Optical imaging of matrix metalloproteinase-2 activity in tumors: feasibility study in a mouse model.

PURPOSE: To develop an optical imaging method to determine the expression level of tumoral matrix metalloproteinase-2 (MMP-2) in vivo. MATERIALS AND METHODS: An optical contrast agent was developed that was highly activatable by means of MMP-2-induced conversion. Signal characteristics of the probe were quantified ex vivo with a recombinant enzyme. Animal tumor models were established with MMP-2-positive (human fibrosarcoma cell line, n = 4) and MMP-2-negative (well-differentiated mammary adenocarcinoma, n = 4) tumor cell lines. Both tumors were implanted into nude mice and were optically imaged after intravenous administration of the MMP-2-sensitive probe. RESULTS: The MMP-2-sensitive probe was activated by MMP-2 in vitro, producing up to an 850% increase in near-infrared fluorescent signal intensity. This activation could be blocked by MMP-2 inhibitors. MMP-2-positive tumors were easily identified as high-signal-intensity regions as early as 1 hour after intravenous injection of the MMP-2 probe, while contralateral MMP-2-negative tumors showed little to no signal intensity. A nonspecific control probe showed little to no activation in MMP-2-positive tumors. CONCLUSION: It is feasible to image MMP-2 enzyme activity in vivo by using near-infrared optical imaging technology and "smart" matrix metalloproteinase-sensitive probes.     

Transarterial Delivery of a Biodegradable Single-Agent Theranostic Nanoprobe for Liver Tumor Imaging and Combinatorial Phototherapy

PurposeTo assess selective accumulation of biodegradable nanoparticles within hepatic tumors after transarterial delivery for in vivo localization and combinatorial phototherapy.Materials and MethodsA VX2 hepatic tumor model was used in New Zealand white rabbits. Transarterial delivery of silicon naphthalocyanine biodegradable nanoparticles was performed using a microcatheter via the proper hepatic artery. Tumors were exposed via laparotomy, and nanoparticles were observed by near-infrared (NIR) fluorescence imaging. For phototherapy, a handheld NIR laser (785 nm) at 0.6 W/cm² was used to expose tumor or background liver, and tissue temperatures were assessed with a fiberoptic temperature probe. Intratumoral reactive oxygen species formation was assessed using a fluorophore (2′,7′-dichlorodihydrofluorescein diacetate).ResultsNanoparticles selectively accumulated within viable tumor by NIR fluorescence. Necrotic portions of tumor did not accumulate nanoparticles, consistent with a vascular distribution. NIR-dependent heat generation was observed with nanoparticle-containing tumors, but not in background liver. No heat was generated in the absence of NIR laser light. Reactive oxygen species were formed in nanoparticle-containing tumors exposed to NIR laser light, but not in background liver treated with NIR laser or in tumors in the absence of NIR light.ConclusionsBiodegradable nanoparticle delivery to liver tumors from a transarterial approach enabled selective in vivo tumor imaging and combinatorial phototherapy.     

Optical imaging of lymph nodes

Optical imaging or near infrared fluorescence (NIRF) imaging using enzymatically activatable smart probes is an exiting new imaging modality that can also be used for lymph node visualization and detection. This review intends to briefly summarize general aspects of optical imaging and its capabilities for lymph node imaging.     

Quantitative real-time catheter-based fluorescence molecular imaging in mice

PURPOSE: To prospectively evaluate an optical imaging system designed to perform quantitative, intravital catheter-based imaging of fluorescent molecular probes. MATERIALS AND METHODS: This study was performed according to a protocol approved by the institutional animal care committee. A fiberoptic catheter imaging system was developed to implement a normalization algorithm for real-time quantitative near-infrared (NIR) imaging. The system was validated with in vitro imaging of fluorochrome phantoms and in vivo fluorescence measurements obtained in tumors implanted in murine abdomens (n = 7) after administration of an enzyme-activatable NIR probe. Standard analysis of variance tests were used to determine significant dissimilarities in signal from distinct fluorochrome concentrations. The clinical utility of the system was further evaluated by imaging orthotopically implanted murine colonic adenocarcinomas (n = 4). RESULTS: Raw NIR fluorescence intensities, which were measured with a fiberoptic catheter placed above wells of varying NIR fluorochrome concentration, varied markedly (>100%) with catheter position, while the corrected NIR signal was confined to a range of values within 10% of their mean for each individual fluorochrome concentration and were significantly distinct (P < .001) between relevant concentration ranges. Similar results were observed for the in vivo measurements from the abdominally implanted tumors, with raw NIR signal varying 20% from the mean and corrected NIR signal varying only 1% from the mean. The colonic studies revealed that the correction method was robust enough for use during minimally invasive imaging procedures. CONCLUSION: The authors have developed and implemented a method for quantitative real-time catheter-based fluorescence imaging that resolves NIR signal dependence on changes in catheter position.     

