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.     

Characterization of bone and soft-tissue tumors with in vivo 1H MR spectroscopy: initial results

PURPOSE: To determine if in vivo detection of choline by using hydrogen 1 (1H) magnetic resonance (MR) spectroscopy with dynamic contrast material-enhanced MR imaging can help differentiate between benign and malignant musculoskeletal tumors. MATERIALS AND METHODS: MR imaging was performed in 36 consecutive patients with bone and soft-tissue tumors larger than 1.5 cm in diameter. Examinations were performed at 1.5 T with a surface coil appropriate for the location of the lesions. Single-voxel 1H MR spectroscopy was performed by using a point-resolved spectroscopic sequence with echo times of 40, 135, and 270 msec. The volume of interest within lesions was positioned on the areas of early enhancement (<8 seconds after arterial enhancement) according to the findings of dynamic contrast-enhanced MR imaging with subtraction. The criterion for determining whether choline was present in a lesion was a clearly identifiable peak at 3.2 ppm in at least two of the three spectra acquired at echo times. MR spectroscopic results and histopathologic findings were determined in blinded fashion and compared with kappa statistics. P <.001 was considered to indicate a significant difference. RESULTS: Choline was detected in 18 of 19 patients with malignant tumors and in three of 17 patients with benign lesions. The three benign lesions included one perineurioma, one giant cell tumor, and one abscess. Choline was not detected in 14 patients with benign lesions nor in one patient with a densely ossifying low-grade parosteal osteosarcoma. In vivo 1H MR spectroscopy characterized bone and soft-tissue tumors, resulting in a sensitivity of 95%, specificity of 82%, and accuracy of 89% (P <.001). CONCLUSION: Choline can be reliably detected in large malignant bone and soft-tissue tumors by using a multiecho point-resolved spectroscopic protocol. 1H MR spectroscopy can help differentiate malignant from benign musculoskeletal tumors by revealing the presence or absence of water-soluble choline metabolites.     

Salivary gland tumors: diagnostic value of gadolinium-enhanced dynamic MR imaging with histopathologic correlation

PURPOSE: To evaluate the diagnostic value of gadolinium-enhanced dynamic magnetic resonance (MR) imaging of salivary gland tumors and correlate the MR imaging and histopathologic findings. MATERIALS AND METHODS: Thirty-three salivary gland tumors in 29 patients were examined preoperatively at gadolinium-enhanced dynamic MR imaging. There were 22 benign and 11 malignant tumors. Dynamic contrast material-enhanced MR images were obtained for 5 minutes. Time of peak enhancement (T(peak)) and washout ratio (WR) were determined from time-signal intensity curves (TICs). Microvessel count and cellularity-stromal grade were evaluated histopathologically. The strengths of correlations between T(peak) and microvessel count and between WR and cellularity-stromal grade were statistically analyzed. Statistical analysis was also performed to determine whether any differences among the various histopathologic tumor types existed [corrected]. In a validation study, 13 salivary gland tumors in 13 patients were examined consecutively. RESULTS: At a T(peak) of 120 seconds, malignant tumors could be differentiated from pleomorphic adenomas but not from Warthin tumors. A WR of 30%, however, enabled differentiation between malignant and Warthin tumors. Classification of TICs on the basis of a T(peak) of 120 seconds and a WR of 30% had high sensitivity (91%) and specificity (91%) in the differentiation of benign and malignant tumors. Correlations between T(peak) and microvessel count (P <.0001, rho = -0.800) and between WR and cellularity-stromal grade (P =.0105, rho = 0.572) were significant. The validation study also yielded high sensitivity (100%) and specificity (80%) in the differentiation between benign and malignant tumors. CONCLUSION: Gadolinium-enhanced dynamic MR imaging is useful for differentiating benign from malignant salivary gland tumors.     

