子宫内膜间质肉瘤的MRI表现

目的:探讨子宫内膜间质肉瘤的MRI表现特点。方法:回顾性分析7例经手术及病理证实的子宫内膜间质肉瘤患者的临床和MRI资料。所有病例均行MRI平扫。结果:本组7例患者子宫体积均增大。6例病变位于宫腔内,呈息肉状突向宫腔或弥漫性填充宫腔;1例位于子宫肌壁间,类似囊性变性子宫肌瘤。2例囊实混合性占位,5例实性占位。7例ESS病变直径范围为2.5cm-15cm,平均8.8cm。肿瘤在MRI平扫上5例T1WI 呈等信号或低信号,T2WI呈稍高信号;2例T1WI呈等及低信号,T2WI呈稍高为主的混杂信号,伴有出血或坏死囊变,其中1例位于子宫肌壁间。6例可见向子宫肌层侵润性生长,子宫T2WI结合带低信号中断或消失,其中1例可见宫颈、双侧输卵管壁、卵巢及膀胱受侵,1例子宫肌层及宫旁可见扭曲条点状流空信号影。4例合并少量盆腔积液,2例合并子宫肌瘤,1例合并卵巢滤泡囊肿,3例合并增殖期子宫内膜。病理示低度恶性ESS 6例,未分化ESS 1例。结论:子宫内膜间质肉瘤好发于宫腔内,也可见于子宫肌壁间,多向子宫肌层浸润性生长,于T1WI呈等或低信号,T2WI呈稍高信号,伴出血或坏死囊变时呈T2WI稍高信号为主的混杂信号,其在MRI上具有一定的信号特点,能为该病的诊断提供帮助。     

MRI of Lumbar and Sacral Plexus Nerve Sheath Tumours

Seven patients with peripheral nerve sheath tumours affecting the lumbo-sacral plexus were examined with MR imaging utilizing a 1.5T magnet and spin echo pulse sequences. The majority of tumours were homogeneous in signal intensity and isointense with adjacent muscle on T₁ weighted images and showed markedly increased signal intensity on T₂ weighted images with central areas of relatively low signal intensity. An attempt to obtain a pathological correlation with the areas of low signal on T₂ weighted images was unsuccessful. The use of Gadolinium DTPA in one patient resulted in irregular enhancement of both a neurogenic sarcoma and smaller neurofibromas. The multiplanar imaging capabilities, high soft tissue contrast, non-invasiveness, lack of ionizing radiation and the characteristic appearance of neural tumours makes MR ideal for imaging these lesions.     

椎管内囊性神经鞘瘤影像学特点

目的:研究MRI对椎管内囊性神经鞘瘤的诊断价值及鉴别诊断。方法:回顾性分析经病理证实的MR表现为椎管内囊性神经鞘瘤10例,6名男性,4名女性,年龄范围37~62岁,平均年龄51.4岁。结果:MRI显示病变均位于髓外硬膜下,T1WI表现为低信号,T2WI表现为高信号,增强扫描显示为环状强化。结论:MRI是诊断椎管内囊性神经鞘瘤的重要手段,其MR及增强扫描表现比较典型,对外科手术计划有很大帮助。由于其典型的强化特点鉴别诊断并不复杂。     

MR化学位移伪影与股骨头缺血坏死"双线征"

目的探讨股骨头缺血坏死MRIT2WI上“双线征”与化学位移伪影之间的关系。方法前瞻性研究130例临床及影像学诊断股骨头缺血坏死患者,从中挑选出48例(60髋)MRIT2WI上出现“双线征”的病例,进行不同扫描序列检查。并对其中1髋进行MRI与病理对照研究。结果1.5TMRI机对化学位移伪影敏感性高于0.5TMRI机。20个股骨头T1WI改变频率编码后,单线变为3线;34个T2WI改变频率编码后,双线变为3～4线;所有病例T2WI STIR图像双线仍然存在。大体以及组织切片上可见死骨、纤维肉芽组织和周围反应性成骨。结论化学位移伪影存在于T1WI及T2WI,且场强越高,越明显。股骨头坏死“双线征”与化学位移伪影无关。     

