Purpose: To study blood flow (BF) and metabolism in normal pancreas and in different pancreatic lesions. We then determined the effect of these biomarkers on outcome in patients with pancreatic cancer. Experimental Design: Oxygen-15-labeled water and fluorodeoxyglucose positron emission tomography/computed tomography scans were used in 26 patients with a suspicion of pancreatic cancer to measure pancreatic BF and metabolism. In addition, the ratio of standardized uptake value to BF (SUV/BF) was calculated. Patients were divided into three groups: patients with a finding of normal pancreas (n = 7), benign lesions (n = 8), and malignant tumors (n = 11). Results: Patients with benign and malignant pancreatic tumors had decreased BF of the lesion by 48% and 60%, respectively, compared with patients with normal pancreatic tissue. SUV max was 3-fold higher in malignant tumors compared with both benign lesions and normal pancreas (P < 0.05). In contrast, the SUV max of patients with benign lesions and normal pancreas did not differ. The SUV/BF ratio was significantly higher in malignant lesions than in benign lesions or in patients with normal pancreas (P < 0.05). In patients with cancer, high SUV/BF ratio was a stronger predictor of poor survival compared with high metabolism or lower-than-normal pancreatic BF. Conclusions: BF in pancreatic cancer is significantly reduced compared with the normal pancreas, which may in part explain the poor success of both radiotherapy and chemotherapy. We suggest that the composite measurement of BF and metabolism in pancreatic cancer could serve as a novel tool in the planning of treatments targeting vasculature. (Clin Cancer Res 2009;15(17):5511-7)

Previous human studies have shown divergent results concerning the effects of exercise training on myocardial blood flow (MBF) at rest or during adenosine-induced hyperaemia in humans. We studied whether these responses are related to alterations in adenosine A 2A receptor (A 2A R) density in the left-ventricular (LV) myocardium, size and work output of the athlete's heart, or to fitness level. MBF at baseline and during intravenous adenosine infusion, and A 2A R density at baseline were measured using positron emission tomography, and by a novel A 2A R tracer in 10 healthy male endurance athletes (ET) and 10 healthy untrained (UT) men. Structural LV parameters were measured with echocardiography. LV mass index was 71% higher in ET than UT (193 ± 18 g m −2 versus 114 ± 13 g m −2 , respectively). MBF per gram of tissue was significantly lower in the ET than UT at baseline, but this was only partly explained by reduced LV work load since MBF corrected for LV work was higher in ET than UT, as well as total MBF. The MBF during adenosine-induced hyperaemia was reduced in ET compared to UT, and the fitter the athlete was, the lower was adenosine-induced MBF. A 2A R density was not different between the groups and was not coupled to resting or adenosine-mediated MBF. The novel findings of the present study show that the adaptations in the heart of highly trained endurance athletes lead to relative myocardial 'overperfusion' at rest. On the other hand hyperaemic perfusion is reduced, but is not explained by A 2A R density.

The simulation study suggested that delay and dispersion time constants should be estimated within an accuracy of 2 s. V(A) and p cannot be neglected or fixed, and reliable measurement of even relative RBF values requires that V(A) is fitted. This study showed the feasibility of measurement of RBF using PET with H(2)(15)O.

Our data support the notion of former clinical trials that angiographic severity of RAS does not determine the response to revascularization. Quantitative PET perfusion imaging is a promising tool to noninvasively measure renal perfusion for the assessment of physiological impact of RAS.

BackgroundMicrovascular function plays an important role in ARVD (atherosclerotic renovascular disease). RFR (renal flow reserve), the capacity of renal vasculature to dilate, is known to reflect renal microvascular function. In this pilot study, we assessed PET (positron emission tomography)-based RFR values of healthy persons and renal artery stenosis patients.Seventeen patients with ARVD and eight healthy subjects were included in the study. Intravenous enalapril 1 mg was used as a vasodilatant, and the maximum response (blood pressure and RFR) to it was measured at 40 min. Renal perfusion was measured by means of oxygen-15-labeled water PET. RFR was calculated as a difference of stress flow and basal flow and was expressed as percent [(stress blood flow − basal blood flow)/basal blood flow] × 100%.ResultsRFR of the healthy was 22%. RFR of the stenosed kidneys of bilateral stenosis patients (27%) was higher than that of the stenosed kidneys of unilateral stenosis patients (15%). RFR of the contralateral kidneys of unilateral stenosis patients was 21%. There was no difference of statistical significance between RFR values of ARVD subgroups or between ARVD subgroups and the healthy. In the stenosed kidneys of unilateral ARVD patients, stenosis grade of the renal artery correlated negatively with basal (p = 0.04) and stress flow (p = 0.02). Dispersion of RFR values was high.ConclusionsThis study is the first to report [15O]H2O PET-based RFR values of healthy subjects and ARVD patients in humans. The difference between RFR values of ARVD patients and the healthy did not reach statistical significance perhaps because of high dispersion of RFR values. [15O]H2O PET is a valuable non-invasive and quantitative method to evaluate renal blood flow though high dispersion makes imaging challenging. Larger studies are needed to get more information about [15O]H2O PET method in evaluation of renal blood flow.

