Blood Pool Standardized Uptake Value Research Articles

Usefulness of 18F-FDG PET/computed tomography in differentiating between subacute and chronic aortic dissection: initial investigation.

In the selection of thoracic endovascular repair for aortic dissection (AD), it is important to distinguish between the subacute and chronic phases, but there is no reliable way to distinguish between them in patients with unknown onset of AD. The purpose of this study was to assess the diagnostic performance of 2-[18F] fluoro-2-deoxy-d-glucose (18F-FDG)-PET/computed tomography (PET/CT) for discriminating subacute AD from chronic AD. Thirteen patients with AD who were medically treated and followed up for 6 months were studied. 18F-FDG PET/CT images were obtained for each patient in the subacute phase (the first scan) and at 6 months (the second scan) after the onset. Target-to-background ratio (TBR) was measured as the maximum standardized uptake value (SUV) in the dissected aortic wall divided by blood pool SUV. TBR was significantly higher in the first scan (mean ± SD, 1.97 ± 0.32) than in the second scan (1.69 ± 0.29, P = 0.007). The area under the receiver operating characteristic curve of TBR for discriminating subacute AD from chronic AD was 0.76. With a threshold of 1.74, the TBR showed the sensitivity, specificity, and positive and negative predictive value of 85%, 69%, 73%, and 82%, respectively, for the discrimination of subacute AD from chronic AD. Metabolic assessment of dissected aortic wall by 18F-FDG PET/CT is useful in differentiating between subacute and chronic AD and can provide important information in determining the appropriate indication for treatment for patients with AD of unknown onset.

Pilot Study of F18-Florbetapir in the Early Evaluation of Cardiac Amyloidosis.

Background: Cardiac amyloidosis is an increasingly recognized etiology of heart failure, in part due to the rise of non-invasive nuclear bone scintigraphy. Molecular imaging using positron emission tomography (PET) has promised the direct visualization of cardiac amyloid fibrils. We sought to assess the performance of F18-florbetapir PET in patients with a potential for cardiac amyloidosis in order to identify early disease.Methods: We performed a pilot study of 12 patients: one with asymptomatic transthyretin cardiac amyloidosis, seven with a potential for developing cardiac amyloidosis (two smoldering myeloma and five with extracardiac biopsy demonstrating transthyretin amyloid deposits and negative technetium pyrophosphate scans), and four controls. Patients were imaged with PET/CT in listmode 10–20 min after receiving F18-florbetapir. Static images were created from this acquisition, and mean standardized uptake values (SUVs) of the left ventricular myocardium, blood pool, paraspinal muscles, and liver were calculated.Results: All 12 patients demonstrated radiotracer uptake in the myocardium with mean SUV of 2.3 ± 0.4 and blood pool SUV of 0.8 ± 0.1. The patient with cardiac amyloidosis had SUV of 3.3, while mean SUV for patients at risk was 2.3 ± 0.4 and for controls was 2.2 ± 0.3. After 3 years of follow-up, one patient with SUV below the mean was subsequently diagnosed with ATTR cardiac amyloidosis.Conclusion: In this cohort, PET with F18-florbetapir demonstrated non-specific radiotracer uptake in the myocardium in all patients using a static image protocol; though, the highest values were noted in a patient with ATTR cardiac amyloidosis. There was no difference in the intensity of F18-florbetapir uptake in at-risk patients and controls. Future studies should continue to investigate metabolic PET tracers and protocols in cardiac amyloidosis, including in early disease.

18F-FDG-PET/CT Evaluation of Indeterminate Adrenal Masses in Noncancer Patients.

