Background: Static [ 18 F]-F-DOPA PET images are currently used for identifying patients with glioma recurrence/ progression after treatment, although the additional diagnostic value of dynamic parameters remains unknown in this setting. The aim of this study was to evaluate the performances of static and dynamic [ 18 F]-F-DOPA PET parameters for detecting patients with glioma recurrence/progression as well as assess further relationships with patient outcome. Methods: Fifty-one consecutive patients who underwent an [ 18 F]-F-DOPA PET for a suspected glioma recurrence/ progression at post-resection MRI, were retrospectively included. Static parameters, including mean and maximum tumor-to-normal-brain (TBR) ratios, tumor-to-striatum (TSR) ratios, and metabolic tumor volume (MTV), as well as dynamic parameters with time-to-peak (TTP) values and curve slope, were tested for predicting the following: (1) glioma recurrence/progression at 6 months after the PET exam and (2) survival on longer follow-up. Results: All static parameters were significant predictors of glioma recurrence/progression (accuracy ≥ 94%) with all parameters also associated with mean progression-free survival (PFS) in the overall population (all p < 0.001, 29.7 vs. 0.4 months for TBR max , TSR max , and MTV). The curve slope was the sole dynamic PET predictor of glioma recurrence/ progression (accuracy = 76.5%) and was also associated with mean PFS (p < 0.001, 18.0 vs. 0.4 months). However, no additional information was provided relative to static parameters in multivariate analysis. Conclusion: Although patients with glioma recurrence/progression can be detected by both static and dynamic [ 18 F]-F-DOPA PET parameters, most of this diagnostic information can be achieved by conventional static parameters.
Pituitary macroadenoma constitutes a frequently misdiagnosed benign tumor. We report herein a case where such macroadenoma, a prolactinoma, was incidentally discovered in a 63-year-old man who had been referred to F-FDG PET and F-FDOPA PET imaging for a pharmacoresistant epilepsy. An increased uptake was documented for both radiotracers within the sellar region, although with a much higher contrast for F-FDOPA than for F-FDG. This case presents an increased uptake documented within a prolactinoma owing to the high contrast and image quality provided by F-FDOPA PET.
Background: Static 18 F-FDopa PET images are currently used for identifying patients with glioma recurrence/progression after treatment, although the additional diagnostic value of dynamic parameters remains unknown in this setting. The aim of the present study was to evaluate the performances of static and dynamic 18 F-FDopa PET parameters for detecting patients with glioma recurrence/progression as well as to assess further relationships with patient outcome. Fifty-one consecutive patients who underwent an 18 F-FDopa PET for a suspected glioma recurrence/progression at post-resection MRI, were retrospectively included. Static parameters including mean and maximum tumor-to-normal-brain (TBR), tumor-to-striatum (TSR) ratios, and metabolic tumor volume (MTV), as well as dynamic parameters with time-to-peak (TTP) values and curve slope, were tested for predicting: 1) glioma recurrence/progression at 6-months after the PET exam and 2) survival on longer follow-up. Results: All static parameters were significant predictors of a glioma recurrence/progression (accuracy≥94%) with all parameters also associated with mean progression-free survival (PFS) in the overall population (all p<0.001, 29.7 vs. 0.4 months for TBR max , TSR max and MTV). The curve slope was the sole dynamic PET predictor of glioma recurrence/progression (accuracy=76.5%) and was also associated with the mean PFS (p<0.001, 18.0 vs. 0.4 months). However, no additional information was provided relative to static parameters in multivariate analysis. Conclusion: Although patients with glioma recurrence/progression can be detected by both static and dynamic 18 F-FDopa PET parameters, most of this diagnostic information can be achieved by conventional static parameters.
Background Patient radioprotection in myocardial perfusion imaging (MPI)-SPECT is important but difficult to optimize. The aim of this study was to adjust injected activity according to patient size—weight or BMI—by using a cardiofocal collimator camera. Methods The correlation equation between size and observed counts in image was determined in patients who underwent stress Tc-99m-sestamibi MPI-SPECT/CT with a cardiofocal collimator-equipped conventional Anger SPECT/CT system. Image quality analyses by seven nuclear physicians were conducted to determine the minimum patient size-independent observed count threshold that yielded sufficient image quality for perfusion-defect diagnosis. These data generated an equation that can be used to calculate personalized activity for patients according to their size. Results Analysis of consecutive patients (n = 294) showed that weight correlated with observed counts better than body mass index. The correlation equation was used to generate the equation that expressed the relationship between observed counts, patient weight, and injected activity. Image quality analysis with 50 images yielded an observed count threshold of 22,000 counts. Using this threshold means that the injected activity in patients with < 100 kg would be reduced (e.g., by 67% in 45-kg patients). Patients who are heavier than 100 kg would also benefit from the use of the threshold because although the injected activity would be higher (up to 78% for 150-kg patients), good image quality would be obtained. Conclusions This study provided a method for determining the optimal injected activity according to patient weight without compromising the image quality of conventional Anger SPECT/CT systems equipped with a cardiofocal collimator. Personalized injected activities for each patient weight ranging from 45 to 150 kg were generated, to standardize the resulting image quality independently of patient attenuation. This approach improves patient/staff radioprotection because it reduces the injected activity for < 100-kg patients (the majority of patients).
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