We report on two patients who underwent magnetic resonance imaging (MRI) as part of the evaluation of focal liver lesions. Both lesions had completely different MRI appearances, showing characteristics of benign and malignant liver lesions. Neither patient had clinical signs of endocrine hyperactivity, and both underwent subsequent liver resection. Histology showed neuroendocrine liver tumors in both patients; and because no primary tumor could be identified after careful search, the diagnosis of primary neureoendocrine tumor of the liver was established. Our observations suggest that primary neuroendocrine tumors of the liver may have a wide spectrum of appearances on MRI.

No abstract

We describe the prenatal MR findings in a 29-week fetus with a cloacal variant (urogenital sinus and anterior placed anus) in combination with an enlarged clitoris and urethral duplication and correlate them with postnatal imaging. Fetal MR imaging permits the diagnosis and characterization of cloacal and urogenital sinus malformations in utero. This information may guide pre-, peri-and postnatal management.

After his girl friend had been diagnosed with active pulmonary tuberculosis, a 45-year old male was referred to rule out transmission of this disease. The chest x-ray showed no signs of tuberculosis, however a small retrosternal lung nodule was found on the lateral film. Three months later, the nodule showed an increase in size and a CT of the chest was performed: No nodule could be found in the expected retrosternal location, but incidentally a small nodule in the right upper lobe was identified. This nodule could retrospectively be identified on the previous chest X-rays, its size had been increasing. After surgical removal, the lesion was diagnosed to be an adenocarcinoma T1, N0, M0. Careful follow-up of small intrapulmonary nodules detected on chest X-rays is highly advisable, especially in smokers of middle and older age bronchial carcinoma and therefore a straight forward approach with excision of the nodule should be considered. Nodules have to be surgically removed if an increase in size can be noted.

In the history of the kinetic theory of fluids, 1969-1970 was a crucial year. In that year Alder and Wainwright [2] published a paper in which they demonstrated the breakdown of the 'Molecular Chaos' assumption. The Molecular Chaos assumption, originally introduced by Boltzmann as the `Stofizahlansatz', states that the collisions experienced by a molecule in a fluid are uncorrelated. One consequence of this assumption is that the velocity autocorrelation function (VACF) of a tagged particle in fluid should decay exponentially. What Alder and Wainwright found is that the VACF of a particle in a moderately dense fluid of hard spheres or hard disks does not decay exponentially but algebraically. These algebraic long-time tails are the consequence of coupling between particle diffusion and shear modes in the fluid.The Alder-Wainwright simulations caused a complete overhaul of the kinetic theory of dense fluids. The subsequent theoretical analyses of algebraic long-time tails were either based on an extension of kinetic theory [3] or on mode-coupling theory [4]. For a review, see ref. [5] . In the mode-coupling theory by Ernst, Hauge and van Leeuwen [4], it is assumed that the long-time tail is the consequence of coupling between particle diffusion and shear modes in the fluid. To a first approximation. the leading term in the long-time tail of the velocity ACF is given by:where p is the number density, Do the 'bare' self-diffusion constant, vo the kinematic viscosity and D the dimensionality.Following this theoretical work, simulations were performed by Levesque and Ashurst [6] and, most extensively, by Erpenbeck and Wood [7,8] with the aim to verify the validity 'This paper is based on material that has either been published elsewhere or has been submitted for publication. Microscopic Simulations of Complex Flows 279Edited by M. Mareschal, Plenum Press, New York, 1990 41.0.