BACKGROUND & AIMS: PURPOSE:To assess the detectability of single magnetically labeled mesenchymal stem cells (MSC) in-vitro on a clinical 3T MR scanner using a small animal volume coil. MATERIALS AND METHODS:GFP-transfected MSC were magnetically labeled with superparamagnetic iron oxide particles (SPIO) while applying different dosages of iron (56 vs. 560 microg Fe/ml). The cellular iron content was determined with atomic absorption spectrometry (AAS). Single labeled MSC were displayed in a culture flask using MR imaging and microscopy. Special cell phantoms were designed to examine the detection of labeled MSC with MR imaging in a spatial model. A T2*-weighted 3D gradient echo sequence with isotropic spatial resolution of 150 to 500 microm (3) was used for image acquisition. The detection of labeled MSC in the cell phantoms was quantitatively evaluated using an automated image analysis. Statistical analysis was performed with a significance level of p < 0.05. RESULTS:The labeling of MSC yielded a mean cellular iron content of 1.5 +/- 0.17 pg Fe/cell (56 microg Fe/ml) and 8.3 +/- 1.85 pg Fe/cell (560 microg Fe/ml). Examination of the culture flasks showed single magnetically labeled MSC centered in much larger MR signal voids. The detection and quantification of single MSC in cell phantoms were feasible for spatial resolutions of 150 microm and 200 microm. Cells with a lower SPIO content (1.5 +/- 0.17 pg Fe/cell) were detected in 14.2 +/- 4.2 % (150 microm) and 7.7 +/- 3.8 % (200 microm). MSC with a higher cellular SPIO content (8.3 +/- 1.85 pg Fe/cell) revealed significantly higher occurrences at both spatial resolutions with 81.4 +/- 5.8 % (150 microm) and 59.9 +/- 12.4 % (200 microm), respectively. Regarding the spatial resolution (150 vs. 200 microm), significantly different detection rates were determined only for MSC with the higher SPIO content (8.3 +/- 1.85 pg Fe/cell). CONCLUSION:Detection of single magnetically labeled MSC is feasible on a clinical 3T MR scanner with a small animal volume coil at isotropic spatial resolutions of 150 microm and 200 microm. The number of detected cells is influenced by the cellular iron content and the spatial resolution.

背景与目标：

BACKGROUND & AIMS: PURPOSE:To evaluate heating efficacy of superparamagnetic iron oxide nanoparticles (SPIO) for electromagnetic ablation (EMA) of osteoid osteoma (OO) using an ex vivo model compared to radiofrequency ablation (RFA) and microwave ablation (MWA). METHODS:A model for OO using sliced bovine tibia and sliced muscle tissue was developed. A bone cavity filled with either a mixture of SPIO and agarose or pure agarose (control group) was established. EMA was performed using an experimental system, RFA and MWA using clinically approved systems, and the ablation protocols recommended by the vendor. For temperature measurements, fiberoptic temperature probes were inserted inside the cavity, on the outside of the periosteum, and at a 5 mm distance to the periosteum. RESULTS:Maximum temperatures with or without SPIO in the nidus were as follows: EMA: 79.9 ± 2.5/22.3 ± 0.7 °C; RFA: 95.1 ± 1.8/98.6 ± 0.9 °C; MWA: 85.1 ± 10.8/83.4 ± 9.62 °C. In RFA with or without SPIO significantly higher temperatures were achieved in the nidus compared to all other groups (p < 0.05). In MWA significantly higher temperatures were observed in the 5 mm distance to the periosteum compared to EMA and RFA with or without SPIO (p < 0.05). In MWA temperature decrease between nidus and the 5 mm distance to the periosteum was significantly lower than in RFA with or without SPIO (p < 0.0001). In MWA without SPIO temperature decrease was significantly lower than in the EMA group (p < 0.05). CONCLUSION:In the experimental setting, ablation of OO is safe and effective using EMA. It is less invasive than RFA and MWA, and it theoretically allows repeated treatments without repeated punctures. In comparison, the highest temperatures in the nidus are reached using RFA.

