Nuclear magnetic resonance imaging of the orbit.

SUMMARY Nuclear magnetic resonance is a noninvasive imaging technique which does not employ ionising radiations. The authors report its application to imaging and tissue characterisation in the normal orbit. The application of x-ray computed tomography (CT) to the investigation of orbital disease has radically changed the diagnostic approach to patients thought to have retrobulbar masses. ' Previously available investigative techniques were either relatively unin-formative (plain films, phlebography) or potentially hazardous (orbitography).2 Applications of ultra-sound have also developed, but the technique has shortcomings, particularly in disease at the apex of the orbit and in its walls.3 X-ray CT also has shortcomings in the orbit: it is relatively nonspecific as regards histology, which is usually inferred from other data. ' It is expensive to install, and sophisticated studies with modem scanners involve substantial radiation to the eye, which cannot be avoided by screening. The radiation dose, while lower than that of comparable techniques, is still considerable,4 and recent studies indicate that, with repeated examinations a cataractogenic dose is easily reached.' Nuclear magnetic resonance (NMR) imaging uses no ionising radiation and is very sensitive to tissue differences. At present relatively few centres have the requisite apparatus, but it seems probable that within a few years it will become a major part of the imaging armamentarium. This paper reports preliminary experience of orbital imaging with NMR after a brief explanation of the principles ofNMR imaging. More complete reviews of NMR are available for the interested reader. 8 Principles ofNMR imaging Nuclei such as that of hydrogen which have an odd number of protons or neutrons tend when placed in a strong magnetic field to become aligned with tha

Ethical problems in radiology: radiological consumerism

One of the causes of the increasing request for radiological examinations occurring in all economically developed countries is the active role played by the patient-consumer. Consumerism places the radiologist in an ethical dilemma, between the principle of autonomy on the one hand and the ethical principles of beneficence, nonmaleficence and justice on the other. The choice made by radiologists in moral dilemmas is inspired by an adherence to moral principles, which in Italy and elsewhere refer to the Judaeo-Christian tradition or to neo-Darwinian relativism. Whatever the choice, the radiologist is bound to adhere to that choice and to provide the patient with all the relevant information regarding his or her state of health

Dural ectasia in adolescent idiopathic scoliosis: quantitative assessment on magnetic resonance imaging

To our knowledge, the assessment of dural sac diameters in patients with adolescent idiopathic scoliosis (AIS) is not reported in the literature. The aim of this study was to find out if, dural ectasia occurs more frequently among patients with AIS, to define cut-off values for dural sac ratio and test the validity of such values. A total of 126 spine MRIs (79 patients with AIS and 47 control subjects) were included in this retrospective analysis (age range 7–25 years, 62% were females). Dural sac diameter (DSD) and vertebral body diameter (VBD) were estimated and dural sac ratio (DSR = DSD/VBD) was calculated at T5 and L3. DSR at T5 and L3 were 0.69 ± 0.12, and 0.52 ± 0.10, respectively, in patients with AIS compared with 0.62 ± 0.11, and 0.44 ± 0.07, respectively, in controls (P = 0.001 at T5 and <0.001 at L3). Our estimated cut-off values for DSR were 0.84 and 0.58 at T5 and L3, respectively. This resulted in 100% sensitivity compared with 74% when using the cut-off values proposed by Oosterhof et al. No statistically significant association was found between the occurrence of dural sac enlargement in patients with AIS and the severity of scoliotic deformity, the apical vertebral rotation, epidural fat thickness, occurrence of pain, neurological deficit, atypical scoliosis or rapid curve progression. Females were affected more frequently than males. As dural sac enlargement means thinning of the pedicles, we believe that the findings of this study have important clinical implications on the preoperative workup of AIS