High-resolution motion compensated MRA in patients with congenital heart disease using extracellular contrast agent at 3 Tesla.

BACKGROUND: Using first-pass MRA (FP-MRA) spatial resolution is limited by breath-hold duration. In addition, image quality may be hampered by respiratory and cardiac motion artefacts. In order to overcome these limitations an ECG- and navigator-gated high-resolution-MRA sequence (HR-MRA) with slow infusion of extracellular contrast agent was implemented at 3 Tesla for the assessment of congenital heart disease and compared to standard first-pass-MRA (FP-MRA). METHODS: 34 patients (median age: 13 years) with congenital heart disease (CHD) were prospectively examined on a 3 Tesla system. The CMR-protocol comprised functional imaging, FP- and HR-MRA, and viability imaging. After the acquisition of the FP-MRA sequence using a single dose of extracellular contrast agent the motion compensated HR-MRA sequence with isotropic resolution was acquired while injecting the second single dose, utilizing the timeframe before viability imaging. Qualitative scores for image quality (two independent reviewers) as well as quantitative measurements of vessel sharpness and relative contrast were compared using the Wilcoxon signed-rank test. Quantitative measurements of vessel diameters were compared using the Bland-Altman test. RESULTS: The mean image quality score revealed significantly better image quality of the HR-MRA sequence compared to the FP-MRA sequence in all vessels of interest (ascending aorta (AA), left pulmonary artery (LPA), left superior pulmonary vein (LSPV), coronary sinus (CS), and coronary ostia (CO); all p < 0.0001). In comparison to FP-MRA, HR-MRA revealed significantly better vessel sharpness for all considered vessels (AA, LSPV and LPA; all p < 0.0001). The relative contrast of the HR-MRA sequence was less compared to the FP-MRA sequence (AA: p <0.028, main pulmonary artery: p <0.004, LSPV: p <0.005). Both, the results of the intra- and interobserver measurements of the vessel diameters revealed closer correlation and closer 95 % limits of agreement for the HR-MRA. HR-MRA revealed one additional clinical finding, missed by FP-MRA. CONCLUSIONS: An ECG- and navigator-gated HR-MRA-protocol with infusion of extracellular contrast agent at 3 Tesla is feasible. HR-MRA delivers significantly better image quality and vessel sharpness compared to FP-MRA. It may be integrated into a standard CMR-protocol for patients with CHD without the need for additional contrast agent injection and without any additional examination time.

Comparative evaluation of the immunogenicity of combined hepatitis A and B vaccine by a prospective and retrospective trial.

In the past, immunogenicity of hepatitis A and B vaccines needed to be questioned in persons of advanced age, especially in those of 40 years and older. We performed a comparative multicenter prospective and retrospective study with the combined hepatitis A and B vaccine Twinrix to identify factors influencing the results of the vaccination in a population of all age groups. Out of 489 subjects enrolled, 241 were vaccinated in a prospective study (group 1) and 248 subjects in a retrospective study (group 2) in 17 German centers with median age of 40.1 (14-79) years. Following three applications of the combined hepatitis A/B vaccine we found 96.2% with protective antibodies against HAV and 88.7% were protected against HBV. With increasing age the subjects developed decreasing anti-HBs antibody levels whereas the seroprotection rate was significantly reduced by age (p < 0.05) in the retrospective study group only. Subjects with arterial hypertension and thyroid disease showed significantly decreased protection rates. The timing of the HBV antibody control seems to be important especially in low-responders because protective antibodies may drop below the detection limit within some month. The combined hepatitis A and B vaccine Twinrix proved to be highly effective against HBV, although antibody concentrations and seroprotection rates decreased with increasing age.