1.
Sundgren, P C, et al.
(författare)
MRI and proton spectroscopy in a child with Rasmussen's encephalitis. Case report
1999
Ingår i: Neuroradiology. - : Springer Science and Business Media LLC. - 1432-1920 .- 0028-3940. ; 41:12, s. 935-940
Tidskriftsartikel (refereegranskat) abstract
The greater sensitivity of magnetic resonance spectroscopy (MRS) compared with MRI to brain abnormalities in Rasmussen's encephalitis was demonstrated in a 3-year-old boy. The patient, with symptoms, signs and morphological findings consistent with Rasmussen's encephalitis, was followed with MRI and MRS over 30 months. That metabolic changes can be disclosed by MRS before the development of symptoms or signs was demonstrated as pathological spectra were found not only in the diseased left hemisphere but also in the morphologically normal right hemisphere before any neurological disturbance of that side.
2.
Björkman-Burtscher, Isabella, et al.
(författare)
Aneurysm clip MR artifacts. Titanium versus stainless steel and influence of imaging parameters
1998
Ingår i: Acta Radiologica. - 1600-0455. ; 39:1, s. 70-76
Tidskriftsartikel (refereegranskat) abstract
PURPOSE: The aim of this study was to evaluate the extent to which titanium aneurysm clips could improve the quality of MR imaging compared with stainless steel clips, and to determine whether the clip artifacts could be reduced by controlling certain MR imaging parameters in frequently used pulse sequences. MATERIAL AND METHODS: The metal artifacts induced by 3 aneurysm clips were compared in 3 pulse sequences. The clips were: a Yasargil titanium aneurysm clip FT 752 T; a Yasargil standard aneurysm clip FE 752 K; and, for comparison, a ferromagnetic Scoville aneurysm clip En-58J. The pulse sequences were: spin echo (SE); gradient echo (GE); and fast SE. An evaluation was made of 3 imaging parameters with regard to their influence on the size of the metal artifacts. The parameters were: bandwidth; echo time (TE); and echo-train length. RESULTS: The titanium clip showed artifacts that were about 60% smaller than those from the stainless steel clip. The only parameter that influenced artifact size to any major degree was bandwidth in the SE sequences but not in the GE sequences. GE sequences induced larger artifacts than SE sequences and showed larger artifacts with longer TE. CONCLUSION: Titanium aneurysm clips reduced MR artifacts by approximately 60% compared to stainless steel clips. Artifacts were further reduced by using SE-based sequences with a high bandwidth or, if necessary, GE sequences with a low TE.
3.
Björkman-Burtscher, Isabella, et al.
(författare)
In vivo proton MR spectroscopy of untreated and treated brain abscesses
1999
Ingår i: AJNR. - 1936-959X. ; 20:6, s. 1049-1053
Tidskriftsartikel (refereegranskat) abstract
MR spectroscopy was performed in three patients with brain abscesses. In two patients, MR spectroscopy revealed end-products of bacterial breakdown (acetate, succinate, amino acids, lactate) in the abscess cysts. In one of these, the spectrum was reversed to a single lactate peak after treatment. In the third patient, MR spectroscopy was performed only after treatment and showed a single nonspecific lactate peak. MR spectroscopy is a potential tool for noninvasive diagnosis of brain abscess and might be useful for evaluating changes after treatment.
4.
Björkman-Burtscher, Isabella, et al.
(författare)
Proton (1H) MR spectroscopy for routine diagnostic evaluation of brain lesions
1997
Ingår i: Acta Radiologica. - 1600-0455. ; 38:6, s. 953-960
Tidskriftsartikel (refereegranskat) abstract
PURPOSE: To describe the introduction and performance of proton MR spectroscopy (1H-MRS) in the daily routine of a modern standard MR unit. MATERIAL AND METHODS: Over an 8-month period, 52 patients with brain lesions were studied with 1H-MRS, using SE and STEAM sequences for chemical-shift imaging and single-volume spectroscopy. The quality of the spectra was graded from 1 (best) to 3, and the main factors influencing the quality of the spectra were evaluated. RESULTS: Of the measurements: 85% were graded as 1; 12% as 2; and 3% as 3. The main reasons for poor spectral quality were: the unfortunate positioning of the VOI; hemorrhage; and/or postoperative changes within the VOI. Of 40 patients with a final diagnosis: MRS provided an increased confidence in MR diagnosis in 18 cases; MRS contributed significantly to preoperative diagnosis in 3 cases; and the spectra were not specific (n = 10) or were difficult to evaluate (n = 9) owing to reduced quality (grade 2 or 3) in 19 cases. CONCLUSION: MRS of the brain can provide a high percentage of interpretable spectra and frequently can increase confidence in the MR diagnosis of brain lesions in clinical routine.