Optical imaging of spontaneous breast tumors using protease sensing 'smart' optical probes

OBJECTIVE: The objective of this study was to determine if spontaneous breast cancer lesions can be detected by fluorescence reflectance imaging (FRI) and fluorescence mediated tomography (FMT) using protease-sensing optical probes. MATERIALS AND METHODS: Transgenic (FVB/N-TgN (WapHRAS)69Lin Y)) mice, which spontaneously develop breast cancer, were injected intravenously with a cathepsin-sensing fluorescent imaging probe. FRI and FMT were performed 24 hours after probe injection and region of interest (ROI) analysis was performed. Magnetic resonance images were acquired for anatomic coregistration with the FMT data. Moreover, correlative immunohistochemistry and fluorescence microscopy were performed. RESULTS: All tumor nodules were clearly delineated by FRI showing an average signal intensity of 380 +/- 106 AU. Similarly, tumors were clearly detected by FMT imaging. Immunohistochemistry confirmed cathepsin-B expression of primary tumors and fluorescence microscopy revealed a strong Cy 5.5 deposition in the tissue. CONCLUSIONS: FRI and FMT using "smart" protease sensing probes permits detection of experimental spontaneous breast cancers. Because the expression levels of various proteases correlate with patient outcome, this technique may not only help to detect, but also to differentiate breast cancers noninvasively.     

Near-infrared optical imaging of protease activity for tumor detection

PURPOSE: To build and test an optical imaging system that is sensitive to near-infrared fluorescent molecular probes activated by specific enzymes in tumor tissues in mice. MATERIALS AND METHODS: The imaging system consisted of a source that delivered 610-650-nm excitation light within a lighttight chamber, a 700-nm longpass filter for selecting near-infrared fluorescence emission photons from tissues, and a charge-coupled device (CCD) for recording images. The molecular probe was a biocompatible autoquenched near-infrared fluorescent compound that was activated by tumor-associated proteases for cathepsins B and H. Imaging experiments were performed 0-72 hours after intravenous injection of the probe in nude mice that bore human breast carcinoma (BT-20). RESULTS: The imaging system had a maximal spatial resolution of 60 microns, with a field of view of 14 cm2. The detection threshold of the nonquenched near-infrared fluorescent dye was subpicomolar in the imaging phantom experiments. In tissue, 250 pmol of fluorochrome was easily detected during the 10-second image acquisition. After intravenous injection of the probe into the tumor-bearing animals, tumors as small as 1 mm became detectable because of tumor-associated enzymatic activation of the quenched compound. CONCLUSION: Tumor proteases can be used as molecular targets, allowing visualization of millimeter-sized tumors. The development of this technology, probe design, and optical imaging systems hold promise for molecular imaging, cancer detection, and evaluation of treatment.     

Rapid optical imaging of EGF receptor expression with a single-chain antibody SNAP-tag fusion protein

Purpose

The epidermal growth factor receptor (EGFR) is overexpressed in several types of cancer and its inhibition can effectively inhibit tumour progression. The purpose of this study was to design an EGFR-specific imaging probe that combines efficient tumour targeting with rapid systemic clearance to facilitate non-invasive assessment of EGFR expression.

Methods

Genetic fusion of a single-chain antibody fragment with the SNAP-tag produced a 48-kDa antibody derivative that can be covalently and site-specifically labelled with substrates containing 0 ⁶-benzylguanine. The EGFR-specific single-chain variable fragment (scFv) fusion protein 425(scFv)SNAP was labelled with the near infrared (NIR) dye BG-747, and its accumulation, specificity and kinetics were monitored using NIR fluorescence imaging in a subcutaneous pancreatic carcinoma xenograft model.

