IS COMPUTER-AIDED INTERPRETATION OF TC-99(M)-HMPAO LEUKOCYTE SCANS BETTER THAN THE NAKED EYE

In order to compare visual interpretation of inflammation detected by leukocyte scintigraphy with that of different computer-aided quantific ation methods, 34 patients (25 with ulcerative colitis and 9 with endo scopically verified non-inflamed colonic mucosa), were investigated us ing Tc-99(m)-hexamethylpropyleneamine oxime (Tc-99(m)-HMPAO) leukocyte scintigraphy and colonoscopy with biopsies. Scintigrams were obtained 45 min and 4 h after the injection of labelled cells. Computer-genera ted grading of seven colon segments using four different methods was p erformed on each scintigram for each patient. The same segments were g raded independently using a 4-point visual scale. Endoscopic and histo logical inflammation were scored on 4-point scales. At 45 min, a posit ive correlation was found between endoscopic and scan gradings in indi vidual colon segments when using visual grading and three of the four computer-aided methods (Spearman's r(s)=0.30-0.64, P<0.001). Histologi cal grading correlated with visual grading and with two of the four co mputer-aided methods at 45 min (r(s)=0.42-0.54, P<0.001). At 4 h, all grading methods correlated positively with both endoscopic and histolo gical assessment. The correlation coefficients were, in all but one in stance, highest for the visual grading. As an inter-observer compariso n to assess agreement between the visual gradings of two nuclear physi cians, 14 additional patients (9 ulcerative colitis, 5 infectious ente rocolitis) underwent leukocyte scintigraphy. Agreement assessed using kappa statistics was 0.54 at 45 min (P<0.001). Separate data concernin g the presence/absence of active inflammation showed a high kappa valu e (0.74, P<0.001). Our results showed that a simple scintigraphic scor ing system based on assessment using the human eye reflects colonic in flammation at least as well as computer-aided grading, and that highly correlated results can be achieved between different investigators.