| 1.1 Objective To evaluate the diagnostic accuracy of nonenhanced single source dual energy spectral CT(ss DECT)in differentiating hyperdense adrenal adenomas and Pheochromocytomas.1.2 Materials and Methods This was a retrospective study conducted at Dalian medical university,China using the data collected from August 2011 to December 2016.Patients underwent abdominal CT scan in the hospital were enrolled which were later confirmed on histopathology with hyperdense mass having CT attenuation value ?20 HU on non-enhanced CT images in adrenal gland.Finally,the study comprised a total of thirty-six(n=36)patients.Seventeen(n=17)patients were adrenal adenomas and nineteen(n=19)were pheochromocytomas on histopathology.CT scanner and scan parameters should be mentioned here.The data were transferred onto GSI workstation to calculate the CT attenuation value(HU)for each lesion at different energies on monochromatic spectral images against 40 to 140 ke V and material decomposition including fat(water)and blood(water)material concentration were measured.All measured images had both 2.5 mm of slice thickness and spacing.The adrenal mass was detected and the images were carefully observed for excluding any calcification,haemorrhage or cystic change within the lesion and placing our region of interest(ROI)on the image slice showing largest diameter of adrenal lesion.Spectral Hounsfield(HU)curve was generated taking CT attenuation value(HU)as function of photon energies from 40 to 140 ke V and slope(k)of the spectral HU curve was calculated.From material decomposition images fat(water)material density and blood(water)material density were measured.Besides effective atomic number(z)was also measured for all the lesions.The consistency between the data of two observers was assessed through spearman rank correlation test.Independent sample Mann-Whitney U test was used to compare age,diameter,the CT values at the monochromatic images(40 to 140 ke V),the slope of spectral curve(k),fat(water)concentration,blood(water)concentration and effectiveZ number in both groups.The chi-square test was used in terms of sex and curve type(ascending/straight/descending).Receiver operating curve(ROC)analysis was preformed to find out the best cut-off values for all the parameters to obtain best diagnostic accuracy(sensivity and specificity).P value <0.05 was considered statistically significant during whole process of statistical analysis1.3 Results We did not find any statistically significant difference between age and gender among both groups.Pheochromocytomas exhibited larger median diameter than adenomas(4.16,2.56 cm.P <0.05).Inter-observer consistency for all the parameters was found to be excellent(r > 0.9,P <0.05).Using conventional CT(70 ke V)and for energies higher than 70 ke V no significant difference in median CT attenuation values was observed among both groups(±26.24,38.70 HU.P > 0.05).However,HAAs exhibited smaller median CT values than pheochromocytomas for lower energies(40.66,58.61 HU.40 ke V),(30.95,48.67 HU.50 ke V),(28.05,43.25 HU.60 ke V)(P < 0.05).The CT attenuation values showed maximum AUC of 0.805 for 40 ke V at a cut-off value of 43.65 and can discriminate hyperdense adenomas from pheochromocytomas with sensitivity of 84.2% and specificity of 70.6%.The entire spectral curves for pheochromocytomas appeared descending(100% n=19/19 vs 58.8% n=10/17 P<0.05).AUC of 0.706 was obtained for descending curve type with sensitivity of 100.0% and specificity of 41.2%.Median Slope Value was greater for hyperdense adenomas than for pheochromocytomas(-0.172,-0.290.P < 0.05).The slope values(k)showed maximum AUC of 0.786 at a cut-off value of-2.02 mg/ml with sensitivity of 58.8% and specificity of 94.7%.The median effective z number for pheochromocytomas was significantly greater(7.70,7.82.P < 0.05).A maximum AUC of 0.802 at a cut-off slope value of 7.76 was obtained with sensitivity of 68.4% and specificity of 82.4%.Median Fat(water)concentration values in hyperdense adenomas was greater(-170.55,-284.74 mg/ml.P < 0.05)with maximum AUC of 0.833 at a cut-off value of-198.06mg/ml(sensitivity 64.7%,specificity 94.7%).Median Blood(water)concentration values for pheochromocytomas was greater(719.11,1198.57mg/ml.P < 0.05).and showed maximum AUC of 0.833 at a cut-off value of 835.65 mg/ml(sensitivity 94.7%,specificity 64.7%).1.4 Conclusion In this study,CT value of 70 ke V can't differentiate two tumours.CT value of 40,50,60 ke V have statistic differences.Pheochromocytomas exhibited higher median CT values for lower energies.Other imaging parameters can also be used to discriminate between hyperdense adenomas from pheochromocytomas.Better sensitivity and specificity was obtained using 40 ke V energy.k and Fat(water)concentration had a better diagnosed specificity,and Blood(water)concentration gave us better diagnosed sensitivity... |
PDF Full Text Request