A Feasibility Study of Gallium-68 Citrate PET to Detect Aberrant MYC Proto-Oncogene, BHLH Transcription Factor (MYC) Protein Expression in Diffuse Large B-Cell Lymphoma

Inclusion Criteria: 1. Histologically confirmed DLBCL or BCLU. * Double hit lymphoma, defined by positive cytogenetic/ fluorescence in situ hybridization (FISH) analysis for translocations involving myc and bcl2 or a double hit score of 2 by immunohistochemistry as described by Johnson et al. * DLBCL without myc translocation or overexpression by the above methods 2. Presence of palpable or radiographically measurable disease of at least 1.5 cm in longest dimension. 3. Available prior CT or PET/CT scan done in the last 8 weeks for comparison 4. Prior chemotherapy or radiation to the measurable lesion must be completed at least 14 days prior. 5. Adequate renal function with estimated creatinine clearance ≥50 mL/min (by the Cockcroft Gault equation) 6. No contraindications to MRI (e.g. pacemaker, aneurysm clips, severe claustrophobia) 7. Ability to sign a study-specific internal review board (IRB) approved consent prior to study entry. Patients must be able and willing to consent and undergo study procedures. 8. Age ≥18 years old Exclusion Criteria: 1. Any serious and/or unstable pre-existing medical, psychiatric, or other medical condition that could interfere with subject's safety, provision of informed consent, or compliance with study procedures 2. Body weight over 300 pounds 3. Female patients who are pregnant or breast-feeding 4. Prior MRI with gadolinium performed \<24 hours before the study scan 5. No red blood cell transfusion or iron administration by any route in the last 7 days 6. Prior hypersensitivity or intolerance to gadolinium or gallium citrate.