MRI and pathologic findings of sequential bone change after VX2 carcinoma implantation in rabbit tibia

다국어 초록 (Multilingual Abstract)

Purpose: To observe the natural evolution of a bone tumor model by analysis of MRI findings with MRI-pathology correlation and to determine the optimal MR sequence corresponding to pathologic change.
Materials and Methods: VX2 carcinoma was implanted into the tibia of 20rabbits. The rabbits were divided into 4 groups of 5 (groups Ⅰ-Ⅳ). MRI was done at 1-week intervals, including sagittal T1-weighted (T1WI), T2-weighted (T2WI), gadolinium-enhanced fat-suppressed T1WI (GdT1WI), and diffusion-weighted imaging (DWI). After each last follow-up MRI, each group of rabbits was sacrificed at 1-week intervals from 1 week to 4 weeks. After tibias were sectioned along the same plane as the MRI, specimen radiographs were taken and MRI-pathologic correlation was done.
Results: Predominant MRI findings were as follows: low signal intensity (SI) on T1WI (n=16), low SI with high SI rim on T2WI (n=14), intermediate SI with high SI rim on DWI (n=13), patchy enhancement with defects on GdT1WI (n=18) (1 week); enlarged area of low SI on T1WI (n=15),enlarged area of low SI with high SI rim on T2WI (n=15), intermediate to high SI on DWI (n=11), rim enhancement on GdT1WI (n=7), soft tissue mass formation (n=8) (2 weeks); more enlarged area of low SI on T1WI(n=10), heterogeneous SI with central low SI on T2WI (n=7), low SI withhigh SI rim on DWI (n=8), enhancement in bone marrow and soft tissue on GdT1WI (n=6), cortex destruction (n=8) (3 weeks); large soft tissue mass and cortex destruction in all five cases on all sequences, large low SI mass with extension of low SI into bone marrow on T1WI (n=5), heterogeneous SI on T2WI (n=3) and on DWI (n=5), heterogeneous and peripheral enhancement on GdT1WI (n=5) (4 weeks).
Specimen radiograph findings were as follows: drill hole with cortex depression (n=5), periosteal reaction (n=2) (1 week); radiolucent area (n=5),periosteal reaction (n=3), soft tissue mass density (n=2) (2 weeks); cortical bone destruction (n=5), permeative medullary bone destruction (n=5),increased periosteal reaction (n=5), and soft tissue density (n=5) (3 weeks);large soft tissue mass with posterior extension (n=3), epiphyseal extension(n=3), Codman's triangle (n=3) (4 weeks).
On MRI-pathology correlation, the corresponding findings were as follows: very low SI dot on all sequences-drill hole; low SI on T1WI, T2WI-tumor cells, fibrosis (1 week); central low SI on T1WI, T2WI, GdT1WI-tumor cells with fibrosis and necrosis; peripheral high SI on T2WI, DWI,GdT1WI -edema, fibrosis (2 weeks); mixed SI with central low SI on T2WI,DWI -tumor cell nests with extensive necrosis, fibrosis; high SI on T2WI along periosteum-periosteal reaction; high SI around low SI and in bonemarrow on T2WI, DWI, GdT1WI -edema, fibrosis; low SI on T1WI in surrounding bone marrow-tumor extension (3-4 weeks).
Conclusion: MRI findings depicted the natural evolution of bone tumor accurately and correlated well with pathologic findings. Necrosis was most accurately depicted on enhanced, fat-suppressed T1-weighted images, followed by diffusion-weighted images. The extent of tumor was also well observed on enhanced, fat-suppressed T1-weighted image. Heterogeneity of the tumor, peripheral edema, and fibrosis were represented well on T2-weighted images. Diffusion-weighted imaging could be of additional value in the evaluation of bone tumor.

목차 (Table of Contents)

• Table of Contents
• ABSTRACT
• INTRODUCTION
• MATERIALS AND METHODS
• RESULTS
• DISCUSSION
• REFERENCES
• Tables
• Figure Legends