Project description:BackgroundTo evaluate the impact of respiratory-averaged computed tomography attenuation correction (RACTAC) compared to standard single-phase computed tomography attenuation correction (CTAC) map, on the quantitative measures of coronary atherosclerotic lesions of 18F-sodium fluoride (18F-NaF) uptake in hybrid positron emission tomography and computed tomography (PET/CT).MethodsThis study comprised 23 patients who underwent 18F-NaF coronary PET in a hybrid PET/CT system. All patients had a standard single-phase CTAC obtained during free-breathing and a 4D cine-CT scan. From the cine-CT acquisition, RACTAC maps were obtained by averaging all images acquired over 5 seconds. PET reconstructions using either CTAC or RACTAC were compared. The quantitative impact of employing RACTAC was assessed using maximum target-to-background (TBRMAX) and coronary microcalcification activity (CMA). Statistical differences were analyzed using reproducibility coefficients and Bland-Altman plots.ResultsIn 23 patients, we evaluated 34 coronary lesions using CTAC and RACTAC reconstructions. There was good agreement between CTAC and RACTAC for TBRMAX (median [Interquartile range]): CTAC = 1.65 [1.23 to 2.38], RACTAC = 1.63 [1.23 to 2.33], p = 0.55), with coefficient of reproducibility of 0.18, and CMA: CTAC = 0.10 [0 to 1.0], RACTAC = 0.15 [0 to 1.03], p = 0.55 with coefficient of reproducibility of 0.17 CONCLUSION: Respiratory-averaged and standard single-phase attenuation correction maps provide similar and reproducible methods of quantifying coronary 18F-NaF uptake on PET/CT.
Project description:PurposeThis study aimed to assess the diagnostic performance of [18F]FAPI-42 PET/CT and compare it with that of 2-[18F]FDG PET/CT in patients with differentiated thyroid cancer (DTC) with biochemical elevations in Tg or anti-Tg antibodies.MethodsA total of 42 patients with DTC with biochemical elevations in Tg or anti-Tg antibodies underwent [18F]FAPI-42 PET/CT as part of this study; of which, 11 additionally underwent 2-[18F]FDG PET/CT within 7 days. Images were semi-quantitatively and visually interpreted, and the quantity, location, and uptake values of lesions were noted. The diagnostic capacity of [18F]FAPI-42 PET/CT and biomarkers affecting the uptake of [18F]FAPI-42 were evaluated. In addition, the diagnostic performance and uptake of [18F]FAPI-42 and 2-[18F]FDG were compared, and the correlation between lesion diameter and quantitative parameters was investigated.ResultsA total of 161 lesions were detected in 27 (64%) patients on [18F]FAPI-42 PET/CT. FAPI-positive local recurrence showed the highest uptake intensity, followed by lymphatic, other site-associated (bone and pleura), and pulmonary lesions (mean SUVmax, 4.7 versus 3.7 versus 3.0 versus 2.2, respectively; P < 0.0001). The levels of TSH, Tg, and Tg-Ab did not affect the uptake value of lesions (median SUVmax: 2.4 versus 3.2, P = 0.56; 2.9 versus 2.4, P = 0.0935; 2.8 versus 2.6, P = 0.0525, respectively). A total of 90 positive lesions were detected in 7 patients using both modalities. All positive lesions showed statistically higher uptake of 2-[18F]FDG than that of [18F]FAPI-42 (SUVmax, 2.6 versus 2.1; P = 0.026). However, the SUVmax of [18F]FAPI-42 was higher than that of 2-[18F]FDG in local recurrences and lymphatic lesions (SUVmax, 4.2 versus 2.9 and 3.9 versus 3.4, respectively; P > 0.05).Conclusion[18F]FAPI-42 can be used for detecting lesions and reflecting FAP expression during local recurrence and metastasis in patients with DTC with biochemical elevations in Tg or anti-Tg antibodies. The diagnostic performance of [18F]FAPI-42 PET/CT is comparable with that of 2-[18F]FDG PET/CT in such patients.