Subcutaneous adipose tissue blood flow is finely regulated, and tuned with fat metabolism; little is known about visceral fat, which is less accessible in humans. In estimating blood flow with positron emission tomography (PET) and oxygen-15-labelled water ([ 15 (FBP). Location, diameter, and inner radioactivity levels of the abdominal aorta were automatically determined. Image derived arterial curves (IDI) were compared to measured arterial blood data, as obtained by an online blood sampler (OSI). Blood flow in three adipose tissue depots was estimated using the autoradiographic method with OSI vs the FBP image derived input (F-IDI) function. Correlations between blood flow results obtained with OSI and IDI were significant (r 0.87, p<0.0001) in all regions. Estimates of the aortic diameter ranged between 10.7-17.2 mm. A good agreement was found between area under the curve (AUC) values of F-IDI and OSI curves; the AUC F-IDI /AUC OSI ratio was 0.97±0.10. Our results support the implementation of the current method for the non-invasive detection of the abdominal aorta input function from a dynamic [15 O]H 2 O PET image in the quantification of regional blood flow in low flow tissues. This method allows simultaneously examine subcutaneous and intraabdominal fat depots.

<div>Abstract<p><b>Purpose:</b> To study blood flow (BF) and metabolism in normal pancreas and in different pancreatic lesions. We then determined the effect of these biomarkers on outcome in patients with pancreatic cancer.</p><p><b>Experimental Design:</b> Oxygen-15–labeled water and fluorodeoxyglucose positron emission tomography/computed tomography scans were used in 26 patients with a suspicion of pancreatic cancer to measure pancreatic BF and metabolism. In addition, the ratio of standardized uptake value to BF (SUV/BF) was calculated. Patients were divided into three groups: patients with a finding of normal pancreas (<i>n</i> = 7), benign lesions (<i>n</i> = 8), and malignant tumors (<i>n</i> = 11).</p><p><b>Results:</b> Patients with benign and malignant pancreatic tumors had decreased BF of the lesion by 48% and 60%, respectively, compared with patients with normal pancreatic tissue. SUV_max was 3-fold higher in malignant tumors compared with both benign lesions and normal pancreas (<i>P</i> < 0.05). In contrast, the SUV_max of patients with benign lesions and normal pancreas did not differ. The SUV/BF ratio was significantly higher in malignant lesions than in benign lesions or in patients with normal pancreas (<i>P</i> < 0.05). In patients with cancer, high SUV/BF ratio was a stronger predictor of poor survival compared with high metabolism or lower-than-normal pancreatic BF.</p><p><b>Conclusions:</b> BF in pancreatic cancer is significantly reduced compared with the normal pancreas, which may in part explain the poor success of both radiotherapy and chemotherapy. We suggest that the composite measurement of BF and metabolism in pancreatic cancer could serve as a novel tool in the planning of treatments targeting vasculature. (Clin Cancer Res 2009;15(17):5511–7)</p></div>

<div>Abstract<p><b>Purpose:</b> To study blood flow (BF) and metabolism in normal pancreas and in different pancreatic lesions. We then determined the effect of these biomarkers on outcome in patients with pancreatic cancer.</p><p><b>Experimental Design:</b> Oxygen-15–labeled water and fluorodeoxyglucose positron emission tomography/computed tomography scans were used in 26 patients with a suspicion of pancreatic cancer to measure pancreatic BF and metabolism. In addition, the ratio of standardized uptake value to BF (SUV/BF) was calculated. Patients were divided into three groups: patients with a finding of normal pancreas (<i>n</i> = 7), benign lesions (<i>n</i> = 8), and malignant tumors (<i>n</i> = 11).</p><p><b>Results:</b> Patients with benign and malignant pancreatic tumors had decreased BF of the lesion by 48% and 60%, respectively, compared with patients with normal pancreatic tissue. SUV_max was 3-fold higher in malignant tumors compared with both benign lesions and normal pancreas (<i>P</i> < 0.05). In contrast, the SUV_max of patients with benign lesions and normal pancreas did not differ. The SUV/BF ratio was significantly higher in malignant lesions than in benign lesions or in patients with normal pancreas (<i>P</i> < 0.05). In patients with cancer, high SUV/BF ratio was a stronger predictor of poor survival compared with high metabolism or lower-than-normal pancreatic BF.</p><p><b>Conclusions:</b> BF in pancreatic cancer is significantly reduced compared with the normal pancreas, which may in part explain the poor success of both radiotherapy and chemotherapy. We suggest that the composite measurement of BF and metabolism in pancreatic cancer could serve as a novel tool in the planning of treatments targeting vasculature. (Clin Cancer Res 2009;15(17):5511–7)</p></div>