In vivo measurements of the T1 relaxation processes in the bone marrow in patients with myelodysplastic syndrome. A magnetic resonance imaging study.

Nine patients with myelodysplastic syndrome (MDS) were examined with magnetic resonance imaging and in vivo T1 relaxation time measurements of the vertebral bone marrow in a 1.5 tesla whole body scanner. Two patients underwent transformation to acute myeloid leukemia and were evaluated at follow-up examinations.

Neuronal pH regulation: constant normal intracellular pH is maintained in brain during low extracellular pH induced by acetazolamide--31P NMR study.

The intracellular pH in the brain was studied in six healthy volunteers before and immediately after the administration of 2 g of acetazolamide. Phosphorus-31 nuclear magnetic resonance spectroscopy by a 1.5 tesla whole-body scanner was used.

In vivo evaluation of femoral blood flow measured with magnetic resonance.

Quantitative measurements of blood flow based on magnetic resonance imaging (MRI) using conventional multiple spin echo sequences were evaluated in vivo in healthy young volunteers. Blood flow was measured using MRI in the femoral vein. The initial slope of the multiple spin echo decay curve, corrected for the T2 decay of non-flowing blood was used to calculate the blood flow.

In vivo measurements of T1 relaxation times of 31P-metabolites in human skeletal muscle.

The T1 relaxation times were estimated for 31P-metabolites in human skeletal muscle. Five healthy volunteers were examined in a 1.5 Tesla wholebody imaging system using an inversion recovery pulse sequence.

Chemical shift selective magnetic resonance imaging of the optic nerve in patients with acute optic neuritis.

Optic neuritis is often the first manifestation of multiple sclerosis (MS). Sixteen patients with acute optic neuritis and one patient with benign intracranial hypertension (BIH) were investigated by magnetic resonance imaging, using a chemical shift selective double spin echo sequence. In 3 of the 16 patients, abnormalities were seen.

In vivo measurement of intracellular pH in human brain during different tensions of carbon dioxide in arterial blood. A 31P-NMR study.

The effect of changes in carbon dioxide tension in arterial blood upon intracellular pH in brain tissue was studied in seven healthy volunteers, aged 22-45 years. The pH changes were monitored by use of 31P nuclear magnetic resonance spectroscopy, performed on a whole-body 1.5 Tesla Siemens imaging system.

Ataxic hemiparesis: three different locations of lesions studied by MRI.

We report three cases of ataxic hemiparesis, studied by MRI. The lesions were all contralateral and located in three different sites: the posterior limb of the internal capsule, the midpons, and the red nucleus. None of the CTs demonstrated the lesions.

Evaluation of biexponential relaxation processes by magnetic resonance imaging. A phantom study.

Despite the complexity of biologic tissues, a monoexponential behaviour is usually assumed when estimating relaxation processes in vivo by magnetic resonance imaging (MRI). This study was designed to evaluate the potential of biexponential decomposition of T1 and T2 relaxation curves obtained at 1.5 tesla (T).

In vivo measurements of relaxation process in the human liver by MRI. The role of respiratory gating/triggering.

In vivo estimation of relaxation processes in the liver by magnetic resonance imaging (MRI) may be helpful for characterization of various pathological conditions in the liver. However, such measurements may be significantly hampered by movement of the liver with the respiration. The effect of synchronization of data acquisition to the respiratory cycle on measured T1- and T2-relaxation curves was studied in normal subjects, patients with diffuse liver disease, and patients with focal liver pathology.

Muscle capillary permeability for [14C]inulin and [51Cr]EDTA in human forearm.

Capillary permeability of [14C]inulin and [51Cr]EDTA was examined in human forearm in five healthy, subjects by indicator diffusion technique. Injections of, initially [125I]albumin and [14C]inulin, and after 30 min resting, of [125I]albumin and [51Cr]EDTA, were given in a brachial artery. During light exercise of the forearm, blood was sampled in 2-s periods from a deep cubital vein primarily draining muscles.

Maintenance of high-energy brain phosphorous compounds during insulin-induced hypoglycemia in men. 31P nuclear magnetic resonance spectroscopy study.

31P nuclear magnetic resonance (NMR) spectroscopy allows noninvasive studies of cerebral energy-rich phosphorous compounds in humans. In an attempt to characterize the relationship between peripheral blood glucose concentrations and whole-brain phosphate metabolism during insulin-induced hypoglycemia, 31P NMR spectra were obtained before and after intravenous injection of insulin (0.15 IU/kg body wt) in six men.

Evaluation of right ventricular volumes measured by magnetic resonance imaging.

