Feasibility of electromagnetically guided transjugular intrahepatic portosystemic shunt procedure.

OBJECTIVES: To develop an electromagnetic navigation technology for transjugular intrahepatic portosystemic shunt (TIPS) creation and translate it from phantom to an in-vivo large animal setting. MATERIAL AND METHODS: A custom-designed device for TIPS creation consisting of a stylet within a 5 French catheter as well as a software prototype were developed that allow real-time tip tracking of both stylet and catheter using an electromagnetic tracking system. Feasibility of navigated TIPSS creation was tested in a phantom by two interventional radiologists (A/B) followed by in-vivo testing evaluation in eight domestic pigs. Procedure duration and number of attempts needed for puncture of the portal vein were recorded. RESULTS: In the phantom setting, intervention time to gain access to the portal vein (PV) was 144 ± 67 s (A) and 122 ± 51 s (B), respectively. In the in-vivo trials, TIPS could be successfully completed in five out of eight animals. Mean time for the complete TIPS was 245 ± 205 minutes with a notable learning curve towards the last animal. CONCLUSIONS: TIPS creation with the use of electromagnetic tracking technology proved to be feasible in-vitro as well as in-vivo. The system may be useful to facilitate challenging TIPSS procedures.

Revival of monophasic contrast injection protocols: superiority of a monophasic injection protocol compared to a biphasic injection protocol in high-pitch CT angiography.

BACKGROUND: Biphasic injection protocols are frequently used because they yield homogenous contrast enhancement. We hypothesize that with faster scanners and shorter scan times, biphasic injection protocols are no longer necessary. PURPOSE: To evaluate whether a monophasic injection protocol is equivalent to a biphasic protocol in terms of contrast enhancement and homogeneity. MATERIAL AND METHODS: Repeated high-pitch CTA (pitch 3) and conventional standard-pitch computed tomography angiography (CTA) (pitch 1.2) from the cervical region to the symphysis was performed in seven beagles (11.2 ± 2.5 kg) in a cross-over study design. Arterial contrast enhancement was measured along the z-axis in the ascending, descending, and abdominal aorta and the iliac arteries. The z-axis is the longitudinal axis of the human body and at the same time the direction in which the CT table is moving. The data were analyzed using repeated measures ANOVA with a post-hoc t-test and visual assessment of the scans. RESULTS: In high-pitch CTA, monophasic injection protocols were superior to biphasic injection protocols in enhancement levels (P < 0.05) and enhancement homogeneity along the z-axis (P < 0.05). In conventional CTA, enhancement levels did not differ. Contrast homogeneity was better for biphasic protocols. CONCLUSION: High-pitch CTA monophasic injection protocols are superior to biphasic injection protocols, due to a higher and more homogeneous contrast enhancement with the same amount of contrast medium used.

Age- and Sex-Specific Reference Values for Renal Volume and Association with Risk Factors for Chronic Kidney Disease in a General Population-An MRI-Based Study.

BACKGROUND: Renal volume (RV) is associated with renal function and with a variety of cardiovascular risk factors (CVRFs). We analysed RV using magnetic resonance imaging (MRI) in a large population-based study (Study of Health in Pomerania; SHIP-TREND) to find sex- and age-specific reference values for RV and to test the influence of several markers on RV. The main objective is to describe reference values for RV in people from the general population without kidney disease. METHODS: 1815 participants without kidney disease (930 women) aged 21-81 years were included in our study. Right and left RV with and without body surface area (BSA) indexation were compared among three age groups (22-39 years, 40-59 years, 60-81 years) by median and interquartile range and tested separately in women and men. RESULTS: The estimated glomerular filtration rate (eGFR), serum uric acid, and right and left RV were higher in men compared to women (all p < 0.001). Left kidneys were larger than right kidneys (both sexes). With age, RV showed a continuously decreasing trend in women and an upside-down U-shaped relation in men. In multivariable linear regression models, current smoking (ß = 14.96, 95% CI 12.12; 17.79), BSA (ß = 97.66, 95% CI 90.4; 104.93), diastolic blood pressure (ß = 0.17, 95% CI 0.01; 0.32), and eGFR (ß = 0.57, 95% CI 0.50; 0.65) were positively associated with both left and right RV, whereas uric acid (ß = -0.03, 95% CI -0.05; -0.01) showed an inverse association with RV. Interestingly, the same eGFR correlated with higher RV in men compared to women. CONCLUSION: Reference values for RV are different for age groups and sex. For any given age, female kidneys are smaller than male kidneys. RV associates positively with eGFR, but for any chosen eGFR, renal volume in females is lower compared to males. RV decreases with age, but in men showed a U-shaped correlation. This may reflect hyperfiltration and glomerular hypertrophy associated with the presence of CVRF in middle-aged males.

