MR imaging of the ovaries: normal appearance and benign disease

MR imaging enables a physician to make an accurate diagnosis of various benign adnexal masses and helps to obviate unnecessary surgery.     

Pediatric musculoskeletal MR imaging

In a review of the indications and uses for magnetic resonance (MR) imaging of the pediatric musculoskeletal system, MR evaluation of conditions unique to the pediatric musculoskeletal system were emphasized. Indications for MR imaging of the pediatric musculoskeletal system include evaluation of bone marrow, neoplastic processes, and periarticular disorders.     

MR imaging of benign and malignant lesions in the buccal space

OBJECTIVES: To evaluate MRI characteristics of buccal space lesions and to discuss the sensitivity of MRI in predicting malignancy of those lesions. METHODS: Thirty patients with malignant (n=7) or benign (n=23) lesions originating in the buccal space were reviewed retrospectively. MR images were assessed for the margins, internal architecture, signal intensity of lesions and their relation to the surrounding structures. RESULTS: Two cases of soft tissue sarcoma were shown as ill-defined masses with infiltration into adjacent muscles and bone. On the other hand, all tumors of minor salivary gland origin, whether malignant (n=4) or benign (n=2), were well-defined and confined within the buccal fat pad without infiltration into surrounding structures. All haemangiomas (n=9) had very high T2-weighted signal intensity. Three out of them contained signal voids on all sequences thought to represent phleboliths, a finding strongly suggestive of the diagnosis. Inflammatory lesions were characterized by the presence of edema in the surrounding fat. When ill-defined margins, infiltration into muscles and bone destruction were used as the criteria for the malignancy, only two out of seven malignant tumors were correctly diagnosed (sensitivity 29%). CONCLUSIONS: Although MR imaging was useful in demonstrating the extent of buccal space lesions, its diagnostic value in predicting malignancy was very limited. It was especially true for malignant tumors of minor salivary gland origin, which were typically seen as well-defined masses without infiltration into surrounding structures on MRI.     

Lymphocytic vasculitis mimicking aggressive multifocal cerebral neoplasm: mr imaging and MR spectroscopic appearance

We present a case of multifocal enhancing lesions confined to the right cerebral hemisphere that mimicked diffuse neoplasm. MR spectroscopy revealed not only minimal elevation of the choline peak, but also marked elevation of the glutamate and glutamine peaks, findings that are more suggestive of an inflammatory process. Biopsy showed lymphocytic vasculitis, a rare variant of primary angiitis of the CNS. Following appropriate medical therapy, MR imaging demonstrated complete resolution of the lesions.     

Multiple myeloma: appearance at MR imaging.

Magnetic resonance (MR) imaging examinations of the lumbar spine and clinical and laboratory findings in 32 patients with multiple myeloma were reviewed. On T1-weighted images, signal intensity (SI) of the vertebrae approximated that of muscle in 14 cases and was intermediate (between the SIs of muscle and fat) in 18. Definite foci of decreased SI were seen in eight cases (25%), and foci of increased SI, representing fatty infiltration, were seen in 12 (38%). On T2-weighted images, SI approximated that of muscle in 17 cases and was intermediate in 15. Definite foci of increased SI were seen in 17 (53%). Of 38 vertebral compression fractures (including 18 in nine additional patients), foci of abnormal SI consistent with tumor on either T1- or T2-weighted images were seen in 19 cases (50%). There was no correlation between MR imaging findings and laboratory or bone marrow findings. Foci of presumed tumor were better or exclusively shown on T2-weighted images in 11 of 17 patients (65%) with identifiable focal disease. Other suggestions of multiple myeloma on T1-weighted images may be the absence of fatty replacement or a generalized decrease in SI.     

Role of diffusion-weighted MR imaging in assessing malignant versus benign skull-base lesions

Purpose

This study was done to assess the role of diffusion-weighted magnetic resonance (MR) imaging in assessing malignant versus benign skull lesions.

