Biomedical subjects

L J Kroft

Publications and source records attributed to L J Kroft.

9 recordsLinked to original sources

PubMed2000

Patients with pulmonary fibrosis: cardiac function assessed with MR imaging.

PURPOSE: To detect abnormalities in cardiac function by using magnetic resonance (MR) imaging in patients with mild to moderate pulmonary fibrosis and to evaluate the relationship between pulmonary function and cardiac function. MATERIALS AND METHODS: Sixteen patients were compared with 16 sex- and age-matched healthy control subjects. Systolic function was assessed by using multisection multiphase cine MR imaging. Diastolic function was assessed with flow-sensitive MR imaging across the mitral and tricuspid valves. MR imaging results were compared with the severity of impairment in pulmonary function. RESULTS: Biventricular systolic function and left ventricular diastolic function were normal in patients, but right ventricular diastolic function was significantly impaired versus that of control subjects, with a ratio of peak flow during early diastolic (E) filling to peak flow during atrial contraction (A) of 0.85 +/- 0.40 versus 1.28 +/- 0.50 (P =.035). Biventricular E/A ratios were strongly correlated to age in patients and control subjects. The right ventricular E/A ratio in patients corresponded with values that are normally expected in people 20 years older. Diastolic left and right ventricular functions were significantly correlated with each other. There was no relationship between pulmonary function and cardiac function. CONCLUSION: Impairment of right ventricular diastolic function was found by using MR imaging in patients with mild to moderate pulmonary fibrosis, whereas left ventricular diastolic function and biventricular systolic function were preserved.

Adult↗

PubMed1999

Postsurgical course of patients with congenitally corrected transposition of the great arteries.

Because congenitally corrected transposition is a rare congenital anomaly, little is known about the prognosis of patients with this syndrome. The present study evaluated the functional status and clinical course of 73 patients (42 male and 31 female) aged 10 days to 73 years. Follow-up was 1 week to 37 years (mean 12.7 years). Particular attention was paid to the systemic right ventricle, considering the current controversies about long-term right ventricular function. Survival of patients with this condition in general was significantly below normal. The total mortality rate was 11% (8 patients) after a mean follow-up of 12.7 years (range 10 days to 37 years). Mean age at death was 18.5 years (range 6 days to 63 years). The mean age of the survivors at latest follow-up was 21.4 years (range 4 months to 73 years). In most patients, right ventricular function deteriorated and tricuspid valve regurgitation increased, which began at a very young age. Patients without associated lesions developed complications at a higher age compared with the total group. Right ventricular and tricuspid valvular function deteriorated more frequently in patients following intracardiac operation (28% and 52%, respectively) compared with patients undergoing palliative intervention (16%) or no surgery at all (28%). We conclude that survival of patients with this condition is substantially reduced compared with the natural history of an age- and gender-matched general population. This could be explained by the associated cardiac defects, but also by the anatomic condition itself.

Adolescent↗

PubMed1999

Equilibrium phase MR angiography of the aortic arch and abdominal vasculature with the blood pool contrast agent CMD-A2-Gd-DOTA in pigs.

Meglumine-carboxymethyldextran-ethylenediamino-gadoterate (CMD-A2-Gd-DOTA) was evaluated as a blood pool contrast agent for magnetic resonance angiography (MRA). MRA of large body vasculature was performed in seven pigs using a gradient-echo sequence at 1.5 T before and after 0.05 mmol/kg CMD-A2-Gd-DOTA injection. The signal- and contrast-to-noise ratios (SNRs, CNRs) were measured, as well as the pharmacokinetic clearance pattern. CMD-A2-Gd-DOTA visualized the vasculature with a high SNR and CNR for over 110 minutes after injection, but for the renal arteries the CNR was only significant within 15 minutes. Image quality was maximum within 15 minutes, producing enhancement (mean +/- SD) as follows: aortic arch 738 +/- 272%, abdominal aorta 393 +/- 123%, left renal artery 202 +/- 95%, right renal artery 248 +/- 107%, inferior vena cava 371 +/- 129%, and portal vein 513 +/- 145%, all P values < or =0.001. The clearance pattern was triphasic. Due to the excellent enhancement of vasculature without background enhancement, CMD-A2-Gd-DOTA is potentially a useful MR blood pool contrast agent for equilibrium phase MRA.