Impact of aortic valve calcification severity and impaired left ventricular function on 3-year results of patients undergoing transcatheter aortic valve replacement.

OBJECTIVES: To evaluate clinical pre-interventional predictors of 3-year outcome and mortality in high-risk patients with severe aortic valve stenosis treated with transcatheter aortic valve implantation (TAVI). METHODS: Among 367 patients included in the Aachen TAVI registry, 76 patients with baseline dual-source computed tomography (DSCT) for the quantification of aortic valve calcification (AVC) and a 3-year follow-up were identified. RESULTS: Survival at 30 days was 91 %, and it was 75 %, 66 % and 64 % at 1, 2 years and 3 years, respectively. Non-survivors at 3 years showed a significantly higher Agatston AVC score (2,854 ± 1,651) than survivors (1,854 ± 961, P = 0.007). Multivariate analysis including age, logistic EuroScore, glomerular filtration rate, Agatston AVC score, ejection fraction < 40 %, NYHA class, baseline medication, chronic lung disease and aortic regurgitation revealed that only the Agatston AVC score (P = 0.03) and impaired left ventricular function (P = 0.001) was significantly associated with mortality. Patients with Agatston AVC scores >2,000 had a significantly lower 3-year survival rate compared with patients with scores <2,000 (47 % vs 79 %, P = 0.004). CONCLUSIONS: In patients referred for TAVI, aortic valve calcification severity and impaired left ventricular function may serve as a predictor of long-term mortality. Therefore, AVC scores easily determined from pre-procedural CT datasets may be used for patient risk stratification.

Sclerostin as a potential novel biomarker for aortic valve calcification: an in-vivo and ex-vivo study.

BACKGROUND AND AIM OF THE STUDY: Sclerostin is a key negative regulator of bone formation. It was hypothesized that sclerostin might also play a potential role in the development of aortic valve calcification (AVC). The study aim was to evaluate serum sclerostin levels in patients with different degrees of AVC compared to a healthy control group, and to investigate local sclerostin expression in explanted calcified and non-calcified aortic valves. METHODS: A prospective cross-sectional study was performed in 115 patients (mean age 74 +/- 7 years) with echocardiographically proven AVC. Sclerostin serum levels were measured using ELISA and compared to values obtained from a healthy control population. For quantification of AVC, all patients of the study cohort underwent non-contrast-enhanced dual-source computed tomography (DSCT). Immunohistochemistry (IHC) staining for sclerostin and mRNA sclerostin expression was analyzed in 10 calcified aortic valves and 10 non-calcified age-matched control valves. RESULTS: Patients with AVC showed significantly higher sclerostin serum levels as compared to healthy controls (0.94 +/- 0.45 versus 0.58 +/- 0.26 ng/ml, p < 0.001). A significant correlation between sclerostin serum levels and Agatston AVC scores as assessed by DSCT was observed (r = 0.62, p < 0.001) in the study cohort. IHC revealed positive sclerostin staining in nine calcified valves, in contrast to negative staining for sclerostin in all non-calcified valves. Quantitative real-time PCR confirmed the increased sclerostin expression on mRNA level, with a significant up-regulation of sclerostin mRNA (fold change 150 +/- 52, p < 0.001) expression being shown in calcified aortic valves compared to non-calcified control valves. Co-staining experiments revealed that sclerostin-expressing cells co-express the major osteogenic transcription factor Runx2 and the extracellular matrix protein osteocalcin. CONCLUSION: Patients with AVC showed increased sclerostin serum levels compared to a healthy reference population, and it was revealed that the severity of AVC may be linked to increased sclerostin serum levels. Moreover, the PCR and staining data demonstrated an increased sclerostin expression in parallel to prototypic markers of osteogenic transdifferentiation, indicating a role of sclerostin in the valvular calcification process.

