Serial MR Imaging of Magnetically Labeled Humen Umbilical Vein Endothelial Cells in Acute Renal Failure Rat Model

PURPOSE: To evaluate the usefulness of in vivo magnetic resonance (MR) imaging for tracking intravenously injected superparamagnetic iron oxide (SPIO)-labeled human umbilical vein endothelial cells (HUVECs) in an acute renal failure (ARF) rat model. MATERIALS AND METHODS: HUVECs were labeled with SPIO and poly-L-lysine (PLL) complex. Relaxation rates at 1.5-T MR, cell viability, and labeling stability were assessed. HUVECs were injected into the tail vein of ARF rats (labeled cells in 10 rats, unlabeled cells in 2 rats). Follow-up serial T2*-weighted gradient-echo MR imaging was performed at 1, 3, 5 and 7 days after injection, and the MR findings were compared with histologic findings. RESULTS: There was an average of 98.4+/-2.4% Prussian blue stain-positive cells after labeling with SPIO-PLL complex. Relaxation rates (R2*) of all cultured HUVECs at day 3 and 5 were not markedly decreased compared with that at day 1. The stability of SPIO in HUVECs was maintained during the proliferation of HUVECs in culture media. In the presence of left unilateral renal artery ischemia, T2*-weighted MR imaging performed 1 day after the intravenous injection of labeled HUVECs revealed a significant signal intensity (SI) loss exclusively in the left renal outer medulla regions, but not in the right kidney. The MR imaging findings at days 3, 5 and 7 after intravenous injection of HUVECs showed a SI loss in the outer medulla regions of the ischemically injured kidney, but the SI progressively recovered with time and the right kidney did not have a significant change in SI in the same period. Upon histologic analysis, the SI loss on MR images was correspondent to the presence of Prussian blue stained cells, primarily in the renal outer medulla. CONCLUSION: MR imaging appears to be useful for in vivo monitoring of intravenously injected SPIO-labeled HUVECs in an ischemically injured rat kidney.

Diffusion-Weighted MR Imaging before and after Contrast Enhancement with Superparamagnetic Iron Oxide for Assessment of Hepatic Metastasis

PURPOSE: The purpose of our study was to validate diffusion-weighted MRI (DWI) before and after superparamagnetic iron oxide (SPIO) injection for assessment of hepatic metastases. MATERIALS AND METHODS: Eighty-six hepatic metastases (size range, 0.3-4.7 cm; mean, 1.5 cm) verified pathologically or by follow-up imaging studies in 22 consecutive patients (17 men and 5 women; 44-83 years; mean age, 60 years) during a 13-month period were enrolled. Hepatic MRI, including DWI (b-factors=50, 400, 800 s/mm2) with breath-holding technique of single-shot spin-echo echo-planar imaging (TR/TE=1000/69 ms, average=2) before and after SPIO administration, were retrospectively reviewed by two independent radiologists with a 5-point scale confidence score for each hepatic lesion on pre-contrast DWI (pre-DWI), SPIO-enhanced DWI (SPIO-DWI), and SPIO-enhanced T2*-weighted imaging (SPIO-T2*wI). RESULTS: For all lesions, SPIO-T2*wI showed significantly higher confidence score in the diagnosis of hepatic metastases than pre-contrast or SPIO-DWI regardless of the size of b-factors (p0.05). Pre-DWI using b-factor=50 sec/mm2 was also comparable with SPIO-T2*wI by observer 1 (p=0.060). CONCLUSION: Pre-DWI has a limited value for the assessment of hepatic metastases, however, the repetition of DWI after SPIO injection using small b-factors could complement SPIO-T2*wI, especially for subcentimeter lesions.

Ferucarbotran-Enhanced Hepatic MRI at 3T Unit: Quantitative and Qualitative Comparison of Fast Breath-hold Imaging Sequences

PURPOSE: To compare the relative values of various fast breath-hold imaging sequences for superparamagnetic iron-oxide (SPIO)-enhanced hepatic MRI for the assessment of solid focal lesions with a 3T MRI unit. MATERIALS AND METHODS: 102 consecutive patients with one or more solid malignant hepatic lesions were evaluated by spoiled gradient echo (GRE) sequences with three different echo times (2.4 msec [GRE_2.4], 5.8 msec [GRE_5.8], and 10 msec [GRE_10]) for T2*-weighted imaging in addition to T2-weighted turbo spin echo (TSE) sequence following intravenous SPIO injection. Image qualities of the hepatic contour, vascular landmarks and artifacts were rated by two independent readers using a four-point scale. For quantitative analysis, contrast-to-noise ratio (CNR) was measured in 170 solid focal lesions larger than 1 cm (107 hepatocellular carcinomas, nine cholangiocarcinomas and 54 metastases). RESULTS: GRE_5.8 showed the highest mean points for hepatic contour, vascular anatomy and imaging artifact presence among all of the subjected sequences (p<0.001) and was comparable (p=0.414) with GRE_10 with regard to lesion conspicuity. The mean CNRs were significantly higher (p<0.001) in the following order: GRE_10 (24.4+/-14.5), GRE_5.8 (14.8+/-9.4), TSE (9.7+/-6.3), and GRE_2.4 (7.9+/-6.4). The mean CNRs of CCCs and metastases were higher than those of HCCs for all imaging sequences (p<0.05). CONCLUSION: Regarding overall performances, GRE using a moderate echo time of 5.8 msec can provide the most reliable data among the various fast breath-hold SPIO-enhanced hepatic MRI sequences at 3T unit despite the lower CNR of GRE_5.8 compared to that of GRE_10.