Adrenal tumors in noncancer patients are common. Evaluate performance of 18F-fluorodeoxyglucose positron emission tomography computed tomography (18F-FDG-PET/CT) in distinguishing between benign and malignant adrenal tumors. Retrospective chart review 2010-2019. Academic institution. One hundred and seventeen noncancer patients, defined as having no history of cancer or with cancer in remission for ≥5 years, completed 18F-FDG-PET/CT to evaluate adrenal masses, with pathologic diagnoses or imaging follow-up (≥12 months). 18F-FDG-PET/CT of 117 indeterminate adrenal masses. Receiver operator characteristic curve of the ratios of adrenal lesion standardized uptake value (SUV)max to liver SUVmean and of adrenal lesion SUVmax to aortic arch blood pool SUVmean were constructed. Seventy benign and 47 malignant masses (35 adrenocortical carcinomas [ACCs], 12 adrenal metastases) were identified. Malignant masses had higher median liver SUV and blood pool SUV ratios than benign masses (6.2 and 7.4 vs 1.4 and 2.0, P < .001). Median liver and blood pool SUV ratios of ACC (6.1 and 7.3, respectively) and metastases (6.7 and 7.7, respectively) were higher than those of than adenomas (1.4 and 2.2, P < .05 for all comparisons). Optimal liver SUV ratio to discern between benign and malignant masses was 2.5, yielding 85% sensitivity, 90% specificity, and 7 false negative results (including 3 ACCs). Optimal blood pool SUV ratio was 3.4, yielding 83% sensitivity, 90% specificity, and 8 false negative results (including 4 ACCs). When used in conjunction with other clinical assessments, 18F-FDG-PET/CT can be a valuable tool in evaluating adrenal masses in noncancer patients.

Age-related changes of standardized uptake values in the blood pool and liver: a decade-long retrospective study of the outcomes of 2,526 subjects.

Background activity on fluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) is often used as a reference to assess a patient's response to tumor treatment. To produce a suitable background activity reference, we examined the variations in standardized uptake values (SUVs) in the blood pool and liver of a large multi-aged population. A total of 2,526 subjects underwent 18F-FDG PET/CT examinations and were divided into 12 age groups. Pearson's partial correlation and multivariate regression analyses were performed to assess the associations between individual factors and SUVs of the blood pool and liver and to identify the factor that most influenced the SUVs. The mean SUVs across the age groups were also determined. Positive correlations were found between individual factors and SUVs. Age appeared to be the most important predictor of SUVs and was significantly associated with the blood pool SUVmax (ß=0.466, P=0.000), blood pool SUVmean (ß=0.393, P=0.000), liver SUVmax (ß=0.347, P=0.000), and liver SUVmean (ß=0.354, P=0.000). Blood pool and liver SUVs rose rapidly until the age of 20 and then showed a slow upward trend without reaching a plateau. Age is an important factor that influences variations in the blood pool and liver SUVs. Our study clarified this understanding of age-related variations in SUVs and provided a normal range of blood pool and liver SUVs that may aid clinicians in evaluating tumors with greater accuracy.

18F-FDG uptake as a predictive factor for progressive aortic enlargement in aortic dissection.

Progressive aortic enlargement (PAE) is a critical adverse event in patients with medically treated aortic dissection (AD). However, no reliable predictor of the PAE has been established. The purpose of this study was to evaluate the value of 18F-FDG PET/CT for the prediction of PAE in patients with medically treated AD. Sixteen patients with AD who underwent optimal medical therapy were enrolled. 18F-FDG PET/CT examinations were performed in subacute phase (2weeks-3months) after the onset of AD. Target-to-background ratio (TBR) was measured as the maximum standardized uptake value (SUV) in the dissected aortic wall divided by blood pool SUV. The relation between TBR and occurrence of PAE (> 10mm/year) was evaluated. PAE was observed in four patients during the median follow-up period of 24months. The TBR measured in the 4 patients showing PAE was significantly higher than that in the remaining 12 patients without PAE (2.44 ± 0.56 vs 1.87 ± 0.33, P = 0.025). The area under the receiver operating characteristic curve of TBR for predicting PAE was 0.82. With a threshold of 2.34, the TBR showed the sensitivity, specificity, and positive and negative predictive value of 75%, 92%, 75%, and 92%, respectively, for the prediction of PAE. Higher 18F-FDG uptake in the dissected aortic wall as determined by TBR is associated with increased risk of PAE in patients with medically treated AD. TBR shows good specificity and negative predictive value for predicting PAE.

89Zr-labeled Bispecific T-cell Engager AMG 211 PET Shows AMG 211 Accumulation in CD3-rich Tissues and Clear, Heterogeneous Tumor Uptake.

