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- Åkeson, Per
(author)
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Gadodiamide injection for Enhancement of MRI in the CNS. Applications, dose, field and time dependence.
- 1996
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Doctoral thesis (other academic/artistic)abstract
- Aims of the study The aims of this study using Gadodiamide injection were to investigate: · Whether Gadodiamide injection was comparable to Gd-DTPA for the enhancement of CNS lesions. · The contrast effect at different field strengths. · The effective time-window for the enhancement of blood-brain barrier damage. · The relations between the concentration of contrast agent and enhancement in phantoms, and to correlate the results to doses given to patients. · The use of a higher dose in two important clinical problems; the detection of metastases in the brain, and the evaluation of patients with failed back surgery syndrome (patients with recurrent pain after surgery for lumbar disc herniation). Results and conclusions · Gadodiamide injection was comparable to Gd-DTPA with regard to both safety and diagnostic efficacy in the CNS. · The contrast effect of Gadolinium contrast agents is higher at 1.5 T than at 0.3 T both in phantoms and patients with a maximum ratio (signal lesion / signal grey matter) more than 50% higher at 1.5T. · To achieve high contrast effect, heavily T1-weighted images are also important at both field strengths, as prolonging the repetition time from 400 ms to 600 ms reduced the ratio by 15-45% depending on concentration. · The effective time-window for imaging of blood-brain barrier damage is between 2-5 and 25-30 minutes after injection and several scans can be performed without loss of enhancement. · To provide maximum detectability of blood-brain-barrier-damage in patients with brain lesions, higher doses of Gd contrast media should be useful, as the doses used clinically today do not utilize the maximum contrast effect, either at high or low field strength. However, higher doses are more important at low field strengths because the contrast effect is lower than at high field strengths. · High-dose (0.3 mmol/kg b.w.) contrast-enhanced T1-weighted spin-echo MRI with Gadodiamide injection allowed detection of significantly (p<<0.01) more and smaller metastases than standard-dose (0.1 mmol/kg b.w.) MRI at 0.3 T. High-dose contrast-enhanced MRI with Gadodiamide injection is an efficient way to improve the detection of brain metastases. This should also be true for blood-brain barrier disruptions of other causes. · High-dose (0.3 mmol/kg b.w.) contrast-enhanced T1-weighted spin-echo MRI at 0.3T did not increase the diagnostic information in patients with recurrent pain after surgery for lumbar disc herniation compared to standard-dose (0.1 mmol/kg b.w.) MRI. The high dose images were considered more informative than the standard dose images when compared in pairs but gave no additional or different diagnostic information when evaluated separately.
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| 2. |
- Åkeson, Per, et al.
(author)
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Brain lesion contrast in MR imaging. Dependence on field strength and concentration of gadodiamide injection in patients and phantoms
- 1997
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In: Acta Radiologica. - 1600-0455. ; 38:1, s. 14-18
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Journal article (peer-reviewed)abstract
- PURPOSE: To compare the contrast effects of gadodiamide injection at 0.3 and at 1.5 T, at different concentrations in phantoms, and to correlate the results to clinical doses used for examining brain lesions. MATERIAL AND METHODS: Gel phantoms with T1 and T2 corresponding to brain gray matter were doped with different concentrations of gadodiamide injection and examined with T1-weighted sequences. Two different sets of phantoms were used, one for 0.3 T and one for 1.5 T. To express contrast, a quotient (RATIOphantom) between signals in each tube with gadodiamide injection and in the one without it was calculated. A corresponding quotient (RATIOpatient) between signals in brain metastases and in gray matter was calculated in 16 patients examined at 0.3 T (0.1 and 0.3 mmol Gd/kg b.w.) and in 5 patients examined at 1.5 T (0.1 mmol Gd/kg b.w.). RESULTS: Maximum RATIOphantom and RATIOpatient were more than 50% higher at 1.5 T than at 0.3 T at equal concentrations using heavily T1-weighted sequences. The use of SE TR/TE 600/30 instead of 400/25 reduced the contrast effect 15-45% depending on concentration. Comparing RATIOpatient to RATIOphantom suggests that the maximum T1 effect of Gd contrast media occurs at higher doses than in current clinical use, as at 0.1 mmol/kg b.w. we achieved 38% (0.3 T) and 56% (1.5 T) of the maximum phantoms. At 0.3 mmol/kg b.w. we achieved 63% (0.3 T) of the theoretical maximum. CONCLUSION: The contrast effect of Gd contrast media is higher at 1.5 T than at 0.3 T. Higher doses than presently used might prove useful especially at lower field strengths where the contrast effect of Gd is less pronounced. Heavy T1-weighting is also important.
