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Quantitative PET/CT for radiomics
Published in Ruijiang Li, Lei Xing, Sandy Napel, Daniel L. Rubin, Radiomics and Radiogenomics, 2019
Stephen R. Bowen, Paul E. Kinahan, George A. Sandison, Matthew J. Nyflot
While many PET radiomics investigations have focused on cancer phenotyping, applications extend beyond oncology. Pulmonary ventilation and perfusion imaging with [68Ga]Galligas and [68Ga]macro-aggregated albumin (MAA), respectively, could be utilized for PET radiomic feature extraction and correlation with pulmonary toxicity risk following surgery or radiation therapy in lung cancer patients. These high-risk patients could then be selected for normal tissue sparing therapeutic strategies. Cardiac PET radiomics may improve diagnosis of defects or risk of cardiac toxicity and perhaps reduce the need for complex cardiac-gated dynamic acquisitions through feature extraction on simple static images. FDG PET or FLT PET radiomics of bone marrow may better identify patients who are at risk for hematopoietic toxicity and require marrow-sparing therapeutic strategies. Radiomics of beta amyloid PET, tau PET, and other brain PET imaging may identify early predictive signatures of Alzheimer’s and other neurodegenerative diseases. While not an exhaustive list, these conceptual examples demonstrate the enormous clinical potential of normal tissue function radiomics combined with data analytics.
Cardiovascular PET-CT
Published in Yi-Hwa Liu, Albert J. Sinusas, Hybrid Imaging in Cardiovascular Medicine, 2017
Etienne Croteau, Ran Klein, Jennifer M. Renaud, Manuja Premaratne, Robert A. Dekemp
Positron emission tomography (PET) is the leading tool in nuclear cardiology for noninvasive assessment of molecular function. Images are obtained via detection of positrons emitted from the decay of an injected radiotracer. Radiotracers are either short-lived isotopes themselves, such as 82Rb, or isotopes that have been incorporated into biological or drug compounds, such as 18F-fluoro-deoxyglucose or 11C-methyl-losartan, respectively. The amount of tracer injected is low enough such that it does not affect the physiological process being imaged. Most isotopes are produced in a cyclotron and undergo radiochemical synthesis to be incorporated into a tracer molecule, requiring an onsite or local cyclotron due to the short half-lives. There has been a shift toward simpler and more cost-effective onsite alternatives, such as the generator-produced tracer 82Rb. Some of the most common clinical and research-based cardiac PET tracers, their characteristics, applications, and the associated imaging protocols are listed in Table 2.1 (Zober et al. 2006; Thackeray and Bengel 2013; Danad, Raijimakers, and Knaapen 2013).
Non-invasive cardiac imaging for the interventionist
Published in Ever D. Grech, Practical Interventional Cardiology, 2017
Pankaj Garg, David P Ripley, John P Greenwood, Sven Plein
Cardiac PET is a nuclear medicine technique using intravenous injection of a radiotracer for the evaluation of perfusion and viability. PET can be used to quantify both perfusion and metabolism as well as determine myocardial viability. PET requires the use of cyclotron-produced positron-emitting isotopes (e.g. 82rubidium, 13N-ammonia). Although there is less evidence than for MPS, meta-analyses have suggested that PET has higher sensitivity for the detection of CAD than MPS, including in women and obese patients,31,32 likely due to its higher spatial resolution. The ESC guidelines for the management of stable chest pain include PET as an non-invasive stress imaging option.4 PET is the gold standard test for the non-invasive quantification of myocardial blood flow, allowing the detection of microvascular disease.
