Alignment of 3-dimensional cardiac structures in O-15-labeled water PET emission images with mutual information.

BACKGROUND: The aim of this study was to develop a method to correct the heart position between two oxygen 15-labeled water cardiac positron emission tomography (PET) image sets to be able to use the equivalent regions of interest for the quantification of the perfusion values in the same myocardial segments. METHODS AND RESULTS: Independent component analysis was applied to the dynamic image sets (simulated phantom and 6 rest-pharmacologic stress and 10 rest-rest image sets of healthy female volunteers) acquired at different time points to separate the cardiac structures (ventricles and myocardium). The separated component images from independent component analysis from the 2 studies of the same individual were aligned with a normalized mutual information-based registration method. The alignment parameters were applied to position the regions of interest in the floating image sets for calculation of the myocardial blood flow values. In the rest case the mean myocardial blood flow value was 0.76 +/- 0.12 mL x g(-1) x min(-1) for the manual method and 0.79 +/- 0.10 mL x g(-1) x min(-1) for the proposed method (by use of the right ventricle component in the alignment), and in the stress case these values were 3.39 +/- 0.70 mL x g(-1) x min(-1) and 4.01 +/- 0.71 mL x g(-1) x min(-1), respectively. No statistically significant difference was found between the methods. CONCLUSION: In the tests with the phantom and patient images the alignment of cardiac structures was shown to be successful. The alignment could be done without the use of information from the myocardial compartment.     

Exhaled nitric oxide and its long‐term variation in healthy non‐smoking subjects

Exhaled nitric oxide (NOexp) is an indicator of inflammation in the airways. Reference values obtained from healthy adults or information on long‐term variation of NOexp are not yet available. The aims of this pilot study were to collect values of NOexp from a selected group of healthy adults and to assess their long‐term variation. We studied 26 healthy subjects (age 21–48, 16 male, 10 female) with normal findings in flow‐volume spirometry, pulmonary diffusing capacity, relative amount of blood eosinophils, chest X‐ray and ECG at rest. NOexp was determined according to the European Respiratory Society guidelines during slow expiration against an airflow resistance. The measurements were repeated after 7 (n=13) and 23 days (n=17). The mean value of NOexp (n=26) was 6·9 ng g^–1 (95% confidence interval, 6·0–7·9 ng g^–1). The upper limit of intra‐individual variation (+2 SD) was 11·9 ng g^–1 and the lower limit (–2 SD) 1·9 ng g^–1, respectively. The mean (SD) value of NO production (NO output) was 39·1 pmol s^–1 (20 pmol s^–1). We found no correlation between NOexp and age (r=–0·06, P=0·78) and no association of NOexp with the gender (male vs. female, P=0·40). The intraindividual coefficient of variation (CoV) was 15·8% of NOexp and 20·7% of NO output within the interval of 7 days. CoV was 16·8% of NOexp and 18% of NO output within the interval 23 days. The results suggest that NOexp values over 12 ng g^–1 are abnormally high in healthy subjects. According to the results the change of NOexp by 30–35% or more within the interval of 1–3 weeks would be abnormal.     

Image technique optimization in MR imaging of a titanium alloy joint prosthesis

The purpose of this study was to explore systematically the effect of the imaging parameters changeable by the user in spin-echo (SE) imaging sequences to minimize image distortion when imaging joint prostheses. A titanium alloy hip joint prosthesis was studied at 1.0 T. The SE imaging parameters were bandwidth/pixel (BW/p), TE, strength of encoding gradients (matrix size), echo train length (ETL), and direction of phase and frequency encoding. The effect of ETL in rapid acquisition relaxation enhanced (RARE) sequences was also evaluated with a turbo-SE sequence using a different ETL with the same TR and an effective TE. It is concluded that an optimized image quality can be achieved in SE imaging by using a high bandwidth/pixel value (at least 130 Hz/pixel), a high resolution matrix (256–512), sequences with multiple refocusing, and a frequency-encoding axis parallel to the long axis of the prosthesis. The degree of distortion is reduced with this optimized technique.     

Operative versus closed treatment of primary dislocation of the patella Similar 2-year results in 125 randomized patients

To assess whether initial surgery is beneficial for patients with primary dislocation of the patella, we carried out a prospective randomized study. Knee stability was examined under anesthesia, and associated injuries were excluded by diagnostic arthroscopy. 55 patients then had closed treatment and 70 patients were operated on with individually adjusted proximal realignment procedures.

Surgery gave no benefit based on 2 years of follow-up. The subjective result was better in the non-operative group in respect of mean Houghston VAS knee score (closed 90, operative 87), but similar in terms of the patient's own overall opinion and mean Lysholm II knee score. Recurrent instability episodes (redislocation or recurrent subluxation) occurred in 20 nonoperated and in 18 operated patients. Of these, 15 and 12, respectively, then suffered redislo-cations. Function was better after closed treatment. Serious complications occurred after surgery in 4 patients.

In conclusion, the recurrence of patellar dislocation may be more frequent than reported, whatever the form of treatment. Routine operative management cannot be recommended for primary dislocation of the patella.     

Binding of serotonergic ligands to brain membranes of alcohol-preferring AA and alcohol-avoiding ANA rats.

