Computed Tomography Perfusion Analysis of Pancreatic Adenocarcinoma using Deconvolution, Maximum Slope, and Patlak Methods – Evaluation of Diagnostic Accuracy and Interchangeability of Cut-Off Values

Abstract

Purpose The goal of this study was to evaluate the diagnostic accuracy of perfusion computed tomography (CT) parameters obtained by different mathematical-kinetic methods for distinguishing pancreatic adenocarcinoma from normal tissue. To determine cut-off values and to assess the interchangeability of cut-off values, which were determined by different methods.

Materials and Methods Perfusion CT imaging of the pancreas was prospectively performed in 23 patients. 19 patients with histopathologically confirmed pancreatic adenocarcinoma were included in the study. Blood flow (BF), blood volume (BV) and permeability-surface area product (PS) were measured in pancreatic adenocarcinoma and normal tissue with the deconvolution (BF, BV, PS), maximum slope (BF), and Patlak methods (BV, PS). The interchangeability of cut-off values was examined by assessing agreement between BF, BV, and PS measured with different mathematical-kinetic methods.

Results Bland-Altman analysis demonstrated poor agreement between perfusion parameters, measured with different mathematical-kinetic methods. According to receiver operating characteristic (ROC) analysis, PS measured with the Patlak method had the significantly lowest diagnostic accuracy (area under ROC curve = 0.748). All other parameters were of high diagnostic accuracy (area under ROC curve = 0.940–0.997), although differences in diagnostic accuracy were not statistically different. Cut-off values for BF of ≤ 91.83 ml/100 ml/min and for BV of ≤ 5.36 ml/100 ml, both measured with the deconvolution method, appear to be the most appropriate cut-off values to distinguish pancreatic adenocarcinoma from normal tissue.

Conclusion Perfusion parameters obtained by different methods are not interchangeable. Therefore, cut-off values, which were determined using different methods, are not interchangeable either. Perfusion parameters can help to distinguish pancreatic adenocarcinoma from normal tissue with high diagnostic accuracy, except for PS measured with the Patlak method.

Key Points: 

• Perfusion CT parameters showed high diagnostic accuracy in differentiating between pancreatic adenocarcinoma and normal tissue.

• Only PS measured with the Patlak method showed a significantly lower diagnostic accuracy.

• Perfusion parameters measured with different mathematical-kinetic methods are not interchangeable.

• A specific cut-off value must be determined for each method and each perfusion parameter.

Citation Format

• Koell M, Klauss M, Skornitzke S et al. Computed Tomography Perfusion Analysis of Pancreatic Adenocarcinoma with the Deconvolution, Maximum Slope, and Patlak Methods – Evaluation of Diagnostic Accuracy and Interchangeability of Cut-Off Values. Fortschr Röntgenstr 2021; 193: 1062 – 1073

Zusammenfassung

Ziel Ziel dieser Studie war es, die diagnostische Güte von Perfusions-Computertomografie (CT) -Parametern zu evaluieren, die mit verschiedenen mathematisch-kinetischen Methoden gemessen wurden, für die Differenzierung zwischen Pankreaskarzinom und Normalgewebe. Es sollten zudem Cut-off-Werte bestimmt und die Austauschbarkeit von Cut-off-Werten, die mit verschiedenen Methoden ermittelt wurden, evaluiert werden.

Material und Methoden Bei 23 Patienten wurde prospektiv eine Perfusions-CT-Bildgebung des Pankreas durchgeführt. 19 Patienten mit histopathologisch bestätigtem Pankreaskarzinom wurden in die Studie eingeschlossen. Der Blutfluss (BF), das Blutvolumen (BV) und das Permeabilitätsoberflächenprodukt (PS) wurden im Pankreaskarzinom und Normalgewebe mit der Deconvolution- (BF, BV, PS), Maximum-Slope- (BF) und Patlak-Methode (BV, PS) gemessen. Die Austauschbarkeit der Cut-off-Werte wurde evaluiert, indem die Übereinstimmung zwischen BF, BV und PS untersucht wurde, die mit verschiedenen mathematisch-kinetischen Methoden gemessen wurden.

Ergebnisse Die Bland-Altman-Analyse zeigte eine schlechte Übereinstimmung zwischen den Perfusionsparametern, die mit verschiedenen mathematisch-kinetischen Methoden gemessen wurden. Gemäß ROC-Analyse (Receiver Operating Characteristic) hatte das mit der Patlak-Methode gemessene PS die signifikant niedrigste diagnostische Güte (Fläche unter der ROC-Kurve = 0,748). Alle anderen Parameter hatten eine hohe diagnostische Güte (Fläche unter der ROC-Kurve = 0,940–0,997); deren diagnostische Güte unterschied sich jedoch nicht statistisch signifikant. Cut-off-Werte für BF von ≤ 91,83 ml/100 ml/min und für BV von ≤ 5,36 ml/100 ml, beide mit der Deconvolution-Methode gemessen, scheinen die geeignetsten Cut-off-Werte zu sein, mit denen das Pankreaskarzinom von Normalgewebe abgegrenzt werden kann.

Schlussfolgerung Perfusionsparameter, die mit verschiedenen Methoden gemessen wurden, sind nicht austauschbar. Daraus folgt, dass Cut-off-Werte, die mit unterschiedlichen Methoden ermittelt wurden, ebenfalls nicht austauschbar sind. Perfusionsparameter können dazu beitragen, das Pankreaskarzinom mit hoher diagnostischer Güte vom Normalgewebe abzugrenzen, mit Ausnahme von PS, das mit der Patlak-Methode gemessen wurde.

Kernaussagen: 

• Perfusions-CT-Parameter zeigten eine hohe diagnostische Güte bei der Differenzierung zwischen Pankreaskarzinom und Normalgewebe.

• Nur PS, gemessen mit der Patlak-Methode, zeigte eine signifikant niedrigere diagnostische Güte.

• Perfusionsparameter, die mit unterschiedlichen mathematisch-kinetischen Methoden gemessen wurden, sind nicht austauschbar.

• Für jede Methode und jeden Perfusionsparameter muss ein spezifischer Cut-off-Wert bestimmt werden.

Key words

CT - pancreas - adenocarcinoma - abdomen

Publikationsverlauf

Eingereicht: 14. Januar 2021

Angenommen: 13. Februar 2021

Artikel online veröffentlicht:
26. März 2021

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