Prospective evaluation of pancreatic tumors: accuracy of MR imaging with MR cholangiopancreatography and MR angiography

PURPOSE: To prospectively assess accuracy of magnetic resonance (MR) imaging, MR cholangiopancreatography (MRCP), and MR angiography in patients suspected of having pancreatic tumors. MATERIALS AND METHODS: Sixty-six patients suspected of having pancreatic tumors underwent MR imaging (unenhanced and contrast material-enhanced MR, MRCP, and contrast-enhanced MR angiography). Two blinded readers prospectively analyzed the images by consensus, and results were correlated with surgery, biopsy, or follow-up findings. Results were tabulated in two-by-two tables. RESULTS: MR assessment of pancreatic lesion status (differentiation of benign vs malignant) resulted in 60 correct diagnoses (accuracy, 91%), and six (10%) false diagnoses. Among histologically proved malignant tumors, MR imaging yielded correct diagnoses in 42 of 44 patients (sensitivity, 95%; 95% CI: 85%, 99%), whereas 18 of 22 patients with benign findings were classified correctly. At MR imaging, findings in four patients with chronic pancreatitis were wrongly categorized as malignant tumors (specificity, 82%; 95% CI: 60%, 95%), and in one patient, a distal common bile duct carcinoma was not detected. In no patient with pancreatic adenocarcinoma was this tumor misdiagnosed as benign. In patients with malignant tumors who underwent resection, local-regional tumor growth and vascular infiltration were accurately classified in 89% and 94%, respectively. MR imaging depicted histologically proved synchronous hepatic metastases in 82%. The positive and negative predictive values for cancer nonresectability were 90% and 83%, respectively, and the accuracy, sensitivity, and specificity were 85%, 69%, and 95%, respectively. CONCLUSION: Unenhanced and contrast-enhanced MR imaging with MRCP and MR angiography offers potential as a noninvasive tool for assessment of patients suspected of having pancreatic tumors.     

MR动态增强鉴别良恶性骨肿瘤及肿瘤样病变的价值

目的探讨磁共振动态增强时间-信号强度曲线(time-signal intensity curve,TIC)和动态强化参数早期动态增强的斜率值(Slope)、边缘-中心向心强化程度比(Rrim-center)在鉴别良、恶性骨肿瘤及肿瘤样病变的价值。资料与方法选择临床资料完整的骨肿瘤及肿瘤样病变患者61例行动态增强扫描,利用工作站配置的MeanCurve分析软件直接得到病变实质、邻近肌肉及相同层面的动脉TIC,测量指标包括TIC类型、Slope、Rrim-center。统计学分析结果以P<0.05为差异有统计学意义。结果 61例良恶性骨肿瘤TIC类型:23例良性骨肿瘤及肿瘤样病变中,I型0例,Ⅱ型7例(30.4%),Ⅲ型13例(56.5%),Ⅳ型3例(13.0%);38例恶性骨肿瘤中,I型11例(28.9%),Ⅱ型17例(44.7%),Ⅲ型10例(26.4%),Ⅳ型0例;良、恶性骨肿瘤TIC类型分布差异有统计学意义;TIC取I、Ⅱ型曲线为恶性诊断标准,诊断恶性肿瘤的敏感性为73.68%,特异性为69.57%,准确性为72.13%,阳性预测值为80%,阴性预测值为61.54%。动态增强参数比较,良性骨肿瘤Slope...     

动态增强MRI对软组织肿块良、恶性的鉴别诊断价值

目的 评价动态增强MRI对软组织肿块和肿瘤样病变的良、恶性的鉴别价值。方法 对30例经病理证实的软组织肿块进行动态增强扫描，其中恶性肿瘤11例，良性肿块19例。将感兴趣区(ROI)的信号强度绘制成时间-信号强度曲线(TIC)，并分别计算其0．5min斜率值。结果 30例软组织肿块的TIC分为3型，12例表现为I型曲线，其中10例为恶性肿瘤，2例为良性肿瘤；12例表现为Ⅱ型曲线，其中11例为良性肿块，1例为恶性肿瘤；6例表现为Ⅲ型曲线，均为良性肿块。11例恶性肿瘤中，10例病变的0．5min斜率值大于0．0057；19例良性肿块中，17例0．5min斜率小于0．0057；良、恶性肿瘤的TIC斜率值之间存在显著性差异，Logistic回归分析病变良、恶性和斜率值有相关性。以0．5min斜率值0．0057作为鉴别肿块良恶性的阈值，判断肿块良、恶性的敏感性为90．9%，特异性为89．4％，阳性预测值为83．3％，阴性预测值为94．4％。结论 动态增强MRI可以较准确地预测肿瘤病变的良、恶性。     

