BACKGROUND & AIMS: PURPOSE:Magnetic resonance imaging (MRI) has been used to track magnetically labeled human bone marrow-derived mesenchymal stem cells (hBMSCs) in vivo after COX-2 silencing and transplantation into nude rats via tail vein injection. METHODS:In the present study, we knocked down COX-2 expression in hBMSCs through lentivirus transduction. The COX-2 knockdown was confirmed by real-time PCR and Western blotting analyses. Subsequently, we labeled cells with the novel reagent SPIO-Molday ION Rhodamine-B™ (MIRB). The viability, proliferation and differentiation of these cells were assessed in vitro. Labeled lenti-shCOX2 hBMSCs, unlabeled hBMSCs and phosphate-buffered saline (PBS) were individually injected into the tail veins of nude rat models, forming three treatment groups. All nude rats underwent GRE T2*-weighted MRI at 1 h, 7 days and 14 days post-injection. After MRI examination, the animals were sacrificed, and the brain and liver were examined by fluorescence microscopy and Prussian Blue staining. RESULTS:Our results confirmed the successful down-regulation of COX-2 at the mRNA and protein levels in hBMSCs by lentivirus transduction. The viability and differentiation of hBMSCs were not affected by MIRB labeling. After 7 days, hypointense signal void areas in the rat livers were observed on MRI. After 14 days, iron particles were detected in the blood vessels, sinusoids, interlobular septum and capsule tissues of the liver. CONCLUSION:The MIRB-labeled lenti-shCOX2 hBMSCs transplanted into nude rat models via tail vein injection can be detected and monitored in vivo using 3.0 T clinical MRI for up to 14 days after cell transplantation.

背景与目标：

BACKGROUND & AIMS: :There has been recent interest in positive-contrast MRI methods for noninvasive tracking of cells labeled with superparamagnetic iron-oxide nanoparticles. Low-tip-angle balanced steady-state free precession sequences have been used for fast, high-resolution, and flow-insensitive positive-contrast imaging; however, the contrast can be compromised by the limited suppression of the on-resonant and fat signals. In this work, a new technique that produces positive contrast with alternating repetition time steady-state free precession is proposed to achieve robust background suppression for a broad range of tissue parameters. In vitro and in vivo experiments demonstrate the reliability of the generated positive contrast. The results indicate that the proposed method can enhance the suppression level by up to 18 dB compared with conventional balanced steady-state free precession.

背景与目标： : 最近对正对比MRI方法进行非侵入性追踪用超顺磁性氧化铁纳米颗粒标记的细胞产生了兴趣。低尖端角度平衡的稳态自由进动序列已用于快速，高分辨率和对流动不敏感的正对比度成像; 但是，对共振和脂肪信号的有限抑制可能会损害对比度。在这项工作中，提出了一种通过交替重复时间稳态自由进动产生正对比的新技术，以实现对广泛组织参数的鲁棒背景抑制。体外和体内实验证明了产生的阳性对比的可靠性。结果表明，与传统的平衡稳态自由进动相比，该方法可以将抑制水平提高多达18 dB。

BACKGROUND & AIMS: :This study evaluates the robustness of a magnetic resonance (MR) fat quantification method to changes in R2* caused by an intravenous infusion of superparamagnetic iron oxide (SPIO) contrast agent. The R2* and proton density fat fraction (PDFF) were measured in liver and spine in 14 subjects using an investigational sequence (IDEAL IQ) provided by the MR scanner vendor. Measurements were made before and after SPIO infusion. Results showed SPIO significantly increased R2* in both liver (p=8.8×10(-8)) and spine (p=1.3×10(-2)) but PDFFs were not significantly different in either the liver (p=5.5×10(-1)) or the spine (p=5.6×10(-1)). These results confirm that the IDEAL IQ method of fat quantification is robust to changes in R2*.