Biodistribution of bispecific antibodies in patients is largely unknown. We therefore performed a feasibility study in 9 patients with advanced gastrointestinal adenocarcinomas to explore AMG 211 biodistribution (also known as MEDI-565), an approximately 55 kDa bispecific T-cell engager (BiTE®) directed against carcinoembryonic antigen (CEA) on tumor cells and cluster of differentiation 3 (CD3) on T-cells. 89Zr-labeled AMG 211 as tracer was administered alone or with cold AMG 211, for PET imaging before and/or during AMG 211 treatment. Before AMG 211 treatment, the optimal imaging dose was 200-μg 89Zr-AMG 211 + 1,800-μg cold AMG 211. At 3 hours, the highest blood pool standardized uptake value (SUV)mean was 4.0, and tracer serum half-life was 3.3 hours. CD3-mediated uptake was clearly observed in CD3-rich lymphoid tissues including spleen and bone marrow (SUVmean 3.2 and 1.8, respectively), and the SUVmean decreased more slowly than in other healthy tissues. 89Zr-AMG 211 remained intact in plasma and was excreted predominantly via the kidneys in degraded forms. Of 43 visible tumor lesions, 37 were PET quantifiable, with a SUVmax of 4.0 [interquartile range (IQR) 2.7-4.4] at 3 hours using the optimal imaging dose. The tracer uptake differed between tumor lesions 5-fold within and 9-fold between patients. During AMG 211 treatment, tracer was present in the blood pool, whereas tumor lesions were not visualized, possibly reflecting target saturation. This first-in-human study shows high, specific 89Zr-AMG 211 accumulation in CD3-rich lymphoid tissues, as well as a clear, inter- and intraindividual heterogeneous tumor uptake.

Tissue standardized uptake value is a closer surrogate of blood fluorine-18 fluorodeoxyglucose clearance after division by blood standardized uptake value, illustrated in brain and liver

The numerator and denominator of the left-hand side of the Gjedde-Patlak-Rutland (GPR) equation for measurement of blood fluorine-18 fluorodeoxyglucose (F-FDG) clearance into tissue (Ki) are the standardized uptake values (SUVs) of tissue and blood, respectively. The extent to which normalized time (NT) in the GPR equation exceeds real time depends on half-time of clearance of F-FDG from blood. A literature review shows that NT is fairly constant, about 100 min at 60 min postinjection of F-FDG, in keeping with our own finding of no significant difference in maximum SUV in blood 60 min postinjection of F-FDG between 39 patients with F-FDG-avid malignancy on routine PET/CT (1.74±0.31) and 21 patients with normal PET/CT (1.79±0.32), and similar blood glucose levels (BGLs). Volume of distribution (V0) in the GPR equation is ∼0.4 ml/ml for brain and ∼0.9 ml/ml for lean liver. Using these values of V0 and an NT of 100 min, we used the GPR equation to calculate Ki from our own published values of SUVliver/SUVblood and SUVbrain/SUVblood at 60 min postinjection, obtaining 0.0045 ml/min/ml for liver and 0.036 ml/min/ml for brain at BGL of 5 mmol/l. These values for Ki at this BGL are close to literature values of Ki, which for liver and brain are ∼0.0033 and ∼0.035 ml/min/ml, respectively. We conclude, therefore, that following division with blood pool SUV, tissue SUV becomes a closer surrogate of Ki. This division also eliminates the controversy over which whole body metric to use in the calculation of SUV.

Prognostic Value of Tumor-to-Blood Standardized Uptake Ratio in Patients with Resectable Non-Small-Cell Lung Cancer

Previously published studies showed that the standard tumor-to-blood standardized uptake value (SUV) ratio (SUR) was a more accurate prognostic method than tumor maximum standardized uptake value (SUVmax). This study evaluated and compared prognostic value of positron emission tomography (PET) parameters and normalized value of PET parameters by blood pool SUV in non-small-cell lung cancer (NSCLC) patients who received curative surgery. Seventy-seven patients who underwent curative resection for NSCLC between January 2010 to December 2013 were enrolled in this study. 18Fluorine-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) was performed before surgery. The mean standardized uptake value (SUVmean), SUVmax, metabolic tumor volume (MTV), and total lesion glycolysis (TLG) of each lesion was measured, on the workstation. SURmean, SURmax, and TLGSUR were calculated by dividing each of them by descending aorta SUVmean. Cox proportional hazards regression was used to analyze the effect of age, sex, pathological parameters, and PET parameters on recurrence and death. In Cox regression analysis, N stage predicted for both recurrence (p < 0.0001) and death (p < 0.0001). SURmax predicted recurrence (p = 0.0014), not death. Area under the receiver operating characteristic curve of SURmax was 0.759 with cutoff value 4.004. However, SUVmax, SUVmean, MTV, TLG, SURmean, and TLGSUR predicted neither recurrence nor death. Among PET parameters, SURmax was the independent predictor of recurrence in NSCLC patients who received curative surgery. N stage was the independent prognostic factor for both recurrence and death. Both parameters could be used to stratify the risk of NSCLC patients.

