No abstract

Helical CT with either a 1.0 or a 1.5 pitch offers the ability to obtain higher quality 3D reconstructions than from comparable conventional CT scans.

Computed x ray tomography (CT) studies of40 patients with proptosis or periorbital swelling, in whom biopsy showed lymphoma in 23 and reactive lymphoid hyperplasia in 17, were analysed in an attempt to identify radiological differences between the two conditions. The results indicate that homogeneity of an orbital mass is a sensitive but non-specific indication of lymphoma, 75% of lymphomatous masses and only 23% of reactive lesions being homogeneous. Bone destruction was seen only in cases of lymphoma, but was rare. Other radiological features of the mass or the affected orbital structures did not allow discrimination of tumour from a reactive lesion.

We describe two patients with neurofibromatosis, each of whom was found to have an arteriovenous malformation (AVM), an uncommon manifestation of the disease, presenting as an extradural space-occupying lesion in the cervical spine. In one patient the finding of an unsuspected AVM at operation led to massive blood loss; in the other magnetic resonance imaging (MRI) of the neck allowed the diagnosis to be made and the hazard of an operation to be avoided. Solid tumours that may occur in the disease of neurofibromatosis are known to cause neurological deficits as the result of space occupation. We wish to draw attention to another pathological entity which may cause neurological deficits: that of AVMs. We also propose that in the investigation of such a patient MRI be borne in mind as a non-invasive radiological tool, particularly as, hopefully, its cost reduces and its availability becomes more widespread.

For detailed musculoskeletal 3D and MPR work, helical CT may not adequately compare with conventional CT and offers no discernible advantage, particularly for pitches of > 1.0.