Results

The 425(scFv)SNAP fusion protein accumulates rapidly and specifically at the tumour site. Its small size allows efficient renal clearance and a high tumour to background ratio (TBR) of 33.2?±?6.3 (n?=?4) 10 h after injection. Binding of the labelled antibody was efficiently competed with a 20-fold excess of unlabelled probe, resulting in an average TBR of 6?±?1.35 (n?=?4), which is similar to that obtained with a non-tumour-specific probe (5.44?±?1.92, n?=?4). When compared with a full-length antibody against EGFR (cetuximab), 425(scFv)SNAP-747 showed significantly higher TBRs and complete clearance 72 h post-injection.

Conclusion

The 425(scFv)SNAP fusion protein combines rapid and specific targeting of EGFR-positive tumours with a versatile and robust labelling technique that facilitates the attachment of fluorophores for use in optical imaging. The same approach could be used to couple a chelating agent for use in nuclear imaging.     

Imaging of differential protease expression in breast cancers for detection of aggressive tumor phenotypes

PURPOSE: To determine if different expression levels of tumor cathepsin-B activity in well differentiated and undifferentiated breast cancers could be revealed in vivo with optical imaging. MATERIALS AND METHODS: A well differentiated human breast cancer (BT20, n = 8) and a highly invasive metastatic human breast cancer (DU4475, n = 8) were implanted orthotopically in athymic nude mice. Tumor-bearing animals were examined in vivo with near-infrared fluorescence (NIRF) imaging 24 hours after intravenous injection of an enzyme-sensing imaging probe. Immunohistochemistry, Western blotting (on cells and whole tumor samples), and correlative fluorescence microscopy were performed. RESULTS: Both types of breast cancers activated the NIRF probe so that tumors became readily detectable. However, in tumors of equal size, there was a 1.5-fold higher fluorescence signal in the highly invasive breast cancer (861 arbitrary units +/- 88) compared with the well differentiated lesion (566 arbitrary units +/- 36, P <.01). Western blotting confirmed a higher cathepsin-B protein content in the highly invasive breast cancer (DU4475) of about 1.4-fold (whole tumor samples) to 1.7-fold (cells). Immunohistochemistry and fluorescence microscopy findings confirmed the imaging findings. CONCLUSION: Cathepsin-B enzyme activity can be determined in vivo with NIRF optical imaging, while differences in tumoral expression may correlate with tumor aggressiveness.     

动脉粥样硬化斑块MRI和近红外分子影像的实验研究

目的 探讨7.0 T MRI和近红外荧光成像(NIRF)检测动脉粥样硬化(AS)斑块的可行性.方法 对14周龄ApoE-/-小鼠按高脂饮食喂养20周,建立AS模型,以正常C57BL/6小鼠作为对照.MRI实验中,5只ApoE-/-小鼠及5只C57小鼠经尾静脉注入超微超顺磁性氧化铁颗粒(USPIO)前及36 h后分别行7.0 T MRI.NIRF实验中,10只ApoE-/-小鼠和4只C57小鼠经尾静脉注入抗氧化修饰的低密度脂蛋白(oxLDL)抗体-NIR 797(抗-oxLDL-抗体-NIR 797)近红外探针,4只ApoE-/-小鼠经尾静脉注入非特异性IgG-NIR 797,另4只ApoE-/-小鼠注入PBS,24h后分别行NIRF.用SPSS17.0软件对计量数据行独立样本t检验和单因素方差分析.结果 ApoE-/-小鼠注入USPIO 36 h后,在T2WI上腹主动脉斑块信号较注射前减低,相对信号强度分别为0.70±0.04和1.28±0.06,差异有统计学意义(t =3.376,P＜O.05),信号改变率达(-56.58±4.25)％;普鲁士蓝染色证实斑块内有铁沉积.注入抗-oxLDL-抗体-NIR 797 24 h后,ApoE-/-小鼠主动脉离体NIRF示强荧光信号(SNR为42.51 ±5.24)聚集于主动脉根、主动脉弓及降主动脉起始段,而非特异性IgG-NIR 797组(19.58±3.06)、PBS组(4.19±0.82)及对照C57小鼠(2.29±1.11)仅见较弱荧光信号,与靶向探针组比较差异有统计学意义(F =25.104,P＜0.05).斑块油红O染色与NIRF阳性面积分别为(41.69 ±5.29)％和(39.45±5.35)％,两者呈线性相关(r=0.738,P＜0.05,n=8),免疫荧光证实斑块内oxLDL的表达与巨噬细胞共区域.结论 应用新型分子影像探针在7.0 T MRI和NIRF上可有效检测AS斑块,有助于鉴别高危斑块,可为AS多模式成像提供依据.     

