| 1. |
- Ahmad, Tashfeen, et al.
(författare)
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Peripheral quantitative computed tomography for the detection of diabetic osteopathy: a study in the Goto-Kakizaki rat.
- 2003
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Ingår i: Investigative radiology. - 0020-9996. ; 38:3, s. 171-6
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Tidskriftsartikel (refereegranskat)abstract
- RATIONALE AND OBJECTIVE: To assess the utility of dual energy x-ray absorptiometry (DEXA) and peripheral quantitative computed tomography (pQCT) in detecting trabecular and cortical bone changes in diabetes as a model of osteopenia. MATERIALS AND METHODS: The tibia from 10 type-2 diabetic Goto-Kakizaki (GK) rats and 10 control Wistar rats were analyzed by DEXA, pQCT, and ash weight determination. RESULTS: DEXA of GK rats showed a significant reduction in mineral content (32%) and density (24%) of the metaphysis, but not of the diaphysis. PQCT disclosed that the reduction of density predominantly pertained to the trabecular bone (reduced by 62%). Periosteal and endosteal circumferences of the diaphyses were increased and cortical thickness was unchanged leading to increased moment of inertia. CONCLUSIONS: This study suggests that in osteopathic conditions, cortical and trabecular bone should be separately examined within specific subregions to obtain relevant information. Loss of metaphyseal trabecular bone seems to be a predominant feature in diabetic rats. Moreover, there is increased moment of inertia in the diaphysis implying increased strength. These diagnostic features of diabetic osteopathy can only be assessed by pQCT. It may prove that similar changes occur in human type-2 diabetes, which could explain the susceptibility to periarticular fracture and Charcot arthropathy.
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| 2. |
- Aksit Ciris, P., et al.
(författare)
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Accelerated Segmented Diffusion-Weighted Prostate Imaging for Higher Resolution, Higher Geometric Fidelity, and Multi-b Perfusion Estimation
- 2019
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Ingår i: Investigative Radiology. - 0020-9996. ; 54:4, s. 238-246
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Tidskriftsartikel (refereegranskat)abstract
- Purpose The aim of this study was to improve the geometric fidelity and spatial resolution of multi-b diffusion-weighted magnetic resonance imaging of the prostate. Materials and Methods An accelerated segmented diffusion imaging sequence was developed and evaluated in 25 patients undergoing multiparametric magnetic resonance imaging examinations of the prostate. A reduced field of view was acquired using an endorectal coil. The number of sampled diffusion weightings, or b-factors, was increased to allow estimation of tissue perfusion based on the intravoxel incoherent motion (IVIM) model. Apparent diffusion coefficients measured with the proposed segmented method were compared with those obtained with conventional single-shot echo-planar imaging (EPI). Results Compared with single-shot EPI, the segmented method resulted in faster acquisition with 2-fold improvement in spatial resolution and a greater than 3-fold improvement in geometric fidelity. Apparent diffusion coefficient values measured with the novel sequence demonstrated excellent agreement with those obtained from the conventional scan (R 2 = 0.91 for b max = 500 s/mm 2 and R 2 = 0.89 for b max = 1400 s/mm 2 ). The IVIM perfusion fraction was 4.0% ± 2.7% for normal peripheral zone, 6.6% ± 3.6% for normal transition zone, and 4.4% ± 2.9% for suspected tumor lesions. Conclusions The proposed accelerated segmented prostate diffusion imaging sequence achieved improvements in both spatial resolution and geometric fidelity, along with concurrent quantification of IVIM perfusion. © 2019 Wolters Kluwer Health, Inc. All rights reserved.
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| 3. |
- 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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| 6. |
- Bjerner, Tomas, et al.
(författare)
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High in-plane resolution T2-weighted magnetic resonance imaging of acute myocardial ischemia in pigs using the intravascular contrast agent NC100150 injection.
- 2004
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Ingår i: Investigative Radiology. - 0020-9996 .- 1536-0210. ; 39:8, s. 470-478
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Tidskriftsartikel (refereegranskat)abstract
- Rationale and Objectives: The intravascular contrast agent NC100150 injection was tested for its ability to demarcate nonperfused myocardium in a porcine model of coronary occlusion. Materials and Methods: A T2-weighted fast spin echo sequence was acquired ex vivo and in vivo during first pass and steady-state circulation of the contrast agent in 2 dosages (2 and 5 mg Fe/kg bw) or saline. Results: Ex vivo, in the high-dose group, the volume of nonperfused myocardium determined from T2-weighted images was 99% of that determined from photographs where perfused myocardium stained with fluorescein. A significantly higher contrast to noise ratio between perfused and nonperfused myocardium was found (both ex and in vivo in steady state) compared with the control group. During first pass, a significant reduction in signal intensity (74 ± 18%) was found in perfused myocardium after contrast injection. Conclusion: NC100150 injection, combined with T2-weighted turbo spin echo imaging, allowed detailed visualization of non-perfused myocardium in the steady state, which corresponded to the area at risk as determined by fluorescein.
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| 7. |
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| 8. |
- Briley-Saebo, Karen C., et al.