Right ventricular volumes were determined in 12 patients with different levels of right and left ventricular function by magnetic resonance imaging (MRI) using an ECG gated multisection technique in planes perpendicular to the diastolic position of the interventricular septum. Right ventricular stroke volume was calculated as the difference between end-diastolic and end-systolic volume and compared to left ventricular stroke volume and to stroke volume determined simultaneously by a classical indicator dilution technique. There was good agreement between right ventricular stroke volume determined by MRI and by the indicator dilution method and between right and left ventricular stroke volume determined by MRI.

Prolonged bone marrow T1-relaxation in patients with polycythemia vera.

In vitro as well as in vivo studies have shown prolonged T1 relaxation times in patients with acute leukemia. The mechanism behind this finding is not known. In order to evaluate if this was specific for leukemia we examined eight patients with polycythemia vera, representing a condition with a rather benign bone marrow neoplasia.

In vivo determination of T1 and T2 in the brain of patients with severe but stable multiple sclerosis.

In vivo measurements of relaxation processes in multiple sclerosis (MS) lesions by magnetic resonance imaging (MRI) may be important for evaluation of the disease activity in individual MS plaques. To obtain information of presumably chronic plaques, 10 patients with severe, but stable MS were investigated, using a whole-body superconductive MR scanner, operating at 1.5 T.

Comparison of different pulse sequences for in vivo determination of T1 relaxation times in the human brain.

Quantitative in vivo determination of T1 relaxation times by magnetic resonance imaging (MRI) is hampered by several potential sources of error. This study focused on the influence of the radiofrequency pulse sequences applied with special attention to the significance of the repetition time (TR). T1 measurements were performed on the human brain using a whole body MR scanner operating at 1.

Surgical treatment of epilepsy. Clinical aspects in children.

Neurosurgery, mainly temporal lobectomy, has given substantial relief of serious seizure problems in two-thirds of children with intractable epilepsy. Since the prognoses of children with an intractable epilepsy is poor, surgery should be considered. To prevent sequela of a long standing seizure disorder and side effects of antiepileptic medication as well as the development of mirror foci, surgery should be considered at an early age.

Magnetic resonance imaging of the prostate.

Magnetic resonance imaging offers new possibilities in investigation of the prostate gland. Current results of imaging and tissue discrimination in the evaluation of prostatic disease are reviewed. Magnetic resonance imaging may be useful in the staging of carcinoma of the prostate.

Specific problems of children with epilepsy.

In both adults and children, the seizure type and frequency of occurrence largely determine the burden of epilepsy, for the patient and his family. Epilepsy in children can range from the severe to the relatively benign, and it is important to make the correct diagnosis as early as possible. In those under 5 years of age, epilepsy often presents as an age-related syndrome, e.

In vivo magnetic resonance imaging and 31P spectroscopy of large human brain tumours at 1.5 tesla.

31P MR spectroscopy of human brain tumours is one feature of magnetic resonance imaging. Eight patients with large superficial brain tumours and eight healthy volunteers were examined with 31P spectroscopy using an 8 cm surface coil for volume selection. Seven frequencies were resolved in our spectra.

Determination of flow velocities from magnetic resonance multiple spin-echo images. A phantom study.

The purpose of this study was to evaluate a method for the quantification of through-plane flow velocities by magnetic resonance imaging (MRI) from the flow characteristics of conventional multiple spin-echo (MSE) signals. Simulated inflow-outflow-dependent signals, as well as images of a flow phantom were generated and the logarithm of the flow-dependent signal value was plotted against echo time. The normalized slope of the resulting curve was calculated using a least-square fit to simulated and experimental data and was corrected for T2 relaxation effects by subtraction of a slope obtained at zero flow.

First-pass radionuclide determination of cardiac output: an improved gamma camera method.

A technique for noninvasive determination of cardiac output by aid of first-pass radionuclide cardiography is described. After intravenous injection of 10-15 mCi technetium-99m-(99mTc) labeled red blood cells the method requires acquisition of a first passage time-activity curve recorded with a gamma camera over the left ventricle, the background corrected left ventricular count rate recorded after complete mixing of the tracer in the circulation, and determination of the distribution volume of the tracer. The method was applied in 14 patients with heart disease of various origins and evaluated against the conventional tracer dilution technique with arterial sampling of blood activity.

Renal vascular adjustments to partial renal venous obstruction in dog kidney.

Blood flow studies were conducted in neurolept anesthetized dogs to characterize the involvement of renal nerves in ipsilateral renal vasoconstriction seen during acute elevation of renal venous pressure above 30 mm Hg. Renal blood flow was measured electromagnetically. The vasoconstrictor response was almost abolished by acute surgical denervation of the kidney, since renal vascular conductance remained unchanged during renal venous pressure elevation from 30-60 mm Hg.