Abdomen↗

PubMed1999

Blood pool contrast agent CMD-A2-Gd-DOTA-enhanced MR imaging of infarcted myocardium in pigs.

The purpose of this study was to assess the ability of the new blood pool contrast agent meglumine-carboxymethyldextran-ethylenediamino-gadoterate (CMD-A2-Gd-DOTA) to depict acute occlusive myocardial infarction (AMI). First-pass gradient-echo and delayed spin-echo magnetic resonance imaging (MRI) was performed 5 days after induction of AMI in a pig model. MRI was correlated with pathology. First-pass imaging with CMD-A2-Gd-DOTA allowed detection of infarcted myocardium in all pigs (n = 7). The infarction was recognized as a black spot on MRI as well as on a parametric image. The signal intensity (SI) amplitudes of normal versus infarcted myocardium were 80.55 +/- 18.61 versus 8.48 +/- 15.50 on MRI and 81.62 +/- 18.50 versus 1.61 +/- 3.73 on the parametric image (both P values < 0.001. The contrast ratio between normal and infarcted myocardium was not significantly improved on spin-echo MRI, suggesting largely intact vascular integrity outside the occluded area. CMD-A2-Gd-DOTA is useful for depicting occlusive myocardial infarction by first-pass MRI. Spin-echo imaging is promising in assessing vascular integrity. J. Magn. Reson. Imaging 1999;10:170-177.

Analysis of Variance↗

PubMed1999

Blood pool contrast agents for cardiovascular MR imaging.

The distribution and elimination of contrast agents is mainly determined by their size. First-pass perfusion with the use of blood pool contrast agents (BPCAs) and/or rapid clearance blood-pool-like contrast agents may allow quantitative myocardial perfusion evaluation in patients. This requires contrast bolus injection with a very fast injection speed. A major profit from BPCAs is expected for magnetic resonance angiography (MRA). The persistent signal-enhancing effects of BPCAs allow for a longer acquisition time window, which may be used to increase both the signal-to-noise ratio and/or image resolution. This is of paramount importance for coronary imaging, in which high-resolution imaging is desired. Moreover, the improved acquisition time window can be used to make multiple scans after one contrast injection. The role of ultrasmall paramagnetic iron oxide particles (USPIOs) for MRA is not clear yet, as they are limited by T2* effects at higher doses. Several safety aspects have to be taken into account before BPCAs are applied in humans, for whom toxicity caused by the injection speed is a concern.

Cardiovascular Diseases↗

PubMed1999

Infarcted myocardium in pigs: MR imaging enhanced with slow-interstitial-diffusion gadolinium compound P760.

PURPOSE: To assess the value of P760, a gadolinium chelate with slow interstitial diffusion and high relaxivity, for magnetic resonance (MR) imaging of acute myocardial infarction in pigs. MATERIALS AND METHODS: First-pass gradient-echo MR imaging and spin-echo MR imaging were performed with P760 and then with gadoterate meglumine in eight pigs with occlusive acute myocardial infarction. P760 signal intensity enhancement and clearance were compared with those of gadoterate meglumine. RESULTS: The first-pass enhancement ratio of P760 in normal myocardium was higher than that in infarcted myocardium (1.37 +/- 0.06 [SEM] vs 1.05 +/- 0.03, P = .03). The myocardial first pass showed a blood pool-like curve for P760. The blood pool enhancement ratio 40 seconds after injection was higher for P760 than for gadoterate meglumine (left ventricular cavity, 1.75 +/- 0.06 vs 1.45 +/- 0.06, P = .009). Spin-echo MR imaging showed improved contrast between normal and infarcted myocardium after P760 administration: The ratio before contrast material administration was 0.21 +/- 0.03, that at 15 minutes was 0.48 +/- 0.05 (P = .002), and that at 25 minutes was 0.47 +/- 0.07 (P = .003). CONCLUSION: P760 is an MR imaging contrast agent characterized by low diffusion, a blood pool effect soon after low-dose administration, and fast elimination. This agent is useful for improved myocardial perfusion MR imaging of acute myocardial infarction.