背景与目标： : 这项研究评估了磁共振 (MR) 脂肪定量方法对静脉输注超顺磁性氧化铁 (SPIO) 造影剂引起的R2 * 变化的鲁棒性。使用MR扫描仪供应商提供的研究序列 (理想智商) 在14名受试者的肝脏和脊柱中测量R2 * 和质子密度脂肪分数 (PDFF)。在SPIO输注之前和之后进行测量。结果显示，SPIO在肝脏 (p = 8.8 × 10(-8)) 和脊柱 (p = 1.3 × 10(-2)) 中均显着增加R2 *，但PDFFs在肝脏 (p = 5.5 × 10(-1)) 或脊柱 (p = 5.6 × 10(-1))。这些结果证实了理想的IQ脂肪定量方法对R2 * 的变化是稳健的。

BACKGROUND & AIMS: PURPOSE:To evaluate the efficacy of ferucarbotran in T2-weighted (T2W) fast spin-echo (FSE) and T2*W gradient-echo (GRE) sequences for characterizing focal liver lesions. MATERIALS AND METHODS:In 68 patients, 46 malignant and 22 benign focal liver lesions were evaluated. Precontrast (NCE) T2W FSE images and contrast-enhanced (CE) T2W FSE and T2*W GRE images were obtained on a 1.5T MR system. Based on signal intensity (SI) measurements in focal lesions and liver parenchyma, the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated for all sequences. The percentage of SI loss (PSIL) in focal lesions after contrast agent (CA) application was calculated for the T2W FSE sequence. Qualitative analyses were performed to assess image quality and lesion conspicuity obtained with the CE-T2W FSE and CE-T2*W GRE sequences. RESULTS:The mean PSIL was higher in solid benign lesions than in malignant lesions (39.6% vs. 3.2%, P<0.05). With a threshold PSIL of 25%, the sensitivity and specificity for characterizing malignant lesions were 97.8% and 92.9%, respectively. The mean CNR of the malignant lesions was higher in the CE-T2*W sequence than in the CE- and NCE-T2W FSE sequences (29.9 vs. 22.7 (P<0.01) vs. 12.8 (P<0.01)). CE-T2*W images showed a superior image quality and lesion conspicuity (P<0.05) compared to the CE-T2W FSE sequence. CONCLUSION:The PSIL can be an accurate tool for characterizing benign and malignant lesions. The addition of a CE-T2*W GRE sequence is helpful for the detection and characterization of malignant lesions.

背景与目标：

BACKGROUND & AIMS: OBJECTIVE:To evaluate transplanted porcine pancreatic islets in the kidney capsules of diabetic mice using a clinically approved superparamagnetic iron oxide (SPIO) and a 1.5T MR scanner. MATERIALS AND METHODS:Various numbers of porcine pancreatic islets labeled with Resovist, a carboxydextran-coated SPIO, were transplanted into the kidney capsules of normal mice and imaged with a 3D FIESTA sequence using a 1.5T clinical MR scanner. Labeled (n = 3) and unlabeled (n = 2) islets were transplanted into the kidney capsules of streptozotocin-induced diabetic mice. Blood glucose levels and MR signal intensities were monitored for 30 days post-transplantation. RESULTS:There were no significant differences in viability or insulin secretion between labeled and unlabeled islets. A strong correlation (r(2) > 0.94) was evident between the number of transplanted islets and T(2) relaxation times quantified by MRI. Transplantation with labeled or unlabeled islets helped restore normal sustained glucose levels in diabetic mice, and nephrectomies induced the recurrence of diabetes. The MR signal intensity of labeled pancreatic islets decreased by 80% over 30 days. CONCLUSION:The transplantation of SPIO-labeled porcine islets into the kidney capsule of diabetic mice allows to restore normal glucose levels, and these islets can be visualized and quantified using a 1.5T clinical MR scanner.

背景与目标：

BACKGROUND & AIMS: BACKGROUND:The objective of our study was to assess the negative predictive value (NPV) of double-contrast MRI (DC-MRI) with SPIO and gadolinium, and to determine the role of DC-MRI in screening for hepatocellular carcinoma (HCC) in cirrhotic patients. METHODS:We retrospectively included 160 DC-MRI scans done as second-line investigations in 119 patients with cirrhosis over a 25-month period. Two radiologists independently classified the MRI scans as strongly suggesting HCC (HCC Group), showing benign nodules (benign nodules Group), showing no nodules (no-nodules Group) or indeterminate; they assigned a diagnostic confidence score (DCS) using a 0-10 scale. The reference standard was histology or results of follow-up investigations. Mean follow-up was 16.9 months (12-28 months). RESULTS:The radiologists disagreed for two scans (kappa = 0.98). Of 112 scans [benign nodules Group (n = 32) and no-nodules Group (n = 80)], 11 were excluded (3 patients lost to follow-up and 8 who died with no known cancer) while a HCC was detected during follow-up in 8 patients, yielding a NPV of 92% (93/101) (95% confidence interval, 85%-97%). The DCS was in the 4-6 range (indicating uncertainty) for only 6 (3.75%) scans. CONCLUSIONS:DC-MRI is reliable and reproducible. Its high NPV suggests a role as a second-line investigation after ultrasonography, for HCC screening.