Project description:BackgroundStandard of care metabolic bone disease assessment relies on changes to bone quantity, which can only be detected after structural changes occur.PurposeTo investigate the usefulness of Bone Metabolism Score (BMS), derived from fluorine 18 labeled sodium fluoride (18F-NaF) PET/CT imaging as a biomarker of localized metabolic changes at the femoral neck.MethodsIn this retrospective study, 139 participants (68 females and 71 males, ages 21-75 years) that had undergone 18F-NaF PET/CT were included. BMS was calculated as the ratio of standard uptake value (SUV) in the bone region to that of the total region. Correlations and linear regressions of BMS with age, CT-derived bone mineral density (BMD), body mass index (BMI), height, and weight were conducted. Differences in BMS between women younger and older than the age of 50 years were assessed. Inter- and intra-operator reproducibility was evaluated by coefficient of variation (CV) and intra-class correlation coefficient (ICC).ResultsAmong females, age was negatively correlated with left and right whole BMS (5.61% and 4.90% drop in BMS per decade of life) and left and right cortical BMS (10.50% and 10.09% drop in BMS per decade of life). BMS of women older than 50 years was lower than BMS of women younger than 50 years (P < .0001). Among males, age was negatively correlated with left and right whole BMS (4.29% and 4.25% drop in BMS per decade of life) and left and right cortical BMS (9.13% and 10.30% drop in BMS per decade of life). BMD was positively correlated with whole (r = 0.80, P < .0001) and cortical (r = 0.92, P < .0001) BMS.ConclusionsBMS could provide functional insight regarding bone metabolism in the femoral neck to complement bone health status assessed through conventional structural imaging. The methodology described herein could be potentially useful for assessing hip fracture risk in individuals when BMD tests provide borderline determination of bone disease.
Project description:Accurate measurement of glomerular filtration rate (GFR) is essential for optimal decision making in many clinical settings of renal failure. We aimed to show that GFR can be accurately measured using compartmental tracer kinetic analysis of 18F-fluoride dynamic PET/CT. Twenty-three male Sprague-Dawley rats of three experimental groups (cyclosporine-administered [n = 8], unilaterally nephrectomized [n = 8], and control [n = 7]) underwent simultaneous 18F-fluoride dynamic PET/CT and reference 51Cr-EDTA GFR (GFRCrEDTA) test at day 0 and post-intervention day 3. 18F-fluoride PET GFR (GFRF-PET) was calculated by multiplying the influx rate and functional kidney volume in a single-tissue-compartmental kinetic model. Within-test repeatability and between-test agreement were evaluated by intraclass correlation coefficient (ICC) and Bland-Altman analysis. In the control group, repeatability of GFRF-PET was excellent (ICC = 0.9901, repeatability coefficient = 12.5%). GFRF-PET significantly decreased in the renally impaired rats in accordance with respective GFRCrEDTA changes. In the pooled population, GFRF-PET agreed well with GFRCrEDTA with minimal bias (-2.4%) and narrow 95% limits of agreement (-25.0% to 20.1%). These data suggest that the single-compartmental kinetic analysis of 18F-fluoride dynamic PET/CT is an accurate method for GFR measurement. Further studies in humans are warranted.
Project description:Our purpose was to establish whether noninvasive measurement of changes in 18F-fluoride metabolic flux to bone mineral (Ki) by PET/CT can provide incremental value in response assessment of bone metastases in breast cancer compared with SUVmax and SUVmean Methods: Twelve breast cancer patients starting endocrine treatment for de novo or progressive bone metastases were included. Static 18F-fluoride PET/CT scans were acquired 60 min after injection, before and 8 wk after commencing treatment. Venous blood samples were taken at 55 and 85 min after injection to measure plasma 18F-fluoride activity concentrations, and Ki in individual bone metastases was calculated using a previously validated method. Percentage changes in Ki, SUVmax, and SUVmean were calculated from the same index lesions (≤5 lesions) from each patient. Clinical response up to 24 wk, assessed in consensus by 2 experienced oncologists masked to PET imaging findings, was used as a reference standard. Results: Of the 4 patients with clinically progressive disease (PD), mean Ki significantly increased (>25%) in all, SUVmax in 3, and SUVmean in 2. Of the 8 non-PD patients, Ki decreased or remained stable in 7, SUVmax in 5, and SUVmean in 6. A significant mean percentage increase from baseline for Ki, compared with SUVmax and SUVmean, occurred in the 4 patients with PD (89.7% vs. 41.8% and 43.5%, respectively; P < 0.001). Conclusion: After 8 wk of endocrine treatment for bone-predominant metastatic breast cancer, Ki more reliably differentiated PD from non-PD than did SUVmax and SUVmean, probably because measurement of SUV underestimates fluoride clearance by not considering changes in input function.
