Figure 4 - uploaded by Mahmoud A Alfeeli
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(A) Stress and rest myocardial perfusion SPECT short, vertical, and horizontal long axis slices and polar maps demonstrate large area of fixed perfusion defect in the inferior, inferolateral, and inferoseptal segments from apex to base. (B) Selected FDG PET/CT transaxial slices show diffusely decreased activity in the left ventricle. FDG uptake is seen in both atria and right ventricle. SPECT = single photon emission computed tomography; FDG = fluorodeoxyglucose; PET/CT = positron emission tomography/computed tomography.
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Objective:
F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) has been increasingly used in myocardial viability imaging. In routine PET viability studies, oral glucose and intravenous insulin loading is commonly utilized. In an optimal study, glucose and insulin loading is expected to cause FDG uptake both in hibernating and normal...
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Citations
... In our recently published study, we found that reduced 18 F-FDG uptake in normal myocardium was more common in PET viable than PET nonviable studies. [15] In PET viable studies, 18 F-FDG uptake in the perfusion defect area and reduced 18 F-FDG uptake in normally perfused myocardium (flip-flop pattern) could be due to higher glucose avidity/need of hibernating myocardium than normal myocardium, preferential use of fatty acids in normal myocardium, or various other factors [ Figure 4]. [15,16] In cases with diffusely reduced 18 F-FDG uptake in normal myocardium, the absence of 18 F-FDG uptake in fixed perfusion defect area may not always indicate nonviability as it could be due to various other factors affecting 18 F-FDG uptake both in normal and hibernating myocardium, such as suboptimal study, inadequacy of the current glucose and insulin loading protocols, or various other patient-related causes such as insulin resistance. ...
... [15] In PET viable studies, 18 F-FDG uptake in the perfusion defect area and reduced 18 F-FDG uptake in normally perfused myocardium (flip-flop pattern) could be due to higher glucose avidity/need of hibernating myocardium than normal myocardium, preferential use of fatty acids in normal myocardium, or various other factors [ Figure 4]. [15,16] In cases with diffusely reduced 18 F-FDG uptake in normal myocardium, the absence of 18 F-FDG uptake in fixed perfusion defect area may not always indicate nonviability as it could be due to various other factors affecting 18 F-FDG uptake both in normal and hibernating myocardium, such as suboptimal study, inadequacy of the current glucose and insulin loading protocols, or various other patient-related causes such as insulin resistance. [17,18] In our current study, we did not find statistical significance in FBG level, amounts of glucose and insulin given, blood glucose after glucose loading and blood glucose at the time of 18 F-FDG injection in PET viable and PET nonviable cases as well in cases with normal and reduced 18 F-FDG uptake in normal myocardium. ...
Oral glucose and intravenous insulin (G/I) loading protocols are commonly used in18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) cardiac viability studies. Although the amount of insulin to be given per blood glucose range has been well described in guidelines, the amount of glucose to be given is not detailed well. In this retrospective study, we aimed to assess if certain parameters, particularly the amount of glucose and insulin given, may affect18F-FDG uptake in the hibernating myocardium and also determine the problems with this protocol.18F-FDG PET cardiac viability study with G/I loading protocols was performed in 49 patients. Fasting blood glucose (FBG), amount of glucose given, blood glucose level after glucose load, amount of insulin given, and blood glucose level at the time of18F-FDG injection were recorded. Statistical analysis was performed to determine if there is any difference in the above values in PET viable and PET nonviable groups and also in subgroups assessing18F-FDG uptake also in normal myocardium. For G/I loading, we used our local protocol in 43 patients, and other protocols in six.18F-FDG PET showed viability in 31 patients, and it was negative for viability in 18. In 22 patients, mainly in PET viable group, there was varying degree of reduced18F-FDG uptake in normal myocardium. There was no significant difference in FBG, amount of glucose given, blood glucose level after glucose load, amount of insulin given, and blood glucose level at the time of18F-FDG injection in PET viable and PET nonviable groups and also in subgroups. The problems with G/I loading protocol included deciding on the amounts of glucose and insulin given, maximum amount of insulin to be given, handling diabetics, optimal time to measure blood glucose after insulin administration, and interpretation of findings in cases with diffusely reduced18F-FDG uptake. Further improvements in current guidelines are necessary to obtain images in optimal conditions for accurate results.
