3.0 T磁共振3D CUBE T2 WI抑脂序列对肛瘘的诊断价值

目的 探讨3.0T常规MRI T2 WI抑脂序列联合三维超长回波链采集FSE(3D CUBE) T2 WI抑脂序列对肛瘘患者的临床诊断价值.方法 回顾性分析33例经手术证实的肛瘘患者术前常规MRI T2WI抑脂序列及3DCUBE T2 WI抑脂序列资料.比较两种技术评价肛瘘分型、瘘管支数、内口总数、外口数目、肛周脓肿和瘘管整体的优势,并与手术结果相对照.结果 手术发现33例肛瘘中,经括约肌瘘14例,括约肌间瘘10例,括约肌外瘘8例,括约肌上瘘1例.瘘管支数52个,内口45个,外口48个,肛周脓肿30个.常规MRI T2WI抑脂序列与常规MRI T2WI抑脂序列联合3D CBUE T2WI抑脂序列肛瘘的分型准确率分别为78.8％ (26/33)和87.9％ (29/33),差别无统计学意义(JP＞0.05);瘘管支数显示率分别为71.2％(37/52)和90.4％ (47/52),内口总数显示率分别为71.1％ (32/45)和91.1％ (41/45),差异具有统计学意义(P＜0.05).两种技术显示外口数目和肛周脓肿与手术结果一致.结论 常规MRI T2WI抑脂序列联合3D CUBE T2WI抑脂序列能准确显示瘘管支数、内口总数和瘘管整体,优于常规MRI T2 WI抑脂序列,为临床术前提供更详尽的影像解剖信息.     

T2-Weighted Liver MRI Using the MultiVane Technique at 3T: Comparison with Conventional T2-Weighted MRI

Objective

To assess the value of applying MultiVane to liver T2-weighted imaging (T2WI) compared with conventional T2WIs with emphasis on detection of focal liver lesions.

Materials and Methods

Seventy-eight patients (43 men and 35 women) with 86 hepatic lesions and 20 pancreatico-biliary diseases underwent MRI including T2WIs acquired using breath-hold (BH), respiratory-triggered (RT), and MultiVane technique at 3T. Two reviewers evaluated each T2WI with respect to artefacts, organ sharpness, and conspicuity of intrahepatic vessels, hilar duct, and main lesion using five-point scales, and made pairwise comparisons between T2WI sequences for these categories. Diagnostic accuracy (Az) and sensitivity for hepatic lesion detection were evaluated using alternative free-response receiver operating characteristic analysis.

Results

MultiVane T2WI was significantly better than BH-T2WI or RT-T2WI for organ sharpness and conspicuity of intrahepatic vessels and main lesion in both separate reviews and pairwise comparisons (p < 0.001). With regard to motion artefacts, MultiVane T2WI or BH-T2WI was better than RT-T2WI (p < 0.001). Conspicuity of hilar duct was better with BH-T2WI than with MultiVane T2WI (p = 0.030) or RT-T2WI (p < 0.001). For detection of 86 hepatic lesions, sensitivity (mean, 97.7%) of MultiVane T2WI was significantly higher than that of BH-T2WI (mean, 89.5%) (p = 0.008) or RT-T2WI (mean, 84.9%) (p = 0.001).

Conclusion

Applying the MultiVane technique to T2WI of the liver is a promising approach to improving image quality that results in increased detection of focal liver lesions compared with conventional T2WI.     

脂肪抑制T2WI和MRI增强在慢性乙型肝炎活动期中的诊断价值

目的 探讨慢性乙型肝炎活动期的MRI表现,提高诊断的准确性.方法 回顾性分析经临床证实的75例乙型肝炎活动期患者MRI资料.71例行平扫+增强,4例行平扫;重症组12例,非重症组63例.在脂肪抑制T2WI序列下测量肝脏信号强度与右侧竖脊肌信号强度之比值(SII).对照组选择无肝病病史及腹部疾病的正常成人66名,同样测量SII并进行统计学分析.结果 慢性乙型肝炎活动期在脂肪抑制T2WI信号增高,高于右侧竖脊肌信号,慢性乙型肝炎组与正常对照组间的SII值差异有统计学意义(P＜0.05);非重症乙型肝炎组和重症乙型肝炎组与正常对照组间的SII值差异均有统计学意义(P＜0.05);非重症乙型肝炎组与重症乙型肝炎组间SII值差异无统计学意义(P＞0.05).动脉期肝脏多发斑片状或网格样明显强化区,多分布于门静脉周围及肝包膜下,部分病例出现延迟廓清表现,少数重症病例肝脏散在小斑片状无强化区.61例存在Glisson囊炎性渗出,23例出现胆囊壁水肿增厚,23例存在胆汁淤积,13例出现腹腔积液,63例有肝门区多发小淋巴结.结论 乙型肝炎活动期患者的MR表现有一定的特征性,有助于提高诊断的准确性.     

