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A new scintigraphic (nuclear medicine) method to show the accumulation of the extra fatty tissue, glucocerebroside, stored in the bone marrow was described at the Italian Conference in April 1996 by Dr Giuliano Mariani of the Nuclear Medicine Service, University of Genoa.
'The main problem in the long-term follow-up of Gauchers disease has been the identification and assessment of the extent of bone marrow and skeletal involvement,' explained Dr Mariani. 'A reliable method to quantify this would be useful to determine when enzyme replacement therapy should start plus its long-term monitoring.'
Dr Mariani reviewed various nuclear medicine procedures which can be employed to identify the presence and extent of Gauchers deposits in the bone marrow, including a radioactive gas xenon-133 which has been used to evaluate the extent of bone marrow infiltration at a few specialised centres in the USA. 'However this is unlikely to be suitable for routine evaluation in most centres,' he said.
'A recent finding using a radiopharmaceutical agent called99mTc-MIBI has proved to be very promising for the identification of Gauchers disease within the bone marrow. This agent dissolves rapidly in fat in the same way that was intended for xenon-133.
'In fact we explored 99mTc-MIBI partly because it has similar properties to xenon-133; moreover we knew that 99mTc-MIBI accumulates at sites of increased cellularity and enhanced metabolic activity; these two events do occur at the site of bone marrow lipid infiltration in Gauchers disease.
'However, 99mTc-MIBI is widely available and gives a scan signal that is very simple to identify using conventional cameras used in most hospital scanning facilities.
'The agent was intravenously injected into a patient with Gauchers disease. It was shown to be taken up at several sites where Gauchers tissues were known to occur in the bone marrow and clearly matched the bone changes detected by conventional X-ray. Although the scan was not suitable for identifying Gauchers disease in the body itself such as the liver and spleen, selective uptake by Gauchers tissue within the marrow spaces was very striking.
Twelve Patients Evaluated
'A total of 12 patients have now been evaluated and a close correlation was invariably found between scintigraphic findings and results of other imaging methods (such as MRI) with duration of disease or effectiveness of therapy.
'This could be a simple and sensitive method to evaluate patients and their progress following enzyme replacement therapy,' said Dr Mariani. 'The amount of radiation used in one set of images is less than that used by conventional skeletal X-rays.
'I am interested in setting up a collaborative trial of Gauchers patients so that bone marrow disease can be visualised with confidence during therapeutic monitoring.'
Medical practitioners who would like more details should see the initial paper 'Scintigraphic findings and images in Gauchers disease', reported by G. Mariani, N. Molea, L. La Civita et al in the European Journal of Nuclear Medicine, Vol 23, No 4 April 1996, pp 465-470. .
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Source: Gauchers News September 1996
© Copyright Gauchers Association 1996