Tumor Blood Volume Determination by Using Susceptibility-corrected Delta R2(star) Multiecho MR

作者：Persigehl Thorsten^*; Wall Alexander; Kellert Julia; Ring Janine; Remmele Stefanie; Heindel Walter; Dahnke Hannes; Bremer Christoph

来源：Radiology, 2010, 255(3): 781-789.

DOI：10.1148/radiol.10090832

Purpose: To evaluate a susceptibility-corrected multiecho magnetic resonance (MR) relaxometry technique for an accurate and robust determination of Delta R2(star) as a noninvasive surrogate parameter of the perfused tumor blood volume.
Materials and Methods: All experiments were approved by the institutional animal care committee. In a glass tube phantom with different superparamagnetic iron oxide (SPIO) particle concentrations and at tumor mice xenografts with DU-4475, HT-1080, and MDA-MB-435 tumors (n = 15 total, n = 5 per model) with different degrees of neovascularization after injection of different ultrasmall SPIO (USPIO) doses changes of the transverse relaxation rate (Delta R2(star)) were determined by using a fixed echo time (TE) of 22 msec and a susceptibility-corrected multigradient-echo technique. The mean Delta R2(star) value and the vascular volume fraction (VVF) of each tumor was determined and compared with independent in vivo fluorescent tumor perfusion measurements and histologic analysis helped determine microvessel density (MVD). Statistical differences were tested by using analysis of variance and linear correlations.
Results: For the phantom study, Delta R2(star) maps calculated with a fixed TE of 22 msec showed a higher standard deviation of the noise index compared with the susceptibility-corrected multiecho technique. For the xenograft model, mean tumor Delta R2(star) values (+/- standard error of the mean) showed signifi cant differences between the various tumors (eg, DU-4475: 12.3 sec(-1) +/- 2.67, HT-1080: 36.47 sec(-1) +/- 5.84, and MDA-MB-435: 64.01 sec(-1) +/- 8.87 at 80 mu mol of iron per kilogram; P< .05). Delta R2(star) values increased dose dependently and in a linear fashion, resulting in reproducibly stable VVF measurements. Fluorescent tumor perfusion measurements and MVD counts corroborated the MR results.
Conclusion: Susceptibility-corrected multiecho MR relaxometry allows a highly accurate and robust determination of Delta R2(star) and VVF with an excellent dynamic range for tumor characterization at clinically relevant doses of USPIO.

• 出版日期2010-6