The alcohol-preferring AA rats have higher concentration of 5-hydroxytryptamine (5-HT) in the brain than the alcohol-avoiding ANA rats. In the present study, the 5-HT1, 5-HT2, and 5-HT3 receptors were studied with [3H]5-HT, [3H]ketanserin, and [3H]LY278584, respectively, in membrane homogenates from different brain regions of both rat lines using in vitro binding assays. No differences in the 5-HT1 and 5-HT2 receptor binding in the brainstem, hippocampus, frontal cortex, and hypothalamus or in the 5-HT3 receptor binding in the nucleus accumbens, amygdala, hippocampus, and frontal cortex were observed between the ethanol-naive animals of the rat lines. In rats given the opportunity to voluntarily consume alcohol, there was a tendency to increase 5-HT1 binding in the ANA rats, which tendency was, however, also found in their ethanol-naive controls subjected to the same handling and behavioral tests as the ethanol-experienced animals. The results do not, however, indicate that any genetic modifications of the 5-HT receptor-binding sites have occurred in the process of the selective breeding of AA and ANA rats for alcohol preference and avoidance, respectively.     

Effect of Vigabatrin on the Electroencephalogram in Rats

Vigabatrin (gamma-vinyl GABA; GVG) is a new antiepileptic drug (AED) that increases the level of the inhibitory transmitter, gamma-aminobutyric acid (GABA) in the brain. We evaluated the effect of GVG on the EEG of normal rats. GVG was administered intraperitoneally (i.p.) at a dose of 100 mg/kg once a day for 12 days. EEG was recorded at baseline, on the fourth day, at the end of the 12-day GVG period and 10 days after discontinuation of GVG. GVG increased the amplitude of delta (1-4 Hz) and theta (4-8 Hz) frequency bands and resulted in slowing of the peak frequency (Fp) and mean frequency (Fm) in both the frontal and occipital cortex, especially during waking-immobility. EEG changes normalized within 10 days after the last GVG injections. The results suggest that a relationship may exist between the EEG changes and increase in GABA levels with GVG.     

The future of cardiovascular imaging and non-invasive diagnosis

Advances in medical imaging now make it possible to investigate any patient with cardiovascular disease using multiple methods which vary widely in their technical requirements, benefits, limitations and costs. The appropriate use of alternative tests requires their integration into joint clinical diagnostic services where experts in all methods collaborate. This statement summarises the principles that should guide developments in cardiovascular diagnostic services.This paper is published simultaneously in the European Heart Journal (2006;27:1750–1753) and in the European Journal of Echocardiography (2006;7:268–273).     

18F-FDG assessment of glucose disposal and production rates during fasting and insulin stimulation: a validation study.

The glucose analog (18)F-FDG is commonly used to quantify regional glucose uptake in vivo. The aim of this study was to test whether the analysis of plasma (18)F-FDG kinetics could be used to estimate endogenous glucose production (EGP) and the total rate of appearance (Ra), total rate of disappearance (Rd), and the metabolic clearance rate (MCR) of glucose. METHODS: Fourteen pigs were coinjected with (18)F-FDG and 6,6-(2)H-glucose ((2)H-G) during fasting (n = 6) and during physiologic (1.0 mU.kg(-1).min(-1), n = 4) and supraphysiologic (5.0 mU.kg(-1).min(-1), n = 4) euglycemic hyperinsulinemia. Arterial plasma was sampled for 180 min to quantify the parameters for the 2 tracers. RESULTS: Fasting Rd((2))(H-G) and Rd(FDG) were 12.3 +/- 2.1 and 13.3 +/- 1.3 micromol.kg(-1).min(-1) (difference not statistically significant [NS]). M values were more than doubled between the 2 clamp studies (P < 0.0001). Rd((2))(H-G) and Rd(FDG) were dose-dependently higher during the hyperinsulinemic state (19.8 +/- 3.7 vs. 18.9 +/- 1.1 and 31.4 +/- 4.1 vs. 31.9 +/- 2.3 in 1.0 and 5.0 mU.kg(-1).min(-1) studies, respectively; difference between tracers NS) than during the fasting state, with a parallel suppression of EGP((2))(H-G) and EGP(FDG). Parameters estimated by (18)F-FDG and (2)H-G were equivalent in all groups; their agreement was confirmed by Bland-Altman examination. Total Rd(FDG) correlated with Rd((2))(H-G) (r = 0.74; P = 0.003), M (r = 0.92; P = 0.001), MCR((2))(H-G) (r = 0.52; P = 0.037), and EGP((2))(H-G) (r = -0.71; P = 0.004). EGP(FDG) correlated with EGP((2))(H-G) (r = 0.62; P = 0.018), Rd((2))(H-G) (r = -0.78; P = 0.001), and MCR((2))(H-G) (r = -0.67; P = 0.008). The (18)F-FDG mean transit time correlated inversely with the M and Rd values and positively with EGP. CONCLUSION: The glucose analog (18)F-FDG can be used in the simultaneous estimation of whole-body glucose turnover and production and regional (18)F-FDG PET measurements under both fasting and insulin-stimulated conditions.