RT Journal Article
SR Electronic
T1 SPECT/US and PET/US Fusion Imaging of the Thyroid
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 52
OP 52
VO 61
IS supplement 1
A1 Seifert, Philipp
A1 Winkens, Thomas
A1 Kuehnel, Christian
A1 Freesmeyer, Martin
YR 2020
UL http://jnm.snmjournals.org/content/61/supplement_1/52.abstract
AB 52Background: Conventional diagnostics (CD) of thyroid nodules (TN) comprises ultrasound (US) and scintigraphy scans. Combining these two modalities can lead to uncertain or incorrect topographic assignments. Hybrid imaging is an established and successful solution for many issues in nuclear medicine. However, research data on SPECT/US and PET/US fusion imaging of the thyroid are scarce. The present data firstly represent the value of fusion imaging in the field of TN diagnostics on the basis of a considerable number of patients and observers. Methods: Between 2015 and 2017, 700 consecutive patients have been referred to our clinic for CD of TN. In case of uncertainties, additional 99m-technetium-SPECT/US and 124-iodine-PET/US fusion imaging has been performed. The institutional review board approved the prospective study design and the study has been registered at clinicaltrials.gov (NCT03 128 255). Three experienced institutional experts compared the overall performance of CD, SPECT/US and PET/US. The investigators subsequently decided whether the uncertainty arising from CD could be solved by SPECT/US and PET/US. Furthermore, a lesion-by-lesion based functional assessment of the TN (hyperfunctioning, hypofunctioning, indifferent) containing their confidence in rating (nominal 4-point scale) was carried out.Representative digital patient case files (PCF) have been created for a multicentre and multiobserver study. Two corresponding PCF per patient have been prepared, containing either CDonly or CD+PET/US. The independent observers rated at least 4 randomly assigned PCF regarding the TN function (hyperfunctioning, hypofunctioning, indifferent, not rateable) their confidence in functional assessment (nominal 5-point scale) and their suggestion of treatment. In 70 patients, 201 TN were included. PET/US was superior to CD and SPECT/US in 96% and 86%, respectively. SPECT/US was superior to CD in 84%. Using SPECT/US fusion images, 67% of the uncertainties on CD could be solved, whereas PET/US enabled the investigators to clarify the equivocal CD findings in nearly all cases (96%). 10 (66%), 39 (14%) and 71% (4%) of the 201 lesions were rated with absolute certainty (equivocal or uncertain) in CD, SPECT/US and PET/US, respectively (p<0.001).Out of the 70 patients, 68 PCF of 34 patients, comprising 66 TN ≥1cm were selected. 106 observers recorded a total of 748 (11.2/TN) and 751 ratings (11.4/TN) for CDonly and CD+PET/US, respectively. The functional assessment showed more hyper- or hypofunctioning (524 vs. 320, p<0.0001) and less indifferent or not rateable (209 vs. 428, p<0.0001) TN in CD+PET/US vs. CDonly. The observers’ confidence in functional assessment was superior in CD+PET/US (p<0.0001). Fewer suggestion of follow up (p<0.0001), and more (p<0.0001) suggestion of invasive treatments (fine-needle aspiration & surgery) was observed in CD+PET/US. Radioiodine therapy was more often (p=0.0036), and thyroid medication less often (p=0.0167) advised in CD+PET/US.Conclusions: Both SPECT/US and PET/US fusion imaging proofed feasible and helpful as problem solving tools for equivocal findings on CD of TN. CD frequently shows failures in functional assessment of TN, underestimating the incidence of hyper- and hypofunctioning lesions. Confidence in functional assessment significantly increases by using additional fusion imaging approaches, especially PET/US.