Scintigraphy with 99mTc-labeled heat-altered erythrocytes in diagnosing hyposplenia: prospective comparison to 99mTc-labeled colloids and colour-coded duplex ultrasonography.

AIM

Ultrasound may be a cheap alternative to scintigraphic determination of splenic function. We directly compared nanocolloid scintigraphy (NS), scintigraphy with heat-altered erythrocytes (ES), and colour-coded Doppler sonography (DS) in patients with chronic inflammatory bowel disease (CIBD).

PATIENTS, METHODS: 35 patients were included into the study. Clearance rates were determined in ES, spleen/liver ratios (SLR) were measured scintigraphically in ES/NS. In DS, spleen size, echogenicity, and vascular resistance indices (RI) were determined. The results were compared to each other, to the clinical activity scores for CIBD, and to the course of the disease.

RESULTS

Based on the blood erythrocyte clearance serving as standard, patients had a good (19 patients), impaired (5), or missing splenic function (11). There was a good correlation of the clearance to SLR in ES (0.63, p < 0.01). The 10 min / 45 min ES clearance showed a high correlation (Spearman-Rho 0.87, p < 0.01). The SLR in ES at 2, 5, 10 and 45 min also correlated well with each other (Spearman-Rho > 0.9, p < 0.01; SLR > 3.45 normal splenic function, SLR < 1.22 indicated hyposplenia). There were no correlations between the results of NS, DS, Howell-Jolly-bodies, or clinical parameters. Only ES and the erythrocyte clearance correlated well. Howell-Jolly-Bodies detected 1 of 11 patients with hyposplenia while false-positive in 4.

CONCLUSION

Ultrasound and colloid scintigraphy show a low correlation with clearance of heat-altered erythrocytes. Only ES shows a good correlation in patients with CIBD. The clearance at 10 min already reliably determines splenic function. SLR may be determined after 10 minutes and is predictive of normal function if above 3.45 while SLR < 1.2 indicated hyposplenia.