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- Kero, Tanja
(författare)
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Methodological aspects of quantitative cardiac molecular imaging
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The objective of this research was to facilitate the use of quantitative cardiac molecular imaging by developing and validating methods and applications. More specifically:we determined the optimal tracer kinetic model for analysis of 11C-PIB and evaluated the performance of two simpler measures, retention index (RI) and standardized uptake value (SUV), in the quantification of cardiac 11C-PIB uptake in amyloidosis. An irreversible two-tissue (2Tirr) model best described the 11C-PIB uptake in cardiac amyloidosis. RI and SUV showed high correlation with quantitative results from this kinetic model and also a better discrimination between amyloidosis patients and controls than a 2Tirr model with population averaged metabolite correction. RI and SUV are furthermore more feasible for use in clinical routine and therefore the preferred measure to use in PET diagnosis of cardiac amyloidosis. We also tested the feasibility of a semiautomatic software to analyze RI and visualize cardiac uptake of 11C-PIB in amyloidosis. The RI values were comparable with RI based on manual segmentation, showing significantly higher 11C-PIB RI in amyloidosis patients than in healthy volunteers. A fast and accurate semiautomatic analysis process is thus feasible to use for PET in cardiac amyloidosis instead of the laborious manual analyses that were used so far.Furthermore, we assessed the quantitative accuracy of cardiac perfusion measurements with 15O-water PET in a digital time-of-flight PET-MR scanner. A high correlation and agreement between PET-MR based and PET-CT based MBF was found; cardiac perfusion measurements with 15O-water can therefore be performed accurately with the fully integrated Signa PET-MR scanner. Finally, we assessed the quantitative accuracy of cardiac perfusion measurements using dynamic contrast-enhanced MRI with simultaneous 15O-water PET as reference at rest and during adenosine-induced hyperemia with a fully integrated PET-MR scanner. The correlations between global and regional MRI- and PET-based MBF values were good and the biases were negliable for both global and regional MBF comparisons, but the limits of agreement were wide for both global and regional MBF, with larger variability for high MBF-values indicating that MRI-based quantitative MBF measurement based on widely available acquisition protocols is not yet ready for clinical introduction.
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| 2. |
- Lindgren Belal, Sarah, et al.
(författare)
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Automated quantification of PET/CT skeletal tumor burden in prostate cancer using artificial intelligence: The PET index
- 2023
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Ingår i: European Journal of Nuclear Medicine and Molecular Imaging. - : Springer Science and Business Media LLC. - 1619-7070 .- 1619-7089. ; 50:5, s. 1510-1520
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Tidskriftsartikel (refereegranskat)abstract
- Purpose Consistent assessment of bone metastases is crucial for patient management and clinical trials in prostate cancer (PCa). We aimed to develop a fully automated convolutional neural network (CNN)-based model for calculating PET/CT skeletal tumor burden in patients with PCa. Methods A total of 168 patients from three centers were divided into training, validation, and test groups. Manual annotations of skeletal lesions in -[F-18]fluoride PET/CT scans were used to train a CNN. The AI model was evaluated in 26 patients and compared to segmentations by physicians and to a SUV 15 threshold. PET index representing the percentage of skeletal volume taken up by lesions was estimated. Results There was no case in which all readers agreed on prevalence of lesions that the AI model failed to detect. PET index by the AI model correlated moderately strong to physician PET index (mean r = 0.69). Threshold PET index correlated fairly with physician PET index (mean r = 0.49). The sensitivity for lesion detection was 65-76% for AI, 68-91% for physicians, and 44-51% for threshold depending on which physician was considered reference. Conclusion It was possible to develop an AI-based model for automated assessment of PET/CT skeletal tumor burden. The model's performance was superior to using a threshold and provides fully automated calculation of whole-body skeletal tumor burden. It could be further developed to apply to different radiotracers. Objective scan evaluation is a first step toward developing a PET/CT imaging biomarker for PCa skeletal metastases.
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| 3. |
- Vyakaranam, Achyut Ram
(författare)
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Nuclear medicine imaging and treatment in pheochromocytoma, paraganglioma, and role of the new tracer 11C-hydroxy ephedrine in diabetes mellitus
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Carbon-11 hydroxy ephedrine (11C-HED) is a norepinephrine analog which binds to the norepinephrine receptor present in adrenal medulla, lung, liver and pancreas. 11C-HED-positron emission tomography with concomitant computed tomography (PET/CT) can image these organs. Pheochromocytoma (PCC) and Paraganglioma (PGL) are rare, chromaffin cell tumors, which may mimic other diseases and can be difficult to diagnose because of vague and uncharacteristic symptoms. The diagnosis of PCC/PGL is reached either by detection of excessive catecholamines or metanephrines in plasma or urine, or may be detected incidentally on computed tomography (CT)/magnetic resonance imaging (MRI) as an “incidentaloma”. Also, these tumors are most heritable endocrine neoplasms, and can metastasize in up to 20% of patients. Better post-operative surveillance, re-staging on evidence of recurrent disease, biochemical recurrence and therapy monitoring is needed in these patients to improve care. Also, in inoperable cases and metastatic disease of neuroendocrine tumors (NETs), peptide receptor radiotherapy (PRRT) with 177Lu-DOTATATE has emerged as a promising nuclear medicine therapy. Recent studies have shown a connection between sympathetic nervous system and diabetes mellitus both type 1(T1D) and type 2(T2D), which are a global health burden. However, underlying pathophysiology of both types are not well understood. The aims of this thesis was, in Paper I to establish the role of 11C-HED PET/CT in complex clinical scenarios to diagnose or rule out primary tumors of PCC/PGL (n=102). In Paper II, to determine the outcome of treatment with 177Lu-DOTATATE in PCC/PGL (n=22), in Paper III to assess the additional clinical benefit of 11C-HED PET/CT in in patients with metastatic PCC/PGL in comparison to morphological imaging, CT/MRI and other available imaging (n=74), in Paper IV to establish 11C-HED PET/CT for non-invasive imaging of the pancreatic sympathetic innervation in individuals with T2D (n=25) and non-diabetics (n=64).We demonstrate that 11C-HED PET/CT is a valuable diagnostic tool to diagnose or rule out pheochromocytoma and paraganglioma. Also, it is excellent in surveilling metastatic disease post-surgery, monitoring therapy with parameters such as standardized uptake value (SUV) and total catecholamine transporter tumor volume (TCTTV) and provides additional benefit in complex clinical scenarios. Upon treatment with 177Lu-DOTATATE patients with PCC/PGL had a favorable outcome with low toxicity. There was focal accumulation of 11C-HED in the sympathetic innervation of the pancreas and CT helped in delineation and further segmentation. In conclusion, we showed the role of new radiotracer 11C-HED and theragnostic option, PRRT with 177Lu-DOTATATE successfully better nuclear medicine diagnosis and therapy in pheochromocytoma, paraganglioma and diabetes mellitus.
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