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ABSTRACT: Background
It is common to treat patients with metastatic disease from gastrointestinal neuroendocrine (NE) tumors with surgical reduction to prolong survival. This can be combined with hepatic arterial embolization (HAE) and medical treatment to reduce hormonal symptoms. Today there are no rapid and reliable methods to evaluate the efficacy of HAE in the treatment of neuroendocrine liver metastasis.PurposeTo investigate metabolic changes in hepatic metastases of NE tumors following HAE, and to establish if there are any early spectral patterns that might indicate therapeutic efficacy based on in vivo (31)P MRS data.Material and Methods
Volume selective (31)P MRS was used to study 11 patients with disseminated NE tumors with regional lymph nodes and bilobar liver metastases. Measurements were performed before and 1 and 3 days after HAE.ResultsNon-responders had significantly higher PME/Pi and αNTP/ΣNTP ratios than the responders before HAE (P < 0.05). Three days after HAE, non-responders still had significantly higher αNTP/ΣNTP than the responders did (P < 0.05). We also observed trends for increased PME ratios 3 days after HAE, decreased ATP-levels, and liberated Pi in responders.Conclusion
This (31)P-MRS study showed significant differences in PME/Pi and αNTP/ΣP ratios between responders and non-responders on the day before HAE, which is an interesting finding that may reflect intrinsic properties of the tumor tissue. We also observed trends for cell membrane renewal and increased energy consumption in responders after HAE. These results demonstrate potentials for (31)P-MRS to predict individual responsiveness prior to HAE.
Acta Radiologica 10/2012; · 1.37 Impact Factor
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ABSTRACT: Animal models are frequently used to assess new treatment methods in cancer research. MRI offers a non-invasive in vivo monitoring of tumour tissue and thus allows longitudinal measurements of treatment effects, without the need for large cohorts of animals. Tumour size is an important biomarker of the disease development, but to our knowledge, MRI based size measurements have not yet been verified for small tumours (10-2-10-1 g). The aim of this study was to assess the accuracy of MRI based tumour size measurements of small tumours on mice.
2D and 3D T2-weighted RARE images of tumour bearing mice were acquired in vivo using a 7 T dedicated animal MR system. For the 3D images the acquired image resolution was varied. The images were exported to a PC workstation where the tumour mass was determined assuming a density of 1 g/cm3, using an in-house developed tool for segmentation and delineation. The resulting data were compared to the weight of the resected tumours after sacrifice of the animal using regression analysis.
Strong correlations were demonstrated between MRI- and necropsy determined masses. In general, 3D acquisition was not a prerequisite for high accuracy. However, it was slightly more accurate than 2D when small (<0.2 g) tumours were assessed for inter- and intraobserver variation. In 3D images, the voxel sizes could be increased from 1603 μm3 to 2403 μm3 without affecting the results significantly, thus reducing acquisition time substantially.
2D MRI was sufficient for accurate tumour size measurement, except for small tumours (<0.2 g) where 3D acquisition was necessary to reduce interobserver variation. Acquisition times between 15 and 50 minutes, depending on tumour size, were sufficient for accurate tumour volume measurement. Hence, it is possible to include further MR investigations of the tumour, such as tissue perfusion, diffusion or metabolic composition in the same MR session.
BMC Medical Imaging 05/2012; 12:12. · 1.09 Impact Factor
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ABSTRACT: It is well known that the quality of a quantitative31P MRS measurement relies largely on the performance of the volume selection method, and that image selected in vivo spectroscopy
(ISIS) suffers from contaminating signal caused mostly by Tl smearing. However, these signal errors and their magnitude are
seldom addressed in clinical studies. The aim of this study was therefore to investigate the magnitude of signal errors in31P MRS when using ISIS. The results from the measurements with a homogeneous head phantom are as follows: at low TR/T1 ratios
the contamination increases rapidly, especially for small (< 27 cm3) VOI sizes; at TR/T1 = 1, the signal from a 27 cm3 VOI was 20% too high, and from an 8 cm3 VOI 150% too high. The signal obtained from different VOI positions varied between 80 and 127%. The signal varied linearly
with the31P concentration in the object. However, a too high signal was obtained when the concentration was lower in the region of interest
(inner container) than in the rest of the phantom. The agreement between the simulations and measurements shows that the results
of this study are generally applicable to the measurement geometry and the ISIS experiment order rather than being specific
for the MR system studied. The errors obtained both experimentally and in computer simulations are too large to be ignored
in clinical studies using the ISIS pulse sequence.
