False-positive I-131 Scan by Contaminated Muffler in a Patient with Thyroid Carcinoma / 핵의학분자영상

A 39-year-old female patient who had undergone a total thyroidectomy for a papillary thyroid carcinoma underwent a whole body scan with I-131. The I-131 scan was performed 72 hours after administering 185 MBq (5 mCi) of an I-131 solution. The anterior image of the head, neck, and upper chest showed multiple areas of increased uptake in the mediastinal area considering of functional metastasis. However, radioactivity was not evident in the image taken after removing her clothes and muffler. The image obtained after placing the muffler on the pallet showed that the radioactivity was still present. It is well known that artifacts on an I-131 scan can be produced by styling hair sputum, drooling during sleep, chewing gum, and paper or a cloth handkerchief that is contaminated with the radioactive iodine from either perspiration or saliva. This activity might be mistaken for a functional metastasis. Therefore, it is essential that an image be obtained after removing the patient's clothes. In this study, artifacts due to a contaminated muffler on the I-131 scan were found. These mimicked a functional metastasis of the mediastinal area in a patient with a papillary thyroid carcinoma.

An Artifact Caused by Using the Inadequate Acquisition Parameter in Tc-99m ECD Brain Perfusion SPECT / 대한핵의학회잡지

Although artifacts in tomographic imaging can arise from a number of sources, this case presents an artifact caused by using inadequate acquisition parameters which do not match the collimator with which a camera equipped in Tc-99m ECD brain SPECT. Whenever the collimator in tomographic studies is changed, we should take care to use suitable parameters of acquisition protocol according to the collimator with which a camera is fitted. Other ways to prevent an error of this type is to use a point source.

The Evaluation of Factors Which Influence Binding Efficiency of Modified in Vivo Erythrocyte Labeling Technique / 대한핵의학회잡지

PURPOSE: We underwent this study to evaluate the factors which influence labeling efifciency when modified in vivo erythrocyte labeling technique was used. MATERIALS AND METHODS: Thirty healthy volunteers (M: F=19: 11, age: 25 +/- 2 yrs) were enrolled in this study. Totally, two hundred ten samples were obtained from them. The 1 mg of stannous pyrophosphate was injected intravenously at the beginning of labeling. After suitable tinning time (5 min, 20 min, 35 min) passed by, blood (5 mL, 3 mL or 1 mL) was withdrawn into 10 mL syringe previously containing Tc-99m (740 MBq) and anticoagulant (heparin, ACD or CPDA) through 19-gauged scalp needle. The generator ingrowth time of Tc-99m was within 24 hrs in each case. The blood samples were placed on rotating invertor during incubation (10 min, 25 min, 40 min) but some of them were not. Immediately after the conclusion of incubation, the labeled blood specimens to analyze were centrifuged. and then %Unbound Tc-99m was calculated. Statical analysis was used paired T-test and one way ANOVA with SPSS 10.0. RESULTS: The binding efficiency at 1 mL of blood volume was 73 +/- 32%, 91 +/- 10% at 3 mL and 96 +/- 7% at 5 mL (p 0.05). The binding efficiency in case of using rotating invertor was 96 +/- 7% and the binding efficiency in case of not using it was 87 +/- 18% (p> 0.05). There was no significant difference between them. In binding efficiency according to kinds of anticoagulants, ACD was 98 +/- 4%, CPDA was 97 +/- 6% and heparin was 89 +/- 20% (p< 0.001). CONCLUSION: When modified in vivo erythrocyte labeling technique is used with Tc-99m, the methods to obtain the highest labeling efficiency are as follow. The withdrawing blood volume should be over 3 mL, tinning time should be kept between 20 min and 35 min, and incubation time should be kept between 10 min and 40 min. ACD or CPDA have to be used as a anticoagulant except heparin and the blood samples should be placed on rotating invertor during incubation.