MARROW VERSUS INFECTION IN THE CHARCOT JOINT - IN-111 LEUKOCYTE AND TC-99M SULFUR COLLOID SCINTIGRAPHY

This study evaluated the role of combined leukocyte/marrow scintigraph y in the assessment of the neuropathic or Charcot joint, Methods: Seve nteen patients with In-11-labeled leukocyte accumulation in 20 radiogr aphically confirmed Charcot joints underwent Tc-99m-sulfur colloid mar row scintigraphy. Studies demonstrating labeled leukocyte accumulation without corresponding activity on marrow images were-classified as po sitive for osteomyelitis, Six of the patients also underwent three-pha se bone scintigraphy, Bone scans were interpreted as positive for oste omyelitis when focal hyperperfusion, focal hyperemia and focal bony up take on delayed images were present, Bone images were also interpreted together with labeled leukocyte images using two different criteria f or a positive study, One criterion was the presence Of labeled leukocy te activity in a region demonstrating abnormal activity on the bone sc an, which was more intense than adjacent marrow activity or marrow act ivity in the corresponding region of the contralateral foot, The secon d criterion was either a spatially incongruent distribution of the two tracers or hyperintense activity on the leukocyte study, as compared to the bone scan. Results: Leukocyte/marrow studies were positive for osteomyelitis in 4 of the 20 neuropathic joints. Osteomyelitis was pre sent in three of the four joints, whereas in the fourth, infection was confined to overlying soft tissues, None of the 16 neuropathic joints with negative leukocyte/marrow scans were infected, In one patient wh o underwent below-the-knee amputation, histological analysis confirmed the presence of hematopoietically active marrow corresponding to area s of congruent activity on the leukocyte and marrow images. Three-phas e bone scintigraphy was positive in all six neuropathic joints studied ; osteomyelitis was present in two of them. Using the first criterion, leukocyte/bone imaging was also positive in all six. Using the second criterion, leukocyte/bone imaging was positive in the two infected ne uropathic joints, as well as in three uninfected ones, Leukocyte/marro w scintigraphy was positive in both infected joints and negative in th e four without infection; Conclusion: Labeled leukocyte accumulation i n the uninfected Charcot joint does occur and is related, at least in part, to hematopoietically active marrow. Leukocyte/marrow scintigraph y is a reliable way to differentiate between marrow and infection as t he cause of labeled leukocyte accumulation in the neuropathic joint an d, in this series, was superior to both three-phase bone scintigraphy and combined leukocyte/bone scintigraphy.