Ferucarbotran-Enhanced Hepatic MRI at 3T Unit: Quantitative and Qualitative Comparison of Fast Breath-hold Imaging Sequences

PURPOSE: To compare the relative values of various fast breath-hold imaging sequences for superparamagnetic iron-oxide (SPIO)-enhanced hepatic MRI for the assessment of solid focal lesions with a 3T MRI unit. MATERIALS AND METHODS: 102 consecutive patients with one or more solid malignant hepatic lesions were evaluated by spoiled gradient echo (GRE) sequences with three different echo times (2.4 msec [GRE_2.4], 5.8 msec [GRE_5.8], and 10 msec [GRE_10]) for T2*-weighted imaging in addition to T2-weighted turbo spin echo (TSE) sequence following intravenous SPIO injection. Image qualities of the hepatic contour, vascular landmarks and artifacts were rated by two independent readers using a four-point scale. For quantitative analysis, contrast-to-noise ratio (CNR) was measured in 170 solid focal lesions larger than 1 cm (107 hepatocellular carcinomas, nine cholangiocarcinomas and 54 metastases). RESULTS: GRE_5.8 showed the highest mean points for hepatic contour, vascular anatomy and imaging artifact presence among all of the subjected sequences (p<0.001) and was comparable (p=0.414) with GRE_10 with regard to lesion conspicuity. The mean CNRs were significantly higher (p<0.001) in the following order: GRE_10 (24.4+/-14.5), GRE_5.8 (14.8+/-9.4), TSE (9.7+/-6.3), and GRE_2.4 (7.9+/-6.4). The mean CNRs of CCCs and metastases were higher than those of HCCs for all imaging sequences (p<0.05). CONCLUSION: Regarding overall performances, GRE using a moderate echo time of 5.8 msec can provide the most reliable data among the various fast breath-hold SPIO-enhanced hepatic MRI sequences at 3T unit despite the lower CNR of GRE_5.8 compared to that of GRE_10.

MRI monitoring superparamagnetic iron oxide (SPIO) particles labeling Schwann cells in vitro / 中华显微外科杂志

Objective To investigate the effects of labeling Schwann cells with different concentrations of SPIO, and to investigate the feasibility of in vitro MR imaging. Methods The C57BL/6 mices'Schwann cells were isolated, purified, and then 0.5 × 106, 1.0 × 106, 5.0 × 106 cells were labeled with 25.0 μg/ml, 50.0 μg/ml SPIO. Prussian blue stain and transmission electron microscope (TEM) were performed for showing intracellular iron. The signal intensity of cells were evaluated by 3.0 MRI with different sequences in vitro. Results Different cell population (0.5 × 106, 1.0 × 106,5.0 × 106) were cultured with different concentration SPIO about 24 hours. Dyeing degree of labeling cells stained by Prussion blue gradually deepened from 25.0 μg/ml to 50.0 μg/ml. Transmission electron microscope indicated that iron particles accumulated inendosomes/lysosomes. The MR signal intensity of labeling cells were inversely correlated with the concentration of SPIO groups in T2WI and GRE/30° imaging in vitro. Conclusion Schwann cells could be labeled effectively with SPIO, and MRI could be used to monitor these labeled cells in vitro.

Usefulness of Superparamagnetic Iron Oxide (SPIO) as a Negative Oral Contrast Agent in MR Cholangiopancreatography

PURPOSE: To evaluate value of superparamagnetic iron oxide (SPIO) as a negative oral contrast agent in MR cholangiopancreatography (MRCP). MATERIALS AND METHODS: Forty-eight patients with suspected biliary tract or pancreatic diseases and six healthy volunteers were enrolled in this study. All MR images were obtained using a 1.5 T MR unit. MRCP using fat-suppressed half-Fourier acquisition single-shot turbo spin echo (HASTE) and turbo spin echo (TSE) techniques were performed and reconstructed with maximal intensity projection (MIP). To determine the most optimal concentration of SPIO to obliterate the high signal intensity of water, a phantom experiment was conducted with various concentrations of SPIO-water mixture. Two radiologists evaluated pre- and postcontrast MRCPs. The contrast enhancement was assessed on the basis of loss of signal intensity in the stomach and duodenum. RESULTS: In the phantom experiment, a significant increase of percentage of signal intensity loss (PSIL) occurred in concentration of 22.4 ugFe/ml (Feridex 1 ml diluted with water 500 ml). Postcontrast MRCP showed an improved image quality compared with precontrast images. The rate of improvement in the diagnosis of diseases of the common bile duct and pancreatic duct was 25% (12/48). CONCLUSION: In patients with suspected biliary tract and pancreatic diseases, the SPIO is useful as a negative oral contrast agent for MRCP and provides an improvement of image quality.

Evaluation of Feridex-enhanced MRI in the Diagnosis of Hepatic Lesions / 实用放射学杂志

Objective To evaluate Feridex(superparamagnetic iron oxide,SPIO)enhanced MRI in the diagnosis of hepatic lesions.Methods Feridex-enhanced MRI was performed in 31 patients with CT,or MRI proved or suspected hepatic lesions.T 2WI signal intensity of hepatic parenchyma,lesion and background noise was measured before and after enhancement separately.SNR and CNR of parenchyma and lesion before and after enhancement were calculated.The number of lesions on plain and enhanced scans were observed and alalyzed.Results Post-enhancement SNR of liver significantly decreased (?0.05).Post-enhancement lesion-liver CNR increased significantly (?