Iron-oxide-enhanced MR imaging of bone marrow in patients with non-Hodgkin's lymphoma: differentiation between tumor infiltration and hypercellular bone marrow

The aim of this study was to differentiate normal, hypercellular, and neoplastic bone marrow based on its MR enhancement after intravenous administration of superparamagnetic iron oxides in patients with cancer of the hematopoietic system. Eighteen patients with cancer of the hematopoietic system underwent MRI of the spine before and after infusion of ferumoxides ( n=9) and ferumoxtran ( n=9) using T1- and T2-weighted turbo spin-echo (TSE) and short tau inversion recovery sequences (STIR). In all patients diffuse or multifocal bone marrow infiltration was suspected, based on iliac crest biopsy and imaging such as conventional radiographs, MRI, and positron emission tomography. In addition, all patients had a therapy-induced normocellular ( n=7) or hypercellular ( n=11) reconversion of the normal non-neoplastic bone marrow. The MRI data were analyzed by measuring pre- and post-contrast signal intensities (SI) of hematopoietic and neoplastic marrow and by calculating the enhancement as deltaSI(%) data and the tumor-to-bone-marrow contrast as contrast-to-noise ratios (CNR). Changes in bone marrow signal intensity after iron oxide administration were more pronounced on STIR images as compared with T1- and T2-weighted TSE images. The STIR images showed a strong signal decline of normal and hypercellular marrow 45-60 min after iron oxide infusion, but no or only a minor signal decline of neoplastic bone marrow lesions; thus, deltaSI% data were significantly higher in normal and hypercellular reconverted marrow compared with neoplastic bone marrow lesions ( p<0.05). Additionally, the contrast between focal or multifocal neoplastic bone marrow infiltration and normal bone marrow, quantified by CNR data, increased significantly on post-contrast STIR images compared with precontrast images ( p<0.05). Superparamagnetic iron oxides are taken up by normal and hypercellular reconverted bone marrow, but not by neoplastic bone marrow lesions, thereby providing significantly different enhancement patterns on T2-weighted MR images; thus, superparamagnetic iron oxides are useful to differentiate normal and neoplastic bone marrow and to increase the bone marrow-to-tumor contrast.     

Superparamagnetic iron oxide contrast agents: physicochemical characteristics and applications in MR imaging

Superparamagnetic iron oxide MR imaging contrast agents have been the subjects of extensive research over the past decade. The iron oxide particle size of these contrast agents varies widely, and influences their physicochemical and pharmacokinetic properties, and thus clinical application. Superparamagnetic agents enhance both T1 and T2/T2* relaxation. In most situations it is their significant capacity to reduce the T2/T2* relaxation time to be utilized. The T1 relaxivity can be improved (and the T2/T2* effect can be reduced) using small particles and T1-weighted imaging sequences. Large iron oxide particles are used for bowel contrast [AMI-121 (i.e. Lumirem and Gastromark) and OMP (i.e. Abdoscan), mean diameter no less than 300 nm] and liver/spleen imaging [AMI-25 (i.e. Endorem and Feridex IV, diameter 80-150 nm); SHU 555A (i.e. Resovist, mean diameter 60 nm)]. Smaller iron oxide particles are selected for lymph node imaging [AMI-227 (i.e. Sinerem and Combidex, diameter 20-40 nm)], bone marrow imaging (AMI-227), perfusion imaging [NC100150 (i.e. Clariscan, mean diameter 20 nm)] and MR angiography (NC100150). Even smaller monocrystalline iron oxide nanoparticles are under research for receptor-directed MR imaging and magnetically labeled cell probe MR imaging. Iron oxide particles for bowel contrast are coated with insoluble material, and all iron oxide particles for intravenous injection are biodegradable. Superparamagnetic agents open up an important field for research in MR imaging.     