Multicenter Validation of Mean Upper Cervical Cord Area Measurements from Head 3D T1-Weighted MR Imaging in Patients with Multiple Sclerosis

BACKGROUND AND PURPOSE:Spinal cord atrophy is a common and clinically relevant characteristic in multiple sclerosis. We aimed to perform a multicenter validation study of mean upper cervical cord area measurements in patients with multiple sclerosis and healthy controls from head MR images and to explore the effect of gadolinium administration on mean upper cervical cord area measurements.MATERIALS AND METHODS:We recruited 97 subjects from 3 centers, including 60 patients with multiple sclerosis of different disease types and 37 healthy controls. Both cervical cord and head 3D T1-weighted images were acquired. In 11 additional patients from 1 center, head images before and after gadolinium administration and cervical cord images after gadolinium administration were acquired. The mean upper cervical cord area was compared between cervical cord and head images by using intraclass correlation coefficients (ICC) for both consistency (ICC_consist) and absolute (ICC_abs) agreement.RESULTS:There was excellent agreement of mean upper cervical cord area measurements from head and cervical cord images in the entire group (ICC_abs = 0.987) and across centers and disease subtypes. The mean absolute difference between the mean upper cervical cord area measured from head and cervical cord images was 2 mm² (2.3%). Additionally, excellent agreement was found between the mean upper cervical cord area measured from head images with and without gadolinium administration (ICC_abs = 0.991) and between the cervical cord and head images with gadolinium administration (ICC_abs = 0.992).CONCLUSIONS:Excellent agreement between mean upper cervical cord area measurements on head and cervical cord images was observed in this multicenter study, implying that upper cervical cord atrophy can be reliably measured from head images. Postgadolinium head or cervical cord images may also be suitable for measuring mean upper cervical cord area.

Spinal cord atrophy is recognized as a common and clinically relevant characteristic in patients with multiple sclerosis.¹ Differences in cervical cord volume and area among patients with different phenotypes of MS and healthy controls (HCs) measured by MR imaging have been identified in many studies.^2–4 Furthermore, a modest or strong correlation between spinal cord atrophy and disability has been demonstrated in numerous studies, suggesting that spinal cord atrophy is an essential determinant of clinical disability and a potential outcome measure to monitor MS disease progression.^5–7 The measurement of the upper cervical cord area is a well-established method for the assessment of spinal cord atrophy and has been applied in most studies so far.^2,3,5,8,9 Both image acquisition and spinal cord segmentation are technically feasible and more accurate in the upper cervical region compared with other parts of the cord or the entire cord.¹⁰ In addition, the upper cervical cord is more frequently affected by MS pathology than lower parts of the spinal cord.¹¹Mean upper cervical cord area (MUCCA) can be measured by using 3D T1-weighted MR images of the cervical cord.^3,4 The MUCCA also has been measured recently on 3D T1-weighted MR images of the head covering the upper cervical cord, which has yielded promising results showing associations between MUCCA and clinical disability and disease progression.^2,5 Measuring the MUCCA from head MR images offers the opportunity to analyze MUCCA retrospectively in datasets without dedicated cervical 3D T1-weighted images, and it can reduce costs and patient burden in prospective studies by eliminating the need for separate cervical cord image acquisitions if these are only acquired to measure the MUCCA. An MR imaging contrast agent is commonly used to detect the blood-brain barrier breakdown and inflammation in new lesions^12,13 in patients with MS, which might influence the MUCCA measurements by tissue-contrast changes. The effect of the MR imaging contrast agent on MUCCA measurement also has to be investigated to ease the implementation of MUCCA as an auxiliary measurement in clinical practice. Although MUCCA measurements based on head 3D T1-weighted images have been successfully used in a monocenter study,¹⁴ multicenter validation is lacking. In addition, the possible effect of intravenous contrast administration on MUCCA measurements has not been investigated.Therefore, the aim of the current study was to validate the measurement of the MUCCA on the basis of head compared with cervical cord 3D T1-weighted images in patients with MS and healthy controls on different MR imaging systems by using different acquisition parameters from multiple centers and to explore the effect of gadolinium (Gd) administration on MUCCA measurements.     