Animals↗

PubMed1999

Biventricular diastolic cardiac function assessed by MR flow imaging using a single angulation.

PURPOSE: To evaluate whether one single angulation is reliable for biventricular diastolic MR flow measurements across both the mitral and tricuspid valves. MATERIAL AND METHODS: MR flow imaging was performed in 14 healthy volunteers and 14 patients with pulmonary fibrosis. Flow curve parameters were calculated from the mitral valve in mitral valve angulation, the tricuspid valve in tricuspid valve angulation, and also from the mitral valve in tricuspid valve angulation and the tricuspid valve in mitral valve angulation. RESULTS: For flow through the mitral valve, there were no significant differences between angulation set parallel to the mitral valve and angulation set parallel to the tricuspid valve for the diastolic inflow volume, the E-peak and the E:A ratio as measured in healthy volunteers and patients. The tricuspid valve flow was imaged well when the angulation was set parallel to the tricuspid valve, but not when angulation was set parallel to the mitral valve. The results indicate that the inflow volumes, the E-peak, and the E:A peak ratios across the mitral valve and tricuspid valve can be obtained using one single angulation which is set parallel to the tricuspid valve. CONCLUSION: Biventricular diastolic flow measurements can be obtained using one single angulation set parallel to the tricuspid valve.

Blood Flow Velocity↗

PubMed1998

Ultrasmall superparamagnetic particles of iron oxide (USPIO) MR imaging of infarcted myocardium in pigs.

The purpose of this study is to assess the potential value of ultrasmall superparamagnetic iron oxide (USPIO) for the detection of acute myocardial infarction by magnetic resonance (MR) imaging. Spin-echo magnetic resonance imaging of the heart was performed before, immediately after, and approximately 35 and 90 min after 30 micromol Fe/kg of USPIO administration in seven pigs with surgically induced myocardial infarction. Gradient-echo sequences were used to identify contraction abnormalities at the site of infarction. Myocardial signal intensities were measured using region-of-interest analysis in normal and infarcted myocardium. In addition, liver and lung signal intensities were measured. Pathologic correlation was performed after sacrificing the animals. The infarct area was located with wall-motion analysis. The site of infarction was confirmed at pathologic examination. The signal-intensity ratio between infarcted and normal myocardium was not significantly changed after USPIO administration at equilibrium stages (immediately after injection p = 0.64, at 35 min p = 0.32, at 90 min p = 0.73). The signal intensity of the liver decreased significantly after contrast administration (p < 0.05). For the lung, the change in signal intensity after USPIO administration was not significant. This pig model is well suited to study wall motion abnormalities after induction of acute myocardial infarction. USPIO-enhanced magnetic resonance imaging does not improve the visualization of acute myocardial infarction at equilibrium stage.

Animals↗

PubMed1993

The effect of ticlopidine upon plasma fibrinogen levels in patients undergoing suprapubic prostatectomy.

The mechanisms of the antithrombotic effect of the platelet aggregation inhibiting agent Ticlopidine might include a decrease of the plasma fibrinogen level. The effect of ticlopidine on increased fibrinogen synthesis following trauma, such as surgery, is however not known. 46 patients who underwent suprapubic prostatectomy were randomized to receive either (group A) Ticlopidine (2 x 250 mg daily) from the second preoperative day until the seventh postoperative day or (group B) placebo up till the day of surgery and further acenocoumarol against post-operatively and observed that the level and in particular the rise of the plasma fibrinogen concentration was not different in the two groups. It is concluded that compared with the standard treatment in group B ticlopidine does not influence trauma-induced fibrinogen increase.

Acenocoumarol↗