Superior specificity of Ig-HTS compared with PET/CT. (A) A comparison of the sensitivity and specificity of Ig-HTS and PET/CT in patients who had both tests performed during clinical surveillance, with the performance assessed by ultimate clinical outcome of the patient. PET/CT can be seen to have superior sensitivity to Ig-HTS, but the specificity of Ig-HTS was 100% and greater than that of PET/CT. (B-D) Examples of false-positive PET/CT scans with concurrent true-negative Ig-HTS. (B) A PET/CT of a patient in remission from stage IV DLBCL showed a positive signal at the site of previous disease (left, white arrow). Biopsy showed unremarkable fibro-adipose tissue. (C) A patient in remission from stage IV DLBCL with a positive PET/CT in the lungs (left) resulting from granulomatous inflammation (right). (D) A PET/CT of a patient in remission from stage IV DLBCL with signal in a para-aortic lymph node (left) that was shown to result from granulomatous lymphadenitis (right).