Non-invasive imaging techniques to assess myocardial perfusion
Published in Expert Review of Medical Devices, 2020
Olivier Villemain, Jérôme Baranger, Zakaria Jalal, Christopher Lam, Jérémie Calais, Mathieu Pernot, Barbara Cifra, Mark K. Friedberg, Luc Mertens
Ultimately, it seems intuitive to say that the next generation of imaging for myocardial perfusion analysis will be hybrid (or fusion) techniques combining several techniques and combining their strengths. The CT-SPECT combination (Figure 5) is one possible example, as is the Ultrasound-PET combination. Since 2010, hybrid PET/MRI using sequential and integrated scanner platforms has been available, with hybrid cardiac PET/MR imaging protocols increasingly incorporated into clinical workflows. Given the range of complementary information provided by each method, the use of hybrid PET/MRI may be justified and beneficial in particular clinical settings for the evaluation of different disease entities. Indeed, as summarized in this Review paper, each technique has its inherent limitations in the underlying physics. But being able to combine the advantages of each would allow research and medical teams to go further in the analysis of myocardial perfusion. Through the development of other technologies, such as machine learning, automatic image analysis, or potential robotization (for the automatic performance of echocardiography), the association and combination of imaging techniques will become more accessible and reliable.
Cardiac sarcoidosis – an expert review for the chest physician
Published in Expert Review of Respiratory Medicine, 2019
Jamie S. Y. Ho, Edwin R. Chilvers, Muhunthan Thillai
Experts from three independent organisations have developed consensus pathways for diagnosis of CS in the absence of direct EMB histological evidence (Table 4). As they do not have prognostic evidence regarding clinical use, it is unclear which of these is more accurate in diagnosing CS. The original 1993 JMHW criteria are reported to miss almost half of those diagnosed with the 2006 update, some of whom will go on to experience malignant VT [83]. All of the guidelines involve clinical presentations of reduced LVEF, conduction disturbances, ventricular arrhythmias, as well as positive gallium scan, LGE-CMR and cardiac PET uptake. These have been combined to propose a simple diagnostic pathway, which can be used to determine the need for advanced cardiac testing in suspected CS (Figure 4).
The role of late gadolinium enhancement in predicting arrhythmic events in cardiac sarcoidosis patients – a mini-review
Published in Acta Cardiologica, 2022
George Bazoukis, Ioannis Liatakis, Vassilios S. Vassiliou, Gary Tse, Pantelis Gounopoulos, Athanasios Saplaouras, Konstantinos P. Letsas, Konstantinos Vlachos, Stamatis S. Papadatos, Eleni Konstantinidou, Ioannis Lakoumentas, Antonios Sideris, Michael Efremidis
The cardiac involvement in the clinical setting of sarcoidosis includes three successive histological stages: oedema, granulomatous inflammation, and fibrosis (scar) [16]. Various patterns of LGE have been described in CS patients, but findings are usually patchy and multifocal with subendocardial sparing. Occasionally CS may demonstrate subendocardial LGE mimicking a prior myocardial infarction. Specifically, typical LGE patterns in CS patients include subepicardial and mid-wall LGE along the basal septum, while an extension into the right ventricular insertion points as well as the inferolateral wall can be noted [17,18]. The presence of LGE is associated with a worse prognosis and arrhythmic risk. Discrimination of oedema from a myocardial scar is crucial for prognostic purposes. A CMR examination when the patient is no longer in the acute phase or a multiparametric mapping with T2 can help to confirm the scar-related LGE by identifying areas of reversible myocardial tissue pathology, including oedema and inflammation [19]. Regarding the pathophysiology of arrhythmogenesis in the setting of CS, scar formation instead of active inflammation seems to serve as the main arrhythmogenic substrate [20,21]. Specifically, one study showed that among the seven CS patients with sustained VT, only one patient had cardiac inflammation by Gallium-67 citrate scintigraphy [21]. Similarly, another study included CS patients with VT history who underwent CMR, PET, and electroanatomical mapping [20]. The authors found that myocardial segments with abnormal electrograms tended to have more scar as depicted by CMR and less inflammation by PET [20]. On the other hand, a retrospective study showed a significant association between focal FDG uptake on cardiac PET (a marker of inflammation) with future VT or death [22]. However, the retrospective nature of this study makes it unclear if inflammation and not a downstream scar formation is the primary pathophysiological mechanism of VT occurrence in CS patients [22].