Automated Determination of Brain Parenchymal Fraction in Multiple Sclerosis

Vågberg, Mattias; Lindqvist, Thomas; Ambarki, Khalid; Warntjes, J. B. M.; Sundström, Peter; Birgander, Richard; Svenningsson, Anders

doi:10.3174/ajnr.a3262

Cited by 53 publications

(59 citation statements)

References 29 publications

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“…In particular, the BPF was shown to be less in this patient, which is consistent with other studies (124,125).…”

Section: Brain Tissue Segmentationsupporting

confidence: 81%

“…This estimates tissue fractions, rather than absolute volumes, such as WM fraction (WMF), GMF and CSFF. In order to overcome the problem with WM/GM separation it is possible to calculate the brain parenchymal fraction (BPF) which is the relation of WM+GM to total skull size (124,125). When calculating brain tissue fractions, however, the result is not only dependent on the brain tissue segmentation, but also on the skull stripping algorithm used (126,127).…”

Section: Brain Tissue Volumesmentioning

confidence: 99%

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Quantitative Magnetic Resonance Imaging of the Brain : Applications for Tissue Segmentation and Multiple Sclerosis

West¹

2014

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Magnetic resonance imaging (MRI) is a sensitive technique for assessing white matter (WM) lesions in multiple sclerosis (MS), but there is a low correlation between MRI findings and clinical disability. Because of this, other pathological changes are of interest, including changes in normal appearing white matter (NAWM) and diffusely abnormal white matter (DAWM). Even so, the mechanisms leading to permanent disability in MS remain unclear. In contrast to conventional MRI, quantitative MRI (qMRI) is aimed at the direct measurement of the physical tissue properties, such as the relaxation times, T1 and T2, as well as the proton density (PD). QMRI is promising for characterising and quantifying changes in MS and for brain tissue segmentation. The present work describes a novel method of qMRI for the human brain (QMAP), and a segmentation method based on this. The developed methods were validated in control subjects and MR phantoms. Furthermore, an application in diseased human brain was demonstrated in MS patients. In all, 50 healthy controls and 35 MS patients were scanned with qMRI in a total of 225 acquisitions. One major finding of this work was that qMRI was able to detect and quantify changes in the MS disease that were not visible using conventional MRI. In particular, it was found that DAWM appears to constitute an intermediate between focal white matter (WM) lesions and NAWM. These changes may be caused by pathological processes that are not entirely attributable to Wallerian degeneration. This study showed that the QMAP method had high accuracy and relatively high precision, within a clinically acceptable time. This work also demonstrated that qMRI could be used for brain tissue segmentation and volume estimation of the whole brain, using pre-defined tissue characteristics. The results showed that brain tissue segmentation had high repeatability, which was somewhat lower when different geometries were acquired or different field strengths used. In particular, small differences were found between 1.5 T and 3.0 T in deep brain structures, the cerebellum and the brain stem. This work leads the way for early clinical applications of qMRI, and the challenge for the years to come is to understand the connection between qMRI properties of the brain and underlying biology.Bildtagning med magnetresonanstomografi (MRT) är en teknik som kan användas för att upptäcka lesioner i vit substans hos patienter med multipel skleros (MS), men sambandet mellan lesioner och klinisk funktionsnedsättning är svagt. På grund av detta har intresset för andra patologiska processer i hjärnan ökat. Exempel är förändringar i vit substans som ser normal ut vid MRT (NAWM) och även så kallad diffus vit vävnad (DAWM). Det är emellertid fortfarande oklart vilka mekanismer i MS som leder till klinisk funktionsnedsättning. Med kvantitativ MRT (qMRT) kan fysiologiska egenskaper i vävnaden, som till exempel relaxationstiderna (T1 och T2) samt protontäthet (PD), mätas. QMRT kan användas för att mäta förändringar i hjärnan hos MS patienter och des...