Comparative Study of Images with Pathology： Superparamagnetic Iron Oxide-enhanced Magnetic Resonance Image （MRI） of Splenic VX2 Tumor in Rats

Objective： To establish a rodent model of VX2 tumor of the spleen, to analyze relationship between the change of the signal intensity on superparamagnetic iron oxide enhanced magnetic resonance image （MRI） and pathologic change to evaluate the ability of superparamagnetic iron oxide enhanced MRI for detection of splenic metastases. Methods： 8 rodent models of VX2 tumor of spleen were established successfully. The images were obtained before and after administration of superparamagnetic iron oxide. T1-weighted spin-echo （SE） pulse sequence with a repetition time （TR） of 450 msec, and echo time （TE） of 12 msec （TR/TE=450/12） was used. The imaging parameters of T2-weighted SE pulse sequence were as follows： TR/TE=4000/128. Results： On plain MR scanning T1-weighted splenic VX2 tumor showed hypointensity or isointensity which approximated to the SI of splenic parenchyma. Therefore all lesions were not displayed clearly. On superparamagnetic iron oxide enhancement T2WI sequence the SI of splenic parenchyma decreased obviously with percentage of signal intensity loss （PSIL） of 55.04%, But the SI of tumor was not evidently changed with PSIL of 0.87%. Nevertheless the SNR of normal splenic parenchyma around the lesions had obvious difference （P〈0.001） comparatively. Therefore the contrast between tumor and spleen increased, and tumor displayed more clearly. Moreover the contrast-to-noise （CNR） between VX2 tumor and splenic parenchyma had an evident difference before and after admininstration of superparamagnetic iron oxide （P〈0.001）. Conclusion： On superparamagnetic iron oxide enhancement T1WI sequence the contrast of tumor-to-spleen is poor. Therefore it is not sensitive to characterize the lesions in spleen. On superparamagnetic iron oxide enhanced T2WI the contrast degree of lesions increases obviously. Consequently, superparamagnetic iron oxide -enhanced T2WI MRI scanning can improve the rate of detection and characterization for lesions of spleen.     

A Prospective Evaluation of T2-Weighted First-Pass Perfusion MR Imaging In Diagnosing Breast Neoplasms

Objective To compare the results from breast cancer patients who undergo T2-weighted first-pass perfusion imaging after dynamic contrast-enhanced T1-weighted imaging during the same examination, and to evaluate if T2-weighted imaging can provide additional diagnostic information over that obtained with T1-weighted imaging. Methods Twenty-nine patients with breast lesions verified by pathology (benign 12, malignant 17.) underwent MR imaging with dynamic contrast-enhanced T1-weighted imaging of the entire breasts, immediately followed by 6-sections of T2-weighted first-pass perfusion imaging of the lesions. The diagnostic indices were acquired by individual 3D T1-weighted enhancement rate criterion and the T2 signalintensity loss rate criterion. The sensitivity and specificity were calculated and the 2 methods were compared. Results With the dynamic.contrast-enhanced T1-weighted imaging, there was a significant differences between the benign and malignant breast lesions (t =2.563,P=0.016). However we found a considerable overlap between the signal intensity increase in the carcinomas and that in the benign lesions, for a sensitivity of 94% and a specificity of 25%. With T2-weighted first-pass perfusion imaging, there was a very significant difference between the benign and malignant breast lesions(t =4.777,P< 0.001), and the overlap between the signal intensity decrease in the carcinomas and that of the benign lesions on the T2-weighted images was less pronounced than the overlap in the T1-weighted images, for a sensitivity of 88% and a specificity of 75%. Conclusion T2-weighted first-pass perfusion imaging may help differentiate between benign and malignant breast lesions with a higher level of specificity. The combination of T1-weighted and T2-weighted imaging is feasible in a single patient examination and may improve breast MR imaging.     