Hepatic MRI with SPIO: detection and characterization of focal liver lesions

A variety of parenterally administered iron oxides have been developed for contrast-enhanced MRI of the liver. Two different classes of iron oxides are currently clinically approved or in phase 3 trials: superparamagnetic iron oxides (SPIO) with a high R2/R1 relaxivity ratio and short blood half-life (AMI-25 and SH U 555 A), and ultrasmall paramagnetic iron oxides (USPIO) with a lower R2/R1 relaxivity ratio and longer blood half-life (AMI-227). All iron oxides significantly increase tumor-to-liver contrast and allow detection of more lesions than unenhanced MRI on T2-weighted images at a field strength of 0.2–1.5 T. Malignant lesions without phagocytic cells exhibit constant signal on T2-weighted accumulation phase images with all three iron oxides. All iron oxides cause a signal decrease of benign lesions with either phagocytic cells or a significant blood pool on T2-weighted accumulation phase images. The signal decrease of benign lesions is proportional to the Kupffer cell activity or tumor vascularity and is useful for lesion characterization. Another enhancement feature for the differentiation of benign from malignant lesions is ring enhancement of malignant lesions (metastases) on T1-weighted enhanced images either during the perfusion phase with SH U 555 A or during the accumulation phase with AMI-227, which is attributed to the blood pool effects of the compounds. Differentiation of lesions and vessels is easier on enhanced images with angiographic effects than on unenhanced images. Iron oxides improve the quality of two-dimensional MR angiography techniques of the portal venous system by decreasing background signal (liver tissue with all iron oxides) and increasing intravascular signal (AMI-227). The use of iron oxides for hepatic MRI provides an alternative to the existing multistep diagnosis with CT, CT portography, MRI and biopsy. Received: 24 September 1997; Revision received: 12 November 1997; Accepted: 14 November 1997     

Enhancement of phase-contrast MR angiography with superparamagnetic iron oxide

The effect of superparamagnetic iron oxide particles (AMI-227) was assessed in three-dimensional (3D) phase-contrast (PC) MR angiography (MRA), with various scanning parameters for rats at 1.5 T. The blood T1 and T2 before and after 20 μmol Fe/kg of AMI-227 injection were measured sequentially at .47 T. The visualization of abdominal aorta, renal artery, inferior vena cava, and portal vein was respectively evaluated before and after AMI-227 injection qualitatively by the four confidence levels and quantitatively by analysis of signal-to-noise ratio (SNR) of vessels. The blood T1 and T2 were sufficiently shortened for at least 1 hour after AMI-227 injection. The visualization of each vessel was improved by AMI-227 at various velocity encoding (VENC) value, suggesting the extended application of PC-MRA in various conditions. The optimal flip angle was increased from 20° to 30° in higher VENC after AMI-227 injection, resulting in higher signal from blood flow. Quantitative analyses showed that the optimal flip angle to achieve the maximum SNR seemed to be 20° in unenhanced images, but the optimal flip angle of the high speed flow was increased by contrast enhancement. The postcontrast PC-MRA provides the increased sensitivity of slow flow components, even with a high VENC gradient. AMI-227 can significantly improve SNR to blood vessels during 3D-PC-MRA with various scanning parameters.     

USPIO (Ferumoxtran-10)-enhanced MRI to visualize reticuloendothelial system cells in neonatal rats: feasibility and biodistribution study

Purpose

To investigate whether USPIO‐enhanced magnetic resonance imaging (MRI) detected reticuloendothelial system (RES) cells in newborn normal rats.

Materials and Methods

Newborn normal rats were imaged in vivo on a 1.5 T MR system, 2–96 hours after intraperitoneal Ferumoxtran‐10 (n = 38) or saline injection (control group, n = 5). Signals from liver, spleen, and vertebral bone marrow were measured (T2‐weighted Turbo Spin Echo) to describe the kinetics of enhancement. The pups were sacrificed and iron concentrations in plasma and peritoneal fluid were measured using atomic absorption spectrometry. Prussian blue‐labeled cells density in liver, spleen, and vertebral bone marrow was assessed.

Results

Significant (P < 0.05) negative enhancement of the liver, spleen, and vertebral bone marrow was noted after Ferumoxtran‐10 injection (2–96 hours for liver and spleen, 4–96 hours for bone marrow). Ferumoxtran‐10 was absorbed from the peritoneum in the first 8 hours postinjection, entering the circulation with a plasma peak (8 hours); then Ferumoxtran‐10 returned over the baseline in plasma (96 hours). Important intracellular iron deposition in liver and spleen was measured postinjection (3–96 hours, P < 0.05). Limited but significant intracellular iron deposition was noted in vertebral bone marrow postinjection (96 hours, P < 0.05), suggesting that Ferumoxtran‐10 selectively labeled RES cells after 96 hours and produced nonspecific labeling at earlier timepoints.