Effectiveness of 3D T2-Weighted FLAIR FSE Sequences with Fat Suppression for Detection of Brain MR Imaging Signal Changes in Children

BACKGROUND AND PURPOSE:T2-weighted FLAIR can be combined with 3D-FSE sequences with isotropic voxels, yielding higher signal-to-noise ratio than 2D-FLAIR. Our aim was to explore whether a T2-weighted FLAIR–volume isotropic turbo spin-echo acquisition sequence (FLAIR-VISTA) with fat suppression shows areas of abnormal brain T2 hyperintensities with better conspicuity in children than a single 2D-FLAIR sequence.MATERIALS AND METHODS:One week after a joint training session with 20 3T MR imaging examinations (8 under sedation), 3 radiologists independently evaluated the presence and conspicuity of abnormal areas of T2 hyperintensities of the brain in FLAIR-VISTA with fat suppression (sagittal source and axial and coronal reformatted images) and in axial 2D-FLAIR without fat suppression in a test set of 100 3T MR imaging examinations (34 under sedation) of patients 2–18 years of age performed for several clinical indications. Their agreement was measured with weighted κ statistics.RESULTS:Agreement was “substantial” (mean, 0.61 for 3 observers; range, 0.49–0.69 for observer pairs) for the presence of abnormal T2 hyperintensities and “fair” (mean, 0.29; range, 0.23–0.38) for the comparative evaluation of lesion conspicuity. In 21 of 23 examinations in which the 3 radiologists agreed on the presence of abnormal T2 hyperintensities, FLAIR-VISTA with fat suppression images were judged to show hyperintensities with better conspicuity than 2D-FLAIR. In 2 cases, conspicuity was equal, and in no case was conspicuity better in 2D-FLAIR.CONCLUSIONS:FLAIR-VISTA with fat suppression can replace the 2D-FLAIR sequence in brain MR imaging protocols for children.

3D (volume) gradient-echo T1-weighted sequences are a well-established part of brain MR imaging protocols due to the intrinsically higher SNR compared with 2D sequences and the ability to obtain optimal MPR.¹ However, abnormalities of the brain are usually detected as nonspecific areas of variably increased signal in T2WI. FLAIR images are preferable to FSE images for detecting such T2 abnormalities because suppression of the CSF high signal results in an improved gray-scale dynamic range.²T2-weighted FLAIR can be combined with 3D-FSE sequences with isotropic voxels that are variably named by different vendors, including volume isotropic turbo spin-echo acquisition (VISTA; Philips Healthcare, Best, the Netherlands), SPACE (sampling perfection with application-optimized contrasts by using different flip angle evolution; Siemens, Erlangen, Germany), Cube (GE Healthcare, Milwaukee, Wisconsin), isoFSE (http://www.hitachimed.com/products/mri/oasis/Neurological/isoFSE), and 3D mVox (Toshiba, Tokyo, Japan). Such T2-weighted FLAIR 3D-FSE sequences have a higher SNR than 2D-FLAIR, enable MPR, and are less affected by CSF flow artifacts,^3–6 which are more prominent in sedated children at a higher field strength 3T magnet.^7–9Theoretically, suppression of fat signal with spectral presaturation could improve the sensitivity of FLAIR-VISTA by further narrowing the gray-scale dynamic range.²The purpose of the present study was to evaluate whether a FLAIR-VISTA sequence with fat suppression shows abnormal brain T2 signal hyperintensities with better conspicuity than a 2D-FLAIR sequence on a single axial plane in children.     

3台不同厂家3.0T MR设备测量非酒精性脂肪性肝病患者肝脏质子密度脂肪分数的一致性

目的评估在3台不同厂家3.0T MR设备上测量非酒精性脂肪性肝病(NAFLD)患者的肝脏质子密度脂肪分数(PDFF)的一致性.资料与方法前瞻性收集2018年9月—2019年7月于首都医科大学附属北京友谊医院经病理诊断为NAFLD患者30例,均于同一天先后在3台不同厂家3.0T MR设备(Philips Ingenia,...     