MAGMA Magnetic Resonance Materials in Physics Biology and Medicine 04/2012; 14(1):30-38. · 1.88 Impact Factor
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ABSTRACT: Magnetic resonance diffusion tensor imaging (MR-DTI) is used increasingly to detect diffuse axonal injury (DAI) after traumatic brain injury (TBI).
The primary objective was to investigate the changes in the diffusion properties of the corpus callosum in the acute phase and 6 months after TBI and to examine the correlation between DTI parameters and clinical outcome.
Longitudinal prospective study.
MR-DTI was performed in eight patients with suspected DAI within 11 days and at 6 months post-injury. Six controls were also examined. Fractional anisotropy (FA), trace and parallel and perpendicular diffusivity of the corpus callosum were analysed. The main outcome was the extended Glasgow Outcome Scale score, assessed at 6 months.
A significant reduction in FA in the corpus callosum was seen in the acute phase in patients compared with the healthy controls. There was no significant change in the parallel or perpendicular eigenvalues or trace. At 6 months, a significant reduction in FA and a significant increase in trace and perpendicular eigenvalues were noticed compared with controls.
The diffusion properties of the corpus callosum correlated with clinical outcome in this longitudinal investigation.
Brain Injury 01/2011; 25(4):370-8. · 1.36 Impact Factor
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ABSTRACT: High quality, artifact free, ¹H MRS require a homogeneous magnetic field over the volume of interest (VOI) and an effective global water suppression (WS). However, the shim coils act globally and, hence, affect the resonance frequency over the entire object, making the frequency selective WS spatially selective. Unsuppressed water signal may cause spurious echo artifacts. Aim: Study and visualise the effect localised shimming has on WS.
A water suppression imaging (WSI) scan for visualising regions unaffected by the WS was designed and applied in vivo for two different VOI localisations, at two field strengths. Two shim optimisation methods, and first and second order shims were compared. In addition, shim settings for six VOI localisations were retrospectively investigated.
The WSI-scan effectively visualised the spatial extent of the WS. The coverage decreased when the shim was optimised on a smaller VOI. Second order shims accentuated the problem, resulting, on average, in a WS coverage of only 35% of the head volume.
Localised shimming can result in large regions of unsuppressed water, which can lead to spurious echo artifacts in the spectrum. To help overcome these problems globally optimised shims can be used during WS.
MAGMA Magnetic Resonance Materials in Physics Biology and Medicine 01/2011; 24(2):97-107. · 1.88 Impact Factor
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ABSTRACT: The concentration of N-acetylaspartate (NAA) in hippocampus, as measured with magnetic resonance spectroscopy (MRS), and the ratio of NAA/(choline (Cho) + creatine (Cr)) are valuable tools in the lateralization of temporal lobe epilepsy (TLE). MRS of hippocampus is also increasingly used to study certain psychiatric and degenerative diseases. However, the reliability of such measurements of hippocampus has been questioned.
To re-evaluate MRS imaging data from prior control subjects with regard to variation of metabolite concentrations in hippocampus from anterior to posterior and the partial volume (R)contribution to the measurements from adjacent tissue.
Twelve healthy subjects, mean age 33 years, were studied with MRS imaging. The measurement volume was angled along the temporal horns and metabolite concentration images were reconstructed at the MR system. Regions of interest (ROIs) in the anterior, medial, and posterior parts of both hippocampi were evaluated. Signal normalization to the total MRS signal from all ROIs permitted pooling of individual data with different and unknown signal scaling. One subject was re-examined with a high resolution three-dimensional (3D) volume of the brain for evaluation of partial volumes in the MRS examination.
Overall, there were significantly lower concentrations of NAA in the anterior parts, and of (Cho+Cr) in the posterior parts, while the NAA/(Cho+Cr) ratio in the posterior parts of the mesial temporal lobes was significantly higher. Hippocampus accounted for one-half, one-third, and one-quarter of the anterior, middle, and posterior ROIs, respectively. The NAA/(Cho+Cr) ratio thus showed a reverse relationship to the relative volume of hippocampal tissue within the ROI.
Metabolite concentrations in the mesial temporal lobe obtained with MRS imaging represent the mean value of hippocampus and a considerable amount of adjacent tissue. To assess the hippocampus alone, an actual voxel well below 1 cm(3) and a sub-centimeter slice thickness are required.
