Comparison of contrast-enhanced CT, PET/CT, PET, and low-dose non-contrast enhanced CT imaging of diffuse large B-cell (DLBCL), follicular (FL), small lymphocytic/CLL (CLL/SLL), and marginal zone lymphomas (MZL).

Abstract

8079 Background: Anatomic imaging by contrast-enhanced computed tomography (CECT), functional imaging by 18FDG- PET (PET), and low-dose non-contrast enhanced CT (NECT) co-registered with PET (PET/CT) is used for detection of lymphomas. We compared the sensitivity of detection of specific lymphomas for each of these imaging modalities. Methods: Patients (pts) with DLBCL, FL, CLL/SLL, or MZL with PET/CT and CECT studies performed at our institution within 6 weeks of each other without intervening therapy were studied. Radiologists, blinded to clinical information and other imaging results, separately interpreted image sets of NECT, PET, fusion PET/CT, and CECT studies. The presence or absence of disease at 44 nodal and 48 (female) / 49 (male) extranodal sites was recorded for each site for each imaging modality. Concordant findings across imaging modalities were defined as positive for involvement by lymphoma; discordant findings were reconciled using all available clinical and radiologic information with follow-up for progression or regression of abnormality, or by biopsy. Results: 56 pts with DLBCL (n=31), FL (n=13), CLL/SLL (n=5), and MZL (n=7) had image sets available for review; 305 sites met criteria for involvement by lymphoma (DLBCL = 89, FL = 98, MZL = 45, CLL/SLL = 73). PET/CT had a higher sensitivity of lymphoma detection than CECT in DLBCL (difference in sensitivity 28% [95%CI 15-40], p < 0.0002) and FL (difference in sensitivity 12% [95%CI: 1-23], p = 0.02). CECT had a higher sensitivity of lymphoma detection than PET/CT in MZL (difference in sensitivity 18% [95%CI 1-34], p = 0.035) and CLL/SLL (difference in sensitivity 34% [95%CI 19-48], p < 0.0002). CECT had a higher sensitivity than NECT in FL (difference in sensitivity = 26% [11-38], p < 0.0002), MZL (difference in sensitivity 22% [95%CI 5-38], p = 0.011), and CLL/SLL (difference in sensitivity = 25% [95%CI 5-38], p < 0.0004), but not in DLBCL. Conclusions: The optimal modality for imaging lymphoma depends on the specific lymphoma. For DLBL and FL, PET/CT is superior to CECT. Conversely, CECT is superior to PET/CT imaging in CLL/SLL and MZL. No significant financial relationships to disclose.