Electron attachment to molecules in a cluster environment.

Low-energy dissociative electron attachment (DEA) to the CF(2)Cl(2) and CF(3)Cl molecules in a water cluster environment is investigated theoretically. Calculations are performed for the water trimer and water hexamer. It is shown that the DEA cross section is strongly enhanced when the attaching molecule is embedded in a water cluster, and that this cross section grows as the number of water molecules in the cluster increases. This growth is explained by a trapping effect that is due to multiple scattering by water molecules while the electron is trapped in the cluster environment. The trapping increases the resonance lifetime and the negative ion survival probability. This confirms qualitatively existing experiments on electron attachment to the CF(2)Cl(2) molecule placed on the surface of H(2)O ice. The DEA cross sections are shown to be very sensitive to the position of the attaching molecule within the cluster and the orientation of the electron beam relative to the cluster.

[Vertebral fractures: radiological diagnosis, differential diagnosis and prognostic implications]. / Fratture vertebrali: diagnosi radiologica, diagnosi differenziale e implicazioni prognostiche.

Vertebral fractures are a relevant problem for the heavy clinical implications and carrying disability. Vertebral fractures can be traumatic or pathologic, the latter can be benign or malignant, both mostly frequent in the elderly. An initial approach to this issue can use plain radiographs, but the correct extension and evaluation must involve CT and MR imaging. In particular MR is a useful tool for the prognostic evaluation of spine marrow injuries and the differential diagnosis of osteoporotic and metastatic fractures.

[Imaging of acute brain inflammatory disease]. / Imaging della patologia infiammatoria acuta dell'encefalo.

The central nervous system inflammatory disease can be due to any kind of infective agent (bacterial viral, fungal and parasitic), but entails also multiple sclerosis, a primary demyelinating disease in which the causal agent is unknown. MR imaging is, in most often, the procedure of choice, due to her multiplanar and multiparametric imaging, and to her better contrast resolution. The post-contrast imaging with double dose of gadolinium and late sequences enable visualisation of smallest pathologic foci or slightest blood-brain barrier alterations, with a sensibility very higher than post-contrast CT scan. In addition, RM provide to many functional informations, by means of diffusion, perfusion and spectroscopy studies, Bold technique for cortical activation studies and Fiber Tracking technique, in order to demonstrate pathologic modification earlier than they are evident on morphologic imaging. Functional imaging is also employed to monitor response to treatment and damage reversibility.

[Can triphasic spiral CT provide data for the histologic characterization of liver masses?]. / Può la TAC spirale trifasica fornire elementi per la caratterizzazione istologica delle masse epatiche?

Spiral Computed Tomography (CT) has rapidly gained acceptance as the preferred CT technique for routine liver evaluation because it provides image acquisition at peak enhancement of the liver parenchyma during single breath hold. In this study, we evaluated a wide range of non cystic liver lesions with triphasic spiral CT technique, that allows imaging of the entire liver in arterial, portal and equilibrium phases. In particularly we focused on hemangioma, adenoma, focal nodular hyperplasia, hepatocarcinoma and metastases.

[Role of magnetic resonance in shoulder disease]. / Ruolo della risonanza magnetica nella patologia della spalla.

Next to the knee, the shoulder is the most common joint to be referred for MRI. Excellent soft tissue contrast and multiplanar acquisition provide optimal assessment of muscle, tendons, hyaline and fibrous cartilage, joint capsule, fat, bursae and bone marrow. In this article the most common indications for shoulder MRI are reviewed and discussed, but we focused primarily on the rotator cuff syndrome and shoulder instability. Correct diagnosis requires the use of appropriate pulse sequences and imaging planes, proper patient positioning, and a satisfactory surface coil. Moreover, technical improvements continuously augment the ability of MRI to study the shoulder; for example Magnetic Resonance arthrography is superior to the other imaging techniques in evaluation of glenohumeral joint. This interdependence between technical development in MRI and clinical advance in shoulder therapy ensures that MRI will continue to play an important role in the routine management of patients with shoulder disease.

MRI of the small-bowel: how to differentiate primary neoplasms and mimickers.

MRI of the gastrointestinal tract is gaining clinical acceptance and is increasingly used to evaluate patients with suspected small-bowel diseases. MRI may be performed with enterography or enteroclysis, both of which combine the advantages of cross-sectional imaging with those of conventional enteroclysis. In this paper, MRI features of primary small-bowel neoplasms, the most important signs for differential diagnosis and the diseases that can be considered as mimickers of small-bowel neoplasms, are discussed.