Hermann Requardt

Prototype Breast Coil for Mr-guided Needle Localization

Objective Evaluation of breast lesions detected by MR alone is a problem: Preoperative MR-guided localization is difficult, since the breast is not accessible by a needle within the breast coil. Magnetic resonance-guided core biopsy and needle aspiration are impossible. Together with Siemens Erlangen, a prototype localization breast coil has been developed and tested. Materials and Methods The device consists of a circular polarized coil, which contains two plates for mediolateral breast compression. They are perforated with numerous holes and thus allow access to the breast from both sides. By means of bushings, which fit into the holes, sterile needle insertion in a horizontal path is possible. Results So far, precise needle insertion has been possible in 10 of 11 lesions, allowing exact needle insertion into 5 invasive carcinomas (1 MR-detected), 1 MR-detected additional focus, 2 in situ carcinomas (1 MR-detected), and 3 benign lesions. Conclusion Our studies show that MR-guided needle localization is possible.

Degenerative cartilage lesions of the hip—Magnetic resonance evaluation

The capability of magnetic resonance imaging (MRI) to visualize early degenerative arthritis of the hip was investigated. The study was performed on 8 healthy students and 45 elderly volunteers. Images were obtained by using an electronically variable Helmholtz coil (switched-array coil, SAC). In order to diagnose degenerative lesions of the joint cartilage, FISP sequences with a flip angle of 70 degrees were found preferable to compared sequences. MRI-detectable signs of degenerative arthritis of the hip were narrowed joint space due to partially thinned cartilage layers, focal areas of either increased or decreased signal intensity in the hyaline cartilage, complete loss of cartilage, and signal variation in the bone marrow. MRI of the hip may be appropriate to detect early degenerative changes in the hips of young high-risk patients to facilitate therapy planning.

Nuclear magnetic resonance apparatus having at least two transmission frequencies

For improving the spectral resolution and/or the signal-to-noise ratio of a nuclear magnetic resonance apparatus for examining first types of atomic nuclei that are nuclear-magnetically coupled to second types of atomic nuclei, signals are additionally emitted on the resonant frequency of the second type of atomic nucleus during the examination of the first type of atomic nucleus. To this end, the nuclear magnetic resonance apparatus includes a reception channel and only one transmission channel for both resonant frequencies. The transmission channel contains a respective synthesizer for each resonant frequency, which define the transmission frequency and contains a modulator unit shared in common by both resonant frequencies.

MR imaging of experimental meningeal melanomatosis in nude rats.

MR imaging of the rat brain has become an increasingly frequently used method in experimental neuroradiology. On a generally available 1.5 T whole body tomograph, supplemented with an individually made small coil and a special SE sequence we obtained fairly fine images of the structures of the rat brain. With gadolinium-DTPA, we were able to visualize posterior fossa and cervical leptomeningeal growth of intrathecally injected B16 melanoma in nude rats. Using MRI to follow experimental leptomeningeal metastasis, may provide a new means for diagnostic evaluation and preclinical testing of treatment modalities.