Differential diagnosis of multiple sclerosis: contribution of magnetic resonance techniques

It is widely accepted that magnetic resonance imaging (MRI) findings are not totally specific for the diagnosis of multiple sclerosis. White matter lesions that mimic those of multiple sclerosis may be detected in both normal volunteers and patients harbouring different diseases. Virtually all the characteristic features of multiple sclerosis are sometimes encountered in other conditions affecting predominantly the white matter. Different conditions such as vasculitis, subcortical atherosclerotic leukoencephalopathy, Lyme disease, or acute disseminated encephalomyelitis can be virtually indistinguishable from multiple sclerosis on conventional MR images. Also the FLAIR technique adds little to the differential diagnosis. The calculation of magnetisation transfer ratio (MT ratio) may be useful to better characterise some entities, such as vasculitis, from multiple sclerosis.

Progressive brain failure after diffuse hypoxic ischemic brain injury: a serial MR and proton MR spectroscopic study

The findings at sequential MR imaging and proton MR spectroscopy of a patient with profound hypoxic-ischemic brain injury are reported. The pattern of structural and biochemical changes observed closely reflected the known evolution of postasphyxic brain degeneration. Particularly noteworthy were the sharp decrease of cortical N-acetylaspartate in the acute phase, suggesting the severity of the neuronal insult, and the subsequent progressive increase of choline, paralleling the delayed degeneration of white matter.

Recurrent acute transverse myelopathy associated with anticardiolipin antibodies

In three patients with recurrent episodes of acute transverse myelopathy, spinal MR imaging during each episode showed areas of hyperintensity on proton density- and T2-weighted images with inconsistent contrast enhancement. Cranial MR imaging, laboratory screenings, and CSF analysis showed only increased titers of anticardiolipin antibodies. Although a causative role in neurologic conditions has not been established conclusively, an association between these antibodies and acute transverse myelopathy and its recurrences cannot be ignored.

Benign versus secondary-progressive multiple sclerosis: the potential role of proton MR spectroscopy in defining the nature of disability

PURPOSE

We determined the clinical utility of proton MR spectroscopy in defining the extent of disability in benign versus secondary-progressive multiple sclerosis (MS).

METHODS

Thirty patients with clinically definite MS, including 16 patients with benign MS and 14 with secondary-progressive MS, and a group of 13 healthy volunteers were studied with combined stimulated-echo acquisition mode proton MR spectroscopy and MR imaging (all patients received contrast material).

RESULTS

Acute enhancing lesions of benign and secondary-progressive MS were characterized by a reduction in N-acetylaspartate (NAA)/choline and NAA/creatine and an increase in inositol compounds/creatine as compared with normal white matter. Such variations were also detected in chronic unenhancing lesions in patients with secondary-progressive MS, although they were not found in chronic unenhancing lesions in patients with benign MS. Chronic lesions of the two forms of the disease have significative differences in NAA and inositol signals.

CONCLUSION

Proton MR spectroscopy is able to show metabolic changes occurring in the white matter of patients with MS. Such changes differ according to the phase (acute versus chronic) and the clinical form (benign versus secondary-progressive) of the disease.

Brain magnetic resonance imaging in congenital hypothyroid infants at diagnosis

The aim of our study was to investigate the central nervous system (CNS) morphology and myelination with magnetic resonance imaging (MRI) in congenital hypothyroid (CH) infants detected by neonatal screening before replacement therapy. We studied 11 CH infants, 9 girls and 2 boys, mean age 22 days, 3 with aplasia, 5 with ectopia, 2 with hypoplasia of the thyroid gland, 1 with unknown diagnosis. As normal controls 22 term newborns (38 to 41 weeks of gestational age) were studied. MRI studies were performed with a 1.5-T magnet, extremity coil, T1-weighted and heavily T2-sequences axial sections were obtained. No sedation was needed for the MRI studies. MRI brain examination was normal in all patients compared with controls. In particular, no differences in the myelination patterns of the brain were observed between normal subjects and patients with hypothyroidism. Our study shows no morphological brain abnormalities in CH infants detected by neonatal screening before replacement therapy. Perinatal hypothyroidism seems to have no effect on CNS structures.

