Diagnostic Value Of CT Perfusion And MR Diffusion-weighted Imaging In Adrenal Tumors And Correlation With Pathology: A Preliminary Study

Objective: The aim of the study was to explore the appearance of adrenal tumors on CT perfusion and evaluate the value of this technology for differentiation of adrenal tumors.Materials and Methods: With the same scanning parameters, thirty-eight patients with thirty-nine masses, including twenty-one adenomas, eighteen non-adenomas, were enrolled. The method of scanning included plain CT scan, CT perfusion imaging, and conventional enhanced CT scan. After plain CT scanning, CT perfusion was performed during a single breath-hold with Cine model. A single slice or four slices, with the maximum diameter of tumor was scanned repeatedly for 40s after 7s-9s intravenous bolus injection 40ml of nonionic contrast media at a rate of 4ml/s. As a result, 40 slices and 320 slices (40 slices x8) or 160 slices (40 slices x4) could be obtained from single detector or 16-detector spiral CT scanner respectively. Time-density curve (TDC) and four perfusion parameters virtual color imaging which reflecting perfusion status of tumors, named BF, BV, MTT and PS images were obtained. By mean of body perfusion software in perfusion III software packages, TDC and each of the perfusion parameters were calculated with the modified-deconvolution method. TDC configurations were analyzed and the discrepancies of CT perfusion parameters were compared. Then, ROC curve analysis was performed in order to determine the optimal threshold value for diagnosis and differentiation of adrenal tumors.Results: There are three types TDC: quickly rise and fall type, quickly rise and platform type, flat type, and the quickly rise and slowly rise type occupies the mostof them, adenoma occupied 54.5%, non-adenoma occupied 45.5% respectively. It is not helpful when TDC was regarded as diagnostic and differential standard for adrenal tumors;however, it is of importance for the perfusion parameters when they are were measured. There are difference about the blood flow perfusion status between adenoma and non-adenoma. The adenoma's perfusion is mainly homogeneous, sometimes, high perfusion could be seen in Cushing's adenomas;the non-adenoma's perfusion is usually inhomogeneous, high perfusion could be seen in the peripheral area of tumors and low perfusion could be seen in the center part of tumors, and it is obviously particularly in pheochromocytomas. For the CT perfusion parameters, there are remarkable differences between high and low perfusion area in non-adenomas, and the diagnostic value of the perfusion parameters is optimal if they were measured from the low perfusion area in non-adenomas. Accordingly to it, the mean value of BF, BV, MTT and PS of non-adenoma is (35.22±21.14) ml.min"1100g"1,(6.18±4.39)ml.l00g~1,(14.58±5.31)sand(15.26±11.35) ml.mhV'lOOg"1 respectively;The mean value of BF, BV and PS of adenoma is (112.1±48.15)ml.min"1100g"1,(14.01±6.05)ml.l00g"1and(26.50±16.47) ml.min^lOOg'1 respectively, much greater than non-adenomas, but MTT is (10.98±3.37)s and less than that of non-adenomas. There is significant statistic difference between perfusion parameters of adenomas and non-adenomas (p<0.05). The method measuring non-adenomas with low perfusion area is an optimal choice in order to diagnose and differentiate adenomas and non-adenomas. By means of ROC curve analysis, the sensitivity and specificity to diagnose adenomas is 95%, 61% and 100%, 67% and 67%, 67% when the threshold value of BF, BV and PS is chose at BF ^ 42.82ml.min"1100g'1, BV ^ 6.65ml. lOOg'1 and PS ^ 17.96 ml.min'' lOOg"1 respectively;the sensitivity and specificity to diagnose non-adenomas is 72% and 67% when the threshold value of MTT is chose at MTT^ 12.43 s. Conclusions: It is an optimal and practical method of CT perfusion that cine model was performed during a single breath-holding after 7s-9s of intravenous bolus injection of 40ml nonionic contrast media at a rate of 4ml/s. There are differential blood flow perfusion features in adrenal tumors. By means of perfusion virtual color functional imaging, namely, BF, BV, MTT and Ps imaging and quantitative analysis perfusion parameters, the hemodynamic and biological features of adrenal tumor could be demonstrated in vivo.Section IIThe Preliminary Study of Correlation between Angiogenesis and CTPerfusion of Adrenal Tumors7Objective: The aim of the study was to continue to accumulate cases and to evaluate angiogenesis of adrenal tumor further. Then, a correlation analysis was performed between angiogenesis and CT perfusion parameters of adrenal tumors so that we could evaluate the growth rule of adrenal tumor in vivo.Materials and Methods: Thirty-three patients with thirty-four masses were enrolled, including seventeen adenomas and seventeen non-adenomas. All masses were confirmed pathologically after surgical resection. The method of CT perfusion is the same with section I. According to the result from the section I , when measuring perfusion parameters, we chose the low perfusion area in non-adenomas. The immunohistochemical staining method and electron microscopy were applied to the angiogeneous analysis. After all the histological specimens was stained with CD34, VEGF, by use of a optical microscope, observing the tumor's micro-vascular modality and measuring the mean MVD, VEGF expression, in the mean time, the micro-vascular conformation were observed by use of an electron microscope. The dicrepencies of MVD and VEGF was compared between adenomas and non-adenomas;the relationship of MVD and VEGF and CT perfusion parameters were analyzed.Results: For CT perfusion parameters, there is significant statistic difference between adenomas and non-adenomas. The value of BF, BV and PS in adenoma is greater than that of non-adenomas;(p<0.05);the value of MTT in adenoma is longer than that of non-adenoma (p<0.05) as well. The mean MVD, VEGF expression of adenomas is higher than that of non-adenomas. There is significant statistic difference between each other (p<0.05). The BF and BV are positive correlated with MVD respectively (r=0.666,/?