动态增强MRI对眼眶病变诊断及鉴别诊断的价值

目的运用动态增强MR技术，分析病变的强化特点，以提高对不同眼眶病变的认识，尤其是不同良性肿瘤及恶性肿瘤的强化特点，进而提高MRI的诊断价值。方法共41例，均为单发病灶，均行MR检查，术后均得到病理证实。其中良性肿瘤和类肿瘤病变3l例，恶性肿瘤病变10例。使用1．5T超导MR机，头颅线圈采集。MR平扫包括：横断面T1WI、T2WI及T1WI矢状和冠状面扫描。层厚4mm。增强检查为使用对比剂后立即连续动态扫描，以观察病变的动态变化状况。对所测得的平扫及动态增强信号强度值（前、后），计算其强化率（E％）并得到时间-密度曲线（TIC），并进行统计学分析。结果（1）良恶性肿瘤第1分钟内平均强化率（E1％）比较：恶性肿瘤的E1％〉60％，而良性肿瘤的E1％〈60％，二者差异有统计学意义（P〈0．05）；（2）27例良性肿瘤除脑膜瘤外，绝大多数（88．9％，24例）强化为线型；（3）10例恶性肿瘤和3例脑膜瘤为平台型强化。（4）3例炎性假瘤和1例肉芽肿病变，表现为流出型。（5）12例海绵状血管瘤有特殊的强化模式，表现为局部点状和小结节状强化，然后逐步向全肿瘤扩展。结论动态增强MR检查，对鉴别良恶性肿瘤有明显意义；对鉴别肿瘤和炎症也可提供重要的诊断依据；少数病种，如海绵状血管瘤有特殊的强化模式。     

动态增强MRI时间信号强度曲线在卵巢良恶性肿瘤鉴别中的价值

目的探讨动态增强MRI时间信号强度曲线(TIC)鉴别卵巢肿瘤良恶性的价值。方法收集2016年1月—2017年8月间于我院超声检查发现盆腔附件肿块的71例女性病人,年龄14～78岁,中位年龄52岁。所有病人行MRI常规及动态增强检查后经手术获得病理结果。利用工作站在肿块实性区和正常子宫外肌层设置兴趣区获取TIC,以子宫外肌层强化曲线为基准,对卵巢肿块实性区的TIC类型进行校正,分析曲线类型与良恶性卵巢肿瘤的关系。采用χ~2检验比较良恶性肿瘤间3种TIC类型差异。结果 71例病人中包括卵巢恶性肿瘤40例,良性肿瘤26例,交界性肿瘤5例。上述3种肿瘤的TIC类型的差异有统计学意义(P0.05)。良性肿瘤以Ⅰ型TIC为主(73.1%),恶性肿瘤以Ⅲ型TIC为主(77.5%)。MRI+TIC鉴别肿瘤良恶性的敏感度、特异度、阳性预测值和阴性预测值较单独常规MRI检查各指标均有不同程度提高。结论动态增强MRI及其TIC对卵巢良恶性肿瘤具有重要的鉴别诊断价值。     

Gradient-echo perfusion imaging of musculoskeletal abnormalities with contrast-enhanced two-dimensional fat-saturation FLASH

The objective of this study was to evaluate the utility of MR perfusion imaging of various musculoskeletal lesions with a contrast-enhanced two-dimensional fat saturation fast low angle shot (FLASH) sequence and to assess the potential of this technique for distinguishing malignant from benign conditions. Thirty-six musculoskeletal lesions were studied at 1.5 T. The signal intensity of the lesions, adjacent artery, muscle, bone marrow, and fat were plotted against time. The time to peak enhancement, time to maximum signal intensity, percent enhancement, rate of peak enhancement, and rate of enhancement parameters were calculated. Because of a significant overlap between malignant and benign conditions, accuracy rates were lower than reported previously. The best parameter based on these values was the rate of peak enhancement (sensitivity, 84.6%; specificity, 65.2–66.6%; positive predictive value, 57.8–68.7%). Fat saturation gradient-echo MR perfusion imaging allows for a rapid assessment of the vascularity of musculoskeletal pathology; however, a significant overlap persists between malignant neoplasms and several benign conditions.     

