定量动态对比增强MRI分析复杂性附件肿块:初步研究

目的评价定量动态对比增强MRI(DCE-MRI)鉴别附件良恶性肿瘤的能力。方法56例患有复杂性附件肿块的妇女于术前行MR成像,其中38例恶性和18例良性。于附件肿瘤的实性组织应用药物代谢动力学模型,从高时间分辨力DCE-MRI序列中获取微血管参数。这些参数是组织血     

Quantitative dynamic contrast-enhanced MR imaging analysis of complex adnexal masses: a preliminary study

Objective  

To evaluate the ability of quantitative dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) to differentiate malignant from benign adnexal tumours.     

Characterization of adnexal mass lesions on MR imaging

OBJECTIVE: The aim of our study was to evaluate the accuracy of MR imaging in the detection and characterization of adnexal mass lesions and to determine which imaging features are predictive of malignancy. SUBJECTS AND METHODS: We prospectively performed MR imaging in 104 patients (age range, 19-87 years; mean age, 50 years) with clinically or sonographically detected complex adnexal masses. We used a 1.5-T unit to perform T1-, T2-, and fat-suppressed T1-weighted sequences before and after IV injection of gadolinium. The adnexal lesions were examined for several features including size, shape, character (solid-cystic), vegetation, signal intensity, and enhancement. Secondary signs such as ascites, peritoneal disease, and lymphadenopathy were noted. We compared the imaging features with the surgical and pathologic findings. Multiple logistic regression analysis was performed on all MR imaging features. RESULTS: A total of 163 lesions--94 benign and 69 malignant lesions--were examined. On MR imaging, 95% (155/163) of the lesions were detected. The overall accuracy for the diagnosis of malignancy was 91%. On univariate analysis, the imaging features associated with malignancy were a solid-cystic lesion, irregularity, and vegetation on the wall and septum in a cystic lesion, the large size of the lesion, an early enhancement on dynamic contrast-enhanced MR images, and the presence of ascites, peritoneal disease, or adenopathy. On multiple logistic regression analysis, ascites and vegetation in a cystic lesion were the factors most significantly indicative of malignancy. CONCLUSION: MR imaging is highly accurate in the characterization of adnexal mass lesions, and the best predictors of malignancy are vegetation in a cystic lesion and ascites.     

Magnetic resonance imaging of cystic adnexal lesions during pregnancy

Management of cystic adnexal lesions diagnosed during pregnancy is a challenging issue for obstetricians. The range of treatment options changes from immediate surgery to close follow-up. This pictorial essay illustrates the magnetic resonance imaging findings of various cystic adnexal lesions in pregnant patients. Magnetic resonance imaging may help in better characterization of some of the cystic adnexal lesions diagnosed during pregnancy without exposing the fetus to ionizing radiation.     

Spheno-occipital synchondrosis fusion degree as a method to estimate age: a preliminary,magnetic resonance imaging study

The investigation of ossification regions in the skeletal system is a basic method for forensic age estimation. Although X-ray examination is commonly used in living subjects, magnetic resonance imaging (MRI) has gained importance because of its high resolution and its avoidance of radiation exposure. In this study, we investigated the utility of MRI in the evaluation of Spheno-occipital synchondrosis (SOS) fusion degree as a method to estimate age. The MRI findings of 1078 subjects (455 were male and 623 were female) aged 7–21 years were retrospectively evaluated according to a five-stage method. We found that SOS fusion started two years earlier in female subjects. The average age for stage 5 SOS fusion was 18.43 ± 1.84 years in male subjects and 17.78 ± 2.20 years in female subjects. Our results show that MRI in the determination of SOS fusion degree is an efficient non-invasive method to estimate age and avoids the disadvantages of radiation exposure incurred by X-ray or computed tomography examinations.     

Value of MR imaging in evaluating focal fatty infiltration of the liver: preliminary study.

