Hyperperfusion of multiple sclerosis plaques characterized by 3D FSE arterial spin labelling

Demyelinating lesions behaving like aggressive tumours on advanced MRI techniques

Tumefactive demyelinating lesions are a rare disorder in which inflammatory demyelination manifests as solitary or multiple focal brain lesions (greater than 2 cm in size), which can be mistaken for glioma, lymphoma, metastasis and in some cases even brain abscess. The symptomatology of tumefactive demyelinating lesions depends on the white matter area involved and includes quickly progressing neurological deterioration of motor, sensory and visual function, praxis, language and mood impairment, as well as seizures. Recognising the key imaging features in a patient with a prior history of demyelination may expedite appropriate management. Preoperative diagnosis or at least the consideration of a demyelinating process is important to avoid unnecessary surgery. We report three patients with demyelinating lesions who presented with findings suggestive of demyelination on conventional magnetic resonance imaging studies. However, in all patients the lesions showed high perfusion and in two high permeability, which are findings generally seen with high-grade neoplasias. In rare instances, tumefactive demyelinating lesions may show increased perfusion and high permeability, imaging findings more commonly seen in high-grade gliomas. We suggest that if white matter lesions on conventional magnetic resonance imaging are compatible with tumefactive demyelinating lesions, atypical findings of high perfusion/permeability should not dissuade the radiologist from suggesting the presence of tumefactive demyelinating lesions rather than high-grade gliomas.

[Test-retest reliability of 3D spiral fast-spin-echo pseudo-continuous arterial spin labeling for cerebral perfusion imaging of subcortical gray matter in healthy adults]

OBJECTIVE

To evaluate the test-retest reliability of 3D spiral fast-spin-echo (FSE) pseudo-continuous arterial spin labeling (3D pc-ASL) for cerebral perfusion imaging of the subcortical gray matter in healthy adults in resting state.

METHODS

3D spiral FSE ASL and 3D T1-weighted fast spoiled gradient recalled echo (3D T1-FSPGR) sequences were used for cerebral perfusion imaging in 8 healthy adult subjects, and a repeat imaging examination was performed after one week. The subcortical gray matter structures including the putamen, globus pallidus, caudate nucleus, thalamus, amygdala and hippocampus were segmented on the brain structural 3D images to generate the cerebral blood flow (CBF) map. The CBF value was extracted based on the segmented images and the CBF maps. The reliability and reproducibility of the measurements were evaluated using the intraclass correlation coefficient (ICC) and Bland-Altman plot.

RESULTS

The mean ICC value of the subcortical gray matter structures was 0.88∓0.04 (range, 0.80-0.93). The Bland-Altman plot analysis demonstrated that the differences between the two measurements at all the points corresponding to the subcortical gray matter structures were within 95% CI of the limits of agreement.

CONCLUSION

3D spiral FSE pseudo-continuous ASL is a reliable method for assessing the perfusion of the cerebral subcortical gray matter structures.