Value of CT Density Measurements in Distinguishing Parathyroid Adenoma,Thyroid,and Lymph Node.

Objective To explore the value of multi-phase contrast-enhanced computed tomography in the differential diagnosis of parathyroid adenoma,lymph node,and thyroid. Methods The enhanced multi-slice CT (MSCT) results of 21 parathyroid adenoma patients were analyzed,and their postoperative pathological specimens were examined. During the MSCT,the plain CT scan was recorded,along with the density of thyroid adenoma,lymph nodes,and thyroid at 35 s and 65 s (D0,D35,D65) following the injection of contrast medium. Results During the D0 phase,there was significant difference in CT values between the parathyroid adenoma and thyroid parenchyma[(45?12) HU vs.(90?15)HU,P=0.007]. According to ROC curve,75 HU,with 95.2% sensitivity and specificity,was the critical value for distinguishing the density of parathyroid adenoma and that of thyroid parenchyma. At 35 s following the injection of contrast medium,there was significant difference in the enhancement degree between parathyroid adenoma and lymph node[(182?39) HU vs.(80?20)HU,P=0.004]. According to ROC curve,111 HU,with 95.2 % sensitivity and specificity,was the critical value for distinguishing the density of parathyroid adenoma and that of lymph node 35 s following the injection of contrast medium. At 35 s to 65 s following the injection of contrast medium,the parathyroid adenoma experienced a decline in density,which was dramatically different from parathyroid adenoma,however,lymph node experienced a rise in density. Conclusion Enhanced CT measurements at different time points enable the differentiation among parathyroid adenomas,lymph nodes,and thyroid.