Department of Radiology, Technische Universität München, Munich, Germany.
J Nucl Med. 2010 Nov;51(11):1691-8. doi: 10.2967/jnumed.110.077719. Epub 2010 Oct 18.
Both dynamic contrast-enhanced (DCE) MRI and PET provide quantitative information on tumor biology in living organisms. However, imaging biomarkers often neglect tissue heterogeneity by focusing on distributional summary statistics. We analyzed the spatial relationship of α(v)β(3) expression, glucose metabolism, and perfusion by PET and DCE MRI, focusing on tumor heterogeneity.
Thirteen patients with primary or metastasized cancer (non-small cell lung cancer, n = 9; others, n = 4) were examined with DCE MRI and with PET using (18)F-galacto-RGD and (18)F-FDG. Twenty-three different regions of interest were defined by cluster analysis based on the heterogeneity of tracer uptake. In these regions, the initial area under the gadopentetate dimeglumine concentration-time curve (IAUGC), as well as the regional blood volume (rBV) and regional blood flow (rBF), were estimated from DCE MRI and correlated with standardized uptake values from PET.
Regions with simultaneously high uptake of (18)F-galacto-RGD and (18)F-FDG showed higher functional MRI data (IAUGC, 0.35 ± 0.04 mM·s; rBF, 70.2 ± 12.7 mL/min/100 g; rBV, 23.3 ± 2.7 mL/100 g) than did areas with low uptake of both tracers (IAUGC, 0.15 ± 0.04 mM·s [P < 0.01]; rBF, 28.3 ± 10.8 mL/min/100 g; rBV, 9.9 ± 1.9 mL/100 g [P < 0.01]). There was a weak to moderate correlation between the functional MRI parameters and (18)F-galacto-RGD (r = 0.30-0.62) and also (18)F-FDG (r = 0.44-0.52); these correlations were significant (P < 0.05), except for (18)F-galacto-RGD versus rBF (P = 0.17).
These data show that multiparametric assessment of tumor heterogeneity is feasible by combining PET and MRI. Perfusion is highest in tumor areas with simultaneously high α(v)β(3) expression and high glucose metabolism and restricted in areas with both low α(v)β(3) expression and low glucose metabolism. The current limitations resulting from imaging with separate scanners might be overcome by future hybrid PET/MRI scanners.
通过 DCE MRI 和 PET 分析 α(v)β(3)表达、葡萄糖代谢和灌注的空间关系，重点研究肿瘤异质性。
13 例原发性或转移性癌症患者（非小细胞肺癌 9 例，其他 4 例）接受 DCE MRI 和（18）F-半乳糖-RGD 和（18）F-FDG PET 检查。根据示踪剂摄取的异质性，通过聚类分析定义了 23 个不同的感兴趣区。在这些区域，从 DCE MRI 估计初始钆喷酸二甲葡胺浓度-时间曲线下面积（IAUGC），以及局部血容量（rBV）和局部血流量（rBF），并与 PET 的标准化摄取值相关。
同时摄取高浓度（18）F-半乳糖-RGD 和（18）F-FDG 的区域显示出更高的功能 MRI 数据（IAUGC，0.35±0.04 mM·s；rBF，70.2±12.7 mL/min/100 g；rBV，23.3±2.7 mL/100 g），高于同时摄取两种示踪剂的低浓度区域（IAUGC，0.15±0.04 mM·s[P<0.01]；rBF，28.3±10.8 mL/min/100 g；rBV，9.9±1.9 mL/100 g[P<0.01]）。功能 MRI 参数与（18）F-半乳糖-RGD（r=0.30-0.62）和（18）F-FDG（r=0.44-0.52）之间存在弱到中度相关性；这些相关性具有统计学意义（P<0.05），除了（18）F-半乳糖-RGD 与 rBF 之间（P=0.17）。
这些数据表明，通过结合 PET 和 MRI 对肿瘤异质性进行多参数评估是可行的。在同时高表达 α(v)β(3)和高葡萄糖代谢的肿瘤区域，灌注最高，而在同时低表达 α(v)β(3)和低葡萄糖代谢的肿瘤区域，灌注受限。目前由于使用单独的扫描仪而导致的限制，可能会被未来的 PET/MRI 混合扫描仪所克服。
