Effect of Aging and Diffuse Chronic Pancreatitis on Pancreas Elasticity Evaluated using Semiquantitative EUS Elastography

Abstract

Purpose: Endosonographic elastography has been introduced as a method of estimating the stiffness of pancreatic tumors. This prospective single-center study was conducted to evaluate changes in the stiffness of the pancreas related to age and diffuse chronic pancreatitis.

Patients and Methods: 46 individuals each up to age 60 (group 1) and over age 60 (group 2) with healthy pancreata and 26 patients with diffuse chronic pancreatitis (group 3) were included. Three elastograms were obtained in each case by endosonography in a defined section through the pancreatic body. Elastograms were further evaluated by histogram analysis. Mean strain values, based on a range from 0 (hardest) to 255 (softest), and their standard deviation were calculated from the histogram. The three groups were compared statistically with regard to pancreatic stiffness. A cut-off level for the diagnosis of chronic pancreatitis was defined by testing receiver operating characteristics curves.

Results: The strain values (mean, SD) measured in the pancreatic body in groups 1 – 3 were 110.2 (23.9), 80.0 (16.4), and 32.4 (11.9), respectively. Pairwise comparison of the groups revealed highly significant differences (p < 0.001). At a cut-off value of 50, the area under the curve was 0.993 for distinguishing between chronic pancreatitis and healthy pancreata in people aged over 60.

Conclusion: Semiquantitative elastography shows that pancreata become significantly harder during aging, but remain softer than in chronic pancreatitis. A cut-off value of 50 is suggested as a possible diagnostic criterion for diffuse chronic pancreatitis.

Zusammenfassung

Ziel: Studien zur endosonografischen Elastografie haben sich bislang überwiegend mit der Charakterisierung von Tumoren beschäftigt. In dieser monozentrischen prospektiven Studie haben wir untersucht, ob die Elastografie Änderungen der pankreatischen Gewebshärte infolge des Alterns und diffuser chronischer Pankreatitis nachweisen kann.

Patienten und Methoden: 46 Pankreasgesunde bis einschließlich 60 Jahre (Gruppe 1) oder über 60 Jahre (Gruppe 2) und 26 Patienten mit diffuser chronischer Pankreatitis (Gruppe 3) wurden untersucht. Bei jedem Probanden wurden drei Elastogramme eines endosonografischen Längsschnittes durch das Pankreaskorpus angefertigt. Mittels Histogrammanalyse wurde der mittlere Dehnungswert mit Standardabweichung bestimmt, wobei 0 die niedrigste und 255 die höchste Dehnbarkeit repräsentiert. Die drei Gruppen wurden auf Unterschiede der Dehnungswerte getestet. Mittels ROC (receiver operating characteristics)-Kurven wurde der beste cut-off-Wert für die Diagnose einer chronischen Pankreatitis ermittelt.

Ergebnisse: Die mittleren Dehnbarkeitswerte (Standardabweichung) waren in Gruppe 1 110,2 (23,9), in Gruppe 2 80,0 (16,4) und in Gruppe 3 32,4 (11,9). Alle Gruppen waren im paarweisen Vergleich signifikant verschieden (p < 0,001). Im Vergleich der Ergebnisse bei chronischer Pankreatitis mit den härteren Pancreata der älteren Gesunden zeigte die ROC-Kurve bei einem Wert unter 50 das größte Areal unter der Kurve (0,993).

Zusammenfassung: Semiquantitative Elastografie mittels Histogrammanalyse kann nachweisen, dass gesunde Pankreata mit zunehmendem Alter härter werden, aber weicher bleiben als bei chronischer Pankreatitis. Ein Dehnungswert unter 50 könnte ein diagnostisches Kriterium der chronischen Pankreatitis werden.

Key words

elastography - chronic pancreatitis - aging - endosonography

• References

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