Tumor recurrence versus fibrosis in the female pelvis: differentiation with MR imaging at 1.5 T

Twenty-two women with previous malignancies of the pelvis were examined with magnetic resonance (MR) imaging. In 21 of 22 patients, the MR imaging findings were confirmed with laparotomy on transvaginal biopsy. Twelve of the 22 patients had recurrent tumors; ten had a localized fibrotic mass, and two were found to have coexistent local fibrotic masses and distant recurrence. In 11 of the 12 patients with recurrence, MR imaging demonstrated the recurrent tumor as an area of increased signal intensity on long repetition time, long echo time spin-echo pulse sequences. Signal intensity of localized fibrosis varied with the time since initial treatment. Separate signal intensity measurements for T1- and T2-weighted images were obtained in regions of interest in recurrent tumors, early fibrosis (1-6 months after first treatment), and late fibrosis (more than 12 months). Ratios of signal intensity of muscle to that of fat were calculated, and a statistical analysis (Student t test) was performed. On heavily T2-weighted pulse sequences, the differences in signal intensity between late fibrosis and recurrent tumors were statistically significant (P less than .001). MR imaging is useful in identifying recurrent pelvic neoplasm and distinguishing it from posttreatment fibrosis.     

Incorporation versus infection of retroperitoneal aortic grafts: MR imaging features

The magnetic resonance (MR) imaging characteristics of normal aortic graft healing were compared with those of perigraft infection in 57 patients after aortic graft implantation. Thirty-three patients without postoperative complications underwent MR imaging in a 0.35-T unit 1 week after graft implantation, and 13 of those patients were reexamined 2-3 months after graft implantation. Twenty-four patients with clinically suspected perigraft infection underwent MR imaging 6 weeks to 18 years after graft implantation. Early normal postoperative changes were characterized by a perigraft collar of low to medium signal intensity on T1-weighted images and of high intensity on T2-weighted images in all 33 cases, consistent with perigraft fluid collection. In 10 of 13 patients reexamined 2-3 months postoperatively, the MR images demonstrated a collar of tissue consistent with perigraft fibrosis. In cases of clinical suspicion of retroperitoneal graft infection, MR imaging showed eccentric fluid collections of low to medium signal intensity on T1-weighted images and high intensity on T2-weighted images at more than 3 months after surgery. The MR findings were diagnostic of retroperitoneal perigraft infection in 17 of 20 patients shown to be infected at surgery. Retroperitoneal infection was correctly excluded on the basis of MR findings in four patients. Thus, MR imaging is an accurate imaging method for the diagnosis of aortic graft infection. In the early postoperative phase, resolving perigraft fluid cannot be differentiated from perigraft infection.     

CT and MR imaging in the evaluation of retroperitoneal fibrosis

We have performed CT and MR on five patients with biopsy proven retroperitoneal fibrosis (RPF). Magnetic resonance (MR) accurately displayed a retroperitoneal mass of low signal intensity on T1-weighted scans and of heterogeneous medium signal intensity on T2-weighted scans. The coronal MR views demonstrated a retroperitoneal mass: the shape, signal intensity, and effects on the ureters and major vessels appear characteristic of RPF.     

磁共振成像技术在腹膜后纤维化诊断中的价值

目的通过分析腹膜后纤维化（RPF）的MRI表现特点,提高其早期诊断水平。方法回顾性分析经临床病理证实的7例特发性RPF患者的MRI特点。结果腹膜后纤维化MRI表现为腹膜后不规则形的软组织信号肿块影,包绕腹主动脉,常累及下腔静脉及一侧或两侧输尿管;T1WI呈较低信号,T2WI信号强度不等。结论 MRI可清晰显示RPF的范围和并发症,有助于临床诊断。     

Mucinous versus nonmucinous rectal carcinomas: differentiation with MR imaging.