Acta Radiologica 04/2010; 51(3):351-9. · 1.37 Impact Factor
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ABSTRACT: Various treatment options are available for articular cartilage lesions, but controversy exists regarding the quality of the repair tissue and the durability of the results posttreatment. Noninvasive techniques are needed for the assessment of the repair tissue.
Magnetic resonance imaging (MRI) with delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) can give valuable information regarding the quality and quantity of the repaired cartilage lesion.
Cohort study; Level of evidence, 3.
Thirty-six knees in 31 patients were assessed 9 to 18 years after treatment with autologous chondrocyte implantation (ACI). All patients had isolated lesions. The knees were clinically evaluated with the Knee injury and Osteoarthritis Outcome Score and the dGEMRIC technique. The T1 value was measured for 2 regions of interest (ROIs), 1 in the repair tissue area (ROI 1) and 1 in the surrounding cartilage (ROI 2), giving information of the content of proteoglycans.
The average T1 value in ROI 1 was 467.5 milliseconds and in ROI 2, 495.3 milliseconds, which yielded no significant difference, thus suggesting comparable levels of proteoglycans in the repair tissue and surrounding cartilage. Intralesional osteophytes were in 64% of the lesions, mainly in younger patients with osteochondritis dissecans lesions or a history of subchondral bone surgeries. Medium or large bone marrow edema was found in 14% of the knees and subchondral cysts, in 39%. There was no correlation between the KOOS and any MRI findings.
Magnetic resonance imaging with dGEMRIC gives valuable information for the macroscopic appearance and micro-molecular quality of the repair tissue after ACI. Nine to 18 years posttreatment, the quality of the repair tissue is similar to the surrounding normal cartilage, although intralesional osteophytes, subchondral cysts, and bone marrow edema were common. The defect area is restored in most patients. However, there was no correlation between the dGEMRIC values and the KOOS outcomes.
The American journal of sports medicine 02/2010; 38(5):943-9. · 3.61 Impact Factor
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Göran Starck, Maria Ljungberg,
Marie Nilsson,
Lars Jönsson,
Stefan Lundberg,
Tord Ivarsson,
Susanne Ribbelin,
Sven Ekholm,
Arvid Carlsson,
Eva Forssell-Aronsson,
Maria L Carlsson
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ABSTRACT: 1H magnetic resonance spectroscopy (1H MRS) studies exploring brain metabolites, especially glutamine + glutamate (Glx), in obsessive compulsive disorder (OCD) are of vital interest for trying to understand more about the pathophysiology of OCD. Therefore, we conducted the present 1H MRS study with the aims of (1) comparing MRS metabolites in a group of adult patients with OCD and a group of healthy controls, and (2) examining the relationship between MRS metabolite concentrations and symptom severity in the patient group. Three brain regions were studied, the right caudate nucleus, the anterior gyrus cinguli and the occipital cortex bilaterally. Since multivariate analysis is a highly useful tool for extraction of 1H MRS data, we applied principal component analysis (PCA) and partial least square projection to latent structures (PLS) to the MRS data. PLS disclosed a strong relationship between several of the metabolites and OCD symptom severity, as measured with Yale-Brown obsessive-compulsive scale (YBOCS): the YBOCS score was found to be positively correlated to caudate creatine, Glx, glutamate, and choline compounds as well as occipital cortex myoinositol, and negatively correlated to occipital cortex Glx. The negative correlation between occipital cortex Glx and YBOCS was the most impressive. PCA did not reveal any tendency for a separation between the patients with OCD and controls with respect to MRS metabolites. The results are discussed in relation to corticostriatothalamocortical feedback and previous observations of poor visuospatial ability in OCD.
Acta Neurovegetativa 08/2008; 115(7):1051-62. · 2.73 Impact Factor
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ABSTRACT: Temporal lobe resection for epilepsy involves a risk of damaging the anterior part of the optic radiation, Meyer's loop, causing a contralateral upper quadrant visual field defect. This study aims to assess the intersubject variability in the course of Meyer's loop in vivo by diffusion tensor imaging and tractography.
Seven healthy volunteers and two patients with previous temporal lobe resection were recruited. Diffusion tensor imaging and tractography were used to visualize the optic radiation. The distances from the anterior edge of Meyer's loop to landmarks in the temporal lobe were calculated.
