Article
The natural history of sporadic vestibular schwannomas – correlation of tumour volume to growth rate, occurrence of a cystic component and its respective volume
Das natürliche Wachstumsverhalten von Vestibularisschwannomen – Korrelation zwischen Tumorvolumen und Wachstumsrate, Auftreten einer zytischen Komponente und Zystenvolumen
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Published: | May 8, 2019 |
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Objective: To analyze the size of sporadic vestibular schwannoma (VS) based on volumetric measurements in correlation to growth rate, occurrence of a cystic component and its respective volume.
Methods: We retrospectively assessed the tumor volumetry of patients with a sporadic vestibular schwannoma initially observed (watch and wait) and then when indicated operated between January 2004 and May 2018 in our Department. We included those patients with a minimum MRI follow-up of 6 months before any treatment documented in our picture archiving and communication system (PACS). VS were grouped according to the Hannover classification.
The tumor volumetry was performed on T1-weighted images with gadolinum using the iplan 7 (brainlab®). The VS (and their cystic components in case of cystic VS) were contoured on each slice manually to calculate the volume and the growth rate.
Results: In 287 patients MRI-scans with a temporal distance of more than 6 months before any treatment were filed in the PACS. 170 patients were operated (group A), 117 are still observed (group B).
Group A: The mean volume of the T1 VS in the group of operated patients (group A) was 0,190 cm³, with a mean growth rate per year of 0,068 cm³ (occurrence of cystic portion 0%).
The mean volumes and mean growth rates of the T2, T3 and T4 VS in group B were 0,559cm3 with a growth rate of 0,253 cm3 per year (occurrence of cystic potion 0,09 %), 2,516 cm3 with a growth rate of 1,015 cm3 per year (occurrence of cystic portion 11,8%) and 10,421 cm3 with a growth rate of 3,603 cm3 per year (occurrence of cystic portion 24.07%).
Group B: The mean volume of the T1 VS in the group of patients who are still followed with a watch-and-wait policy was 0,154 cm3 with a mean growth rate per year of 0,07 cm3. The mean volumes of the T2, T3 and T4 VS in this group were 0,548 cm3, 1,581 cm3 and 12.103 cm3. Growth rate, occurrence of a cystic portion and volume of the cystic portion also increased in this group with rising tumor grade.
Conclusion: Through volumetric analysis, the current study revealed that the tumor volumes of the vestibular schwannomas correlated to growth rate, occurence of cystic components and size of the cystic portions.