超顺磁性氧化铁在肝脏局灶性病变中的定性研究

目的 探讨超顺磁性氧化铁（SPIO）增强MRI在肝脏局灶性病变的定性能力。材料与方法 43例怀疑肝占位者经常规MRI和Gd-DTPA增强后1－7后,行SPIO增强检查。其中31例经手术病理证实,12例经随访、实验室生化检查及临床资料证实。分析平扫MRI及SPIO增强后病灶的信号变化,并与Gd-DTPA动态增强结果相对照。结果 43例共12种病变、单发病灶21例,多病灶22例。包括原发性肝细胞肝癌22例,血管瘤5例,囊肿4例,转移性肝癌5例,肝硬化结节4例,局灶性结节增生（FNH）5例,其他病变6例。22例多发病灶中有8例合并1或2种病变。SPIO增强后,肝细胞肝癌T1WI为等或略高信号,T2WI为较高信号;血管瘤T1WI为较高信号,T2WI信号同平扫为高信号;囊肿T1WI、T2WI信号无改变;肝硬化结节T2WI为等信号同正常肝实质;FNH T2WI信号明显下降。其余病变的诊断SPIO增强不具有特征性,须与Gd-DTPA动态增强相结合。结论 SPIO具有一定的定性能力Gd-DTPA增强相结合,可帮助提高肝局灶性病变诊断和鉴别诊断的准确性。     

Focal nodular hyperplasia: lesion characteristics on state-of-the-art MRI including dynamic gadolinium-enhanced and superparamagnetic iron-oxide-uptake sequences in a prospective study

PURPOSE: To image a cohort of patients with pathology-proven focal nodular hyperplasia (FNH) to assess which characteristics of state-of-the-art magnetic resonance imaging (MRI) of the liver are the most useful for improving the detection and characterization of FNH. MATERIALS AND METHODS: In 14 patients, pathology-proven FNH (N=33) were prospectively examined using gadolinium (Gd) and superparamagnetic iron-oxide (SPIO) contrast media. All lesions were evaluated for signal intensity (SI), fatty infiltration, central scar, mode of enhancement with Gd, and uptake of SPIO. The percentage of dynamic contrast enhancement in the arterial, portal, and delayed phases was assessed. The contrast-to-noise ratio (CNR) before and after administration of SPIO contrast was calculated. RESULTS: The SI of the lesions was low to isointense on T1-weighted (T1W) images, and intermediate to isointense on T2W images. Fatty infiltration of the lesions was present in 6%. The percentages of enhancement in the liver and lesion were 110%, 115%, and 95%, and 151%, 182%, and 160%, respectively (P<0.0001). All lesions showed uptake of SPIO with improved conspicuity of the central scar and septa. The CNR values precontrast and post-Gd/SPIO were significantly different for T1 in- and opposed-phase and black-blood echo-planar imaging (BBEPI). CONCLUSION: Combining dynamic Gd-enhanced imaging with T1W and T2W sequences after administration of SPIO facilitates comprehensive evaluation of FNH.     

钆塞酸二钠增强MRI肝胆期高信号病变影像表现与特征分析

目的 探讨钆塞酸二钠（Gd-EOB-DTPA）增强MRI肝胆期高信号病变的影像学特征并进行分型。方法 回顾性纳入经手术病理或典型影像表现及临床随访证实为肝脏局灶性病变的病人124例,平均年龄（55.1±15.8）岁。分析肝脏局灶性病变124个,包括肝细胞癌（HCC）52个、胆管细胞癌（ICC）7个、混合型肝细胞癌-胆管癌（cHCC-CC）4个、转移瘤（HM）6个、局灶性结节增生（FNH）及FNH样变42个、肝腺瘤（HCA）2个、异型增生结节（DN）5个、肝海绵状血管瘤（CHL）6个。所有病人均行肝脏Gd-EOB-DTPA增强MRI检查,观察分析肝胆期高信号病变特征并对其进行分型。同一病变中不同分型间占比的比较采用Fisher确切概率检验。计算肝胆期病灶-肝脏信号强度比（LLR）,不同病变间LLR的比较采用Kruskal-Wallis检验。结果 HCC、ICC、HM、FNH/FNH样变和DN病变中不同分型间占比的差异均有统计学意义（均P<0.05）。HCC病灶中28个可见包膜（53.85%）,各分型中Ⅱb型最多（23/52,44.23%）;ICC病灶中Ⅱa型和Ⅲ型最多（均为3/7,...     