Materials and methods

A retrospective analysis was undertaken of 45 patients (26 male, 19 female; age range 14?C68 years, mean age 39 years) with skull-base lesions. Diffusion-weighted MR images were acquired with a bfactor of 500 and 1,000 s/mm² using single-shot echoplanar imaging. Apparent diffusion coefficient (ADC) maps were reconstructed, and the ADC value of the lesion was calculated.

Results

The mean ADC value of malignant tumours was (1.002±0.21)×10^?3 mm²/s and that of benign tumours was (1.63±0.29)×10^?3 mm²/s. There was a statistically significant difference (p=0.001) in the ADC value of malignant skull-base tumours versus benign lesions. Selection of (1.3)×10^?3mm²/s as a threshold value of ADC for differentiating benign from malignant tumours yielded the best result, with an accuracy of 94%, sensitivity of 94%, specificity of 93%, positive predictive value of 93%, negative predictive value of 94% and area under the curve of 0.932.

Conclusions

We conclude that diffusion-weighted MR imaging is a promising, noninvasive approach that can be used to characterise skull-base lesions in that it can help differentiate malignant tumours from benign lesions and evaluate the pathological grading of malignant tumours.     

髋部疼痛常见病的磁共振表现

目的:探讨髋部疼痛病因的MRI影像学表现与鉴别诊断,为正确诊断髋部疼痛提供参考依据。方法:收集我院2005年8月～2009年7月期间,以髋部局部疼痛为主要临床症状的325例患者MRI资料。回顾性分析导致髋部局部疼痛的发病部位,病因及其MRI表现,探讨MRI对髋部疼痛的鉴别诊断价值。结果:引起髋部局部疼痛病因可来源于多个部位,包括骨盆、骶髂关节、腰椎等病变以及腹壁、泌尿生殖道、腹膜后间隙病变。其致病原因亦复杂多变,包括肌肉、肌腱软组织损伤,软骨损伤,关节脱位,骨折,梨状肌综合症,髋部弹响综合症,感染,关节游离体,骨性关节炎,股骨头无菌坏死,骨肿瘤,软组织肿瘤,泌尿系结石及椎间盘突出等多种疾病。结论:成人髋关节疼痛可由多种不同病因引起,可以直接与髋关节有关,也可以与髋关节周围结构有关,甚至与髋关节无关的结构如腰椎,腹膜后疾病。对于髋部疼痛,应根据临床表现选择适当影像学检查,综合考虑各种病因进行诊断。     

MR动态增强扫描时间一信号强度曲线在骨骼肌肉系统肿瘤定性诊断中的价值

目的 探讨动态增强MRI时间一信号强度曲线(TIC)上升段最大斜率值和曲线类型在骨骼肌肉系统良、恶性肿瘤鉴别中的作用.方法 采用多时相增强快速采集梯度同波序列,对93例骨骼肌肉系统肿瘤进行MR动态增强扫描,在斜率图上选取ROI,经Functool软件后处理,得到TIC,并将曲线分为Ⅰ、Ⅱ、Ⅲ型,计算曲线上升段最大斜率值.以病理结果为金标准,对TIC类型在良、恶性肿瘤中的分布差异和曲线的上升斜率值进行χ2检验或t检验.结果 49例恶性肿瘤中,37例为I型曲线,12例为Ⅱ型曲线;44例良性肿瘤中,26例为Ⅰ型曲线,7例为Ⅱ型曲线,11例为Ⅲ型曲线,曲线类型在良、恶性肿瘤中的分布差异具有统计学意义(χ2:14.008,P<0.01).良、恶性肿瘤曲线上升斜率值分别为6.80±3.35和6.80±2.71,差异无统计学意义(t=0.008,P＞0.05).与形态学表现相结合,应用TIC类型对骨骼肌肉系统恶件肿瘤定性诊断的敏感度为100%,特异度为50%,阳性预测值为78%,阴性预测值为100%,准确度为82%.结论 TIC类型结合形态学表现,能够提高MRI对骨骼肌肉系统肿瘤良、恶性鉴别的能力.     