Animal experimental evaluation of a new sealing device for indwelling arterial catheters.

BACKGROUND: Hematoma is a common complication following arterial puncture. To date no device that allows sealing of an arterial puncture site with in-situ catheter has been developed. PURPOSE: To evaluate a newly developed arterial sealing device for endovascular catheters in an in-vivo experimental setting. MATERIAL AND METHODS: A peelable collagen-based vascular sealing device for endovascular catheters was tested in acute (follow-up: 4 h; n = 2) and chronic (follow-up: 1 week; n = 4) settings in the femoral artery (FA) of sheep. After implantation correct position of the device as well as patency of the FA were verified angiographically. In the chronic group, hematoma was excluded and patency of FA was assured using color Doppler ultrasound 1 and 3 days after the procedure. After 1 week a final ultrasound and an angiography were performed for final evaluation. Thereafter, the animals were sacrificed and the puncture site was dissected and analyzed macroscopically. RESULTS: Sufficient sealing of the puncture site could be observed in all animals. In acute and chronic experiments, neither a hematoma at the puncture site nor other complications were observed after positioning the sealing device. Follow-up color Doppler ultrasounds (CDUS) and final angiography revealed patent FAs in all animals. Macroscopic evaluation of dissection material proved collagen plug and catheter being in place. CONCLUSION: Our preliminary in-vivo results demonstrate a safe and convenient vascular sealing system for endovascular catheters. No acute or chronic complications were observed.

Radiofrequency and microwave ablation controls hepatic oligoprogression of advanced gastroenteropancreatic neuroendocrine tumors.

In progression of multifocal liver metastases of gastroenteropancreatic neuroendocrine tumors (GEP-NET) escalation of systemic therapy is indicated. The aim of this retrospective study was to investigate the potential of local thermal ablation in hepatic oligoprogression and otherwise stable disease in GEP-NET. Patients with hepatic oligoprogression and otherwise stable disease, who underwent radiofrequency ablation (RFA) or microwave ablation (MWA) for local control, were included in the study. Thermal ablation was performed while maintaining the ongoing systemic therapy or without addition of a systemic therapy. The effectiveness of this therapeutic approach was evaluated by determination of local treatment success, improvement of progression-free survival (PFS) and the safety. Seventeen thermal ablation procedures were performed in 13 patients with well differentiated NET including seven ileum NET, four pancreatic NET, one appendix NET and one rectum NET. RFA and MWA of liver metastases were well tolerated without major complications. Thermal ablation resulted in an estimated median PFS of 62.6 weeks (mean 50.5 weeks; range 10.1-78.9 weeks) per procedure. In four patients, two ablation procedures were performed throughout the course of their disease resulting in an estimated median PFS of 69.1 weeks (mean 71.6 weeks; range 10.1-123.1 weeks) per patient. Start or change of systemic therapy could be delayed up to 123.1 weeks by using thermal ablations for isolated progression of single liver metastases. 88% of thermal ablations prolonged PFS. Thermal ablation of liver metastases in a non-curative intent has the potential to provide focal growth control and to prolong PFS in GEP-NET patients with hepatic oligoprogression.

Electrocardiographic and imaging predictors for permanent pacemaker requirement after transcatheter aortic valve implantation.

