a Biodistribution of 68Ga-labeled CAR T cells within 4 h p.i. in blood, brain, heart, liver, spleen, lung, kidney, muscle, and knee. b Total biodistribution of 68Ga-/89Zr-labeled CAR T cells in the lung, liver and spleen among all solid tissues within 4 h p.i. Values are expressed as the means ± SD (n = 3)