45the articular surface. In addition, patients may develop bone infarction, which is
seen as various areas of abnormal signal intensity within the bone on MR [ 2 ].
3.2.3 Radionuclide Imaging for Patients Undergoing
Hematopoietic Stem Cell Transplantation (HSCT)
Unfortunately, there is scant literature describing the use of radionuclide imaging
for localization of infections in patients who are preparing to undergoing
HSCT. Primarily, articles describe the use in the initial diagnosis and for other
assessment of the disease status, or there are text book descriptions and illustrations
of specific instances of use [ 7 – 9 ]. In the past though, radionuclide imaging was an
important step in identifying potential infections in children with immunodeficien-
cies prior to HSCT. Localization and appropriate treatment was necessary to attain
success with HSCT. If a hidden infection was present, and the child received mye-
loablative chemotherapy, severe life-threatening infectious complications could
ensue. The standard approach would be to perform a Technetium-99 m or Gallium
67 scan for localization of sites of inflammation and potential infection. Occasionally,
these would be performed in tandem, a few days apart, to allow the previous radio-
nuclide to decay. Alternatively, a “tagged-white cell scan” (indium-111 scan) would
be used, with the patient’s “tagged-neutrophils” migrating to the potential site of
infection. Initially, the radioactive emissions would be captured on 2-dimensional
radiographic film or on a scanner plate. The potential site of inflammation or infec-
tion could be approximately located, and then a subsequent ultrasound or CT scan
Fig. 3.8 Posterior
reversible encephalopathy
syndrome (PRES) 6 weeks
after transplantation. Axial
FLAIR image shows
occipital hyperintensity in
the typical distribution of
PRES (arrows)
3 Radiologic Procedures Used in Pediatric Stem Cell Transplantation