Conclusion

Ferumoxtran‐10‐enhanced MRI visualizes RES cells in vivo in newborn rats. J. Magn. Reson. Imaging 2008;28:1046–1052. © 2008 Wiley‐Liss, Inc.     

Carboxymethyldextran-A2-Gd-DOTA enhancement patterns in the abdomen and pelvis in an animal model

The aim of this study was to assess MR signal enhancement patterns of carboxymethyldextran (CMD)-A2-Gd-DOTA, a new macromolecular contrast agent, in the abdomen and pelvis of New Zealand white rabbits. Nine New Zealand white rabbits underwent MRI before and following injection of 0.05 mmol/kg body weight (bw) CMD-A2-Gd-DOTA (52.1 kDa), using turbo FLASH-, dynamic FLASH 60 degrees-, T1- and T2-weighted spin-echo and turbo spin-echo sequences up to 10 days p.i. Changes in blood and tissue signal intensities (deltaSI) and relaxation rates (deltaR1) were calculated. Differences between pre- and post-contrast MRI data were compared using the Scheffé test. CMD-A2-Gd-DOTA demonstrated significant blood-pool enhancement and significant tissue enhancement on T1-weighted images, whereas no significant signal changes were observed on T2-weighted images (P < 0.05). Kidney parenchyma, pelvis and bladder demonstrated a subsequent enhancement, resembling renal elimination of the majority of the contrast agent. Liver parenchyma demonstrated a slow, delayed decay of the contrast enhancement due to storage and biodegradation of larger subfractions of the contrast agent. All tissue signal intensities were back to baseline 10 days p.i. CMD-A2-Gd-DOTA is a new macromolecular contrast agent with blood-pool effect, significant signal enhancement of abdominal organs and pelvic bone marrow, partial storage in the liver and baseline tissue signal intensities by 10 days p.i.     

Extent and time course of morphological changes of bone marrow induced by granulocyte-colony stimulating factor as assessed by magnetic resonance imaging of healthy blood stem cell donors

The aim of this study was to assess the time course and extent of signal alterations of red bone marrow after short-term stimulation by recombinant human granulocyte-colony stimulating factor (rHuG-CSF) in healthy peripheral blood stem cell donors using magnetic resonance imaging (MRI) at low-field strength. Twelve healthy blood stem cell donors without evidence of bone marrow disorders were prospectively investigated and underwent four MRI studies of their lumbar spine. Sagittal T1- and T2-weighted spin-echo sequences and a gradient-echo (GE) sequence with an echo time for out-of-phase imaging were performed prior to rHuG-CSF application (baseline MRI), on the day of first stem cell harvest (after 70 microg/kg body weight rHuG-CSF, second MRI) followed by two studies 9-18 days (median 14.5 days, third MRI) and 26-48 days (median 39.5 days, fourth MRI) after discontinuation of rHuG-CSF application. Baseline MRI showed normal marrow signal in all patients. The second MRI revealed a decrease of quantified bone marrow signal relative to nucleus pulposus in T1- and T2-weighted images and an increase of relative signal in out-of-phase GE sequences. The greatest changes of relative marrow signal were observed at the third MRI. Compared to baseline MRI, relative marrow signal was diminished by 12% in T1-weighted images and increased by 59% in GE sequences, consistent with a rise in marrow cellularity simulating diffuse marrow disease. At the fourth MRI quantified relative marrow signal returned to baseline levels in all sequences. In healthy individuals rHuG-CSF application leads to significant signal changes of bone marrow in lumbar vertebra that are maximal about 2 weeks after discontinuation of rHuG-CSF application. In patients with underlying marrow disorders who receive hematopoietic growth factors during treatment, these changes should not be confused with disease progression.     

