99m Technetium Pertechnetate Thyroid Scan for remnant thyroid tissue detection among post-thyroidectomy patients at Jose R. Reyes Memorial Medical Center: A retrospective analysis

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.