How Computed Tomography Contrast Media and Magnetic Resonance Imaging Contrast Media Affect the Changes of Uptake Counts of Tl-201

Abstract

The purpose of the study is to investigate how uptake counts of Tl-201 of radioisotopes in the human body could change, when taking computed tomography and magnetic resonance imaging right after injecting contrast media. Tl-201 radioisotope substances of iodine contrast medium, which is a computed tomography contrast medium, and paramagnetic contrast medium, which is an magnetic resonance imaging contrast medium, were used as study materials. First, Tl-201 was put into 4 cc of normal saline in test tube, and then a computed tomography contrast medium of lopamidol (R) or Dotarem (R), was put into 2 cc of normal saline in test tube. An magnetic resonance imaging contrast medium of Primovist (R) or Gadovist (R) was also put into 2 cc of normal saline in test tube. Each contrast medium was distributed to make Tl-201 as 3 mCi, with a total of 4 cc. Gamma camera, low energy high resolution collimator, and pinhole collimator were used to obtain images. The uptake count of Tl-201 was measured with 1000 frames of images, and obtained after 10 times of repetition. This study revealed that the use of Gadovist (R), which is an magnetic resonance imaging contrast medium, showed the smallest number of uptake count, after measuring Tl-201 uptake count by low energy high resolution collimator. On the other hand, the use of lopamidol (R), which is a computed tomography contrast medium, showed the biggest difference in uptake count, when measuring Tc-99m uptake count by Pinhole collimator. When examining with gamma camera, using contrast medium and Tl-201, identifying the changes of uptake count is very important for improving the value of diagnosis.