经阴道增强超声造影鉴别诊断附件区良、恶 性包块的临床价值

目的:探讨超声造影对附件良、恶性包块鉴别诊断的价值.材料和方法:观察分析69例附件区良、恶性包块的超声造影表现及灌注特点.结果:恶性肿瘤26例均有增强显示,其灌注模式主要为快速整体、非均质或树枝状高增强(24/26).良性肿块39例,其中囊性病灶24例,囊壁增强模式均为环状、半环状增强(5例囊腔内分隔或乳头突起呈轻度增强);实性包块15例,均有增强显示,10例卵巢肿瘤中8例表现为内部点状低增强,5例宫旁浆膜下肌瘤呈先环状增强,后逐渐向内部充填,或呈周边轻度点状增强.良、恶性两组间增强模式存在显著性差异(P<0.0001).4例卵巢交界性肿瘤呈渐进性或较快速非均质增强.结论:超声造影对鉴别诊断附件区良、恶性包块有较高的价值.     

胸膜局灶性病变动态增强MRI的研究

目的评价MR T2W I和增强检查对胸膜局灶性病变的诊断价值。方法本组31例胸膜局灶性病变均经手术或穿刺活检细胞病检或临床追踪证实。其中恶性肿瘤16例,良性病变15例。MR动态增强扫描后在工作站上比较信号强度和增强形态,并将感兴趣区(RO I)的信号强度绘制成时间-信号强度曲线(TIC),分别计算其0.5 m in斜率值。结果31例胸膜局灶性病变在T2W I平扫的表现上良恶性比较差异有统计学意义(P均<0.05)。本组TIC可分为3型,Ⅰ型17例(恶性肿瘤14例,良性病变3例);Ⅱ型4例(恶性肿瘤2例,良性病变2例);Ⅲ型10例(均为良性病变)。16例恶性肿瘤中14例病变的0.5 m in斜率值>0.00227;15例良性病变中8例病变的0.5 m in斜率值<0.00227;良恶性病变的TIC斜率值之间存在显著性差异。以0.5 m in斜率值0.00227作为鉴别胸膜局灶性良恶性的阈值,31例病变中22例诊断准确,敏感度为87.5%,特异度为53.3%。结论以病灶信号特点、形态、曲线类型或斜率值等判别胸膜病灶的良恶性,有一定的参考价值。     

脾肿瘤的CT诊断及鉴别诊断

目的探讨脾肿瘤CT表现和鉴别诊断价值。方法52例脾肿瘤均行CT平扫 增强检查,其中手术及穿刺活检病理证实27例,征象典型及病史明确25例。结果脾良性肿瘤18例,恶性肿瘤34例。良性肿瘤表现为脾脏内单发或多发,多数大小不等低密度结节病变,1例血管瘤为等密度。血管瘤及淋巴管瘤可显示点状或小片状钙化。增强扫描,血管瘤显示延迟均匀强化特点,淋巴管瘤内间隔可轻度强化。脾囊肿无强化。脾脏恶性肿瘤多较大,密度不均匀,增强扫描不均匀强化。脾淋巴瘤表现为脾肿大或多发结节样低密度病变,增强扫描强化不明显。结论CT是诊断脾肿瘤的主要检查方法,结合临床及B超检查,多可做出诊断。     

Dynamic high-spatial-resolution MR imaging of suspicious breast lesions: diagnostic criteria and interobserver variability