Response of osteogenic sarcoma to neoadjuvant therapy: evaluated by 18F-FDG-PET

OBJECTIVE: The aim of this study was to evaluate the potential role of F-18-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) in assessing the chemotherapy response of osteosarcoma when compared with histologically assessed tumor necrosis. METHODS: Fifteen patients were examined with whole-body FDG-PET prior to and following neoadjuvant therapy. The maximum standard uptake value (SUV max) of tumor and tumor to background ratio (TBR) prior to and following chemotherapy was used for semiquantitative PET imaging analysis. The SUV max of prechemotherapy and post-chemotherapy was recorded as SUV1 and SUV2. TBR1 and TBR2 represented prechemotherapy and post-chemotherapy TBR. TBR was calculated by drawing an identical region of interest over the tumor and the contralateral normal limb or pelvis. Tumor necrosis was classified according to Salzer-Kuntschik's criteria. RESULTS: Eight patients with more than 90% tumor necrosis were classified as showing good responses and seven patients with less than 90% tumor necrosis as showing poor responses. SUV2/SUV1, TBR2/TBR1, and TBR2 were significantly correlated with the tumor necrosis degree (P < 0.01, P < 0.001, P < 0.001). TBR2/TBR1 were below 0.46 in all the patients with favorable responses, and higher than 0.49 in all the patients with unfavorable responses. However, it was difficult to distinguish good responses from poor responses by SUV2/SUV1. CONCLUSIONS: FDG-PET is a promising tool to assess the chemotherapy response of osteosarcoma noninvasively. The TBR was better than SUV max in evaluating the chemotherapy response in this study.     

Dual optical and nuclear imaging in human melanoma xenografts using a single targeted imaging probe

INTRODUCTION: Dual-labeled imaging agents that allow both nuclear and optical imaging after a single injection would be advantageous in certain applications. In this study, we synthesized and characterized a dual-labeled RGD (Arg-Gly-Asp) peptide and compared nuclear and optical images obtained with this agent. METHODS: 111In-DTPA-Lys(IRDye800)-c(KRGDf) composed of both the 111In chelator diethylenetriaminepentaacetic acid (DTPA) and the near-infrared (NIR) fluorescent dye IRDye800 (excitation/emission, 765/792 nm) was synthesized. The probe was characterized with regard to in vitro biological activity and in vivo pharmacokinetics and the ability to target integrin alphavbeta3. Tumors of mice injected with the dual-labeled probe were imaged both by gamma scintigraphy and NIR fluorescence optical camera. RESULTS: DTPA-Lys(IRDye800)-c(KRGDf), DTPA-Lys-c(KRGDf) and c(KRGDf) inhibited the adhesion of melanoma M21 cells to vitronectin-coated surface with the similar biological activity. Both 111In-DTPA-Lys(IRDye800)-c(KRGDf) and 111In-DTPA-Lys-c(KRGDf) had significantly higher uptakes in alphavbeta3-positive M21 melanoma than in alphavbeta3-negative M21-L melanoma at 4-48 h after their injection. Side-by-side comparison of images obtained using 111In-DTPA-Lys(IRDye800)-c(KRGDf) revealed that in living mice, both optical imaging and gamma scintigraphy enabled noninvasive detection of the bound probe to alphavbeta3-positive tumors, with optical images providing improved resolution and sensitive detection of the superficial lesions and gamma images providing sensitive detection of deeper structures. CONCLUSION: The dual-labeled imaging probe 111In-DTPA-Lys(IRDye800)-c(KRGDf) was found to specifically bind to alphavbeta3 in melanoma tumor cells. Employing both nuclear and optical imaging with a single imaging probe may facilitate translation of NIR fluorescence optical imaging into clinical applications.     

