Comparison And Analysis Of CT And Ultrasonography Findings Of Benign And Malignant Thyroid Nodules

Objective:The importance of the diagnosis for thyroid nodules is to distinguish benign and malignant nodules. Early detection of lesions and identification of their benignant and malignancy are of great significance for clinical treatment and prognosis improvement. Ultrasound and computed tomography (CT) are the most important and common imaging examination means for thyroid,which can clearly show the morphological structure of thyroid nodule,and it’s size,border, internal echo, cystic change,calcification, reinforcement, or blood flow,as well as the structure surrounding the thyroid, neck lymph nodes and so on. There are reported literature for each of the identification of benign and malignant thyroid nodules, but there are no literature to compare two examination methods.The CT and ultrasonographic findings of the thyroid nodules were contrastively analyzed and the key point of the differential diagnosis of thyroid nodules and the difference between this two imaging modalities were investigated to increase the accuracy of the diagnosis of the thyroid nodules.Methods:Information of896patients (1398thyroid nodules) confirmed by pathology were collected.All patients above were with preoperative ultrasound examination, postoperative pathological results, among whom337patients (455nodules) received CT scan and contrast-enhanced scan in the same time. Color doppler ultrasonic detector was used in ultrasound examination, whose frequency was7.5MHz,20MHz.16CT for CT examination whose section thickness was3mm and section gap was3mm, had scan firstly and did contrast-enhanced scan later.Contrast medium dose was1.5ml/kg.The flow rate for the injection of contrast media was3ml/sec.The time of delay phase in contrast-enhanced scan was60seconds.CT and ultrasound images were double-blindly analyzed by2high-qualification doctor, and researched by comparing with pathology results. Image analysis including: nodules location, shape, maximum diameter, cystic change, calcification, reinforcement, blood flow, edge and thyroid capsule. SPSS16.0software was used for data management and analysis,and P<0.05was statistically significant.Results:Of896patients,234male and622female(M:F=1:2.83), whose proportion of benign and malignant had no statistical difference (p>0.05). The average age of the patients (47.71±12.26years old) with benign nodules was greater than patients (43.81±12.69years old) with malignant nodules (p=0.000). Left thyroid lobe, right thyroid lobe and isthmus,where the incidence of nodules and the proportion of benign and malignant had no statistical difference (p>0.05). Significant statistical difference was found between the diameter of benign nodules (21.20±6.04mm) and malignant nodules (13.67±10.17mm)(P=0.000). The correlation coefficient between biggest diameter and malignancy is0.335. The malignant rate of nodules with cystic component (10.6%,32/302) was far lower than that of solid nodules (46.1%,505/1096)(P=0.000). There was only1malignant nodule in80completely cystic nodules. Calcific rate of malignant nodules (53.3%,286/537) were higher than benign nodules (22.6%,195/861)(P=0.000). Microcalcification was found in29.6%(159/537)malignant nodules and7.8%(67/861)benign nodules with great difference(P=0.000). The detectable rate of calcification and cystic component with CT (25.1%,13.8respectively) were lower than ultrasound (34.4%,21.6%respectively)(p=0.000). The detectable rate of ill-defined margin with CT and ultrasound was respectively40.66%(185/455) and35.19%(492/1398)(p=0.035) while extracapsular extension detectable rate was16.04%(73/455) in CT and only3.36%(47/1398) in ultrasound (p=0.000). Thyroid carcinomas were observed in11.54%(3/26) of nodules without enhancement in CT and in33.00%(299/906) of non intranodular or perinodular vascularity nodules in ultrasound.Morphology of5.2%(45/861)benign nodules and28.3%(152/537) malignant nodules was irregular on ultrasound, the same to5.6%(11/196)benign nodules and23.6%(61/259) malignant nodules on CT examination. The morphology of benign and malignant nodules was statistically difference (P=0.000), but showing nodules morphology through CT and ultrasound had no difference (P=0.362).Conclusions:1、CT excels in showing thyroid capsule and nodule margin than ultrasonography. 2、Ultrasonography is predominant in detecting micro thyroid nodules, calcification and cystic component of thyroid nodules.3、Both CT and ultrasound can provide multiple clues to define the benign and malignant nodules.Differences between benign and malignant thyroid nodules: patient age, thyroid capsule, nodule size, shape, edge, cystic change and calcification, with or without reinforcement (CT), with and without blood flow (ultrasound). There is no difference between benign and malignant thyroid nodules:location, strengthening degree of the nodules (CT), richness degree of blood flow.4、Nodules with cystic change or without reinforcement (blood flow) suggest benign possibility.5、Calcification (especially the tiny calcification) in malignant nodules gets higher incidence.6、Slightly negative correlation is showed between the nodule diameter and malignant probability-bigger nodules, lesser probability of malignancy.The biggest diameter of nodule can be used as identification of the benign and malignant nodules.