title: Monitoring early response of lymph node metastases to radiotherapy in animal models: diffusion-weighted imaging vs. morphological MR imaging.
abstract: BACKGROUND
  Diffusion-weighted imaging (DWI) offers a non-invasive technique that can reveal microscopic details about the architecture of both normal and anomalous tissues. Some studies have confirmed DWI can detect the early changes of tumors that have originated from various organs, even after treatment.
  
  
  OBJECTIVE
  To compare the usefulness of apparent diffusion coefficient (ADC) and morphologic magnetic resonance (MR) imaging for monitoring the therapeutic response of metastatic disease in lymph nodes to radiotherapy.
  
  
  METHODS
  Twenty-six rabbits (metastatic, n = 17; non-metastatic, n = 9) were divided into group A (metastatic, n = 10), group B (metastatic, n = 7) and group C (non-metastatic, n = 9). Groups A and C underwent irradiation, whereas group B was set as a reference. Standard MR imaging and DWI were performed before and 1, 3, and 7 days after radiotherapy for all rabbits. The lymph node volumes and ADCs were measured and evaluated with repeated measures ANOVA. The difference between group A and B was analyzed using Student's t-test.
  
  
  RESULTS
  In all rabbits, a total of 35 lymph nodes were found, including 16 nodes in group A, 10 in group B and nine in group C. In group A, 3 and 7 days after therapy ADCs were significantly higher than pre-treatment and 1 day after therapy (P < 0.05). For groups A and B, a significant difference of ADCs was present 7 days after therapy. A significant difference of variation of ADCs among the three groups was also present (P < 0.001).
  
  
  CONCLUSIONS
  DWI is superior to morphological MRI in monitoring early radiation response in animal models.
authors: Department of Radiology, Third Affiliated Hospital of SooChow University, Changzhou First Hospital, Jiangsu Province, Changzhou, China.
authors: Jie
authors: J
authors: Chen
authors: Jing
authors: J
authors: Sheng
authors: Wei
authors: W
authors: Xing
authors: Hussein
authors: H
authors: Aoun
authors: Ming
authors: M
authors: Chen
authors: Heng-Liang
authors: HL
authors: Bi
authors: Jian-Ming
authors: JM
authors: Tian
authors: Yong-Ming
authors: YM
authors: Dai
mesh_terms: D000818:Animals; D038524:Diffusion Magnetic Resonance Imaging; D008207:Lymphatic Metastasis / Q000175:diagnosis* / Q000473:pathology / Q000532:radiotherapy*; D008279:Magnetic Resonance Imaging; D008991:Monitoring, Physiologic; D011817:Rabbits