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Signal Intensity on MRI of Basal Ganglia in Multiple Sclerosis

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Signal Intensity on MRI of Basal Ganglia in Multiple Sclerosis 30606ournal ofNeurology, Neurosurgery, and Psychiatry 1995;59:306-308 J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.59.3.306 on 1 September 1995. Downloaded from SHORT REPORT Signal intensity on MRI of basal ganglia In multiple sclerosis J Grimaud, J Millar, J W Thorpe, I F Moseley, W I McDonald, D H Miller Abstract gressive, two primary progressive) and 42 age It has been reported that a relative and sex matched controls: healthy subjects reduction in signal intensity on T2 and patients undergoing inve§tigation for weighted ART may be seen in the basal headache, vertigo, or middle ear disorders in ganglia ofpatients with multiple sclerosis whom multiple sclerosis was excluded clini- and furthermore that this is due to cally. These two groups were defined as fol- excessive iron deposition. The basal gan- lows: sex ratio (M/F) in patients with glia are, however, rarely involved clini- multiple sclerosis 0 77 and controls 0-68, cally or pathologically in multiple mean (SD, range) age of patients with multi- sclerosis, casting some doubt on this ple sclerosis 39 9 (11 1, 19-64) years and finding. Therefore MRI was carried out controls 43-3 (11 8 , 24-72) years. Brain in 46 patients with definite multiple scle- MRI was performed with a 1 5T imager. rosis and 42 age matched controls. Contiguous 5 mm thick interleaved axial dual Contiguous, 5 mm thick axial dual echo echo spin-echo images were obtained with spin-echo images of the brain were repetition times (TR) of 2000 or 2700 ms, obtained on a 1-5T imager. Visual rating echo times (TEs) of 32 and 80 ms, and one scales were used to measure the lesion excitation. The field of view was 24 cm, the load as well as the signal intensity of the matrix 192 x 256. globus pallidus, putamen, caudate Signal characteristics of the basal ganglia nucleus, substantia nigra, red nucleus, on long TE images were first analysed in sev- and thalamus. There was a mild degree eral regions: caudate nucleus, putamen, of low signal intensity in the patient globus pallidus, dentate and red nuclei, sub- group in the thalamus only. The signal stantia nigra, and thalamus. Signal change intensity of the thalamus and putamen within the basal ganglia was rated according was never lower than that of the globus to the method proposed by Drayer et al,2 pallidus. Low signal in the basal ganglia which involves comparing the signal charac- http://jnnp.bmj.com/ is rarely, if ever, found in multiple scle- teristics of the basal ganglia relative to the rosis and is not a useful radiological sign. globus pallidus. Three different patterns are described. (3 Neurol Neurolosurg Psychiatry 1995;59:306-308) Normal-decreased signal intensity in the globus pallidus, more prominent than in the putamen and much more prominent than in Keywords: multiple sclerosis; magnetic resonance the thalamus. imaging; basal ganglia; iron Equivocal-decreased signal intensity in the on September 24, 2021 by guest. Protected copyright. globus pallidus, slightly more prominent than Increased deposition of iron in the brain has in the putamen and more prominent than in been found adjacent to chronic multiple scle- the thalamus. rosis plaques.' It has been reported that a rel- Abnormal-decreased signal intensity in the ative reduction in signal intensity on T2 globus pallidus equal to or less prominent NMR Research Unit, MRI may seen in than that in the and caudate and Institute of Neurology, weighted be the basal gan- putamen Queen Square, glia of patients with multiple sclerosis and only minimally more prominent or equally London WC1N 3BG, this has also been attributed to excessive iron prominent to that in the thalamus. UK deposition.2 The low frequency of To assess the visual perception of the J Grimaud pathologi- or of basal as J Millar cal, MRI, clinical3 involvement of the basal degree ganglia hypointensity an JW Thorpe ganglia in multiple sclerosis casts doubt on absolute rather than one nucleus relative to IF Moseley the validity of this finding. We have therefore another a different method was also used. WI McDonald DH Miller studied basal ganglia signal intensity in Each of the basal ganglia was scored sepa- on an scale with Correspondence to: Dr DH patients with multiple sclerosis and controls. rately arbitrary cortical grey Miller, NMR Research matter as the internal reference (0 = isoin- Unit, Institute of Neurology, Queen Square, London tense, 3 = maximum low signal intensity). WC1N 3BG, UK. Method The size and number of white matter Received 1 February 1995 We studied 46 patients with definite multiple lesions were subsequently scored, with both and in revised form 23 May 1995 sclerosis according to the Poser criteria4 (29 short and long TE images. All discrete