Mediastinal Ga-67 Uptake in Patients with Lymphoma Following Chemotherapy

Background: Scintigraphic imaging with 67Ga remains an important tool in evaluating the response of lymphoma to therapy.Aim of the Study: Scintigraphic characteristics of lung hilar Ga-67 uptake (HU) and their relationship with the etiology (benign vs. malignant) of the hilar lesions in lymphoma patients following chemotherapy were retrospectively investigated.Patients and Methods: A total of 161 lymphoma patients were included in the study. The presence/absence of HU and if present, symmetry/asymmetry and intensity of HU (on the basis of a 3 scale grading system) were visually and semiquantitatively assessed on transaxial sections of thorax Ga67 SPECT. By drawing ROIs over right and left hilum, asymmetry index (AI%) was also calculated. HU was categorized as benign or malignant depending on the radiological correlation and clinical follow-up. Results: In the malignant group, the majority of patients (85.7%) had grade 2 or grade 3 uptake and all had asymmetric pattern. However, in the benign group, grade 1 uptake was more common (66%) and was mainly symmetric (94.6%) in appearance. AI% in the malignant group (73.7±36.6) was significantly higher than in the benign group (5.7±4.9) confirming the marked asymmetry in malignant patients.Conclusion: Lung HU is a common finding in patients with lymphoma following chemotherapy and frequently benign in origin, particularly if HU is symmetric and its intensity is less than that of sternum. Asymmetry index (AI%) as proposed in the present study can be used when visual assessment for the symmetry of HU is inconclusive.