Der Beitrag der Bildanalyse für die Differenzialdiagnose der fokalen Nierenparenchymveränderungen

Zusammenfassung

Ziel: Die Quantifizierung der Echointensität könnte einen Beitrag für die Differenzialdiagnose von fokalen Nierenveränderungen leisten. Material und Methoden: Bei 145 Patienten mit fokalen Nierenparenchymveränderungen wurden digitalisierte Bilder ausgewertet (40 Angiomyolipome [A], 70 Nierenzellkarzinome [B], 20 Pseudotumoren [C] sowie 15 andere fokale Veränderungen [D]). Mit Photoshop® wurden die durchschnittlichen Grauwerte der Läsion (definiert als Echointensität, E_F) und deren Varianz s² (als Maß für Inhomogenität, I_F) gemessen. Als Vergleich diente die umgebende Nierenrinde. Berechnet wurden Echointensitätsquotient, Echointensitätsindex, Inhomogenitätsquotient und Inhomogenitätsindex. Ergebnisse: Angiomyolipome hatten einen höheren Echointensitätsquotient E_Q und Echointensitätsindex E_I als Nierenzellkarzinome, Pseudotumoren sowie andere Läsionen (p < 0,001). Pseudotumoren hatten einen niedrigeren Inhomogenitätsquotienten I_Q als Angiomyolipome (p < 0,001) und Nierenzellkarzinome (p < 0,05). Ein Echointensitätsquotient ≥ 2,0 und Echointensitätsindex ≥ 0,5 waren typisch für Angiomyolipome; bei Tumoren < 3 cm lag die Sensitivität bei 96,4 %, Spezifität bei 97,3 %. Schlussfolgerung: Die quantitative Echointensitätsmessung objektiviert die Differenzialdiagnose fokaler Nierenveränderungen. Die Unterscheidung typischer Angiomyolipome von anderen Läsionen wird dadurch erleichtert.

Abstract

Purpose: Visual analysis of echo intensity is of importance for the differential diagnosis of focal renal lesions. Quantification of the echo intensity and of other parameters might help with differential diagnosis. Materials and Methods: In 145 patients with focal renal lesions, digitized images were evaluated (40 angiomyolipomas [group A], 70 renal cell carcinomas [group B], 20 pseudo-tumors [group C] and 15 other focal lesions in group D). With Photoshop®, the average grayscale values of the lesion (defined as echo intensity focal, E_F) and its variance s² (as expression of the inhomogeneity focal, I_F) were measured. These measurements were compared to the renal cortex (echo intensity renal cortex = E_R, inhomogeneity renal renal cortex = I_R). Other calculated parameters: Echo intensity quotient, echo intensity index, inhomogeneity quotient and inhomogeneity index. Results: Angiomyolipomas had a higher echo intensity quotient E_Q and echo intensity index E_I than renal cell carcinomas, pseudo-tumors and other lesions (p < 0.001). Pseudo-tumors had a lower inhomogeneity quotient than angiomyolipomas (p < 0.001), renal cell carcinomas (p < 0.05). Echo intensity quotient E_Q ≥ 2.0 and echo intensity index E_I ≥ 0.5 were typical for angiomyolipomas with a sensitivity of 96.4 % and a specificity of 97.3 % for tumors < 3 cm. Conclusion: Quantitative echo intensity measurements enhance the differential diagnosis of focal renal lesions. The differentiation of typical angiomyolipomas to other lesions could be improved.

Key words

abdomen - ultrasound - neoplasms

Literatur

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