Expected biodistribution show the following:
• Easily detectable uptake in blood-pool areas on first image, with less activity in blood-pool areas on second or third image
• Moderately high or high uptake in normal liver and spleen during first and second or third image
• Moderately low or very low uptake in normal kidneys, lungs, urinary bladder, and normal bowel on first and second or third image
• Localization to lymphoid aggregates in bowel wall has been reported
• Tumor uptake may be visualized in soft tissues as areas of increased intensity, and tumor-bearing areas in normal organs may be seen as areas of increased or decreased intensity
Altered biodistribution are met if any of the following is detected:
• Rapid clearance of radioimmunoconjugate from blood pool, with prominent liver, spleen, or marrow uptake on first image
• Diffuse uptake in normal lung more intense than cardiac blood pool on first image or more intense than liver on second or third image
• Kidneys with greater intensity than liver on posterior view of second or third image
• Intense areas of uptake throughout normal bowel comparable to uptake by liver on second or third image
Whole-body g-camera images obtained at 4 and 68 h after administration of 111In-ibritumomab tiuxetan, showing expected biodistribution, with the radiopharmaceutical easily detectable in the blood-pool areas on 4-h images. Moderately high or high uptake in normal liver and spleen is seen on 4- and 68-h images, and moderately low or very low uptake in normal kidneys, urinary bladder, and bowel is seen on 4- and 68-h images. Tumor uptake is seen in mediastinal lymph nodes.
Whole-body g-camera images of representative patients obtained at 24 h after administration of 111In-ibritumomab
tiuxetan (A), showing prominent bone marrow and splenic uptake, and at 3 and 48 h after administration of 111In-ibritumomab tiuxetan (B), showing greater than expected renal uptake.