Splenic imaging with ultrasmall superparamagnetic iron oxide ferumoxtran-10 (AMI-7227): preliminary observations

PURPOSE: Ferumoxtran-10 (ultrasmall superparamagnetic iron oxide; Combidex, AMI-7227) is a long-circulating MR contrast agent with reticuloendothelial uptake known to enhance tissue T1 and T2 relaxation rates. The purpose of this study was to assess the effect of ferumoxtran-10-enhanced MRI in evaluating focal splenic lesions. METHOD: Eighteen patients underwent MR evaluation of the spleen. Two of these patients with exophytic normal splenic tissue (splenules) and 13 of these patients with 24 focal splenic lesions (7 cysts, 2 hemangiomas, 7 metastases, 1 infarct, 7 lymphoma) were assessed by T1-weighted gradient echo and T2-weighted fast SE MRI following intravenous administration of ferumoxtran-10 (1.1 mg of Fe/kg). Qualitative analysis involving improved lesion detection and/or characterization, additional information from postcontrast images affecting staging, and patient management was performed. Quantitative measurements of lesion-to-spleen contrast-to-noise ratio were also performed. RESULTS: Additional information was provided by ferumoxtran-10-enhanced images in 15 of 18 patients. In 8 of 15 (53%) patients, improved lesion detection (i.e., number of lesions) was obtained on contrast-enhanced images. Improved lesion visualization (i.e., conspicuity) was noted in 11 of 15 (73%) of patients. In 10 of 15 (67%) patients, postcontrast imaging provided additional information leading to lesion characterization. Staging of disease and patient management were affected in 5 of 15 (33%) and 6 of 15 (40%) patients, respectively. CONCLUSION: Ferumoxtran-10 is a promising contrast agent for the evaluation of focal splenic lesions.     

Ferumoxtran-10-enhanced MR imaging of the bone marrow before and after conditioning therapy in patients with non-Hodgkin lymphomas

To quantify permeability changes of the “blood–bone marrow barrier” (BMB) and to detect malignant bone marrow infiltrations before and after conditioning therapy for subsequent leukapheresis using ferumoxtran-10-enhanced magnetic resonance (MR) imaging. Twenty-two patients with malignant non-Hodgkin lymphomas (NHL), including 9 patients (group A) before and 13 patients (group B) after conditioning therapy, underwent MR of the spine before and after infusion of ferumoxtran-10 (0.045 mmol Fe/kg BW). Pulse sequences comprised dynamic T1-GE and pre- and post-contrast T1-SE and STIR sequences. Dynamic ΔSI-data were correlated with the quantity of mobilized CD34+ cells. In addition, the number of focal bone marrow lesions was compared before and after ferumoxtran-10 administration. Dynamic ΔSI-data were higher in group B than in group A, indicating an increased BMB permeability after conditioning therapy. However, ΔSI-data did not correlate with the quantity of mobilized CD34+ cells. Ferumoxtran-10-enhanced STIR images demonstrated a significant signal decline of the normal, non-neoplastic bone marrow and a significantly increased detection of focal neoplastic lesions compared to pre-contrast images (P<0.05). Ferumoxtran-10 depicted the bone marrow response to conditioning therapy by an increase in BMB-permeability, which, however, did not correlate with the number of mobilized CD34+ cells. Ferumoxtran-10 improved the detection of focal bone marrow lesions significantly (P<0.05).     

Magnetic resonance imaging of hepatic focal lesions: dynamic contrastographic evaluation with gadolinium versus reticulo-endothelial hepato-specific contrast media