Carotid Plaque Characterization Using 3D T1-Weighted MR Imaging with Histopathologic Validation: A Comparison with 2D Technique

BACKGROUND AND PURPOSE:3D FSE T1WI has recently been used for carotid plaque imaging, given the potential advantages in contrast and spatial resolutions. However, its diagnostic performance remains unclear. Hence, we compared the ability of this technique to readily assess plaque characteristics with that of conventional images and validated the results with histologic classification.MATERIALS AND METHODS:We prospectively examined 34 patients with carotid stenosis who underwent carotid endarterectomy by using 1.5T scanners and obtained 3D-FSE T1WI and 2D spin-echo T1WI scans. After generating reformatted images obtained from the 3D-FSE T1-weighted images, we calculated the contrast ratios for the plaques and the adjacent muscles and compared these findings with the pathologic classifications.RESULTS:Carotid plaques were histologically classified as types VII, VIII, IV–V, or VI. With 3D-FSE T1WI, the range of contrast ratios for each classification was the following: 0.94–0.97 (median, 0.95), 0.95–1.29 (median, 1.10), 1.33–1.54 (median, 1.42), and 1.53–2.12 (median, 1.80), respectively. With 2D imaging, the range of contrast ratios for each classification was the following: 0.79–1.02 (median, 0.90), 0.88–1.19 (median, 1.01), 1.17–1.46 (median, 1.23), and 1.55–2.51 (median, 2.07), respectively. Results were significantly different among the 4 groups (P < .001). Sensitivity and specificity for discriminating vulnerable plaques (IV–VI) from stable plaques (VII, VIII) were both 100% for the 3D technique and 100% and 91%, respectively, for the 2D technique.CONCLUSIONS:3D-FSE T1WI accurately characterizes intraplaque components of the carotid artery, with excellent sensitivity and specificity compared with those of 2D-T1WI.

Cervical carotid stenosis is an important cause of cerebral infarction and transient ischemic attack. Carotid endarterectomy or carotid artery stent placement is performed to prevent future stroke events but may also cause embolic complications during the surgery, especially if the plaque contains substantial vulnerable components such as intraplaque hemorrhage or lipid.^1,2 Therefore, establishing a method for characterizing intraplaque components is an important prerequisite for predicting perisurgical complications.Several modalities have been used for plaque characterization, including ultrasonography and MR imaging. Although ultrasonography is widely used, the interpretation is typically subjective and may be impossible in the presence of extensive calcification or a high-positioned carotid bifurcation. Although gray-scale median and integrated backscatter have been introduced as quantitative metrics, previous reports suggest that they are unsuitable for evaluating intraplaque components.^3,4 MR plaque imaging is another popular method for assessing plaque characteristics. Although various imaging techniques have been used, a 2D spin-echo (SE) T1WI technique with appropriate scanning parameters has been reported to accurately quantify intraplaque components, compared with other conventional techniques.^5–8 Recently, a 3D T1WI FSE technique has been adopted for this purpose because it can minimize partial volume effects and motion artifacts, as well as enhance black-blood effects, while maintaining T1WI contrast. However, whether the 3D-FSE technique can more accurately discriminate among intraplaque components than the more conventional techniques, such as 2D-SE T1WI, remains unknown. Hence, in the present study, we investigated whether the diagnostic accuracy of 3D-FSE T1WI, in terms of carotid plaque characterization, is comparable with that of 2D-SE T1WI, by using pathologic specimens excised from carotid endarterectomy as our validation standards.     

臂丛神经磁共振IDEALT2WI和CUBEFlexT2WI成像

目的比较磁共振脂肪抑制FSET2WI、STIRT2WI、IDEALT2WI及CUBEFlexT2WI4种方法显示正常臂丛神经的优劣。资料与方法对14例自愿者行臂丛神经MRI脂肪抑制FSET2WI、STIRT2WI、IDEALT2WI及CUBEFlexT2WI检查。对图像脂肪抑制质量进行肉眼分级评估,并测量信噪比和对比噪声比。结果 IDEALT2WI、CUBEFlexT2WI脂肪抑制质量明显优于FSET2WI(P<0.05),与STIRT2WI相比差异无统计学意义(P>0.05)。信噪比、对比噪声比均值比较各组间差异均有统计学意义(P<0.05),IDEALT2WI>CUBEFlexT2WI>FSET2WI>STIRT2WI。IDEALT2WI和CUBEFlexT2WI图像均可选择不同厚度重建、斜面重建等,从而可显示臂丛神经各段。结论 IDEALT2WI、CUBEFlexT2WI能提供均匀稳定的脂肪抑制,图像信噪比高,可清晰显示臂丛神经。     