white Accepted 1 June 1995 relapsing and remitting, 15 secondary pro- matter lesions were registered and weighted Signal intensity on MRI ofbasal ganglia in multiple sclerosis 307 J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.59.3.306 on 1 September 1995. Downloaded from according to their largest diameter. Confluent A subtle decrease in signal intensity rating periventricular lesions, however, were was found in the thalamic nuclei of the weighted according to their smallest diame- patients with multiple sclerosis (mean (SD, ter. This allowed the computation of a semi- median) 0-56 (0-54, 1) compared with the quantitative lesion score as follows: lesion controls 0X12 (0-33, 0; P < 0-001). For the smaller than 5 mm in diameter = 1, lesions other basal ganglia and in particular the puta- 5-10 mm = 2, larger than 10 mm = 3, and men, there was no difference between confluence added an extra point to the score. patients with multiple sclerosis and controls. We scored a lesion on every slice that it Decreased signal intensity in the basal ganglia appeared. Patients were separated into four did not correlate with age or duration of dis- groups on the basis of the degree of MRI ease. Similarly, there was no linear correla- abnormality: normal, mild (1 < lesion load tion between the lesion load in the white < 50), moderate (50 < lesion load < 100), matter and the signal intensity of any of the severe (lesion load > 100). basal ganglia. Greatly reduced signal intensity The relation between the number and in the putamen or caudate relative to the severity (normal, mild, moderate, severe) of globus pallidus as found by Drayer et al 2 was white matter lesions and basal ganglia signal not found in any of our patients. intensity ratings (0, 1, 2, or 3) on dual echo spin echo images were evaluated with Spearman's rank correlation. The non-para- Discussion metric Mann-Whitney test was used to com- With the advent of high field strength imag- pare multiple sclerosis and control groups ing, with long repetition and echo times (T2 with respect to the distribution of signal weighted), a close correlation has been found intensity in the basal ganglia. between areas of prominent low intensity in the extrapyramidal system and the known sites of preferential accumulation of ferric Results iron as documented by Perl's stain and other Among the 42 control subjects there were no necropsy studies.' 5 These findings led to the abnormalities in 24 and patchy white matter hypothesis that the low signal intensities lesions in 18 (lesion load: mean (SD, range, (indicating a short T2 relaxation time) were a median) 7-6 (9-0, 1-32, 4). Those without direct paramagnetic effect of the high iron abnormal white matter were significantly concentration, although the exact relation younger than those with (40-1 (10-5) v 47-4 between T2 values and iron concentration (12-2); P = 0 05) and lesion load correlated remains somewhat controversial.8-" positively with increasing age (r = 0-38; Several independent investigators have P = 0 02). Scans of all patients with multiple suggested that abnormal patterns of iron in sclerosis showed white matter lesions (lesion the brain, shown either postmortem or load: mean (SD, range, median) 100.9 inferred from areas of low signal intensity on (106-6, 5-696, 78). The mean (SD) lesion long TR, long TE MRI are a feature of sev- load in relapsing remitting patients with mul- eral neurological disorders including tiple sclerosis was 100 0 (139.0) compared Huntington's chorea, Parkinson's disease, with 107-5 (54 3) in patients with secondary and multisystem atrophy. A consistent progressive multiple sclerosis (NS). There decrease in signal intensity on images depen- http://jnnp.bmj.com/ was no association between lesion load, dent on T2 in the globus pallidus, substantia patient age, or duration of the disease. nigra, red nucleus, dentate nucleus, and to a With our signal intensity rating scale, the lesser extent, the thalamus, putamen, and mean basal ganglia low signal intensity in caudate, is, however, a striking feature of high controls varied between 0-00 (for the caudate field strength MRI even in healthy adults." nucleus) and 1-79 (for the globus pallidus). The normally lower signal intensity in the The thalamic, putaminal, and caudate nuclei globus pallidus than in the putamen"2 was had intensities similar to the cortex confirmed in the present study (P < 0 0001). on September 24, 2021 by guest. Protected copyright. (median = 0). The globus pallidus and sub- Interestingly, the results of independent stantia nigra had the lowest intensities com- quantitative studies that showed a preferential pared with the cortex (median = 2). The red accumulation of non-haem iron in several nuclei and the dentate nuclei were of inter- basal ganglia, are congruent with our mediate intensity (median = 1; table). qualitative assessment of signal intensity.
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