The purpose of this multicenter study was to determine the accuracy and clinical value of a dedicated breast biopsy system which allows for MR-guided vacuum biopsy (VB) of contrast-enhancing lesions. In five European centers, MR-guided 11-gauge VB was performed on 341 lesions. In 7 cases VB was unsuccessful. This was immediately realized on postinterventional images or direct follow-up combined with histopathology-imaging correlation; thus, a false-negative diagnosis was avoided. Histology of 334 successful biopsies yielded 84 (25%) malignancies, 17 (5%) atypical ductal hyperplasias, and 233 (70%) benign entities. Verification of malignant or borderline lesions included reexcision of the biopsy cavity. Benign histologic biopsy results were verified by retrospective correlation with the pre- and postinterventional MRI and by subsequent follow-up. Our results indicate that MR-guided VB, in combination with the dedicated biopsy coil, offers the possibility to accurately diagnose even very small lesions that can only be visualized or localized by MRI.

ABSTRACT. At our academic institution, we have noticed repeated examples of both false-positive and false-negative MR diagnoses in breast cancer. The most common diagnostic errors in interpreting MRI of the breast are discussed in this review and experience-based advice is provided to avoid similar mistakes. The most common reasons for false-positive diagnoses are misinterpretation of artefacts, confusion between normal enhancing structures and tumours and, above all, insufficient use of the American College of Radiology breast imaging reporting and data system lexicon, whereas false-negative diagnoses are made as a result of missed tiny enhancement, a background-enhancing breast, or enhancement interpreted as benign rather than malignant.

Our purpose was to report about technical success, problems and solutions, as experienced in a first multicentre study on MR-guided localisation or vacuum biopsy of breast lesions. The study was carried out at four European sites using a dedicated prototype breast biopsy device. Experiences with 49 scheduled localisation procedures and 188 vacuum biopsies are reported. Apart from 35 dropped indications, one localisation procedure and 9 vacuum biopsies were not possible (3 times space problems due to obesity, 2 times too strong compression, 3 times impaired access from medially, 2 times impaired access due to a metal bar). Problems due to too strong compression were recognised by repeat MR without compression. During the procedure problems leading to an uncertain result occurred in eight vacuum biopsies, two related to the procedure: one limited access, and one strong post-biopsy enhancement. Improvements after phase-I study concerned removal of the metal bar, development of an improved medial access, of a profile imitating the biopsy gun, optimisation of compression plates and improved software support. The partners agreed that the improvements answered all important technical problems.

A theoretical study of the catalyzed carbonylation process on the model system CH 3 -Ni(CO) 2 Cl reacting with a CO molecule has been carried out using a DFT approach. It has been found that two different reaction channels lead to the carbonylation products (acyl complexes). Along one reaction channel the carbonyl insertion takes place on five-coordinated nickel complexes, while the other reaction channel only involves the formation of fourcoordinated complexes. The two reaction pathways require the overcoming of similar energy barriers for the insertion process (the barriers for the rate-determining step are 4.36 and 6.83 kcal mol -1 in the two cases, respectively). Even if for the model system considered here one reaction channel is slightly more convenient than the other, the computational results suggest that for the real system the two reaction paths can become highly competitive and their relative importance can change depending on the experimental conditions.

The demonstration of bilaterally enlarged ovaries with multiple small cysts at ultrasound is the morphological hallmark of polycystic ovarian syndrome (PCOS). However, a number of patients with clinical and biochemical diagnosis of PCOS have ovaries that are without sonographically visible discrete cysts. A better contrast resolution is obtained with magnetic resonance imaging (MRI) and enables visualization of organ structure not seen with other techniques. The purpose of the study was to relate the clinical and biochemical features of 10 patients presenting with a PCOS profile to magnetic resonance imaging and to compare these findings with those observed at ultrasound. With MRI, at least one ovary typical of PCOS could be visualized in eight patients, while this was the case in only three patients with ultrasound. The ultrasound examinations were indeed equivocal in the majority of patients (seven cases). No apparent relationship could be found between the clinical and biochemical parameters and ovarian morphology assessed by MRI or ultrasound. In summary, the present study supports the superiority of MRI technique to assess ovarian morphology over the ultrasound technology used in our study. However, the recent technological advances in ultrasound, and specifically the advent of high frequency transvaginal sonography, will be of particular interest in the study of PCOS.