背景与目标：

BACKGROUND & AIMS: PURPOSE:The purpose of this study was to determine whether MR with and without SPIO (AMI-25) could replace spiral-CTAP in the staging of colorectal adenocarcinoma. MATERIAL AND METHODS:Thirty-five patients were studied prospectively by means of i.v. contrast-enhanced spiral-CT, spiral-CTAP, and MR of the liver. MR imaging was performed before and after infusion of AMI-25. Diagnoses were compared to intraoperative findings (n = 35) which included intraoperative ultrasound (n = 21), and follow-up CT (n = 18). RESULTS AND CONCLUSION:Fifteen patients were found to have a total number of 53 liver metastases and 43 benign lesions were detected. Evaluation was performed in four different ways: 1) i.v. contrast-enhanced spiral-CT; 2) i.v. contrast-enhanced spiral-CT + spiral-CTAP; 3) plain MR; 4) plain MR + SPIO-enhanced MR. I.v. contrast-enhanced spiral-CT, spiral-CTAP and SPIO-enhanced MR identified patients with liver metastases with equal sensitivity. However, owing to its significantly higher sensitivity, based on a lesion-by-lesion analysis, spiral-CTAP cannot be replaced by SPIO-enhanced MR in patients who are to undergo liver resection. A limitation in spiral-CTAP is its relatively low specificity.

背景与目标：

BACKGROUND & AIMS: :Multifunctional nanoparticles combining therapy and imaging have the potential to improve cancer treatment by allowing personalized therapy. Herein, we aimed to compare in vivo different strategies in terms of targeting capabilities: (1) passive targeting via the EPR effect, (2) active targeting of αvβ3 integrin via RGD grafting, (3) magnetic targeting via a magnet placed on the tumor and (4) the combination of magnetic targeting and active targeting of αvβ3 integrin. For a translational approach, PLGA-based nanoparticles loaded with paclitaxel and superparamagnetic iron oxides were used. Electron Spin Resonance spectroscopy and Magnetic Resonance Imaging (MRI) were used to both quantify and visualize the accumulation of multifunctional nanoparticles into the tumors. We demonstrate that compared to untargeted or single targeted nanoparticles, the combination of both active strategy and magnetic targeting drastically enhanced (i) nanoparticle accumulation into the tumor tissue with an 8-fold increase compared to passive targeting (1.12% and 0.135% of the injected dose, respectively), (ii) contrast in MRI (imaging purpose) and (iii) anti-cancer efficacy with a median survival time of 22 days compared to 13 for the passive targeting (therapeutic purpose). Double targeting of nanoparticles to tumors by different mechanisms could be a promising translational approach for the management of therapeutic treatment and personalized therapy.

背景与目标： : 结合治疗和成像的多功能纳米颗粒有可能通过允许个性化治疗来改善癌症治疗。在此，我们旨在比较体内靶向能力方面的不同策略 :( 1) 通过EPR效应进行被动靶向，(2) 通过RGD移植对 αvβ3整联蛋白进行主动靶向，(3) 通过放置在肿瘤上的磁体进行磁靶向，以及 (4) 磁靶向和 αvβ3整合素的主动靶向的组合。对于翻译方法，使用了载有紫杉醇和超顺磁性氧化铁的基于PLGA的纳米颗粒。电子自旋共振波谱和磁共振成像 (MRI) 用于量化和可视化多功能纳米颗粒在肿瘤中的积累。我们证明，与非靶向或单一靶向纳米颗粒相比，主动策略和磁靶向的组合大大增强了 (i) 纳米颗粒积累到肿瘤组织中，与被动靶向相比增加了8倍 (分别为注射剂量的1.12% 和0.135%)，(ii) MRI (成像目的) 和 (iii) 抗癌疗效的对比，中位生存时间为22天，而被动靶向 (治疗目的) 为13天。通过不同的机制将纳米颗粒双重靶向肿瘤可能是治疗治疗和个性化治疗管理的一种有前途的转化方法。

BACKGROUND & AIMS: :The tumor-detecting capacity and clinical usefulness of superparamagnetic iron oxide (SPIO) magnetic resonance imaging (MRI) were examined in patients with hepatocellular carcinoma. The tumor detection rate of SPIO-MRI (64.5%) was comparable to those of dynamic computed tomography (CT) and plain MRI, but lower than that for Gd dynamic MRI (93.5%; P < 0.01%). A combination of Gd dynamic MRI and SPIO-MRI improved the detection rate; further, the tumor stage with respect to tumor blood-flow pattern was predicted by combining plain MRI with SPIO-MRI. This combination procedure may also be useful for selecting therapeutic strategies.