In vivo magnetic resonance imaging of iron oxide-labeled, arterially-injected mesenchymal stem cells in kidneys of rats with acute ischemic kidney injury: detection and monitoring at 3T

PURPOSE: To evaluate MRI for a qualitative and quantitative in vivo tracking of intraaortal injected iron oxide-labeled mesenchymal stem cells (MSC) into rats with acute kidney injury (AKI). MATERIALS AND METHODS: In vitro MRI and R2* measurement of nonlabeled and superparamagnetic iron oxide (SPIO)-labeled MSC (MSC(SPIO)) was performed in correlation to cellular iron content and cytological examination (Prussian blue, electron microscopy). In vivo MRI and R2* evaluation were performed before and after ischemic/reperfusion AKI (N = 14) and intraaortal injection of 1.5 x 10(6) MSC(SPIO) (N = 7), fetal calf serum (FCS) (medium, N = 6), and SPIO alone (N = 1) up to 14 days using a clinical 3T scanner. Signal to noise ratios (SNR), R2* of kidneys, liver, spleen, and bone marrow, renal function (creatinine [CREA], blood urea nitrogen [BUN]), and kidney volume were measured and tested for statistical significance (Student's t-test, P < 0.05) in comparison histology (hematoxylin and eosin [H&E], Prussian blue, periodic acid-Schiff [PAS], CD68). RESULTS: In vitro, MSC(SPIO) showed a reduction of SNR and T2* with R2* approximately number of MSC(SPIO) (R2 = 0.98). In vivo MSC(SPIO) administration resulted in a SNR decrease (35 +/- 15%) and R2* increase (101 +/- 18.3%) in renal cortex caused by MSC(SPIO) accumulation in contrast to control animals (P < 0.01). Liver, spleen, and bone marrow (MSC(SPIO)) showed a delayed SNR decline/R2* increase (P < 0.05) resulting from MSC(SPIO) migration. The increase of kidney volume and the decrease in renal function (P < 0.05) was reduced in MSC-treated animals. CONCLUSION: Qualitative and quantitative in vivo cell-tracking and monitoring of organ distribution of intraaortal injected MSC(SPIO) in AKI is feasible in MRI at 3T.     

Differentiation of well‐differentiated hepatocellular carcinomas from other hepatocellular nodules in cirrhotic liver: Value of SPIO‐enhanced MR imaging at 3.0 Tesla

Purpose

To determine the diagnostic value of superparamagnetic iron oxide (SPIO)‐enhanced MRI for the differentiation of well‐differentiated hepatocellular carcinomas (WD‐HCCs) from other hepatocellular nodules in cirrhotic liver.

Materials and Methods

This study included 114 patients with 216 histologically confirmed hepatocellular nodules, i.e., 23 dysplastic nodules (DNs), 37 WD‐HCCs, and 156 moderately or poorly differentiated HCCs (MD‐/PD HCCs), who underwent SPIO‐enhanced MRI at 3.0T. MRI included T2‐weighted fast‐spin echo and T2*‐weighted gradient recalled echo (GRE) sequences before and after administration of ferucarbotran. The contrast‐to‐noise ratio (CNR) of the lesion was calculated. Reviewers analyzed signal intensity (SI) of the nodules and their enhancement features on SPIO‐enhanced images. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy in the diagnosis of WD‐HCC were also calculated.

Results

The mean CNR of WD‐HCC was significantly higher than that of DN on T2*‐weighted image. Incomplete high SI on SPIO‐enhanced T2*‐weighted images were seen in 56.8% of WD‐HCC. The most prevalent enhancement features of WD‐HCCs on SPIO‐enhanced T2*‐weighted images, were iso SI with high SI foci [32.5% (12/37)] and homogenous subtle high SI [24.3% (9/37)]. Alternatively, 22 of 23 DNs (95.7%) showed low‐ or iso SI, and 145 of 156 (94.9%) MD‐/PD HCCs showed strong high SI. When iso SI with high SI foci or subtle homogenous high SI nodule was considered as diagnostic criteria for WD‐HCC, we could identify 56.8% of the WD‐HCCs but only 4.4% of the DNs and 3.2% of the MD‐/PD HCCs.