Project description:BackgroundThe lack of visualization of the spinal cord hinders the evaluation of [18F]Fluoro-deoxy-glucose (FDG) uptake of the spinal cord in PET/CT. By exploiting the capability of MRI to precisely outline the spinal cord, we performed a retrospective study aimed to define normal pattern of spinal cord [18F]FDG uptake in PET/MRI.MethodsForty-one patients with lymphoma without clinical or MRI signs of spinal cord or bone marrow involvement underwent simultaneous PET and MRI acquisition using Siemens Biograph mMR after injection of 3.5 MBq/kg body weight of [18F]FDG for staging purposes. Using a custom-made software, we placed ROIs of 3 and 9 mm in diameter in the spinal cord, lumbar CSF, and vertebral marrow that were identified on MRI at 5 levels (C2, C5, T6, T12, and L3). The SUVmax, SUVmean, and the SUVmax and SUVmean normalized (NSUVmax and NSUVmean) to the liver were measured. For comparison, the same ROIs were placed in PET-CT images obtained immediately before the PET-MRI acquisition following the same tracer injection.ResultsOn PET/MRI using the 3 mm ROI, the following average (all level excluding L3) spinal cord median (1st and 3rd quartile) values were measured: SUVmean, 1.68 (1.39 and 1.83); SUVmax, 1.92 (1.60 and 2.14); NSUVmean, 1.18 (0.93 and 1.36); and NSUVmax, 1.27 (1.01 and 1.33). Using the 9 mm ROI, the corresponding values were SUVmean, 1.41 (1.25-1.55); SUVmax, 2.41 (2.08 and 2.61); NSUVmean, 0.93 (0.79 and 1.04); and NSUVmax, 1.28 (1.02 and 1.39). Using the 3 mm ROI, the highest values of PET-MRI SUVmax, SUVmean, NSUVmax, and NSUVmean were consistently observed at C5 and the lowest at T6. Using a 9 mm ROI, the highest values were consistently observed at C5 and the lowest at T12 or T6. The spinal cord [18F]FDG-uptake values correlated with the bone marrow uptake at the same level, especially in case of NSUVmax. Comparison with PET-CT data revealed that the average SUVmax and SUVmean of the spinal cord were similar in PET-MRI and PET-CT. However, the average NSUVmax and NSUVmean of the spinal cord were higher (range 21-47%) in PET-MRI than in PET-CT.ConclusionsUsing a whole-body protocol, we defined the maximum and mean [18F]FDG uptake of the normal spinal cord in PET/MRI. While the observed values show the expected longitudinal distribution, they appear to be higher than those measured in PET/CT. Normalization of the SUVmax and SUVmean of the spinal cord to the liver radiotracer uptake could help in multi-institutional comparisons and studies.
Project description:BackgroundThe diagnostic performance of 18F-sodium fluoride positron emission tomography/computed tomography (PET/CT) (NaF), 18F-fluorocholine PET/CT (FCH) and diffusion-weighted whole-body magnetic resonance imaging (DW-MRI) in detecting bone metastases in prostate cancer (PCa) patients with first biochemical recurrence (BCR) has already been published, but their cost-effectiveness in this indication have never been compared.MethodsWe performed trial-based and model-based economic evaluations. In the trial, PCa patients with first BCR after previous definitive treatment were prospectively included. Imaging readings were performed both on-site by local specialists and centrally by experts. The economic evaluation extrapolated the diagnostic performances of the imaging techniques using a combination of a decision tree and Markov model based on the natural history of PCa. The health states were non-metastatic and metastatic BCR, non-metastatic and metastatic castration-resistant prostate cancer and death. The state-transition probabilities and utilities associated with each health state were derived from the literature. Real costs were extracted from the National Cost Study of hospital costs and the social health insurance cost schedule.ResultsThere was no significant difference in diagnostic performance among the 3 imaging modalities in detecting bone metastases. FCH was the most cost-effective imaging modality above a threshold incremental cost-effectiveness ratio of 3000€/QALY when imaging was interpreted by local specialists and 9000€/QALY when imaging was interpreted by experts.ConclusionsFCH had a better incremental effect on QALY, independent of imaging reading and should be preferred for detecting bone metastases in patients with biochemical recurrence of prostate cancer.Trial registrationNCT01501630. Registered 29 December 2011.