背景与目标： : 在肝细胞癌患者中检查了超顺磁性氧化铁 (SPIO) 磁共振成像 (MRI) 的肿瘤检测能力和临床实用性。SPIO-MRI (64.5%) 的肿瘤检出率与动态计算机断层扫描 (CT) 和普通MRI相当，但低于Gd动态MRI (93.5%; P <0.01%)。Gd动态MRI和SPIO-MRI的组合提高了检出率; 此外，通过将普通MRI与SPIO-MRI相结合，可以预测肿瘤血流模式的肿瘤分期。此组合程序也可能有助于选择治疗策略。

BACKGROUND & AIMS: :The survivin gene is highly expressed in pancreatic cancer. The purpose of this study was to design and synthesize functionalized magnetic iron oxide nanoparticles (MNPs) targeting survivin gene for the detection of pancreatic cancer. The pancreatic cancer cell line BxPC-3 with survivin gene expression was selected in this study. The healthy lung fibroblast cell was used as a control. Chitosan-coated MNPs (CS@MNPs) and antisense oligodeoxynucleotide of survivin gene were conjugated to MNPs to give Sur-MNPs. Fourier transform infrared spectroscopy was performed to confirm the conjunction of chitosan. The interactions of MNPs, CS@MNPs, and Sur-MNPs in BxPC-3 cells were observed, recorded and analyzed. The size, morphology, cell uptake, cytotoxicity and stability of those particles were assessed by transmission electron microscope, Prussian blue staining, MTT assay and agarose gel electrophoresis. The magnetic resonance signal intensities of pancreatic cells labeled with CS@MNPs and MNPs, and Sur-MNPs, were compared on T₂-weighted images. The results demonstrated that the level of cellular uptake of CS@MNPs was higher than that of naked MNPs. The Sur-MNPs had a suitable size (12 nm sized core), high stability, no cytotoxicity and good water dispersion. Sur-MNPs did not accumulate in healthy lung fibroblast cells, while being taken up by BxPC-3 cells. The Sur-MNPs in BxPC-3 cells could be visualized on T₂-weighted images, which suggested that Sur-MNPs could be used to detect the expression of survivin gene. Thus, Sur-MNPs may be a potential molecular imaging probe targeting survivin gene for early detection of pancreatic cancer cells.

背景与目标： : survivin基因在胰腺癌中高表达。目的设计并合成靶向survivin基因的功能化磁性氧化铁纳米颗粒 (MNPs)，用于胰腺癌的检测。本研究选择了BxPC-3 survivin基因表达的胰腺癌细胞系。健康的肺成纤维细胞用作对照。壳聚糖包被的MNPs (CS @ MNPs) 和survivin基因的反义寡核苷酸与MNPs偶联，得到Sur-MNPs。进行傅里叶变换红外光谱以确认壳聚糖的结合。观察、记录和分析BxPC-3细胞中MNPs、CS @ MNPs和Sur-MNPs的相互作用。通过透射电子显微镜，普鲁士蓝染色，MTT测定和琼脂糖凝胶电泳评估这些颗粒的大小，形态，细胞摄取，细胞毒性和稳定性。在t 2加权图像上比较了用CS @ MNPs和MNPs以及Sur-MNPs标记的胰腺细胞的磁共振信号强度。结果表明，CS @ MNPs的细胞摄取水平高于裸MNPs。Sur-MNPs具有合适的尺寸 (12  nm大小的芯)，高稳定性，无细胞毒性和良好的水分散性。Sur-MNPs在健康的肺成纤维细胞中没有积累，而被BxPC-3细胞占据。BxPC-3细胞中的Sur-MNPs可以在t 2加权图像上显示，这表明Sur-MNPs可用于检测survivin基因的表达。因此，Sur-MNPs可能是靶向survivin基因的潜在分子成像探针，可用于早期检测胰腺癌细胞。