MRI扩散加权成像对乳腺良恶性病变的诊断

目的:探讨磁共振扩散加权成像(DWI)对乳腺良恶性疾病的诊断价值。方法:回顾性分析40例经病理确诊的乳腺疾病,其中良性病变22个,恶性病变18个;均行DWI检查,测定病灶区表观扩散系数(ADC值),与正常组织进行比较,计算相对表观扩散系数(rADC值),应用SPSS 16.0软件比较其平均值,并以病理结果为金标准,作ROC曲线,求其最佳诊断阈值。结果:良性病变及恶性病变的ADC值分别为(1.55±0.35)×10-3和1.00±0.18)×10-3 mm2/s,其rADC值分别为(0.82±0.19)和(0.52±0.08)。良恶性病变组间均有统计学差异,以ADC值及rADC值为诊断标准作受试者工作特征曲线(ROC曲线),其中ADC值的曲线下面积(AUC)为(0.927±0.04),rADC值的AUC为(0.965±0.03),诊断阈值分别为1.17×10-3 mm2/s、0.66,相应敏感度及特异度分别为(90.9%、88.9%)和(95.5%、94.4%),rADC值的AUC、敏感度及特异度均高于ADC值。结论:DWI对乳腺良恶性病变的的诊断具有重要作用,其中rADC值有更好诊断效能。     

良性肝细胞病变的高b值扩散加权MR成像:定性与定量分析

目的分析良性肝细胞病变在高b值扩散加权MR成像中的信号强度(SI),并比较局灶性结节增生(FNH)与肝细胞腺瘤(HCA)的表观扩散系数(ADC)。材料与方法本回顾性研究获机构审查委员会批准,免除知情同意。入选标准为诊断FNH或HCA的连续病人,接受3种b值(0、150、     

磁共振扩散加权成像在乳腺良恶性病变中的诊断价值

目的探讨磁共振扩散加权成像在乳腺良恶性病变中的诊断价值。方法收集我院2010年2—8月经手术病理证实或穿刺活检证实的50例乳腺癌患者和50例乳腺良性病变患者。DWI扫描b值分别为400、600、8001、000 s/mm2,测量病灶区域的ADC值,并比较各组之间的差异。结果 b值分别为400、6008、001、000时乳腺癌及良性病变的ADC值,恶性组ADC值明显低于良性组(P<0.05)。四组不同b值的良恶性病变分别做ROC曲线,以b=1 000 s/mm2时,AUC最大,诊断价值最高,以ADC值为1.23×10-3mm2/s作为良恶性病变的诊断阈值,敏感性为90.0%,特异性为89.8%,准确性为89.9%。结论 DWI结合ADC值测量,对乳腺良恶性病变的鉴别诊断具有较高的临床应用价值。     

MR imaging after surgery for musculoskeletal neoplasm

Magnetic resonance (MR) imaging is the current radiologic method of choice for both detecting recurrent musculoskeletal neoplasm after surgical resection and defining its anatomic extent within soft tissue and bone. Various factors (such as the presence of surgical hardware and postsurgical seromas, hematomas, edema, scarring, and anatomic distortion) complicate the interpretation of postoperative MR imaging in these patients. By optimizing the MR imaging protocol, integrating relevant clinical and pathologic information (such as the date and extent of the most recent surgery and the histologic type and grade of the original tumor) during interpretation of the images, and being familiar with the typical manifestations of postsurgical changes and recurrent musculoskeletal tumors, the radiologist can maximize his ability to help guide patient management effectively.     

MR imaging appearance of intraperitoneal gelatin sponge in mice.