(författare)
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Clearance of iron oxide particles in rat liver : effect of hydrated particle size and coating material on liver metabolism
- 2006
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Ingår i: Investigative Radiology. - : Ovid Technologies (Wolters Kluwer Health). - 0020-9996 .- 1536-0210. ; 41:7, s. 560-571
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: We sought to evaluate the effect of the particle size and coating material of various iron oxide preparations on the rate of rat liver clearance. MATERIALS AND METHODS: The following iron oxide formulations were used in this study: dextran-coated ferumoxide (size = 97 nm) and ferumoxtran-10 (size = 21 nm), carboxydextran-coated SHU555A (size = 69 nm) and fractionated SHU555A (size = 12 nm), and oxidized-starch coated materials either unformulated NC100150 (size = 15 nm) or formulated NC100150 injection (size = 12 nm). All formulations were administered to 165 rats at 2 dose levels. Quantitative liver R2* values were obtained during a 63-day time period. The concentration of iron oxide particles in the liver was determined by relaxometry, and these values were used to calculate the particle half-lives in the liver. RESULTS: After the administration of a high dose of iron oxide, the half-life of iron oxide particles in rat liver was 8 days for dextran-coated materials, 10 days for carboxydextran materials, 14 days for unformulated oxidized-starch, and 29 days for formulated oxidized-starch. CONCLUSIONS: The results of the study indicate that materials with similar coating but different sizes exhibited similar rates of liver clearance. It was, therefore, concluded that the coating material significantly influences the rate of iron oxide clearance in rat liver.
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| 9. |
- Bååth, Lars, et al.
(författare)
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Effects of nonionic monomeric and dimeric contrast media on the twitching reaction of the rat. Importance of osmolality and electrolyte content
- 1994
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Ingår i: Investigative Radiology. - 0020-9996. ; 29:11, s. 985-989
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Tidskriftsartikel (refereegranskat)abstract
- RATIONALE AND OBJECTIVES. The authors established a rat model of the twitching reaction to contrast media in striated muscle and investigated the influence of nonionic contrast medium on the twitching reaction regarding the nonionic dimer iodixanol compared with the monomer iohexol and the dimer iotrolan. The authors also studied the influences from the electrolyte additions of iodixanol. METHODS. The interval from start of contrast medium injection to start of head movement was compared for iohexol (140 and 350 mg iodine/mL), iodixanol (150 and 320 mg iodine/mL), and iotrolan (300 mg iodine/mL). Comparison was made with mannitol and mannitol containing the same electrolyte concentrations as iodixanol (150 and 320 mg iodine/mL). RESULTS. No differences in latency period were found between iohexol 140 mg iodine/mL (isotonic) and 350 mg iodine/mL (880 mOsm/kg). Iodixanol caused a lesser effect on the twitching reaction than the iohexol solutions and iotrolan. When the electrolytes of iodixanol were added to mannitol (300 mOsm/kg), there was a later onset of the twitching reaction than with electrolyte-free mannitol. CONCLUSIONS. Differences in latency period caused by a change in osmolality were not found. The interval for a twitching reaction was longer with iodixanol than with iohexol, iotrolan, and iso-osmolar mannitol. The weak effect of the iodixanol solution was probably partially caused by the electrolyte content.
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| 10. |
- Bååth, Lars, et al.
(författare)
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Sodium-calcium balance in nonionic contrast media. Effects on the risk of ventricular fibrillation in the isolated rabbit heart
- 1993
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Ingår i: Investigative Radiology. - 0020-9996. ; 28:3, s. 223-227
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Tidskriftsartikel (refereegranskat)abstract
- RATIONALE AND OBJECTIVES. During coronary arteriography the blood is replaced for a short period of time with a contrast medium (CM) solution. The CM may cause a risk of arrhythmias and ventricular fibrillation (VF). Previous investigations have shown that the addition of small amounts of sodium (10-30 mmol/L) to nonionic CM may decrease the risk of VF from these media. Calcium addition to nonionic CM may reduce a negative inotropic effect. In the current investigation, the changed risk of VF from nonionic CM with 19 to 30 mmol/L NaCl was studied when the media also contained calcium or calcium and magnesium. METHODS. An isolated rabbit heart model was used. The risk of arrhythmias and VF from the nonionic monomer iohexol and the nonionic dimer iodixanol containing 19 to 30 mmol/L NaCl with 0 to 2.5 mmol/L calcium as CaCl2 was studied. In the series with iodixanol, 0 to 0.95 mmol/L MgCl2 also was added to the solutions with sodium and calcium, but the role of magnesium was not especially evaluated in the investigation. RESULTS. Nonionic CM with small amounts of NaCl (19-30 mmol/L), without calcium or with calcium at the level of 0.05 to 0.3 mmol/L, caused the lowest risk of VF. When relatively higher additions of calcium reached the physiologic concentration of 2.5 mmol/L, the CM caused a greater risk of arrhythmias and VF. CONCLUSIONS. When calcium is added to a nonionic CM, the concentration of calcium must be balanced against the NaCl concentration to minimize the risk of VF. Excessive calcium concentration will increase the risk of VF.
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