BACKGROUND & AIMS: PURPOSE:To compare conspicuity of zones of ablation on nonenhanced, gadopentetate dimeglumine-(Gd-DTPA) and ferucarbotran-(SPIO)-enhanced magnetic resonance (MR) images. MATERIALS AND METHODS:In all, 33 radiofrequency ablations (RFA) were performed in 17 healthy porcine livers at 1.5T MR imaging 1 day and 2 and 4 weeks after RFA: T2-weighted (w) ultra turbo spin echo (UTSE), proton density (PD)-w UTSE, T1-w gradient echo (GRE) pre- and 5 minutes postcontrast administration, dynamic T1-w GRE during Gd-DTPA (Magnevist) or SPIO (Resovist) administration, T2-w UTSE, and PD-w UTSE sequences 10 minutes after SPIO administration. Regions of interest (ROIs) for contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) were drawn in consensus by two radiologists. RESULTS:PD-w SPIO-enhanced images (23.5 +/- 5.5) showed higher liver-to-lesion CNR than T1-w GRE Gd-DTPA-enhanced images (13.5 +/- 6.1) 1 day after RFA (P < or = 0.05). At all other timepoints, liver-to-lesion CNR of PD-w and T2-w SPIO-enhanced images did not differ significantly from T1-w GRE Gd-DTPA-enhanced images (P > or = 0.05). Nonenhanced T2-w images revealed lower liver-to-lesion CNR (7.0 +/- 7.5/6.5 +/- 5.9/6.8 +/- 5.0, 1 day/2 weeks/4 weeks, respectively) than T2-w SPIO-enhanced (17.4 +/- 4.8/15.3 +/- 4.5/14.2 +/- 5.7), PD-w SPIO-enhanced (23.5 +/- 5.5/16.9 +/- 3.6, 1 day/2 weeks), and T1-w Gd-DTPA-enhanced (15.3 +/- 3.6/12.7 +/- 3.5, 2/4 weeks) images (P < or = 0.05). Liver-to-lesion CNR of SPIO-enhanced dynamic T1-w GRE images after 30, 80, 150, and 240 seconds did not change significantly over time (P > or = 0.05). CONCLUSION:One day after RFA lesion conspicuity on PD-w ferucarbotran-enhanced images is better than on T1-w GRE Gd-DTPA-enhanced images. At all other timepoints, ferucarbotran is not superior to gadolinium. Ferucarbotran- and gadolinium-enhanced images improve lesion conspicuity compared with nonenhanced T2-w images at all timepoints.

背景与目标：

BACKGROUND & AIMS: :Along with the development of modern imaging technologies, contrast agents play increasingly important roles in both clinical applications and scientific research. Super-paramagnetic iron oxide (SPIO) nanoparticles, a negative contrast agent, have been extensively used in magnetic resonance imaging (MRI), such as in vivo labeling and tracking of cells. However, there still remain many challenges, such as in vivo quantification of SPIO nanoparticles. In this work, an MR phase gradient-based method was proposed to quantify the SPIO nanoparticles. As a calibration, a phantom experiment using known concentrations (10, 25, 50, 100, 150 and 250 µg/ml) of SPIO was first conducted to verify the proposed quantification method. In a following in vivo experiment, C6 glioma cells labeled with SPIO nanoparticles were implanted into flanks of four mice, which were scanned 1-3 days post-injection for in vivo quantification of SPIO concentration. The results showed that the concentration of SPIO nanoparticles could be determined in both phantom and in vivo experiments using the developed MR phase gradients approach.

背景与目标： 随着现代成像技术的发展，造影剂在临床应用和科学研究中发挥着越来越重要的作用。超顺磁性氧化铁 (SPIO) 纳米颗粒是一种阴性造影剂，已广泛用于磁共振成像 (MRI)，例如细胞的体内标记和跟踪。然而，仍然存在许多挑战，例如SPIO纳米颗粒的体内定量。在这项工作中，提出了一种基于MR相位梯度的方法来量化SPIO纳米颗粒。作为校准，首先进行使用已知浓度 (10、25、50、100、150和250 μ g/ml) 的SPIO的幻像实验，以验证所提出的定量方法。在随后的体内实验中，将用SPIO纳米颗粒标记的C6神经胶质瘤细胞植入四只小鼠的侧面，在注射后1-3天对其进行扫描，以体内定量SPIO浓度。结果表明，使用开发的MR相位梯度方法，可以在体模实验和体内实验中确定SPIO纳米颗粒的浓度。