PURPOSE: To compare the potentials of AMI-25 (Endoren) to those of Gadolinium with the dynamic contrast-enhanced technique in the differential diagnosis of focal liver lesions. MATERIAL AND METHODS: Forty patients with at least one focal liver lesion diagnosed at US underwent MRI. We used a 1.5 T unit and employed single-shot half-Fourier T2-weighted FSE and spoiled gradient-echo T1-weighted sequences before and after Gadolinium injection. Multiple acquisitions were obtained during the arterial, portal and delayed phases. Twenty-four to 48 hours later T2*-weighted GRE and SPGR/90 degrees sequences were obtained after AMI-25 administration. In the characterization of solid lesions the gold standard was biopsy performed with a shearing needle; for the diagnosis of angiomas and of 11 metastatic lesions we considered follow-up and clinical data as important diagnostic elements. RESULTS: We found 12 hepatocarcinomas, 14 metastases, 4 cases of focal nodular hyperplasia (FNH), 4 adenomas and 6 angiomas. The diagnosis was correct and confirmed by the conventional examination in all cases but 2 adenomatous lesions and 2 angiomas. Precontrast studies showed slight hyperintensity in 2 of 4 cases of FNH, while the other 2 lesions appeared isointense and were therefore detected only on postcontrast images, where there was contrast agent uptake during the arterial phase and rapid washout. We found only one central scar hyperintense on T2- and hypointense on T1-weighted images. After AMI-25 administration all lesions appeared isointense to surrounding parenchyma on T2* GRE sequences. Adenomas were isointense in the precontrast phase and postcontrast 3 of them showed strong Gadolinium uptake and rapid washout. After AMI-25 two of the 4 lesions were hyperintense while the other two were isointense to the parenchyma. Four of 6 angiomas exhibited a typical pattern characterized by signal hyperintensity on T2-weighted sequences and on AMI-25-enhanced T1- and T2-weighted sequences. Two angiomas were supposed to be of malignant nature but histology showed the presence of a strong fibrotic component. Hepatocarcinomas could be detected on precontrast images. After Gadolinium administration 10 lesions appeared hyperintense in the arterial phase and 2 were hypointense. After AMI-25 all lesions exhibited homogeneous signal hyperintensity and appeared slightly bigger than on Gadolinium-enhanced images. The metastases were only partly demonstrated by MRI. Postgadolinium studies showed 13 lesions with hyperintense signal in the portal phase. AMI-25 administration detected 14 lesions that appeared slightly bigger than on Gadolinium-enhanced images. CONCLUSIONS: AMI-25 can help also in characterizing primary lesions with an atypical signal pattern after contrast agent administration thanks to its intrinsic capability of accumulating in benign lesions. However it remains difficult to characterize well differentiated hepatocarcinomas and adenomas. Finally, AMI-25 improves MR capabilities in detecting secondary lesions and possible satellite nodules.     

USPIO-enhanced magnetic resonance imaging for nodal staging in patients with head and neck cancer

PURPOSE: To determine the accuracy of ultrasmall superparamagnetic iron oxide (USPIO)-enhanced magnetic resonance imaging (MRI) for nodal staging in patients with head and neck cancer. MATERIALS AND METHODS: Twenty patients with carcinomas of the upper aerodigestive tract were prospectively enrolled. MRI was performed before and 24-36 hours after intravenous infusion of an USPIO agent, ferumoxtran-10 (Sinerem; Guerbet, France; and Combidex; Advanced Magnetics) at a dose of 2.6 mg Fe/kg using T2-weighted spin-echo and gradient-echo sequences. Surgery was performed the same day or the day after the ferumoxtran-10-enhanced MR examination. Based on MRI, selected nodes were surgically removed and directly correlated with pathology using hematoxylin-eosin (H&E) and Perls stainings. RESULTS: A total of 63 nodes were studied; 36 were nonmetastatic, 25 metastatic, and two inflammatory. Ferumoxtran-10-enhanced MRI allowed diagnosis of 24 metastatic and 30 nonmetastatic nodes, yielding a sensitivity of 96%, a specificity of 78.9%, a positive predictive value of 75%, and a negative predictive value of 96.8%, compared to 64%, 78.9%, 66.6%, and 76.9%, respectively, for nonenhanced MRI. Accuracy of ferumoxtran-10-enhanced MRI was 85.7%. The gradient-echo T2-weighted sequence was the most accurate to detect signal loss in nonmetastatic nodes. CONCLUSION: USPIO-enhanced MRI is useful for nodal staging of patients with head and neck cancers.     

Ultrasmall superparamagnetic iron-oxide-enhanced MR imaging of normal bone marrow in rodents: original research original research