MR Imaging of the Spine at 3.0T with T2-Weighted IDEAL Fast Recovery Fast Spin-Echo Technique

Objective

To compare the iterative decomposition of water and fat with echo asymmetry and the least-squares estimation (IDEAL) method with a fat-saturated T2-weighted (T2W) fast recovery fast spin-echo (FRFSE) imaging of the spine.

Materials and Methods

Images acquired at 3.0 Tesla (T) in 35 patients with different spine lesions using fat-saturated T2W FRFSE imaging were compared with T2W IDEAL FRFSE images. Signal-to-noise ratio (SNR)-efficiencies measurements were made in the vertebral bodies and spinal cord in the mid-sagittal plane or nearest to the mid-sagittal plane. Images were scored with the consensus of two experienced radiologists on a four-point grading scale for fat suppression and overall image quality. Statistical analysis of SNR-efficiency, fat suppression and image quality scores was performed with a paired Student''s t test and Wilcoxon''s signed rank test.

Results

Signal-to-noise ratio-efficiency for both vertebral body and spinal cord was higher with T2W IDEAL FRFSE imaging (p < 0.05) than with T2W FRFSE imaging. T2W IDEAL FRFSE demonstrated superior fat suppression (p < 0.01) and image quality (p < 0.01) compared to fat-saturated T2W FRFSE.

Conclusion

As compared with fat-saturated T2W FRFSE, IDEAL can provide a higher image quality, higher SNR-efficiency, and consistent, robust and uniform fat suppression. T2W IDEAL FRFSE is a promising technique for MR imaging of the spine at 3.0T.     

Uterine Artery Embolization for Symptomatic Fibroids with High Signal Intensity on T2-Weighted MR Imaging

Objective

To evaluate the effectiveness of uterine artery embolization (UAE) for treating symptomatic fibroids with high signal intensity (SI) on magnetic resonance (MR) T2-weighted imaging (T2WI).

Materials and Methods

A total of 537 cases, consisting of 14 patients with high SI fibroids on T2WI (T2 high group), were retrospectively included and compared with 28 randomly selected patients with low SI fibroids on T2WI (control group). High SI of a predominant fibroid on T2WI was defined as having the same or higher SI than the myometrium. Patient ages ranged from 28 to 52 years (mean, 38.1 years). All patients underwent MRI before and after UAE. Predominant fibroid and uterine volumes were calculated with MR images. Symptom status in terms of menorrhagia and dysmenorrhea was scored on a scale of 0-10, with 0 being no symptoms and 10 being the baseline, or initial symptoms.

Results

Of the patients in the T2 high group, 13 out of 14 (92.9%) patients demonstrated complete necrosis of the predominant fibroids. The mean volume reduction rates of the predominant fibroids in the T2 high group was 61.7% at three months after UAE, which was significantly higher than the volume reduction rates of 42.1% noted in the control group (p < 0.05). Changes in symptom scores for menorrhagia and dysmenorrhea after UAE (baseline score minus follow-up score) were 4.9 and 7.5 in T2 high group and they were 5.0 and 7.7 in control group, suggesting a significant resolution of symptoms (p < 0.01) in both groups but no significant difference between the two groups.

Conclusion

UAE is effective for uttering fibroids showing high SI on T2WI. The mean volume reduction rate of the predominant fibroids three months after UAE was greater in the T2 high group than in the control group.     