BACKGROUND & AIMS: :The aim of this prospective study was to compare the diagnostic role of superparamagnetic iron oxide (SPIO)-enhanced liver magnetic resonance imaging (MRI) versus gadobenate dimeglumine (GbD)-enhanced MRI and computed tomography (CT) investigations for detection of small (less than 1cm) colorectal liver metastases (LMs) of colorectal cancer. Seventy-eight LMs in 16 patients were evaluated with dynamic CT imaging, GbD-enhanced dynamic MR imaging and SPIO-enhanced MR imaging. Two radiologists were reviewed the LMs separately. Agreement between the readers and three algorithms was analyzed. Differences between the lesion detection ratios of the methods were analyzed by two proportion z test. Sensitivity values of each modality were also calculated. Interobserver agreement values with kappa analysis were found to be the best for three modalities and kappa values were 0.866, 0.843, and 1.0 respectively. For all 78 LMs, SPIO-enhanced MRI detected all lesions (100% sensitivity). This sensitivity value was higher than GbD-enhanced MRI, and there was a significant difference (p < 0.05). GbD-enhanced MRI depicted 71 lesions and this modality could not detected 7 lesions (91% sensitivity). This modality had moderate sensitivity, and this value is greater than CT imaging, so there was a significant difference also (p < 0.05). Dynamic triphasic CT imaging detected 64 (R1) and 65 (R2) LMs. This modality had the lowest sensitivity (R1: 0.82, R2: 0.83 respectively). Only SPIO-enhanced MRI was able to detect all LMs less than 1cm. LMs were the best detected with SPIO-enhanced MRI. We recommend SPIO-enhanced MRI to be the primary alternative modality especially for diagnosis of small colorectal LMs.

背景与目标： : 这项前瞻性研究的目的是比较超顺磁性氧化铁 (SPIO) 增强的肝脏磁共振成像 (MRI) 与加多本酸二甲胺 (GbD) 增强的MRI和计算机断层扫描 (CT) 检查在检测小 (小于1厘米) 结直肠肝转移 (LMs) 中的诊断作用结直肠癌。对16例患者的78例LMs进行了动态CT成像，GbD增强的动态MR成像和SPIO增强的MR成像评估。两名放射科医生分别接受了LMs检查。分析了读者与三种算法之间的一致性。通过两个比例z检验分析了方法的病变检测率之间的差异。还计算了每种模式的灵敏度值。发现具有kappa分析的观察者间一致性值对于三种模式是最佳的，并且kappa值分别为0.866，0.843和1.0。对于所有78个LMs，SPIO增强MRI检测到所有病变 (100% 敏感性)。该灵敏度值高于GbD增强MRI，差异有统计学意义 (p <0.05)。GbD增强的MRI描绘了71个病变，并且这种方式无法检测到7个病变 (91% 敏感性)。这种模式具有中等敏感性，并且该值大于CT成像，因此也存在显着差异 (p <0.05)。动态三相CT成像检测到64 (R1) 和65 (R2) LMs。该模态具有最低的灵敏度 (分别为R1: 0.82，R2: 0.83)。只有SPIO增强的MRI能够检测到小于1厘米的所有LMs。用SPIO增强MRI检测到LMs最好。我们建议SPIO增强MRI是主要的替代方式，尤其是对于小结直肠LMs的诊断。

BACKGROUND & AIMS: PURPOSE:To evaluate whether diffusion-weighted imaging (DWI) improves the detection of hepatocellular carcinoma (HCC) on super paramagnetic iron oxide (SPIO)-enhanced MRI. MATERIALS AND METHODS:This retrospective study group consisted of 30 patients with 50 HCC nodules who underwent MRI at 1.5 Tesla. Two combined MR sequence sets were compared for detecting HCC: SPIO-enhanced MRI (axial T2-weighted fast spin-echo (FSE) and T1-/T2*-weighted fast field echo (FFE) scanned before and after administration of ferucarbotran) and SPIO-enhanced MRI + DWI (SPIO-enhanced MRI with axial DWI scanned before and after administration of ferucarbotran). Three blinded readers independently reviewed for the presence of HCC on a segment-by-segment basis using a four-point confidence scale. The performance of the two combined MR sequence sets was evaluated using receiver operating characteristic (ROC) analysis. RESULTS:The average area under the ROC curve (Az) of the three readers for the SPIO-enhanced MRI + DWI set (0.870 +/- 0.046) was significantly higher that that for the SPIO-enhanced MRI set (0.820 +/- 0.055) (P = .025). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for detection of HCC were 66.0%, 98.0%, 90.0%, and 91.4%, respectively, for the SPIO-enhanced MRI set, and 70.0%, 98.6%, 92.9%, and 92.4%, respectively, for the SPIO-enhanced MRI + DWI set. CONCLUSION:The SPIO-enhanced MRI + DWI set outperformed the SPIO-enhanced MRI set for depicting HCC.