RATIONALE AND OBJECTIVES: The objective is to compare three different ultrasmall superparamagnetic iron oxides (USPIOs) for magnetic resonance (MR) imaging of normal bone marrow in rodents. MATERIALS AND METHODS: Femoral bone marrow in 18 Sprague-Dawley rats was examined by using MR imaging before and up to 2 and 24 hours postinjection (PI) of 200 mumol of Fe/kg of SHU555C (n = 6), ferumoxtran-10 (n = 6), or ferumoxytol (n = 6), using T1-weighted (50 ms/1.7 ms/60 degrees = repetition time [TR]/echo time [TE]/flip angle) and T2*-weighted (100 ms/15 ms/38 degrees = TR/TE/flip angle) three-dimensional spoiled gradient recalled echo sequences. USPIO-induced bone marrow was evaluated qualitatively and quantified as signal-to-noise ratio (SNR) and change in signal intensity (DeltaSI) values. A mixed-effect model was fitted to the SNR and DeltaSI values, and differences among USPIOs were tested for significance by using F tests. RESULTS: At 2 hours PI, all three USPIOs showed marked positive signal enhancement on T1-weighted images and a corresponding marked signal loss on T2*-weighted images. At 24 hours PI, the T1 effect of all three USPIOs disappeared, whereas T2*-weighted images showed persistent signal loss on SHU555C and ferumoxytol-enhanced MR images, but not ferumoxtran-10-enhanced MR images. Corresponding SNR and DeltaSI values on T2*-weighted MR images at 24 hours PI were significantly different from baseline for SHU555C and ferumoxytol, but not ferumoxtran-10. CONCLUSION: All three USPIO contrast agents, ferumoxtran-10, ferumoxytol, and SHU555C, can be applied for MR imaging of bone marrow. Ferumoxtran-10 apparently reveals a different kinetic behavior in bone marrow than ferumoxytol and SHU555C.     

Clinical application of superparamagnetic iron oxide to MR imaging of tissue perfusion in vascular liver tumors

Previous studies of AMI-25, a particulate iron oxide magnetic resonance contrast agent, imaged liver tumors 1 or more hours after injection, in the retention phase after complete clearance of AMI-25 from the circulation. In the present study, imaging was performed in the distribution phase, during the first 12 minutes after injection while contrast agent remain in circulation, and these images were compared with those obtained in the retention phase. Nineteen patients with cancer were studied, including 15 imaged during the distribution phase. T2-weighted distribution phase images demonstrated 90% of the lesions detected by means of T2-weighted retention phase images, showed a 3.5-fold increase in contrast-to-noise ratio over images obtained before administration of AMI-25, and increased diagnostic confidence by reducing signal from small intrahepatic blood vessels. Distribution phase images showed little contrast agent uptake by cancer tissue. Both distribution and retention phase images demonstrated greater contrast agent uptake by hemangiomas than by malignant neoplasms (P less than .01). The use of both distribution phase and retention phase AMI-25-enhanced images offers improved diagnostic accuracy in the detection and characterization of focal liver lesions.     

Comparison of ultrasmall superparamagnetic iron oxide particles and low molecular weight contrast agents to detect rejecting transplanted hearts with magnetic resonance imaging

PURPOSE: This study compared 3 different contrast agents for magnetic resonance imaging (MRI) to determine whether their rate of permeability could discriminate between acutely rejecting and nonrejecting transplanted hearts. MATERIALS AND METHODS: Heterotopic heart transplantation in rats was performed and animals were divided into allogeneic and syngeneic groups. At the sixth postoperative day, MRI was performed with 2 ultrasmall superparamagnetic iron oxide particles of different sizes, unformulated NC 100150 and AMI-227, besides gadodiamide. RESULTS: For unformulated NC100150, the signal intensity between the groups differed at all times (P < 0.0001); for AMI-227, all times but 3 (P < 0.05). With low molecular weight gadolinium chelate, no discrimination between rejecting and nonrejecting groups could be made. CONCLUSION: Acutely rejecting and nonrejecting transplanted hearts can be discriminated from each other using the difference in permeability assessed by blood pool agents and MRI. With first pass of gadolinium chelate no discrimination could be made between rejecting and nonrejecting grafts.     

Chondroblastoma and clear cell chondrosarcoma: radiological and MRI characteristics with histopathological correlation

