New Perspectives and Challenges in Abdominal Imaging with the MAGNETOM Trio, A Tim System
Christoph J. Zech; et al.
University Hospitals-Grosshadern/Ludwig-Maximilians-University, Munich, Germany | 31.05.2007
Fig. A-1 Comparison of a navigator-triggered T2-weighted TSE sequence of the liver on a 3T system (MAGNETOM Trio, Siemens Medical Solutions). The time of acquisition is decreased from 1:52 min without (A) parallel imaging to 1:11 min with (B) parallel imaging with an acceleration factor of 2. Same parameter settings were used for both sequences: TR: > 1900 ms, depending on the respiratory cycle; TE: 109 ms; 27 slices with 6 mm thickness; (384)² matrix with a rectangular field of view (360x270 mm²).
Fig. A-2 Transversal (A) and coronal (B) VIBE fat-sat T1-weighted 3D GRE images acquired on a 3T system (MAGNETOM Trio, Siemens Medical Solutions) with a novel whole-body coil concept (total imaging matrix) and parallel imaging with an acceleration factor of 2 for the transversal study and 3 for the coronal study. Note the excellent image homogeneity and fat suppression. The whole liver can be covered with 2 mm slices within a single breath-hold of 18 s.
Fig. B Comparison of a navigator-triggered T2-weighted TSE sequence of the liver on a 3T system using the hyper-echo technique (MAGNETOM Trio, Siemens Medical Solutions). Each two sections at different levels with a flip angle of 60° (A) and 120° (B). The other parameter settings were the same for both sequences: TR: > 1900 ms, depending on the respiratory cycle; TE: 109 ms; 27 slices with 6 mm thickness; (384)² matrix with a rectangular field of view (360 x 270 mm²).
Fig. C-1 Female patient with fibromuscular dysplasia. MR angiography on MAGNETOM Trio with submillimeter spatial resolution (0.8 x 0.8 x 0.8 mm³) clearly demonstrating the string-of-beads appearance of the FMD lesions. The sequence can be acquired in 18 s with help of parallel imaging (GRAPPA; acceleration factor 3).
Fig. C-2 Timeresolved MR angiography on a 3T system (MAGNETOM Trio) with a novel whole-body coil concept (total imaging matrix). At a voxel size of 2 x 2 x 2 mm³, one 3D data set is acquired every 2 susing parallel imaging (GRAPPA; acceleration factor 2).
Fig. D T1-weighted FLASH 2D sequence on a MAGNETOM Trio, 120 s after injection of Gadolinium in a 54-year-old female patient with polycystic kidney disease. Excellent depiction of the innumerous small cysts, which have to be differentiated from cystic renal cell carcinoma. Although a high spatial resolution is maintained with a (384)² matrix, 23 slices can be acquired in 18 s.
Fig. E T1-weighted FLASH 2D sequence with fat-saturation on a 3T system (MAGNETOM Trio, Siemens Medical Solutions) in a healthy volunteer. The sequence with 5 mm slice thickness and a 320 x 256 matrix shows already a very good visualization of the anatomical area of the pancreatic head. However, on the 3T system a substantial increase in spatial resolution with 3 mm slice thickness and a 384 x 320 matrix is still possible without a visible loss of signal (B). Note the superior visualization of the pancreatic head in (B).
Fig. E Submillimeter (0.9 x 0.9 x 0.9 mm³) T2-weighted 3D TSE sequence with variable flip angle technique on a MAGNETOM Trio in a patient with PSC (Primary Sclerosing Cholangitis), suffering from a severe stenosis at the confluence of the left and right hepatic duct. Due to the high SNR at 3T there is no significant difference of image quality between A (parallel imaging; acceleration factor 2) and B (parallel imaging; acceleration factor 4), although the time of acquisition of the respiratory triggered sequence in free-breathing is decreased from around four (A) to two (B) minutes.
Fig. E T2*-weighted 2D GRE sequence in the liver-specific phase after injection of ferucarbotran (Resovist®, Schering Germany, Berlin) in a 68-year-old female patient after liver transplantation. The examination was able to rule out a focal liver lesion (e.g. a hepatocellular carcinoma) with high confidence due to the excellent signal loss in the normal liver parenchyma after injection of the SPIO-contrast agent and due to the high spatial resolution. Sequence parameters are TR/TE/α 132/7.32/30 with 5 mm slice thickness and a 320 x 256 matrix. The whole liver with 37 slices was covered in 4 x 17 seconds breathhold.