Focal fatty infiltration of the liver is a well-known entity that occasionally mimics metastatic disease on ultrasonographic (US) and computed tomographic (CT) scans and requires biopsy for diagnosis. To determine if high-field-strength magnetic resonance (MR) imaging might be useful in the differential diagnosis of the lesions, the authors compared US, CT, and MR findings in three patients with biopsy-proved fatty hepatic lesions. Areas of focal fatty infiltration were hyperechoic on US scans and had low attenuation on CT scans. No mass effect of the lesions on vascular structures or liver contours was observed, particularly on contrast material-enhanced CT scans. For all three patients, MR findings suggested the correct diagnosis by demonstrating focal high signal intensity on spin-echo T1- and T2-weighted images. On the basis of these preliminary findings, it appears that focal fatty infiltration of the liver may be differentiated from metastatic disease by means of high-field-strength MR imaging.     

Targeting liver lesions for radiofrequency ablation: an experimental feasibility study using a CT-US fusion imaging system

PURPOSE: To investigate the feasibility and validity of real-time guidance using a fusion imaging system that combines ultrasound (US) and computed tomography (CT) in the targeting and subsequent radiofrequency (RF) ablation of a liver target inconspicuous on US. METHODS AND MATERIALS: The study was designed as an experimental ex vivo study in calf livers with radiopaque internal targets, inconspicuous at US, simulating a focal liver lesion. The study included 2 phases. The initial phase was to examine the feasibility of matching preprocedural volumetric CT data of the calf livers with real-time US using a commercially available multimodality fusion imaging system (Virtual Navigator System, Esaote SpA, Genoa, Italy), and to assess the accuracy of targeting using a 22 gauge cytologic needle. The second phase of the study was to validate such a technique using a 15 gauge RF multitined expandable needle (RITA Medical Systems, Mountain View, CA) and to examine the accuracy of the needle placement relative to the target. The tip of the trocar of the RF needle had to be placed 1 cm from the target and then the hooks had to be deployed to 3 cm. Unenhanced CT of the liver and multiplanar reconstructions were performed to calculate accuracy of positioning, ie, the lateral distance between the needle and the target, the distance between the tip of the trocar of the RF electrode and the target, and the lateral distance between the central tine of the RF electrode and the target. RESULTS: All calf livers underwent successful CT-US registration with a mean registration error of 3.0 +/- 0.1 mm and 2.9 +/- 0.1 mm in the initial and second phase of the study, respectively. In the initial phase an overall number of 24 insertions were performed after the US-CT guidance. The mean needle to target distance was 1.9 +/- 0.7 mm (range, 0.8-3.0 mm). In the second phase an overall number of 12 ablations were performed. The mean target-trocar distance was 10.3 +/- 2.6 mm. The mean target-central tine lateral distance was 3.9 +/- 0.7 mm (range, 2.9-5.1 mm). After the dissection of the specimen the target was found unchanged in the center of the ablation zone in all cases. CONCLUSION: Real-time registration and fusion of preprocedure CT volume images with intraprocedure US is feasible and accurate. The study was however conducted in an ideal experimental setting, without patient movements and breathing, and further studies are warranted to validate the system under clinical conditions.     

结直肠癌的MRI初步研究

目的 探讨MRI对结直肠癌检查的可行性及其价值。方法 对38例经临床拟诊为结直肠癌患者行MR检查,检查前经直肠灌水300—1000ml。分别行轴面平扫,轴面、矢状面和冠状面3个平面增强扫描及水成像。结果 38例中经手术病理证实的结直肠癌31例,5例表现为腔内局限性软组织肿块,26例表现为肠壁不规则增厚,肠腔环形狭窄环绕肠腔1周或部分,平扫T1WI上呈等信号,T2WI上30例呈略高信号,1例呈明显高信号;钆喷替酸葡甲胺(Gd—DTPA)增强扫描病灶均明显强化。5例平扫SE序列T1WI上病灶周围脂肪间隙内见斑片状低信号。增强后病变段肠壁外缘光滑12例,不光滑或有结节影向外突出19例。结直肠水成像满意的24例中显示为病变部位肠腔内不规则充盈缺损14例,10例病变远侧端呈“袖口征”及“截断征”,近侧端未显示。MRI可以正确识别31例经病理证实的结直肠癌中的30例和7例非结直肠癌中的4例,诊断的敏感度、特异度和准确度分别为96．8％、57．1％和89．5%。MRI对结直肠癌T分期的准确度为83．9％(26／31),其中对T1～2期为75．0％(9／12)、对13期为88．2％(15／17)、对T4期为100％(2／2)。结论 MRI可以从整体上显示结直肠癌的纵向和横向侵犯,可以较准确地判断肿瘤在肠壁的浸润深度,水成像最大信号强度投影(MIP)重建可部分替代钡灌肠检查,为制定临床治疗方案提供有益的指导。     

