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J Sandstede

Publications and source records attributed to J Sandstede.

At least 37 records · Page 2Linked to original sources
PubMed2000

[Evaluating signal intensity of movement-impaired myocardial segments in MR delayed images after administration of Gd-DTPA. Correlation of regional increase in contraction after revascularization].

PURPOSE: The aim of the study was to correlate delayed contrast enhancement of dysfunctional regions of the myocardium after injection of Gd-DTPA with the improvement of regional contractility 3 months after revascularization. MATERIAL AND METHODS: Eleven patients with coronary artery disease and wall motion abnormalities underwent MR imaging before and 3 months after revascularization therapy (PTCA or CABG). Short-axis images were acquired using a cine gradient echo sequence. After revascularization, a representative slice was analyzed 14 +/- 1 min after injection of 0.1 mmol/kg Gd-DTPA using a T1-weighted turbo fast low-angle shot sequence. Improved systolic wall thickening 3 months after revascularization served as criterion of viability and was correlated with delayed contrast enhancement patterns. RESULTS: After revascularization, 6 patients showed complete recovery of the dysfunctional area, 1 patient partial recovery, and 4 patients remained unchanged. All 4 patients with persisting wall motion abnormalities, 1/6 patients with recovery and the patient with partial recovery revealed a delayed enhancement. CONCLUSIONS: Three months after revascularization, delayed enhancement of dysfunctional myocardium is evident in patients without regional wall motion improvement, while the lack of delayed enhancement correlates with improvement of regional contractility.

Adult↗
PubMed2000

[Cardiac energy metabolism in heart valve diseases with 31P MR spectroscopy].

PURPOSE: Heart valve disease combined with left ventricular hypertrophy leads to derangements in cardiac energy metabolism, which can be detected non-invasively by 31P-MR-spectroscopy. The purpose of the present study was to examine whether the derangements in cardiac metabolism are reversible after surgical valve replacement. PATIENTS AND METHODS: 10 healthy volunteers and 10 patients with aortic stenosis (pressure gradients > 60 mmHg) were included. For assessment of energy metabolism, 31P-MR spectra were obtained with a double oblique 3D-CSI technique (voxel size 25 cm3). In 5 of 10 patients, follow-up examination was performed 3 months after surgical valve replacement (SVR). Left ventricular (LV) function was analyzed by cine MRI. RESULTS: Before SVR the myocardial phosphocreatine to adenosinetriphosphate (PCr-ATP) ratio was significantly (p = 0.0002) reduced to 0.80 +/- 0.25 in patients compared to 1.65 +/- 0.21 in volunteers. 3 months after SVR, LV mass had significantly (p = 0.04) decreased from 238 +/- 33 g to 206 +/- 47 g. At the same time a significant (p = 0.04) increase of the PCr-ATP ratio from 0.80 +/- 0.25 to 1.28 +/- 0.22 was observed. A slight, but not significant, reduction of the phosphodiester ATP ratio was observed before SVR, with a trend towards normalization after SVR. CONCLUSIONS: After SVR, the deranged energy metabolism shows a trend towards normalization. Further follow-up is necessary to determine whether complete normalization of the energetic derangement can be observed over longer periods of time following SVR.

Adult↗
PubMed2000

[MR tomography of the heart].

The introduction of magnetic resonance (MR) tomography has fundamentally changed radiological diagnosis for many diseases. Invasive digital subtraction angiography has already been widely replaced by noninvasive MR angiography for most of the vascular diseases. The rapid technical development of MR imaging in recent years has opened new functional imaging techniques. MR imaging of the heart allows simultaneous measurement of morphological and functional parameters in a single noninvasive examination without any radiation exposure. Because of the high spatial resolution and the reproducibility cine MR imaging is now the gold standard for functional analysis. With the improvement of myocardial perfusion and viability studies many diseases of the heart can be diagnosed in a single examination. MR spectroscopy is the only method which allows a view of the metabolism of the heart. New examinations for vascular imaging and flow quantification complete the goal of "one-stop-shop" imaging of the heart. MR imaging is the only diagnostic modality which allows a complete evaluation of many diseases of the heart with one technique, basic examination as well as follow-up studies. The very rapid improvement in MRI will overcome most of the limitations in the near future, especially concerning MR coronary angiography.

Cardiomyopathies↗
PubMed2000

Altered energy metabolism after myocardial infarction assessed by 31P-MR-spectroscopy in humans.

The value of 31P-magnetic resonance spectroscopy (MRS) as a possible tool to distinguish viable from non-viable tissue after myocardial infarction was analysed in humans. Fifteen patients 3 weeks after anterior myocardial infarction were studied with breath-hold cine MRI and 3D-CSI MRS (1.5 T system). 31P-spectra were obtained from infarcted as well as non-infarcted myocardium (voxel size 25 cm3 each). Gold standard for viability was recovery of regional function, as determined by a control MRI 6 months after revascularization. Ten age-matched healthy volunteers served as control group. No significant difference was found between the phosphocreatine to adenosinetriphosphate (PCr/ ATP) ratio of volunteers (SD 1.72+/-0.31) and non-infarcted septal myocardium of patients. Cine MRI demonstrated recovery of regional function in 10 patients, i. e. 10 patients showed viable and 5 non-viable myocardium. In viable myocardium, the PCr/ATP ratio was 1.47+/-0.38 (non-significant vs volunteers; p>0.05). In the 5 patients with akinetic myocardium, PCr peaks could not be detected. Therefore, calculation of PCr/ATP ratios was not possible. However, a significant reduction of the ATP signal-to-noise ratio (SNR) was observed (2.92+/-0.73 vs 6.68+/-0.80; patients vs volunteers; p<0.05). The SNR of ATP of akinetic regions may predict recovery of function after revascularization in patients with myocardial infarction.

