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Quantification in Emission Tomography
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
Brian F. Hutton, Kjell Erlandsson, Kris Thielemans
A common metric for quantification of tracer uptake is the standardized uptake value (SUV). This has been widely used in PET but is now also gaining popularity applied to SPECT. In its basic form, this metric is obtained as the maximum (or mean) activity concentration in a target region, CT, measured a fixed time after administration, normalized to the injected activity, Ainj, per unit of body weight, W, of the patient:
Neuroimaging in Nuclear Medicine
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
Anne Larsson Strömvall, Susanna Jakobson Mo
A visual interpretation is often done in combination with a quantitative or semi-quantitative technique to support the visual interpretation and improve the diagnostic accuracy, or to get numerical values to assess the specific uptake in a specific region. Basic semi-quantitative approaches rely on ROIs or VOIs that are drawn manually or are automatically applied to the structure of interest and to a reference region. A simple ratio or a specific uptake ratio can then be calculated from the average values in the respective regions. The standardized uptake value (SUV) is often used in PET, in which the uptake value is standardized to, for example, body weight and the amount of injected activity.
Radionuclide Imaging in Treatment Planning
Published in W. P. M. Mayles, A. E. Nahum, J.-C. Rosenwald, Handbook of Radiotherapy Physics, 2021
For PET imaging, a metric commonly used to quantify the local uptake of radiotracer is the standardised uptake value (SUV), defined as the ratio of the radioactive concentration to the net injected activity) divided by a normalisation factor associated with a volume related to the dilution of the radiotracer in the patient's body:
Artificial intelligence-based measurements of PET/CT imaging biomarkers are associated with disease-specific survival of high-risk prostate cancer patients
Published in Scandinavian Journal of Urology, 2021
Eirini Polymeri, Henrik Kjölhede, Olof Enqvist, Johannes Ulén, Mads H. Poulsen, Jane A. Simonsen, Pablo Borrelli, Elin Trägårdh, Åse A. Johnsson, Poul Flemming Høilund–Carlsen, Lars Edenbrandt
However, the analysis and clinical reports for PET/CT still rely predominantly on visual assessment and semi-automated measurements; probably due to the fact that proper quantification of disease processes is time-consuming and mainly based on manual procedures. Visual assessment is associated with inter-observer variability both in clinical reporting and research. Further, the most easily obtained measurement available is the maximum standardised uptake value (SUVmax). The prognostic significance of the sum of SUVmax in patients with prostate cancer was presented several years ago [7], though the clinical value of this measurement has been shown to be relatively limited, especially when it comes to evaluation of tumour response [8,9]. One reason for this could be that SUVmax may be biased by disproportionate uptake in a relatively small amount of tissue, and may not correlate to total disease burden.
Mediastinal lymphadenopathy: a practical approach
Published in Expert Review of Respiratory Medicine, 2021
Hariharan Iyer, Abhishek Anand, PB Sryma, Kartik Gupta, Priyanka Naranje, Nishikant Damle, Saurabh Mittal, Neha Kawatra Madan, Anant Mohan, Vijay Hadda, Pawan Tiwari, Randeep Guleria, Karan Madan
As discussed in the sections above, a false positive PET scan with high SUV values may be seen in certain benign conditions. One technique useful in such scenarios is delayed (dual time point [DTP]) PET/CT scan to characterize such lesions [42]. In this technique, after obtaining an initial scan after administration of 18F-FDG, a second delayed scan is obtained around an hour or two after the initial scans. In malignant cells, there is a gradual accumulation of FDG, leading to a higher SUV in the delayed scan. In contrast, in benign diseases due to infectious or inflammatory pathology such as sarcoidosis and histoplasmosis, there is a fall in the SUV on the delayed scan. This is due to the differential expression of glucose-6-phosphatase and hexokinase in the cells [43,44]. This technique has been reported to have a positive predictive value of 80% and a negative predictive value of 100% for differentiating benign and malignant intrathoracic lesions [42]. This study found that certain benign diseases such as sarcoidosis, Histoplasmosis and hamartomas having an initial high SUV had a fall in the delayed scan values [42].
Radiofrequency ablation for treatment of thyroid follicular neoplasm with low SUV in PET/CT study
Published in International Journal of Hyperthermia, 2021
Wei-Che Lin, Yu-Cheng Tung, Yen-Hsiang Chang, Sheng-Dean Luo, Pi-Ling Chiang, Shun Chen Huang, Wei-Chih Chen, Chen-Kai Chou, Yan-Ye Su, Wen-Chieh Chen, Shun-Yu Chi, Jung Hwan Baek
All patients, who had fasted for at least 4 h, were injected intravenously with a single bolus dose of 370–440 MBq of F-18 FDG. The head and neck F-18 FDG PET/CT images were obtained 1 h later using PET/CT scanner (Discovery ST PET/CT system; GE healthcare, Waukesha WI, USA). Unenhanced CT scans were acquired for attenuation correction and imaging fusion, PET scans (5 min/bed) were then performed from vertex to upper chest. The PET images were attenuation-corrected based on the CT images and reconstructed to a resolution of 5.47 × 5.47 × 3.27 mm using an ordered subsets expectation maximization (OSEM) algorithm. Blood glucose levels were checked in all patients prior to F-18 FDG injection, and no patients showed a blood glucose level of >180 mg/dL. For semiquantitative analysis of FDG uptake, region of interest (ROIs) were defined on the target lesion (thyroid nodule) in the transaxial PET images. The maximum standard uptake value (SUV) was calculated by using the following formula: