Biomedical subjects

N Wilke

Publications and source records attributed to N Wilke.

At least 37 records · Page 2Linked to original sources

PubMed1998

Magnetic resonance quantification of the myocardial perfusion reserve with a Fermi function model for constrained deconvolution.

The myocardial perfusion reserve, defined as the ratio of hyperemic and basal myocardial blood flow, is a useful indicator of the functional significance of a coronary artery lesion. Rapid magnetic resonance (MR) imaging for the noninvasive detection of a bolus-injected contrast agent as a MR tracer is applied to the measurement of regional tissue perfusion during rest and hyperemia, in patients with microvascular dysfunction. A Fermi function model for the distribution of tracer residence times in the myocardium is used to fit the MR signal curves. The myocardial perfusion reserve is calculated from the impulse response amplitudes for rest and hyperemia. The assumptions of the model are tested with Monte Carlo simulations, using a multiple path, axially distributed mathematical model of blood tissue exchange, which allows for systematic variation of blood flow, vascular volume, and capillary permeability. For a contrast-to-noise ratio of 6:1, and over a range of flows from 0.5 to 4.0 ml/min per g of tissue, the ratio of the impulse response amplitudes for hyperemic and basal flows is linearly proportional to the ratio of model blood flows, if the mean transit time of the input function is shorter than approximately 9 s. The uncertainty in the blood flow reserve estimates grows both at low (< 1.0 ml/min/g) and high (> 3-4 ml/min/g) flows. The predictions of the Monte Carlo simulations agree with the results of MR first pass studies in patients without significant coronary artery lesions and microvascular dysfunction, where the perfusion reserve in the territory of the left anterior descending coronary artery (LAD) correlates linearly with the intracoronary Doppler ultrasound flow reserve in the LAD (r = 0.84), in agreement with previous PET studies.

Capillaries↗

PubMed1997

MR first pass imaging: quantitative assessment of transmural perfusion and collateral flow.

Recent advances with fast switching gradient coils, and the optimization of magnetic resonance techniques for multislice imaging have made it possible to apply models of contrast agent transit for the quantification of myocardial perfusion, and determination of the transmural distribution of blood flow. This article summarizes some of these recent developments and presents examples of quantitative, multi-slice myocardial perfusion imaging studies in patients and animal models. Multi-slice, true first pass imaging, with high temporal resolution, and T1-weighted, arrhythmia insensitive contrast enhancement is used for the quantification of perfusion changes accompanying mild to severe ischemia. The first pass imaging technique and the modeling approach are sufficiently robust for fitting of tissue residue curves corresponding to a wide, physiologically realistic range of myocardial blood flows. In animals this was validated by comparison to blood flow measurements with radiolabeled microspheres as gold standard. It is demonstrated that with the proposed modeling approach one can determine the myocardial perfusion reserve from two consecutive MR first pass measurements under resting and hyperemic conditions. In patients with microvascular dysfunction the MR studies show for the first time that the myocardial perfusion reserve correlates with Doppler flow measurements (linear regression with slope of 1.02 +/- 0.09; r = 0.80). Since perfusion limitations usually begin in the subendocardium as coronary flow is gradually reduced, first pass imaging with the prerequisitie spatial and temporal resolution allows early detection of a mild coronary stenosis.

Animals↗

PubMed1997

Myocardial perfusion reserve: assessment with multisection, quantitative, first-pass MR imaging.

PURPOSE: To demonstrate the feasibility of determining myocardial blood flow changes and the myocardial perfusion reserve with magnetic resonance (MR) first-pass imaging, to validate the MR results by means of comparison with radiolabeled microsphere flow measurements in an animal model, and to compare the coronary flow reserve with the perfusion reserve at MR imaging in patients with hemodynamically nonsignificant coronary lesions and angina. MATERIALS AND METHODS: Arrhythmia-insensitive, first-pass, multisection, T1-weighted MR imaging with contrast agent enhancement was performed in eight pigs with acute ischemia and in eight adult patients (six women, two men). In the pigs, microsphere flow measurements were obtained in parallel with the MR measurements. In the patients, the coronary flow reserve was measured with an intracoronary Doppler flow ultrasound probe for comparison with the MR perfusion reserve. RESULTS: In the animal studies, there was linear correlation between MR perfusion indexes and the microsphere flow measurements (r = .88, P < .01). In the patients, the regional perfusion reserve matched the coronary flow reserve (linear regression with a slope of 1.02 +/- 0.09, r = .80). CONCLUSION: The myocardial perfusion reserve can be quantified with first-pass MR imaging. In patients with microvascular dysfunction, the myocardial perfusion reserve matches the reduced coronary flow reserve.

Animals↗

PubMed1996

Functional and bioenergetic consequences of postinfarction left ventricular remodeling in a new porcine model. MRI and 31 P-MRS study.

BACKGROUND: The underlying mechanisms by which left ventricular remodeling (LVR) leads to congestive heart failure (CHF) are unclear. This study examined the functional and bioenergetic abnormalities associated with postinfarction ventricular remodeling in a new, large animal model. METHODS AND RESULTS: Remodeling was induced by circumflex coronary artery ligation in young pigs. LV mass, volume, ejection fraction (EF), the ratio of scar surface area to LV surface area, and LV wall stresses were calculated from magnetic resonance imaging anatomic data and simultaneously measured LV pressure. Hemodynamics, transmural blood flow, and high-energy phosphates (spatially localized 31P-nuclear magnetic resonance) were measured under basal conditions, during hyperperfusion induced by pharmacological vasodilation with adenosine, and during pyruvate infusion (11 mg/kg per minute IV). Six of 18 animals with coronary ligation developed clinical CHF while the remaining 12 animals had LV dilation (LVR) without CHF. The results were compared with 16 normal animals. EF decreased from 55.9 +/- 5.6% in normals to 34.6 +/- 2.3% in the LVR group (P < .05) and 24.2 +/- 2.8% in the CHF group (P < .05 versus LVR). The infarct scar was larger in CHF hearts than in LVR hearts (P < .05). In normals, LV myocardial creatine phosphate (CP)/ATP ratios were 2.10 +/- 0.10, 2.06 +/- 0.16, and 1.92 +/- 0.12 in subepicardium (EPI), mid myocardium (MID), and subendocardium (ENDO), respectively. In LVR hearts, the corresponding ratios were decreased to 1.99 +/- 0.13, 1.80 +/- 0.14, and 1.57 +/- 0.15 (ENDO P < .05 versus normal). In CHF hearts, CP/ATP ratios were 1.41 +/- 0.14, 1.33 +/- 0.15, and 1.25 +/- 0.15; (P < .05 versus LVR in EPI and MID). The calculated myocardial free ADP levels were significantly increased only in CHF hearts. CONCLUSIONS: Bioenergetic abnormalities in remodeled myocardium are related to the severity of LV dysfunction, which, in turn, is dependent on the severity of the initiating myocardial infarction.

Adenosine Triphosphate↗

PubMed1996

Interaction of ethanol with inducers of glucose-regulated stress proteins. Ethanol potentiates inducers of grp78 transcription.

GRP78, a molecular chaperone expressed in the endoplasmic reticulum, is a "glucose-regulated protein" induced by stress responses that deplete glucose or intracisternal calcium or otherwise disrupt glycoprotein trafficking. Previously we showed that chronic ethanol exposure increases the expression of GRP78. To further understand the mechanism underlying ethanol regulation of GRP78 expression, we studied the interaction between ethanol and classical modulators of GRP78 expression in NG108-15 neuroblastoma x glioma cells. We found that, in addition to increasing basal levels of GRP78 mRNA ("induction"), ethanol produced greater than additive increases in the induction of GRP78 mRNA by the "classical" GRP inducers A23187, brefeldin A, and thapsigargin ("potentiation"). Both the ethanol induction and potentiation responses modulated grp78 gene transcription as determined by stable transfection analyses with the rat grp78 promoter. Ethanol potentiated the action of all classical inducers of grp78 transcription that were studied. In contrast, co-treatment with the classical GRP inducers thapsigargin and tunicamycin produced only simple additive increases in grp78 promoter activity. Transient transfection studies with deletion mutants of the rat grp78 promoter showed that cis-acting promoter sequences required for ethanol induction differ from those mediating responses to classical GRP inducers. Furthermore, linker-scanning mutations of the grp78 promoter suggested that the ethanol potentiation response required a cis-acting promoter element different from those involved in induction by ethanol or classical inducing agents. While the ethanol induction response required 16-24 h to be detectable, ethanol potentiation of thapsigargin occurred within 6 h. The potentiation response also decayed rapidly after ethanol removal. In addition, the protein kinase A inhibitor Rp-cAMPS and protein phosphatase inhibitor okadaic acid both increased ethanol potentiation of thapsigargin while Sp-cAMPS, an activator of protein kinase A, decreased ethanol potentiation. Taken together, our findings suggest two mechanisms by which ethanol regulates grp78 transcription, both differing from the action of classical GRP inducers such as thapsigargin. One mechanism (potentiation) involves a protein phosphorylation cascade and potentiates the action of classical GRP inducers. In contrast, GRP78 induction by ethanol involves promoter sequences and a mechanistic pathway separate from that of the ethanol potentiation response or classical GRP78 inducers. These studies show that ethanol produces a novel and complex regulation of grp78 transcription which could be of particular importance during neuronal exposure to GRP-inducing stressors as might occur with central nervous system injury.

Animals↗

PubMed1996

Myocardial perfusion and function in dogs with moderate coronary stenosis.

MRI studies of first-pass contrast enhancement with polylysine-Gd-DTPA and myocardial tagging using spatial modulation of magnetization (SPAMM) were performed to assess the feasibility of a combined regional myocardial blood flow and 2D deformation exam. Instrumented closed-chest dogs were imaged at a baseline control state (Cntl) followed by two interventions: moderate coronary stenosis (St) achieved by partial occlusion of the left anterior descending (LAD) and moderate coronary stenosis with dobutamine loading (StD). Hypoperfusion of the anterior region (ANT) of the myocardium (LAD distribution) relative to the posterior wall (POS) based on the upslope of the signal intensity time curve from the contrast-enhanced MR images was demonstrated only with dobutamine loading (ANT:POS Cntl = 1.077 +/- 0.15 versus ANT:POS StD = 0.477 +/- 0.11, P < 0.03) and was confirmed with radiolabeled microspheres measurements (ANT:POS Cntl = 1.18 +/- 0.2 ml/min/g versus ANT:POS StD = 0.44 +/- 0.1 ml/min/g; P < 0.002). Significant changes in regional myocardial shortening were only seen in the StD state (P < 0.02); the anterior region showed impaired myocardial shortening with dobutamine loading (P = NS), whereas the nonaffected POS region showed a marked increase in shortening when compared with Cntl (Cntl = 0.964 +/- 0.02 versus StD = 0.884 +/- 0.03; P < 0.001). These results demonstrate that an integrated quantitative assessment of regional myocardial function and semiquantitative assessment of myocardial blood flow can be performed noninvasively with ultrafast MRI.

Animals↗

PubMed1996

Modeling regional myocardial flows from residue functions of an intravascular indicator.

The purpose of the present study was to determine the accuracy and the sources of error in estimating regional myocardial blood flow and vascular volume from experimental residue functions obtained by external imaging of an intravascular indicator. For the analysis, a spatially distributed mathematical model was used that describes transport through a multiple-pathway vascular system. Reliability of the parameter estimates was tested by using sensitivity function analysis and by analyzing "pseudodata": realistic model solutions to which random noise was added. Increased uncertainty in the estimates of flow in the pseudodata was observed when flow was near maximal physiological values, when dispersion of the vascular input was more than twice the dispersion of the microvascular system for an impulse input, and when the sampling frequency was < 2 samples/s. Estimates of regional blood volume were more reliable than estimates of flow. Failure to account for normal flow heterogeneity caused systematic underestimates of flow. To illustrate the method used for estimating regional flow, magnetic resonance imaging was used to obtain myocardial residue functions after left atrial injections of polylysine-Gd-diethylenetriaminepentaacetic acid, an intravascular contrast agent, in anesthetized chronically instrumental dogs. To test the increase in dispersion of the vascular input after central venous injections, magnetic resonance imaging data obtained in human subjects were compared with left ventricular blood pool curves obtained in dogs. It is concluded that if coronary flow is in the normal range, when the vascular input is a short bolus, and the heart is imaged at least once per cardiac cycle, then regional myocardial blood flow and vascular volume may be reliably estimated by analyzing residue functions of an intravascular indicator, providing a noninvasive approach with potential clinical application.

Animals↗

PubMed1995

Myocardial tagging with B1 insensitive adiabatic DANTE inversion sequences.

A new technique, based on adiabatic delays alternating with mutations for tailored excitation (DANTE) inversion sequences, is presented for generating uniform contrast tags across the myocardial wall even in the presence of B1 inhomogeneities. The utility of this pulse was demonstrated using a surface coil for both transmission and signal reception in phantom and animal heart tagging studies. The experimental data demonstrated uniform grid contrast over a sixfold variation of B1 magnitude, sharp tagging profiles, and the ability to follow the cardiac wall motion through the deformation of the fine rectangular tagging grid at different phases throughout the cardiac cycle.

Animals↗

PubMed1995

Fast anatomical imaging of the heart and assessment of myocardial perfusion with arrhythmia insensitive magnetization preparation.

A new contrast preparation based on modified driven equilibrium Fourier transfer is introduced and evaluated for generation of T1-weighted images for assessment of the myocardial perfusion with contrast agent first-pass kinetics. The new preparation scheme produces T1 contrast with insensitivity to arrhythmias in prospectively triggered sequential imaging thereby eliminating one of the major sources of problems in potential patient studies with previously employed contrast preparations schemes.

Algorithms↗

PubMed1994

Effects of alcohol on gene expression in neural cells.

Our studies in the NG108-15 neuroblastoma x glioma cell line previously showed that the molecular chaperonin, Hsc70, is an ethanol-responsive gene (EtRG) regulated at the level of transcription by ethanol. We recently identified two related molecular chaperonins, GRP94 and GRP78, as EtRGs with GRP94 mRNA abundance being induced by ethanol more than three-fold vs. control. Stable transfection studies show that GRP78 transcription is also regulated by ethanol and that ethanol also potentiates GRP78 induction by classical inducing agents such as tunicamycin. Recently, we have found that ethanol induction of Hsc70 may require cis-acting promoter sequences recognized by the DNA-binding protein Sp1. Chronic ethanol exposure does not alter Sp1 DNA-binding activity, thus suggesting a possible ethanol-induced post-translational modification that activates Sp1 function. We predict that the molecular mechanisms underlying ethanol regulation of Hsc70, GRP94 and GRP78 may be similar since they have related functions. GRP94 and GRP78 (GRP94/78) are known to be induced by agents which inhibit glycoprotein processing or deplete endoplasmic reticulum stores of calcium. In turn, induction of GRP78 expression is known to selectively alter the transport of glycoproteins and produce "tolerance" to depletion of sequestered intracellular calcium. The regulation of these genes by ethanol could thus relate to the known effects of ethanol on calcium homeostasis and protein trafficking. The actions of ethanol on chaperonin gene expression may have important mechanistic implications for CNS adaptation to ethanol, particularly if other EtRGs share the same regulatory mechanisms.

Animals↗

PubMed1994

[Quantitative evaluation of myocardial perfusion with ultrafast magnetic resonance tomography].

With the advent of ultrafast Magnetic Resonance Imaging (MRI), it is now possible to produce images with high temporal resolution. This gives the opportunity to record the passage of the paramagnetic contrast material Gadolinium-DTPA through the tissue of the heart muscle, yielding information on regional myocardial perfusion. We assessed the accuracy of MRI to detect and quantify reductions in coronary flow secondary to stenosis in dogs and patients. Regional blood flow was measured in dogs by left atrial injection of microspheres labeled with different radioactive isotopes. Signal intensity (SI) curves were generated in regions of interest over the myocardium and the cavum of the left ventricle. A newly developed two-compartment model based on the indicator-dilution method was used for interpretation of the SI-curves. In an optimization process the free parameters of the model equation were fitted to the measured SI-curves. The following flow parameters were determined: model parameter Q*, time to peak intensity (T), maximum signal intensity (SImax) and mean transit time (MTT) as calculated from a gamma variate fit. Absolute blood flow values were calculated for the parameters MTT and Q* assuming that the intravascular volume represents 10% of the total myocardial tissue volume. Measurements were performed on a 1.5 T Magnetom SP (Siemens AG, Erlangen) using a Turbo Flash sequence (TR = 6.5 ms, TE = 3 ms, TI = 100 ms, Flip Winkel = 9 degrees). Endsystolic images (voxel size = 1.8, 2.7, 15 mm3) were taken with an 18-cm Helmholtz surface coil in the short-axis view. A Gd-DTPA bolus (0.05 mmol/kg) was injected into the left atrium of 3 anesthetized closed-chest dogs. From the myocardial SI-curves the different parameters of myocardial perfusion were compared with flow assessed by microsphere injection over a wide range of myocardial blood flows (from 0.04 ml/min/g to 7.6 ml/min/g). A third-order polynominal fit showed a good correlation for the parameter Q* and MTT, whereas T and SImax were found to have a poor correlation. The linear regression analysis for a limited range of < 2 ml/min/g showed a superior estimation of myocardial perfusion for the parameter Q* than MTT. Blood flow > 2 ml/min/g was significantly underestimated by the MRT-measurements, but the parameter Q* showed the smallest amount of the divergent changes.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

PubMed1994

Concepts of myocardial perfusion imaging in magnetic resonance imaging.

Based on the major innovations in ultrafast magnetic resonance (MR) imaging in recent years, myocardial perfusion imaging with MR has become the focus of many investigators. Two major approaches to myocardial perfusion imaging involve either exogenous or endogenous contrast agents. For the first category of perfusion experiments, we review the characteristics of the common contrast agents and MR techniques for experimental and clinical first-pass studies and in particular address the question of extracting quantitative estimates for myocardial blood flow (milliliters per minute per gram) and volume (milliliters per gram). We demonstrated quantitative perfusion analysis using intravascular relaxation agents and heavily T1-weighted ultrafast gradient echo sequences. Signal time curves need to be transformed to content time curves and the resulting residue functions were analyzed with a multiple-pathway, axially distributed perfusion model. These preliminary results suggest that quantitative assessment of myocardial perfusion is feasible, but additional studies should provide further confidence for this novel MR approach. The exact sensitivity and specificity of MR first-pass imaging in conjunction with extracellular contrast agents in patient studies and its diagnostic accuracy as judged against coronary angiography and scintigraphic perfusion imaging remain yet undefined. The second category of perfusion experiments does not require exogenous contrast agents and has not yet been tested in patient studies. Progress is reported on several MR perfusion-sensitive methods that use the tissue water as an endogenous contrast agent in combination with magnetization transfer techniques as well as paramagnetic deoxyhemoglobin for measuring tissue oxygenation using heavily T2*-weighted sequences for blood oxygen-level-dependent contrast. Possible future directions and developments toward further improvements for MR myocardial perfusion measurements and contraction-perfusion matching are also addressed.

Blood Volume↗

PubMed1994

Ethanol-responsive genes in neural cells include the 78-kilodalton glucose-regulated protein (GRP78) and 94-kilodalton glucose-regulated protein (GRP94) molecular chaperones.

Previously we found that ethanol increases expression of the constitutive 70-kDa heat shock protein (Hsc70) in NG108-15 neuroblastoma x glioma cells. We suggested that known ethanol actions on cellular protein trafficking may relate to Hsc70 induction because Hsc70 functions as a molecular chaperone. Here we use a subtractive hybridization protocol to isolate ethanol-responsive genes (EtRGs). Northern blot hybridization verified ethanol-induced increases in mRNA abundance for five cDNA clones isolated from ethanol-treated NG108-15 neuroblastoma x glioma cells. DNA sequence analysis identified one EtRG as 94-kDa glucose-regulated protein (GRP94), a member of the "glucose-responsive" subgroup of stress proteins. Other identified EtRGs included an insulin-induced growth-response protein gene and an intracisternal A-type particle gene. Sequence analysis of the remaining two EtRGs showed no homology in DNA sequence databases. All EtRGs showed wide tissue expression, except SL64, which was not detected in Northern blot analyses of adult mouse or rat tissues. Ethanol also increased mRNA abundance for 78-kDa glucose-regulated protein (GRP78), a molecular chaperone known to function in glycoprotein trafficking and usually coordinately regulated with GRP94. However, ethanol induced GRP94 more than GRP78, a pattern distinct from those of other inducers of these genes. All EtRGs, including GRP94 and GRP78, showed similar ethanol concentration-dependent increases in mRNA abundance. In contrast, thapsigargin and other inducers of glucose-responsive proteins increased GRP94 and GRP78 mRNA levels without altering expression of other EtRGs. Our studies demonstrate that several molecular chaperones constitute a subset of EtRGs. Ethanol appears to regulate these EtRGs by a unique mechanism, rather than one shared by classical inducers of stress proteins.

Carrier Proteins↗

PubMed1993

Contrast-enhanced first pass myocardial perfusion imaging: correlation between myocardial blood flow in dogs at rest and during hyperemia.

The sensitivity of contrast-enhanced MR first pass perfusion imaging in detection and quantification of hypoperfused myocardium was evaluated using an instrumented, closed-chest dog model where graded regional hypoperfusion was induced by applying predetermined levels of stenosis to the left anterior descending artery (LAD). All measurements were performed at rest and under stress induced by dipyridamole (DIP). Myocardial perfusion was assessed both with MR and radiolabeled microspheres injected immediately before the administration of the MR contrast agent. Ultrafast MR imaging was performed using a Turbo FLASH sequence with a 180 degrees inversion prepulse. A Gd-DTPA bolus was injected into the left atrium and T1-weighted images were acquired with every heart beat. Signal intensity measured from the images in regions of the LAD and left circumflex (LCx) perfusion beds was plotted against time to generate signal intensity versus time curves (SI time curve). Various flow indices were derived according to the indicator dilution theory, and compared with and without volume correction due to vasodilation to the myocardial blood flow (MBF) calculated from radiolabeled microspheres. Correlation of the MR and MBF data demonstrated that different transmural and regional myocardial perfusion levels can be easily visualized in the perfusion images and accurately monitored by the SI time curves. Detection of the impairment of myocardial perfusion improved significantly after administration of DIP. The inverse mean transit time calculated from the SI time curve was found to yield a linear correlation to absolute MBF derived from the microsphere data. These results suggest that with intracardiac injections of exogenous contrast agent, myocardial perfusion can be assessed parametrically with first pass contrast enhanced ultrafast MRI.

Animals↗

PubMed1993

Evaluation of left ventricular inflow and volume by MR.

Considerable progress has been achieved during the past few years in the evaluation of intracardial blood flow by MR. Similar to ultrasound Doppler, it is possible now to registrate parameters of left ventricular diastolic filling as E/A ratio, velocity time integral of A- to E-wave (A(area)/E(area)), or isovolumetric relaxation time index. A total of 24 patients (7 women, 17 men, aged 24-69 yr) were examined, 5 of whom suffered from a hypertensive heart disease, 5 from a coronary heart disease, and 7 from mitral valve stenosis of various degree; 7 showed normal findings. E/A-ratio, A(area)/E(area), as well as isovolumetric relaxation time (IVRT) were evaluated by two different examiners on the same day by MR and ultrasound-Doppler, showing correlation factors of .89 for E/A ratio, .67 for A(area)/E(area), and .76 for IVRT in comparing both techniques. Additionally, to test the potential for making left ventricular function diagnoses from MR, time-volume curves for normal cases and patients with hypertrophic and dilated cardiomyopathy were elaborated by a computer-assisted 3D imaging technique. This technique showed good concordance with the results from cardiac catheterization or radionuclide ventriculography.

Adult↗

PubMed1993

[Quantitative evaluation of aortic valve insufficiency in magnetic resonance tomography].

Flow-encoded magnetic resonance (MR) sequences allow the quantitative evaluation of blood flow in any plane of the heart and vessels. For the first time, ejection and regurgitation volumes of the left ventricle in the ascending aorta can be measured noninvasively. Thus, the regurgitation fraction as a reliable measure of aortic valve insufficiency can be determined. The quantitative evaluation of aortic valve insufficiency was done by MR in comparison to ultrasound-Doppler and, in some cases, in comparison to heart catheterization. A good correlation of grading aortic valve insufficiency by the new MR-technique in comparison to clinical graduation is shown. The development of a new noninvasive standard for quantification of aortic valve insufficiency seems possible.

Adult↗

PubMed1991

[Magnetic resonance rheography in comparison to Doppler ultrasonography in the assessment of mitral valve stenosis].

Ultrasound-Doppler-technique and heart catheterization today are used routinely for the evaluation and graduation of mitral valve stenosis. A new magnetic resonance-technique of intracardial blood-flow registration now allows the grading of mitral valve stenosis. Good reliability and practicability of the demonstrated method in comparison with the ultrasound-Doppler-technique is shown. Future development of an alternative, completing magnetic-resonance method for the evaluation of valvular heart disease and shunt diagnosis is expected.

Adult↗

PubMed1990

[Monitoring of an acute compartment syndrome of unusual etiology using MRI (magnetic resonance tomography) and MRS (magnetic resonance spectroscopy)].

The authors report on an acute compartment syndrome occurring symmetrically in the extensors of both forearms. The etiology of this unique compartment syndrome, not previously described, could be attributed to the inhalation of a propane-butane gas mixture, low in oxygen, while sleeping, in combination with external compression of both forearms, due to the patient's head lying on both forearms while sleeping. Ischemic damage to muscles was precisely located using non-invasive MRI (Magnetic Resonance Imaging). The extent of cellular damage due to ischemia after fasciotomy and healing by secondary intention was quantitatively assessed using non-invasive 31P-MRS (Phosphorus Magnetic Resonance Spectroscopy). The results correlate with the clinical and histological findings and indicate a bioenergetic regeneration of the ischemic skeletal muscle's cells.

Adult↗