Conclusion

WD‐HCCs have characteristic enhancement features that differentiate them from DNs and MD‐/PD HCCs on SPIO‐enhanced 3.0T MRI. The lesion conspicuity was better on T2*‐weighted images than that on T2‐weighted images. J. Magn. Reson. Imaging 2009;29:328–335. © 2009 Wiley‐Liss, Inc.     

Assessment of sequential enhancement patterns of focal nodular hyperplasia and hepatocellular carcinoma on mangafodipir trisodium enhanced MR imaging

RATIONALE AND OBJECTIVES: Sequential contrast changes of mangafodipir trisodium (Mn-DPDP)-enhanced magnetic resonance imaging (MRI) were evaluated in the differentiation of focal nodular hyperplasias (FNH) and hepatocellular carcinomas (HCC). METHODS: Patients with FNH (n = 16) or HCC (n = 12) underwent MRI: T2-weighted fast spin echo before and T1-weighted gradient echo before and 1, 4, 14, and 22 hours after 5 micromol/kg Mn-DPDP. Homogeneity of enhancement and delineation of fibrous scars of FNHs were assessed qualitatively. Lesion-to-liver contrast changes of FNHs and HCCs were compared quantitatively (Mann-Whitney U). RESULTS: Mn-DPDP improved detection of characteristic scars of FNHs from 50% before to 90% after contrast agent. Apart from fibrous tissue enhancement of FNHs was mostly homogeneous (90%). Time-dependent contrast changes were up to 20 times higher (after 4 hours) for FNHs than HCCs (P < 0.0001). CONCLUSIONS: Mn-DPDP-enhanced MRI helps to delineate characteristic morphologic features of FNHs and can provide quantitative data differentiating FNH and HCC.     

菲立磁增强MRI检测肝脏占位病变与三期动态增强CT扫描的比较研究

目的　比较菲立磁增强MRI和增强CT扫描在肝脏实性占位病变检测中的应用价值。方法　对 18例肝内局灶性占位患者行MR平扫及菲立磁增强扫描。观察肝脏与病灶信号强度变化 ,形态及数目 ,比较增强前后T2 WI病灶及肝脏的信噪比 (SNR)及对比噪声比 (CNR) ,做出MRI定性诊断 ,并与增强CT扫描诊断进行比较。其中肝细胞肝癌 4例 ,复发性肝癌 4例 ,转移瘤 4例 ,肝血管瘤 6例。结果　菲立磁增强明显降低正常肝组织信号强度 ,而恶性肿瘤的信号强度无强化 ,病灶—肝脏信噪比增加可清晰显示病变 ,并发现新病灶。肝血管瘤的血池效应与增强CT扫描比较有鉴别诊断意义。结论　做为增强CT扫描和Gd -DTPAMR增强的补充方法 ,SPIO增强MRI对肝脏占位病变的显示 ,小病灶发现和定性诊断中有重要的临床意义     

Comparison of various techniques of iron oxide-enhanced breath-hold MR imaging of hepatocellular carcinoma

The purpose of our study is to compare qualitatively and quantitatively the abilities of various superparamagnetic iron oxide (SPIO)-enhanced breath-hold magnetic resonance imaging (MRI) techniques to detect hepatocellular carcinoma (HCC). Eight patients with HCCs were imaged. The images were obtained with conventional T2-weighted spin-echo imaging (CSE), half-Fourier single-shot turbo spin-echo (HASTE), single-shot gradient-echo type echo planar imaging (GE-EPI), and single-shot spin-echo type echo planar imaging (SE-EPI) before and after SPIO administration. The liver signal-to-noise ratios (SNRs) in CSE and each EPI sequence were significantly decreased after SPIO administration. GE-EPI had the highest decrease ratio (DR) of liver SNR, followed by SE-EPI (TE=98), SE-EPI (TE=28), CSE, and HASTE in this order. The relative contrasts with GE-EPI and SE-EPI (TE=98) were significantly higher than that with CSE after SPIO administration. On receiver operating characteristic (ROC) analysis, diagnostic accuracy did not differ significantly among the pulse sequences after SPIO administration. GE-EPI and SE-EPI (longer TE) were useful for SPIO-enhanced breath-hold MRI performed to detect HCC.     