Reference Range for Intrapatient Variability in Blood-Pool and Liver SUV for 18F-FDG PET

(18)F-FDG PET qualitative tumor response assessment or tumor-to-background ratios compare targets against blood-pool or liver activity; standardized uptake value (SUV) semiquantitation has artifacts and is validated by a stable normal-tissue baseline. The aim of this study was to document the normal intrapatient range of scan-to-scan variation in blood-pool SUV and liver SUV and to identify factors that may adversely affect it (increase its spread). Between July 2009 and June 2010, 132 oncology patients had 2 PET/CT scans. Patient preparation, acquisition, and reconstruction protocols were held stable, uniform, and reproducible. Mean SUV (body weight) values were obtained from 2-dimensional regions of interest in the aortic arch blood pool and in the right lobe of the liver. Of the 132 patients, 65 had lymphoma. Their mean age was 62.5 y. The group's mean serum glucose level was 6.0 mmol/L at the first visit and 5.9 mmol/L at the second visit. The mean (18)F-FDG dose was 4.1 MBq/kg at the first visit and 4.0 at the second. At the first visit, the group's mean blood-pool SUV was 1.55 (SD, 0.38); at the second, 1.58 (SD, 0.37)-not statistically different. The group's mean liver SUV was 2.17 (SD, 0.44) at the first visit and 2.29 (SD, 0.44) at the second (P = 0.005). Visit-to-visit intrapatient variation in blood-pool and liver SUVs had gaussian distributions. The variation in blood-pool SUV had a mean of 0.03 and SD of 0.42. The variation in liver SUV had a mean of 0.12 and SD of 0.50. Using 95th percentiles, the reference range in our patient population for intrapatient variation was -0.8 to 0.9 for blood pool SUV and -0.9 to 1.1 for liver SUV. Subanalysis by cancer type and chemotherapy suggested that the rise in liver SUV between the 2 visits was largely due to the commencement of chemotherapy, but no factors were identified as systematically affecting intrapatient variation, and no factors were identified as increasing its spread. In our patient cohort, the reference range for intrapatient variation in blood-pool and liver SUVs is -0.8 to 0.9 and -0.9 to 1.1, respectively.

Quantification of Atherosclerotic Plaque Activity and Vascular Inflammation using [18-F] Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography (FDG-PET/CT)

Conventional non-invasive imaging modalities of atherosclerosis such as coronary artery calcium (CAC) and carotid intimal medial thickness (C-IMT) provide information about the burden of disease. However, despite multiple validation studies of CAC, and C-IMT, these modalities do not accurately assess plaque characteristics, and the composition and inflammatory state of the plaque determine its stability and, therefore, the risk of clinical events. [(18)F]-2-fluoro-2-deoxy-D-glucose (FDG) imaging using positron-emission tomography (PET)/computed tomography (CT) has been extensively studied in oncologic metabolism. Studies using animal models and immunohistochemistry in humans show that FDG-PET/CT is exquisitely sensitive for detecting macrophage activity, an important source of cellular inflammation in vessel walls. More recently, we and others have shown that FDG-PET/CT enables highly precise, novel measurements of inflammatory activity of activity of atherosclerotic plaques in large and medium-sized arteries. FDG-PET/CT studies have many advantages over other imaging modalities: 1) high contrast resolution; 2) quantification of plaque volume and metabolic activity allowing for multi-modal atherosclerotic plaque quantification; 3) dynamic, real-time, in vivo imaging; 4) minimal operator dependence. Finally, vascular inflammation detected by FDG-PET/CT has been shown to predict cardiovascular (CV) events independent of traditional risk factors and is also highly associated with overall burden of atherosclerosis. Plaque activity by FDG-PET/CT is modulated by known beneficial CV interventions such as short term (12 week) statin therapy as well as longer term therapeutic lifestyle changes (16 months). The current methodology for quantification of FDG uptake in atherosclerotic plaque involves measurement of the standardized uptake value (SUV) of an artery of interest and of the venous blood pool in order to calculate a target to background ratio (TBR), which is calculated by dividing the arterial SUV by the venous blood pool SUV. This method has shown to represent a stable, reproducible phenotype over time, has a high sensitivity for detection of vascular inflammation, and also has high inter-and intra-reader reliability. Here we present our methodology for patient preparation, image acquisition, and quantification of atherosclerotic plaque activity and vascular inflammation using SUV, TBR, and a global parameter called the metabolic volumetric product (MVP). These approaches may be applied to assess vascular inflammation in various study samples of interest in a consistent fashion as we have shown in several prior publications.