Intraperitoneal gelatin sponge can mimic a mass lesion on magnetic resonance (MR) images. To determine the MR imaging characteristics of gelatin sponge over time, a 15 x 10 x 4-mm piece of gelatin sponge soaked in saline was surgically implanted in the peritoneal cavity of 14 mice. Two mice underwent a sham operation. Contiguous axial spin-echo images of the abdomen were obtained with T1-weighted, spin-density, and T2-weighted sequences preoperatively and over a 6-week period postoperatively. Gelatin sponge initially appears as a heterogeneous mass of low signal intensity on T1-weighted images and increasing intensity on spin-density and T2-weighted images, containing multiple round foci of very low signal intensity, attributable to air, at all sequences. Over time, signal intensity further increases and becomes more homogeneous on spin-density and T2-weighted images, although foci of air persist to 3 weeks. By 2-4 weeks, the mass is no longer discrete. Foci of air should help differentiate gelatin sponge from tumor and add gelatin sponge to the differential diagnosis of abscess.     

MR imaging of the stellate ganglion: normal appearance.

The stellate ganglion has not previously been identified by imaging techniques. MR imaging shows the stellate ganglion at the thoracic inlet adjacent to the neck of the first rib, lateral to the longus colli muscle and posterior to the vertebral artery. Although its shape varies somewhat, it can be identified consistently in normal persons.     

Breast MR imaging: computer-aided evaluation program for discriminating benign from malignant lesions

PURPOSE: To retrospectively determine the sensitivity of kinetic features measured with computer-aided evaluation at breast magnetic resonance (MR) imaging in discriminating benign from malignant lesions, with histopathologic findings used as the reference standard. MATERIALS AND METHODS: Institutional review board approval was obtained for this HIPAA-compliant study. Informed consent was waived. Suspicious breast lesions visible only at MR imaging and in which biopsy had been performed with MR imaging guidance were retrospectively evaluated with a computer-aided evaluation program. Computer-generated kinetic features for each lesion were recorded, and those of benign and malignant lesions were compared. Features analyzed included the presence or absence of computer-aided evaluation "threshold enhancement" at 50% and 100% minimum thresholds; degree of initial peak enhancement; and enhancement profiles composed of lesion percentages of washout, plateau, and persistent enhancement. The Fisher exact test and Student t test were used to assess differences in these analyses. RESULTS: One hundred fifty-four consecutive lesions (41 malignant, 113 benign) in 125 women (age range, 27-86 years; mean age, 52 years) were evaluated. The presence of threshold enhancement at computer-aided evaluation was sensitive for malignancy, with 38 of 41 (93%) malignant lesions demonstrating enhancement at both the 50% and 100% thresholds. Absence of threshold enhancement at computer-aided evaluation helped improve the discrimination between benign and malignant lesions when compared with that at initial interpretation by the radiologists. False-positive rates were reduced by 8.8% at the 50% enhancement threshold (not significant) and by 23.0% at the 100% enhancement threshold (P=.02) when compared with that at initial interpretation. Analyses of initial peak enhancement values and enhancement profiles did not demonstrate further improvements in lesion discrimination. CONCLUSION: The use of computer-aided evaluation for breast MR imaging significantly helped improve the discrimination of benign from malignant lesions when compared with that at initial interpretations by radiologists.     

Malignant versus benign mediastinal lesions: quantitative assessment with diffusion weighted MR imaging

Objectives  

We aimed to evaluate the performance of diffusion-weighted magnetic resonance imaging in differentiating malignant from benign mediastinal lesions.     

MR diffusion imaging in mediastinal masses the differentiation between benign and malignant lesions

Background

Diffusion-weighted imaging is a fundamental tool integrated in MR protocols useful in differentiating benign from malignant mediastinal masses, assessing mediastinal lymphadenopathy and investigating central bronchogenic carcinoma. This method is an excellent alternative to CT or PET/CT in the investigation of mediastinal masses. Current applications of diffusion MRI in malignancies include monitoring the treatment response and detecting recurrent cancer.