Magnetic resonance imaging of the liver: New imaging strategies for evaluating focal liver lesions

The early detection of focal liver lesions, particularly those which are malignant, is of utmost importance. The resection of liver metastases of some malignancies (including colorectal cancer) has been shown to improve the survival of patients. Exact knowledge of the number, size, and regional distribution of liver metastases is essential to determine their resectability. Almost all focal liver lesions larger than 10 mm are demonstrated with current imaging techniques but the detection of smaller focal liver lesions is still relatively poor. One of the advantages of magnetic resonance imaging (MRI) of the liver is better soft tissue contrast (compared to other radiologic modalities), which allows better detection and characterization of the focal liver lesions in question. Developments in MRI hardware and software and the availability of novel MRI contrast agents have further improved the diagnostic yield of MRI in lesion detection and characterization. Although the primary modalities for liver imaging are ultrasound and computed tomography, recent studies have suggested that MRI is the most sensitive method for detecting small liver metastatic lesions, and MRI is now considered the pre-operative standard method for diagnosis. Two recent developments in MRI sequences for the upper abdomen comprise unenhanced diffusion-weighted imaging (DWI), and keyhole-based dynamic contrast-enhanced (DCE) MRI (4D THRIVE). DWI allows improved detection (b = 10 s/mm(2)) of small (< 10 mm) focal liver lesions in particular, and is useful as a road map sequence. Also, using higher b-values, the calculation of the apparent diffusion coefficient value, true diffusion coefficient, D, and the perfusion fraction, f, has been used for the characterization of focal liver lesions. DCE 4D THRIVE enables MRI of the liver with high temporal and spatial resolution and full liver coverage. 4D THRIVE improves evaluation of focal liver lesions, providing multiple arterial and venous phases, and allows the calculation of perfusion parameters using pharmacokinetic models. 4D THRIVE has potential benefits in terms of detection, characterization and staging of focal liver lesions and in monitoring therapy.     

MR扩散加权成像评估椎体骨量状况的初步研究

目的 探讨椎体MR扩散加权成像(DWI)测量值与双能X线(DXA)、定量GT(QCT)所测骨密度的相关性.方法 152例女性志愿者分别进行以下检查:胸腰椎侧位(T4～L4)X线平片,并采用Genant半定量法对其进行评阅;腰椎(L2～L4)DXA和QCT骨密度测量;腰椎常规行MR矢状面T2 WI、T1 WI和横断面T2 WI扫描;MR常规扫描结束后采用单次激发自旋回波平面回波扩散加权序列(SS-SE-EPI DWI)[扩散敏感因子(b)=500 s/mm2]进行L2～L4椎体横断面DWI扫描,并使用GE-Functool分析软件测量相应椎体表观扩散系数(ADC值).计量资料间的相关性采用Pearson相关分析.结果 随年龄增加,椎体ADC值呈逐步降低趋势.L2～L4椎体平均ADC值(0.241×10-3 mm2/s)与相应椎体平均骨密度DXA(I.038 s/cm2)、QCT(104.2 mg/cm3)具有相关性(r值分别为0.461、0.731,P值均＜0.01).结论 DWI可在常规2腰椎MRI基础上无创性评估椎体骨髓变化状况,进而来评估骨髓的变化对于骨量状况所带来的影响.     

Immunoscintigraphic imaging of inflammatory lesions: preliminary findings and future possibilities

Mixed leukocytes separated in vivo from patients' blood and labeled with lipophilic chelates of 111In and 99mTc are now used clinically for imaging inflammatory foci in many medical centers worldwide. Recent immunological advances have prompted investigations about using radiolabeled antibodies potentially specific for human neutrophils, labeling of these blood cells in vivo, and imaging inflammatory processes in patients. Early results are encouraging, allowing abscesses to be imaged with high specificity and presenting only minimal (10% to 20%) adverse immunogenic responses. However, problems remain, including low immunospecificity and lengthy procedures for radiolabeling of antibodies. These areas are currently subjects to further research that in time will contribute to make this modality convenient, simple, and efficacious.     