BACKGROUND AND AIM OF THE STUDY: Pacemaker (PM) implantation is a possible requirement after transcatheter aortic valve implantation (TAVI). The study aim was to evaluate the electrocardiographic and imaging predictors of the need for PM implantation after TAVI. METHODS: A total of 80 consecutive patients (mean age 82 +/- 6 years) who had been referred for TAVI were included in the study. Transfemoral TAVI was performed in 58 patients (CoreValve ReValving; 72%), while 22 patients (28%) underwent transapical TAVI using the Edwards SAPIEN valve. Patient characteristics, and the frequency of atrioventricular (AV) block, right bundle branch block (RBBB) and left bundle branch block (LBBB), were evaluated for the prediction of PM implantation after TAVI. In addition, the severity and distribution of aortic valve calcification (AVC) were assessed by calculating the Agatston AVC score for the total aortic valve, as well as for each cusp, using dual-source computed tomography. RESULTS: Pre-procedural RBBB was present in six patients (8%), while eight patients (10%) showed pre-procedural LBBB. In 20 of the 80 patients (25%), a new LBBB was observed after TAVI. In 17 TAVI patients (21%; only CoreValve patients) there was an indication for permanent PM implantation that was related to complete AV block (n = 13) or complete RBBB or LBBB with AV delay (n = 4). Four of six patients (67%) with pre-procedural RBBB received a PM after TAVI. Multivariate logistic regression analysis revealed that only prosthesis type (r = 0.30, p = 0.01) and pre-procedural RBBB (r = 0.4, p = 0.02) were significantly associated with the need for permanent PM implantation after TAVI. CONCLUSION: TAVI is frequently associated with new conduction disturbances. A higher incidence of new LBBB and of permanent PM requirement occurred with the CoreValve ReValving system. There was no relationship between the severity or distribution of AVC and the need for PM implantation after TAVI. Patients with pre-procedural RBBB are deemed to be at risk for PM implantation after TAVI.

Comparison of dual-source CT angiography and MR angiography in preoperative evaluation of intra- and extracranial vessels: a pilot study.

Besides the assessment of carotid artery stenosis, evaluation of the vascular anatomy and lesions within both the extra- and intracranial arteries is crucial for proper clinical evaluation, treatment choice and planning. The purpose of our study was to evaluate the potential of dual-source CTA and 3T-MRA. In 16 symptomatic CAS patients, contrast-enhanced DSCT and 3T-MRA examinations were performed. For DSCT a dual-energy protocol with a 64 x 0.6-mm collimation was applied. In 3T-MRA intracranial high-resolution unenhanced TOF and extracranial contrast-enhanced MRA were performed. All examinations were analyzed for relevant morphologic and pathologic features or anomalies, and a total of 624 vessel segments were scored. All examinations were of diagnostic image quality with good to excellent vessel visibility. Almost all intracranial arteries were significantly better visualized by MRA compared to CTA (five of six vessels, p < 0.05). DSCT however allowed for further morphological carotid stenosis description, especially with respect to calcification. Although MRA proved to be superior in visualization of smaller intracranial arteries, all pre-interventionally relevant information could be perceived from DSCT. DSCT and MRA may both be regarded as a reliable, fast, pre-interventional imaging investigation in patients with carotid artery stenosis.

Carbon dioxide-enhanced CT-guided placement of aortic stent-grafts: feasibility in an animal model.

PURPOSE: To test the feasibility of carbon dioxide (CO(2))-enhanced computed tomography (CT)-guided placement of infrarenal abdominal aortic stent-grafts in an animal model. METHODS: Appearance of a stent-graft mounted on its deployment system and the feasibility of CT fluoroscopy-guided placement were analyzed in an in vitro setting. Five domestic pigs weighing 70 to 80 kg underwent CO(2)-enhanced 64-slice CT arteriography (CTA). After surgical exposure of the right iliac artery, an 18-mm stent-graft was advanced into the abdominal aorta. Infrarenal position of the graft was monitored using CT fluoroscopy with CO(2) administered intermittently in a flow-regulated manner using a computer-controlled injection system. After the final position of the stent-graft was determined, the graft was deployed under CT fluoroscopy guidance. Graft position was confirmed by contrast enhanced 64-slice CTA and conventional catheter angiography. To quantitatively assess the position of the stent-graft, the distance between the proximal stent struts and the radiopaque marker was determined using an electronic caliper. RESULTS: CT-guided placement of infrarenal aortic stent-grafts was feasible in all animals without complications. CO(2)-enhanced CTA allowed for the identification of the renal arteries in all animals. CT fluoroscopy permitted the continuous online monitoring of stent deployment. In all animals, the grafts were placed without impairment of renal artery flow or stent-graft dislocation. The mean distance between the stent-graft and origin of the more caudal renal artery was 0.9+/-0.3 mm. CONCLUSION: CO(2)-enhanced CT fluoroscopy permits the precise placement of infrarenal aortic stent-grafts in an animal model.

