In vivo imaging of myeloma tumor xenografts after MV infection. In panel A, an ARH-77 tumor in a mouse injected intravenously with MV-Edm does not concentrate ¹²³I and gives no signal on the gamma camera 9 days after virus administration. Injection of MV-NIS in mice with MM1 (B), ARH-77 (C), and KAS-6/1 (D-F) tumors led to NIS expression and ¹²³I uptake by the tumors in vivo 9 days after virus administration. Serial imaging of mice with KAS-6/1 tumors on days 3 (D), 9 (E), and 17 (F) after a single injection of MV-NIS shows changes in iodide uptake due to viral and tumor cell replication. All images are adjusted for equal background and were acquired over a 5-minute exposure. The large arrows point to the myeloma tumor xenografts in the right flanks of the mice. Magnification is 0.55 mm per pixel.