PURPOSE: To determine if quantitative and qualitative magnetic resonance (MR) imaging measures can help differentiation of mucinous from nonmucinous rectal tumors. MATERIALS AND METHODS: In 26 patients with pathologically proved mucinous (n = 9) and nonmucinous (n = 17) rectal tumors, MR imaging was performed with T1-weighted spin-echo (SE) and T2-weighted fast SE sequences in all patients and with a gadolinium-enhanced T1-weighted sequence in 18. With use of the signal intensity (SI) measurements in the tumors and reference tissues, tumor-to-muscle, tumor-to-fat, and tumor-to-urine SI ratios were calculated. In addition, the SI and contrast-enhancement patterns in the tumors were assessed qualitatively by three blinded readers. RESULTS: Mucinous tumors had a much higher SI on the T2-weighted fast SE images. Tumor-to-muscle, tumor-to-fat, and tumor-to-urine SI ratios were significantly higher in the mucinous compared with the nonmucinous tumors (P = .0004, P = .0008, and P = .00002, respectively). Qualitative evaluation of the SI correlated well between readers 1 and 2 (r = 0.93), readers 1 and 3 (r = 0.94), and readers 2 and 3 (r = 0.91). Agreement for the contrast-enhancement patterns was 67%, 72%, and 67%, respectively, with most mucinous tumors having predominantly high SI and a peripheral contrast-enhancement pattern. CONCLUSION: Mucinous and nonmucinous rectal tumors can be differentiated with MR imaging because mucinous tumors show high SI on T2-weighted fast SE images.     

Radiation fibrosis: differentiation from recurrent tumor by MR imaging

Magnetic resonance (MR) images of 21 patients who had undergone radiation therapy were analyzed and compared with those of 15 patients who had untreated tumors. T2-weighted images (TR = 1,500 msec, TE = 90 msec) were most helpful in distinguishing recurrent tumor from radiation fibrosis. Radiation fibrosis, like muscle, usually remained low in signal intensity on T2-weighted images, while tumor demonstrated higher signal intensity. In no patient was the signal intensity of tumor the same or less than muscle on the T2-weighted images. However, relatively high signal intensity on T2-weighted images is not specific for tumor recurrence and may be seen in acute radiation pneumonitis, infection, hemorrhage, and even pulmonary radiation fibrosis.     

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 imaging of recurrent colorectal carcinoma versus fibrosis

Locally recurrent cancer can be difficult to distinguish from postoperative and radiation fibrosis on most imaging modalities. We report a case in which magnetic resonance imaging suggested the presence of both fibrosis and recurrent tumor in a patient following abdominoperineal resection for colorectal carcinoma, and demonstrate its role for precise needle placement when percutaneous biopsy is recommended.     

MR扩散加权成像定量分析对纵隔良恶性病变的鉴别诊断

目的探讨MR扩散加权成像对纵隔良恶性病变的鉴别诊断价值。材料与方法对53例纵隔病变进行传统的T1WI和T2WI,并在b=0和b=1000s/mm2下行扩散加权成像,计算其表观扩散系数ADC值。用t检验对这两组ADC值     

Primary retroperitoneal angiosarcoma: MR imaging features

We report a rare case of retroperitoneal angiosarcoma in a 72-year-old man who presented with abdominal pain. Diagnosis was obtained histologically after radical excision of the tumour. Fat-suppression MRI after intravenous administration of the contrast agent gadolinium-DTPA was able to define tissue planes between the lesion and the adjacent structures, suggesting the vascular nature of the lesion, and provided useful information for an accurate surgical approach. To the best of our knowledge, this is the first report that illustrates the MRI characteristics of a retroperitoneal angiosarcoma. Received: 13 March 2000 Revised: 14 July 2000 Accepted: 17 July 2000     

MR imaging of retroperitoneal teratoma: correlation with CT and pathology

A retroperitoneal teratoma was studied with CT and magnetic resonance (MR) imaging. The images were correlated with the pathologic findings. The tumor was composed of five portions: adipose tissue, bone, hair, sebum, and loose edematous fibrofatty tissue with skin. Computed tomography and MR both demonstrated a well defined mass with separate cystic and solid components and all five tissue elements of the tumor. Magnetic resonance was superior to CT in delineating the relationship of blood vessels to the tumor.     