MRI in focal liver disease: A comparison of small and ultra-small superparamagnetic iron oxide as hepatic contrast agents

The purpose of this study was to compare small and ultrasmall superparamagnetic iron oxide particles (SPIO and USPIO, respectively) as MR contrast agents for the evaluation of focal hepatic disease. In two different patient groups (SPIO [n = 53], USPIO [n = 27]), with focal liver disease (metastases, hepatocellular carcinoma [HCC], hepatocellular adenoma [HCA], and focal nodular hyperplasia [FNH]), spin-echo T1- and T2-weighted images (T1WI, T2WI) were obtained at 1.0T, before and after intravenous contrast administration. The percentage signal-to-noise ratio (SNR) change and lesion-to-liver contrast (LLC) were measured and statistically compared. The liver decreased in signal intensity (SI) after SPIO administration (?28%) and increased after USPIO administration (+16%) on T1WI. On T2WI, the liver decreased in SI on postcontrast images with both agents (?78% SPIO, ?73% USPIO). This difference was not statistically significantly different (P ? .07). Both SPIO and USPIO provided >500% improvement in LLC on T2WI. On T1WI, LLC was increased in metastases (120%) and HCC (325%) with SPIO. Post-USPIO, LLC was increased on T1WI only in metastases (>500%). Both SPIO and USPIO show excellent hepatic uptake, presumed secondary to reticuloendothelial activity, based on the degree of %SI change seen in the liver after administration of contrast on T2WI. However, USPIO preparations exhibit blood pool activity that may aid in further characterization of focal liver lesions, as is evidenced by their greater T1 effect in the liver and in some focal liver lesions.     

MRI对比噪声比对肝占位性病变微血管评估的价值

目的:研究肝良恶性病变微血管密度(MVD)与动态增强MRI对比噪声比(CNR)之间的联系,以建立通过MRl评估微血管分布的理论基础,为临床诊断治疗HCC提供依据.方法:115例肝细胞癌(HCC),6例肝细胞胆管细胞混合癌,14例胆管细胞癌,3例局灶性结节增生(FNH),2例肝腺瘤,4例坏死肝癌,3例慢性肝脓肿,3例凝固坏死,4例腺瘤样增生,2例血管平滑肌脂肪瘤,6例炎性假瘤,1例纤维炎性坏死结节,1例嗜酸性肉芽肿及1例神经纤维瘤.MRI检查后手术切除全部病灶,切除标本经CD34单克隆抗体免疫组化染色,计数MVD.测量痛灶信号强度SI灶,肝实质信号强度SI肝和背景噪声信号强度SI噪,分别计算各时相CNR=(SI灶-SI肝)/SI噪.按病灶直径＜3cm,＞3cm分组分别计算动态增强各时相病灶的对比噪声比(CNR),按病理诊断分组分别对动脉期、门脉期和平衡期CNR与病灶MVD计数行Pearson相关分析.HCC组按病灶最大径＜3cm和＞3cm分为两组.结果:两组HCC各时相CNR与MVD计数均有显著相关性(P＜0.05),但其余病变未显示明显相关.结论:MRI对比噪声比可用于评估HCC微血管密度,动态增强MRI对于显示HCC病灶具有重要作用.     

不同MR扫描序列在SPIO增强大鼠肝癌模型的对比研究

目的：比较多种扫描序列超顺磁氧化铁（SPIO）增强扫描对显示大鼠肝癌病灶的能力，找出最佳扫描方案。TSE T2WI、SE双回波的T2WI＋PDWI、GRE T1WI、T2^＊WI，分析增强前后大鼠肝癌病灶的强化特征，并进行病理学检查对照分析。结果：注射SPIO对比剂后，所有扫描序列均显示肝脏的信号强度较增强前有不同程度的下降，肝癌病灶CNR均分别高于平扫。增强后GRE T2^＊WI中病灶的CNR明显高于其它序列，但增强后TSE T2WI和常规SE T2WI在显示病变的SNR、CNR方面没有显著性差异。结论：SPIO增强后检测肝癌病灶的各种序列中，以GRE T2^*WI最为敏感，其次是双回波的T2WI＋PDWI序列。     

Evaluation of optimized inversion-recovery fat-suppression techniques for T2-weighted abdominal MR imaging