磁共振扩散加权与T2加权成像对肝脏局灶性病变检出的比较研究

目的比较磁共振扩散加权成像(diffusion-weighted imaging,DWI)与T2加权成像(T2-weighted imaging,T2WI)对肝脏局灶性病变的检出效能。方法选择T2WI与DWI2种序列均进行了检查的57例患者共79个病灶(45个恶性,34个良性)纳入本次研究。2位读片者采用盲法分别阅读T2WI与DWI图像。第3位读片者测量病灶和邻近肝实质在DWI及T2WI上的信号强度,计算病灶/肝信号强度比(contrast ratios,CR)。比较2种序列之间检出率及CR值的差异。结果2种序列对恶性病灶的检出率之间的差异无统计学意义,T2WI对全部病灶和良性病灶的检出率高于DWI(2位读片者P<0.001)。对于恶性病灶,当在一种序列上检出病灶即计为检出时,则T2WI+DWI的检出率高于DWI(读片者1P=0.008,读片者2P<0.001),但与T2WI之间检出率的差异无显著性。共对46个病灶测量了CR。良性病灶的CR值在T2WI高于DWI(P=0.008),恶性病灶和全部病灶的CR值在2种序列之间的差异无统计学意义。结论DWI对恶性病灶的检出效能低于T2WI,对良性病灶的检出效能也不及...     

Predicting Carotid Plaque Characteristics Using Quantitative Color-Coded T1-Weighted MR Plaque Imaging: Correlation with Carotid Endarterectomy Specimens

BACKGROUND AND PURPOSE:MR plaque imaging is used to evaluate the risk of embolic complications during carotid endarterectomy and carotid artery stent placement. However, its performance for characterizing intraplaque components has varied across studies and is generally suboptimal. Hence, we correlated MR imaging results with histologic findings to determine whether a combination of high-contrast T1-weighted imaging and quantitative image analysis could readily determine plaque characteristics.MATERIALS AND METHODS:We prospectively examined 40 consecutive patients before carotid endarterectomy by using a 1.5T scanner and axial T1-weighted spin-echo images under optimized scanning conditions. The percentage areas of intraplaque fibrous tissue, lipid/necrosis, and hemorrhage were calculated automatically by using the software with previously reported cutoff values and were compared with those of the specimens. The thickness of the fibrous cap was also measured manually.RESULTS:The percentage areas of fibrous, lipid/necrotic, and hemorrhagic components were 5.7%–98.7%, 1.3%–65.7%, and 0%–82.0%, respectively, as determined by the MR images, whereas the corresponding values were 4.8%–92.3%, 7.0%–93.8%, and 0%–70.4%, respectively, as determined by histologic examination. Significant positive correlation and agreement were observed between MR images and histologic specimens (r = 0.92, 0.79, and 0.92; intraclass correlation coefficients = 0.91, 0.67, and 0.89; respectively). Thickness of the fibrous caps on MR images (0.21–0.87 mm) and in the specimens (0.14–0.83 mm) also showed positive correlation and agreement (r = 0.61, intraclass correlation coefficient = 0.59).CONCLUSIONS:Quantitative analysis of high-contrast T1-weighted images can accurately evaluate the composition of carotid plaques in carotid endarterectomy candidates.

Estimation of the composition of carotid plaques is important to help identify the risk of embolic events during carotid endarterectomy or carotid artery stent placement. Ultrasonography has commonly been used for this purpose, but it is not useful in cases of extensive calcification or if the plaque is in a higher location; furthermore, ultrasonography lacks reliable and versatile quantitative metrics.^1–4 Thus, as a complement to ultrasonography, MR plaque imaging is now widely used to estimate plaque composition. However, plaque characterization remains unsatisfactory, presumably owing to the deterioration of image contrast, secondary to inappropriate scanning techniques and/or protocols.⁵ Recently, a nongated T1-weighted spin-echo (SE) technique with appropriately fixed scanning parameters was reported to improve and stabilize intraplaque contrast, compared with a cardiac-gated black-blood fast spin-echo technique in which T1-weighting tended to be attenuated and fluctuated according to a heart-rate-dependent setting of the TR.⁶ The nongated T1-weighted spin-echo method has been found to allow accurate estimation of the main plaque components with minimal overlap,⁷ suggesting potential advantages over other imaging modalities in terms of plaque characterization. However, quantitative evaluation of intraplaque composition has not been achieved by this method. Hence, in the present study, we used a quantitative color-coded image-analysis software to characterize intraplaque distribution by percentage area of fibrous, lipid/necrotic, and hemorrhagic tissues and to determine the accuracy of this method for predicting plaque characteristics by correlating the results with histologic findings from the carotid endarterectomy specimens.     

