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Gabriele A Krombach

Publications and source records attributed to Gabriele A Krombach.

27 records · Page 2Linked to original sources
PubMed2003

Validation of an evaluation routine for left ventricular volumes, ejection fraction and wall motion from gated cardiac FDG PET: a comparison with cardiac magnetic resonance imaging.

The aim of this study was to validate the estimation of left ventricular end-diastolic and end-systolic volumes (EDV, ESV) and ejection fraction (LVEF) as well as wall motion analysis from gated fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) in patients with severe coronary artery disease (CAD) using software originally designed for gated single-photon emission tomography (SPET). Thirty patients with severe CAD referred for myocardial viability diagnostics were investigated using a standard FDG PET protocol enhanced with gated acquisition (8 gates per cardiac cycle). EDV, ESV and LVEF were calculated using standard software designed for gated SPET (QGS). Wall motion was analysed using a visual four-point wall motion score on a 17-segment model. As a reference, all patients were also examined within a median of 3 days with cardiovascular cine magnetic resonance imaging (cMRI) (20 gates per cardiac cycle). Furthermore, all gated FDG PET data sets were reoriented in a second run with deliberately misaligned axes to test the quantification procedure for robustness. Correlation between the results of gated FDG PET and cMRI was very high for EDV and ESV ( R=0.96 and R=0.97) and for LVEF ( R=0.95). With gated FDG PET, there was a non-significant tendency to underestimate EDV (174+/-61 ml vs 179+/-59 ml, P=0.21) and to overestimate ESV (124+/-58 ml vs 122+/-60 ml, P=0.65), resulting in underestimated LVEF values (31.5%+/-9.4% vs 34.2%+/-12.4%, P<0.003). The results of reorientations 1 and 2 showed very high correlations (for all R>/=0.99). Segmental wall motion analysis revealed good agreement between gated FDG PET data and cMRI (kappa =0.62+/-0.03). In conclusion, despite small systematic differences which contributed mainly to the lower temporal resolution of gated FDG PET, agreement between gated FDG PET and cMRI was good across a wide range of volumes and LVEF values as well as for wall motion analysis. Therefore, gated FDG PET provides clinically relevant information on function and volumes, using the commercially available software package QGS.

Aged↗
PubMed2003

Fast interactive real-time magnetic resonance imaging of cardiac masses using spiral gradient echo and radial steady-state free precession sequences.

RATIONALE AND OBJECTIVES: Cardiac and respiratory controlled MR-imaging is the gold standard for imaging of cardiac masses. However, this technique may be limited in patients with dyspnoe or arrhythmia. The aim of this study was the evaluation of an interactive MR-approach for the detection and localization of cardiac masses. METHODS: Interactive real-time spiral gradient-echo (spiralGE) and radial steady-state-free-precession (radialSSFP) MR-imaging was performed during free-breathing and without cardiac triggering in 15 patients with 14 intracardiac or paracardiac masses. Standard cardiac triggered segmented k-space breath-hold steady-state-free-precession cine MR-imaging was used as the reference MR-imaging technique. Two groups of investigators blinded to clinical data were ask to rank image quality and to identify cardiac masses on real-time MR-images. RESULTS: Image quality was superior using radialSSFP when compared with spiralGE. Using radialSSFP all masses were correctly detected while 6 of 14 masses were missed on spiralGE. Mean real-time MR-imaging time was less than 3 minutes for both techniques. CONCLUSION: Interactive real-time radialSSFP MR-imaging allows for accurate and fast detection of cardiac masses without the need of cardiac or respiratory triggering.

Female↗
PubMed2003

Endovascular stents in pulmonary valve and artery in swine: feasibility study of MR imaging-guided deployment and postinterventional assessment.

PURPOSE: To assess the feasibility of using magnetic resonance (MR) imaging to guide stent deployment in the pulmonary valve and artery and evaluate, after stent deployment, the position and morphology of and blood flow through the stent. MATERIALS AND METHODS: Angiography and 1.5-T MR imaging were performed in a dual-imaging suite. Nitinol stents were placed in the pulmonary valve and main pulmonary artery in five pigs by using MR imaging guidance. For interactive MR imaging monitoring of catheter manipulation and stent delivery, balanced fast field-echo and T1-weighted turbo field-echo sequences were used. Visualization of the delivery system was based on T2* (with air as the contrast material) or T1 (with gadodiamide as the contrast material). After stent deployment, the position and morphology of and flow through the stent were verified with multiphase multisection balanced fast field-echo and velocity-encoded cine MR imaging. Findings at angiography and postmortem examination also helped verify stent placement. The paired Student t test was used for data analysis. RESULTS: The stent was successfully deployed in all animals. The stent was placed distal to the pulmonary valve in four animals and across the pulmonary valve in one animal. The position and morphology of the stent were clearly depicted on balanced fast field-echo images. In the animal with the stent placed across the pulmonary valve, the pulmonary regurgitant fraction was 37%; this was not seen in the animals with stents placed distal to the pulmonary valve. No complication (eg, stent migration, intramural injury, or vascular perforation) was noted during the intervention. Findings at angiography and postmortem examination confirmed the position of the stents. CONCLUSION: MR imaging has the potential to guide stent placement in the pulmonary valve or artery and to evaluate flow volume within the stent lumen after the intervention.