PURPOSE: To test the theoretical benefits of a spectral attenuated inversion-recovery (SPAIR) fat-suppression (FS) technique in clinical abdominal MRI by comparison to conventional inversion-recovery (IR) FS combined with T2-weighted (T2W) partial Fourier single shot fast spin echo (SSFSE). MATERIALS AND METHODS: 1.5T MRI studies of the abdomen were performed in 28 patients with liver lesions (hemangiomas n = 14; metastases n = 14). T2W sequences were acquired using IR and SPAIR SSFSE. Measurements included retroperitoneal and mesenteric fat signal-to-noise (SNR) to evaluate FS; liver lesion contrast-to-noise (CNR) to evaluate bulk water signal recovery effects; and bowel wall delineation to evaluate susceptibility and physiological motion effects. RESULTS: SPAIR-SSFSE images produce significantly improved FS and liver lesion CNR. The mean SNR of the retroperitoneal and mesenteric fat for SPAIR SSFSE was 20.5 +/- 10.2 (+/-1 SD) and 12.7 +/- 6.2, compared to 43.2 +/- 24.1 (P = 0.000006) and 29.3 +/- 16.8 (P = 0.0000005) for IR-SSFSE. SPAIR-SSFSE images produced higher CNR for both hemangiomas CNR = 164 +/- 88 vs. 126 +/- 83 (P = 0.00005) and metastases CNR = 75 +/- 27 vs. 53 +/- 19 (P = 0.007). Bowel wall visualization was significantly improved using SPAIR-SSFSE (P = 0.002). CONCLUSION: The theoretical benefits of SPAIR over conventional IR FS translate into significant multiple improvements that can be measured on clinical abdominal MRI scans.     

The value of gadobenate dimeglumine-enhanced delayed phase MR imaging for characterization of hepatocellular nodules in the cirrhotic liver

OBJECTIVES: To evaluate the value of 1-hour delayed phase imaging (DPI) of gadobenate dimeglumine (Gd-BOPTA)-enhanced MR imaging for the characterization of hepatocellular carcinoma (HCC) and dysplastic nodule (DN) in patients with cirrhosis. MATERIALS AND METHODS: A total of 37 patients with 42 HCCs and 13 DNs were included in this study and all lesions were histopathologically confirmed except for 15 HCCs. T1-weighted 3-dimensional gradient-echo images were acquired before, immediately after (30, 60, 180 s), and 1 hour after bolus injection of gadobenate dimeglumine at a dose of 0.1 mmol/kg. The lesions were classified as isointense, hypointense, or hyperintense compared with the surrounding liver parenchyma on DPI for qualitative assessment. We performed quantitative analyses of the contrast-to-noise ratio (CNR) and of the relative contrast enhancement of the lesion on the DPI. RESULTS: In the qualitative analysis, among 42 HCCs, 30 (71.4%) were hypointense on DPI, and 10 (23.8%) and 2 (4.8%) were isointense and hyperintense, respectively; only 1 of 13 DNs (7.7%) was hypointense and 10 (76.9%) and 2 (15.4%) were isointense and hyperintense, respectively. In contrast, 25 HCCs (71.4%) of 35 hypervascular HCCs were hypointense on DPI, and no hypervascular DN (0/7) was hypointense with statistical significance (P = 0.0007). When we considered the hypointensity of the hepatic lesions on delayed phase as a sign of HCC in cirrhotic liver, our results gave a sensitivity of 71.4% and a specificity of 91.7%. In the quantitative analysis, the mean CNR of the HCCs and the DNs on the 1-hour DPI was -6.32 +/- 6.27 and -0.07 +/- 3.28, respectively; the difference between the HCCs and the DNs was significant (P < 0.05). CONCLUSIONS: Delayed gadobenate dimeglumine-enhanced MR imaging allows improved characterization of HCC in cirrhotic liver. The relative hypointensity to adjacent normal liver parenchyma is a reliable predictor that this lesion favors HCC rather than DN in cirrhotic liver.     

Conspicuity of zones of ablation after radiofrequency ablation in porcine livers: comparison of an extracellular and an SPIO contrast agent

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.     

Hepatocellular carcinoma with marginal superparamagnetic iron oxide uptake on T2*-weighted magnetic resonance imaging: histopathologic correlation

Purpose

To evaluate the characteristics of hepatocellular carcinomas (HCCs) with marginal superparamagnetic iron oxide (SPIO) uptake on T2*-weighted MRI.