局灶性脑皮质发育不良的扩散张量成像初步研究

目的 探讨DTI技术诊断局灶性脑皮质发育不良(FCD)的价值.方法 回顾性分析12例FCD患者的临床、MRI及DTI等资料.DTI经过图像后处理,获得平均扩散系数(MD)和部分各向异性分数(FA)图及彩色编码张量图,于FCD的皮质下白质区及对侧相应皮质下白质区设置椭圆形ROI,测量每个ROI的MD及FA值.病灶侧与对侧MD、FA值的比较采用配对t检验.扩散张量纤维束示踪成像(DTT)以T_2 WI图像为参照,ROI设置同DTI,以ROI中的任一点作为种子点,获得通过该ROI区域的所有白质纤维束示踪图像.结果 12例患者MR平扫均显示局灶性脑皮质增厚及灰白质界限不清,其中7例显示皮质下白质稍长T_1、稍长T_2信号,2例皮质下白质萎缩,3例皮质下白质无明显异常.DTI分析显示FCD邻近皮质下白质与对侧比较FA值明显下降(患侧0.31±0.05,对侧0.42±0.08,t=-3.995,P<0.01),MD值明显上升[患侧(1.02±0.16)×10~(-3)mm~2/s,对侧(0.86±0.13)×10~(-3) mm~2/s,t=2.655,P<0.05],差异均有统计学意义.DTT显示10例FCD患者皮质下白质纤维束较对侧明确减少,2例较对侧可能减少,主要表现为皮质下白质纤维稀疏,与深部白质纤维间联系减少.结论 FCD除了导致脑皮质结构异常外,也影响局部皮质下白质纤维的发育,DTI是常规MR检查的重要补充.     

冠状动脉搭桥术后磁共振桥血管成像的初步探讨

目的 以ＭＲ成像评价桥血管开通及功能,探讨适用于国人冠状动脉搭桥（ＣＡＢＧ）术后的影像学随访手段,方法 用１．５ＴＭＲ机检查２７例ＣＡＢＧ术后患者的７４支桥血管,行屏气快速场回波（ＦＦＥ）序列扫描观察桥血管的开通。其中１６例４２支桥血管行相位对比磁共振血流成像（ＰＳＭＲＡｆｌｏｗ）,得出血流速度和流量曲线,对桥血管的开通进行再评价。结果 本组桥血管ＦＦＥ成像开通率为８９．２％（６６／７４）。以ＰＳ     

Spectral CT imaging in preoperative diagnosis of pancreatic insulinoma:a preliminary study

目的:探讨CT能谱成像分析在胰岛素瘤诊断中的价值.方法:回顾性分析采用能谱CT能谱模式双期增强扫描并经手术病理证实的30例胰岛素瘤患者的病例资料.分别采用70 keV单能图像、碘基图像和最佳keV能量图像进行重建,比较不同图像模式下胰岛素瘤的检出率和病灶的对比噪声比(CNR).结果:本组胰岛素瘤动脉期和门静脉期70 keV单能图像、最佳keV能量图像和碘基图像上CNR分别为3.18±2.21、3.77±2.37、3.13±2.18和1.77±1.25、2.20±1.38、1.87±1.08.配对t检验结果显示,70 keV单能图像、最佳keV能量图像和碘基图的CNR,动脉期图像均明显优于门静脉期(t=3.139,P=0.005;t=3.196,P=0.004;t=3.05,P=0.003).动脉期最佳keV能量图像上病灶CNR大于70 keV单能量图像;动脉期和门静脉期70 keV能量、最佳keV能量图像、碘基图、能谱多参数图像对胰岛素瘤的检出率分别为73.3％(22/30)、86.7％(26/30)、86.7％(26/30)、96.7％(29/30)和53.3％(16/30)、73.3％(22/30)、73.3％(22/30)、76.7％(23/30).结论:在诊断胰岛素瘤方面,不同能谱扫描模式下动脉期图像均优于门静脉期,最佳keV能量图像和碘基图优于70 keV单能量图像.能谱CT多参数图像联合应用有利于提高对胰岛素瘤的诊断准确性.     