OBJECTIVE: Our study was undertaken to develop diagnostic rules and to assess the reproducibility of dynamic and morphologic parameters for the characterization of suspicious breast lesions using dynamic high-spatial-resolution MR imaging. MATERIALS AND METHODS: Fifty-seven patients with suspicious mammographic or palpable findings underwent preoperative contrast-enhanced MR imaging of the breast using a three-time-point method of acquisition. Each lesion was prospectively analyzed by two independent radiologists for morphologic and visual dynamic enhancement characteristics. A classification and regression tree was used to examine the optimal order, cutoff points, and combination of imaging parameters to build a diagnostic rule separating benign from malignant lesions using histopathology findings as the standard of reference. Kappa statistics were used to determine observer variability. RESULTS: Among 23 benign and 34 malignant lesions (12 invasive, three ductal carcinoma in situ, and 19 mixed cancer), margin morphology (p = 0.001) and enhancement pattern (p = 0.001) were the most significant MR imaging findings for lesion characterization. Focal mass lesions were classified as malignant when spiculated margins or both the washout enhancement pattern and "nonsmooth" margins were present. Interobserver agreement was almost perfect for washout pattern and substantial for margin assessment. In the limited population tested retrospectively, the diagnostic rule yielded a sensitivity and positive predictive value of 97% each and a specificity and negative predictive value of 96% each. CONCLUSION: The washout enhancement pattern combined with lesion margin assessment on dynamic contrast-enhanced high-resolution MR imaging of the breast allows reproducible lesion characterization and may be a highly specific diagnostic tool.     

MR dynamic enhancement of breast lesions: high temporal resolution during the first-minute versus eight-minute study

PURPOSE: To investigate the value of the early phase of MR enhancement of breast lesions. METHOD: To study 63 breast lesions (size 5-45 mm in diameter) in 56 patients, whole-breast and lesion-targeted precontrast T1 -weighted gradient-echo 2D sequences were acquired. After intravenous injection of Gd-DTPA (0.1 mmol/Kg), four targeted scans, each every 15 seconds during the first minute (1-m), and seven whole-breast scans, each every minute up to 8 minutes (8-m), were performed. The subtraction technique was used, and percent enhancement curves were obtained. The final diagnosis was obtained by histology for 36 lesions, including 28 malignancies, and by fine-needle aspiration cytology and at least 1-year negative follow-up for the remaining 27 benign lesions. RESULTS: Significant differences in enhancement between malignant and benign lesions were found using both techniques (p<0.0001). However the ratio between the median enhancement of malignant lesions and that of benign lesions was 6.7 (15 s), 4.8 (30 s), 4.6 (45 s), and 3.8 (60 s), descending from 4.3 to 2.5 from the second to the eighth minute. The overlap between the malignant and benign curves was 9% of the malignant range with the 1-m technique, and 50% with the 8-m technique. Three blinded observers obtained a 100% sensitivity with both techniques and a specificity of 94-97% with the 1-m technique and 83-89% with the 8-m technique. CONCLUSION: The first minute of Gd-enhancement allows a more prominent differentiation between malignant and benign breast lesions than the following times.     

软组织肿瘤的MR灌注成像与MR波谱成像的比较研究

目的 通过分析软组织肿瘤同一病例相同感兴趣区的MR灌注加权成像(MR-PWI)及MR氢质子波谱(1H-MRS)的功能影像信息,比较两者用于软组织肿瘤的定性诊断价值.方法 研究同时行MR-PWI、1H-MRS的全身各部位软组织肿瘤共40例.比较MR-PWI及1H-MRS各参数在良、恶性肿瘤中的差异,进而对2种诊断方法进行评价.所获数据采用t检验或配对四格表确切概率法分析.结果 MR-PWI良、恶性软组织肿瘤的血流量(BF)值差异有统计学意义(t=2.531,P<0.05),血容量(BV)及平均通过时间(MTT)值差异均无统计学意义(t值分别为1.587和1.732,P值均>0.05);以BF值=4.35 ml·100 mg-1·min-1为阈值,MR-PWI诊断恶性肿瘤的敏感度为81.8%(18/22),特异度为72.2%(13/18).良、恶性软组织肿瘤的时间信号曲线(TIC)类型比较:Ⅰ a型在良性肿瘤中占3/18,在恶性肿瘤中占17/22;Ⅰ b型在良性肿瘤中占12/18,在恶性肿瘤中占3/22;Ⅰ c型在恶性肿瘤中占2/22.Ⅱ型在良性肿瘤中占3/18.良、恶性软组织肿瘤的胆碱(Cho)、肌酸复合物(Cr)、脂质(Lip)值差异均无统计学意义(t值分别为1.332、1.637、1.986,P值均>0.05),而Cho/Cr比值的差异有统计学意义(t=2.927,P<0.05);以Cho/Cr比值=3.22为阈值,1H-MRS诊断恶性肿瘤的敏感度为86.4%(19/22),特异度为88.9%(16/18).1H-MRS谱线比较:18例良性及17例恶性软组织肿瘤在2.0～2.1ppm(×10-6)处均未出现异常峰,而2例恶性神经鞘瘤和3例恶性纤维组织细胞瘤均在2.0～2.1ppm处出现异常峰.MR-DWI与1H-MRS用于恶性肿瘤诊断准确度的差异无统计学意义(X2=0.125,P>0.05).结论 软组织肿瘤的MR-PWI的BF值、1H-MRS的Cho/Cr比值有利于软组织肿瘤良、恶性的鉴别;软组织肿瘤的TIC形态有助于肿瘤良、恶性的鉴别.MR-PWI和1H-MRS两者用于诊断恶性软组织肿瘤的准确度无明显差异,1H-MRS诊断恶性软组织肿瘤的敏感度和特异度较高.     

