| 1. |
- Björkman-Burtscher, Isabella, et al.
(författare)
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Proton MR spectroscopy and preoperative diagnostic accuracy: an evaluation of intracranial mass lesions characterized by stereotactic biopsy findings
- 2000
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Ingår i: AJNR. - 1936-959X. ; 21:1, s. 84-93
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND PURPOSE: MR imaging has made it easier to distinguish among the different types of intracranial mass lesions. Nevertheless, it is sometimes impossible to base a diagnosis solely on clinical and neuroradiologic findings, and, in these cases, biopsy must be performed. The purpose of this study was to evaluate the hypothesis that proton MR spectroscopy is able to improve preoperative diagnostic accuracy in cases of intracranial tumors and may therefore obviate stereotactic biopsy. METHODS: Twenty-six patients with intracranial tumors underwent MR imaging, proton MR spectroscopy, and stereotactic biopsy. MR spectroscopic findings were evaluated for the distribution pattern of pathologic spectra (NAA/Cho ratio < 1) across the lesion and neighboring tissue, for signal ratios in different tumor types, and for their potential to improve preoperative diagnostic accuracy. RESULTS: Gliomas and lymphomas showed pathologic spectra outside the area of contrast enhancement while four nonastrocytic circumscribed tumors (meningioma, pineocytoma, metastasis, and germinoma) showed no pathologic spectra outside the region of enhancement. No significant correlation was found between different tumor types and signal ratios. MR spectroscopy improved diagnostic accuracy by differentiating infiltrative from circumscribed tumors; however, diagnostic accuracy was not improved in terms of differentiating the types of infiltrative or circumscribed lesions. CONCLUSION: MR spectroscopy can improve diagnostic accuracy by differentiating circumscribed brain lesions from histologically infiltrating processes, which may be difficult or impossible solely on the basis of clinical or neuroradiologic findings.
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| 2. |
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| 3. |
- Bergqvist, D, et al.
(författare)
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Haverikommission granskade karotiskirurgins komplikationer. Hälften kunde förklaras med misstag eller tveksamma indikationer
- 2000
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Ingår i: Läkartidningen. - 0023-7205. ; 97:14, s. 1673-1676
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Tidskriftsartikel (refereegranskat)abstract
- As carotid endarterectomy is a prophylactic procedure, it would seem particularly important to analyze complications with an aim to avoiding them. All carotid endarterectomies in Sweden are registered, and all serious complications (death and permanent neurological deficit) are analyzed in detail, classified and discussed within the profession. During the period 1994-1996 the frequency was 4.3 percent (technical causes in 17 percent, contraindications in 8 percent and dubious indications in 21 percent, but correct indication and surgery in 54 percent). Thus, even when conditions are optimal there is a certain price to pay for the prevention of ischemic stroke.
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| 4. |
- Nyman, Ulf, et al.
(författare)
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Primary stenting in infrarenal aortic occlusive disease
- 2000
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Ingår i: Cardiovascular and Interventional Radiology. - : Springer Science and Business Media LLC. - 1432-086X .- 0174-1551. ; 23:2, s. 97-108
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To evaluate the results of primary stenting in aortic occlusive disease. METHODS: Thirty patients underwent primary stenting of focal concentric (n = 2) and complex aortic stenoses (n = 19), and aortic or aorto-iliac occlusions (n = 9). Sixteen patients underwent endovascular outflow procedures, three of whom also had distal open surgical reconstructions. Median follow-up was 16 months (range 1-60 months). RESULTS: Guidewire crossing of two aorto-biiliac occlusions failed, resulting in a 93% (28/30) technical success. Major complications included one access hematoma, one myocardial infarction, one death (recurrent thromboembolism) in a patient with widespread malignancy, and one fatal hemorrhage during thrombolysis of distal emboli from a recanalized occluded iliac artery. One patient did not improve his symptoms, resulting in a 1-month clinical success of 83% (25/30). Following restenting the 26 stented survivors changed their clinical limb status to +3 (n = 17) and +2 (n = 9). During follow-up one symptomatic aortic restenosis occurred and was successfully restented. CONCLUSIONS: Primary stenting of complex aortic stenoses and short occlusions is an attractive alternative to conventional surgery. Larger studies with longer follow-up and stratification of lesion morphology are warranted to define its role relative to balloon angioplasty. Stenting of aorto-biiliac occlusions is feasible but its role relative to bypass grafting remains to be defined.
