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Eur Arch Otorhinolaryngol. 2018 Apr;275(4):867-874. doi: 10.1007/s00405-018-4865-z. Epub 2018 Jan 15.

A comparison of semi-automated volumetric vs linear measurement of small vestibular schwannomas.

Author information

1
Cambridge Skull Base Unit, Department of ENT, Addenbrookes Hospital, Cambridge University Hospitals, Cambridge, CB2 0QQ, UK. samuelmackeith@doctors.org.uk.
2
Department of Neuroradiology, Addenbrookes Hospital, Cambridge, UK.
3
Department of Radiology, Addenbrookes Hospital, Cambridge, UK.
4
Cambridge Skull Base Unit, Department of ENT, Addenbrookes Hospital, Cambridge University Hospitals, Cambridge, CB2 0QQ, UK.
5
Department of Neurosurgery, Addenbrookes Hospital, Cambridge, UK.

Abstract

OBJECTIVE:

Accurate and precise measurement of vestibular schwannoma (VS) size is key to clinical management decisions. Linear measurements are used in routine clinical practice but are prone to measurement error. This study aims to compare a semi-automated volume segmentation tool against standard linear method for measuring small VS. This study also examines whether oblique tumour orientation can contribute to linear measurement error.

STUDY DESIGN:

Experimental comparison of observer agreement using two measurement techniques.

SETTING:

Tertiary skull base unit.

PARTICIPANTS:

Twenty-four patients with unilateral sporadic small (< 15 mm maximum intracranial dimension) VS imaged with 1 mm-thickness T1-weighted Gadolinium enhanced MRI.

MAIN OUTCOME MEASURES:

(1) Intra and inter-observer intraclass correlation coefficients (ICC), repeatability coefficients (RC), and relative smallest detectable difference (%SDD). (2) Mean change in maximum linear dimension following reformatting to correct for oblique orientation of VS.

RESULTS:

Intra-observer ICC was higher for semi-automated volumetric when compared with linear measurements, 0.998 (95% CI 0.994-0.999) vs 0.936 (95% CI 0.856-0.972), p < 0.0001. Inter-observer ICC was also higher for volumetric vs linear measurements, 0.989 (95% CI 0.975-0.995) vs 0.946 (95% CI 0.880-0.976), p = 0.0045. The intra-observer %SDD was similar for volumetric and linear measurements, 9.9% vs 11.8%. However, the inter-observer %SDD was greater for volumetric than linear measurements, 20.1% vs 10.6%. Following oblique reformatting to correct tumour angulation, the mean increase in size was 1.14 mm (p = 0.04).

CONCLUSION:

Semi-automated volumetric measurements are more repeatable than linear measurements when measuring small VS and should be considered for use in clinical practice. Oblique orientation of VS may contribute to linear measurement error.

KEYWORDS:

Acoustic neuroma; Measurement; Semi-automated; Vestibular schwannoma; Volumetric

PMID:
29335780
PMCID:
PMC5838150
DOI:
10.1007/s00405-018-4865-z
[Indexed for MEDLINE]
Free PMC Article

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