Role of high-resolution ultrasonography without and with real-time spatial compound imaging in evaluating the injured posterior cruciate ligament: preliminary study

Purpose

This study sought to compare high-resolution ultrasonography (HRUS) without and with compound imaging in evaluating the injured posterior cruciate ligament (PCL).

Materials and methods

Thirteen patients with a magnetic resonance imaging (MRI) diagnosis of PCL lesions (ten acute and three chronic) and 20 healthy controls underwent conventional and compound HRUS performed by the same radiologist who was blinded to the subjects’ case-control status. The PCL was scanned in a longitudinal direction in all cases. HRUS images were assessed for PCL thickness by two other radiologists blinded to the number and type of PCL injury. PCLs were classified as normal or injured, and the latter as having acute or chronic injuries. Intermethod reproducibility of measuring PCL thickness was assessed on conventional and compound HRUS images.

Results

Complete agreement in classifying normal or injured PCL and acute or chronic PCL injuries was achieved. PCL thickness in volunteers was 4.5±0.7 mm on conventional images and 4.6±0.7 mm on compound images. On conventional and compound HRUS images, the thickness of acutely injured PCL was 9.1±1.5 mm and 9.2±1.7 mm, respectively, and that of chronically injured PCL was 7±0.9 mm and 7±0.8 mm. Intermethod reproducibility of PCL thickness measurements on conventional vs. compound HRUS images was 98.6%.

Conclusions

HRUS is a reliable technique for studying the PCL and detecting PCL injuries.     

Diffusion kurtosis imaging features of renal cell carcinoma: a preliminary study

Objective:To explore the feasibility of diffusion kurtosis imaging (DKI) in differentiating different types of renal cell carcinoma (RCC).Methods:36 patients with clear cell RCC (CCRCC, low-grade,n = 20 and high-grade, n = 16), 19 with papillary RCC, 11 with chromophobe RCC, and 9 with collecting duct carcinoma (CDC) were examined with DKI technique. b values of 0, 500 and 1000 s/mm² were adopted. The DKI parameters, i.e., mean diffusivity (MD), mean kurtosis (MK), kurtosis anisotropy (KA), radial kurtosis (RK) and signa-to-noise ration (SNR) of DKI images at different b values were used.Results:The mean SNRs of DKI images at b = 0, 500 and 1000 s/mm² were 32.8, 14.2 and 9.18, respectively. For MD parameter, a significant higher value was shown in CCRCC than those of papillary RCC, chromophobe RCC and CDC (p < 0.05). In addition, both chromophobe RCC and CDC have larger MD values than papillary RCC (p < 0.05), however, there was no significant differences between chromophobe RCC and CDC (p > 0.05). For MK, KA and RK parameters, a significant higher value was shown in papillary RCC than those of CCRCC, chromophobe RCC and CDC (p < 0.05). Moreover, both chromophobe RCC and CDC have significantly larger values of MK, KA and RK than CCRCC (p < 0.05).Conclusion:Our preliminary study demonstrated significant differences in the DKI parameters between the subtypes of RCCs, given an adequate SNR of DKI images.Advances in knowledge:1.The MD value is the best parameter to distinguish CCRCC from other RCCs.2.The MK, KA and RK values are the best parameters to distinguish papillary RCC from other RCCs.3.DKI is able to provide images with sufficient SNRs in kidney disease.