Alloys↗
PubMed2002

Blood pool contrast-enhanced MRI detects suppression of microvascular permeability in early postinfarction reperfusion after nicorandil therapy.

Nicorandil is an adenosine triphosphate-sensitive potassium channel opener with a nitrate-like effect. It is approved for clinical use in Europe and Japan as an antianginal drug. The purpose of this investigation was to assess the acute effects of nicorandil therapy on microvascular injury using the blood pool MR contrast medium, NC100150 injection (Clariscan). Microvascular injury was produced in 24 rats using 45 min of coronary occlusion / 3 hr reperfusion. Nicorandil was infused at 15 min of occlusion and during reperfusion. Control animals received a saline solution. MR imaging was used to characterize microvascular permeability, quantify the extent of microvascular injury, LV volume, and wall thickness. Hyperenhancement at 30 min after administration of 0.05 mmol/kg Clariscan mapped the extent of ischemia-induced loss of microvascular integrity. The accumulation of Clariscan in the injured region was significantly suppressed in nicorandil compared to control rats. Nicorandil reduced the extent of microvascular injury from 44 +/- 2% to 18 +/- 2% (P < 0.01) and true infarction size from 29 +/- 2% to 12 +/- 1%. The extent of the hyperenhanced region correlated with the true size of area at risk at autopsy. On spin-echo MRI during end-diastole, nicorandil reduced LV end-diastolic volume and preserved wall thickness in remote myocardium; both parameters are markers of LV dilatation caused by acute infarction (remodeling). In conclusion, blood pool contrast-enhanced MRI has the potential to depict and quantify the extent of microvascular permeability and injury. Nicorandil suppressed microvascular permeability, reduced infarction size, and improved LV function in early postinfarction reperfusion.

Animals↗
PubMed2002

Variation of the coronary calcium score depending on image reconstruction interval and scoring algorithm.

RATIONALE AND OBJECTIVES: To evaluate the reconstruction interval dependent bandwidth of the coronary calcium score, considering different methods of image reconstruction and quantification of coronary calcifications. MATERIALS AND METHODS: Seventy-five patients underwent coronary calcium scoring by use of retrospectively ECG-gated multislice spiral CT. In all patients overlapping and nonoverlapping image reconstruction was performed every 10% of the RR-interval. Coronary calcium score was calculated for every reconstructed image series using the Agatston score and a volumetric scoring method. In 25 patients the analysis was performed twice to determine the reconstruction interval dependent intraobserver variability. RESULTS: For nonoverlapping image reconstruction the median of the calcium score determined by the Agatston method ranged from 125.8 to 216.2 and from 166.9 to 211.7 for the volumetric scoring method. For overlapping image reconstruction the corresponding values ranged from 91.6 to 160.5 for the Agatston score and 128.3 to 175.3 for the volumetric calcium score. Reconstruction interval dependent median (mean) variation of the coronary calcium score ranged from 24.1 (45.5)% for nonoverlapping image reconstruction using the Agatston score to 17.5 (25.2)% utilizing a volumetric calcium score with overlapping image reconstruction. There was no statistical significant (P< 0.05) difference between the different methods. Intraobserver variability for the different image reconstruction intervals ranged from 0.78% to 21.51%. The least intraobserver variability was found for overlapping image reconstruction during the diastole using the volumetric scoring method. CONCLUSIONS: Diastolic image reconstruction at 50% or 60% of the RR-interval is recommendable for retrospectively ECG-gated multislice spiral CT. Volumetric calcium scoring and overlapping image reconstruction are beneficial to reduce the variation of the coronary calcium score.

Adult↗
PubMed2002

Left ventricular remodeling after infarction: sequential MR imaging with oral nicorandil therapy in rat model.