Materials and methods

The study group consisted of 73 patients with 83 surgically resected HCCs. Preoperative SPIO-enhanced MRI studies were retrospectively reviewed. Marginal SPIO uptake was considered positive if a rim-like or band-like low intensity area was present on SPIO-enhanced T2*-weighted images. The prevalence of marginal SPIO uptake was evaluated. Pathological specimens with hematoxylin and eosin staining and immunohistochemical staining of CD68 were reviewed in HCCs with marginal SPIO uptake and 33 HCCs without marginal SPIO uptake (control group).

Results

Ten of 83 (12%) HCCs showed marginal SPIO uptake. All HCCs were hypervascular, and only one nodule showed a nodule-in-nodule appearance on imaging findings. The pathology specimens suggested possible causes of marginal SPIO uptake, including marginal macrophage infiltration in moderately or poorly differentiated HCC (n = 4), residual normal hepatic tissue at the marginal area of confluent multinodular or single nodular with extranodular growth type HCC (n = 3), and a well-differentiated HCC component in nodule-in-nodule type HCC (n = 3). Marginal macrophage infiltration was not seen in the control group.

Conclusion

SPIO-enhanced MRI may be able to demonstrate marginal macrophage infiltration in HCC.     

Detection of hepatocellular carcinoma (HCC) using super paramagnetic iron oxide (SPIO)‐enhanced MRI: Added value of diffusion‐weighted imaging (DWI)

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. J. Magn. Reson. Imaging 2010; 31: 373–382. © 2010 Wiley‐Liss, Inc.     

超顺磁性氧化铁在大鼠诱癌模型磁共振诊断与鉴别诊断中的作用

目的研究超顺磁性氧化铁(SPIO)在大鼠诱癌模型的磁共振成像中对增生性结节与肝癌的鉴别作用，以及SPIO增强前后对各型肝癌的检出率。材料与方法42只诱发型肝癌模型鼠在肝硬化多发增生性结节基础上，共计生成379个肝癌，行平扫及SPIO增强扫描，分析增生性结节与肝癌的不同强化方式，并与病理对照统计平扫与增强扫描各型肝癌的检出率。结果增生性结节在SPIO增强扫描T2WI上信号明显降低，而肝癌的信号无明显改变；肝癌SPIO增强扫描T2WI检出率与病理接近，而平扫T2WI检出率与病理相差显著，其中平扫微癌与小癌的漏检率分别达32．9％与12．9％。结论SPIO是一种有效的检测肝癌的磁共振对比剂，不仅能提高小肝癌的检出率而且对增生性结节与肝癌的鉴别提供帮助。     

Higher lesion conspicuity for SENSE dynamic MRI in detecting hypervascular hepatocellular carcinoma: analysis through the measurements of liver SNR and lesion–liver CNR comparison with conventional dynamic MRI

The aim of our study was to compare the signal-to-noise ratio (SNR) of liver parenchyma and the contrast-to-noise ratio (CNR) of hypervascular hepatocellular carcinoma (HCC) between conventional and SENSE dynamic MRI. Thirty-one consecutive patients who were strongly suspected of having HCC were enrolled in our study. The subjects consisted of 20 men and 11 women aged 52 years to 79 years (mean 66.8 years). Dynamic MRI was performed for each patient, with SENSE (SENSE MRI) and without SENSE (conventional MRI) on separate days. For the quantitative analysis, the liver SNR and the lesion–liver CNR of 25 hypervascular HCCs detected on both conventional and SENSE dynamic MRI were measured. The liver SNR of the arterial phase and the portal venous phase was 84.1±24.7 and 104.7±34.3, respectively, in conventional MRI, while it was 62.9±19.5 and 44.5±18.2, respectively, in SENSE MRI. SENSE MRI showed a statistically significantly lower SNR than conventional MRI (P<0.01). The lesion–liver CNR was 26.3±15.9 in conventional MRI and 39.0±19.6 in SENSE MRI. The lesion–liver CNR in SENSE MRI was significantly higher than in conventional MRI (P<0.01). The SNR in SENSE MRI is significantly lower than in conventional MRI, although the lesion CNR is significantly higher than in conventional MRI.     

Novel double contrast MRI technique for intramyocardial detection of percutaneously transplanted autologous cells.