Project description:The aim of the study was to assess the quality and reproducibility of reducing the injected [18F] sodium fluoride ([18F]NaF) dose while maintaining diagnostic imaging quality in bone imaging in a preclinical skeletal model using digital photon counting PET (dPET) detector technology. Beagles (n = 9) were administered three different [18F]NaF doses: 111 MBq (n = 5), 20 MBq (n = 5), and 1.9 MBq (n = 9). Imaging started ≃45 min post-injection for ≃30 min total acquisition time. Images were reconstructed using Time-of-Flight, ultra-high definition (voxel size of 1 × 1 × 1 mm3), with 3 iterations and 3 subsets. Point spread function was modeled and Gaussian filtering was applied. Skeleton qualitative and quantitative molecular image assessment was performed. The overall diagnostic quality of all images scored excellent (61%) and acceptable (39%) by all the reviewers. [18F]NaF SUVmean showed no statistically significant differences among the three doses in any of the region of interest assessed. This study demonstrated that a 60-fold [18F]NaF dose reduction was not significantly different from the highest dose, and it had not significant effect on overall image quality and quantitative accuracy. In the future, ultra-low dose [18F]NaF dPET/CT imaging may significantly decrease PET radiation exposure to preclinical subjects and personnel.
Project description:BackgroundMetastatic melanoma patients can have durable responses to systemic therapy and even long-term survival. However, a large subgroup of patients does not benefit. Tumour metabolic alterations may well be involved in the efficacy of both targeted and immunotherapy. Knowledge on in vivo tumour glucose uptake and its heterogeneity in metastatic melanoma may aid in upfront patient selection for novel (concomitant) metabolically targeted therapies. The aim of this retrospective study was to provide insight into quantitative 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) parameters and corresponding intra- and inter-patient heterogeneity in tumour 18F-FDG uptake among metastatic melanoma patients. Consecutive, newly diagnosed stage IV melanoma patients with a baseline 18F-FDG PET/CT scan performed between May 2014 and December 2015 and scheduled to start first-line systemic treatment were included. Volume of interests (VOIs) of all visible tumour lesions were delineated using a gradient-based contour method, and standardized uptake values (SUVs), metabolically active tumour volume (MATV) and total lesion glycolysis (TLG) were determined on a per-lesion and per-patient basis. Differences in quantitative PET parameters were explored between patient categories stratified by BRAFV600 and RAS mutational status, baseline serum lactate dehydrogenase (LDH) levels and tumour programmed death-ligand 1 (PD-L1) expression.ResultsIn 64 patients, 1143 lesions ??1 ml were delineated. Median number of lesions ??1 ml was 6 (range 0-168), median maximum SUVpeak 9.5 (range 0-58), median total MATV 29 ml (range 0-2212) and median total TLG 209 (range 0-16,740). Per-patient analysis revealed considerable intra- and inter-patient heterogeneity. Maximum SUVs, MATV, number of lesions and TLG per patient did not differ when stratifying between BRAFV600 or RAS mutational status or PD-L1 expression status, but were higher in the patient group with elevated LDH levels (>?250 U/l) compared to the group with normal LDH levels (P?< 0.001). A subset of patients with normal LDH levels also showed above median tumour 18F-FDG uptake.ConclusionsBaseline tumour 18F-FDG uptake in stage IV melanoma is heterogeneous, independent of mutational status and cannot be fully explained by LDH levels. Further investigation of the prognostic and predictive value of quantitative 18F-FDG PET parameters is of interest.
Project description:Background18F-fluciclovine is a synthetic amino acid positron emission tomography (PET) radiotracer that is approved for use in prostate cancer. In this clinical study, we characterised the kinetic model best describing the uptake of 18F-fluciclovine in breast cancer and assessed differences in tracer kinetics and static parameters for different breast cancer receptor subtypes and tumour grades.MethodsThirty-nine patients with pathologically proven breast cancer underwent 20-min dynamic PET/computed tomography imaging following the administration of 18F-fluciclovine. Uptake into primary breast tumours was evaluated using one- and two-tissue reversible compartmental kinetic models and static parameters.ResultsA reversible one-tissue compartment model was shown to best describe tracer uptake in breast cancer. No significant differences were seen in kinetic or static parameters for different tumour receptor subtypes or grades. Kinetic and static parameters showed a good correlation.Conclusions18F-fluciclovine has potential in the imaging of primary breast cancer, but kinetic analysis may not have additional value over static measures of tracer uptake.Clinical trial registrationNCT03036943.