Preclinical and clinical studies have shown that stem cells can promote the regeneration of damaged tissues, but therapeutic protocols need better quality control to confirm the location and number of transplanted cells. This study describes in vivo imaging while assessing reporter gene expression by its binding to a radiolabelled molecule to the respective receptor expressed in target cells. Five mice underwent human skeletal muscle-derived stem/progenitor cell (huSkMDS/PC EF1-HSV-TK) intracardial transplantation after induction of myocardial infarction (MI). The metabolic parameters of control and post-infarction stem progenitor cell-implanted mice were monitored using 2-deoxy-18F-fluorodeoxyglucose ([¹⁸F]-FDG) before and after double promotor/reporter probe imaging with 9-(4-18F-fluoro-3-[hydroxymethyl]butyl)guanine ([¹⁸F]-FHBG) using positron emission tomography (PET) combined with computed tomography (CT). Standardized uptake values (SUVs) were then calculated based on set regions of interest (ROIs). Experimental animals were euthanized after magnetic resonance imaging (MRI). Molecular [¹⁸F]-FHBG imaging of myogenic stem/progenitor cells in control and post-infarction mice confirmed the survival and proliferation of transplanted cells, as shown by an increased or stable signal from the PET apparatus throughout the 5 weeks of monitoring. huSkMDS/PC EF1-HSV-TK transplantation improved cardiac metabolic ([¹⁸F]-FDG with PET) and haemodynamic (MRI) parameters. In vivo PET/CT and MRI revealed that the precise use of a promotor/reporter probe incorporated into stem/progenitor cells may improve non-invasive monitoring of targeted cellular therapy in the cardiovascular system.
Preclinical and clinical studies have shown that stem cells can promote the regeneration of damaged tissues,
but therapeutic protocols need better quality control to confirm the location and number of transplanted cells.
This study describes in vivo imaging while assessing reporter gene expression by its binding to a radiolabelled molecule to the respective receptor expressed in target cells. Five mice underwent human skeletal-derived stem/progenitor cell (huSkMDS/PC EF1-HSV-TK) intracardial transplantation after induction of myocardial infarction (MI). The metabolic parameters of control and post-infarction stem progenitor cell-implanted mice were monitored using 2-deoxy-18F-fluorodeoxyglucose ([¹⁸F]-FDG) before and after double promotor/reporter probe imaging with 9-(4-18F-fluoro-3-[hydroxymethyl]butyl)guanine ([¹⁸F]-FHBG) using positron emission tomography (PET) combined with computed tomography (CT). Standardized uptake values (SUVs) were then calculated based on set regions of interest (ROIs). Experimental animals were euthanized after magnetic resonance imaging (MRI). Molecular [¹⁸F]-FHBG imaging of myogenic stem/progenitor cells in control and post-infarction mice confirmed the survival and proliferation of transplanted cells, as shown by an increased or stable signal from the PET apparatus throughout the 5 weeks of monitoring. huSkMDS/PC EF1-HSV-TK transplantation improved cardiac metabolic ([¹⁸F]-FDG with PET) and haemodynamic (MRI) parameters. In vivo PET/CT and MRI revealed that the precise use of a promotor/reporter probe incorporated into stem/progenitor cells may improve non-invasive monitoring of targeted cellular therapy in the cardiovascular system.
Purpose:
18F-FDG PET myocardial metabolic imaging is used to estimate myocardial viability. However, poor image quality can affect the accurate quantification of viable myocardium. We assessed the feasibility of a rescue protocol that reinjected low-dose 18F-FDG with simultaneous 1 to 2 U of insulin injection and oral administration of 10 g of glucose to improve the image quality of 18F-FDG PET myocardial metabolic imaging.
