用于探测肿瘤模型中辐射诱导微观结构变化的双扩散编码：与表观扩散系数和组织学比较的概念验证研究

Double Diffusion Encoding for Probing Radiation-Induced Microstructural Changes in a Tumor Model: A Proof-of-Concept Study With Comparison to the Apparent Diffusion Coefficient and Histology.

作者信息

Duchêne Gaëtan, Abarca-Quinones Jorge, Feza-Bingi Natacha, Leclercq Isabelle, Duprez Thierry, Peeters Frank

机构信息

Department of medical imaging, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, Brussels, Belgium.

MRI unit, Department of medical imaging, Cliniques Universitaires Saint-Luc, Brussels, Belgium.

出版信息

J Magn Reson Imaging. 2020 Sep;52(3):941-951. doi: 10.1002/jmri.27119. Epub 2020 Mar 8.

DOI:10.1002/jmri.27119

PMID:32147929

Abstract

BACKGROUND

Microstructure analyses are gaining interest in cancer MRI as an alternative to the conventional apparent diffusion coefficient (ADC), of which the determinants remain unclear.

PURPOSE

To assess the sensitivity of parameters calculated from a double diffusion encoding (DDE) sequence to changes in a tumor's microstructure early after radiotherapy and to compare them with ADC and histology.

STUDY TYPE

Cohort study on experimental tumors.

ANIMAL MODEL

Sixteen WAG/Rij rats grafted with one rhabdomyosarcoma fragment in each thigh. Thirty-one were imaged at days 1 and 4, of which 17 tumors received a 20 Gy radiation dose after the first imagery.

FIELD STRENGTH/SEQUENCE: 3T. Diffusion-weighted imaging, DDE with flow compensated, and noncompensated measurements.

ASSESSMENTS

To compare, after irradiation, DDE-derived parameters (intracellular fraction, cell size, and cell density) to their histological counterparts (fraction of stained area, minimal Feret diameter, and nuclei count, respectively). 2) To compare percentage changes in DDE-derived parameters and ADC. 3) To evaluate the evolution of DDE-derived parameters describing perfusion.

STATISTICAL TESTS

Wilcoxon rank sum test.

RESULTS

Intracellular fraction, cell size, and cell density were respectively lower (-24%, P < 0.001), higher (+7.5%, P < 0.001) and lower (-38%, P < 0.001) in treated tumors as compared to controls. Fraction of stained area, minimal Feret diameter, and nuclei count were respectively lower (-20%, P < 0.001), higher (+28%, P < 0.001), and lower (-34%, P < 0.001) in treated tumors. 2) The magnitude of ADC's percentage change due to irradiation (16.4%) was superior to the one of cell size (8.4%, P < 0.01) but inferior to those of intracellular fraction (35.5%, P < 0.001) and cell density (42%, P < 0.001). 3) After treatment, the magnitude of the vascular fraction's decrease was higher than the increase of flow velocity (33.3%, vs. 13.3%, P < 0.001).

DATA CONCLUSION

The DDE sequence allows quantitatively monitoring the effects of radiotherapy on a tumor's microstructure, whereas ADC only reveals global changes.

EVIDENCE LEVEL

TECHNICAL EFFICACY

Stage 4. J. Magn. Reson. Imaging 2020;52:941-951.

摘要

背景

微观结构分析在癌症磁共振成像（MRI）中越来越受到关注，可作为传统表观扩散系数（ADC）的替代方法，而ADC的决定因素仍不清楚。

目的

评估从双扩散编码（DDE）序列计算出的参数对放疗后早期肿瘤微观结构变化的敏感性，并将其与ADC和组织学结果进行比较。

研究类型

对实验性肿瘤的队列研究。

动物模型

16只WAG/Rij大鼠，每只大腿移植一个横纹肌肉瘤碎片。31只大鼠在第1天和第4天进行成像，其中17个肿瘤在首次成像后接受20 Gy的辐射剂量。

场强/序列：3T。扩散加权成像、带流动补偿的DDE以及未补偿测量。

评估

1）比较放疗后DDE衍生参数（细胞内分数、细胞大小和细胞密度）与其组织学对应参数（染色面积分数、最小费雷特直径和细胞核计数）。2）比较DDE衍生参数和ADC的百分比变化。3）评估描述灌注的DDE衍生参数的演变。

统计检验

Wilcoxon秩和检验。

结果

1）与对照组相比，治疗组肿瘤的细胞内分数、细胞大小和细胞密度分别降低（-24%，P<0.001）、升高（+7.5%，P<0.001）和降低（-38%，P<0.001）。治疗组肿瘤的染色面积分数、最小费雷特直径和细胞核计数分别降低（-20%，P<0.001）、升高（+28%，P<0.001）和降低（-34%，P<0.001）。2）放疗导致的ADC百分比变化幅度（16.4%）高于细胞大小的变化幅度（8.4%，P<0.01），但低于细胞内分数（35.5%，P<0.001）和细胞密度（42%，P<0.001）。3）治疗后，血管分数的降低幅度高于流速的增加幅度（33.3%对13.3%，P<0.001）。