Assessment of Melanin Content and its Influence on Susceptibility Contrast in Melanoma Metastases.

Assessment of Melanin Content and its Influence on Susceptibility Contrast in Melanoma Metastases.

Publication date: Aug 08, 2019

To quantify the influence of melanin content on magnetic susceptibility of cerebral melanoma metastases.

Patients with non-hemorrhagic metastases were included based on the absence of susceptibility blooming artifacts. Susceptibility maps were calculated from 3D gradient echo data, using Laplacian-based phase unwrapping, sophisticated harmonic artefact reduction for phase data (V-SHARP) with varying spherical kernel sizes for background field removal and the iLSQR algorithm for the inversion of phase data. Susceptibility maps were referenced to cerebrospinal fluid. Non-hemorrhagic metastases were identified on contrast-enhanced T1-weighted images and susceptibility weighted images. Metastases masks were drawn on T1-weighted post-contrast images and used to compute mean susceptibility values of each metastasis.

A total of 33 non-hemorrhagic melanoma brain metastases in 20 patients were quantitatively evaluated. Metastases without and with hyperintense signal on T1-weighted images, which corresponds to the melanin content, showed median susceptibility values of -0.028 ppm and -0.020 ppm, respectively. The susceptibility differences between metastases without and with T1-weighted hyperintense signal was not statistically significant (p ≥ 0.05).

Non-hemorrhagic cerebral melanoma metastases showed weak diamagnetic susceptibility values and susceptibility did not significantly correlate to T1-weighted signals. Therefore, melanin does not seem to be a major contributor to susceptibility in cerebral melanoma metastases.

Straub, S., Laun, F.B., Freitag, M.T., K”olsche, C., von Deimling, A., Denoix, M., Bendszus, M., Schlemmer, H.P., Ladd, M.E., and Schneider, T.M. Assessment of Melanin Content and its Influence on Susceptibility Contrast in Melanoma Metastases. 23706. 2019 Clin Neuroradiol.

Concepts Keywords
Algorithm Magnetic resonance imaging
Cerebrospinal Fluid Diamagnetism
Diamagnetic Melanin
Gradient Melanoma
Harmonic Magnetic susceptibility
Inversion Brain tumor
Kernel Magnetic resonance imaging
Laplacian Brain metastasis
Magnetic Susceptibility Physics
Melanin Electromagnetism
Melanoma Physical sciences
Metastases Non hemorrhagic metastases
Metastasis Resonance imaging
Phase Unwrapping

Semantics

Type Source Name
gene UNIPROT SLC35G1
gene UNIPROT DESI1
gene UNIPROT SPEN
drug DRUGBANK Flunarizine
disease MESH Metastases
disease DOID Melanoma
pathway BSID Melanoma
disease MESH Melanoma

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