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| 5. |
- Wahlgren, N G, et al.
(författare)
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Multidisciplinärt samarbete bakom kvalitetsregister för karotiskirurgi. God täckningsgrad under de första två verksamhetsåren
- 2000
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Ingår i: Läkartidningen. - 0023-7205. ; 97:14, s. 1678-1678
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Tidskriftsartikel (refereegranskat)abstract
- Carotid surgery prevents recurrent stroke in patients with symptomatic tight stenosis of the carotid artery. The Swedish Carotid Surgery Monitoring Registry seeks to promote selection of patients with significant spontaneous risk for recurrent stroke, with an eye toward expediting evaluation and minimizing surgical complications. To this end, professionals at participating hospitals are informed about their own patient selection and surgery risk in comparison with those in the country as a whole and with set targets. We report the results from the first two years, during which it is estimated that more than half of all patients eligible for carotid surgery in Sweden were included in the registry. Although almost all patients had recent onset of relevant neurological symptoms, less than 60% had a documented tight (80-99% occlusion) stenosis. While the final decision to operate a patient was made within 4 weeks of onset of symptoms for only 18% of the patients the first year, this proportion increased to 33% in the following year. The total incidence of surgery related stroke, myocardial infarct and death was 7.7%, while the incidence of severe stroke, myocardial infarct and death was 3.0%.
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| 6. |
- Wirestam, Ronnie, et al.
(författare)
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Regional cerebral blood flow distributions in normal volunteers: dynamic susceptibility contrast MRI compared with 99mTc-HMPAO SPECT
- 2000
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Ingår i: Journal of Computer Assisted Tomography. - 1532-3145. ; 24:4, s. 526-530
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Relative regional cerebral blood flow (rCBF) at rest was measured in 44 volunteers using both dynamic susceptibility contrast (DSC) MRI and (99m)Tc-HMPAO SPECT on the same day. METHOD: In MRI, a Gd-DTPA-BMA contrast agent bolus (0.3 mmol/kg body wt) was monitored with a simultaneous dual FLASH pulse sequence (time resolution 1.5 s). MRI-based rCBF images were calculated by singular value decomposition-based deconvolution of the measured tissue concentration-time curve with an arterial input function from a small artery within the imaging slice. In the SPECT investigation, 900 MBq of (99m)Tc-HMPAO was injected intravenously. Relative rCBF in gray matter in the thalamus and in frontal white matter was determined. RESULTS: The ratio of relative rCBF in gray matter to relative rCBF in white matter was 2.21 +/- 0.57 using MRI and 2.24 +/- 0.54 using SPECT (mean +/- SD). CONCLUSION: Relative rCBF maps from DSC MRI and (99m)Tc-HMPAO SPECT showed good agreement, and the MRI-based rCBF ratio correlated with the corresponding SPECT-based ratio (r = 0.79, p < 0.0000006).
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| 7. |
- Amundsen, T, et al.
(författare)
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A closed-chest pulmonary artery occlusion/reperfusion model in the pig: detection of experimental pulmonary embolism with MR angiography and perfusion MR imaging
- 2000
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Ingår i: Investigative Radiology. - 0020-9996. ; 35:5, s. 295-303
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Tidskriftsartikel (refereegranskat)abstract
- RATIONALE AND OBJECTIVES: To establish a pig model suitable for imitating pulmonary emboli to facilitate research in the diagnosis of pulmonary embolism. METHODS: Thirteen animals were anesthetized, mechanically ventilated, and subjected to pulmonary artery catheterization initiated from the right external jugular vein. With the use of a Swan-Ganz catheter, repetitive occlusion/reperfusion maneuvers were done at different locations of the pulmonary arterial tree. Conventional pulmonary angiography, MR angiography, and perfusion MR imaging were performed. RESULTS: The model remained hemodynamically stable throughout the 13 experiments, without any significant difference between the blood pressure measurements at the start and at the end of the right-heart and pulmonary artery catheterizations. In each of the nine animal experiments that investigated MR imaging, four of four using perfusion MR imaging (proximal and distal occlusions) and five of five using MR angiography (larger pulmonary artery occlusions), all repeated pulmonary artery occlusions were successfully performed (reproducibility of 100%). CONCLUSIONS: The closed-chest pulmonary artery occlusion/reperfusion model in the pig allowed repetitive, controlled imitations of pulmonary emboli at different levels of the pulmonary artery in the same experiment. MR angiography and perfusion MR imaging were adequate to detect the pulmonary artery occlusions and the nonperfused lung regions, respectively. The model may be a helpful tool for future research in this field.