背景与目标：

BACKGROUND & AIMS: :In vivo detection of transplanted stem cells is requisite for improving stem cell-based treatments by developing a thorough understanding of their therapeutic mechanisms. MRI tracking of magnetically labeled cells is non-invasive and is suitable for longitudinal studies. Molday ION Rhodamine-B™ (MIRB) is a new superparamagnetic iron oxide (SPIO) contrast agent specifically formulated for cell labeling and is readily internalized by non-phagocytic cells. This investigation characterizes mesenchymal stem cell (MSC) labeling and MR imaging properties of this new SPIO agent. Effects of MIRB on MSC viability and differentiation as well as cellular loading properties were assessed for MSC labeled with MIRB at concentrations from 5 to 100 µg Fe/ml. Labeled MSC were evaluated, in vitro, on a clinical 1.5 T MRI. Optimal scanning sequences and imaging parameters were determined based on contrast-to-noise ratio and contrast modulation. Relaxation rates (1/T(2)*) for gradient-echo sequences were approximated and an idealized limit of detection was established. MIRB labeling did not affect MSC viability or the ability to differentiate into either bone or fat. Labeling efficiency was found to be approximately 95% for labeling concentrations at or above 20 µg Fe/ml. Average MIRB per MSC ranged from 0.7 pg Fe for labeling MIRB concentration of 5 µg Fe/ml and asymptotically approached a value of 20-25 pg Fe/MSC as labeling concentration increased to 100 µg Fe/ml. MRI analysis of MIRB MSC revealed long echo time, gradient echo sequences to provide the most sensitivity. Limit of detection for gradient echo sequences was determined to be less than 1000 MSC, with approximately 15 pg Fe/MSC (labeled at 20 µg Fe/ml). These investigations have laid the groundwork and established feasibility for the use of this contrast agent for in vivo MRI detection of MSC. Properties evaluated in this study will be used as a reference for tracking labeled MSC for in vivo studies.

背景与目标： : 移植干细胞的体内检测是通过全面了解其治疗机制来改善基于干细胞的治疗的必要条件。磁标记细胞的MRI跟踪是非侵入性的，适用于纵向研究。摩尔迪离子若丹明-B™(MIRB) 是一种新型的超顺磁性氧化铁 (SPIO) 造影剂，专门用于细胞标记，易于被非吞噬细胞内化。这项研究表征了这种新型SPIO试剂的间充质干细胞 (MSC) 标记和MR成像特性。MIRB对MSC活力和分化以及细胞负载特性的影响评估了用浓度为5至100 μ g Fe/ml的MIRB标记的MSC。在临床1.5 T MRI上体外评估标记的MSC。根据对比度噪声比和对比度调制确定最佳扫描序列和成像参数。近似梯度回波序列的弛豫率 (1/T(2)*)，并建立了理想的检测极限。MIRB标记不会影响MSC的生存能力或分化为骨骼或脂肪的能力。发现标记浓度在20 µ g Fe/ml或高于20 µ g Fe/ml时，标记效率约为95%。每个MSC的平均MIRB范围为0.7 pg Fe，用于标记5 μ g Fe/ml的MIRB浓度，并且随着标记浓度增加到100 μ g Fe/ml，渐近地接近20-25 pg Fe/MSC的值。MIRB MSC的MRI分析显示，较长的回波时间，梯度回波序列提供了最大的灵敏度。梯度回波序列的检测限被确定为小于1000 MSC，约为15 pg Fe/MSC (标记为20μgfe/ml)。这些研究为将这种造影剂用于MSC的体内MRI检测奠定了基础并确定了可行性。在这项研究中评估的特性将用作跟踪体内研究的标记MSC的参考。