Preoperative magnetic resonance and intraoperative ultrasound fusion imaging for real-time neuronavigation in brain tumor surgery.

PURPOSE: Brain shift and tissue deformation during surgery for intracranial lesions are the main actual limitations of neuro-navigation (NN), which currently relies mainly on preoperative imaging. Ultrasound (US), being a real-time imaging modality, is becoming progressively more widespread during neurosurgical procedures, but most neurosurgeons, trained on axial computed tomography (CT) and magnetic resonance imaging (MRI) slices, lack specific US training and have difficulties recognizing anatomic structures with the same confidence as in preoperative imaging. Therefore real-time intraoperative fusion imaging (FI) between preoperative imaging and intraoperative ultrasound (ioUS) for virtual navigation (VN) is highly desirable. We describe our procedure for real-time navigation during surgery for different cerebral lesions. MATERIALS AND METHODS: We performed fusion imaging with virtual navigation for patients undergoing surgery for brain lesion removal using an ultrasound-based real-time neuro-navigation system that fuses intraoperative cerebral ultrasound with preoperative MRI and simultaneously displays an MRI slice coplanar to an ioUS image. RESULTS: 58 patients underwent surgery at our institution for intracranial lesion removal with image guidance using a US system equipped with fusion imaging for neuro-navigation. In all cases the initial (external) registration error obtained by the corresponding anatomical landmark procedure was below 2 mm and the craniotomy was correctly placed. The transdural window gave satisfactory US image quality and the lesion was always detectable and measurable on both axes. Brain shift/deformation correction has been successfully employed in 42 cases to restore the co-registration during surgery. The accuracy of ioUS/MRI fusion/overlapping was confirmed intraoperatively under direct visualization of anatomic landmarks and the error was < 3 mm in all cases (100 %). CONCLUSION: Neuro-navigation using intraoperative US integrated with preoperative MRI is reliable, accurate and user-friendly. Moreover, the adjustments are very helpful in correcting brain shift and tissue distortion. This integrated system allows true real-time feedback during surgery and is less expensive and time-consuming than other intraoperative imaging techniques, offering high precision and orientation.

[Extrinsic allergic alveolitis of occupational origin: apropos of 2 cases]. / Alveolite allergica estrinseca di origine professionale: a proposito di 2 casi.

Extrinsic Allergic Alveolitis (E.A.A.) is an immunological disorder caused by inhalation of various etiological agents (vegetable and animal dusts, fungi, organic simple chemicals) mostly present in work environment. Intensive and prolonged occupational exposure to antigens dimensionally able to reach peripheral airways, where they bring about their immunological effects, allows to consider hypersensitivity pneumonitis as a typical work-related disease. The wide range of pathological findings and evolution of E.A.A. often imply difficulty in diagnosis inspite of availability of diagnostic consolidated criteria. The integrated assessment of history and physical findings, radiological features, pulmonary functions tests, and specific and aspecific immunological data, often allows to make diagnostical conclusion without use of invasive methods (BAL and lung biopsy). In this note we refer two cases of E.A.A. occurred respectively in agricultural and industrial environment, whom etiological and evolutive features suggest an occupational pathogenesis. The first one is a typical "farmer's lung", the second one a hypersensitivity pneumonitis in a cheese washer. The diagnosis was performed by means of historical, clinical, radiological and pulmonary functional outcomes. In the first case specific serum precipitins against M. Faeni were present, in the second one the immunological pathogenesis of the pneumonitis was demonstrated by means of bronchial lavage cytological data and serum IgG dosage. In both cases the removal from specific antigen exposure and the prolonged steroid treatment induced symptomatological regression and complete recovery of functional tests.

[Occupational asthma]. / Asma occupazionale.

Bronchial asthma has been defined as a state of airway obstruction of variable degree correlated casually with exposure to volatile dusts, gases, vapours or fumes in the working environment. In this review we considered the causes of occupational asthma, the diagnosis, the pattern of asthmatic reactions and their mechanism, the predisposing factors, the epidemiology, the prognosis and finally the cure and prevention (review article, 165 references).

[Occupational diseases: considerations on a clinical case series]. / In tema di patologia professionale: considerazioni su una casistica clinica.

The authors examine cases of occupational diseases diagnosed between 1982 and 1988 in patients admitted to "Divisione di Medicina del Lavoro I Sezione di medicina del Lavoro del Dipartimento di Medicina preventiva, occupazionale e di comunità dell'Università di Pavia". The most frequent syndromes concerns the auditory apparatus (having losses or deafness due to noise) and the respiratory system, whereas new safety regulations have given rise to the disappearance of benzene-induced hematologic abnormalities. Most of, the "classical" features of occupational diseases have disappeared, since early diagnosis has permitted the adoption of opportune technical and sanitary measures. The authors emphasize the necessity for role of Occupational Medicine (ever following the sentences 179 and 206 of the "Corte Costituzionale") to be not prevention, but also diagnosis, treatment and rehabilitation; therefore there is a need, all over the country, for adequate structures for the diagnosis and treatment of the occupational diseases.

Carotid occlusive disease: an electrophysiological macular investigation.

Thirteen patients with carotid stenosis were studied by the authors by the measuring the Visual Evoked Potentials (VEPs) before and after thromboendarterectomy. This test of retinal function measures the recovery time of the amplitude of the major positive peak (P100) after photostress. When compared to that we observed in controls, we found, a significant increase of the P100 recovery time in patients suffering from carotid disease with severe stenosis. The method proved suitable for the functional evaluation of the vascular reconstruction of the carotid area, since four weeks after surgery a physiological recovery of the amplitude of VEP was observed. This method is proposed by the authors for the long-term functional evaluation of patients subjected to carotid thromboendarterectomy for tight stenosis of the carotid bifurcation.

VEP pattern after photostress: an index of macular function.

Eighty-seven subjects were examined by means of visual evoked potentials (VEPs) to evaluate the recovery time of the amplitude of the pattern VEP after photostress. Twenty-eight subjects were normal and 59 patients were affected by carotid occlusive disease, vascular retinopathies with and without macular involvement, and connective tissue diseases treated with antimalarial drugs. This examination method emphasizes visual dysfunction in a stage where ophthalmological changes are absent or minimal and therefore may be a useful test for the investigation of macular function.