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1.
PAPER
Mr imaging of avascular femoral head necrosis: pre- and postoperative studies (1993)
Springer
ISSN: 1352-8661
Keywords avascular femoral head necrosis-gd-dtpa-mr tomography
Source: Springer Online Journal Archives 1860-2000
Notes: Abstract Forty-six patients with suspected avascular necrosis of the femoral head were examined by T2- and T1-weighted sequences before and after intravenous infusion of Gd-DTPA. Both sides were involved in 12 cases. The classification was done according to Ficat [1]. In early stages and in postoperative studies a correlation of signal intensity increase after infusion of Gd-DTPA and clinical symptoms was found. Contrast enhancement of the plain low signal intensity area or of the implanted graft on T1-weighted images was assumed vascularized or vital components in seven cases of Ficat I and in 13 postoperative studies. Contrawise, in seven patients with severe postoperative symptoms we found no contrast enhancement indicating avascular regions.
Type of Medium: 1
2.
PAPER
31P magnetic resonance spectroscopy of the liver in an infant with galactosaemia (1993)
Springer
ISSN: 1352-8661
Keywords spectroscopy ; galactosaemia ; liver ; infant ; galactose 1-phosphate
Source: Springer Online Journal Archives 1860-2000
Notes: Abstract Sequential studies of the liver of an infant with galactosaemia were made by phosphorus magnetic resonance spectroscopy (31P MRS). A peak attributable to galactose 1-phosphate (gal 1-P) was seen in early liver spectra. This peak diminished during dietary therapy in the early months of life, corresponding to a falling level of gal 1-P in red blood cells.
Type of Medium: 1
3.
PAPER
How to perform automated curve fitting toin vivo 31P magnetic resonance spectroscopic data (1993)
Springer
ISSN: 1352-8661
Keywords nuclear magnetic resonance spectroscopy ; phosphorus ; brain ; curve fitting ; NMR1™
Source: Springer Online Journal Archives 1860-2000
Notes: Abstract A procedure is presented for the computerized automated curve fitting ofin vivo 31P NMR data. This procedure was implemented in the form of three C shell scripts (Appendix) which automatically execute commands from the commercial software program, NMR1™. The accuracy and limitations of curve fitting was tested using simulated data designed to representin vivo 31P NMR spectra obtained from brain. For isolated peaks, the predicted areas for 140 test spectra were in good agreement with the noise free or ‘true’ values, with variations on the order of that expected for the calculated S/N of the simulated peaks. However, when the S/N was less than 2:1, predicted areas were systemically overestimated; this error was traced to a bias for linewidth overestimates. For peaks that overlap, a second systematic error was noted in predicted areas for adjacent peaks, where one peak area was overestimated and the other was underestimated. Furthermore, these systematic errors show partial inverse co-linearity with each other, increasing in proportion to the extent of peak overlap. The curve fitting procedure and tests described here provide guidelines and cautions to investigators who endeavour to use computerized procedures for the analysis ofin vivo NMR spectroscopic data using NMR1 or other software programs.
Type of Medium: 1
4.
PAPER
31P-NMR spectroscopy of human blood and serum: first results from volunteers and patients with congestive heart failure, diabetes mellitus and hyperlipidaemia (1993)
Springer
ISSN: 1352-8661
Keywords congestive heart failure ; diabetes mellitus ; hyperlipidaemia ; 31P NMR spectroscopy ; blood ; serum
Source: Springer Online Journal Archives 1860-2000
Notes: Abstract 31P-containing metabolites in human blood, serum and erythrocytes were measured or calculated. Phosphodiesters were found in serum, but not in erythrocytes. 2,3-diphosphoglycerate and 2,3-diphosphoglycerate/ATP ratios were increased in patients with congestive heart failure (2,3-diphosphoglycerate by 13% in mild to moderate, 31% in severe congestive heart failure, 2,3-diphosphoglycerate/ATP ratio by 9% in mild to moderate, 38% in severe congestive heart failure); phosphodiesters were increased in diabetes mellitus (by 26%) and even more so in hyperlipidaemia (by 57%). Changes of blood31P compounds with disease states may have diagnostic potential and should be recognized for correction of organ spectra.