荧光成像术中导航研究进展

荧光成像技术可实时获取手术过程中血管、淋巴结以及肿瘤组织等信息,有助于发现白光条件下无法识别的微小病灶,可精准定位肿瘤部位和边界,辅助医生在术中做出更准确的决策,从而降低手术切缘阳性率。就荧光成像术中导航的发展现状、临床常用的荧光探针及特点、分子荧光探针的制备和临床应用,以及该技术的局限性和应用前景予以综述。     

纳米抗体在肿瘤分子显像中的应用

纳米抗体是一种由骆驼源的重链可变区组成的单域抗体,具有相对分子质量小、亲和力高和化学稳定性好等特性,非常适于进行肿瘤以及其他疾病的PET、SPECT显像和辅助治疗研究。纳米抗体在分子影像诊断方面的优势很可能使其成为新一代核医学显像剂。     

Al18F-NOTA-FAPI-04的自动化合成与体内显像

目的:自动化合成Al¹⁸F-1,4,7-三氮杂环壬烷-1,4,7-三乙酸(NOTA)-成纤维细胞激活蛋白抑制剂(FAPI)-04,并进行体内显像,评估其诊断肿瘤的效能。方法:利用All-in-one型自动合成模块合成Al¹⁸F-NOTA-FAPI-04,并进行质量分析;取3只正常BALB/c小鼠和3只4T1小鼠乳腺癌荷瘤小鼠进行PET/CT显像,观察体内Al¹⁸F-NOTA-FAPI-04分布情况;对1例肝细胞肝癌患者(男,51岁)进行Al¹⁸F-NOTA-FAPI-04和18F-FDG PET/CT显像,评估其对肝癌的诊断效能。结果:自动化合成Al¹⁸F-NOTA-FAPI-04的时间约为35 min,合成产率约为(25.2±1.9)%(衰减校正后,n=3),产品为无色透明溶液,pH值为7.0~7.5,其比活度为(46.11±3.07)GBq/μmol(衰减校正后,n=3),放化纯大于99.0%,室温放置6 h后放化纯仍大于98.0%。小鼠体内显像示Al¹⁸F-NOTA-FAPI-04的生理性摄取主要在胆道系统和膀胱中,且高度浓聚于肿瘤病灶区域;肝细胞肝癌患者PET/CT显像示Al¹⁸F-NOTA-FAPI-04和18F-FDG PET/CT在胸骨旁淋巴结、膈上前组淋巴结、肝门区淋巴结、胰十二指肠韧带区淋巴结、腹主动脉旁淋巴结的靶本比值(TBR)分别为4.1、8.9、5.4、4.8、2.2和1.0、2.8、5.0、2.1、1.1。结论:基于All-in-one型自动合成模块合成Al¹⁸F-NOTA-FAPI-04,合成时间较短、产率高、稳定性好,高度浓聚于病灶区域,其PET图像对比度高,诊断性能优异。     

A dendrimer-based nanosized contrast agent dual-labeled for magnetic resonance and optical fluorescence imaging to localize the sentinel lymph node in mice

PURPOSE: To preoperatively and intraoperatively localize the sentinel lymph node (SLN), a single hybrid probe for MR and near infrared (NIR) optical imaging was synthesized and tested. MATERIALS AND METHODS: A macromolecular MR/NIR optical contrast agent was synthesized based on a approximately 191 gadolinium-labeled contrast agent using generation-6 polyamidoamine dendrimer (G6), which is also labeled with 2 Cy5.5, an NIR fluorophore. After establishing the optimal dose, the agent was injected into mammary glands of 10 normal mice to examine the lymphatic drainage from the breast using a 3T clinical scanner. Immediately after the MRI scan, NIR optical imaging and image-guided surgery were performed to compare the two imaging modalities. RESULTS: To consistently identify the SLNs, we needed to inject 25 microL of 30 mM [Gd] G6-Cy5.5. All SLNs could be easily identified and resected under NIR optical imaging-guided surgery. Although external NIR optical imaging failed to identify SLNs close to the injection site due to shinethrough, MR lymphography (MRL) consistently identified all SLNs regardless of their location. CONCLUSION: We have successfully synthesized and tested a dual labeled MR/NIR optical hybrid contrast agent, G6-Cy5.5 for reoperative and intraoperative localization of SLNs.     