背景与目标：

BACKGROUND & AIMS: PURPOSE:To evaluate superparamagnetic iron oxide (SPIO)-enhanced breathhold T2-weighted GRASE imaging in detection and characterization of focal liver lesions. MATERIALS AND METHODS:In 30 patients (including 20 with cirrhosis) with 39 malignant and 25 benign lesions, gradient- and spin-echo (GRASE) images with two echo times (75 and 90 msec; GRASE75 and GRASE90) were obtained prior to and following administration of SPIO, and compared with respiratory-triggered and breathhold fast spin-echo (RT-FSE and BH-FSE) images. Two readers evaluated image quality and reviewed 240 liver segments for sensitivity and specificity. Signal-to-noise ratio (SNR), and its reduction in liver and spleen after administration of SPIO, and lesion-to-liver contrast-to-noise ratio (CNR) were measured. RESULTS:Compared with RT-FSE and BH-FSE, GRASE reduced scan time by 77% to 82% and 21% to 27%, respectively. The image qualities with BH-FSE and GRASE75 were higher than with BH-FSE and GRASE90. BH-FSE showed higher specificity than RT-FSE and GRASE90, but otherwise there were no significant differences between pulse sequences for sensitivity or specificity. The mean SNR and CNR of the lesions with RT-FSE were significantly higher than with the other methods. SPIO-induced signal reduction of liver SNR was smallest with BH-FSE. CONCLUSION:GRASE is faster and more sensitive to SPIO than FSE, but its sensitivity and specificity were slightly inferior to those of BH-FSE. Image quality is a current limitation.

背景与目标：

BACKGROUND & AIMS: :An in vitro MR-assay for superparamagnetic iron oxide (SPIO) particle cell labelling assessment via three-dimensional quantitative T(2) (*) MR microscopy was proposed. On high-resolution images, and due to the high susceptibility difference between the particles and the surrounding medium, SPIO internalized in cells induces signal loss which may be counted and measured on T(2) (*) maps. The increase in both labelled cell percentage and the average perturbation volume with an added amount of iron in the incubation medium proved that intracellular iron uptake is dependent upon the initial concentration of incubation iron. It also proved that the observed increases in total cellular iron uptake measured by inductively coupled plasma optical emission spectroscopy are due to both an increase in the iron mass per cell and also an increase in labelled cell concentration. MR results were compared with Prussian blue staining histology. The sensitivity of the MR methodology was then used to distinguish labelling differences for two different types of particle coating. The MRI-assay we proposed is a compulsory tool to optimize labelling efficiency in order to improve in vivo cell detection. Key parameters for detection, such as the percentage of cell labelling, the effect on the image for a given amount of internalized iron and labelling distribution among a cell population, are easily obtained. The comparison of different contrast agents for labelling one cell type, the assessment of one type of contrast agent for labelling different cell types and/or the evaluation of labelling strategies, are possible without having recourse to classical methods, and provide improved accuracy, since the principle is based on intracellular relaxivity.

背景与目标： : 提出了一种通过三维定量T(2) (*) MR显微镜评估超顺磁性氧化铁 (SPIO) 颗粒细胞标记的体外MR测定法。在高分辨率图像上，并且由于颗粒与周围介质之间的高敏感性差异，在细胞中内化的SPIO会引起信号损失，可以在T(2) (*) 图上进行计数和测量。标记细胞百分比的增加和平均扰动体积的增加，在孵育培养基中添加了大量的铁，证明了细胞内铁的摄取取决于孵育铁的初始浓度。还证明，通过电感耦合等离子体发射光谱法测得的总细胞铁吸收量的观察到的增加是由于每个细胞的铁质量增加以及标记细胞浓度的增加。将MR结果与普鲁士蓝染色组织学进行比较。然后使用MR方法的灵敏度来区分两种不同类型的颗粒涂层的标记差异。我们提出的MRI分析是优化标记效率以改善体内细胞检测的强制性工具。易于获得用于检测的关键参数，例如细胞标记的百分比，给定量的内化铁对图像的影响以及细胞群之间的标记分布。用于标记一种细胞类型的不同造影剂的比较、用于标记不同细胞类型的一种造影剂的评估和/或标记策略的评估是可能的，而无需求助于经典方法，并且提供了改进的准确性，因为该原理是基于细胞内松弛。

