Strain Elastography for Prediction of Malignancy in Soft Tissue Tumours – Preliminary Results

Abstract

Purpose: To evaluate the ability of strain elastography to predict malignancy in patients with soft tissue tumors, and to compare three evaluation methods of strain elastography: strain ratios, strain histograms and visual scoring.

Materials and Methods: 60 patients with 61 tumors were analyzed in the study. All patients were referred due to suspicion of malignant soft tissue tumors after diagnostic imaging (contrast-enhanced MRI, CT or PET-CT). Ultrasound-guided biopsy was preceded by the recording of strain elastography video clips, which were evaluated in consensus between three investigators. Strain ratio, strain histogram analysis and visual scoring using a five-point visual scale were compared with the final pathology from either biopsy or resection of the tumors.

Results: The difference between the mean strain ratio for malignant and benign tumors was significant (p = 0.043). The mean strain ratios for malignant and benign tumors were 1.94 (95 % CI [0.37; 10.21]) and 1.35 (95 % CI [0.32; 5.63]), respectively. There were no significant differences for strain histograms or visual scoring. Liposarcomas had lower mean strain ratio, strain histogram values, and visual scoring than other malignant tumors. When analyzing a subgroup of patients without fat-containing tumors (n = 46), based on appearance on MRI or CT, the difference between the mean strain ratios for malignant and benign tumors increased (p = 0.014).

Conclusion: The mean strain ratios of malignant tumors were significantly higher than the mean strain ratios of benign tumors. There was no significant difference for strain histograms and visual scoring. Strain ratios may be used as an adjunct in soft tissue tumor diagnosis, possibly minimizing the number of biopsies.

Zusammenfassung

Ziel: Bewertung, ob die Strain-Elastografie in der Lage ist, Malignität bei Patienten mit Weichteiltumoren vorherzusagen, sowie Vergleich von drei Auswertungsmethoden der Strain-Elastografie: Strain-Ratios, Strain-Histogramme und die visuelle Bewertung.

Material und Methoden: In der Studie wurden 60 Patienten mit 61 Tumoren analysiert. Alle Patienten wurden wegen Verdachts auf bösartige Weichteiltumore nach bildgebender Diagnostik (kontrastverstärktes MRT, CT oder PET-CT) aufgenommen. Eine ultraschall-gestützte Biopsie ging der Aufnahme der Strain-Elastografie Video-Clips voran, die von drei Untersuchern im Konsensus ausgewertet wurden. Die Strain-Ratio, die Analyse des Strain-Histogramms und die visuelle Bewertung mittels einer 5-Punkte visuellen Skala wurden mit dem pathologischen Endbefund der Biopsie oder des entfernten Tumors verglichen.

Ergebnisse: Der Unterschied zwischen mittlerer Strain-Ratio von gutartigen und malignen Tumoren war statistisch signifikant (p = 0,043). Die mittlere Strain-Ratio für maligne Tumoren betrug 1,94 (95 % CI [0,37; 10,21]) und die entsprechende für gutartige Tumoren war 1,35 (95 % CI [0,32; 5,63]). Es gab keine signifikanten Unterschiede zwischen Strain-Histogrammen und visueller Bewertung. Liposarkome hatten niedrigere mittlere Werte für Strain-Ratios, Strain-Histogramme und visuelle Bewertungen als andere maligne Tumoren. Wenn man jedoch eine Untergruppe an Patienten analysierte, deren Tumoren aufgrund des Befundes im MRT oder CT kein Fett beinhaltete (n = 46), so war die Differenz der mittleren Strain-Ratios zwischen malignen und benignen Tumoren erhöht (p = 0,014).

Schlussfolgerung: Die mittleren Strain-Ratios von malignen Tumoren waren signifikant höher als diejenigen der gutartigen Tumoren. Es gab keinen signifikanten Unterschied zwischen Strain-Histogrammen und visueller Bewertung. Die Strain-Ratios können als zusätzlicher Marker bei der Diagnostik von Weichteiltumoren dienen und möglicherweise die Zahl der Biopsien reduzieren.

Key words

strain elastography - soft tissue tumors - sarcoma - ultrasound - musculoskeletal tissue

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