67Ga citrate versus 99mTc-labeled LL2-Fab' (anti-CD22) fragments in the staging of B-cell non-Hodgkin's lymphoma.

The value of 67Ga citrate scanning as a transferrin receptor agent was compared in this study with a 99mTc-labeled anti-CD22 (B-cell) Fab' fragment (LL2) in patients with low- and high-grade B-cell non-Hodgkin's lymphoma (NHL). Thirteen patients with histologically confirmed NHL were examined prospectively with both radiopharmaceuticals within 8 days. The results of immunoscintigraphy were compared with those of 67Ga scanning and the clinical and radiological workup (computed tomography, ultrasound, and magnetic resonance imaging) of the patients. The overall sensitivity of 67Ga citrate and 99mTc-labeled LL2 fragment was each 80% in a total of 43 lesions. Low-grade lymphoma patients had a higher sensitivity in LL2 imaging (82% versus 71%), and high-grade lymphoma patients in 67Ga citrate scanning (100% versus 75%). The target:background ratio in low-grade NHL for LL2 was 1.43 +/- 0.3:1 versus 1.8 +/- 0.5:1 in 67Ga scans; in high-grade NHL, 1.49 +/- 0.35:1 versus 2.2 +/- 0.8:1, respectively. Single-photon emission computed tomography imaging was necessary in 21.7% of the patients 4 h after injection to localize the lesions. In conclusion, the overall sensitivity of 99mTc-labeled LL2 is comparable to 67Ga citrate scanning in patients with B-cell NHL. 99mTc-labeled LL2 antibodies are rapid to use, are safe, and need a shorter imaging time (24 h versus 72 h). Because of these advantages, 99mTc-labeled LL2 may be superior to 67Ga scanning for the staging of lymphoma patients.