Value of Dynamic Contrast-Enhanced T1-weighted MR Imaging Combined With T2*-Weighted First-Pass Perfusion Imaging in Differential Diagnosis of Breast Tumors

目的 评价在单次乳腺MRI中,结合T1WI动态增强成像(dynamic contrast-enhanced T1-weighted imaging,DCE-T1WI)与T2*W首过灌注成像(T2*-weighted first-pass perfusion imaging,PWI-T2* WI)对乳腺良、恶性病变鉴别诊断的诊断价值.资料与方法 40例患者在一次乳腺MRI中,先进行DCE-T1WI,随后进行PWI-T2* WI.结果 DCE-T1WI如果将流出型时间-信号强度曲线作为诊断病灶恶性的阈值,诊断敏感性为74.2％,特异性为88.9％.良、恶性病灶早期强化率差异有统计学意义(P ＜0.001).如果将病灶早期强化率90％作为诊断恶性病灶的阈值,敏感性与特异性分别为83.9％、77.8％;PWI-T2* WI将病灶早期信号丢失率20％作为诊断恶性的阈值,敏感性、特异性分别为90.3％、92.9％.良、恶性病灶在PWI-T2* WI早期信号丢失率的重叠范围小于DCE-T1WI早期强化率的重叠范围.就乳腺良、恶性病灶的鉴别诊断价值而言,PWI-T2* WI中病灶早期信号丢失率高于DCE-T1WI病灶早期强化率(A值分别为0.910 vs 0.791,P＝0.000).结论 PWI-T2* WI在鉴别乳腺病灶的良、恶性方面有很高的特异性,在单次乳腺MRI中联合DCE-T1WI与PWI-T2*WI,能够提高乳腺癌诊断的准确性.     

Diffusion MR Imaging with T2-based Water Suppression (T2wsup-dMRI)

Purpose: This study proposes and assesses a new diffusion MRI (dMRI) technique to solve problems related to the quantification of parameter maps (apparent diffusion coefficient [ADC] or mean diffusivity [MD], fractional anisotropy [FA]) and misdrawing of fiber tractography (FT) due to cerebrospinal fluid (CSF)-partial volume effects (PVEs) for brain tissues by combining with the T2-based water suppression (T2wsup) technique.Methods: T2wsup–diffusion-weighted imaging (DWI) images were obtained by subtracting those images from the acquired multi-b value (b) DWI images after correcting the signal intensities of multiecho time (TE) images using long TE water signal-dominant images. Quantitative parameter maps and FT were obtained from minimum data points and were compared with those using the standard (without wsup) DWI method, and partly compared with those obtained using other alternative DWI methods of applying fluid attenuation inversion recovery (FLAIR), non-b-zero (NBZ) by theoretical or noise-added simulation and MR images.Results: In the T2wsup-dMRI method, the hyperintense artifacts due to CSF-PVEs in MRI data were dramatically suppressed even at lower b (≲ 500 s/mm²) while keeping the tissue SNR. The quantitative parameter map values became precisely close to the pure tissue values precisely even in water (CSF) PVE voxels in healthy brain tissues (T2 ≲ 100 ms). Furthermore, the fiber tracts were correctly connected, particularly at the fornix in closest contact to the CSF.Conclusion: Solving the problem of CSF-PVE in the current dMRI technique using our proposed T2wsup-dMRI technique is easy, with higher SNR than those obtained with FLAIR or NBZ methods when applying to healthy brain tissues. The proposed T2wsup–dMRI could be useful in clinical settings, although further optimization of the pulse sequence and processing techniques and clinical assessments are required, particularly for long T2 lesions.     

Improved Lesion Detection by Using Axial T2-Weighted MRI with Full Spinal Cord Coverage in Multiple Sclerosis

BACKGROUND AND PURPOSE:Identification of lesions in specific locations gains importance in multiple sclerosis imaging diagnostic criteria. In clinical routine, axial scans are usually exclusively obtained to depict the cervical spinal cord or used to confirm suspected lesions on sagittal scans. We sought to evaluate the detection rate for MS lesions on axial T2WI scans with full spinal cord coverage in comparison with sagittal scans.MATERIALS AND METHODS:One hundred fifteen patients with definite or suspected MS underwent an MR imaging examination including 3-mm sagittal and 3.5-mm axial T2-weighted images with full spinal cord coverage. T2WI lesions were identified on axial and sagittal scans independently by 2 raters. Axial diameter, craniocaudal extension, lesion intensity, and location were analyzed.RESULTS:Four hundred forty-nine of 509 (88.2%) lesions were detected on axial and 337/509 (66.2%) on sagittal scans. Only 277/449 (61.7%) axial lesions were also detected on sagittal images. The number of lesions visible on sagittal and axial images was dependent on the axial lesion diameter (P < .001).CONCLUSIONS:Axial T2WI scans with full spinal cord coverage showed 22% more lesions in patients with MS in comparison with sagittal scans, especially for lesions with small axial diameters. We suggest including biplanar spinal MR imaging with full spinal cord coverage for lesion detection in MS in clinical routine and for clinical studies.

