Study Of Mr Imaging Of Mediastinal Tumors And Tumor-like Lesions

PARTⅠThe diagnosis of mediastinal tumors and tumor-like lesions on 3.0T MRIObjectives To analyze and summarize the performance of 3.0TMRI for mediastinal tumors and tumor-like lesions.To evaluate the role of 3.0T MRI in diagnosing mediastinal tumors and tumor-like lesions.Materials and Methods Forty patients with mediastinal tumors and tumor-like lesions underwent 3.0TMRI. Of mediastinal tumors and tumor-like lesions, 22 were originated from the thymus, includede 10 cases of benign tumor and 12 cases malignant tumor, 10 were originated from nerve, included 6 cases of neurilemmoma, 4 cases of neurofibroma, 2 cases thymic cyst, 2 cases of bronchial cyst, 1 case of esophageal cyst, 1 case of teratoma, 1 case of leiomyoma of esophagus, 1 case of nodular goiter. All cases were examined with 3.0T magnetic resonance machine. 8-channel TORSOPA coil was used. ECG-gated technique and Respiratory-gated and Respiratory Compensation technique were used. Three-planar (axil, sagittal, coronal) scans and enhanced MRI (axil, coronal) were performed. MRI scanning use SE and SPGR sequences. To analyze the performance of 3.0TMRI for the mediastinal tumors and tumor-like lesions and the imaging signs including the tumor site, shape, changes around the tumor, the intratumor structure and relationship with tissue and organ on MRI.Results Combined the results of pathology and clinical, all cases were located accuratly, 37 cases were diagnosed accuratly before surgery, internal components of 38 cases of mediastinal mass were determined. 40 cases of mediastinal mass in the performance of 3.0TMRI: (1) Of 26 cases of anterior mdiastinal tumors and tumor-like lesions, 10 cases of benign thymoma, 12 cases of malignant thymoma, 2 cases of thymic cyst, 1 case of teratoma, 1 case of nodular goiter. Benign thymoma was round or oval , its edge was clear and smooth, the signal intensity was homogeneous, it showed intermediate signal in T1-weighted images, it showed slightly higher signal in T2-weighted images, it showed uniform signal in hanced images. Malignant thymoma was irregular, its edge was protuberant liked nodules and cusp, the signal intensity was unhomogeneous, it showed irregular signal in hanced images, the normal fat sinal disappeared around it. 2 case of thymic cyst were like round, 1 case of hymic cyst showed low signal on T1WI, and the other case showed hign singnal on T1WI, they both showed very high signal on T2WI, the edge of cyst signal was enhanced and the intracapsular components weren't enhanced in hanced images. 1 case of cystic teratoma showed multiple cystic signal on the T1WI and T2WI, there were high signal of fat and no signal of calcification, it showed non-uniform reinforcement in hanced images. 1 case of nodular goiter showed unhomogeneous signal intensity, it showed non-uniform reinforcement in hanced images, it connected to the left thyroid gland upward and conncected to the middle mediastinum down.(2) 2 cases of middle mdiastinal tumors and tumor-like lesions were all bronchogenic cysts, the signal intensity was more homogeneous, and there was liquid-liquid plane in the T1WI and T2WI images of 1 case of bronchogenic cyst, bronchogenic cysts were no enhancement and had a relationship with the neighboring bronchial closer. (3) Of 12 cases of posterior mdiastinal tumors and tumor-like lesions, 10 cases of neurogenic tumor, included 6 cases of neurilemmoma, 4 cases of neurofibroma, 1 case of esophageal cyst, 1 case of leiomyoma of esophagus. 6 cases of neurilemmoma were oval-shaped, they were larger and easy to cystic change,necrosis and hemorrhage than neurofibroma of it. 4 cases of neurofibroma showed slightly lower signal in T1WI, and showed heterogeneous high signal in T2WI, it showed non-uniform reinforcement in hanced images, one of which expand foraminal. 4 cases of neurofibroma were oval-shaped, they showed intermediate signal in T1WI and showed heterogeneous high signal in T2WI, it showed lower reinforcement in hanced images, two of which expand foraminal. 1 case of esophageal cyst showed homogeneous signal intensity and low signal in T1WI and showed high signal in T2WI, esophageal cyst was no enhancement and had a relationship with the esophageal. 1 leiomyoma of esophagus showed homogeneous signal intensity and slightly lower signal in T1WI and showed slightly higher signal in T2WI and it was no enhancement and had a relationship with the esophageal. 1 case of nodular goiterConclusion The basic signs of the mediastinal tumors and tumor-like lesions could be demonstrated well on 3.0 TMRI and especially the important value of the detection performance of the relationg of the tumor and tumor-like lesion with structure and organ and analyzing component of the tumor and tumor-like lesion. 