The high incidence and bioethics of findings on magnetic resonance brain imaging of normal volunteers for neuroscience research.

BACKGROUND: We were finding volunteers for functional magnetic resonance imaging studies with abnormalities requiring referral surprisingly frequently. The bioethics surrounding the incidental findings are not straightforward and every imaging institution will encounter this situation in their normal volunteers. Yet the implications for the individuals involved may be profound. Should all participants have review of their imaging by an expert and who should be informed? METHODS: The normal volunteers that were imaged with magnetic resonance (MR) which were reviewed by a consultant neuroradiologist. All participants completed a volunteer consent form in addition to a standard departmental MR safety screening form. The volunteer screening form requires the general practitioner details to be completed and asks the participant to consider closely the possibility and implications of finding an unexpected but potentially serious abnormality before signing. RESULTS: 525 different individuals were scanned as normal volunteers, the mean age was 35-years and 330 were males. Of these 525, 46 had definite significant abnormalities (8.8%), mean age 50-years. CONCLUSION: We have found a high rate of incidental abnormalities amongst individuals participating in imaging studies at our institution. It is our current practice to inform the research study participant of the findings, counsel them and inform their primary care physician. We think that it is advisable for researchers utilising MR imaging of the brain to have access to trained neuroradiologists, a protocol in place to deal with this problem and take consent in a way that allows the participant to realise the possibility of an abnormal finding.

Proton spectroscopy and imaging at 3T in ataxia-telangiectasia.

BACKGROUND AND PURPOSE: Ataxia-telangiectasia (A-T) is an autosomal recessive disorder with characteristic neurodegeneration of the cerebellum. We used MR spectroscopy to test the hypothesis that cerebellar metabolism in A-T patients would be abnormal relative to healthy controls. METHODS: Twelve adults with A-T and 12 healthy control subjects underwent MR imaging and long-echo time (1)H-MR spectroscopy at 3T. Voxels were acquired in the region of the dentate nucleus of the cerebellum and in parietooccipital white matter, and ratios for N-acetylaspartate (NAA), choline (Cho), and creatine (Cr) were calculated. RESULTS: All of the A-T patients showed marked cerebellar atrophy of the vermis and hemispheres. Two patients showed multiple small foci of hypointensity on T2*-weighted images throughout their brain suggestive of capillary telangiectasia. A further 2 patients had single low-signal-intensity foci. One patient had a tumor, thought to be meningioma radiologically, that was not suspected clinically. No group differences were found in the cerebral spectra, but analysis of the cerebellum revealed significantly lower NAA/Cho and higher Cho/Cr ratios in the A-T patients compared with the controls. There was no difference between groups for the NAA/Cr ratio. CONCLUSION: The findings suggest increased Cho signal intensity in the cerebellum of adult A-T patients. If this finding is shown through the course of the disease, it may assist in the differentiation of early A-T from other forms of ataxia and provide a marker for monitoring treatment efficacy.

MR imaging of patients with localisation-related seizures: initial experience at 3.0T and relevance to the NICE guidelines.

The purpose of this study is to describe our initial experience of imaging adults with localisation-related epilepsy using MR imaging at 3.0T. We discuss the findings in the context of the recently released NICE guidelines that provide detailed advice on imaging people with epilepsy in the UK. 120 consecutive people over the age of 16 years with localisation-related epilepsy were referred for clinical MR examinations from a regional neuroscience centre in England. None of the people had had MR examinations prior to the present study. High resolution MR imaging was performed taking advantage of the high field strength and high performance gradients of the system. Two experienced neuroradiologists reported on the examinations independently and the presence and type of pathology was recorded. There was complete agreement between the two reporters in all 120 cases. The overall frequency of abnormalities shown by MR was 31/120 (26%) and the commonest abnormality shown was mesial temporal sclerosis found in 10/120 (8%). Tumours were shown in 4/120, all of which appeared low grade as judged by imaging criteria. Epilepsy is the commonest neurological condition and demands a significant resource in order to provide good care for sufferers. Recent guidelines published in the UK have suggested that the majority of people with epilepsy should receive brain MR as part of their routine assessment. Our work shows that using the most sophisticated MR imaging in a highly selected population there is a modest pick-up rate of brain abnormalities. If a widespread epilepsy-imaging programme is started the detection rate is likely to be much lower. Although MR is acknowledged to be a reliable way of detecting pathology in people with epilepsy there is a dearth of information studying the health economics of imaging epilepsy in relation to patient management and outcomes.

Magnetic resonance urography in patients with neurogenic bladder dysfunction and spinal dysraphism.

OBJECTIVE: To investigate the reliability of magnetic resonance urography (MRU) using heavily T2-weighted very fast spin-echo sequences in imaging the upper urinary tract in patients with spinal dysraphism and neuropathic bladder dysfunction. PATIENTS AND METHODS: Patients with neuropathic bladder dysfunction secondary to spinal dysraphism may have gross spinal deformity, which makes assessing the urinary tract extremely difficult by ultrasonography or intravenous urography. The study included 50 patients (median age 33 years, range 19-52) with a median (range) Cobb's angle of 60 (0-240) degrees. No contrast medium was given but all patients received 20 mg of intramuscular frusemide 20-30 min before MRU. RESULTS: Thirty-five patients had previous ultrasonography, during which only 42 kidneys and no ureters were visible. Of the 94 renal tracts, MRU visualized all kidneys and 86 (89%) ureters. There was good agreement amongst observers on assessing the kidneys and pelvicalyceal systems (kappa > or = 0.61) but only moderate agreement on evaluating the ureters (kappa < or = 0.61). There was disagreement on normality vs renal parenchymal scarring in 14 (15%) kidneys, about no dilatation vs dilatation of the pelvicalyceal system in 14 (15%) systems and about no dilatation vs dilatation of the ureter in 20 (22%) ureters. The overall quality of the MRU images was rated highly, with a mean (range) score of 4.6 (3-5). CONCLUSION: MRU provides a reliable noninvasive technique for imaging the upper tract in patients who were previously difficult to investigate.

Design and initial evaluation of a low-cost 3-Tesla research system for combined optical and functional MR imaging with interventional capability.

A 3-Tesla research system has been developed for functional and interventional magnetic resonance imaging (MRI) procedures on animal models based on a low field niche spectrometer. Use of two stages of fourth harmonic frequency multiplication has allowed us to produce a high-frequency spectrometer with good frequency stability based on a low-frequency direct digital synthesizer. The system has been designed with the ability to introduce interventional tools such as biopsy needles, radiofrequency (RF) electrodes, and fiber optics for optical spectroscopy and thermal ablation as well as drug infusions to allow function to be studied in the presence of external challenges. Full MR-compatible physiologic support capability allows animals to be maintained in a stable condition over extended periods of study. Functional MR images have been acquired by using gradient echoes (TR/TE = 40/12 msec) from the rat whisker barrel cortex using electrical stimulation (5-V, 1.5-mA, 1-msec pulses at 5 Hz via two needle electrodes inserted into the rat whisker pad). Initial results using respiratory gas challenges of 100% N(2), 100% O(2), and 10% CO(2) have shown excellent agreement between single wavelength (633 nm) optical and functional MR time series with subsecond time resolution. The 1-mm copper electrodes for interventional radiofrequency ablation procedures were easily visualized in the superior colliculus by using gradient echo sequences. This novel, low-cost, high field system appears to be a useful research tool for functional and interventional studies of rat brain and allows concurrent optical spectroscopy. J. Magn. Reson. Imaging 2001;13:87-92.