腹膜后纤维化的影像学诊断

目的:探讨腹膜后纤维化(retroperitoneal fibrosis,RPF)的影像学表现及诊断价值。方法:回顾分析了1996年11月~2006年2月收治的15例腹膜后纤维化患者的X线、B超、CT及MRI表现。结果:RPF的影像学表现为腹膜后弥漫性斑块或肿块及腹膜后脏器的浸润,多伴有肾盂输尿管扩张积水。结论:CT和MRI在腹膜后纤维化的诊断中起重要作用,并能进行分期及疗效监测。X线和B超对RPF的诊断起辅助作用,综合分析X线、B超、CT、MRI影像学表现有助于RPF的诊断。     

Small hepatocellular carcinoma versus small cavernous hemangioma: differentiation with MR imaging at 2.0 T

Eighteen small hepatocellular carcinomas (HCCs) and 38 hemangiomas less than 5 cm in diameter were studied with magnetic resonance (MR) imaging at 2.0 T. Relatively T1-weighted spin-echo (SE) 500/30 (repetition time msec/echo time msec) images and proton-density 2,000/30 images showed nonspecific contrast-to-noise ratios (C/Ns) and intensity ratios in HCCs and hemangiomas. On T2-weighted 2,000/60, 90, 120, 150, and 180 images, hemangiomas had significantly greater C/N and intensity ratios than HCCs (P less than .05). The SE 2,000/180 sequence showed the greatest difference in tumor-liver intensity ratios between small HCCs and hemangiomas, followed by the SE 2,000/150 sequence, but there was no statistically significant difference between the two pulse sequences. However, the SE 2,000/180 sequence is limited in the number of sections obtainable for routine clinical liver imaging. The findings indicate that the SE 2,000/60 sequence is optimal for the detection of small HCCs and hemangiomas and that the SE 2,000/150 sequence is optimal for distinguishing small HCCs from hemangiomas at 2.0 T.     

特发性腹膜后纤维化的MSCT表现

目的:探讨特发性腹膜后纤维化(IRPF)的CT表现特点,提高对该病的早期诊断准确性.方法:回顾性分析经病理证实的24例IRPF患者的病例资料,主要观察分析病变的部位、形态、范围、边界、密度、强化方式及邻近器官组织的受累情况.结果:本组患者的主要CT表现为肾门水平以下腹膜后区不规则形软组织密度影,近似肌肉密度,增强扫描病灶可无强化或明显强化;包绕腹主动脉前方和/或两侧18例,向下累及两侧髂总动脉8例,累及下腔静脉前方4例,累及肾动脉1例,受累血管均无明显移位;累及输尿管致梗阻性肾积水18例,其中8例双侧受累.结论:IRPF的MSCT表现具有一定特征性,可为临床诊治提供可靠依据.     

Patients with pulmonary fibrosis: cardiac function assessed with MR imaging

PURPOSE: To detect abnormalities in cardiac function by using magnetic resonance (MR) imaging in patients with mild to moderate pulmonary fibrosis and to evaluate the relationship between pulmonary function and cardiac function. MATERIALS AND METHODS: Sixteen patients were compared with 16 sex- and age-matched healthy control subjects. Systolic function was assessed by using multisection multiphase cine MR imaging. Diastolic function was assessed with flow-sensitive MR imaging across the mitral and tricuspid valves. MR imaging results were compared with the severity of impairment in pulmonary function. RESULTS: Biventricular systolic function and left ventricular diastolic function were normal in patients, but right ventricular diastolic function was significantly impaired versus that of control subjects, with a ratio of peak flow during early diastolic (E) filling to peak flow during atrial contraction (A) of 0.85 +/- 0.40 versus 1.28 +/- 0.50 (P =.035). Biventricular E/A ratios were strongly correlated to age in patients and control subjects. The right ventricular E/A ratio in patients corresponded with values that are normally expected in people 20 years older. Diastolic left and right ventricular functions were significantly correlated with each other. There was no relationship between pulmonary function and cardiac function. CONCLUSION: Impairment of right ventricular diastolic function was found by using MR imaging in patients with mild to moderate pulmonary fibrosis, whereas left ventricular diastolic function and biventricular systolic function were preserved.