A study on quantitative analyses before and after injection of contrast medium in spine examinations performed by using diffusion weighted image

Abstract

This study examined the changes in the signal-to-noise ratio (SNR), the contrast-to-noise ratio (CNR) and the apparent diffusion coefficient (ADC) of metastatic cancer in the lumbar region by using diffusion weighted image taken with a 1.5 T (Tesla) magnetic resonance (MR) scanner before and after injecting a contrast medium. The study enrolled 30 healthy people and 30 patients with metastatic spine cancer from patients who underwent a lumbar MRI scan from January 2011 to October 2012. A 1.5 T MR scanner was used to obtain the diffusion weighted images (DWIs) before and after injecting the contrast medium. In the group with metastatic spine cancer, the SNR and the CNR were measured in three parts among the L1-L5 lumbar vertebrae, which included the part with metastatic spine cancer, the area of the spine with spine cancer, and the area of spine under the region with cancer. In the acquired ADC map image, the SNRs and the ADCs of the three parts were measured in ADC map images. Among the healthy subjects, the measurements were conducted for the lumbar regions of L3-L5. According to the results, in the group with metastatic spine cancer, the SNR in the DWI before the contrast medium had been injected was lowest in the part with spine cancer. In the DWI after the contrast medium had been injected, the SNR and the CNR were increased in all three parts. In the ADC map image after the contrast medium had been injected, the SNR decreased in all three parts compared to the SNR before the contrast had been injected. The ADC after had been injected the contrast medium was decreased in all three parts compared to that before the contrast medium had been injected. In the healthy group, the SNR was increased in the L3-L5 lumbar regions in the DWI. In the ADC map image, the SNR in all the three parts was decreased in the DWI after injecting the contrast medium had been injected. The ADC in the ADC map image was also decreased in all three parts.