Clear cell renal cell carcinoma (CCRCC) is the most common type of renal cell carcinoma (RCC), accounting for approximately 70% of all renal tumours. ¹ They are mostly sporadic but can also be hereditary to other RCCs such as chromophobe renal cell carcinoma (chromophobe RCC), papillary renal cell carcinoma (papillary RCC), collecting duct carcinoma (CDC) and so on. Interestingly, although CCRCC and other RCCs share similar ontogenic, histologic and some imaging features, RCCs exhibit differences in prognosis and treatment. ² The CCRCC and CDC have a poor prognosis with many being metastatic at presentation. About two-thirds of CDC patients die of their disease within 2 years of diagnosis. However, papillary RCC and chromophobe RCC are RCC subtypes with favorable prognosis compared with CCRCC and CDC because of their slower growth, significantly lower metastasis, progression, and death rate. ^3,4 For CCRCC and CDC, radical operations are acceptable, while for papillary or chromophobe RCC, minimally invasive techniques, such as neon-sparing surgery, ablation, and even active surveillance, are more feasible management considerations. ⁵ Pre-operative pathological stratification is an important means to evaluate the degree of malignancy and make the best treatment plan.The current imaging techniques, e.g. CT or anatomical MRI, have changed the management of renal masses by accurate detection and characterization of small masses. However, for some of atypical malignant or benign lesions, these methods still have shortcomings. Assessment of apparent diffusion coefficient (ADC) has also shown useful in distinguishing benign renal tumors from RCCs, especially for cystic renal tumours. ^6,7 These results are promising, however, there is significant overlap in ADC values between different RCC subtypes as well as between RCCs and benign lesions, and a more accurate characterization method is needed.Alternatively, diffusion kurtosis imaging (DKI), as an extension of the conventional diffusion imaging model, ⁸ estimates the kurtosis tensor, being able to quantitatively assess the deviation of the diffusion from the Gaussian form. ⁹ DKI can provide different diffusion parameters, i.e. MD (mean diffusivity), FA (fractional anisotropy), MK (mean kurtosis), KA (kurtosis anisotropy) and RK (radial kurtosis). DKI can provide a unique view of tissue perfusion without the use of exogenous contrast agents. Compared with the conventional imaging methods (CT or MRI), DKI can better reveal the complexity of organizational structure and accurate information about water diffusion because it considers the non-Gaussian behavior of water in biological tissues. ¹⁰ Huang et al ¹¹ used DKI in normal human kidney with b values of 0, 500 and 1000 s/mm². There results indicated DKI is feasible in normal human kidney, especially in the renal medulla, reflecting a more complex structure of renal medulla and suggesting that kurtosis maps obtained from DKI could provide additional information for revealing the renal microstructure and function. Rosenkrantz et al ¹² believed that the application of DKI sequence requires at least three b values and three directions. As reported previously, Ding et al. ¹³ has confirmed the feasibility of DKI between benign and malignant renal tumors. While promising results were obtained, such as the MD values of CCRCCs were higher than those of benign renal tumors, while MK values were lower than those of benign renal tumors. However, their study did not include other DKI parametric results, such as FA,KA or RK. Dai et al has also studied the diagnostic value of DKI for assessing renal tumour subtypes. ¹⁴ However, due to their limited number of tumor subtypes, further studies with larger sample size is needed to validate the results of their study.Therefore, the purpose of this study was to investigate the feasibility of DKI in the differentiation of different RCC types. To achieve this goal, we retrospectively studied the imaging characteristics of 75 cases of RCC with DKI, while ensuring theSNR of the image.     

Amide proton transfer MR imaging of prostate cancer: a preliminary study

Purpose:

To evaluate the capability of amide proton transfer (APT) MR imaging for detection of prostate cancer that typically shows a higher tumor cell proliferation rate and cellular density leading to an MRI‐detectable overall elevated mobile protein level in higher grade tumors.

Materials and Methods:

Twelve patients with biopsy‐proven prostate cancer were imaged on a 3 Tesla MR imaging system before prostatectomy. APT‐MR images were acquired by means of a single‐slice single‐shot turbo spin echo sequence with a saturation prepulse preparation using 33 different frequency offsets (?8 to 8 ppm, interval 0.5 ppm). For quantification we used the APT ratio (APTR) based on the asymmetry of the magnetization transfer ratio at 3.5 ppm in respect to the water signal. Tumor and peripheral zone benign regions of interest (ROIs) were delineated based on whole mount pathology slides after prostatectomy.

Results:

APTR in prostate cancer ROIs was 5.8% ± 3.2%, significantly higher than that in the peripheral zone benign regions (0.3% ± 3.2%, P = 0.002).

Conclusion:

APT‐MR imaging is feasible in prostate cancer detection and has the potential to discriminate between cancer and noncancer tissues. J. Magn. Reson. Imaging 2011;33:647–654. © 2011 Wiley‐Liss, Inc.