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Liver and pancreas: improved spin-echo T1 contrast by shorter echo time and fat suppression at 1.5 T
D G Mitchell1, S Vinitski, S Saponaro
1Department of Radiology, Thomas Jefferson University Hospital and Jefferson Medical College, Philadelphia, PA 19107.
Abstract:
T1-weighted spin-echo magnetic resonance (MR) images have had limited soft-tissue contrast at 1.5 T. The authors investigated the effects of echo-time (TE) minimization and fat suppression on MR images of the liver and pancreas. Two sets of MR images were obtained with identical repetition times and other parameters. In 10 subjects with seven liver lesions, images with TEs of 20 and 12 msec were compared. In 18 additional subjects with seven liver lesions and five pancreatic carcinomas, images with identical TEs but with and without fat suppression were compared. Contrast-to-noise ratios (CNRs) were greater with a TE of 12 msec than with a TE of 20 msec for liver versus spleen (7.6 vs 4.9, P = .014) and liver versus lesion (6.9 vs 3.9, P = .031). In patients without fatty liver, CNR for six lesions versus liver was greater (9.5 vs 6.0, P = .014) with fat suppression. CNR between glandular pancreas and cancer was most conspicuous with fat suppression, but fat planes were less distinct. Minimization of TE improves T1-weighted images significantly. Fat suppression also improves CNR, but the disadvantages of fat suppression do not allow elimination of conventional T1-weighted images.
Insights
Minimizing echo time (TE) significantly enhances T1-weighted magnetic resonance (MR) images. Fat suppression also improves contrast-to-noise ratios (CNRs), but conventional T1-weighted images remain essential for liver and pancreas imaging.
Area of Science:
- Radiology
- Medical Imaging
- Magnetic Resonance Imaging
Background:
- T1-weighted spin-echo magnetic resonance (MR) imaging at 1.5 Tesla often exhibits limited soft-tissue contrast.
- Optimizing image quality is crucial for accurate diagnosis of liver and pancreatic conditions.
Purpose of the Study:
- To evaluate the impact of echo time (TE) minimization on T1-weighted MR images.
- To assess the effectiveness of fat suppression techniques in improving contrast-to-noise ratios (CNRs) for liver and pancreas imaging.
Main Methods:
- Two sets of MR images were acquired with identical repetition times and parameters.
- TE was minimized (12 msec vs 20 msec) in subjects with liver lesions.
- Fat suppression was applied with identical TEs in subjects with liver lesions and pancreatic carcinomas.
Main Results:
- A shorter TE of 12 msec resulted in significantly greater CNRs for liver versus spleen and liver versus lesion compared to a 20 msec TE.
- Fat suppression improved CNR for liver lesions in patients without fatty liver.
- Fat suppression enhanced the conspicuity of pancreatic cancer but reduced the distinctness of fat planes.
Conclusions:
- Minimizing TE is a significant improvement for T1-weighted MR imaging quality.
- While fat suppression enhances CNR, its limitations mean conventional T1-weighted images are still necessary for comprehensive liver and pancreas assessment.