Association of fetuin-A levels with the progression of aortic valve calcification in non-dialyzed patients.

AIMS: Fetuin-A has been identified as a potent circulating inhibitor of ectopic calcification. We investigated the relationship between baseline fetuin-A serum levels and the rate of progression of aortic valve calcification (AVC) in non-dialyzed patients with aortic valve disease (AVD). METHODS AND RESULTS: Seventy-seven patients (mean age 70 +/- 8 years) with echocardiographically proven AVD were collected. In all patients, serum fetuin-A levels, creatinine, calcium, lipid parameters, and C-reactive protein were measured at baseline. For quantification of AVC progression, all patients underwent multislice spiral computed tomography examinations at baseline and after a mean follow-up of 12.6 +/- 1.4 months (range 7-18 months). In a multifactorial analysis of covariance including fetuin-A levels, baseline AVC score, the covariables sex, age, body mass index, C-reactive protein, glomerular filtration rate, serum lipids, diabetes, smoking status, and hypertension, only serum fetuin-A levels significantly predict the progression of AVC (P < 0.001). Post hoc analysis demonstrated that patients with baseline fetuin-A levels lower than the median of the cohort (0.72 g/L) showed a significantly higher increase of AVC scores (34.6 +/- 31.4%) than patients with fetuin-A levels larger than the median (10.0 +/- 11.2%, P < 0.001) despite comparable baseline AVC scores. In addition, fetuin-A levels were associated with major adverse clinical events (MACE; P = 0.03). CONCLUSION: Serum levels of the calcification inhibitor fetuin-A are associated with the progression of AVC and MACE, independent of the renal function and inflammation.

Relation of circulating Matrix Gla-Protein and anticoagulation status in patients with aortic valve calcification.

Matrix-Gla Protein (MGP) is a vitamin K-dependent protein acting as a local inhibitor of vascular calcification. Vitamin K-antagonists (oral anticoagulant; OAC) inhibit the activation of MGP by blocking vitamin K-metabolism. The aim of this study was to investigate the effect of long-term OAC treatment on circulating MGP levels in humans and on MGP expression in mice. Additionally, we tested the association between circulating inactive MGP (ucMGP) levels and the presence and severity of AVC in patients with aortic valve disease (AVD). We analysed circulating ucMGP levels in 191 consecutive patients with echocardiographically proven calcific AVD and 35 control subjects. The extent of AVC in the patients was assessed by multislice spiral computed tomography. Circulating ucMGP levels were significantly lower in patients with AVD (348.6 +/- 123.1 nM) compared to the control group (571.6 +/- 153.9 nM, p < 0.001). Testing the effect of coumarin in mice revealed that also the mRNA expression of MGP in the aorta was downregulated. Multifactorial analysis revealed a significant effect of glomerular filtration rate and long-term OAC therapy on circulating ucMGP levels in the patient group. Subsequently, patients on long-term OAC had significantly increased AVC scores. In conclusion, patients with calcific AVD had significantly lower levels of circulating ucMGP as compared to a reference population, free of coronary and valvular calcifications. In addition, our data suggest that OAC treatment may decrease local expression of MGP, resulting in decreased circulating MGP levels and subsequently increased aortic valve calcifications as an adverse side effect.

Quantification of aortic valve calcification using multislice spiral computed tomography: comparison with atomic absorption spectroscopy.