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“…In particular, the BPF was shown to be less in this patient, which is consistent with other studies (124,125).…”

Section: Brain Tissue Segmentationsupporting

confidence: 81%

Section: Brain Tissue Volumesmentioning

confidence: 99%

Quantitative Magnetic Resonance Imaging of the Brain : Applications for Tissue Segmentation and Multiple Sclerosis

West¹

2014

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“…4,5 The quantitative nature of the method and its ability to probe multiple physical properties in a single sequence make it suitable for volumetric analysis. [6][7][8][9][10] Synthetic MR imaging has shown promising initial results for use in MS and patients with an ischemic event. 11,12 The technique is consequently gaining interest as a potentially time-efficient alternative to conventional MR imaging to visualize and quantify brain tissue properties.…”

mentioning

confidence: 99%

Clinical Feasibility of Synthetic MRI in Multiple Sclerosis: A Diagnostic and Volumetric Validation Study

Granberg¹,

Uppman

Hashim³

et al. 2016

AJNR Am J Neuroradiol

125

111

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“…Another imaging feature to evaluate with MRI in MS is the general neurodegenerative processes that occur in parallel, including diffuse WM changes and atrophy development, which are predictors of disability and short-term disease evolution in MS. [49][50][51] These changes can be more subtle and are not always easy to detect visually on conventional images, and therefore quantitative MR sequences can improve the assessment of these features. [52,53] Quantitative MR sequences for volumetric measurements have only recently emerged as part of standard MS imaging, and have not been implemented at all centres. With synthetic MR, it is possible to calculate the brain parenchymal fraction (BPF) for longitudinal follow-up of, e.g., atrophy development in MS patients.…”

Section: Mri In Msmentioning

confidence: 99%

“…With synthetic MR, it is possible to calculate the brain parenchymal fraction (BPF) for longitudinal follow-up of, e.g., atrophy development in MS patients. [53,54] …”

Section: Mri In Msmentioning

confidence: 99%

Clinical Applications of Synthetic MRI of the Brain

Blystad¹

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Magnetic Resonance Imaging (MRI) has a high soft-tissue contrast with a high sensitivity for detecting pathological changes in the brain. Conventional MRI is a time-consuming method with multiple scans that relies on the visual assessment of the neuroradiologist. Synthetic MRI uses one scan to produce conventional images, but also quantitative maps based on relaxometry, that can be used to quantitatively analyse tissue properties and pathological changes. The studies presented here apply the use of synthetic MRI of the brain in different clinical settings. In the first study, synthetic MR images were compared to conventional MR images in 22 patients. The contrast, the contrast-to-noise ratio, and the diagnostic quality were assessed. Image quality was perceived to be inferior in the synthetic images, but synthetic images agreed with the clinical diagnoses to the same extent as the conventional images. Patients with early multiple sclerosis were analysed in the second study. In patients with multiple sclerosis, contrast-enhancing white matter lesions are a sign of active disease and can indicate a need for a change in therapy. Gadolinium-based contrast agents are used to detect active lesions, but concern has been raised regarding the long-term effects of repeated use of gadolinium. In this study, relaxometry was used to evaluate whether pre-contrast injection tissue-relaxation rates and proton density can identify active lesions without gadolinium. The findings suggest that active lesions often have relaxation times and proton density that differ from non-enhancing lesions, but with some overlap. This makes it difficult to replace gadolinium-based contrast agent injection with synthetic MRI in the monitoring of MS patients. Malignant gliomas are primary brain tumours with contrast enhancement due to a defective blood-brain barrier. However, they also grow in an infiltrative, diffuse manner, making it difficult to clearly delineate them from surrounding normal brain tissue in the diagnostic workup, at surgery, and during follow-up. The contrast-enhancing part of the tumour is easily visualised, but not the diffuse infiltration. In studies three and four, synthetic MRI was used to analyse the peritumoral area of malignant gliomas, and revealed quantitative findings regarding peritumoral relaxation changes and non-visible contrast enhancement suggestive of non-visible infiltrative tumour growth. In conclusion, synthetic MRI provides quantitative information about the brain tissue and this could improve the diagnosis and treatment for patients

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Automated Determination of Brain Parenchymal Fraction in Multiple Sclerosis

Cited by 53 publications

References 29 publications

Quantitative Magnetic Resonance Imaging of the Brain : Applications for Tissue Segmentation and Multiple Sclerosis

Quantitative Magnetic Resonance Imaging of the Brain : Applications for Tissue Segmentation and Multiple Sclerosis

Clinical Feasibility of Synthetic MRI in Multiple Sclerosis: A Diagnostic and Volumetric Validation Study

Clinical Applications of Synthetic MRI of the Brain

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