Bone marrow cells (BMC) labeled with iron particles can be injected into the heart and detected with MRI. Improvement in conspicuity of labelled cells would be advantageous. This study examined if double contrast with iron oxide and Gd-DTPA enhances cell MRI after transvascular transplantation in myocardial infarction. Ten pigs with week-old myocardial infarction had transvascular peri-infarct delivery of microspheres alone (Group I, n = 3) or mixed with iron-labeled BMCs (Group II, n = 7). Gradient-echo MRI before and 1 min after systemic Gd-DTPA administration produced regions of interest with hypoenhancement that were compared to contralateral regions for contrast-to-noise (CNR) and signal-to-noise (SNR) ratios. All hearts were harvested for gross and microscopic analysis. Areas of focal hypoenhancement corresponding to the BMCs were detected in the myocardium in Group II. Early after administration of Gd-DTPA CNR increased from 17.58 +/- 8.5 to 27.25 +/- 15.8 (P < 0.05) and SNR from 24.87 +/- 9.6 to 35.08 +/- 15.5 (P < 0.05). There was no hypoenhancement in Group I. Tissue examination confirmed presence of iron-containing cells and microspheres in corresponding segments of the heart. The distribution of microspheres was similar between the groups. Double contrast with cellular iron and Gd-DTPA in surrounding myocardium resulted in improved cell localization by MRI.     

Assessment of myocardial viability using delayed enhancement magnetic resonance imaging at 3.0 Tesla

OBJECTIVE: Cardiac magnetic resonance imaging (MRI) at 3.0 T has recently become available and potentially provides a significant improvement of tissue contrast in T1-weighted imaging techniques relying on Gd-based contrast enhancement. Imaging at high-field strength may be especially advantageous for methods relying on strong T1-weighting and imaging after contrast material administration. The aim of this study was to compare cardiac delayed enhancement (DE) MRI at 3.0 T and 1.5 T with respect to image quality, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) between infarcted and normal myocardium. MATERIALS AND METHODS: Forty consecutive patients with history of myocardial infarction were examined at 3.0 T (n = 20) or at 1.5 T (n = 20). Myocardial function was assessed using cine steady-state-free-precession (SSFP) sequences (TR 3.1 milliseconds, TE 1.6 milliseconds, flip angle 70 degrees , and a matrix of 168 x 256 at 1.5 T and TR 3.4 milliseconds, TE 1.7 milliseconds, flip angle 50 degrees and a matrix of 168 x 256 at 3.0 T), acquired in long- and short-axes views. DE images were obtained 15 minutes after the administration of 0.15 mmol of Gd-DTPA/kg body weight using a segmented inversion recovery prepared gradient echo sequence at 1.5 T (TR 9.6 milliseconds, TE 4.4 milliseconds, flip angle 25 degrees , matrix 160 x 256, bandwidth 140 Hertz/pixel) and at 3.0 T (TR 9.8 milliseconds, TE 4.3 milliseconds, flip angle 30 degrees , matrix 150 x 256, bandwidth 140 Hertz/pixel). For image analysis, standardized SNR and CNR measurements were performed in infarcted and remote myocardial regions. Two independent observers rated image quality on a 4-point scale (0 = poor image quality, 1 = sufficient image quality, 2 = good image quality, 3 = excellent image quality). RESULTS: High diagnostic image quality was obtained in all patients. Rating of mean image quality was 2.2 +/- 0.8 at 1.5 T and 2.5 +/- 0.6 at 3.0 T (P = 0.012) for observer 1 and 2.2 +/- 0.7 at 1.5 T and 2.6 +/- 0.6 at 3.0 T (P = 0.003) for observer 2, respectively. Interobserver agreement was good (kappa = 0.68 at 1.5 T and 0.78 at 3.0 T). SNR measurements yielded a mean SNR of 37.8 +/- 13.9/22.9 +/- 6.0 in infarcted myocardium (P < 0.001) and 5.6 +/- 2.2/5.9 +/- 2.4 in normal myocardium (P = 0.45) at 3.0 T/1.5 T, respectively. CNR measurements revealed mean values of 32.4 +/- 13.0/16.7 +/- 5.4 (P< 0.001) at 3.0 T/1.5 T, respectively. CONCLUSIONS: Delayed enhancement MRI at 3.0 T is feasible and provides superior image quality compared with 1.5 T. Furthermore, using identical contrast doses, increased SNR and CNR values were recorded at 3.0 T.