OBJECTIVES: Multislice spiral computed tomography (MSCT) allows the in vivo detection of valvular calcification. The aim of this study was to validate the quantification of aortic valve calcification (AVC) by MSCT with in vitro measurements by atomic absorption spectroscopy. METHODS: In 18 patients with severe aortic stenosis, 16 detector row MSCT (SOMATOM Sensation 16, Siemens, Forchheim, Germany with scan parameters as follows: 420 milliseconds tube rotation time, 12 x 0.75 mm collimation, tube voltage 120 KV) was performed before aortic valve replacement. Images were reconstructed at 60% of the RR interval with an effective slice thickness of 3 mm and a reconstruction increment of 2 mm. AVC was assessed using Agatston AVC score, mass AVC score, and volumetric AVC score. After valve replacement, the calcium content of the excised human stenotic aortic valves was determined in vitro using atomic absorption spectroscopy. RESULTS: The mean Agatston AVC score was 3,842 +/- 1,790, the mean volumetric AVC score was 3,061 +/- 1,406, and mass AVC score was 888 +/- 492 as quantified by MSCT. Atomic absorption spectroscopy showed a mean true calcification mass (Ca5(PO4)3OH) of 19 +/- 8 mass%. There was a significant correlation between in vivo AVC scores determined by MSCT and in vitro mean true calcification mass (r = 0.74, P = 0.0004 for mass AVC score, r = 0.79, P = 0.0001 for volumetric AVC score and r = 0.80, P = 0.0001 for Agatston AVC score) determined by atomic absorption spectroscopy. Linear regression analysis showed a significant association between the degree of hydroxyapatite (given in mass%) in the aortic valve and the degree of AVC (R = 0.74, F = 19.6, P = 0.0004 for mass AVC score, R = 0.80, F = 29.3, P = 0.0001 for Agatston AVC score and R = 0.79, F = 27.3, P = 0.0001 for volumetric AVC score) assessed by MSCT. CONCLUSION: MSCT allows accurate in vivo quantification of aortic valve calcifications.

Relation of oral anticoagulation to cardiac valvular and coronary calcium assessed by multislice spiral computed tomography.

Vitamin K antagonists, known as oral anticoagulants, affect the synthesis and function of the matrix Gla protein, which is a potent inhibitor of tissue calcification. We performed multislice spiral computed tomography in 86 patients (53 men, mean age 71 +/- 8 years) with calcific aortic valve disease to quantitate the amount of calcification in the aortic valve and coronary arteries. Patients with long-term oral anticoagulation therapy (mean duration 88 +/- 113 months; n = 23) were compared with those without anticoagulation (n = 63). No differences were found in the demographic, clinical, or echocardiographic characteristics between the 2 study groups. Patients on oral anticoagulant therapy had increased coronary calcium (coronary Agatston score 1,561 +/- 1,141 vs 738 +/- 978, respectively; p = 0.024) and valvular calcium (valvular Agatston score 2,410 +/- 1,759 vs 1,070 +/- 1,085, respectively; p = 0.002) compared with patients without anticoagulation treatment. The results of our study have demonstrated that oral anticoagulation may be associated with increased valvular and coronary calcium in patients with aortic valve disease, presumably due to decreased activation of the matrix Gla protein.

Preliminary experience in the assessment of aortic valve calcification by ECG-gated multislice spiral computed tomography.

BACKGROUND: The aim was to correlate the degree of valvular calcification in patients with aortic stenosis determined by retrospectively electrocardiogram (ECG)-gated multislice spiral computed tomography with stenosis severity assessed by cardiac catheterization. METHODS: Prospective study on 41 patients (18 men, mean age 71+/-8 years) with aortic stenosis, who underwent four detector row multislice spiral computed tomography and cardiac catheterization. Severity of aortic stenosis was classified by cardiac catheterization. Aortic valve area, peak to peak and mean transvalvular gradients were correlated with the degree of calcification determined by multislice spiral computed tomography. Aortic valve calcification was assessed using aortic Agatston score, aortic mass score and aortic volume score. RESULTS: All measured aortic valve calcification scores were significantly higher in patients with severe aortic stenosis (n=29) than in patients with moderate (n=7) or mild aortic stenosis (n=5, p<0.001). Aortic valve calcification scores correlated significantly with aortic valve area (r=-0.49, p=0.001 for aortic mass score) and with peak to peak (r=0.68, p<0.001) and mean (r=0.60, p<0.001) transvalvular gradients. CONCLUSIONS: Severity of aortic valve calcification assessed by cardiac multislice spiral computed tomography is inversely related to aortic valve area and positively correlated with transvalvular gradients. Based on this preliminary data larger studies should be performed with echocardiography as a reference standard in order to validate this new information and its utility in the clinical management of the patient.

