The Effect on The Result, in Case of the In-vitro Test Performance after an Imaging Test

핵의학 영상검사 후 시행된 핵의학 검체검사에서의 영향

Purpose: At our hospital blood is collected from a patient before an imaging test, with the concern of any effect possible when a nuclear medicine imaging test and an in-vitro test are carried out at the same time. However, occasionally, the blood collection is performed after an imaging test, with the reasons that the patient is not properly guided or the patient doesn't follow the guide correctly. In that case, we prefer to gather blood again after a few days. The purpose of this study is not only to see whether there is any effect of an imaging test on the result of the in-vitro test performed with the blood collected after the imaging test, but also to study how many days waiting after each test is appropriate to take a blood sample, if the effect exists. Materials and Methods: From September to October 2013, blood were collected from 13 patients in our hospital regardless of age and sex each time before and after the injection of the radioactive isotope from the tests : PET-CT, Gated Myocardial SPECT, and DTPA GFR Scan. Considering a half-life, AFP, CA19-9, CEA, TSH, and T3 were carried out right after the blood collection. In case of an iodine therapy, blood were taken each time before and after taking radioactive iodine, and, after AFP, CA19-9, and CEA, the difference between them in consistency and in cpm were compared. Results: With 10 patients after the imaging tests and 3 patients after the iodine therapy, their serum cpm was over 10,000. Over time, the cpm decreased in accordance with the half-life ($^{18}F$ 110minutes, $^{99}mTc$ 6hours, $^{201}Tl$ 72hours, $^{131}I$ 7days). Between the two cases, one before and the other after the injection of the radioactive isotope, the cpm and the results of AFP, CA19-9, CEA, TSH, and T3 from three patients each test, PET-CT, Gated Myocardial SPECT, and DTPA GFR Scan, were very similar. In addition, in case of an iodine therapy, there was also not a meaningful difference in the cpm and the results of AFP, CA19-9, and CEA, from three patients in an iodine therapy, between the two cases, one before and the other after taking the radioactive iodine. Conclusion: In case a blood collection was performed after the imaging test which required a radioactive isotope injection, the cpm increased, differently according to the kind of the radioactive isotope. However, the results of the in-vitro tests like AFP, CA19-9, CEA, TSH, T3, etc were nearly not affected. As the result, it's considered that there will not be any significant effect also from other tests, as the result from the performed seven tests.

핵의학과 영상검사 후에 검체검사를 시행할 경우 결과값에 미치는 영향을 알아보기 위해 PET-CT, Gated Myocardial SPECT, DTPA GFR Scan을 시행하기 전 후에 채혈하여 Tumor marker (AFP,CEA,CA19-9), Hormone (TSH,T3,TG,TG Ab)검사를 시행하여 Difference를 구하였다. 대부분의 결과가 10% 이내의 차이를 나타냈지만 Table 7의 sample 2와 Table 8의 sample 1, sample 6, sample 8의 저 농도 값에서 20%를 넘는 차이를 나타내는 경우가 있었다. 그렇지만 cpm값은 Table 7의 sample 2는 984(전), 1057(후) Table 8의 sample 1은 243(전), 301(후) sample 6은 58(전), 64(후) sample 8은 258(전), 203(후)으로 매우 흡사한 값을 나타냈다. 이 같은 값을 바탕으로 볼 때 영상검사를 시행한 후에 검체검사를 시행하더라도 결과값에 미치는 영향은 없는 것으로 판단된다.