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- Lindström, Elin, et al.
(författare)
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Regularized reconstruction of digital time-of-flight Ga-68-PSMA-11 PET/CT for the detection of recurrent disease in prostate cancer patients
- 2019
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Ingår i: Theranostics. - : Ivyspring International Publisher. - 1838-7640. ; 9:12, s. 3476-3484
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Tidskriftsartikel (refereegranskat)abstract
- Accurate localization of recurrent prostate cancer (PCa) is critical, especially if curative therapy is intended. With the aim to optimize target-to-background uptake ratio in Ga-68-PSMA-11 PET, we investigated the image quality and quantitative measures of regularized reconstruction by block-sequential regularized expectation maximization (BSREM).Methods: The study encompassed retrospective reconstruction and analysis of 20 digital time-of-flight (TOF) PET/CT examinations acquired 60 min post injection of 2 MBq/kg of Ga-68-PSMA-11 in PCa patients with biochemical relapse after primary treatment. Reconstruction by ordered-subsets expectation maximization (OSEM; 3 iterations, 16 subsets, 5 mm gaussian postprocessing filter) and BSREM (beta-values of 100-1600) were used, both including TOF and point spread function (PSF) recovery. Background variability (BV) was measured by placing a spherical volume of interest in the right liver lobe and defined as the standard deviation divided by the mean standardized uptake value (SUV). The image quality was evaluated in terms of signal-to-noise ratio (SNR) and signal-to-background ratio (SBR), using SUVmax of the lesions. A visual assessment was performed by four observers.Results:OSEM reconstruction produced images with a BV of 15%, whereas BSREM with a beta-value above 300 resulted in lower BVs than OSEM (36% with beta 100, 8% with beta 1300). Decreasing the acquisition duration from 2 to 1 and 0.5 min per bed position increased BV for both reconstruction methods, although BSREM with beta-values equal to or higher than 800 and 1200, respectively, kept the BV below 15%. In comparison of BSREM with OSEM, the mean SNR improved by 25 to 66% with an increasing beta-value in the range of 200-1300, whereas the mean SBR decreased with an increasing beta-value, ranging from 0 to 125% with a beta-value of 100 and 900, respectively. Decreased acquisition duration resulted in beta-values of 800 to 1000 and 1200 to 1400 for 1 and 0.5 min per bed position, respectively, producing improved image quality measures compared with OSEM at a full acquisition duration of 2 min per bed position. The observer study showed a slight overall preference for BSREM beta 900 although the interobserver variability was high.Conclusion:BSREM image reconstruction with beta-values in the range of 400-900 resulted in lower BV and similar or improved SNR and SBR in comparison with OSEM.
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| 3. |
- Regula, Naresh Kumar, et al.
(författare)
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Comparison of Ga-68-PSMA PET/CT with fluoride PET/CT for detection of bone metastatic disease in prostate cancer
- 2022
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Ingår i: European Journal of Hybrid Imaging. - : Springer Nature. - 2510-3636. ; 6:1
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Tidskriftsartikel (refereegranskat)abstract
- Background F-18-NaF positron emission tomography/computed tomography (fluoride PET/CT) is considered the most sensitive technique to detect bone metastasis in prostate cancer (PCa). Ga-68-PSMA-11 (PSMA) PET/CT is increasingly used for staging of PCa. This study primarily aimed to compare the diagnostic performance of fluoride PET/CT and gallium-based PSMA PET/CT in identifying bone metastasis followed by a comparison of PSMA PET/CT with contrast-enhanced CT (CE-CT) in identifying soft tissue lesions as a secondary objective. Methods Twenty-eight PCa patients with high suspicion of disseminated disease following curative treatment were prospectively evaluated. PET/CT examinations using fluoride and PSMA were performed. All suspicious bone lesions were counted, and the tracer uptake was measured as standardized uptake values (SUV) for both tracers. In patients with multiple findings, ten bone lesions with highest SUVmax were selected from which identical lesions from both scans were considered for direct comparison of SUVmax. Soft tissue findings of local and lymph node lesions from CE-CT were compared with PSMA PET/CT. Results Both scans were negative for bone lesions in 7 patients (25%). Of 699 lesions consistent with skeletal metastasis in 21 patients on fluoride PET/CT, PSMA PET/CT identified 579 lesions (83%). In 69 identical bone lesions fluoride PET/CT showed significantly higher uptake (mean SUVmax: 73.1 +/- 36.8) compared to PSMA PET/CT (34.5 +/- 31.4; p < 0.001). Compared to CE-CT, PSMA PET/CT showed better diagnostic performance in locating local (96% vs 61%, p = 0.004) and lymph node (94% vs 46%, p < 0.001) metastasis. Conclusion In this prospective comparative study, PSMA PET/CT detected the majority of bone lesions that were positive on fluoride PET/CT. Further, this study indicates better diagnostic performance of PSMA PET/CT to locate soft tissue lesions compared to CE-CT.
