| ObjectiveTo explore the establishment methods of iron modle which can complete MRI quantitative determination; To study the iron distribution in Organs of Iron overload animal.Materials and Methods1,Preparation of iron modleMaking of simple iron water mold of different iron concentrations:Modle 1, Different iron concentrations of small multi-tube banding model:Injecting 50～48.5 ml distilled water in Number 1～16 50ml tubes respectively, and the difference of water amount in tubes in turn decreasing 0.1ml. Then increasingly injecting 0～1.5ml iron dextran for iron 150mg/ml in turn, and the difference of water amount in adjadjacent tubes is 0.1ml, and divided into 4 layers and placed and fixed increasingly; Modle 2, Different iron concentrations of big multi-tube banding model:Injecting 300～298.9ml distilled water in Number 1～12 300ml tubes respectively, and the difference of water amount in tubes in turn decreasing 0.1ml. Then increasingly injecting 0～1.1 ml iron dextran in turn, and the difference of water amount in adjadjacent tubes is 0.1ml, and divided into 3 layers and placed and fixed increasingly; Modle 3, Different iron concentrations of single small tube model:1.5L plastic bottle containing 1.45L distilled water, injected lml of iron dextran after each MRI scan for 35 times; Modle 4, Different iron concentrations of single big tube model:5L plastic bottle containing 4.3L distilled water, injected 10ml of iron dextran after each MRI scan for 70 times.Making of different concentrations of iron model:Modle 5, Modle 3-Body banding model:Banding Modle 3 with right rib area of normal human; Modle 6, Modle 3-Muscle specimens banding model:Banding Modle 3 with 0.5kg pork specimens; Modle 7, Modle 3-Pure waterm bag-Muscle specimens banding model:Iron water mold and pork specimens as Modle 6, banded with 1000ml iron water bag arround them; Modle 8, Modle 4-Pure waterm bag-Muscle specimens banding model:Banded Modle 4 with 3500ml iron water bag and 0.5kg pork specimens as Modle 7; Modle 9, Modle 4-Muscle specimens-Animal fat cortex banding model:Just changeing the pure water bags of Modle 8 as fresh pig skin, and others are the same as Modle 8.2,iron overload animal modle20 adult male New Zealand white rabbits as the experimental group, one same species rabbit as a normal control group. Deep intramuscular injected iron dextran for iron 150mg/ml with the dose of 15mg/kg weekly in the experimental group, alternate the injection position right to left hind leg. Injected a total of 15 weeks. Before the iron dextran injection,MRI inspection was made to all rabbits, quantitative analysis of normal rabbit liver/muscle signal intensity ratio and T2 value of the liver. Every time one week after the injection of iron dextran to review the MRI,and the next day one or two rabbits were killed randomly, and getting some tissue of liver, spleen, heart, kidney, myocardium, lung, testosterone and lymph node to pathological diagnosis, and the remaining liver tissue were dried for the measurement of LIC by atomic spectrophotometer. Rabbit of control group were killed after the first MRI examination, Excise the tissue of multi-organ for pathological examination. 3,MRI examination equipment and sequencesMRI examination equipment and sequences are the same in the tests of iron modle and iron overload animal modle。Magnetic resonance imaging studies were performed using a 3.0 T Philips system (Achieva 3.0T X-series). Scan parameters:(1) Transverse GRE sequences for signal intensity ratio were acquired with TR of 48ms, TE of 2.5ms, flip angle of 60°, sLICe thickness of 4mm, gap of 3mm, scanning four sLICes, completed scan within one breath. (2) T2 value measurement with a multiple spin-echo (SE) pulse sequence:8-echo axial scan for mild iron deposition were acquired with TR of 2000ms, TE of 8,16,24,32,40,48,56 and 64 ms, sLICe thickness of 4mm, scanning one sLICe, take time of about 8 minutes; 4-echo axial scan for severe iron deposition in the were acquired with TR of 2000ms, TE of 6,12,18 and 24 ms, sLICe thickness of 4mm, scanning one sLICe, take time of about 5 or 7 minutes.Results1,MRI features of the iron modelThe image quality of Modle 1 and Modle 2 is poor, that having heterogeneous signals and much MRI artifacts, and MRI could not complete measure; The image quality of Modle 3 and Modle 4 is GREat, that having intensity signals and rarely MRI artifacts, but only to be measure the value of T2; The signals of Modle 5 are intensity, and having rarely MRI artifacts, but to be measure iron water mold / demic body muscle signal intensity ratio, which was not completely out of the body; The signals of Modle 6 are intensity, and having rarely MRI artifacts, but MRI stop scan as the concentration uppers to certain extent。The image of Modle 8 has much MRI artifacts in the middle of iron water mold or relating to the border area of iron water mold and pure water mold, so Modle 8 cannot complete measure; The signals of Modle 7 and Modle 9 are intensity, and having rarely MRI artifacts, and they can complete GRE scanning for iron water mold / muscle signal intensity ratio and multi-echo scanning for the T2 value of iron water mold。2,iron distribution and MRI features of iron overload animal organsIron overload of liver and spleen:liver and spleen of normal rabbits had no iron deposition particle。After inject iron one time, small part sinusoids existed small number of particles, and LIC and signal of GRE image were narmal, but liver / muscle signal intensity ratio and T2 value were lower than normals, at the same time there were abundant iron particles in spleen。After inject iron twice time, sinusoids and some liver cells existed small number of particles, LIC was higher than normals, and signal of GRE image, liver / muscle signal intensity ratio and T2 value were lower than normals, there were more iron particles than it used to in spleen, and in which the quantity amount of iron particles were larger than in liver。After that, With increase injections, liver iron deposition particles gradual increased from part of sinusoids with small number of particles to all sinusoids and liver cells with abundant particles, and LIC showed an increasing trend, and signal of GRE image, liver / muscle signal intensity ratio and T2 value showed decreased trends。But, after the first injection, there were abundant iron particles in spleen, and in which the quantity amount of iron particles were GREat increased than ever, but after the fourth injection, with the increase of injections, the increase rate is diminishing。In early Heart,kidney,lung,intestine,testis,,lymph node are without iron deposition before the thired injection, only after the thired injection of individual rabbits to see a small amount of iron particles. Because these animal model organs for use is too small, and image of MRI is not fine, or the limit of MRI coil for the examined organs, so these organs can not be examined。Conclusion1,The iron modle which were made up of iron water mold,animal specimens and pure water mold( or animal fat cortex)can complete quantitative determination of iron water mold / muscle signal intensity ratio and the T2 value of iron water mold。2,The different iron models have different value, and among them, Modle 7 and Modle 9 are the best vitro models in the MRI quantitative determination。3,With the increase of injections, Liver iron deposition in iron overload animal increased gradually, which has obvious regularity, that are related with LIC, signal of GRE image and MRI determinational value, and regularities of the other organs are not obviously。Other iron overload organs can not be examined, because these organs are too small or examine technologies are limited.liver is the best organ in MRI iron quantitative analysis。...
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