In the healthy subjects, the mean distance between the most anterior part of Meyer's loop and the temporal pole was 44 mm (range 34-51 mm). Meyer's loop did not reach the tip of the temporal horn in any subject. A disruption in Meyer's loop could be demonstrated in the patient with quadrantanopia after temporal lobe resection.
Meyer's loop has a considerable variability in its anterior extent. Tractography may be a useful method to visualize Meyer's loop, and assess the risk of a visual field defect, prior to temporal lobe resection.
Epilepsy Research 11/2007; 77(1):11-6. · 2.29 Impact Factor
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ABSTRACT: Susceptibility differences are common causes for artifacts in magnetic resonance (MR); therefore, it is important to choose phantom materials in a way that these artifacts are kept at a minimum. In this study, a previously proposed MR imaging (MRI) method [Beuf O, Briguet A, Lissac M, Davis R. Magnetic resonance imaging for the determination of magnetic susceptibility of materials. J Magn Reson 1996; Series B(112):111-118] was improved to facilitate sensitive in-house measurements of different phantom materials so that such artifacts can more easily be minimized. Using standard MRI protocols and distilled water as reference, we measured magnetic volume susceptibility differences with a clinical MR system. Two imaging techniques, echo planar imaging (EPI) and spin echo, were compared using liquid samples whose susceptibilities were verified by MR spectroscopy. The EPI sequence has a very narrow bandwidth in the phase-encoding direction, which gives an increased sensitivity to magnetic field inhomogeneities. All MRI measurements were evaluated in two ways: (1) manual image analysis and (2) model fitting. The narrow bandwidth of the EPI made it possible to detect very small susceptibility differences (equivalent susceptibility difference, Deltachi(e)> or =0.02 ppm), and even plastics could be measured. Model fitting yielded high accuracy and high sensitivity and was less sensitive to other image artifacts as compared with manual image analysis.
Magnetic Resonance Imaging 11/2006; 24(9):1179-85. · 1.99 Impact Factor
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ABSTRACT: It is well known that the quality of a quantitative 31P MRS measurement relies largely on the performance of the volume selection method, and that image selected in vivo spectroscopy (ISIS) suffers from contaminating signal caused mostly by T1 smearing. However, these signal errors and their magnitude are seldom addressed in clinical studies. The aim of this study was therefore to investigate the magnitude of signal errors in 31P MRS when using ISIS. The results from the measurements with a homogeneous head phantom are as follows: at low TR/T1 ratios the contamination increases rapidly, especially for small (<27 cm3) VOI sizes; at TR/T1=1, the signal from a 27 cm3 VOI was 20% too high, and from an 8 cm3 VOI 150% too high. The signal obtained from different VOI positions varied between 80 and 127%. The signal varied linearly with the 31P concentration in the object. However, a too high signal was obtained when the concentration was lower in the region of interest (inner container) than in the rest of the phantom. The agreement between the simulations and measurements shows that the results of this study are generally applicable to the measurement geometry and the ISIS experiment order rather than being specific for the MR system studied. The errors obtained both experimentally and in computer simulations are too large to be ignored in clinical studies using the ISIS pulse sequence.
MAGMA Magnetic Resonance Materials in Physics Biology and Medicine 03/2002; 14(1):30-8. · 1.88 Impact Factor
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ABSTRACT: Image selected in vivo spectroscopy (ISIS) is a volume selection method often used for in vivo 31P MRS, since it is suitable for measurements of substances with short T2. However, ISIS can suffer from significant signal contributions caused by T1 smearing from regions outside the VOI. A computer model was developed to simulate this contamination. The simulation results for the ISIS experiment order implemented in our MR system (ISIS-0) were in agreement with results obtained from phantom measurements. A new extended ISIS experiment order (E-ISIS) was developed, consisting of four “optimal” ISIS experiment orders (ISIS-1 to ISIS-4) performed consecutively with dummy ISIS experiments in between. The simulation results show that contamination due to T1 smearing is, effectively, eliminated with E-ISIS and is significantly lower than for ISIS-0 and ISIS-1. E-ISIS offers increased accuracy for quantitative and qualitative determination of substances studied using in vivo MRS. Hence, E-ISIS can be valuable for both clinical and research applications. Magn Reson Med 44:546–555, 2000. © 2000 Wiley-Liss, Inc.
Magnetic Resonance in Medicine 10/2000; 44(4):546 - 555. · 2.96 Impact Factor
