Application Of 320-slice CT In Thyroid Morphology Analysis And Differential Diagnosis Of Nodules

ObjectiveThis study is to discuss the application value of 320-row CT in the differential diagnosis of benign and malignant thyroid nodules and surgical therapy under the guidance of the following findings: a) a normal reference range by summing up the CT findings of thyroid and its surrounding structures of healthy Chengdu locals and b) summary ofthe CT features of different pathological thyroid nodules and filtering differential diagnostic indicators. Materials and MethodsThe first part of the study is a retrospective analysis of 161 cases of cervical CT angiography images by observing the features of thyroids of healthy local adults, including morphology, size, density and blood supply and the different performances varying with lobes, gender and age. In addition, the researcher also tries to find the thyroid’s normal relations with the fat space, vessels, trachea and bone structure around it by combining the images with the CT reconstruction technique, trying to recognize the anatomic landmarks of the important vessels and nerves across the region.In the second part, the researchers have made a comparative analysis of the 320-row CT scan images and pathological findings of 46 cases of thyroid nodules, a total of 48 nodules. The observation targets include nodule’s size, number, texture(solid or cystic), shape, margin, capsule, calcification, CT density value, enhancement degree and enhancement pattern; the number and morphology changes of small blood vessels supplyingto thyroid nodules, the change in the surrounding space; the size, shape and contrast enhancement characteristics of cervical lymph nodes. This is to explore the relevance between thyroid nodules and the CT manifestations. Results1. The anteroposterior diameterand width of thyroid vary greatly with gender and sides of lobesamong the Chengdu local population, the measurements of the male greater than those of the female; the height of thyroid varies greatly withgender and age, the measurements of the male greater than those of the female, and the measurements negatively correlated with age. The thickness of isthmus is uncorrelated with age or gender.2. The CT scan images of thyroid show statistical difference in density value among lobe and age variations, the values of 38-47- year-old grouparethe highest. The absolute enhancement value in arterial and venous phase vary greatly withgender and sides of lobe, the measurements of the female being greater than those of the male; statistical difference of the relative enhancementvalue in arterial and venous phase has not been found among different groups.3. Images of 320-row CT scan and enhanced CT scan can reveal the presence, quantity, beginning and ending of the superior thyroid artery, inferior thyroid artery and inferior thyroid vein; they can also show the space around the thyroid capsule, the space around the esophagus and the trachea, the space around the cervical vessels and their appearances.4. Differences between benign and malignant nodules have been found in the shape, density value of normal CT scan and enhanced CT scan, relative enhancement value, margin and enhancement patterns. Irregular shape, lower density, more pronounced relative enhancement, heterogeneous enhancement and unclear border in enhanced CT scan indicate greater chance of malignancy; lymph node metastasis and infiltration are usually definite signs of malignancy.5. 320-row CT scan plus enhanced CT scan can demonstrate the nodule’s location, size, infiltration range, the surrounding situation, the small blood vessels and new blood vessels and cervical lymph node metastasis. Conclusion1.320-row CT is featured by high resolution and powerful reconstruction function. Therefore, it has technologicaladvantages in analyzing morphological characters of thyroid.2. The morphological characteristics of healthy thyroid vary with lobes, gender and age. Therefore, we should refine the normal reference range according to these variations.3. Thyroid nodules CT findings have guiding significance to differential diagnosis of benign and malignant thyroid nodules. It is helpful for the subsequent diagnosis and treatment, especially the initial diagnosis of incidental thyroid nodules.4. 320-row CT Scan plus enhanced CT scan has a special advantage for observing the surrounding structures of thyroid. It is helpful for tumor staging and making operation scheme. A pre-surgery enhanced CT exam is recommended.5. The effective dosage of radiation used in 320-row CT thyroid scanning, 3.15±0.11 mSv, is low. Therefore, it is questionable to put too much emphasis on the impact of ionizing radiation of CT but despising its utility value.