Three-phase white blood cell scan: diagnostic validity in abdominal inflammatory diseases

Indium-111-oxine saline-labeled "mixed" leukocyte (n = 16) and "pure" granulocyte (n = 66) scans were prospectively performed as "three-phase" white blood cell (WBC) scans (imaging: 30 min, 4 hr, and 24 hr after reinjection of the cells) in 82 patients suspected of having abdominal or retroperitoneal abscesses or inflammatory lesions. Inflammation was verified histologically, endoscopically, radiologically or by autopsy in 51 and excluded in 31 patients. Sensitivity, specificity, and diagnostic accuracy of the 30-min scan (90%, 56%, 72%) were statistically significantly lower than the 4-hr scan (96%, 97%, 98%). Of the 24-hr scan sensitivity, specificity, and diagnostic accuracy were only 84%, 98%, and 89% because many patients with chronic inflammatory bowel diseases had excreted a portion of intestinal 111In activity by 24 hr. The overall sensitivity, specificity, and accuracy of the "three-phase" WBC scan were 98%, 97%, and 98%, respectively. Only one female patient showed a false-positive scan with granulocyte uptake in an ulcerating adenocarcinoma of the colon. The 4-hr scan or the three-phase study are recommended because of their high sensitivity, specificity, and excellent diagnostic accuracy (98%). The 30-min scan is less specific (56%); the 24-hr scan less sensitive (84%). The three-phase study additionally allows the differentiation between inflammatory bowel diseases and abscesses because it allows observation of granulocyte kinetics for 24 hr.