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| 8. |
- Areberg, Johan
(författare)
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Studies of radioactive cisplatin (191Pt) for tumour imaging and therapy
- 2000
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A radioactive variant of the cytostatic agent cis-dichlorodiammineplatinum(II), cisplatin, was synthesised from 191PtCl4. The 191Pt-cisplatin was found to be a sterile product of high radionuclide, radiochemical and chemical purity. The pharmacokinetics of platinum in tumour tissue and organs at risk of fourteen patients undergoing treatment with cisplatin were studied by exchanging a small fraction of the prescribed amount of cisplatin with 191Pt-cisplatin. The uptake and retention of platinum were investigated by gamma camera measurements up to ten days after infusion of 191Pt-cisplatin. Highest concentration of platinum was found in the liver, on average 5.7 ± 0.5 mikrog/g normalised to a given amount of 180 mg cisplatin. Corresponding value for the kidneys was 1.9 ± 0.3 mikrog/g. Uptake of platinum in tumours was visualised in five patients with an average maximum concentration of 4.9 ± 1.0 mikrog/g normalised to a given amount of 180 mg cisplatin. The data from the pharmacokinetic study was used together with data from the literature to estimate the absorbed dose and effective dose to patients receiving radioactive cisplatin. The effective doses were calculated to be 0.10 ± 0.02 mSv/MBq, 0.17 ± 0.04 mSv/MBq and 0.23± 0.05 mSv/MBq for 191Pt-, 193mPt-, and 195mPt-cisplatin respectively. The combined effect of the radio- and chemotoxicity from 191Pt-cisplatin was investigated both in vitro and in vivo. A cervical cancer cell line was incubated with cisplatin or 191Pt-cisplatin with various concentrations and specific activities. It was shown that the surviving fraction was smaller for cells treated with 191Pt-cisplatin than for cells treated with the same concentration of non-radioactive cisplatin. The surviving fraction decreased with increasing specific activity. Isobologram technique showed that the radio- and chemotoxicity interacted in a supra-additive (synergistic) manner. In an in vivo model, nude mice with xenografted tumours were given physiological saline (controls), cisplatin or 191Pt-cisplatin. The growth was significantly more retarded for the tumours on the mice given 191Pt-cisplatin compared with the tumours on the other mice. No significant change in general toxic effect, manifested as weight change or mortality, could be detected between the groups of mice given cisplatin and 191Pt-cisplatin respectively. 191Pt-cisplatin was shown to be a radiopharmaceutical suitable for both tumour imaging and therapy. There is potential for an increased use of radioactive cisplatin in the future.
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| 9. |
- Arlig, A, et al.
(författare)
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Attenuation correction in quantitative SPECT of cerebral blood flow: a Monte Carlo study
- 2000
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Ingår i: Physics in Medicine and Biology. - : IOP Publishing. - 1361-6560 .- 0031-9155. ; 45:12, s. 3847-3859
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Tidskriftsartikel (refereegranskat)abstract
- Monte Carlo simulation has been used to produce projections from a voxel-based brain phantom, simulating a 99mTc-HMPAO single photon emission computed tomography (SPECT) brain investigation. For comparison, projections free from the effects of attenuation and scattering were also simulated, giving ideal transaxial images after reconstruction. Three methods of attenuation correction were studied: (a) a pre-processing method, (b) a post-processing uniform method and (c) a post-processing non-uniform method using a density map. The accuracy of these methods was estimated by comparison of the reconstructed images with the ideal images using the normalized mean square error, NMSE, and quantitative values of the regional cerebral blood flow, rCBF. A minimum NMSE was achieved for the effective linear attenuation coefficient mu(eff) = 0.07 (0.09) cm(-1) for the uniform(pre) method, the effective mass attenuation coefficient mu(eff)/rho = 0.08 (0.10) cm2 g(-1) for the uniform(post) method and mu(eff)/rho = 0.12 (0.13) cm2 g(-1) for the non-uniform(post) method. Values in parentheses represent the case of dual-window scatter correction. The non-uniform(post) method performed better, as measured by the NMSE, both with and without scatter correction. Furthermore, the non-uniform(post) method gave, on average, more accurate rCBF values. Although the difference in rCBF accuracy was small between the various methods, the same method should be used for patient studies as for the reference material.
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