OBJECTIVE: To analyze and compare the radiological and magnetic resonance imaging (MRI) appearances of chondroblastoma and clear cell chondrosarcoma with histopathological correlation. DESIGN AND PATIENTS: Twelve patients with histologically proven chondroblastoma and of another four patients with clear cell chondrosarcoma were investigated by radiographs and MRI (T1-, T2-weighted sequences, intravenous gadolinium application). Additionally, the clinical and radiologic data of seven cases of clear cell chondrosarcoma without available MRI were considered. The localization, calcification of tumor matrix, periosteal reaction, cortical bone and patterns of bone destruction were analyzed according to the Lodwick radiological grading system (LRGS). The signal intensity on T1- and T2-weighted sequences, characteristics of contrast enhancement, associated bone marrow edema, soft tissue reaction and joint involvement were evaluated. Histopathological specimens were available in all cases. RESULTS: The age of patients with chondroblastoma (range 15-59 years, mean 22.3 years) was lower than that of those with clear cell chondrosarcoma (range 19-61 years, mean 36.6 years), and the lesions were smaller in the chondroblastoma group (range 1-4 cm, mean 2.3 cm) than in patients with clear cell chondrosarcoma (range 3-7.5 cm, mean 5.2 cm). The chondroblastomas were more confined to the epiphysis (10/12) than the clear cell chondrosarcomas. All chondroblastomas and clear cell chondrosarcomas except one were classified as grade 1A or 1B according to the LRGS; one clear cell chondrosarcoma was judged as grade 2. Signal intensity of the tumors on MRI was very heterogeneous in both groups. High signal intensity on T2-weighted MR images in chondroblastoma mostly corresponded to areas with aneurysmal bone cyst components and in clear cell chondrosarcoma to islands of hyaline cartilage. Contrast enhancement occurred in all tumors and tended to be more intense with clear cell chondrosarcoma. Chondroblastoma was more frequently associated with bone marrow edema (11/12), periosteal reaction (10/12), soft tissue reaction (7/12) and synovitis (3/12). CONCLUSION: Chondroblastoma occurs in younger patients, is smaller than clear cell chondrosarcoma and is more confined to the epiphysis. The overlap of signal intensity and contrast enhancement patterns does not allow a reliable differentiation of the two tumors by MRI. Chondroblastomas are typically associated with bone marrow edema, periosteal reaction and soft tissue reaction.     

MRI of degenerative bone marrow lesions in experimental osteoarthritis of canine knee joints

 Objective. The objective of this study was to determine the value of MRI in the detection of degenerative bone marrow abnormalities in an animal osteoarthritis model. Design. In 10 dogs with experimentally induced unilateral osteoarthritis of the knee, MRI was performed using two-dimensional spin-echo (2D-SE) and three-dimensional gradient-echo (3D-GE) imaging. Contrast enhanced T1-weighted 2D-SE sequences were also obtained after injection of gadolinium-DTPA. The results were compared with the gross and histopathologic findings and with radiography. Results. Histopathologic specimens revealed 21 osteosclerotic lesions and 5 intraosseous cysts. On 2D-SE images, 24 of 26 lesions were detected, while 21 of 26 lesions were identified on 2D-GE sequences. Radiography, including conventional tomography, demonstrated 9 of 26 lesions. Regardless of the sequence weighting, all osteosclerotic lesions appeared hypointense on MRI. Signal loss in bone sclerosis resulted primarily from the reduction of intact fat marrow, the increased bone density being of secondary importance. Quantitative signal analysis allowed approximate estimation of the grade of sclerosis. On postcontrast images, sclerotic bone remained hypointense, although significant but non-specific enhancement relative to the normal fat marrow was observed. The extent of contrast enhancement did not correlate with the grade of osteosclerosis. All five cysts were readily diagnosed by MRI. Cysts displayed either central or marginal contrast enhancement within their cavities. Conclusions. MRI provides a sensitive method for the diagnosis of osteoarthritic bone abnormalities, allowing their differentiation from most non-degenerative subarticular lesions.     

正常乳猪骨骺及干骺端骨髓的增强MR成像研究

目的 :探讨正常乳猪骨骺及干骺端骨髓的增强MR表现特征及不同年龄阶段的骨髓转化特征。方法 :8头乳猪 ,分别在出生 2、4、6和 8周的时间对双侧股骨近段及远段进行增强前后T1WIMR扫描 ,分析不同时间骨骺二次骨化中心骨髓和干骺端骨髓增强MR表现特征及增强率的变化 ,并与相应组织学发现进行对照研究。结果 :干骺端骨髓和骨骺二次骨化中心周边骨髓为含有丰富血管的红骨髓 ,增强后呈显著强化 ,且干骺端增强率较骨骺骨髓更高 ,但随年龄增长 ,两者的增强率均逐渐减低。骨干中央和二次骨化中心中央为黄骨髓 ,强化不明显。结论 :Gd DTPA增强在干骺端红骨髓与二次骨化中心周边红骨髓比在骨骺二次骨化中心中央区域黄骨髓强化更明显 ,其强化程度随年龄的增长逐渐减弱。     

MR lymphography with iron oxide compound AMI-227: studies in ferrets with filariasis.