Brain and spinal cord MR in benign multiple sclerosis: a follow-up study

We performed a clinical and magnetic resonance (MR) longitudinal study in 19 patients with benign multiple sclerosis (MS) to achieve a better definition of the nature of disability in MS. Patients with higher lesion volumes on conventional T2-weighted images at entry were those with more frequent relapses (p = 0.0004) and more new MR lesions (p = 0.003) during the follow up. However, 1/3 of these new lesions were located periventricularly and about 2/3 were small or intermediate in size. Two of the 11 patients (18%) with higher lesion volumes at entry developed progressive neurological deficits: in these two patients the new lesions seen on conventional T2 images had lower magnetization transfer ratios (p = 0.005) than those present in patients who remained clinically stable and a marked increase in hypointense lesion volumes on T1-weighted images was also found. Spinal cord cross-sectional area at C5 and MTR values for the seemingly normal white matter were similar to those found in normal controls. This study suggests that patients with benign MS have two different patterns of disease evolution, one characterized by very low clinical and MR activities, the other in which the lack of disabling symptomatology might be related to factors like site, size and nature of lesions. It also indicates that in patients with benign MS and high MR lesion loads the risk of developing a secondary progressive form of the disease is still present even after many years after onset.

Proton magnetic resonance spectroscopy and intracranial tumours: clinical perspectives

Proton magnetic resonance spectroscopy (1H-MRS) was applied to characterize intracranial tumours of different hystological types. Seventy patients with intracranial neoplasms were studied before receiving surgery, radiotherapy or chemotherapy. All tumours were characterized by reduced or absent N-acetylasparate and increased signal from choline-containing compounds. Distinctive patterns were observed only for primitive brain neoplasms; high-grade gliomas were differentiated from low-grade ones by higher levels of choline-containing compounds. The metabolic aspects of metastatic lesions were similar to high-grade gliomas. These results, together with the limitations of 1H-MRS and future applications are reviewed.

Correlation between brain MRI lesion volume and disability in patients with multiple sclerosis

In this study we evaluated the relationships between clinical variables and lesion volumes measured from magnetic resonance imaging (MRI) scans in a large cohort of multiple sclerosis (MS) patients. One hundred and thirty patients with MS entered the study: 36 patients had relapsing-remitting (RR), 39 benign (B), 42 secondary progressive (SP) and 13 primary progressive (PP) courses. There was a significant correlation (r = 0.3; p = 0.0006) between the total lesion load and the EDSS score when the whole cohort of patients was considered. This correlation increased (r = 0.5) when only patients with RRMS and SPMS were considered. Our data indicate that a correlation between disability and MRI lesion volume in MS exists, but its strength is moderate.

Endovascular treatment of bacterial intracranial aneurysms

We report three patients with bacterial intracranial aneurysms treated by the endovascular approach: two presented with sudden severe neurological deficits after a diagnosis of endocarditis; the other had suspected vasculitis. CT showed an intracerebral haematoma in all cases; angiography revealed bacterial aneurysms of distal branches of the middle cerebral artery in one. Because of the patients' condition and the location of the aneurysms, endovascular treatment was considered the fastest and safest treatment. Hyperselective catheterisation of the parent branch, close to the aneurysm, was performed with a microcatheter. A small amount of glue was injected to occlude both the aneurysm and a short segment of the diseased vessel. Follow-up angiography revealed occlusion of the aneurysm in all cases. One patient recovered completely; one recovered over some months, with neurological deficit due to the haematoma. The third patient suddenly worsened and died 9 days after treatment for a contralateral haematoma, due to rupture of a new bacterial aneurysm of the middle cerebral artery. Endovascular occlusion of the aneurysm and parent vessel may be an alternative to surgery in selected, severe cases of deep or distal bacterial intracranial aneurysms.

Magnetisation transfer ratios of contrast-enhancing and nonenhancing lesions in multiple sclerosis

Magnetisation transfer (MT) is a recently introduced technique for assessing the water content of tissues in vivo and its relationship to macromolecules or membranes. It has been suggested that MT could provide indirect evidence of the characteristics of multiple sclerosis (MS) lesions (oedema, demyelination, or gliosis). Our aims were to characterise brain MS lesions and to compare the magnetisation transfer ratio (MTR) values of lesions with different patterns of contrast enhancement. In patients with MS we measured the MTR of 65 gadolinium-enhancing and 292 nonenhancing lesions. Using the equation published by Dousset et al. we studied 29 patients with clinically definite MS and 10 healthy controls. Lesions had significantly lower MT than the normal-appearing white matter of the patients or the normal white matter of healthy controls. There was no difference in the MTR of enhancing and nonenhancing lesions. Enhancement was homogeneous in 45 and ring-like in 20 lesions; MTR values were lower in the latter. These findings are presumably related to the differences in pathological features of enhancing (different amounts of proteins and inflammatory cells, oedema and demyelination) and nonenhancing (gliosis, demyelination and axonal loss) lesions.

