Application Of CT Quantitative Analysis In Diagnosis And Treatment Of Malignant Pleural Mesothelioma

Objectives Malignant pleural mesothelioma is a rare invasive tumor developed by pleural mesothelial cells.The prognosis is poor,and the natural survival time in most patients is less than a year.The early clinical manifestations of MMP are atypical and are similar to those of benign pleural diseases,thus,the misdiagnosisand is easily occured.However,when the disease progresses to a certain extent and a definitive diagnosis is reached,the best treatment opportunity has been lost.Conventional imaging diagnosis relies largely on the ability of the radiologist to identify the scanned images,and the uniform standards for diagnose are lack.Quantitative analysis can minimize the subjective impact of doctors.One of the aims of this study is to establish a CT quantitative analysis standard for malignant pleural mesothelioma.The other aim is to evaluate the effect of chemotherapy or surgery for treating MPM using CT quantitative analysis.Methods 1.CT analysis in differential diagnosis between malignant pleural mesothelioma and tuberculous empyema:The imaging and clinical data from 26patients with MPM and 30 patients with tuberculous empyema in our hospital in recent5 years were analyzed retrospectively.The possible typical CT feature of MPM was searched through literature analysis.The imaging characteristics were compared between these two groups,and the sensitivity of each index in diagnosing of MPM was calculated.2.Tumor area measurement for response assessment in malignant pleural mesothelioma:The baseline scan and the follow-up scan were collected from15 patients with MPM.Three observers contoured tumor on three selected CT sections from each scam.The tumor was extracted and calculated using Photoshop software package.The interobsever variability was analysed using a random effects analysis of variance model.The correlation between the area measurements and the modified RECIST standard was assessed using SPSS.3.Computer aided volumetric assessment for response assessment in malignant pleural mesothelioma:Forty-five CT scans were collected from 15 cases.A computer-aided random walk-based algorithm was applied to segment the tumour by 3 observers.The results were then compared to radiologist-drawn contours and correlated with measurements made uing modified RECIST standard.4.Quantitative measurement of lung re-expansion in patients with MPM undergoing pleurectomy/decortication:A databse of 12 patients demonstrating unilateral MPM was collected.Each patient underwent a pre-surgical CT scan,surgical debulking by P/D,and two post-surgical CT scans(at one and four months).The lung volume was measured in each scan using an automated algorithm and compared for each patient across time.Results 1.CT analysis in differential diagnosis between malignant pleural mesothelioma and tuberculous empyema:There was no significant difference on the severity of pleural effusion,the involvement of lung and chest wall between the two groups.MPM patients were apt to lead to irregular pleural thickening and lymph node metastasis,while tuberculous empyema patients were more likely to show regular pleural thickening and thoracic volume shrinking.The sensitivity and specificity of the single diagnosis index were poor.The scores were calculated through all the indexs,and the area under the curve of ROC was 0.990,and the cut-off value was 0.5.The sensitivity of the total scores for diagnosing MPM was 100%,and the specificity was90%.2.Tumor area measurement for response assessment in malignant pleural mesothelioma:The mean per-section area in baseline scan was 25.62 cm~2,while the summed area was 76.86 cm~2.In the follow-up scan,the mean per-section and summed area was 24.52 cm~2 and 73.55 cm~2 respectively.The interobserver variability is relative high.The change in tumor area during treatment was similar to that of the modified RECIST standard score.3.Computer aided volumetric assessment for response assessment in malignant pleural mesothelioma:A high accuracy was achieved between the random walk method and manual method.The mean time for three-dimensional reconstruction and volume calculation was 23.1 min.The interobserver variability is relative small.A linear correlation was established between the changed in computed tumour volume and modified RECIST.4.Quantitative measurement of lung re-expansion in patients with MPM undergoing pleurectomy/decortication:The average of all the patients before the ipsilateral lung volume was(1259.76+865.07)cm~3.The median ipsilateral volume increase was 44%relative to the pre-surgical ipsilateral volume and 21%relative to the contralateral volume.A statistically significant change in ipsilateral lung volume was not observed between 1-month and 4-month post-surgical scans.Conclusion 1.CT is helpful in differential diagnosis of MPM and tuberculous empyema,on the basis of the patients’medical history,the pleural thickening,the lymph node metastasis and the changes of thoracic volume.2.Despite the ability of tumor area measurements to capture tumor burden with greater than linear tumor thickness measurements,manual area measurements may not be a robust means of response assessment in mesothelioma patients.3.The computer aided volume assessment method based on random walk is faster,have less interobserver variability,and can evaluate the treatment efficacy.4.Debulking of MPM with P/D substantially increased the ipsilateral lung volume relative to both the pre-surgical,ipsilateral volume and the contralateral lung volume.This improvement persisted months after surgery.