Differential Diagnosis Of MR Diffusion Weighted Imaging In Lung Neoplasm And Compare With Pathology

Objective To investigate differential diagnosis of MR diffusion weighted imaging in lung neoplasm and ADC values in the characterization of the lung neoplasm, and analyze features of signal intensity and ADC values compared with different histopathologic types.Methods 82 patients(65 men,17 women, age range 22～80, mean age,58.1) with pulmonary masses at chest computed tomography from March 2010 to March 2011 were confirmed by pathology and clinical follow-up.There were 61 patients with 62 malignant masses, including 31 patients with central lung masses,29 patients with peripheral lung masses,1 patient with metastatic tumor; there were 21 patients with 22 benign masses. All patients were underwent routine MRI and DWI with SE-EPI combination in respiratory trigger technique after CT examination, by using different b values (Os/mm2,600s/mm2,800s/mm2 and 1000s/mm2). All post processing were performed in the ADW 4.4 workstation. The signal intensity of thoracic cord was considered as the reference, signal intensity of masses were recorded on all DWI images with 4 rank scale without knowledge of clinical data and pathology. This scale was as follows:low signal intensity,slight low signal intensity,isointensity and higher signal intensity (low signal intensity≤that of muscle, slight low signal intensity between in that of the muscle and the thoracic spinal cord, isointensity almost equal to that of the thoracic spinal cord, and higher signal intensity> that of the thoracic spinal cord) and ADC value in each mass was calculated. To compare mean ADC values among groups,analysis of variance was used. Independent-samples T test was used in two independent sample mean ADC values. The receiver operating characteristic (ROC) curve was used for evaluating diagnostic values of ADC with different b values in differentiation malignant pulmonary tumors from solid benign tumors. In addition, evaluation DWI and ADC value of masses was in correlation with different histopathologic types. Statistical analyses were performed by using statistical software (SPSS version 16.0). A P value of less than 0.05 was considered to indicate a statistically significant difference.Results signal intensity of masses on DWI imaging:the majority of solid benign tumors were low or slight low signal intensity, but fungal granuloma and non-specificial granuloma were isointensity or heperintensity, the most malignant pulmonary tumors were isointensity or higher signal intensity on DWI. ADC values of pulmonary tumors in the different b values:ADC values of the benign tumors in different b values (600s/mm2800s/mm2and 1000s/mm2) were (2.194±0.639)x10-3mm2/s,(1.776±0.637)x10-3mm2/s and (1.507±0.385)x10-3mm2/s respectively, ADC value of the malignant pulmonary tumors were (1.484±0.384)x10-3mm2/s,(1.294±0.342)x10-3mm2/s and (1.166±0.331)x10-3mm2/s respectively. By one-factor analysis of variance, ADC values of benign tumors and malignant pulmonary tumors with the different b values was significantly difference(F=16.156, P<0.000; F=12.716, P<0.000). By independent-Samples T test, ADC values of the benign and malignant tumors was significantly difference(t=6.179, P<0.000; t=4.442, p<0.000; t=3.980. p<0.000). By ROC curve analysis, the ADC values obtained from each b value were profit for differentiation between benign and malignant tumors. The areas under ROC curve(Az) in three b values were 0.827,0.743 and 0.790 respectively. The area under ROC curve with b value of 600s/mm2 was the largest. The optimal ADC threshold value of 1.693 X 10-3mm2/s yielded sensitivity 79%and specificity 82.6%. When b value as 600s/mm2, ADC values of squamous cell carcinomas,adenocarcinomas,adenosquamous carcinomas,large cell carcinomas,small cell carcinomas and metastatic tumor were (1.477±0.332)x 10-3mm2/s,(1.314±0.384)x10-3mm2/s, (1.315±0.118)×10-3mm2/s,3.013x10mm2/s,(1.514±0.176)x10-3mm2/s and 1.310x10-3mm2/s respectively. ADC value of large cell carcinomas was significantly highest in that of other malignant pulmonary tumors, ADC value of small cell carcinomas was significantly higher than that of squamous cell carcinomas,adenocarcinomas and adenocarcinomas, but lower than that of large cell carcinomas. ADC values of squamous cell carcinomas,adenocarcinomas and adenosquamous carcinomas were similar. The different differentiated squamous cell carcinomas and adenocarcinomas may be different ADC values, ADC values of high differentiated squamous cell carcinomas and adenocarcinomas were more higher than that of the low differentiated.,ADC values were decreased for poorly differentiated squamous cell carcinomas and adenocarcinomas. ADC values of tuberculous granuloma,non-specificial granuloma,fungal granuloma,lung abscess,hematolymphangioma with infection and non-change tumors with follow up in the benign tumors were (1.993±0.715)×10-3mm2/s,(1.775±0.771)×10-3mm2/s,(1.543±0.289)×10-3mm2/s,(1.885±0.568)×10-3mm2/s,1.87X 10-3mm2/s and(2.593+ 0.550)×10-3mm2/s, ADC value of fungal granulomas was significantly lower than that of other benign tumors, similar to that of small cell carcinomas.Conclusions DWI and ADC value are useful in the difference malignant pulmonary tumors from solid benign tumors,but diagnostic value of fungal granuloma in lung is small; in addition, ADC value may be helpful to indicate the different differentiated squamous cell carcinomas and adenocarcinonmas.