Normalized spleen/liver ratios on In-111-labelled platelet scintigraphy topredict the outcome of partial splenic embolization in patients with idiopathic thrombocytopenic purpura

In this study, we examined the use of In-111-labelled platelet imaging to p redict the outcome of partial splenic embolization (PSE) in patients with i diopathic thrombocytopenic purpura (ITP). Thirty-eight patients with a clin ical diagnosis of ITP underwent In-111-labelled platelet scintigraphy. Twen ty-four patients with intractable ITP underwent PSE after In-111-labelled p latelet scintigraphy. The conventional spleen/liver ratio at 1 h and 192 h and the normalized spleen/liver ratio [(spleen uptake at 192 h/liver uptake at 192 h) / (spleen uptake at 1 h/liver uptake at 1 h)] were compared betw een responders and nonresponders to PSE. Patients with ITP showed a signifi cant reduction in platelet counts, increased platelet associated IgG, decre ased platelet survival, and an increased conventional spleen/liver ratio at 192 h. No significant difference was found between patients who had and wh o had not undergone previous medical treatment. A significant difference wa s observed in the mean conventional spleen/liver ratio at 192 h between res ponders and non-responders, but there was substantial overlap among individ uals. The mean normalized spleen/liver ratio was significantly higher in re sponders than non-responders; there was less overlap between the two groups with the normalized spleen/liver ratio than the conventional spleen/liver ratio. The therapeutic outcome of PSE is predicted more accurately using a normalized spleen/liver uptake ratio of In-111-labelled platelets in patien ts with idiopathic thrombocytopenic purpura than a conventional splenic/hep atic uptake ratio on delayed images. ((C) 2000 Lippincott Williams & Wilkin s).