Adenosine Triphosphate↗
PubMed2000

Age- and gender-specific differences in left and right ventricular cardiac function and mass determined by cine magnetic resonance imaging.

We examined possible age- and gender-specific differences in the function and mass of left (LV) and right (RV) ventricles in 36 healthy volunteers using cine gradient-recalled echo magnetic resonance imaging. Subjects were divided into four groups (nine men and nine women in each): men aged under 45 years (32 +/- 7), women aged under 45 (27 +/- 6), men aged over 45 (59 +/- 8), and women aged over 45 (57 +/- 9). Functional analysis of cardiac volume and mass and of LV wall motion was performed by manual segmentation of the endocardial and epicardial borders of the end-diastolic and end-systolic frame; both absolute and normalized (per square meter body surface area) values were evaluated. With age there was a significant decrease in both absolute and normalized LV and RV chamber volumes (EDV, ESV), while LV and RV masses remained unchanged. Gender-specific differences were found in cardiac mass and volume (for men and women, respectively: LV mass, 155 +/- 18 and 110 +/- 16 g; LV EDV, 118 +/- 27 and 96 +/- 21 ml; LV ESV, 40 +/- 13 and 29 +/- 9 ml; RV mass, 52 +/- 10 and 39 +/- 5 g; RV EDV, 131 +/- 28 and 100 +/- 23 ml; RV ESV, 53 +/- 17 and 33 +/- 15 ml). Normalization to body surface area eliminated differences in LV volumes but not those in LV mass, RV mass, or RV function. Functional parameters such as cardiac output and LV ejection fraction showed nonsignificant or only slight differences and were thus largely independent of age and gender. Intra- and interobserver variability ranged between 1.4% and 5.9% for all parameters. Cine magnetic resonance imaging thus shows age- and gender-specific differences in cardiac function, and therefore the evaluation of cardiac function in patients should consider age- and gender-matched normative values.

Adult↗
PubMed2000

[(23)sodium MRI for infarct imaging of the human heart].

PURPOSE: Sodium is elevated in acute/subacute myocardial infarction due to three distinct mechanisms: Breakdown of ion homeostasis with accumulation of intracellular sodium, extracellular edema formation and, during scar formation, increase of extracellular vs. intracellular space as cardiomyocytes are replaced by connective tissue. 23Na MRI has previously been shown to have the potential to demonstrate myocardial infarction in an animal model. Aim of this study was, therefore, to demonstrate myocardial infarction with the use of 23Na-MRI in patients. MATERIAL AND METHODS: 10 patients were examined 14 +/- 7 days after first myocardial infarction using a 23Na surface coil at 1.5 T. Double angulated short axis images of the entire heart were imaged using an ECG-triggered 3d-FLASH-sequence (FOV, 450 mm; matrix, 64 x 128; spatial resolution, 3.5 x 7 mm2; slice thickness, 16 mm; 32 acquisitions). Areas of elevated sodium signal intensity were correlated with infarct-related wall motion abnormalities imaged by Cine MRI in breathhold-technique. RESULTS: All patients showed an area of elevated sodium signal intensity that correlated well with the clinically determined localization of myocardial infarction as well as with regional wall motion abnormalities detected by Cine MRI. CONCLUSIONS: Elevated 23Na MR image signal intensity demonstrates subacute myocardial infarction in patients.

Aged↗
PubMed1999

Spiral CT angiography of renal arteries: comparison with angiography.

A prospective study was carried out to determine the accuracy of spiral CT angiography (CTA) in the detection of renal artery stenosis (RAS). Eighty-two patients with arterial hypertension underwent CTA and digital subtraction angiography (DSA) to exclude RAS. For CTA a contrast medium bolus of 100-150 ml (flow rate 3 ml/s) was injected. A 24 or 40 s CTA was started at the origin of the superior mesenteric artery after a delay time determined by test bolus injection (collimation = 2 mm, pitch = 1/1.5). For stenosis detection transverse images supported by maximum intensity projections (MIP) or multiplanar reconstruction projections were used. Of 197 renal arteries examined (including 33 accessory arteries), 34 RAS were visualized using DSA. With CTA, one hemodynamic RAS was missed and one additional hemodynamic RAS was found. Sensitivity/specificity was calculated to be 94 %/98 %. For hemodynamically relevant RAS (> 50 %) the sensitivity/specificity was 96 %/99 %. CTA additionally depicted five adrenal masses. The high accuracy rate of RAS detection thus allows the use of CTA as a screening method in patients with arterial hypertension to exclude a renovascular cause.