Type of Medium: 1
5.
PAPER
Nmr contrast enhancement of brain tumours: comparison of the blood brain barrier tracer GdDTPA and the tumour-selective contrast agent MnTPPS (1993)
Springer
ISSN: 1352-8661
Keywords tumour delineation ; gddtpa ; mntpps ; blood brain barrier ; tumour-selective nmr contrast agent
Source: Springer Online Journal Archives 1860-2000
Notes: Abstract Contrast enhancement of two different NMR contrast agents, GdDTPA and MnTPPS, was compared. Sequential recording ofT 1-weighted images at 50s intervals allowed the observation of the temporal and spatial evolution of the contrast effect in rats with glioma implanted into the right brain hemisphere. The maximum signal intensity ratio of tumour over contralateral striatum was 1.80±0.10 for GdDTPA and 1.61±0.15 for MnTPPS. The enhancement was maximal 3min after application of GdDTPA and fell rapidly to reach half maximum after 24 min. MnTPPS led to maximum tumour enhancement within 11 min and did not return to control level within the observation period (150 min). In the peritumoural edema, an enhancement effect was absent for MnTPPS, but GdDTPA spread out from the tumour resulting in a delayed but strong enhancement outside the tumour. Thus, GdDTPA, as a blood-brain-barrier tracer, led only to a transient contrast enhancement between tumour and surrounding tissue and no unambiguous demarcation of the tumour against peritumoural edema. Application of MnTPPS resulted in a long-lasting strong tumour enhancement and reliable delineation from peritumoural edema.
Type of Medium: 1
6.
PAPER
Complete elimination of the hepatobiliary mr contrast agent Gd-EOB-DTPA in hepatic dysfunction: An experimental study using transport-deficient, mutant rats (1993)
Springer
ISSN: 1352-8661
Keywords liver ; mr contrast agent ; gadolinium ; contrast agent ; elimination ; transport systems
Source: Springer Online Journal Archives 1860-2000
Notes: Abstract Mutant Wistar rats (TR− rats) are characterized by a defect in the canalicular transport system for organic anions in the hepatocytes. Anionic hepatobiliary contrast agents for X-ray and MR imaging usually depend on this transport system for biliary secretion. The current study investigated in rats whether Gd-EOB-DTPA, a hepatocyte-directed MR contrast agent, can be completely eliminated in the absence of biliary excretion, and whether urinary elimination may compensate for the hepatic dysfunction. In TR/t- rats elimination of Gd-EOB-DTPA almost completely depended on renal excretion: following intravenous administration of 25µmol kg−1 Gd-EOB-DTPA only 2.4±0.4% of the injected dose underwent biliary excretion. Nevertheless only 2% of a 10-fold higher dose (250µmolkg−1 Gd-EOB-DTPA) was still detected in the body 24 hours p.a., and less than 0.5% 7 days p.a. (no statistically significant differences as compared to values in control rats). In TR− rats, renal and liver signal intensities on T1-weighted MR images returned to baseline within 24 hours following administration of 25µmol kg−1 Gd-EOB-DTPA. In control rats, return to baseline values was observed already 6 hours after injection of the contrast agent. In conclusion, the hepatobiliary MR contrast agent Gd-EOB-DTPA is effectively and completely cleared from the body even in the virtual absence of biliary excretion. The urinary elimination pathway is able to fully compensate for the deficient hepatic transport system.
Type of Medium: 1
7.
PAPER
Simultaneous preparation of inversion recovery T1 and chemical shift selective contrast using snapshot-FLASH-MRI (1993)
Springer
ISSN: 1352-8661
Keywords MR imaging ; fast imaging ; FLASH ; snapshot FLASH ; T1 mapping ; chemical shift selection ; T1 contrast ; quantitative MRI
Source: Springer Online Journal Archives 1860-2000
Notes: Abstract A new technique based on an inversion recovery (IR) snapshot FLASH MRI sequence is presented, which shows the possibility of combining T1 contrast and chemical-shift selectivity on the same images. The introduction of a CHESS preparation allows qualitative visualization of the T1 recovery of separate chemical species that may arise simultaneously within a given tissue. This kind of preparation also leads to a quantitative determination of T1 times of fat and water, even if both components are present in one image voxel. With this method, the inversion recovery behaviour of just one chemical compound can be visualized in a single experiment lasting a few seconds and quantitatively measured in a multishot experiment.