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| 3. |
- Åkeson, Per, et al.
(author)
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Brain metastases--comparison of gadodiamide injection-enhanced MR imaging at standard and high dose, contrast-enhanced CT and non-contrast-enhanced MR imaging
- 1995
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In: Acta Radiologica. - 1600-0455. ; 36:3, s. 300-306
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Journal article (peer-reviewed)abstract
- The aim was to compare the abilities of contrast-enhanced CT, non-contrast-enhanced MR imaging and contrast-enhanced MR imaging using standard (0.1 mmol/kg b.w.) and high (0.3 mmol/kg b.w.) doses of Gadodiamide injection to detect brain metastases (i.e. blood-brain barrier damage). Sixteen patients with at least 2 metastases found by CT were evaluated by MR imaging using non-contrast-enhanced spin-echo, T1-weighted, T2-weighted sequences, and contrast-enhanced spin-echo T1-weighted sequences at 2 dose levels. Gadodiamide injection was first given at the dose of 0.1 mmol/kg b.w. After imaging, another 0.2 mmol/kg b.w. was given, yielding a cumulative dose of 0.3 mmol/kg b.w. No contrast media-related adverse events were recorded. The images were evaluated openly by one and blindly by 2 investigators and the number of metastases, size, delineation (open study) and diagnostic certainty (blind study) of each individual metastasis noted. High-dose MR imaging showed significantly more and smaller metastases than any other examination, and gave a higher diagnostic certainty. All high-dose images were superior to those with the standard dose MR imaging when compared blindly in pairs. We conclude that spin-echo MR imaging with a high dose of Gadodiamide injection is an efficient way to improve the detection of brain metastases, in particular of small ones.
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| 4. |
- Åkeson, Per, et al.
(author)
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Contrast-enhanced MRI of the central nervous system: comparison between gadodiamide injection and gadolinium-DTPA
- 1995
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In: Neuroradiology. - 1432-1920. ; 37:3, s. 229-233
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Journal article (peer-reviewed)abstract
- Gadodiamide injection, a new nonionic, MRI contrast medium, was compared with the ionic agent gadolinium (Gd)-DTPA at 0.1 mmol/kg body weight in a double-blind, randomised trial in 60 patients, 30 receiving each substance, with known or suspected lesions of the central nervous system. The patients were closely questioned about adverse events. In the Gadodiamide injection group, four patients reported six adverse advents, three of which were judged to be related to the contrast medium. In the Gd-DTPA group, two patients each reported one adverse event, both of which had an uncertain relation to the contrast medium. All events were mild and no medical treatment was needed. No significant change in neurological findings, blood pressure, pulse rate or blood parameters were noted in any patient. Both contrast media were effective; no difference in overall efficacy or safety was observed.
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| 5. |
- Åkeson, Per, et al.
(author)
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Time-dependency in brain lesion enhancement with gadodiamide injection
- 1997
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In: Acta Radiologica. - 1600-0455. ; 38:1, s. 19-24
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Journal article (peer-reviewed)abstract
- PURPOSE: To determine the effective time window for MR imaging of tumors with blood-brain barrier (BBB) damage after injection of Gd-containing contrast media. MATERIAL AND METHODS: Eleven patients with 15 brain lesions (metastasis, glioma, abscess) were studied with a T1-weighted spin-echo sequence repeated over periods of up to 43 min after contrast injection. A quotient was calculated between the signals in the lesion and in the gray matter, and plotted against time. RESULTS: All lesions reached 70% of the maximum RATIO within 3.5 min. After 25 min 12 out of 15 lesions showed persistent enhancement within 15% of the maximal RATIO. CONCLUSION: The peak enhancement of BBB damage occurs around 3.5 min after injection. The effect does not change during the next 25 min. Scanning should not be started until 2-5 min after injection of the contrast medium, and there is no advantage in waiting longer as no major increase (or decline) of contrast can be expected.
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