[New techniques and pulse sequences in MRI of the liver]

The MRI techniques which have contributed to increasing utilization of MRI for abdominal imaging are described and recent advances addressed.

For breath-hold examinations of the abdomen, two basic techniques are required: array coil technology and fast and ultrafast pulse sequences providing T1 and T2 contrast.

Circular polarized array coils render high signal-to-noise ratios (SNR) within large imaging volumes. With fast gradient-echo sequences the liver can be scanned with or without fat saturation within one breath-hold. When adequate parameters are selected, T2-weighted fast (turbo) spin-echo sequences allow high contrast between normal liver tissue and focal liver lesions, even if breath-hold acquisition is applied. Moreover, good soft tissue contrast can also be achieved with ultrafast single-shot sequences. Based on this sequence type, MRCP with a 512 matrix could be performed. The "TRUE FISP" allows for high resolution visualisation of vessels without contrast media. Three-dimensional T1-weighted sequences allow for scanning the upper abdomen with a slice thickness of 3 mm within one breath-hold. Diffusion-weighted sequences contribute to the characterisation of focal liver lesions.

Modern MRI technology including phase-array coils and high-performance gradient systems made it possible to perform all examinations in breath-hold techniques, reducing motion artifacts.