OBJECTIVE. The purpose of this study was to assess the MR lymphographic potential of AMI-227 to reduce the signal intensity of hyperplastic inflammatory lymph nodes by using ferrets with filariasis as the animal model. Both interstitial and IV modes of administration were studied. MATERIALS AND METHODS. Twelve ferrets were infected with the filaria Brugia malayi and six control ferrets were injected with super-paramagnetic iron oxide AMI-227, either interstitially or IV. Signal intensities of the left popliteal lymph node, left hamstring muscle, and left inguinal fat were measured before, 48 hr after, and up to 138 days after contrast injection with the use of both spin-echo and gradient-echo techniques. The signal intensity data were statistically analyzed. The lymph nodes, liver, spleen, and lungs were studied with light and electron microscopy. RESULTS. Forty-eight hours after the interstitial injection of AMI-227, the signal intensities of the ipsilateral popliteal nodes of the infected and control ferrets were significantly reduced (p less than .0005) without significant changes in the signal intensities of the surrounding tissues on both spin-echo and gradient-echo MR images. No nodal signal reduction occurred with the IV route of injection in ferrets. Light microscopy revealed iron to be localized within nodal marginal zones exclusively. Lymphatic trunks were visualized after interstitial injection. Signal reduction persisted to our end point at 138 days. CONCLUSION. AMI-227 shows regional specificity with significant enhancement of nodal structures and demonstrates potential as an interstitial MR lymphographic agent.     

MR多种成像技术在原发性骨质疏松椎体骨折鉴别诊断中的应用

目的 :探讨MR多种成像技术对鉴别原发性骨质疏松椎体骨折与其它原因所致病理性骨折的价值。方法 :对14例原发性骨质疏松椎体压缩骨折和 2 0例转移瘤所致骨折患者行MRI检查 ,成像序列均包括SET1 WI、FSET2 WI、STIR、DWI和增强SET1 WI抑脂序列 ,分析病变椎体在不同MR成像序列上的信号表现 ,计算病变区的强化比率、ADC值和骨髓对比率 ,进行统计学分析。结果 :SET1 WI、FSET2 WI、STIR和增强扫描上病变椎体横形分层样信号、椎体后上角后突及前后径增加、附件信号异常、邻近椎间盘信号增高、局部软组织肿块及椎管内结构受累在两组间发生率差异明显 ,骨质疏松骨折与转移瘤所致骨折的ADC值无显著性差异 (P >0 .0 5 ) ,两者强化比率和骨髓对比率有显著性差异 (P <0 .0 1)。结论 :MR多种成像技术联合应用对原发性骨质疏松椎体骨折与其它原因所致病理性骨折的鉴别可提供很大帮助     

Superparamagnetic iron oxide: Detection of focal liver lesions at high-field-strength MR imaging

AMI-25 was evaluated at 1.5 T as a superparamagnetic iron oxide contrast agent for the liver. Sixteen patients with up to five suspected focal liver lesions were examined with T1-, proton-density—, and T2-weighted spin-echo sequences before and after intravenous administration of AMI-25 (15 μmol/kg iron). The contrast-to-noise ratio (C/N) increased from 1.8 to 3.5 on 600/15 (TR msec/TE msec) images and from 1.7 to 7.9 on 2,500/15 images after AMI-25 administration (P <.01). C/N did not change significantly on 2,500/90 images. Two blinded readers counted the number of lesions visible on unenhanced and contrast-enhanced images, with the 32 sets of images of the 16 patients presented in random order. Both readers identified more lesions on AMI-25–enhanced images, but the difference was not statistically significant (P >.05). Two patients reported minor side effects (flushing, sensation of heat, lower back pain). On the basis of the results obtained in a limited number of patients, the authors conclude that at 1.5 T, AMI-25 does not significantly improve the detection of focal liver lesions on conventional spin-echo images.