A Positron Emission Tomography/Computed Tomography (PET/CT) Evaluation of Asymptomatic Abdominal Aortic Aneurysms: Another Point of View

To assess the prevalence of increased (18)F-fluorodeoxyglucose (FDG) uptake in aneurysmal walls, adopting a case-control approach in a population of asymptomatic patients with abdominal aortic aneurysm (AAA). This study included 40 males (mean age: 74 years, range: 59-93 years), consecutive, white Caucasian patients, with asymptomatic infrarenal AAA. The mean diameter of AAA was 4.9 cm (range: 4.8-5.4 cm), detected by computed tomography (CT) scan. Control Subjects: 44 age-matched controls subjects (mean age: 71 years, range: 59-85 years, 24 males, 20 females) who were selected according to a case-control criterion among a population of patients without any clinical evidence of atherosclerotic disease. Patients and controls underwent simultaneous FDG-positron emission tomography (PET) and CT imaging from the skull base to the femoral neck by using an integrated PET/CT scanner. PET/CT studies were analysed both visually and quantitatively. For quantitative analysis, circular CT-based regions of interest (ROIs) were drawn on the AAA, on all the aortic segments, and on the large vessel included in the study (carotid, subclavian, and iliac arteries). FDG uptake was quantified by calculating the mean and maximum standardized uptake values (SUVs) within each ROI and normalizing for the blood-pool SUV to obtain the final target-to-background ratio. Arterial calcium load was graded according to a semiquantitative five-point scale based on calcification of the arterial ring. Metabolic activity in the aneurysmal aortic segment was even lower with respect to both the adjacent--nonaneurysmal--samples of patient group and the corresponding arterial segments of control subjects (P < 0.001 and P < 0.01, respectively). In visual analysis, no patients showed an increased focal uptake of degree adequate to identify the aneurysmal arterial wall. AAA patients showed significantly higher values of total calcium load (ACL) than controls in ascending aorta and subclavian and iliac arteries (P < 0.01), and only in AAA patient group, a significant correlation was present between values of ACL in both iliac arteries and abdominal aorta on one side and wall metabolic activity in the same arteries on the other (P < 0.05). In conclusion, our results suggest that FDG hot spot, as well an increased diffuse uptake of FDG, in PET/CT studies is an extremely rare finding in patients with AAA of diameter close to surgical indications.

18F-FDG PET/CT Identifies Patients at Risk for Future Vascular Events in an Otherwise Asymptomatic Cohort with Neoplastic Disease

Our objective was to evaluate the association of arterial (18)F-FDG uptake and calcifications in large arteries as detected by (18)F-FDG PET/CT with the subsequent occurrence of vascular events in otherwise asymptomatic cancer patients. Clinical follow-up information was obtained for 932 cancer patients examined with whole-body (18)F-FDG PET/CT (median follow-up time, 29 mo). Among this cohort, 279 patients had died from their oncologic disease. In 15 of 932 patients (1.6%), a vascular event, defined as ischemic stroke, myocardial infarction, or revascularization, was registered. The maximal standardized uptake value (SUV) was divided by the blood-pool SUV, yielding a target-to-background ratio (TBR) for each arterial segment. The mean TBR as well as a calcified plaque sum score per patient were calculated in the major vessels: ascending, descending, and abdominal aorta, aortic arch, as well as iliac and carotid arteries. A significant correlation was observed between mean TBR and calcified plaque sum (P < 0.001). Although calcified plaque sum significantly correlated with all conventional risk factors for vascular events, mean TBR correlated only with age, the male sex, and hypertension. The Cox regression hazard model identified a mean TBR >or= 1.7 and a calcified plaque sum >or= 15 as independent predictors for the occurrence of a vascular event. Patients with both mean TBR and calcified plaque sum above these thresholds were identified as having the highest risk for a future vascular event. However, a mean TBR >or= 1.7 had greater prognostic value than did a calcified plaque sum >or= 15. In a large cohort of cancer patients, increased (18)F-FDG uptake in major arteries emerged as the strongest predictor of a subsequent vascular event. Concomitant severe vascular calcifications seemed to impart a particularly high risk. Given the small event rate in the present study, larger, prospective trials of patients without cancer are required to substantiate these promising results.