A prospective study of two PET/CT tracers found similar lesion detection in radioiodine-refractory differentiated thyroid cancer, although FDG showed higher uptake overall. The comparison was conducted in patients who underwent both scans.
Among 125 identified lesions, FDG detected 92.8%, compared with 89.6% for Pentixafor. The reported difference was not statistically significant, with a P value of 0.289.
A direct comparison in the same patients
The researchers set out to assess whether [68Ga]Ga-pentixafor PET/CT could provide diagnostic performance comparable to [18F]FDG PET/CT, and whether PET uptake parameters were associated with clinicopathological characteristics.
Nineteen patients were analyzed, with a median age of 60, and 125 lesions were identified. Participants were prospectively enrolled and underwent both scans within two weeks, putting the two tracers side by side within each participant.
Images were assessed visually and through semi-quantitative analysis. The researchers recorded lesion number, location and uptake parameters, then compared tracer performance and examined correlations with clinicopathological characteristics.
Lower overall uptake, but not in every lesion
The clearest difference appeared in the study's three reported uptake measures. Median SUVmax was 7.33 with FDG and 3.03 with Pentixafor. Median TBR was 9.04 versus 3.11, and median TMR was 4.88 versus 1.96. All three comparisons had reported P values below 0.001.
That overall pattern did not apply to every lesion. Among the 118 lesions detected by at least one tracer, 37, or 31.4%, had higher Pentixafor uptake than FDG. The accompanying median SUVmax values were 4.10 and 2.63.
TMR remains an exploratory marker
One of the measures, TMR, is the tumor-to-bone marrow ratio. Among Pentixafor-positive confirmed lesions, 72.3% had a TMR above 1, while 31.3% had a TMR above 2.
The analysis found no significant associations between PET uptake parameters and clinicopathological characteristics.
The authors suggest that TMR could serve as an exploratory imaging marker for selecting patients for CXCR4-targeted therapy, but say it requires validation. The result is a research lead, not an established treatment-selection rule.
A preliminary signal that needs testing
The study's scale calls for caution. It analyzed 19 patients, and its lesion-level figures draw on different groups: 125 identified lesions for the detection comparison and 118 lesions detected by at least one tracer for the higher-Pentixafor analysis. The percentages therefore do not all describe exactly the same set of lesions.
The authors interpret Pentixafor as having similar lesion detection to FDG in this cohort despite lower overall uptake, while presenting TMR as an exploratory marker that still needs clinical validation for CXCR4-targeted therapy selection.
Publication and study disclosures
The peer-reviewed article was published on 21 August 2026. It reports that the study followed the Declaration of Helsinki, received institutional ethics approval and was registered with the Chinese Clinical Trial Registry under ChiCTR2400084339. Written informed consent was obtained from all participants.
The research was supported by the Science & Technology Department of Sichuan Province and the National Natural Science Foundation of China. The authors reported no relevant financial or non-financial competing interests. The datasets are not publicly available because of patient privacy and ethical restrictions, but can be requested from the corresponding author.
Paper data and sources
Original title: Exploration of Chemokine Receptor 4 Targeted [Ga]Ga-pentixafor PET/CT in Radioiodine-refractory Differentiated Thyroid Cancer.
Authors: Yanlin Liu, Hongyuan Dai, Chenyu Sun et al.
Journal/Repository: Molecular imaging and biology
Status: Peer-reviewed
First online: 2026-08-21
DOI: 10.1007/s11307-026-02129-1
Original paper · Full text