Usefulness of diffusion-weighted MRI in differentiating benign from malignant musculoskeletal tumors

PURPOSE: To evaluate the usefulness of diffusion-weighted MRI in distinguishing different components and in differentiating benign from malignant musculoskeletal tumors. MATERIALS AND METHODS: Fifty-seven patients with musculoskeletal tumors underwent MR at our institution from October 1999 to April 2002. We evaluated 57 tumors (9 bone tumors and 48 soft tissue tumors). All tumors were classified into 8 groups (myxomatous, fibrous, cystic, cartilaginous, fatty components, hematomas, other benign tumors, and other malignant tumors). MR examinations were performed with a 1.5-Tesla system. Diffusion-weighted single-shot EPI images were obtained in all patients. Apparent diffusion coefficients (ADCs) were calculated by using b factors of 0 and 1,000 sec/mm2. RESULTS: ADC values of myxomatous, cystic, and cartilaginous components were significantly higher than those of other tumors. In cartilaginous tumors, malignant tumor ADC values (2.33 +/- 0.44) were higher than those of benign tumors (2.13 +/- 0.13). However, there was no significant difference between benign and malignant tumors. Except for high-intensity components on T1-weighted imaging and low or homogeneously very high intensity components on T2-weighted imaging, there was a significant difference in ADC between malignant (1.35 +/- 0.40) and benign (1.97 +/- 0.50) tumors. CONCLUSION: Within the limited number of cases, there was a significant difference in ADC between malignant and benign tumors.     

Breast lesions: evaluation with dynamic contrast-enhanced T1-weighted MR imaging and with T2*-weighted first-pass perfusion MR imaging

PURPOSE: To evaluate the diagnostic value of an imaging protocol that combines dynamic contrast-enhanced T1-weighted magnetic resonance (MR) imaging and T2*-weighted first-pass perfusion imaging in patients with breast tumors and to determine if T2*-weighted imaging can provide additional diagnostic information to that obtained with T1-weighted imaging. MATERIALS AND METHODS: One hundred thirty patients with breast tumors underwent MR imaging with dynamic contrast-enhanced T1-weighted imaging of the entire breast, which was followed immediately with single-section, T2*-weighted imaging of the tumor. RESULTS: With T2*-weighted perfusion imaging, 57 of 72 carcinomas but only four of 58 benign lesions had a signal intensity loss of 20% or more during the first pass, for a sensitivity of 79% and a specificity of 93%. With dynamic contrast-enhanced T1-weighted imaging, 64 carcinomas and 19 benign lesions showed a signal intensity increase of 90% or more in the first image obtained after the administration of contrast material, for a sensitivity of 89% and a specificity of 67%. CONCLUSION: T2*-weighted first-pass perfusion imaging can help differentiate between benign and malignant breast lesions with a high 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.     

