The use of radionuclide-labeled white blood cell scintigraphy and ⁶⁷gallium scintigraphy in critically ill patients with sepsis

The usual diagnostic approach to patients with sepsis in an intensive care unit (ICU) or coronary care unit is based on clinical, biochemical, microbiologic and pathologic data and on radiologic imaging (radiograph, ultrasound and computed tomography), which are used to determine the most common sites of infection. In many cases, however, the site of infection is difficult to determine. Nuclear medicine provides various noninvasive scintigraphic methods for the imaging of focal sepsis, based on the intravenous administration of a radiotracer that accumulates at the site of infection or inflammation. The combined use of total body scintigraphy with ultrasound and computed tomography is considered a useful tool for the diagnosis of occult sepsis in ICU patients, and allows the targeting of aggressive measures against infections. The aim of this study is to evaluate the diagnostic value of technetium 99 m-white blood cell (^99mTc-WBC)-labeled scintigraphy and gallium-67 citrate (⁶⁷Ga) scintigraphy in the detection of focal sepsis in the ICU. We reviewed seven patients affected by sepsis of unknown origin. After the usual diagnostic approach, five patients were submitted to a total body scan using the ^99mTc-WBC and two patients using ⁶⁷Ga. The patients had complete clinical and instrumental data, but none of the radiological image detected the site of infection. The ^99mTc-WBC scan showed typical patterns of increased tracer accumulation in six different sites. Four of these sites were studied histopathologically, confirming the infection: one case of left kidney abscess was associated with concomitant infection of the psoas muscle in the same patient, one frontoparietal osteomyelitis, and one acute cholecystitis. The other two sites corresponded to pulmonary accumulation of the tracer, which was interpreted as pneumonia. Of the two patients who underwent ⁶⁷Ga scintigraphy, one had decubitus ulcerated infection associated with sacrum and left femoral osteomyelitis, and the other had clinical suspect of pulmonary vasculitis and diffuse pulmonary ⁶⁷Ga accumulation.

Conclusions

Analysis of our results suggests that scintigraphy with ^99mTc-WBC and ⁶⁷Ga can be considered a powerful tool in the detection of the source of infection in patients with sepsis in the ICU and the coronary care unit.