Marcus Unterrainer1, Norbert Galldiks2,3, Bogdana Suchorska4, Lara-Caroline Kowalew1, Vera Wenter1, Christine Schmid-Tannwald5, Maximilian Niyazi6,7, Peter Bartenstein1, Karl-Josef Langen2,8,9, Nathalie L Albert10. 1. Department of Nuclear Medicine, University of Munich (LMU), Munich, Germany. 2. Institute of Neuroscience and Medicine, Research Center Juelich, Juelich, Germany. 3. Department of Neurology, University Hospital Cologne, Cologne, Germany. 4. Department of Neurosurgery, LMU, Munich, Germany. 5. Institute for Clinical Radiology, LMU, Munich, Germany. 6. Department of Radiation Oncology, LMU, Munich, Germany. 7. German Cancer Consortium (DKTK) & German Cancer Research Center (DKFZ), Heidelberg, Germany. 8. Department of Nuclear Medicine, University of Aachen, Aachen, Germany; and. 9. JARA-Brain Section, Juelich-Aachen-Research-Alliance (JARA), Juelich, Germany. 10. Department of Nuclear Medicine, University of Munich (LMU), Munich, Germany nathalie.albert@med.uni-muenchen.de.
Abstract
In patients with brain metastasis, PET using labeled amino acids has gained clinical importance, mainly regarding the differentiation of viable tumor tissue from treatment-related effects. However, there is still limited knowledge concerning the uptake characteristics in patients with newly diagnosed and untreated brain metastases. Hence, we evaluated the uptake characteristics in these patients using dynamic O-(2-18F-fluoroethyl)-l-tyrosine (18F-FET) PET. Methods: Patients with newly diagnosed brain metastases without prior local therapy and 18F-FET PET scanning were retrospectively identified in 2 centers. Static and dynamic PET parameters (maximal/mean tumor-to-brain-ratio [TBRmax/TBRmean], biologic tumor volume [BTV], and time-activity curves with minimal time to peak [TTPmin]) were evaluated and correlated with MRI parameters (maximal lesion diameter, volume of contrast enhancement) and originating primary tumor. Results: Forty-five brain metastases in 30 patients were included. Forty of 45 metastases (89%) had a TBRmax ≥ 1.6 and were classified as 18F-FET-positive (median TBRmax, 2.53 [range, 1.64-9.47]; TBRmean, 1.86 [range, 1.63-5.48]; and BTV, 3.59 mL [range, 0.04-23.98 mL], respectively). In 39 of 45 brain metastases eligible for dynamic analysis, a wide range of TTPmin was observed (median, 22.5 min; range, 4.5-47.5 min). All 18F-FET-negative metastases had a diameter of ≤ 1.0 cm, whereas metastases with a > 1.0 cm diameter all showed pathologic 18F-FET uptake, which did not correlate with lesion size. The highest variability of uptake intensity was observed within the group of melanoma metastases. Conclusion: Untreated metastases predominantly show increased 18F-FET uptake, and only a third of metastases < 1.0 cm were 18F-FET-negative, most likely because of scanner resolution and partial-volume effects. In metastases > 1.0 cm, 18F-FET uptake intensity was highly variable and independent of tumor size (even intraindividually). 18F-FET PET might provide additional information beyond the tumor extent by reflecting molecular features of a metastasis and might be a useful tool for future clinical applications, for example, response assessment.
In patients with brain metastasis, PET using labeled amino acids has gained clinical importance, mainly regarding the differentiation of viable tumor tissue from treatment-related effects. However, there is still limited knowledge concerning the uptake characteristics in patients with newly diagnosed and untreated brain metastases. Hence, we evaluated the uptake characteristics in these patients using dynamic O-(2-18F-fluoroethyl)-l-tyrosine (18F-FET) PET. Methods:Patients with newly diagnosed brain metastases without prior local therapy and 18F-FET PET scanning were retrospectively identified in 2 centers. Static and dynamic PET parameters (maximal/mean tumor-to-brain-ratio [TBRmax/TBRmean], biologic tumor volume [BTV], and time-activity curves with minimal time to peak [TTPmin]) were evaluated and correlated with MRI parameters (maximal lesion diameter, volume of contrast enhancement) and originating primary tumor. Results: Forty-five brain metastases in 30 patients were included. Forty of 45 metastases (89%) had a TBRmax ≥ 1.6 and were classified as 18F-FET-positive (median TBRmax, 2.53 [range, 1.64-9.47]; TBRmean, 1.86 [range, 1.63-5.48]; and BTV, 3.59 mL [range, 0.04-23.98 mL], respectively). In 39 of 45 brain metastases eligible for dynamic analysis, a wide range of TTPmin was observed (median, 22.5 min; range, 4.5-47.5 min). All 18F-FET-negative metastases had a diameter of ≤ 1.0 cm, whereas metastases with a > 1.0 cm diameter all showed pathologic 18F-FET uptake, which did not correlate with lesion size. The highest variability of uptake intensity was observed within the group of melanoma metastases. Conclusion: Untreated metastases predominantly show increased 18F-FET uptake, and only a third of metastases < 1.0 cm were 18F-FET-negative, most likely because of scanner resolution and partial-volume effects. In metastases > 1.0 cm, 18F-FET uptake intensity was highly variable and independent of tumor size (even intraindividually). 18F-FET PET might provide additional information beyond the tumor extent by reflecting molecular features of a metastasis and might be a useful tool for future clinical applications, for example, response assessment.
Authors: Norbert Galldiks; Karl-Josef Langen; Nathalie L Albert; Marc Chamberlain; Riccardo Soffietti; Michelle M Kim; Ian Law; Emilie Le Rhun; Susan Chang; Julian Schwarting; Stephanie E Combs; Matthias Preusser; Peter Forsyth; Whitney Pope; Michael Weller; Jörg C Tonn Journal: Neuro Oncol Date: 2019-05-06 Impact factor: 12.300
Authors: Knut Johannessen; Erik Magnus Berntsen; Håkon Johansen; Tora S Solheim; Anna Karlberg; Live Eikenes Journal: Eur J Hybrid Imaging Date: 2021-04-13