Optimizing contrast media injection protocols in state-of-the art computed tomographic angiography.

OBJECTIVE: Very short acquisition times and the increasing use of low-kilovolt protocols in standard computed tomographic (CT) angiography (CTA) examinations demand modifications in the contrast media (CM) injection regimen. The aim of this study was to optimize the use of tube voltage-adjusted CM delivery parameters, especially injection duration and iodine delivery rate (IDR), in thoracoabdominal CTA in a porcine model. MATERIALS AND METHODS: Eight pigs (53-72 kg) were examined with a third-generation dual-source CT system with a dynamic CTA protocol (4-dimensional spiral, 454-mm scan length, 2.5-second temporal resolution, 70-second total acquisition time). Six CM injection protocols were applied in randomized order and intraindividually compared. The standard CTA protocol was performed at 120 kV, with an injection of 300 mg iodine/kg body weight and a flow of 5 mL/s (IDR, 1.5 g/s). On the basis of phantom measurements for the low-kilovolt CTA protocols, the iodine dosage was adjusted to 150 mg iodine/kg (70 kV) and 210 mg iodine/kg (90 kV). Therefore, either the IDR was kept constant and the injection time was reduced, or the injection time was kept constant and the IDR was reduced by modifying the CM flow or concentration. Time attenuation curves, time to peak, and peak enhancement were calculated for different locations within the aorta, renal arteries, and large veins. RESULTS: The heart rates were comparable among the different injection protocols (66.9-78.1 beats per minute). The average injection peak pressure depended on the flow rate and CM concentration and ranged from 42.9 to 114.7 psi. The average arterial peak enhancement was comparable for protocols with identical injection times and reduced IDR (362.4 HU [standard 120-kV protocol; 300 mg iodine/kg; IDR, 1.5 g/s], 360.0 HU [70 kV; 150 mg iodine/kg; IDR, 0.75 g/s], 365.4 HU [70 kV; 150 mg iodine/kg; IDR, 0.75 g/s; CM, 150 mg iodine/mL], 344.3 HU [90 kV; 210 mg iodine/kg; IDR, 1.1 g/s]). Higher peak enhancements could be achieved by applying protocols with identical IDR and a reduced injection time (502.5 HU [70 kV; 150 mg iodine/kg; IDR, 1.5 g/s] and 394.6 HU [90 kV; 210 mg iodine/kg; IDR, 1.5 g/s]). CONCLUSIONS: By adjusting the IDR, low-kilovolt CTA is able to achieve comparable aortic enhancement with a significant reduction in CM dosage. A shorter injection time at constant IDR results in higher enhancement and a narrower scan window and might be preferable for fast CTA acquisition techniques. CLINICAL RELEVANCE/APPLICATION: The optimization of CM injection protocols is mandatory to achieve state-of the art CTA at low kilovolt and can reduce CM doses to patients.

[Scientia - Humanitati - Patriae. Formation of the Society for Military Medicine in the Federal Republic of Germany]. / Scientia - humanitati - patriae. Neubeginn der Wehrmedizinischen Gesellschaft in der Bundesrepublik Deutschland.

Since 1864 military medical associations have a long tradition in Germany that ended with World War II. The formation of the first society for military medicine after World War II and its early development from 1954 to 1968 is described. Considering aims, purpose, organizational structure and the results of the associations work, the early years of the societies existence have to be divided in three different phases; 1. association of former officers of the military medical service (1954-1957); 2. conceptual reorganization (1957-1961); 3. creation of a modern society for military medicine (1961-1968). During these phases the society developed from a small community of interest to a full medical association. In its early years the society exclusively dealt with the provision of former officers of the Wehrmacht's medical service. Over the years the society managed to extend its spectrum towards international cooperation, education and scientific support in the entire field of military medicine.

Evaluation of aortic root for definition of prosthesis size by magnetic resonance imaging and cardiac computed tomography: implications for transcatheter aortic valve implantation.

