Lescher Stephanie, Jurcoane Alina, Veit Andreas, Bähr Oliver, Deichmann Ralf, Hattingen Elke
Institute of Neuroradiology, Hospital of Goethe University, Schleusenweg 2-16, Frankfurt am Main, Germany,
Neuroradiology. 2015 Jan;57(1):11-20. doi: 10.1007/s00234-014-1445-9. Epub 2014 Oct 7.
Treatment with the humanized anti-vascular endothelial growth factor (VEGF) antibody bevacizumab in glioblastoma patients suppresses contrast enhancement via the reduction of vascular permeability, which does not necessarily indicate real reduction of tumor cell mass. Therefore, other imaging criteria are needed to recognize tumor growth under bevacizumab more reliably. It is still unknown, whether quantitative T1 mapping is useful to monitor the effects of anti-angiogenic therapy or to indicate a tumor progression earlier and more reliable compared to conventional magnetic resonance imaging (MRI) sequences. This raised the question whether quantitative T1 mapping is more suitable to monitor treatment effects of bevacizumab.
Conventional and quantitative MRI was performed on six consecutive patients with recurrent glioblastoma before treatment with bevacizumab and every 8 weeks thereafter until further tumor progression. Quantitative T1 maps before and after intravenous application of contrast agent and quantitative T2 maps were performed to calculate serial differential maps and subtraction maps from one time point, subtracting contrast-enhanced T1 maps from non-contrast T1 maps.
In five illustrative cases, tumor progression was documented earlier in differential T1 relaxation time (DiffT1) and T2 relaxation time (DiffT2) maps before changes in the conventional MRI studies were obvious. Four patients showed previous prolongation of T1 relaxation time in the DiffT1 maps, suggesting tumor progression, and subtraction maps revealed faint contrast enhancement matching with the areas of T1 prolongation.
Our results emphasize that quantitative relaxation time mapping could be a promising method for tumor monitoring in glioblastoma patients under anti-angiogenic therapy. Quantitative T1 mapping seems to detect enhancing tumor earlier than conventional contrast-enhanced T1-weighted images.
胶质母细胞瘤患者使用人源化抗血管内皮生长因子（VEGF）抗体贝伐单抗治疗可通过降低血管通透性来抑制对比增强，但这不一定表明肿瘤细胞团真正减少。因此，需要其他影像学标准来更可靠地识别贝伐单抗治疗下的肿瘤生长。定量T1成像是否有助于监测抗血管生成治疗的效果，或者与传统磁共振成像（MRI）序列相比，是否能更早、更可靠地提示肿瘤进展，目前尚不清楚。这就引出了一个问题，即定量T1成像是否更适合监测贝伐单抗的治疗效果。
对6例复发性胶质母细胞瘤患者在接受贝伐单抗治疗前及治疗后每8周进行一次常规和定量MRI检查，直至肿瘤进一步进展。在静脉注射造影剂前后进行定量T1成像，并进行定量T2成像，以计算连续的差分图和减法图，即将非增强T1图减去增强T1图。
在5个典型病例中，在传统MRI研究出现明显变化之前，在差分T1弛豫时间（DiffT1）和T2弛豫时间（DiffT2）图中更早记录到肿瘤进展。4例患者的DiffT1图中先前出现T1弛豫时间延长，提示肿瘤进展，减法图显示与T1延长区域匹配的微弱对比增强。
我们的结果强调，定量弛豫时间成像可能是监测抗血管生成治疗下胶质母细胞瘤患者肿瘤的一种有前景的方法。定量T1成像似乎比传统的增强T1加权图像更早检测到强化肿瘤。