Comparison of triple dose versus standard dose gadolinium-DTPA for detection of MRI enhancing lesions in patients with MS

We studied whether a triple dose of gadolinium-DTPA alone or in combination with delayed scanning increases the sensitivity of brain MRI for detecting enhancing lesions in patients with MS. We obtained T1-weighted brain MRI scans in two sessions for 22 patients with clinically definite MS. In the first session, we obtained one scan 5 to 7 minutes after the injection of 0.1 mmol/kg gadolinium-DTPA (standard dose). In the second session, 6 to 24 hours later, we obtained one scan before the two scans 5 to 7 minutes (for all patients) and one hour (for 11 patients) after the injection of 0.3 mmol/kg gadolinium-DTPA (triple dose). We detected 83 enhancing lesions in 14 patients when the standard dose of gadolinium-DTPA was used. The numbers of enhancing lesions increased to 138 (average increase 66%; p = 0.001) and the numbers of patients with such lesions to 18 (increase 28%) when we used the triple dose of gadolinium-DTPA. In addition, the total area per patient occupied by such lesions was greater (p < 0.0001) and lesion signal intensity higher (p = 0.0001) on the triple-dose scans than the standard-dose scans. There was an increase in the number of large enhancing lesions (p = 0.03) in the scans obtained 1 hour after the injection of the triple dose of gadolinium-DTPA. These data indicate that in patients with MS, a triple dose of gadolinium-DTPA can reveal many more enhancing lesions, which also appear larger. This suggests that the pathologic nature of "active" lesions in MS is heterogeneous, which might have impact on planning clinical trials.

Antenatal diagnosis of vein of Galen aneurysmal malformation: MR study of fetal brain and postnatal follow-up

About 20 cases of prenatal diagnosis of vein of Galen aneurysmal Malformation (VGAM) have been described. We present a case diagnosed prenatally by Doppler ultrasonography. Prenatal MRI and postnatal radiological studies including post-treatment MRI and MRA, were carried out.

Comparison of triple dose versus standard dose gadolinium-DTPA for detection of MRI enhancing lesions in patients with primary progressive multiple sclerosis

This study was performed to evaluate whether a triple dose of gadolinium-DTPA (Gd-DTPA) increases the sensitivity of brain MRI for detecting enhancing lesions in patients with primary progressive multiple sclerosis (PPMS). T1 weighted brain MRI was obtained for 10 patients with PPMS in two sessions. In the first session, one scan was obtained five to seven minutes after the injection of 0.1 mmol/kg Gd-DTPA (standard dose). In the second session, six to 24 hours later, one scan before and two scans five to seven minutes and one hour after the injection of 0.3 mmol/kg Gd-DTPA (triple dose) were obtained. Four enhancing lesions were detected in two patients when the standard dose of Gd-DTPA was used. The numbers of enhancing lesions increased to 13 and the numbers of patients with such lesions to five when the triple dose of Gd-DTPA was used and to 14 and six in the one hour delayed scans. The mean contrast ratio for enhancing lesions detected with the triple dose of Gd-DTPA was higher than those for lesions present in both the standard dose (P < 0.0009) and the one hour delayed scans (P = 0.04). These data indicate that with a triple dose of Gd-DTPA many more enhancing lesions can be detected in patients with PPMS. This is important both for planning clinical trials and for detecting the presence of inflammation in vivo in the lesions of such patients.

An elastic computerized brain atlas for the analysis of clinical PET/SPET data

An elastic computerized brain atlas was developed for the analysis of positron emission tomography/single-photon emission tomography (PET/SPET) data. It consists of a set of digital anatomical contours and a template of regions of interest, schematically describing the brain, derived from a currently used anatomical/functional brain atlas. A warping algorithm, matching equivalent contours, was implemented to elastically fit the atlas to individual brain images. The elastic computerized brain atlas was applied to representative magnetic resonance imaging (MRI)-PET/SPET studies, MRI providing the anatomical information used by the matching procedure. The atlas is suited for clinical use in a nuclear medicine environment.

Spontaneous involution of optic pathway lesions in neurofibromatosis type 1: serial contrast MR evaluation

PURPOSE

To evaluate with contrast MR the evolution in size, signal, and contrast enhancement of optic pathway lesions in four patients with neurofibromatosis type 1.

METHODS

The four reported patients are children with ages ranging from 21 months to 13 years affected by neurofibromatosis type 1 and optic pathway lesions. No treatment of the optic pathway lesions was carried out in these patients. They have been followed by serial contrast MR.

RESULTS

In all patients a change in size, signal, and enhancement of optic pathways lesions was noted with time, and in the last follow-up study a marked reduction in size and enhancement of optic pathway lesions was observed in all cases.

CONCLUSIONS

Modification and regression of optic pathway lesions with spontaneous disappearance of the enhancement is demonstrated. This finding could have a crucial influence on the therapeutic approach of the optic pathway lesions.