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| 4. |
- Regula, Naresh Kumar, et al.
(författare)
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Dynamic Imaging of Prostate Cancer with 11C-acetate PET/CT
- 2017
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Ingår i: Journal of Nuclear Medicine. - 0161-5505 .- 1535-5667. ; 58:S1
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Objectives: Dynamic 11C-acetate PET/CT can be used to study tissue perfusion and carbon flux simultaneously, but studies in cancer are limited. We investigated the kinetics of 11C-acetate in prostate cancer subjects using parametric images with an image-derived input function (IDIF).Methods: Twenty-one patients with newly diagnosed low-moderate risk prostate cancer were studied. All underwent pelvic MRI. Dynamic 11C-acetate (5 MBq/kg) PET/CT of the pelvis was acquired for 32 minutes with 32 time frames. An IDIF was acquired from iliac vessels with multiple small regions of interest (ROIs) and a standardized metabolite correction. Parametric images of K1 (extraction), k2 (oxidative metabolism) and Vd (=K1/k2, anabolic metabolism defined as carbon retention) were constructed using a one-tissue compartment model. ROIs of the largest cancer region in each patient and normal prostate tissue were drawn using information from MRI (T2 and DWI images) and from post-surgical histopathology of whole prostate sections (n=7).Results: Mean PSA was 8.3±3.9. Median Gleason Sum was 6 (range 5-7). K1, Vd and SUVs were higher in cancerous regions compared to normal prostate for all patients (p<0.001). PSA correlated to early SUV (r=0.50, p=0.02) and K1 (r=0.48, p=0.03). Early and late SUVs were correlated to Vd (r>0.76, p<0.001) and K1 (r>0.61, p<0.005).Conclusion: Parametric images could be used to visualize the 11C-acetate kinetics of the prostate. In this cohort of relatively low-risk cancers, PSA values were related to cancer perfusion. SUV of cancerous regions at any time point is primarily associated with anabolic metabolism. Research Support: Swedish Cancer Foundation (Cancerfonden)
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| 5. |
- Regula, Naresh Kumar, 1985-
(författare)
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PET in Prostate Cancer – Detection, Tumour Biology and Prognosis
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Prostate cancer (PCa) is the most common non-cutaneous malignancy in men and the leading cause of cancer-related deaths in Sweden. Despite the major advances, the current diagnostic modalities fall short of standards, specifically, precise localization required for effective management of the PCa. positron emission tomography (PET) combined with computed tomography (CT) has evolved as a promising diagnostic imaging technique for PCa. The progression of the PCa is often associated with metabolic alterations and overexpression of several proteins. Increased de novo fatty acid synthesis and prostate-specific membrane antigen (PSMA) overexpression are some of the distinctive features linked with PCa growth and the potential targets for the development of PET radiotracers. This thesis is based on four original articles and focuses on the utilization of some of several different PET tracers available to visualize PCa spread. The work can be divided into two distinctive parts: (1) evaluate the prognostic value of 11C-acetate PET/CT towards survival in the setting of biochemical relapse after surgery, investigate tumour biology using single-tissue compartment model derived parametric images of 11C-acetate dynamic PET/CT both at patient and cell level and (2) the comparison of 68Ga-PSMA-11 PET/CT with 11C-acetate PET/CT and 18F-NaF PET/CT in patients with PCa relapse depicting different aspects of PCa biology.We demonstrated that quantification of 11C-acetate accumulation in PCa lesions was a strong predictor of survival in patients with biochemical relapse. Furthermore, parametric images of 11C-acetate dynamic PET/CT enabled visualization of tumour biology exhibiting elevated extraction of 11C-acetate associated with cancer aggressiveness also confirmed in in-vitro studies. 68Ga-PSMA-11 PET/CT located more widespread disease and performed significantly better in locating lymph node and bone metastases compared to 11C-acetate PET/CT. Similarly, 68Ga-PSMA-11 PET/CT was able to detect most of the bone lesions detected with 18F-NaF PET/CT along with additional soft tissue lesions.In conclusion, we showed the role of 11C-acetate PET/CT in PCa prognosis with additional understanding of tumour biology. Further, we successfully showed better performance of 68Ga-PSMA-11 PET/CT in locating PCa relapse and established it as a promising option for PCa re-staging.
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