BACKGROUND & AIMS: BACKGROUND:The complement system is a key component of innate immunity implicated in the neutralization and clearance of invading pathogens. Dextran coated superparamagnetic iron oxide (SPIO) nanoparticle is a promising magnetic resonance imaging (MRI) contrast agent. However, dextran SPIO has been associated with significant number of complement-related side effects in patients and some agents have been discontinued from clinical use (e.g., Feridex™). In order to improve the safety of these materials, the mechanisms of complement activation by dextran-coated SPIO and the differences between mice and humans need to be fully understood. METHODS:20 kDa dextran coated SPIO nanoworms (SPIO NW) were synthesized using Molday precipitation procedure. In vitro measurements of C3 deposition on SPIO NW using sera genetically deficient for various components of the classical pathway (CP), lectin pathway (LP) or alternative pathway (AP) components were used to study mechanisms of mouse complement activation. In vitro measurements of fluid phase markers of complement activation C4d and Bb and the terminal pathway marker SC5b-C9 in normal and genetically deficient sera were used to study the mechanisms of human complement activation. Mouse data were analyzed by non-paired t-test, human data were analyzed by ANOVA followed by multiple comparisons with Student-Newman-Keuls test. RESULTS:In mouse sera, SPIO NW triggered the complement activation via the LP, whereas the AP contributes via the amplification loop. No involvement of the CP was observed. In human sera the LP together with the direct enhancement of the AP turnover was responsible for the complement activation. In two samples out of six healthy donors there was also a binding of anti-dextran antibodies and C1q, suggesting activation via the CP, but that did not affect the total level of C3 deposition on the particles. CONCLUSIONS:There were important differences and similarities in the complement activation by SPIO NW in mouse versus human sera. Understanding the mechanisms of immune recognition of nanoparticles in mouse and human systems has important preclinical and clinical implications and could help design more efficient and safe nano-formulations.

背景与目标：

BACKGROUND & AIMS: :The susceptibility gradients generated by super-paramagnetic iron oxide (SPIO) nanoparticles make them an ideal contrast agent in magnetic resonance imaging. Traditional quantification methods for SPIO nanoparticle-based contrast agents rely on either mapping T₂* values within a region or by modeling the magnetic field inhomogeneities generated by the contrast agent. In this study, a new model-based SPIO quantification method is introduced. The proposed method models magnetic field inhomogeneities by approximating regions containing SPIOs as ensembles of magnetic dipoles, referred to as the finite perturber method. The proposed method was verified using data acquired from a phantom and in vivo mouse models. The phantom consisted of an agar solution with four embedded vials, each vial containing known but different concentrations of SPIO nanoparticles. Gaussian noise was also added to the phantom data to test performance of the proposed method. The in vivo dataset was acquired using five mice, each of which was subcutaneously implanted in the flanks with 1 × 10(5) labeled and 1 × 10(6) unlabeled C6 glioma cells. For the phantom data set, the proposed algorithm was generate accurate estimations of the concentration of SPIOs. For the in vivo dataset, the method was able to give estimations of the concentration within SPIO-labeled tumors that are reasonably close to the known concentration.

背景与目标： : 超顺磁性氧化铁 (SPIO) 纳米颗粒产生的磁化率梯度使其成为磁共振成像中的理想造影剂。基于SPIO纳米颗粒的造影剂的传统定量方法依赖于在区域内映射t 2*值或通过对造影剂产生的磁场不均匀性进行建模。在这项研究中，介绍了一种新的基于模型的SPIO量化方法。所提出的方法通过近似包含SPIOs的区域作为磁偶极子的集合来建模磁场不均匀性，称为有限扰动法。使用从体模和体内小鼠模型获得的数据验证了所提出的方法。幻影由带有四个嵌入式小瓶的琼脂溶液组成，每个小瓶包含已知但浓度不同的SPIO纳米颗粒。还将高斯噪声添加到幻像数据中，以测试所提出方法的性能。使用五只小鼠获得体内数据集，每只小鼠皮下植入1 × 10(5) 标记和1 × 10(6) 未标记的C6神经胶质瘤细胞。对于幻像数据集，所提出的算法是生成SPIOs浓度的准确估计。对于体内数据集，该方法能够给出与已知浓度相当接近的SPIO标记肿瘤内浓度的估计值。

