A Multicenter Clinical Trial on the Diagnostic Value of Dual-Tracer PET/CT in Pulmonary Lesions Using 3′-Deoxy-3′-¹⁸F-Fluorothymidine and ¹⁸F-FDG

Abstract

Some new radiotracers might add useful information and improve diagnostic confidence of 18 F-FDG imaging in tumors. A multicenter clinical trial was designed to investigate the diagnostic performance of dual-tracer ( 18 F-FDG and 39-deoxy-39-18 F-fluorothymidine [ 18 F-FLT]) PET/CT in pulmonary nodules. Methods: Fifty-five patients underwent dual-tracer imaging in 6 imaging centers using the same models of equipment and standardized protocols. The images were interpreted by a collective group of readers who were unaware of the clinical data. The diagnostic performance using either tracer alone or dual-tracers together, with or without CT, was compared. The histological diagnosis or clinical findings in a 12-mo follow-up period served as the standard of truth. Results: In 16 patients with malignant tumor, 16 with tuberculosis, and 23 with other benign lesions, the sensitivity and specificity of 18 F-FDG and 18 F-FLT were 87.5% and 58.97% and 68.75% and 76.92%, respectively. The combination of dual-tracer PET/CT improved the sensitivity and specificity up to 100% and 89.74%. The 3 subgroups of patients could be best separated when the 18 F-FLT/ 18 F-FDG standardized uptake value ratio of 0.4-0.90 was used as the threshold. Conclusion: By reflecting different biologic features, the dualtracer PET/CT using 18 F-FDG and 18 F-FLT favorably affected the diagnosis of lung nodules.

Role of Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Imaging in Diagnosis and Staging of Lung Cancer

“…FLT'nin malign lezyonlar için özgüllüğü FDG'ye göre daha yüksek olmakla birlikte, sadece S-fazındaki hücrelerde tutulum göstermesi nedeniyle tümördeki FLT tutulumu FDG'ye göre düşüktür (73). Bu nedenle akciğer kanserinde hem primer tümörün hem de lenf nodu metastazlarının gösterilmesinde duyarlılığı FDG PET/ BT görüntülemeye göre daha düşüktür (74,75). FLT PET görüntülemenin öncelikli kullanım alanı tedaviye yanıtın değerlendirilmesidir.…”

Dual Tracer PET Imaging with FDG and FLT Differentiates Tuberculous Lymphadenopathy from Metastases in a Case of Carcinoma Cervix

“…Hence, a tracer that is more specific marker for malignancy can help to identify false-positive FDG PET findings. Use of dual tracer imaging with FDG and FLT to differentiate between benign and malignant lesions has been described in the literature for characterization of pulmonary lesions [3]. FLT is thought to be relatively more specific compared to 18F-FDG, in that it is a cell proliferation tracer; FLT usually does not concentrate in benign lesions [4].…”

Navigating beyond the 6th dimension: a challenge in the era of multi-parametric molecular imaging

“…With the highly sophisticated technologies available today, navigating beyond the fifth dimension in vivo is becoming feasible by incorporating cardiac or respiratory gating or both [25], CT or MR contrast agent dynamics or alternatively multitracer PET studies [26,27] probing other biological or physiological processes (e.g. tumour hypoxia in oncological imaging).…”

“…99m Tc-HMPAO) are combined to record and differentiate through energy discrimination the two signals. Another more interesting and also more technically challenging approach would be to exploit recent developments in multitracer PET studies targeting different physiological or biological processes [26,27], where two to three PET probes, e.g. 18 F-FDG and 18 F-EF5 [32], are injected either sequentially or simultaneously to allow imaging tumour glucose metabolism and tumour hypoxia, respectively.…”

“…18 F-FDG for glucose metabolism and 18 F-FLT for tumour cell proliferation) is already performed routinely in some centres [27], simultaneous dual-tracer imaging using PET is very complicated to achieve and still is an immature field. The possibility of fast scanning of multiple PET probes using a well-designed dynamic imaging protocol allowing one to extract the signal of each probe based upon inherent differentiation between radionuclides' half-lives, tracer kinetics and biodistribution has been reported recently [33,34].…”