Multiple sclerosis is a chronic inflammatory disease, considered the most common demyelinating process involving the central nervous system.¹ The diagnosis requires typical clinical findings in addition to the evidence of lesions in the CNS disseminated in time and space seen on MR imaging of the brain or spinal cord.² While the diagnostic focus of most multiple sclerosis studies is still based on MR imaging of the brain, several studies have revealed spinal cord lesions in 75%–90% of patients with clinically diagnosed MS.^3–6 As many as 20% of spinal MS lesions are isolated, without coexisting brain lesions.¹Spinal cord abnormalities seen on MR imaging were incorporated into the McDonald Diagnostic Criteria for MS in 2005.^7,8 Since the revision of the McDonald Diagnostic Criteria for MS in 2010,⁹ they have gained even more importance because better spinal cord lesion detection potentially impacts the recognition of the dissemination of MS lesions in space.In 2006, a consortium of MS centers published consensus guidelines with a standardized MR imaging protocol for spinal cord imaging in MS, recommending a 3-plane scout; a pre- and post-contrast-enhanced sagittal T1; a pre-contrast-enhanced sagittal FSE proton-density/T2; and additionally, only in case of suspected lesions, a pre-contrast-enhanced axial FSE proton-density/T2 and a post-contrast-enhanced axial T1.¹⁰ In the clinical routine of MS diagnostics, axial scans are typically obtained exclusively with coverage of the cervical spinal cord or are used to confirm suspected lesions in sagittal scans. This is mainly due to the long scanning time of axial scans with full spinal cord coverage.So far in most MS studies, spinal cord lesions were evaluated and marked on the sagittal plane,^11,12 while some groups included axial scans covering only the cervical spine^13–15 and very few studies analyzed the axial and sagittal planes of the entire spinal cord.^3,16 Also, lesion location and size were described on sagittal scans only or on axial scans covering the cervical spinal cord exclusively.¹⁵We hypothesized that axial T2WI scans with full spinal cord coverage would detect more T2WI lesions in comparison with sagittal scans. We sought to evaluate detection rates for T2WI lesions on axial and sagittal scans in relation to the distribution and extent of spinal cord lesions in patients with MS. To our knowledge, this is the first study focusing on the clinical application of axial 3.5-mm scans with full spinal cord coverage. We used a sequence with reasonable duration, feasible in clinical routine.     

3.0T磁共振DWI结合T2加权成像诊断前列腺癌侵犯膀胱

目的 探讨T2WI及DWI 2种成像序列对前列腺癌(PCa)侵犯膀胱的诊断价值.方法 68例经病理证实的PCa患者在行3.0T MR前列腺常规和DWI(b值分别为0、800 s/mm2)扫描后被诊断为PCa侵犯膀胱,所有患者均行膀胱镜检查.分析所有PCa癌灶、受侵膀胱和未受侵膀胱壁的MRI表现,比较其ADC值.采用5分制评分,将所得结果与膀胱镜病理结果对照,用SPSS11.5分别做受试者工作特征曲线(ROC)分析比较各组方法诊断的敏感度和特异度.结果 膀胱镜检查45例(66%)患者病理证实为PCa侵犯膀胱,PCa癌灶、受侵膀胱壁和正常膀胱壁的ADC值分别为(0.931±0.098)×10-3mm2/s,(0.963±0.155)×10-3mm2/s和(1.517±0.103)×10-3mm2/s,受侵膀胱壁的ADC值明显低于正常膀胱壁(P＜0.05),而PCa癌灶和受侵膀胱壁的ADC值之间无明显差异.分别应用T2WI和DWI诊断PCa侵犯膀胱的ROC曲线下面积(AUC)明显低于联合2种成像方法(P＜0.05).结论 PCa侵犯膀胱的ADC值明显低于正常膀胱壁;联合应用DWI和T2WI诊断PCa侵犯膀胱优于单独使用DWI或T2WI.