3.0TMRI imaging can be a important imaging technique for the mediastinal tumors and tumor-like lesions..PARTⅡApplication in evaluation of diffusion-weighted MR imaging in mediastinal tumorsObjective To analyze the appearance of different mediastinal tumors on diffusion- weighted imaging, and to evaluate the value of this technology to the diagnosis and difference of mediastinal tumors.Methods Diffusion-weighted MR imaging (b value is chosed 500s/mm2and 800s/mm2) and measurement of apparent diffusion coefficient (ADC) were performed in 32 patients and the feature of mediastinal tumor were observed. Of mediastinal tumors, 22were originated from the thymus, includede 10 cases of benign tumor and 12 cases malignant tumor, 10 were originated from nerve, included 6 cases of neurilemmoma, 4 cases of neurofibroma. The ADC values were obtained and compared between malignant and benign of thymoma, neurilemmoma and neurofibroma. And the rsultant data were analyzed and independent samples t-test were performed with software SPSS 11.5.Results (1) Ten cases of benign thymoma showed hypointense signal on DWI and hyperintense signal on corresponding ADC maps, their signal intensity was inhomogeneous. Twelve cases of malignant thymoma showed hyperintense signal on DWI and hypointense signal on corresponding ADC maps, their signal intensity were inhomogeneous. Six cases of neurilemmoma showed slightly hypointense signal on DWI and slightly hyperintense signal on corresponding ADC maps, their signal intensity was inhomogeneous obviously. Four cases of neurofibroma showed slightly hyperintense signal on DWI and slightly hypointense signal on corresponding ADC maps, their signal intensity was inhomogeneous. (2) The ADC value of benign thymoma, malignant thymoma, neurilemmoma and neurofibroma were higher when b value was 500 s/mm2 than them when b value was 800s/mm2(P﹤0.05). There was significant difference beween ADC of benign and malignant of thymoma, neurilemmoma and neurofibroma when b value was 500, 800s/mm2(P﹤0.05).Conclusion Comparied with MR T1WI and T2WI, the internal structure of tumors could be displayed clearly in the DWI map and ADC map while the ADC values could reflect the different nature of the tumor with the change of state of water molecules. Combind DWI map and ADC map with ADC valuesm, diffusion-weighted MR imaging is valuable for the diagnosis and differentiated diagnosis of benign and malignant thymoma, and it is also valuable for the diagnosis and differentiated diagnosis of neurilemmoma and neurofibroma. So it is a useful supplement for conventional MRI. PARTⅢApplication in evaluation of perfusion-weighted MR imaging in mediastinal tumorsObjective To analyze the appearance of mediastinal tumors on diffusion-weighted imaging, and to evaluate the value of this technology to the diagnosis and difference of mediastinal tumors.Methods 32 patients with mediastinal tumors underwent perfusion-weighted MR imaging with 3.0TMRI machine. Of mediastinal tumors, 22were originated from the thymus, includede 10 cases of benign tumor and 12 cases malignant tumor, 10 were originated from nerve, included 6 cases of neurilemmoma, 4 cases of neurofibroma. T1WI perfusion-weigthed MRI finding in 22 patients of thymoma. T2*WI perfusion-weigthed MRI finding in 10 patients of neurogenic tumors. The SI-T was analyzed and the TTM, MSD, TTPand MSI were calculated with functool 2. To compare benign thymoma and malignant thymoma, then compare neurilemmoma and neurofibroma, and to analyze these the difference of perfusion value. The rsultant data were analyzed and Wilcoxon rank sum test were performed with software SPSS 11.5.Results (1) The SI-T curves of benign thymoma showed,while malignant thymoma showed TTM of benign thymoma was 15.903±3.577, while TTM of malignant thymoma was 18.668±10.900, and then MSD of benign thymoma was161.220±61.805, while MSD of malignant thymoma was 450.393±131.605, and MSI of benign thymoma was 451.577±136.498. The difference of TTM, MSD and MSI between benign and malignant thymoma was statistically significant (P﹤0.05). TTP of neurilemmoma was 408.053±9.893, while TTP of neurofibroma was 405.400±16.633, and then MSI of neurilemmoma was 7.657±1.577, while MSI of neurofibroma was 8.147±1.830. The difference of TTP and MSI between neurilemmoma and neurofibroma was no statistically significant(P﹥0.05). Conclusion Perfusion-weighted MR imaging (PWI) is valuable for the diagnosis and differentiated diagnosis of benign thymoma and malignant thymoma, while it is little valuable for the differentiated diagnosis of neurilemmoma and neurofibroma. So it is supplement for conventional MRI.