Type of Medium: 1
8.
PAPER
Investigation of metabolic myopathies by P-31 MRS using a standardized rest-exercise-recovery protocol: a survey of 800 explorations (1993)
Springer
ISSN: 1352-8661
Keywords P-31 MRS ; muscle bioenergetics ; metabolic myopathies ; diagnosis ; therapeutic follow-up
Source: Springer Online Journal Archives 1860-2000
Notes: Abstract A standardized P-31 magnetic resonance spectroscopy (MRS) protocol for the exploration of muscle metabolism by P-31 MRS in trained and untrained subjects as well as in patients with intolerance to exercise has been developed to meet the specific requirements of a clinical environment. This protocol is based on a short-term intense exercise which is very informative and well accepted by volunteers and patients. Invariant metabolic parameters have been established to characterize the normal metabolic response to the protocol. As a matter of fact, the comparative analysis of normal and diseased muscle remains a major requirement to further define metabolic events surrounding muscle contraction and the metabolic anomalies underlying diseases. Deviations from normality can be directly interpreted in terms of specific pathologies in some favourable cases. In most cases, P-31 MRS provides valuable information which has to be processed in conjunction with traditional invasive biochemical, electrophysiological and histoenzymological tests. For malignant and exertional hyperthermias, P-31 MRS constitutes a diagnostic tool with 100% sensitivity, as compared to contracture tests. P-31 MRS has proved particularly useful in the therapeutic follow-up of palliative therapies (coenzyme Q treatment of mitochondriopathies) and in family investigations. It is now an accepted diagnostic tool in the array of tests which are used to characterize muscle disorders in clinical routine. This procedure is already approved for reimbursement in the public hospital system in Marseille, France.
Type of Medium: 1
9.
PAPER
ISSN: 1352-8661
Keywords kidney ; angiomyolipoma ; mri
Source: Springer Online Journal Archives 1860-2000
Notes: Abstract The MR appearance of 13 renal angiomyolipomas in 11 patients were reviewed. The fatty tissue in angiomyolipomas which demonstrated hyperintensity on Tl-weighted imaging was considered to be a key point for diagnosis with MRI. Renal angiomyolipomas were classified into three types according to the proportion of fatty tissue in tumours. Fatty tissue comprises more than 80% of the volume of an angiomyolipoma in type I, 20–80% in type II and less than 20% in type III tumours. It was easy to diagnose types I and II renal angiomyolipomas with MRI, but it was quite difficult to differentiate type III renal angiomyolipomas from other solitary occupying lesions such as renal cell carcinoma. Other MR characteristics of renal angiomyolipomas are summarized and are thought to have diagnostic uses.
Type of Medium: 1
10.
PAPER
The Bremen vacuum cap — a valuable positioning device for use in MRI (1993)
Springer
ISSN: 1352-8661
Keywords brain ; MR studies ; spine ; vacuum cap ; movement artifacts ; image quality ; positioning device
Source: Springer Online Journal Archives 1860-2000
Notes: Abstract Simple styrofoam-filled vacuum positioning devices have been developed. The amount of styrofoam pellets within vacuum caps can be changed easily in order to fit their volume to the size of different MR-resonators and to patients head size. It was found that they may successfully be used in order to avoid movement artifacts in MRI-studies of the head, the cervical spine and the spine of adults and children, without any reduction of S/N. These devices may also be used in computed tomography and digital subtraction angiography because they do not produce any beam hardening artifacts. We conclude, that the use of vacuum positioning devices improve image quality and shortens the overall MR measurement time by reduction of movement artifacts.
Type of Medium: 1