Response of Osteosarcoma to Chemotherapy. Evaluation with F-18 FDG-PET Scans

Objective: Positron emission tomography (PET) using fluorine-18-fluoro-2-D-deoxyglucose (FDG) is increasingly being used to evaluate and manage oncology patients. Several reports have documented its utility in diagnosis, staging, response to treatment, and tumor viability assessment. There is, however, a paucity of literature on PET scanning in patients with osteosarcoma. We report results of serial F-18 FDG-PET scans in 16 untreated patients with osteosarcoma who underwent chemotherapy prior to surgical resection of the primary tumor site.Procedure: Changes in tumor fluoro-2-D-deoxyglucose (FDG) uptake were correlated with percent tumor necrosis on histopathology. PET studies were analyzed by visual assessment of tumor uptake of FDG by 3 independent observers, calculating a tumor to normal background activity ratio (TBR) by drawing regions of interest (ROIs) around the tumor and background activity in the contralateral normal limb, and percent change in TBR values between baseline and presurgical study.Results: All patients had positive baseline scans. Baseline TBRs ranged between 2.5-8.7 and visual assessment of intensity of FDG uptake was 2-3 on a scale of 0-3. At histopathologic examination, 8 patients were classified as good responses with more than 90% tumor necrosis and 8 patients as poor responses with less than 90% necrosis. Tumor necrosis was accurately predicted on PET scan in 15/16 patients by visual assessment, 14/15 patients by final TBR value on presurgery scans, and 7/15 patients using percent change of TBR on serial scans.Conclusions: The results of this small series suggest that FDG-PET scanning is fairly accurate in evaluating the response of osteosarcoma to chemotherapy. Visual assessment and TBR are more accurate in predicting tumor necrosis than percent change in TBR on serial scans.     

Preparation and primary bioevaluation of 99mTc-labeled-1-thio-β-D-glucose as melanoma targeting agent

The development of specific radiolabeled probes towards molecular markers in vivo has gained interest as targeted imaging agents for a more accurate detection of diseases. The aim of this study was to evaluate early detection of melanoma tumor based on 1-thio-β-D-glucose (1-TG) radiolabeled with technetium-99m. 99mTc-1-TG has been synthesized and evaluated in vitro and in vivo for melanoma uptake. Tumor-cell uptake of the 99mTc complex was performed with cultured B16F1 murine melanoma cells which were also used for the in vivo studies. The methodology consisted in radiopharmaceutical synthesis followed by intravenous administration of 99mTc-1-TG in melanoma bearing mice and scintigraphic imaging. 1-thio-β-D-glucose was labeled with 99mTc under reductive conditions using SnCl2. Radiolabeling efficiency was > 96%. 99mTc-1-TG showed high melanoma uptake in vitro. This was confirmed in vivo since a significant difference of 99mTc-1- TG uptake between melanoma model and the control joint was observed. General biodistribution showed renal uptake. The scintigraphic images showed tumor selective uptake of the 1-TG labeled, in tumor-bearing mice This study indicates effective labeling of 1-thio-β-D-glucose with 99mTc that shows potential as a new type of specific probe for melanoma detection.     

Magnetic resonance imaging of small nasopharyngeal tumors

Magnetic resonance (MR) images of 9 patients with a small nasopharyngeal tumor were examined, and among them three cases were evaluated with Gd-DTPA enhancement technique. All cases showed no asymmetry of parapharyngeal space, but they presented neck lymph nodes swelling. These cases were proved malignant by surgical procedures and the blind biopsy. MR findings of levator and tensor veli palatini muscles and retropharyngeal lymph nodes were retrospectively evaluated in correlation with endoscopic examination and biopsy. In six cases among 9 patients, MR images demonstrated tumors on the lateral wall of nasopharynx. Infiltration of levator veli palatini muscle was an especially important earlier sign of nasopharyngeal tumor invasion because the levator veli palatini muscle belongs to the intrapharyngeal muscle group. Endoscopic examination could not reveal any abnormal lesion in three cases among these 6 cases. No definite signal intensity difference between tumor and pharyngeal mucosa was shown on both T1 and T2 weighted images. But the normal pharyngeal mucosa had demonstrated higher intensity than tumor with Gd-DTPA administration. So the enhanced nasopharyngeal MR imaging made the clear intensity difference between tumor and muscle tissue. It was the conclusion that MR imaging was superior to X-CT in detecting small nasopharyngeal tumor.     

肿瘤微环境靶点及相关磁共振超顺磁氧化铁分子探针研究进展

影响肿瘤生物学行为的新生血管内皮细胞、肿瘤细胞及肿瘤间质细胞上的特异性受体的显像研究是肿瘤磁共振(magnetic resonance,MR)分子影像学的重要内容。针对上述特异性靶点,合成MR特异性分子探针的研究近年来得到了广泛的关注。本文就目前已知的肿瘤细胞及其微环境中主要的生物靶点阐述其相关MR超顺磁氧化铁分子探针的研究进展。