<0.01;r=0.496,/?<0.01). To compare with BF, the correlation extent is less between BV and MVD;but there is no correlation between PS and MVD(r=0.246> p=0.16).The BF is positive correlation with VEGF(p<0.05);MTT is negative correlation with MVD and VEGF(r=0.43k r=0.361, p<0.05), but the PS is not correlate with VEGF (p>0.05). The modal features of microvessel between adenomas and nonadenomas are ununiform. The ultra-structure of non-adenomas is similar to that of malignant tumor, there is remarked difference to that of adenomas. The variance in ultra-structure of adenoma and non-adenoma is a determinant factor for PS.Conclusions: The angiogenesis of adenomas is not similar to that of non-adenomas;and so is microvessel modality. The mean MVD, VEGF expression of adenomas is higher than non-adenoma. For the micro-vascular ultra-structure, adenomas are not in accordance with non-adenomas. It is verified that there is a correlation between MVD, VEGF expression, micro-vascular ultra-structure and CT perfusion parameters. By CT perfusion, the tumorous hemodynamic changes are not only quantified but also the vascularity could be predicted, as a consequence, evaluating tumorous angiogenesis may be possible in vivo.Section DI The Preliminary Study of MR Diffusion-Weighted Imaging ofAdrenal TumorsObjective: The aim of the study is to explore the appearance of adrenal tumors on diffusion-weighted imaging, and to evaluate the value of this technology to the diagnosis and difference of adrenal tumors.Materials and Methods: With the same scanning parameters, forty patients companied with forty-seven masses, including eighteen adenomas, twenty-nine non-adenomas were enrolled. With a single breath-hold, SE-EPI-DWI was performed in all patients, b value is chose 0, 1000 s / mm2, 0^ 800 s / mm2, 0, 500 s / mm2and 0, 300 s / mm2 respectively. The diffusion sensitive gradient was applied to X, Y, Z three directions at the same time. TR/4000ms, TE/64.6-50.9ms. The feature of adrenal tumors was observed. The difference of ADC was analyzed and compared between malignant and benign of adrenal tumor, adenoma and non-adenoma. In order to determined the optimal b value for DWI and the optimal ADC threshold value to diagnosis and difference for adrenal tumor, the ROC curve was analyzed. Results: On DWI, there are different features and ADC for adrenal tumor. The signal intensity of tumor is correlative with b value used and texture of tumor. Adenomas always show homogeneous intensity and non-adenoma show homogeneous or heterogeneous intensity, in particularly, the cystic and necrotic region shows lower inhomogeneous intensity such as metastasis and pheochromocytomas. When the b value was increased, the intensity of tumor is obviously attenuated, and the extent from the viable part of tumor is less than the cystic or necrotic part. For ADC, benign adrenal tumor is different from malignant (F=48.27, p=0.0001), and the ADC of benign tumor is greater than that of malignant;but there is no statistic difference between adenomas and non-adenomas(F=1.68, /?=0.2018). With the b value increased, the ADC of all the benign adrenal and malignant tumors, adenomas and non-adenomas were tend to dominate, and there were significant statistic difference when compared with each other (p<0.05) .By ROC curve, the threshold value of ADC obtained from each b value is valuable to diagnosis and difference of adrenal benign or malignant tumor, especially, when b chose 0^ 800 s/ mm2, the area of under ROC curve is the most largest, the sensitivity and specificity of diagnosis for adrenal benign tumor is 79 %, 72 % respectively at the ADC ^1.21x10'W/ s. Conclusions: By means of optimal b value, the microstructure of adrenal tumorcould be visually, directly, demonstrated in detail on diffusion-weighted imaging, in the mean time, recurring to the ADC that reflects the movement of water molecule within tumors, we could differentiate adrenal tumor through quantitative numerical value at the level of molecule, DWI is a helpful supplement for conventional MRI examination.Section IV The Preliminary Study of Correlation between Apparent DiffusionCoefficient and the Cellularity Density of Adrenal TumorsObjective: The aim of the study is amylase the correlation between apparent diffusion coefficient and the cellularity of adrenal tumors, and to explore the mechanism by which adrenal tumor has different apparent diffusion coefficient. Materials and Methods: Twenty-seven patients with twenty-eight masses were enrolled, including twenty-five benign and three malignant adrenal tumors. DWI is the same as section III.Histological specimens were stained with hemotoxylin and eosin, and slices were analyzed by mean of optical microscopy, tumor cellularity, by CMIAS(colored multifunction image analyzing system, the ratio was defined as the total area of tumor cells nuclei divided by the area of the histologic section (original magnification x 200), a mean value of five visual fields was regarded as the cellularity of each specimen expressed by percentage. The correlation of ADC and cellularity was analyzed.Results: When four different b values were used respectively, the negative correlation between ADC and cellularity is always determined. There is an optimal extent when b was equal to 0, 800 s / mm2 (r= -0.723, p=0.0l). This is in accordance with the result that the ADC is useful to the diagnosis and differentiation of adrenal tumor if b value was chose 0, 800 s / mm2 in section III.Conclusions: Tumor cellularity is one of the important factors that affected ADC of adrenal tumors. Measuring ADC, perhaps, is a new method would be found, which can differentiate and grade histopathology of adrenal tumors in vivo.