Non-invasive MR thermography using the water proton chemical shift

Among various proton magnetic resonance (MR) parameters, such as longitudinal relaxation time, transverse relaxation time, diffusion coefficient and chemical shift, the chemical shift of water protons is recognized as the most reliable indicator of temperature. The chemical shift is the only frequency-based parameter and is independent of the other parameters, which are measured based on the intensity of the MR signal. In this paper, the basic principle and the recent progress in imaging temperature by spectroscopic techniques using the water proton chemical shift are discussed. The advantages of spectroscopic imaging over phase mapping for measuring temperature are that the former can distinguish water resonance from other resonances, and that another resonance can be used as an internal reference to reduce the effects of external magnetic field instability, tissue susceptibility and inter-scan tissue movement or deformation. Methods utilizing various magnetic resonance spectroscopy (MRS) techniques, such as single voxel spectroscopy, conventional magnetic resonance spectroscopic imaging (MRSI), echo planar spectroscopic imaging (EPSI) and line scan echo planar spectroscopic imaging (LSEPSI) are discussed.     

Non-invasive MR thermography using the water proton chemical shift.

Among various proton magnetic resonance (MR) parameters, such as longitudinal relaxation time, transverse relaxation time, diffusion coefficient and chemical shift, the chemical shift of water protons is recognized as the most reliable indicator of temperature. The chemical shift is the only frequency-based parameter and is independent of the other parameters, which are measured based on the intensity of the MR signal. In this paper, the basic principle and the recent progress in imaging temperature by spectroscopic techniques using the water proton chemical shift are discussed. The advantages of spectroscopic imaging over phase mapping for measuring temperature are that the former can distinguish water resonance from other resonances, and that another resonance can be used as an internal reference to reduce the effects of external magnetic field instability, tissue susceptibility and inter-scan tissue movement or deformation. Methods utilizing various magnetic resonance spectroscopy (MRS) techniques, such as single voxel spectroscopy, conventional magnetic resonance spectroscopic imaging (MRSI), echo planar spectroscopic imaging (EPSI) and line scan echo planar spectroscopic imaging (LSEPSI) are discussed.     

Surrounding muscle edema detected by MRI is valuable for diagnosis of intramuscular myxoma

We recently experienced 4 cases of intramuscular myxoma and analyzed MRI findings, comparing them with histological ones. Results showed that all tumors were depicted with a homogeneous low signal intensity on T1-weighted images and a markedly high signal intensity on T2-weighted images, findings which are similar to those of cystic lesions like intramuscular ganglions. However, tumors were diffusely and finely enhanced on T1-weighted images with intravenous gadolinium administration. Three cases showed the characteristic fat rim and fat cap. A diffuse edematous lesion demonstrating intermediate signal intensity on T1-weighted images and high signal intensity on T2-weighted images was also found in the adjacent muscle surrounding the tumor in 3 of 4 cases. In this lesion, tumor invasion, diffuse and severe muscle degeneration, blood and lymphatic congestion with exudates, and reactive adipose tissue formation were observed. The present results suggested that for the clinical diagnosis of intramuscular myxoma with MRI examination, the combination of three MRI signs such as homogeneous low signal intensity on T1-weighted mages, markedly high signal intensity on T2-weighted images, and an enhancement effect with contrast medium are important, but the fat rim or fat cap, and the surrounding muscle edema as detected by MRI are also characteristic and allow for a more firm diagnosis. We presume that the diffuse and severe muscle fiber degeneration induced by tumors may cause such specific surrounding muscle edema.     

