The Role Of High Resolution CT (HRCT) In Diagnosis Of Solitary Pulmonary Nodule

The criteria of malignant nodules are : Minute scattered calcification within the nodule suggesting its malignant nature.• The larger the nodule; the more malignant lesion is suspected.• Malignant nodules have rapid growth measuring by doubling time ( large cell carcinoma has the shorter doubling time , then squamous cell carcinoma then adenocarcinoma ).• The margins of malignant nodules are usually irregular with corona radiate sign highly associated with malignancy to lesser extent lobulated and scalloped margins has intermediate probability of malignancy.• Air bronchogarm seen mostly with malignant nodules specially with bronchoalveolar and adenocarcinoma.• Some malignancy such as liposarcoma and renal cell carcinoma are seen with fat content within the nodule.The criteria of benign nodules are: Diffuse , central , popcorn calcifications are pattern of benign patterns of nodules. The smaller the nodule ; the more benign lesion is suspected. Benign nodules are usually stable in size . The margins of benign nodules is usually smooth. Demonstration of fat content within the solitary pulmonary nodule suggest its benign nature and easily determined in hamartoma and lipoma. CT Halo sign suggest the benign nature of nodule seen mainly with infective cause especially with Aspergillus to lesser extent with T.B. , CMV and Herpes simplex.Feeding vessel seen more with benign nature mostly with AVmalformation and septic embolism.