Mediastinal Ga-67 uptake in patients with lymphoma following chemotherapy

Scintigraphic imaging with [67]Ga remains an important tool in evaluating the response of lymphoma to therapy. 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. 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 semi-quantitatively assessed on transaxial sections of thorax Ga-67 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. 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. 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