多层螺旋CT对胃肠道外间质瘤的诊断价值

目的 探讨胃肠道外间质瘤(EGIST)的CT表现及其诊断价值. 方法 回顾性分析经手术病理证实的19例EGIST的CT资料.结果 肿瘤位于腹膜后8例、肠系膜4例,腹腔4例,原发于肾上腺1例、大网膜1例,网膜及肠系膜1例.良性2例,交界性4例,恶性13例.肿瘤直径4.1～35 cm,类圆形5例,分叶状5例,不规则形9例.平扫密度均匀4例, 增强扫描1例均匀中度强化,1例不均匀强化,2例周边明显环形强化;平扫密度不均匀15例,增强扫描实质部分中度以上强化,囊变坏死部分强化不明显. 结论 EGIST的CT表现具有一定特点, MSCT对EGIST的诊断及鉴别诊断有重要价值.     

Apparent diffusion coefficient mapping of salivary gland tumors: prediction of the benignancy and malignancy

BACKGROUND AND PURPOSE: Preoperative prediction of tumor malignancy is clinically very important, because this information strongly influences the surgical plan. We evaluate the preoperative apparent diffusion coefficient (ADC) maps of benign and malignant salivary gland tumors. MATERIALS AND METHODS: High-resolution MR imaging was performed on 31 patients with benign or malignant salivary gland tumors; ADC maps of the tumors were also obtained. Surface coils of 47 or 110 mm diameter were used to improve the image resolution. The ADCs were compared with histologic features of the excised tumors. RESULTS: The ADC maps effectively depicted the histologic features of the salivary gland tumors, such as presence of cancer cells, myxomatous tissues, fibrosis, necrosis, cyst formation, and lymphoid tissues. The ADC maps showed that more frequent areas with high ADCs (> or = 1.8 x 10(-3) mm(2)/s) were significantly greater in benign tumors than in malignant tumors. The sensitivity and specificity for high ADC occupying fewer than 5% of the area of a tumor was 89% and 100%, respectively, resulting in 97% accuracy, 100% positive predictive value, and 96% negative predictive value. CONCLUSION: The ADC may provide preoperative tissue characterization of the salivary gland tumors.     

Soft-tissue tumors: value of static and dynamic gadopentetate dimeglumine-enhanced MR imaging in prediction of malignancy

PURPOSE: To prospectively evaluate static and dynamic gadopentetate dimeglumine-enhanced magnetic resonance (MR) imaging relative to nonenhanced MR imaging in differentiation of benign from malignant soft-tissue lesions and to evaluate which MR imaging parameters are most predictive of malignancy, with associated interobserver variability. MATERIALS AND METHODS: One hundred forty consecutive patients (78 male patients [median age, 51 years], 62 female patients [median age, 53 years]) with a soft-tissue mass underwent nonenhanced static and dynamic contrast material-enhanced MR imaging. Diagnosis was based on histologic findings in surgical specimens (86 of 140), findings at core-needle biopsy (43 of 140), or results of all imaging procedures with clinical follow-up (11 of 140). Multivariate logistic regression analysis was used to identify the best combination of MR imaging parameters that might be predictive of malignancy. Subjective overall performance of two observers was evaluated with receiver operating characteristic analysis. RESULTS: For subjective overall diagnosis, area under the receiver operating characteristic curve, a measure for diagnostic accuracy, was significantly larger for combined nonenhanced and contrast-enhanced MR imaging than it was for nonenhanced MR imaging alone, with no significant difference between observers. Multivariate analysis of all lesions revealed that combined nonenhanced static and dynamic contrast-enhanced MR imaging parameters were significantly superior to nonenhanced MR imaging parameters alone and to nonenhanced MR imaging parameters combined with static contrast-enhanced MR imaging parameters in prediction of malignancy. The most discriminating parameters were presence of liquefaction, start of dynamic enhancement (time interval between start of arterial and tumor enhancement), and lesion size (diameter). Results for extremity lesions were the same, with one exception: With dynamic contrast-enhanced MR imaging parameters, diagnostic performance of one observer did not improve. CONCLUSION: Static and dynamic contrast-enhanced MR imaging, when added to nonenhanced MR imaging, improved differentiation between benign and malignant soft-tissue lesions.