ABSTRACT
@#This study aims to determine the diagnostic value of a 99mTc-pertechnetate (99m TcO-4) thyroid scan among patients with DTC who underwent thyroidectomy to assess functioning thyroid remnants before radioactive iodine therapy. A retrospective non-experimental cross-sectional design was done to compare the results of the 99m TcO-4 thyroid scan with the patient's post-RAI scan. A review of all our patients' charts was done for eight years, and after excluding those that did not fit the criteria, 70 patients were included in the study. Data collected was analyzed on a "per patient" basis– where patients either had a "positive scan" or "negative scan", and on a "per lesion" basis – where every lesion's presence and size were compared on both modalities. 99m TcO-4 thyroid scan in the "per patient" analysis showed a sensitivity of 73.91%, specificity of 100%, positive predictive value (PPV) or 100%, and accuracy of 74.29%, however, negative predictive value was determined to be 5.26%. In the "per lesion" analysis, the scan had a less favorable performance with the computed sensitivity of 61.69%, PPV of 94.93%, and accuracy at 59.41%. It was then concluded that 99mTc-pertechnetate scan may be useful in determining functioning remnant thyroid tissue and subsequent management of DTC patients after thyroidectomy, but must take note of its low negative predictive value.
Subject(s)
Thyroid NeoplasmsABSTRACT
Introduction@#Radioactive Iodine therapy is an established therapeutic application of well-differentiated thyroid cancer. However, the proven benefits of ionizing radiation of Iodine-131 also carry potential toxicities to other normal exposed tissues. Good water hydration during the course of RAI therapy is one of the radiation protection measures to minimize toxicities, directed to increase excretion of unbound iodine from the body. Apparently, a number of recognized medical societies had different recommendations on the amount of water intake during radioactive iodine therapy.@*Objective@#To determine if there is a significant difference in the decrease of exposure rate, total effective dose equivalent, and length of stay of differentiated thyroid cancer patients undergoing high dose RAI when comparing between different amounts of water intake per day (<3L/day vs > 3 L/day).@*Methods@#This study employed a prospective cohort design. Patients with differentiated thyroid cancer (DTC) admitted for high-dose RAI therapy at Jose R. Reyes Memorial Medical Center were included in the study. Dose rate and water intake volume were measured and total effective dose equivalent was computed every 24-hrs until discharged. Student t test was used to compare two water intake levels on quantitative variables while fisher exact test for categorical data.@*Results@#A total of 47 participants were included in the study with 28 patients under > 3L/day group and 19 patients under < 3L/day with a mean consumption of 4.9 L/day and 2.3 L/day, respectively. There was no significant difference on the mean exposure rate between those who consumed at least 3L (15.3 mR/hr) against those who consumed less than 3L (17.3 mR/hr) during the time of intake, after the 24 hours (p=.9935) and 48 hours (p=.7523). Likewise, there is no significant difference on their mean total effective dose equivalent [in per day during intake (p=.9678), 24 hours (p=.4141) and 48 hours (p=.6706)]. The mean length of hospital stay is also the same for both groups with 1.7 days.@*Conclusion@#The study concludes that consuming different volume of water per day (> 3 L/day vs < 3L/ day) have the same rate of decreased in exposure rate, total effective dose equivalent (TEDE) as well as the same length of hospital