BACKGROUND: This study sought to compare cardiac magnetic resonance imaging (CMR) with dual source computed tomography (DSCT) for analysis of aortic root dimensions prior to transcatheter aortic valve implantation (TAVI). In addition, the potential impact of CMR and DSCT measurements on TAVI strategy defined by 2D-transesophageal echocardiography (TEE) was evaluated. METHODS: Aortic root dimensions were measured using CMR and DSCT in 58 patients referred for evaluation of TAVI. The TAVI strategy (choice of prosthesis size and decision to implant) was based on 2D-TEE annulus measurements. RESULTS: CMR and DSCT aortic root measurements showed an overall good correlation (r=0.86, p<0.001 for coronal aortic annulus diameters). There was also a good correlation between TEE and CMR as well as between TEE and DSCT for measurement of sagittal aortic annulus diameters (r=0.69, p<0.001). However, annulus diameters assessed by TEE (22.1±2.3mm) were significantly smaller than coronal aortic annulus diameters assessed by CMR (23.4±1.8mm, p<0.001) or DSCT (23.6±1.8, p<0.001). Regarding TAVI strategy, the agreement between TEE and sagittal CMR (kappa=0.89) as well as sagittal DSCT measurements (kappa=0.87) was statistically perfect. However, decision based on coronal CMR- or MSCT measurements would have modified TAVI strategy as compared to a TEE based choice in a significant number of patients (22% to 24%). CONCLUSION: In patients referred for TAVI, CMR measurements of aortic root dimensions show a good correlation with DSCT measurements and thus CMR may be an alternative 3D-imaging modality. Aortic annulus measurements using TEE, CMR and DSCT were close but not identical and the method used has important potential implications on TAVI strategy.

Association of aortic valve calcification severity with the degree of aortic regurgitation after transcatheter aortic valve implantation.

BACKGROUND: This study sought to examine a possible relationship between the severity of aortic valve calcification (AVC), the distribution of AVC and the degree of aortic valve regurgitation (AR) after transcatheter aortic valve implantation (TAVI) for severe aortic stenosis (AS). METHODS: 57 patients (22 men, 81 ± 5 years) with symptomatic AS and with a logistic EuroSCORE of 24 ± 12 were included. 38 patients (67%) received a third (18F)-generation CoreValve® aortic valve prosthesis, in 19 patients (33%) an Edwards SAPIEN™ prosthesis was implanted. Prior to TAVI dual-source computed tomography for assessment of AVC was performed. To determine the distribution of AVC the percentage of the calcium load of the most severely calcified cusp was calculated. After TAVI the degree of AR was determined by angiography and echocardiography. The severity of AR after TAVI was related to the severity and distribution of AVC. RESULTS: There was no association between the distribution of AVC and the degree of paravalvular AR after TAVI as assessed by angiography (r = -0.02, p = 0.88). Agatston AVC scores were significantly higher in patients with AR grade ≥ 3 (5055 ± 1753, n = 3) than in patients with AR grade < 3 (1723 ± 967, p = 0.03, n = 54). Agatston AVC scores > 3000 were associated with a relevant paravalvular AR and showed a trend for increased need for second manoeuvres. There was a significant correlation between the severity of AVC and the degree of AR after AVR (r = 0.50, p < 0.001). CONCLUSION: Patients with severe AVC have an increased risk for a relevant AR after TAVI as well as a trend for increased need for additional procedures.

Multislice computed tomography for comprehensive assessment of the heart in acute chest pain: a case report.

INTRODUCTION: Over the last decade cardiac computed tomography emerged as a non-invasive imaging modality for the assessment of the heart and the coronary arteries. Only recently its use for patient management in the emergency department was suggested. CASE PRESENTATION: We present an 84-year old male patient with concomitant early in-stent restenosis after coronary artery stent placement, myocardial infarction, left and right ventricular thrombi and aortic valve stenosis. Diagnoses were made on emergency cardiac computed tomography. All findings were confirmed by catheter coronary angiography, echocardiography and cardiac magnetic resonce imaging. CONCLUSION: The comprehensive emergency work-up by cardiac computed tomography, illustrates the potential value of cardiac computed tomography in the emergency setting.