[Methodologic variants on rapid MR imaging of the liver]

The development of rapid imaging methods makes it possible to obtain T1 and T2-weighted MR images in less than 15 seconds. Consequently images can be obtained without respiratory artefacts. An attempt has been made to obtain optimal factors for the fast-field-echo procedure in order to obtain satisfactory images of the liver with T1 and T2 sequences. By moving the examination couch, it is possible to obtain 10 mm transverse sections without gaps throughout the entire liver in a reasonable time. The additional use of contrast medium (Gd-DTPA) provides information about perfusion and leads to an increase in contrast between lesions and normal liver tissue with adequate image quality. The method is particularly valuable before surgery for liver metastases.

[Risks and artifacts in MRT (1.5 tesla) caused by metallic foreign bodies. Studies on phantoms and 60 patients]

Our experience of the effects of metallic foreign bodies on MRT high field examinations is described. In vitro measurements showed moderate magnetic torsion or displacement in a few cases. The findings in 60 patients with various metal foreign bodies and the resulting artifacts are discussed. Despite local loss of information, in the majority of cases there is additional evidence provided by MRT, which suffers less from foreign body artifacts than does CT. Stainless steel implants result in some signal loss and geometric distortion, but do not usually constitute a danger to the patient and do not affect the diagnostic information from surrounding structures.

[Pulse triggering in magnetic resonance tomography in high-field strength]

Gated images of patients with stronger pulsation artefacts in the brain stem were produced on a 1.5 tesla MR-imager, registering blood pulsations by means of a finger plethysmograph. A minimization of movement artefacts was achieved and thus sufficient diagnostic-value of images in these patients was noticeable. This gating method seems to be a promising simple alternative compared to the well known cardiac gating for imaging of the head and neck area. Its advantages and limitations are demonstrated.

[Magnetic resonance tomographic studies at 2.0 Tesla. Evaluation of clinically relevant parameters]

After having used a 2 Tesla prototype whole body scanner for about one and a half years, it is now possible to comment on the clinical value of high field strengths. The methods and techniques employed are described. The problems arising from high field strengths are discussed and their effect on clinical diagnosis is indicated.