BACKGROUND & AIMS: PURPOSE:To label human monocytes with superparamagnetic iron oxide (SPIO) and compare labeling efficiency with that of ultrasmall SPIO (USPIO) and evaluate the effect of iron incorporation on cell viability, migratory capacity, and proinflammatory cytokine production. MATERIALS AND METHODS:The study was approved by the institutional ethics committee; informed consent was obtained from donors. Freshly isolated human monocytes were labeled with iron particles of two sizes, USPIOs of 30 nm and SPIOs of 150 nm, for 1.5 hours in culture medium containing 0.1, 0.5, 1.0, and 3.7 mg of iron per milliliter. Labeling efficiency was determined with relaxation time magnetic resonance (MR) imaging (4.7 T) and Prussian blue staining for presence of intracellular iron. Cell viability was monitored; migratory capacity of monocytes after labeling was evaluated by using an in vitro assay with monolayers of brain endothelial cells. Levels of proinflammatory cytokines, interleukin (IL) 1 and IL-6, were measured with enzyme-linked immunosorbent assay 24 hours after labeling. Data were analyzed with Student t test or two-way analysis of variance followed by a multiple-comparison procedure. RESULTS:R2 relaxation rates increased for cell samples incubated with SPIOs, whereas rates were not affected for samples incubated with highest concentration of USPIOs. Labeling monocytes with SPIOs (1.0 mg Fe/mL) resulted in an R2 of 13.1 sec(-1) +/- 0.8 (standard error of the mean) (7 sec(-1) +/- 0.2 for vehicle-treated cells, P < .05) and had no effect on cell viability. On the basis of T2 relaxation times, the in vitro MR detection limit of 58 labeled monocytes per 0.05 microL was calculated. Migration of labeled monocytes was not different from that of vehicle-treated cells. Intracellular iron had no effect on production of IL-1 and IL-6 24 hours after labeling. CONCLUSION:In vitro labeling of human monocytes is effective by using SPIOs, not USPIOs. Incubation with SPIOs (1.0 mg Fe/mL) results in efficient labeling detectable on MR images and does not affect cellular viability and activation markers such as cell migration and cytokine production.

背景与目标：

BACKGROUND & AIMS: MRI of superparamagnetic iron oxide (SPIO)-labeled cells has become a valuable tool for studying the in vivo trafficking of transplanted cells. Cellular detection with MRI is generally considered to be orders of magnitude less sensitive than other techniques, such as positron emission tomography (PET), single photon emission-computed tomography (SPECT), or optical fluorescence microscopy. However, an analytic description of the detection threshold for single SPIO-labeled cells and the parameters that govern detection has not been adequately provided. In the present work, the detection threshold for single SPIO-labeled cells and the effect of resolution and SNR were studied for a balanced steady-state free precession (SSFP) sequence (3D-FIESTA). Based on the results from both theoretical and experimental analyses, an expression that predicts the minimum detectable mass of SPIO (m(c)) required to detect a single cell against a uniform signal background was derivedm(c) = 5v/(K(fsl) x SNR), where v is the voxel volume, SNR is the image signal-to-noise ratio, and K(fsl) is an empirical constant measured to be 6.2 +/- 0.5 x 10(-5) microl/pgFe. Using this expression, it was shown that the sensitivity of MRI is not very different from that of PET, requiring femtomole quantities of SPIO iron for detection under typical micro-imaging conditions (100 microm isotropic resolution, SNR = 60). The results of this work will aid in the design of cellular imaging experiments by defining the lower limit of SPIO labeling required for single cell detection at any given resolution and SNR.

背景与目标： 超顺磁性氧化铁 (SPIO) 标记细胞的MRI已成为研究移植细胞体内运输的有价值的工具。MRI的细胞检测通常被认为比其他技术 (例如正电子发射断层扫描 (PET)，单光子发射计算机断层扫描 (SPECT) 或光学荧光显微镜) 的敏感性低几个数量级。但是，尚未充分提供单个SPIO标记细胞的检测阈值和控制检测的参数的分析描述。在当前工作中，研究了平衡稳态自由进动 (SSFP) 序列 (3D-FIESTA) 的单个SPIO标记细胞的检测阈值以及分辨率和SNR的影响。根据理论和实验分析的结果，可以预测在均匀信号背景下检测单个细胞所需的SPIO (m(c)) 的最小可检测质量的表达式为dm(c) = 5v/(K(fsl) x SNR)，其中v是体素体积，SNR是图像信噪比，K(fsl) 是测量为6.2 +/- 0.5 × 10(-5) microl/pgFe的经验常数。使用该表达式，表明MRI的灵敏度与PET的灵敏度没有太大差异，需要在典型的微成像条件下 (100微m各向同性分辨率，SNR = 60) 检测SPIO铁的飞度量。这项工作的结果将通过定义在任何给定分辨率和SNR下进行单细胞检测所需的SPIO标记的下限来帮助细胞成像实验的设计。

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：