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  Indian J Med Microbiol
 

Figure 9: A patient with known diffuse large B cell lymphoma of lung on staging positron emission tomography/computed tomography (PET/CT) (a) was treated with two cycles of rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone (RCHOP) chemotherapy and subjected to PET/CT for interim response assessment. Maximum intensity projection image (b) shows a reduction of fluoro-deoxy-glucose (FDG) uptake from 12.0 to 7.0 and reduction in extent suggesting partial response (PR). However, new FDG avid lymph nodes are noted in the anterior mediastinum (c) but not seen in staging study (d). According to any interpretation criteria new lesion suggestive of lymphomatous involvement should be considered as progressive disease and the patient should be labeled as a progressor. However in this patient the initial chemotherapy was started after a 2 months delay of staging PET/CT that might have led to increase in volume of disease prior to chemotherapy. So the study was interpreted as PR. Later the patient completed six cycles of chemotherapy and achieved PR at the end of therapy and did not progress over a follow-up period of 2 years. This image highlights the role of careful history taking and clinical correlation with respect to chemotherapy timing to avoid false positive interpretations during reading of interim PET/CT studies

Figure 9: A patient with known diffuse large B cell lymphoma of lung on staging positron emission tomography/computed tomography (PET/CT) (a) was treated with two cycles of rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone (RCHOP) chemotherapy and subjected to PET/CT for interim response assessment. Maximum intensity projection image (b) shows a reduction of fluoro-deoxy-glucose (FDG) uptake from 12.0 to 7.0 and reduction in extent suggesting partial response (PR). However, new FDG avid lymph nodes are noted in the anterior mediastinum (c) but not seen in staging study (d). According to any interpretation criteria new lesion suggestive of lymphomatous involvement should be considered as progressive disease and the patient should be labeled as a progressor. However in this patient the initial chemotherapy was started after a 2 months delay of staging PET/CT that might have led to increase in volume of disease prior to chemotherapy. So the study was interpreted as PR. Later the patient completed six cycles of chemotherapy and achieved PR at the end of therapy and did not progress over a follow-up period of 2 years. This image highlights the role of careful history taking and clinical correlation with respect to chemotherapy timing to avoid false positive interpretations during reading of interim PET/CT studies