The detection of bone marrow involvement by lymphoma using magnetic resonance imaging

We used magnetic resonance (MR) to image the bone marrow of 31 patients with lymphoma. Images were obtained of the femoral, pelvic, and vertebral marrow with a 0.15 tesla imaging system using a T1-weighted spin echo sequence (TR600/TE 40). With this pulse sequence, normal marrow produces a high intensity signal that reflects the presence of marrow fat (short T1 relaxation time). We previously reported MR imaging of patients with leukemia in relapse and found a diffusely and symmetrically decreased marrow signal intensity due to the replacement of normal marrow fat by cellular material with a long T1. Unlike leukemia, patients with lymphomatous marrow involvement often had patchy, often discrete, areas of low signal intensity, representing focal marrow infiltration. Five of six patients in this study with lymphoma detected by histologic examination also had marrow lesions seen on MR. An additional four patients had marrow lesions detected by MR that were not detected on initial marrow biopsies; two of these had marrow involvement proven on subsequent biopsies, one had disease isolated to the vertebrae that was never pathologically documented, and one had progression of disease in the marrow documented by MR without biopsy confirmation. These results indicate that marrow involvement with lymphoma can be detected by MR imaging and that MR can complement bone marrow biopsy.     

Magnetic resonance imaging of brain tumors

Magnetic resonance imaging (MRI) has been applied to the diagnosis of brain tumors very widely and MRI is now replacing computed tomography (CT). One of the most important advantages of MRI is influence of multiple tissue and machine parameters on the signal intensities. In addition, capability of imaging in various planes and multislices is another advantage for the brain tumor diagnosis. The coronal image is important when the abnormal side can be compared with the normal side and midline lesions can be easily diagnosed with sagittal imaging. Transverse imaging is important when comparison is made with CT. Many brain tumors show increased signal intensity on T2-weighted images and decreased signal intensity on T1-weighted images and decreased signal intensity on T1-weighted images. The difference of signal intensity in various brain tumors including glioma, meningioma and other important tumors are discussed. MRI is superior to CT in many brain tumors, but poor delineation of calcification and hemorrhage is a disadvantage of MRI.     

脉络膜裂囊肿的影像学诊断

背景与目的：脑部脉络膜裂囊肿属神经上皮性囊肿,临床上不常见。本文通过探讨脉络膜裂囊肿的影像学表现,以期提高对本病的诊断及鉴别诊断水平。方法：回顾性分析20例CT和MRI诊断为脉络膜裂囊肿患者的临床及影像学资料。患者均行CT和MRI检查,其中增强扫描5例。结果：20例患者均为单发病灶．其中右侧13例,左侧7例,病灶均位于两侧脉络膜裂区。CT表现为圆形或类圆形、边缘光滑的脑脊液样低密度灶、增强扫描无强化。MRI检查表现为长T1长T2脑脊液样信号灶,FLAIR为低信号,在各扫描序列中完全与脑脊液信号同步,病灶周围脑实质无明显异常表现。结论：正确认识脉络膜裂囊肿的影像学表现．可避免误诊。CT和MRI均可检出脉络膜裂囊肿,但单纯CT检出定位困难,MRI多方位扫描可作出明确诊断并能够与其他囊性病变相鉴别。     

Contrast-enhanced magnetic resonance imaging of the breast.

Contrast-enhanced magnetic resonance imaging (MRI) of 28 patients with known breast tumors was compared with clinical findings and histopathology, and for 12 of the patients also with mammography. The dynamic measurements performed in 18 patients showed that signal intensity in gradient echo (FFE) images increased rapidly in malignant tumors after contrast injection and reached a plateau level at 1-3 min postcontrast. Fibroadenomas showed slower contrast enhancement continuing throughout the whole examination period of 10 min. The most enhancing parts of the tumors were selected for intensity measurements. The differentiation between malignant and benign tumors in dynamic contrast-enhanced MRI was in accordance with the histopathological findings in all cases. The tumor diameter as measured by MRI showed very good agreement with the size of the tumor specimens. Comparison of tumor size measurements in mammography and MRI showed that MRI had the most accurate correlation to the measured size of the tumor specimens.     

磁共振成像-弥散加权成像诊断良恶性卵巢肿瘤的临床价值

目的 探讨磁共振成像-弥散加权成像(MRI-DWI)诊断良恶性卵巢肿瘤的临床价值.方法 对经手术病理确诊为卵巢占位性病变的100例患者的MRI常规扫描参数及DWI图像表现进行分析.比较良恶性病变的病变最大径、表观扩散系数(ADC)值、肿瘤位置、边界、囊实性、囊壁/分隔、T1及T2信号均匀性,并进行Logis-tic回归...     