PURPOSE: To use magnetic resonance (MR) imaging in quantification of the short- and long-term effects of therapy with orally administered nicorandil on left ventricular (LV) geometry and function independent of infarction size. MATERIALS AND METHODS: Forty-six rats were subjected to reperfused infarction and randomly divided into two groups. Group 1 rats (n = 21) were treated with nicorandil (3 mg/kg/day in drinking water) for 4 days before infarction and 8 weeks after infarction (hereafter, the nicorandil group). Group 2 rats (n = 25) received tap water for the same period and served as the control group. Mesoporphyrin- (as a necrosis-specific agent) enhanced MR imaging was used to define necrotic myocardium on day 2 after infarction in all 46 animals. Contrast material-enhanced MR images showed large but identical infarction size in 11 control and 11 nicorandil rats. Only these 22 rats underwent repeat MR imaging at 8 weeks after infarction. The following variables were measured: LV volumes, ejection fraction, mass, wall thickness, and infarction size. Student t test and analysis of variance for repeated measurements were used for statistical analysis. RESULTS: The size of the necrotic region on mesoporphyrin-enhanced MR images was 39% +/- 3 of the size of the left ventricle in the control group and 41% +/- 2 in the nicorandil group (difference not significant, unpaired Student t test). Pretreatment with nicorandil for 6 days before imaging did not reduce LV dilation or improve function compared with those in control animals with identical infarction size. Eight weeks after infarction, control animals showed deterioration in LV function, wall thinning, and gradient in regional dysfunction (analysis of variance test). Nicorandil produced significant salutary effects on LV ejection fraction (37% +/- 3 in the nicorandil group vs 24% +/- 3 in the control group), end-diastolic volume (0.53 mL +/- 0.03 vs 0.65 mL +/- 0.04), end-systolic volume (0.36 mL +/- 0.03 vs 0.49 mL +/- 0.05), LV wall thickening in remote noninfarcted myocardium (28% +/- 2 vs 19% +/- 1), and a rim of infarction (16% +/- 2 vs 8% +/- 1) (P <.05 for all parameters). The increase in LV mass was reduced in the nicorandil group (0.73 g +/- 0.03) compared with that in the control group (0.89 g +/- 0.04) (P <.05). CONCLUSION: In animals studied longitudinally, MR imaging demonstrated the deleterious changes in LV geometry and function in the period after infarction and the salutary effects of medical therapy.

Administration, Oral↗
PubMed2002

MR imaging of spatial extent of microvascular injury in reperfused ischemically injured rat myocardium: value of blood pool ultrasmall superparamagnetic particles of iron oxide.

PURPOSE: To (a) assess the value of a blood pool magnetic resonance (MR) imaging contrast agent (Clariscan) for characterizing microvascular injury in ischemically injured rat myocardium and (b) compare the extent of microvascular injury at Clariscan-enhanced MR imaging with infarction and areas at risk seen with histochemical staining. MATERIALS AND METHODS: Twenty rats underwent 45 minutes of coronary artery occlusion and 3 hours of reperfusion. Sequential T1-weighted spin-echo MR images were acquired in 10 rats to assess leakage of Clariscan into myocardium over time. Ten other rats underwent the same duration of occlusion and reperfusion (3 hours) so that the extent of microvascular injury in the entire heart could be measured and correlated with infarction and area at risk at necropsy. The Student t test and Bland-Altman method were used for data analysis. RESULTS: Clariscan improved visualization of regions with transmural and nontransmural microvascular injury. Accumulation of Clariscan was best reflected by the mean ratios of signal intensity in injured myocardium to that in normal myocardium measured before (0.98 +/- 0.01 [standard error of the mean]) and after (1.34 +/- 0.04) injection. At 15 minutes after injection, the size of the enhanced region remained constant over the course of observation. The mean size of the hyperenhanced region (44% of the left ventricle +/- 2) was significantly (P <.001) larger than the mean size of true infarction at necropsy (29% +/- 3) but smaller than the mean size of the area at risk (50% +/- 2). CONCLUSION: Clariscan has potential for estimating the spatial extent of microvascular injury in ischemically injured myocardium and may be useful as a marker of microvascular injury after thrombolytic therapy.

Animals↗
PubMedDate not supplied

Color duplex sonography in post-therapeutic neck evaluation.

PURPOSE: Assessment of the clinical utility of color duplex sonography for post-therapeutic evaluation of the neck. PATIENTS AND METHODS: Eighty neck sides were evaluated in a prospective nonrandomized study during the post-therapeutic course. Of these, 74 previously had undergone surgery, and 60 subsequently had additional radiotherapy. The diagnostic procedures applied were clinical examination, computed tomography, positron emission tomography, and color duplex sonography. The mean observation period was 18.6 months. RESULTS: Seven of 80 (8.75%) neck sides exhibited recurrent disease, and 76.2% of the lymph nodes resected during the postoperative observation period showed malignancy. Color duplex echography could detect all lymph nodes. Sensitivity was 100%, and the specificity was 95.8%. The sensitivity and specificity of computed tomography and positron emission tomography were found to be 85.7% and 97.2%, respectively. Palpation had a sufficient specificity (95.8%) but only a very poor 14.2% sensitivity in the post-therapeutic neck. CONCLUSION: In complex tissue alterations of the post-therapeutic neck, color duplex echography is a highly sensitive and easily applied diagnostic procedure for the detection of recurrent disease. It allows a high-resolution depiction of intranodal vascularization and adjacent structures. Problems may occur in the evaluation of vessels in nodes with a diameter of 6 millimeters and below. This may impair specificity in some cases.

Head and Neck Neoplasms↗