[(18)F]FDG-PET is highly effective in assessing the activity and the extent of large-vessel vasculitis. Visual grading was validated as representing the severity of inflammation. Its use is simple and provides high specificity, while high sensitivity is achieved by scanning in the state of active inflammation.

(18)F DOPA PET is highly sensitive and specific for detection of pheochromocytomas and has potential as the functional imaging method of the future.

The introduction of FDG-PET in the diagnostic evaluation of SCLC will improve the staging results and affect patient management, and may reduce the number of tests and invasive procedures.

In heart failure (HF) patients, reflex renal vasoconstriction during exercise is exaggerated. We hypothesized that muscle mechanoreceptor control of renal vasoconstriction is exaggerated in HF. Nineteen HF patients and nineteen controls were enrolled in two exercise protocols: 1) low-level rhythmic handgrip (mechanoreceptors and central command) and 2) involuntary biceps contractions (mechanoreceptors). Renal cortical blood flow was measured by positron emission tomography, and renal cortical vascular resistance (RCVR) was calculated. During rhythmic handgrip, peak RCVR was greater in HF patients compared with controls (37 +/- 1 vs. 27 +/- 1 units; P < 0.01). Change in (Delta) RCVR tended to be greater as well but did not reach statistical significance (10 +/- 1 vs. 7 +/- 0.9 units; P = 0.13). RCVR was returned to baseline at 2-3 min postexercise in controls but remained significantly elevated in HF patients. During involuntary muscle contractions, peak RCVR was greater in HF patients compared with controls (36 +/- 0.7 vs. 24 +/- 0.5 units; P < 0.0001). The Delta RCVR was also significantly greater in HF patients compared with controls (6 +/- 1 vs. 4 +/- 0.6 units; P = 0.05). The data suggest that reflex renal vasoconstriction is exaggerated in both magnitude and duration during dynamic exercise in HF patients. Given that the exaggerated response was elicited in both the presence and absence of central command, it is clear that intact muscle mechanoreceptor sensitivity contributes to this augmented reflex renal vasoconstriction.

18F dopa PET is a promising procedure and useful supplement to morphologic methods in diagnostic imaging of gastrointestinal carcinoid tumors.

Noninvasive PET-measured impaired MBF increases to sympathetic stimulation are associated with the risk of developing cardiovascular events.

Objective-We aimed to evaluate prospectively whether patients with normal coronary angiogram but abnormal epicardial vasoreactivity to cold pressor test (CPT) are at increased risk for cardiovascular events. Methods and Results-Vasoreactivity in response to CPT and dilation of epicardial arteries to intracoronary application of nitroglycerin were assessed quantitatively (percent change of luminal area, ⌬LA%) in 130 patients with normal coronary angiograms. Cardiovascular events (cardiovascular death, acute coronary syndrome, myocardial infarction, percutaneous transluminal coronary angioplasty, coronary bypass grafting, ischemic stroke, or peripheral revascularization) were assessed as clinical outcome parameters over a mean follow-up period of 45Ϯ9 months. Based on their vascular responses to CPT, patients were assigned into the following 3 groups: group 1, patients with normal vasodilator response (⌬LA Ͼ0%; nϭ37); group 2, patients with moderate vasoconstrictor response (⌬LA between 0% and Ϫ15%; nϭ42); and group 3, patients with severe vasoconstrictor response (⌬LA ՅϪ15%; nϭ51). Although patients from groups 2 and 3 had significantly increased vasoconstrictor response to CPT (group 2, ⌬LA Ϫ6Ϯ3% and group 3, ⌬LA Ϫ24Ϯ6% versus group 1, ⌬LA 11Ϯ9%; PՅ0.0001), they showed normal endothelial-independent epicardial vasodilation to intracoronary application of nitroglycerin similar to patients from group 1 (⌬LA 39Ϯ16% and 34Ϯ14% versus 41Ϯ14%; PϭNS, respectively). During follow-up, none of the patients from group 1 developed cardiac events. However, 7 cardiovascular events occurred in group 2 and 30 occurred in group 3 in 4 and 22 patients, respectively (PՅ0.0001, univariate by log-rank test). After adjustment for known risk factors for coronary artery disease, impaired epicardial coronary vasoreactivity to CPT remained significantly associated with the risk of developing cardiovascular events (Pϭ0.040, multivariate by Cox regression model). Key Words: coronary disease Ⅲ C-reactive protein Ⅲ endothelium Ⅲ free radicals Ⅲ prognosis A therosclerotic heart disease is the most prevalent cause of morbidity and mortality in the Western society. 1 It has been realized that the vascular endothelium plays an active and pivotal role in regulating aspects of the integrity and metabolism of the vascular wall, such as vascular structure and permeability, vasomotor tone, and hemostasis. 2 Experimental and clinical studies indicate that the functional integrity of the endothelium implicates antiatherosclerotic and antithrombotic effects. 2,3 Indeed, impaired endothelialdependent vasomotion has been implicated in the development and progression of atherosclerosis. [3][4][5] Clinically, coronary endothelial function can be assessed specifically with the muscarinic, endothelial receptor-mediated vasomotor response to intracoronary infusion of acetylcholine. 2 Moreover, coronary vasoreactivity may be determined by cold pressor test (CPT), which has been shown to induce a complex sympathetic stimulation with a mixed, adrenergic receptor ...

Background —During static exercise in normal healthy humans, reflex renal cortical vasoconstriction occurs. Muscle metaboreceptors contribute importantly to this reflex renal vasoconstriction. In patients with heart failure, in whom renal vascular tone is already increased at rest, it is unknown whether there is further reflex renal vasoconstriction during exercise. Methods and Results —Thirty-nine heart failure patients (NYHA functional class III and IV) and 38 age-matched control subjects (controls) were studied. Renal blood flow was measured by dynamic positron emission tomography. Graded handgrip exercise and posthandgrip ischemic arrest were used to clarify the reflex mechanisms involved. During sustained handgrip (30% maximum voluntary contraction), peak renal vasoconstriction was significantly increased in heart failure patients compared with controls (70±13 versus 42±1 U, P =0.02). Renal vasoconstriction returned to baseline in normal humans by 2 to 5 minutes but remained significantly increased in heart failure patients at 2 to 5 minutes and had returned to baseline at 20 minutes. In contrast, during posthandgrip circulatory arrest, which isolates muscle metaboreceptors, peak renal vasoconstriction was not greater in heart failure patients than in normal controls. In fact, the increase in renal vasoconstriction was blunted in heart failure patients compared with controls (20±5 versus 30±2 U, P =0.05). Conclusions —During sustained handgrip exercise in heart failure, both the magnitude and duration of reflex renal vasoconstriction are exaggerated in heart failure patients compared with normal healthy humans. The contribution of the muscle metaboreceptors to reflex renal vasoconstriction is blunted in heart failure patients compared with normal controls.