腹膜后良性神经源性肿瘤的MRI表现

目的 分析腹膜后良性神经源性肿瘤的MRI表现,以期提高诊断正确率.方法 复习经手术及病理证实并行MRI检查的腹膜后良性神经源性肿瘤23例,包括神经鞘瘤10例,肾上腺外嗜铬细胞瘤8例,神经节细胞瘤及神经纤维瘤各2例,副神经节瘤1例,对肿瘤的部位、大小、形态、边缘及信号特点进行分析.结果 23个肿瘤中位于腹膜后脊柱右侧者18例,左侧4例,椎前腹主动脉与下腔静脉之间1例.肿瘤横断面最大径3.1～14.5 cm,平均6.5cm.肿瘤呈类球形改变的22例,占95.7%,不规则形仅1例,类球形肿瘤中有10例(45.5%)可见病变部分呈鸟嘴样伸入椎间孔或下腔静脉后.肿瘤边界清楚,T2WI可检出包膜者17例(73.9%).T1WI肿瘤均以低信号或等信号为主,其中病灶内混杂高信号影2例.T2WI肿瘤信号多不均匀(19例,占82.6%),内均可见明显高信号区,其中表现为"靶征"8例,占全部病例的34.8%,包括神经鞘瘤5例,神经节细胞瘤2例,神经纤维瘤1例,嗜铬细胞瘤无一例出现"靶征".T2WI表现信号均匀4例.增强扫描不均匀强化19例,T2WI肿物内的明显高信号区出现强化10例(52.6%).T2WI显示"靶征"者增强扫描显示"靶心"强化.增强扫描均匀强化者4例.结论 腹膜后良性神经源性肿瘤的MRI表现有一定特征性,可为肿瘤的鉴别诊断提供依据.     

Magnetic resonance imaging of pelvic endometriosis

Endometriosis is a multifocal disease involving multiple pelvic sites. Although laparoscopy is the elective exam in the study of patients with clinically suspected endometriosis, MR imaging represents a valid noninvasive procedure for the study of areas unapproachable with laparoscopy. On MR imaging, areas of endometriosis over 1 cm in size appear homogeneously hyperintense in T1-weighted images and hypointense in T2-weighted images, while areas of endometriosis less than 1 cm in size appear hyperintense in T1-weighted images and with variable signal in T2-weighted images. Endometriosis may also appear as small cystic lesions, hyperintense in T1-weighted images. While MR imaging has some limitations in the visualization of small endometriotic implants and adhesions, it has the ability to characterize the lesions, to study extraperitoneal locations and the contents of pelvic masses. The reliability of MR imaging findings of endometriosis and the assessment of pelvic organ involvement is important for guiding subsequent laparoscopy.     

3T MRI in evaluation of asbestos-related thoracic diseases - preliminary results

Background

3T high-field magnetic resonance imaging (MRI) scanners have recently become available for the clinical use and are being increasingly applied in the field of whole-body imaging and chest imaging as well. The aim of this study was to evaluate the diagnostic potential of 3 T MRI as a complementary imaging modality to CT in detecting the pathological changes of asbestos-related thoracic diseases.

Patients and methods

Fifteen patients with the asbestos-related thoracic disease were scheduled for 3T MRI. Five had a benign form of the disease and 10 had malignant pleural mesothelioma (MPM). From the patients with a benign form of the disease their last CT examination in digital form was acquired and patients with MPM were scheduled for CT examination with contrast media. The protocol of MR imaging consists of T2-weighted cardiac-gated breath-hold turbo spin echo (TSE) sequences in coronal, sagittal and axial plane and T1-weighted cardiac-gated breath-hold TSE black blood in axial plane. In T2-weighted sequences in axial plane, fat saturation was also used. CT examinations were obtained with the administration of the contrast medium from lung apices to the lower end of the liver. Images of 5 mm (mediastinum window) and 3 mm (lung window) in axial plan were reconstructed. MRI signal intensity of lesions and adjacent muscles on Syngo MultiModality Work Place were measured.

