps of an agarose phantom and three healthy subjects were constructed using an eight-channel phased-array coil without parallel imaging and with parallel imaging acceleration factors of 2 and 3, in order to assess the reproducibility of the method. The coefficient of variation (CV) of the median T 1 of the agarose phantom was 0.44%, which shows excellent reproducibility. The reproducibility of in vivo 3D-T 1 maps was also investigated in three healthy subjects. The CV of the median T 1 of the patellar cartilage varied between ϳ1.1% and 4.3%. Similarly, the CV varied between ϳ2.1-5.8%, ϳ1.4 -8.7%, and ϳ1.5-4.1% for the biceps femoris and lateral and medial gastrocnemius muscles, respectively. The preliminary results demonstrate that 3D-T 1 maps can be constructed with good reproducibility using parallel imaging. 3D-T 1 with parallel imaging capability is an important clinical tool for reducing both the total acquisition time and RF energy deposition at 3T. Magn Reson Med 56:563-571, 2006.

Assessment of T1, T1ρ, and T2 values of the ulnocarpal disc in healthy subjects at 3 tesla

“…A series of T 1ρ and T 2 -weighted images was acquired with a 3D GRE sequence with T 1ρ or T 2 magnetization preparation, respectively [22][23][24][25]. The imaging parameters were: TR/TE = 80/2.96 ms, flip angle = 20°, field-of-view = 68 × 68 mm 2 , slice thickness = 3 mm, matrix = 96 × 192, nominal voxel size = 0.7 × 0.35 × 3 mm 3 , number of slices = 10, acquisition bandwidth = 260 Hz/pixel, and acquisition time of 2 min.…”

Rapid 3D‐T1 mapping of cartilage with variable flip angle and parallel imaging at 3.0T

“…PROTEOGLYCAN (PG) is the major constituent of articular cartilage, and the loss of PG is an initiating event in the early stages of osteoarthritis (OA) (1)(2)(3)(4). Recent work on delayed gadolinium (Gd)-enhanced MRI of cartilage (dGEMRIC) and sodium MRI have shown that it is possible to measure PG changes in cartilage both in vivo and in vitro (5,6).…”

A Simplified Method of T1ρ Mapping in Clinical Assessment of Knee Joint

“…Moreover, it is stressful to patients to remain motionless in the narrow space of the MR scanner. Use of a parallel imaging technique is an eŠective solution, and its clinical utility for T 1 r mapping has been reported 19,20 ; a novel fast pulse sequence for T 1 r mapping acquisition is also eŠective but remains under investigation. 18,21 Our proposed method is also a solution for shortening MR examination time with preservation of the reliability of the T 1 r relaxation time for the tissue, and it might be eŠec-tive in clinical use.…”