Head-to-Head Comparison of Neck 18F-FDG PET/MR and PET/CT in the Diagnosis of Differentiated Thyroid Carcinoma Patients after Comprehensive Treatment

Abstract

We explored the clinical value of 18F-FDG PET/MR in a head-to-head comparison with PET/CT in loco-regional recurrent and metastatic cervical lymph nodes of differentiated thyroid carcinoma (DTC) patients after comprehensive treatment. 18F-FDG PET/CT and neck PET/MR scans that were performed in DTC patients with suspected recurrence or cervical lymph node metastasis after comprehensive treatment were retrospectively analyzed. Detection rates, diagnostic efficacy, image conspicuity, and measured parameters were compared between 18F-FDG PET/CT and PET/MR. The gold standard was histopathological diagnosis or clinical and imaging follow-up results for more than 6 months. Among the 37 patients enrolled, no suspicious signs of tumor were found in 10 patients, 24 patients had lymph node metastasis, and 3 patients had both recurrence and lymph node metastases. A total of 130 lesions were analyzed, including 3 malignant and 6 benign thyroid nodules, as well as 74 malignant and 47 benign cervical lymph nodes. Compared with PET/CT, PET/MR presented better detection rates (91.5% vs. 80.8%), image conspicuity (2.74 ± 0.60 vs. 1.9 ± 0.50, p < 0.001, especially in complex level II), and sensitivity (80.5% vs. 61.0%). SUVmax differed in benign and malignant lymph nodes in both imaging modalities (p < 0.05). For the same lesion, the SUVmax, SUVmean, and diameters measured by PET/MR and PET/CT were consistent and had significant correlation. In conclusion, compared with 18F-FDG PET/CT, PET/MR was more accurate in determining recurrent and metastatic lesions, both from a patient-based and from a lesion-based perspective. Adding local PET/MR after whole-body PET/CT may be recommended to provide more precise diagnostic information and scope of surgical resection without additional ionizing radiation. Further scaling-up prospective studies and economic benefit analysis are expected.

Intra-Individual Comparison of 124I-PET/CT and 124I-PET/MR Hybrid Imaging of Patients with Resected Differentiated Thyroid Carcinoma: Aspects of Attenuation Correction

“…The measured differences in lesion activity quantification of congruent lesions are in the range that was reported for previous single-administration dual hybrid imaging studies with PET/CT and PET/MR [11,32]. Such differences result from multiple methodological factors and challenges that are inherent to single-administration sequential PET studies on different PET systems [10] as discussed above. Our results support the examination of patients with differentiated thyroid carcinoma after thyroidectomy with any of the two-hybrid imaging modalities, 124 I-PET/CT or 124 I-PET/MR.…”

“…PET/MR imaging inherently offers improved soft-tissue contrast and additional functional imaging parameters (e.g., diffusion-weighted imaging, DWI) compared to PET/CT imaging. For the detection and staging of differentiated thyroid carcinoma (DTC) both hybrid imaging modalities, PET/CT and PET/MR, have been used with radiotracers 124 Iodine-NaI ( 124 I) or fluoro-18-fluorodeoxyglucose ( 18 F-FDG) [6][7][8][9][10][11]. The high sensitivity of the PET component combined with the superior ability of MR to detect small lesions in the head/neck region may result in improved diagnostics, therapy monitoring and 124 I dosimetry of thyroid cancer compared with PET/CT [9][10][11].…”

“…For the detection and staging of differentiated thyroid carcinoma (DTC) both hybrid imaging modalities, PET/CT and PET/MR, have been used with radiotracers 124 Iodine-NaI ( 124 I) or fluoro-18-fluorodeoxyglucose ( 18 F-FDG) [6][7][8][9][10][11]. The high sensitivity of the PET component combined with the superior ability of MR to detect small lesions in the head/neck region may result in improved diagnostics, therapy monitoring and 124 I dosimetry of thyroid cancer compared with PET/CT [9][10][11]. PET/CT and PET/MR examinations are performed differently with regard to patient positioning and acquisition times and require fundamentally different attenuation correction (AC) methods.…”

Prognostic Value of Hybrid PET/MR Imaging in Patients with Differentiated Thyroid Cancer

“…Song et al [ 16 ] explored the clinical value of 18 F-FDG PET/MR in a head-to-head comparison with PET/CT in loco-regional recurrent and metastatic cervical lymph nodes of DTC patients after comprehensive treatment. Compared with PET/CT, PET/MR showed better detection rates, and higher diagnostic sensitivity and accuracy.…”

“…Such a tool also has the potential to improve the information content of one modality with the other and offers new opportunities in patients with DTC [ 15 ]. Initial attempts to use PET/MR imaging in the evaluation of DTC patients have recently been carried out [ 16 , 17 , 18 ]. The aim of this study was to retrospectively evaluate the prognostic value of hybrid 18 F-FDG PET/MR in patients who had already underwent total thyroidectomy and RAI therapy for DTC with suspicion of disease relapse.…”