Results

Compared to muscles pleural plaques appeared hypo-intense to iso-intense on T1 weighted images (in 100%) and also hypo-intense on T2 fs-weighted images (in 100%). MPM appeared inhomogeneous hypo-intense to iso-intense on T1-weighted and hyperintense on T2 fs-weighted images in all patients (100%).

Conclusions

These preliminary results pointed out that MRI was equal or even better compared with CT examination for detecting possible malignant potential of pleural changes in the asbestos-related pleural disease, using signal intensity measurements of T2 fs-weighted images. The 3T MRI enabled the accurate determination of chest pathology and it could be used for imaging of patients with the asbestos-related thoracic disease. MRI is particularly valuable because a patient is not exposed to the harmful radiation which is important if imaging methods are used repeatedly, like in screening programs or in monitoring of treatment results. This finding turned us to propose 3T MRI imaging technique as a non-ionizing imaging method for the follow-up of patients with the isolated pleural form of the asbestos-related disease.     

Multiple pancreatic metastases from clear cell renal carcinoma: Diagnosis with chemical shift magnetic resonance imaging before surgery

We present a case in which multiple pancreatic tumours were diagnosed as metastatic clear cell renal carcinomas with chemical shift MRI (CSI) before surgery. Radiologists may be unable to recognize the loss of intensity on CSI macroscopically. We believe that it is useful to make subtraction images and calculate signal intensity on CSI, even if the lesions are multiple metastatic tumours.     

Spontaneous regression of multicentric pilocytic astrocytoma with CSF dissemination in an adult

We present a case of spontaneous regression of multicentric pilocytic astrocytoma with cerebrospinal fluid (CSF) dissemination without neurofibromatosis type 1 (NF1) in an adult, the first such case reported. Magnetic resonance imaging (MRI) showed multiple low signal intensity lesions on T1-weighted images and high signal intensity areas on T2-weighted images in the bilateral thalamus, basal ganglia and midbrain. Contrast-enhanced MRI revealed that small, enhanced lesions were seen in the basal ganglia and the pineal region. Neuroendoscopic biopsy and third ventriculostomy were performed. Intraoperative findings demonstrated CSF dissemination. Histologically, the specimens showed pilocytic astrocytoma. Serial MRIs showed regression of the tumor without any additional treatment. The clinical features of spontaneous regression of pilocytic astrocytoma are discussed.     

Usefulness of magnetic resonance imaging with dynamic contrast enhancement and fat suppression in detecting a pancreatic tumor

The purpose of this study was to compare the value of dynamic magnetic resonance imaging (MRI) and fat suppression in detecting a pancreatic tumor. The subjects were 19 patients with invasive ductal adenocarcinoma and six patients with islet cell tumor where diagnosis was established pathologically. Breath-hold gradient echo images, breath-hold gradient echo images with fat suppression and breath-hold gradient echo images with dynamic enhancement at 1.5 T were obtained for all patients. The efficacies of these three imaging techniques were compared by calculating the contrast-to-noise ratio, as indicative of conspicuousness between a tumor-affected and a normal pancreas. As for adenocarcinoma, our results indicated that the usefulness in detecting the tumor was high, decreasing in the order dynamic contrast images > fat suppression images > plain images, and that the difference between any two of these three types of image was statistically significant. On the other hand, these imaging techniques showed no statistically significant difference in detecting islet cell tumors. In conclusion, dynamic MRI is the best method for detecting pancreatic adenocarcinoma. As the fat suppression technique has the advantage of being non-invasive, this method is suitable for screening studies of pancreatic adenocarcinoma. However, no advantage was recognized in using the fat suppression technique for detecting an islet cell tumor in comparison with plain MRI.