Patients and methods:
Fifty-one consecutive patients with poor quality to uninterpretable 18F-FDG PET/CT myocardial metabolic images received the rescue protocol immediately after the initial image acquisition. The postrescue image acquisition was performed 1 hour later. The rescue image quality was compared with the initial image. The qualitative visual estimation of the images was graded as follows: grade 0, homogeneous, minimal uptake; grade 1, predominantly minimal or mild uptake; grade 2, moderate uptake; and grade 3, good uptake. The myocardium-to-blood pool activity ratio (M/B) was measured to assess the image quality quantitatively.
Results:
The grades of 0 to 3 were observed in 24 (47%), 27 (53%), 0 (0%), and 0 (0%) patients, respectively, for the initial imaging, and in 0 (0%), 3 (5.9%), 4 (7.8%), and 44 (86.3%) patients for the rescue imaging (P < 0.001). The rescue M/B was significantly higher than the initial M/B (3.4 ± 1.4 vs 1.6 ± 0.6, respectively; P < 0.001).
Conclusions:
The rescue protocol successfully and rapidly improved the quality of myocardial 18F-FDG metabolic imaging.
Cardiovascular disorders are one of the leading causes of death worldwide and are the biggest challenge for modern medicine. Despite a lot of advances, the prevention and management of cardiovascular disorders are the biggest challenge. With the advent of various Molecular Imaging modalities, PET-CT has been well established as an important modality for the evaluation of various conditions. PET-CT can evaluate both anatomical and metabolic changes in a variety of infective inflammatory and myocardial disorders. Myocardial perfusion imaging effectively evaluates the coronary vascularity and other diffuse cardiac involvement. There are a lot of advancements in the diagnosis, treatment, prevention, and events related to cardiovascular disease.
Cardiac PET/MR imaging is an integrated imaging approach that requires less radiation than PET/computed tomography and combines the high spatial resolution and morphologic data from MR imaging with the physiologic information from PET. This hybrid approach has the potential to improve the diagnostic and prognostic evaluation of several cardiovascular conditions, such as ischemic heart disease, infiltrative diseases such as sarcoidosis, acute and chronic myocarditis, and cardiac masses. Herein, the authors discuss the strengths of PET and MR imaging in several cardiovascular conditions; the challenges and potential; and the current data on the application of this powerful hybrid imaging modality.
Purpose
Focal F-18-fluoro-deoxy-glucose uptake in the myocardium can be a sign of resting myocardial ischemia. The purpose of our study was to assess the relevance of performing myocardial perfusion scintigraphy to screen for myocardial ischemia in patients with an incidental finding of focal myocardial F-18-fluoro-deoxy-glucose uptake on a routine F-18-fluoro-deoxy-glucose positron-emission-tomography-computed-tomography.
Methods
In our retrospective multicentric study, patients were included if they had had an incidental finding of myocardial focal F-18-fluoro-deoxy-glucose uptake on a routine F-18-fluoro-deoxy-glucose positron-emission-tomography-computed-tomography and had also undergone myocardial perfusion scintigraphy within 3 months before or after the F-18-fluoro-deoxy-glucose positron-emission-tomography-computed-tomography. Patients with a pattern of ischemia or scar on the myocardial perfusion scintigraphy in the same territory as the focal F-18-fluoro-deoxy-glucose uptake were considered positive.
Results
Seven of the 34 included patients were positive, with an abnormality on the MPS data in the same territory as the focal myocardial F-18-fluoro-deoxy-glucose uptake. 2 of the 6 patients with focal F-18-fluoro-deoxy-glucose uptake in the left anterior descending vascular supply territory and 2 of the 4 patients with focal F-18-fluoro-deoxy-glucose uptake in the standard right coronary artery territory had an abnormal myocardial perfusion scintigraphy. All 12 patients with focal F-18-fluoro-deoxy-glucose uptake restricted to the basal anterolateral and basal inferolateral segments were negative.
Conclusion
Patients with an incidental finding of focal F-18-fluoro-deoxy-glucose uptake on a routine F-18-fluoro-deoxy-glucose positron-emission-tomography-computed-tomography may be considered as being at risk for coronary artery disease, when this uptake is multisegmentary in the same typical coronary territory and not restricted to the basal anterolateral and basal inferolateral segments.
