The Role of Positron Emission Tomography/Computed Tomography (PET/CT) in Assessment of Therapeutic Response in Non-Hodgkin Lymphoma

Abstract
Background: Lymphoma is the most common primary hematopoietic malignancy, make up a heterogeneous group of neoplastic diseases of lymphocytes origin broadly divided into Hodgkin Disease (HD) and Non-Hodgkin's Lymphoma (NHL) In the past decade, functional imaging with 18F-FDG PET has been the fastest growing diagnostic modality in oncology, the addition of PET to CT adds sensitivity and specificity in tumor imaging. Thus, PET/CT is a more accurate test than either of its individual components.
Aim of Study: This study was undertaken to evaluate the role the PET/CT in assessment of response to chemotherapy and or radio therapy, follow-up and assessment of remissions and relapses in patients with lymphoma.
Patients and Methods: Retrospective diagnostic interven-tional study in Ain Shams University Hospitals. Study popu-lation: Non Hodgkin lymphoma patients receiving therapy-presenting to Ain Shams University Hospitals since Jan. 2018- Apr. 2019. Patients included will perform one or more of the following: Initial PET/CT for staging and follow-up PET/CT exams. All exams will be done on the PET/CT scanner. intravenous glucose Fluorodeoxyglucose (FDG) dose depend-ing on the protocol of department. After 60min of 18F-FDG injection MCDT diagnostic nonionic contrast examination for anatomical localization followed by PET images. The whole study took approximately 20-30 minutes.
Results: This study included 20 patients with pathologi-cally confirmed non Hodgkin lymphoma (diffuse large B cell) who underwent PET/CT study after they had finished their treatment protocol. The PET/CT exam of each patient was interpreted for the assessment of treatment response after end of treatment. About 65% of patients received 6 cycles of chemotherapy, however only 35% received 8 cycles of chem-otherapy.
In our study, 12 patients (60%) had extra-nodal involve-ment and were as follow: 7 patients (55%) had only one extra nodal affection site and 5patients (45%) had more than one extranodal affection site. It had high sensitivity (100%) and specificity (75%) for the evaluation of therapeutic response than contrast enhanced CT and fair agreement (Kappa 0.610) according to the Deauville criteria. We assess therapeutic response in our study using IHP and correlated with visual assessment using (Deauville Criteria-five-point scale).
Conclusion: Combined PET/CT using 18F-FDG is the best oncologic imaging modality at present time with indis-pensable role and valuable application in management of lymphoma. According to the Deauville criteria in end of treatment response assessment. We recommend in reporting of PET-CT for response assessment using the Deauville criteria.