PET-CT for evaluation of treatment response in high-grade lymphoma

18F-FDG PET is highly sensitive and specific for evaluation of the treatment response of high-grade lymphomas. The molecular information provided by 18F-FDG-PET identifies the functional content of anatomic finding and helps to categorize their nature as malignant or benign. On the other hand, the CT data obtained in the same setting provides anatomical localization of the 18F-FDG-PET data while also improving the FDG-PET image quality as it is utilized for attenuation correction. Previously, most of the studies were done on this topic by using 18F-FDG-PET alone. Present study was planning to assess the role of 18F-FDG-PET/CT in evaluation of treatment response in patient of HD and NHL. Results showed that 43 patients out of 52 showed no pathologic FDG uptakes, whereas 9 showed persistent uptakes. Among the 43 patients who had negative PET scans, only three relapsed, whereas among the 9 patients who had persistent abnormal 18F-FDG uptakes on post therapy PET/CT scans, two recovered. The sensitivity, specificity, positive and negative predictive values and accuracy of post therapy PET/CT scan was 70%, 95%, 78%, 93%, and 90% respectively. INTRODUCTION The term lymphoma means variety of cancers that affect the lymphatic system. Lymphomas tend to form solid tumors in the body and are often felt as a lump that can occur almost anywhere in the body. There are two major types of lymphomas i.e. Hodgkin’s disease and NonHodgkin’s lymphoma. NHL is a large group of cancers of the immune system. NHL can occur at any age and are often marked by enlarged lymph nodes, fever, and weight loss. There are many different types of NHL, which can be divided into aggressive (fast-growing) and indolent (slow-growing) types and can be classified as either B-cell or T-cell NHL. B-cell NHLs include Burkitt lymphoma, diffuse large B-cell lymphoma, follicular lymphoma, immunoblastic large cell lymphoma, precursor B-lymphoblastic lymphoma, and mantle cell lymphoma. T-cell NHLs include mycosis fungoides, anaplastic large cell lymphoma, and precursor T-lymphoblastic lymphoma. Lymphomas related to lymphoproliferative disorders following bone marrow or stem cell transplantation are usually B-cell NHLs. In general, the risk factors for NHL include weak immune system, certain infections i.e. human immunodeficiency virus (HIV), Epstein-Barr virus (EBV), Helicobacter pylori: H. pylori (bacteria), Human T-cell leukemia/lymphoma virus (HTLV-1), and Hepatitis C virus, and age more than 60. Most often, these symptoms are not due to cancer. Infections or other health problems may also cause these symptoms. NHL can cause many symptoms i.e. swollen, painless lymph nodes in the neck, armpits, or groin, unexplained weight loss, fever, soaking night sweats, coughing, trouble breathing, weakness, pain, swelling, a feeling of fullness in the abdomen.1 The stage is based on where lymphoma cells are found (in the lymph nodes or in other organs or tissues). The stage also depends on how many areas of immune system are affected. (Fig 1) The treatment option for NHL patients, depend upon a variety of factors including the grade of the lymphoma (low, intermediate, or high); the stage or extent of spread of the disease, the areas of the body affected by the lymphoma, and the general health of the patient. In general, the treatment options range from “watchful