Lasocki Arian, McArthur Grant A
Department of Cancer Imaging, Peter MacCallum Cancer Centre.
Sir Peter MacCallum Department of Oncology, The University of Melbourne.
Melanoma Res. 2022 Oct 1;32(5):373-378. doi: 10.1097/CMR.0000000000000847. Epub 2022 Aug 17.
BRAF V600 mutations (BRAF mut ) are associated with more pigmentation in primary melanomas, but data on melanin content of metastases are limited. This study compares signal characteristics of BRAF mut and BRAF-wildtype (BRAF wt ) intracranial melanoma metastases (IMM). MRI brain examinations at first diagnosis of IMM were identified, all performed at 3-Tesla including 1 mm volumetric pre- and postcontrast T1-weighted imaging and susceptibility-weighted imaging (SWI). Individual metastases were assessed by a neuroradiologist, stratified by size (≥10 mm, 'larger', vs. 2-9 mm, 'small'; up to 10 per group); presence of intrinsic T1-hyperintensity (T1H) and, if present, whether confidently attributable to melanin as opposed to haemorrhage; evidence of haemorrhage; presence of central necrosis. A total of 267 IMM in 73 patients were assessed (87 larger IMM, 180 small). The proportion of larger IMM was similar in both groups (31% BRAF mut and 36% BRAF wt ). In small IMM, MRI evidence of melanin was more common in BRAF mut patients (42% vs. 26%; P = 0.038). Haemorrhage was more common in larger IMM (51%, vs. 20% of small IMM; P < 0.0001), but did not differ based on BRAF status. Central necrosis was more common in larger IMM (44% vs. 7%; P < 0.0001) and in BRAF mut IMM (23% vs. 11%; P = 0.011). In the BRAF mut cohort, central necrosis was more common in patients without previous anti-BRAF therapy (33% vs. 7%; P = 0.0001). T1H attributable to melanin is only slightly more common in BRAF mut IMM than BRAF wt . Higher rates of central necrosis in BRAF mut patients without previous anti-BRAF therapy suggest that anti-BRAF therapy may affect the patterns of IMM growth.
BRAF V600突变（BRAF mut）与原发性黑色素瘤中更多的色素沉着相关，但关于转移灶黑色素含量的数据有限。本研究比较了BRAF mut和BRAF野生型（BRAF wt）颅内黑色素瘤转移灶（IMM）的信号特征。确定了初次诊断IMM时的脑部MRI检查，所有检查均在3特斯拉进行，包括1毫米容积的对比剂前和对比剂后T1加权成像以及磁敏感加权成像（SWI）。由神经放射科医生评估单个转移灶，按大小分层（≥10毫米，“较大”，与2 - 9毫米，“较小”；每组最多10个）；是否存在固有T1高信号（T1H），如果存在，是否可明确归因于黑色素而非出血；出血证据；中央坏死情况。共评估了73例患者的267个IMM（87个较大IMM，180个较小IMM）。两组中较大IMM的比例相似（BRAF mut组为31%，BRAF wt组为36%）。在较小IMM中，BRAF mut患者黑色素的MRI证据更常见（42%对26%；P = 0.038）。出血在较大IMM中更常见（51%，而较小IMM为20%；P < 0.0001），但基于BRAF状态无差异。中央坏死在较大IMM中更常见（44%对7%；P < 0.0001），在BRAF mut IMM中也更常见（23%对11%；P = 0.011）。在BRAF mut队列中，未接受过BRAF治疗的患者中央坏死更常见（33%对7%；P = 0.0001）。归因于黑色素的T1H在BRAF mut IMM中仅比BRAF wt略常见。未接受过BRAF治疗的BRAF mut患者中央坏死率较高，提示BRAF治疗可能影响IMM的生长模式。