5.
Björkman-Burtscher, Isabella
(författare)
Proton Magnetic Resonance Spectroscopy in Brain Tumors - Clinical Applications
1999
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
Aims: · to present a test phantom and test method for evaluation of proton magnetic resonance spectroscopy (1H-MRS) single volume localization techniques regarding signal contamination; · to describe the introduction of 1H-MRS in the daily routine of a standard MR-unit; · to evaluate the possibilities offered by 1H-MRS to improve preoperative diagnostic accuracy in patients scheduled for stereotactic biopsy of intracranial mass lesions; · to evaluate the possibilities offered by 1H-MRS to improve diagnostics and therapy control in patients with brain abscesses; · to test the hypothesis that 1H-MRS might be useful for differentiation of brain tumors, based on metabolic changes in tissue across brain lesions or surrounding tissue. Results and conclusions: · The test phantom and test method allow quality assessment with good reproducibility. Contamination values for the tested sequence types and sizes of volume of interest (VOI) differed between 0.7% and 13.8% in one dimension and between 7% and 19.1% in three dimensions. · Of the first 102 MRS measurements performed 85% were of high spectral quality. Main reasons for poor quality were mal-positioning of the VOI, susceptibility problems due to hemorrhage, and post operative changes. · Metabolite ratios of normal tissue differed from those representing stereotactic target points. No significant difference between metabolite ratios representing different histopathologic tumor types could be seen. MRS could improve diagnostic accuracy in differentiation between infiltrating and circumscribed brain lesions based on different spatial distribution of pathologic spectra across the lesion. · MR spectra from abscesses showed resonances, not found in other intracranial pathologies and vanishing under antibiotic treatment, and can therefore be used to differentiate abscesses from other ring-enhancing lesions and might be used for therapy control. · Metabolite ratios representing different components of brain lesions or adjacent tissue differed significantly for the following differential diagnoses: a) high-grade glioma versus metastasis: NAA/Cho and Cr/Cho in contrast-enhancing tissue, and NAA/Cho in tissue adjacent to and at one voxel distance to the lesion; b) meningeoma versus low-grade glioma and metastasis: NAA/Cho in contrast-enhancing tissue; c) low-grade glioma versus metastasis: NAA/Cr in tissue adjacent to the lesion. Our data support the hypothesis that proton MRS can be useful for the reliable differentiation between brain tumors, tending to infiltrate adjacent tissue, and circumscribed, non-infiltrating brain lesions.
6.
Björkman-Burtscher, Isabella, et al.
(författare)
Quality assessment of localization technique performance in small volume in vivo 1H MR spectroscopy
1999
Ingår i: Magnetic Resonance Imaging. - 1873-5894. ; 17:10, s. 1511-1519
Tidskriftsartikel (refereegranskat) abstract
A new phantom and evaluation method for experimental evaluation of 1H-magnetic resonance spectroscopy single volume localization techniques regarding signal contamination (C), defined as the part of the signal originating outside the volume of interest, is presented. The quality assessment method is based on a spherical phantom with an oil/water interface in order to reduce susceptibility effects, and applied for stimulated-echo acquisition method (STEAM) and spin-echo (SE) sequences, echo times of 270, 135, and 10 ms, and cubic volumes of interest (VOI) of 1(3), 1.5(3), 2(3), 2.5(3), and 3(3) cm3. To be able to mimic measurements of the contamination in three dimensions the physical gradients representing the three orthogonal directions for slice selection were shifted in the pulse sequences. Contamination values in one dimension differed between 6.5% and 8.4% in SE sequences, and between 0.7% and 13.8% in STEAM sequences. In STEAM sequences a decrease of C with increasing VOI size was observed while SE sequences showed comparable C values for the different VOI sizes tested. The total contamination in three dimensions were 19% and 18% in SE and STEAM sequences with a TE of 270 ms, and 7% in a STEAM sequence with a TE of 10 ms, respectively. The presented evaluation method is easily applied to the new phantom and showed high reproducibility.