Transitional progressive multiple sclerosis: MRI and MTI findings

Transitional progressive multiple sclerosis (MS) is quite an unusual form of presentation and course of the disease. A case with this progressive form is presented and brain MRI and MTI findings are discussed in relation to the possible insight they may provide for understanding the mechanisms that determine progressive disability in MS.

Acute subarachnoid haemorrhage: 3D time-of-flight MR angiography versus intra-arterial digital angiography

To evaluate the efficacy and reliability of 3D time-of-flight MR angiography (TOF MRA) as a noninvasive procedure, 27 patients with acute subarachnoid haemorrhage (SAH) were studied with MRA immediately before or after intra-arterial digital subtraction angiography (DSA).3DTOF MRA was performed with an axial slab of 60 mm centered on the circle of Willis and isotropic voxels. DSA showed 22 aneurysms and 1 dural arteriovenous fistula in 21 patients; the aneurysms ranged in size from 2 to 8mm. MRA failed to show 2 small aneurysms, at the origin of the posterior and anterior communicating arteries. The 3D display of the intracranial vessels obtained with maximum intensity projection (MIP) or targetted MIP sometimes rendered the aneurysms better than DSA. However, due to its high spatial resolution, DSA more clearly defined the overall anatomy of the walls of the normal and abnormal vessels.

A brain MRI study of different types of chronic-progressive multiple sclerosis

INTRODUCTION

This study was performed to define the pattern of brain magnetic resonance imaging (MRI) abnormalities in chronic-progressive MS (MS).

MATERIAL AND METHODS

Brain MRIs were obtained for 17 patients with secondary progressive MS (SPMS), 14 with primary progressive MS (PPMS) and 5 with "transitional" progressive MS (TPMS).

RESULTS

Total lesion loads were different for the three groups of patients (p < 0.01). At post-hoc analysis, there was no difference between patients with TPMS and those with PPMS, while both these groups had lesion loads lower than those of patients with SPMS. Patients with PPMS with clinical signs indicating involvement of both brain and spinal cord had greater total lesion loads than those with clinical isolated spinal cord involvement (p < 0.05).

CONCLUSION

These data indicate that brain MRI patterns of abnormalities are related to the clinical manifestations in patients with chronic-progressive MS.

A magnetization transfer imaging study of normal-appearing white matter in multiple sclerosis

We attempted to define the role of subtle changes in the normal-appearing white matter (NAWM) in the development of disability in multiple sclerosis (MS). Twenty-seven clinically definite MS patients with either relapsing-remitting or chronic-progressive courses and 10 sex- and age-matched controls entered the study. For each patient and control, we studied two NAWM areas in the frontal lobe with magnetization transfer imaging (MTI). For patients, we also calculated the MT ratios (MTRs) for three contiguous areas of NAWM progressively further from "isolated" lesions visible on conventional MRI. Frontal NAWM in MS patients had lower mean MTRs than the frontal white matter of the controls (p = 0.02). MTRs in the NAWM adjacent to isolated lesions increased with distance from them to the cortical gray matter (p = 0.04). This pattern was typical for patients with chronic-progressive MS whose MTRs in the first two regions of NAWM adjacent to lesions were lower than those of the same regions of patients with relapsing-remitting MS. This study confirms that there are alterations in the NAWM of MS patients and suggests that such changes might be relevant to the disability in MS.

Acute transverse myelopathy: spinal and cranial MR study with clinical follow-up

PURPOSE

To evaluate the contribution of MR in determining the cause of acute transverse myelopathy, to determine the frequency and types of the intracranial lesions detectable on MR at the onset of the disease, and to monitor clinical and MR evolution of the disease.

METHODS

Spinal and cranial MR images were obtained for 30 patients with acute transverse myelopathy. Gadopentetate dimeglumine was administered in 10 patients. Mean follow-up time was 18 months.

RESULTS

Spinal cord MR findings were abnormal in 14 of 30 patients. The abnormal MR can be divided into group A, in which one segment was involved (8 patients), and group B, in which more than one segment was involved (6 patients). In both groups there were 2 patients with enhancing lesions. Enhancement was less homogeneous in the group B patients. Enhancement did not change with increased length of lesion. At follow-up, the diagnostic categories of the patients were multiple sclerosis (8 patients), encephalomyelitis (1 patient), viral myelitis (3 patients), and myelopathy of unknown cause (18 patients). After the episode of acute transverse myelopathy, in 4 of 8 patients in group A and in 4 of 5 patients with normal spinal MR but abnormal brain MR findings clinical signs of multiple sclerosis developed. In no patients in group B did multiple sclerosis develop. The final diagnoses for the 4 patients with gadolinium-enhancing spinal lesions were myelopathy of unknown cause (2 patients), multiple sclerosis (1 patient), and viral myelitis (1 patient).

CONCLUSION

MR contributed to establishing the diagnosis in 40% of our cases.