Adult↗
PubMed1999

[CINE-MRT for the study of the effects of regional left ventricular wall motion disorders on global heart function after a myocardial infarct and revascularization].

PURPOSE: To determine changes in global cardiac function and mass caused by infarct-associated regional wall motion abnormalities and to compare the changes after revascularization in patients with and without improvement of regional contractility. MATERIALS AND METHODS: 21 patients with regional left ventricular wall motion abnormalities and associated coronary artery stenoses requiring revascularization were examined with a Cine FLASH-2D sequence 26 +/- 12 days after their first myocardial infarction and re-examined three months after revascularization. Regional contractility and volumes and masses of both ventricles were determined. RESULTS: After revascularization, regional wall motion improvement led to decreased left ventricular volumes and improved ejection fractions, whereas patients with persisting wall motion defects showed unchanged left ventricular functional parameters. Comparing both groups of patients, the patients with improvement of regional contractility revealed lower end-systolic volumes and higher ejection fractions at follow-up. Cardiac masses and right ventricular parameters were not different, patients with a depressed right ventricular ejection fraction showed improvement at follow-up. DISCUSSION: After myocardial infarction, revascularization of the infarct-related coronary artery leads to an improvement of left ventricular function only if there is also an improvement of regional contractility. An effect on right ventricular function was not observed three months after the first small- or middle-sized myocardial infarction.

Adult↗
PubMed1999

[The quantification of energy-rich phosphates in healthy and damaged heart muscle by SLOOP 31P-MR spectroscopy. Spatial localization with optimal pointspread function].

PURPOSE: A quantitative 31P-MR-spectroscopic technique was used to assess the energy metabolism in healthy and diseased myocardium. METHODS: 31P spectra were acquired on a 1.5 T scanner using a 3D-chemical shift imaging technique. Based on the anatomical information provided by 1H images, SLOOP (Spatial Localization with Optimal Pointspread Function) allows to obtain spectra from defined compartments. With SLOOP a free voxel shape with adaption to anatomic structures, e.g. the myocardium, is possible. Absolute values for phosphocreatine (PCr) and adenosine triphosphate (ATP) were determined using an external standard. RESULTS: 31P-spectra showed only minimal contamination by surrounding tissue. The standard deviation for the determined values of healthy volunteers was low. Compared to healthy volunteers, reduced PCr and ATP concentrations were seen for dilative cardiomyopathies and coronary artery disease and unchanged concentrations were observed for hypertensive heart disease. CONCLUSION: 31P-MR spectroscopy with SLOOP allows a non-invasive, quantitative analysis of cardiac energy metabolism.

Adenosine Triphosphate↗
PubMed1999

[3-dimensional MR coronary angiography in the navigator technic for the primary diagnosis of coronary heart disease: a comparison with conventional coronary angiography].

PURPOSE: Evaluation of three-dimensional MR coronary angiography with the navigator technique for the primary diagnosis of coronary artery disease (CAD) in patients with chest pain. MATERIALS AND METHODS: In this prospective study 20 patients with chest pain were examined with MR coronary angiography and conventional angiography. The three-dimensional MR coronary angiography was performed using a 1.5 T scanner with an ECG-triggered 3D-FLASH-sequence and retrospective respiratory gating in the navigator technique. The MR coronary angiography was evaluated by two radiologists blinded to the results of the conventional coronary angiography. RESULTS: One patient was excluded from further evaluation due to reduced image quality. Conventional coronary angiography excluded CAD in 8/19 patients, 11/19 patients overall showed 20 stenoses (> 50%) or occlusions. With MR coronary angiography, CAD was correctly excluded in 7 patients, one patient was false positive, one patient was false negative. 14/20 stenoses (> 50%) or occlusions were detected, 5 stenoses were diagnosed false positive. Sensitivity and specificity for primary diagnosis of CAD or detection of coronary artery stenoses were 91% and 88% or 70% and 91%, respectively. DISCUSSION: Using MR coronary angiography with the navigator technique in the primary evaluation of CAD, the diagnosis of stenoses or occlusions of the main coronary arteries is feasible.

Adult↗
PubMed1998

[3-dimensional MR coronary angiography with navigator technique: imaging of the proximal course of a coronary artery anomaly].

Congenital coronary artery anomalies are found in 0.3 to 1.3% of patients and can cause ischemic heart disease or sudden cardiac death, especially if the anomalous coronary artery courses between the aortic root and the pulmonary artery. Identification of the anatomic course of the anomalous vessel is not always feasible by conventional radiographic coronary angiography. With MR coronary angiography not only flowing blood but also the vessel anatomy can be imaged. In previous studies, a two-dimensional gradient-echo sequence during breathhold was used demanding both cooperation of the patient and operator skill. The navigator technique reduces respiratory artifacts by retrospective respiratory gating on the diaphragm's position, obviating the need for breathhold studies. Furthermore, the three-dimensional MR coronary angiography enables post-processing using the Volume Rendering Technique for evaluation of three-dimensional view. We report on the use of this technique for the identification of the course of anomalous coronary arteries in two patient cases.

Artifacts↗