The validity and reliability of computed tomography orbital volume measurements

Silviu C. Diaconu, David Dreizin, Mehmet Uluer, Corey Mossop, Michael Grant, Arthur J. Nam

Research output: Contribution to journalArticle

Abstract

Purpose: Orbital volume calculations allow surgeons to design patient-specific implants to correct volume deficits. It is estimated that changes as small as 1 ml in orbital volume can lead to enophthalmos. Awareness of the limitations of orbital volume computed tomography (CT) measurements is critical to differentiate between true volume differences and measurement error. The aim of this study is to analyze the validity and reliability of CT orbital volume measurements. Materials and methods: A total of 12 cadaver orbits were scanned using a standard CT maxillofacial protocol. Each orbit was dissected to isolate the extraocular muscles, fatty tissue, and globe. The empty bony orbital cavity was then filled with sculpting clay. The volumes of the muscle, fat, globe, and clay (i.e., bony orbital cavity) were then individually measured via water displacement. The CT-derived volumes, measured by manual segmentation, were compared to the direct measurements to determine validity. Results and conclusions: The difference between CT orbital volume measurements and physically measured volumes is not negligible. Globe volumes have the highest agreement with 95% of differences between -0.5 and 0.5 ml, bony volumes are more likely to be overestimated with 95% of differences between -1.8 and 2.6 ml, whereas extraocular muscle volumes have poor validity and should be interpreted with caution.

Original languageEnglish (US)
JournalJournal of Cranio-Maxillofacial Surgery
DOIs
StateAccepted/In press - 2017
Externally publishedYes

Fingerprint

Cone-Beam Computed Tomography
Reproducibility of Results
Oculomotor Muscles
Orbit
Enophthalmos
Muscles
Cadaver
Adipose Tissue
Fats
Tomography
Water
clay

Keywords

  • Accuracy
  • CT
  • Enophthalmos
  • Orbit
  • Volume

ASJC Scopus subject areas

  • Surgery
  • Oral Surgery
  • Otorhinolaryngology

Cite this

The validity and reliability of computed tomography orbital volume measurements. / Diaconu, Silviu C.; Dreizin, David; Uluer, Mehmet; Mossop, Corey; Grant, Michael; Nam, Arthur J.

In: Journal of Cranio-Maxillofacial Surgery, 2017.

Research output: Contribution to journalArticle

Diaconu, Silviu C. ; Dreizin, David ; Uluer, Mehmet ; Mossop, Corey ; Grant, Michael ; Nam, Arthur J. / The validity and reliability of computed tomography orbital volume measurements. In: Journal of Cranio-Maxillofacial Surgery. 2017.
@article{fc085a96d5c64eca97ca9e38836e3784,
title = "The validity and reliability of computed tomography orbital volume measurements",
abstract = "Purpose: Orbital volume calculations allow surgeons to design patient-specific implants to correct volume deficits. It is estimated that changes as small as 1 ml in orbital volume can lead to enophthalmos. Awareness of the limitations of orbital volume computed tomography (CT) measurements is critical to differentiate between true volume differences and measurement error. The aim of this study is to analyze the validity and reliability of CT orbital volume measurements. Materials and methods: A total of 12 cadaver orbits were scanned using a standard CT maxillofacial protocol. Each orbit was dissected to isolate the extraocular muscles, fatty tissue, and globe. The empty bony orbital cavity was then filled with sculpting clay. The volumes of the muscle, fat, globe, and clay (i.e., bony orbital cavity) were then individually measured via water displacement. The CT-derived volumes, measured by manual segmentation, were compared to the direct measurements to determine validity. Results and conclusions: The difference between CT orbital volume measurements and physically measured volumes is not negligible. Globe volumes have the highest agreement with 95{\%} of differences between -0.5 and 0.5 ml, bony volumes are more likely to be overestimated with 95{\%} of differences between -1.8 and 2.6 ml, whereas extraocular muscle volumes have poor validity and should be interpreted with caution.",
keywords = "Accuracy, CT, Enophthalmos, Orbit, Volume",
author = "Diaconu, {Silviu C.} and David Dreizin and Mehmet Uluer and Corey Mossop and Michael Grant and Nam, {Arthur J.}",
year = "2017",
doi = "10.1016/j.jcms.2017.06.024",
language = "English (US)",
journal = "Journal of Cranio-Maxillo-Facial Surgery",
issn = "1010-5182",
publisher = "Churchill Livingstone",

}

TY - JOUR

T1 - The validity and reliability of computed tomography orbital volume measurements

AU - Diaconu, Silviu C.

AU - Dreizin, David

AU - Uluer, Mehmet

AU - Mossop, Corey

AU - Grant, Michael

AU - Nam, Arthur J.

PY - 2017

Y1 - 2017

N2 - Purpose: Orbital volume calculations allow surgeons to design patient-specific implants to correct volume deficits. It is estimated that changes as small as 1 ml in orbital volume can lead to enophthalmos. Awareness of the limitations of orbital volume computed tomography (CT) measurements is critical to differentiate between true volume differences and measurement error. The aim of this study is to analyze the validity and reliability of CT orbital volume measurements. Materials and methods: A total of 12 cadaver orbits were scanned using a standard CT maxillofacial protocol. Each orbit was dissected to isolate the extraocular muscles, fatty tissue, and globe. The empty bony orbital cavity was then filled with sculpting clay. The volumes of the muscle, fat, globe, and clay (i.e., bony orbital cavity) were then individually measured via water displacement. The CT-derived volumes, measured by manual segmentation, were compared to the direct measurements to determine validity. Results and conclusions: The difference between CT orbital volume measurements and physically measured volumes is not negligible. Globe volumes have the highest agreement with 95% of differences between -0.5 and 0.5 ml, bony volumes are more likely to be overestimated with 95% of differences between -1.8 and 2.6 ml, whereas extraocular muscle volumes have poor validity and should be interpreted with caution.

AB - Purpose: Orbital volume calculations allow surgeons to design patient-specific implants to correct volume deficits. It is estimated that changes as small as 1 ml in orbital volume can lead to enophthalmos. Awareness of the limitations of orbital volume computed tomography (CT) measurements is critical to differentiate between true volume differences and measurement error. The aim of this study is to analyze the validity and reliability of CT orbital volume measurements. Materials and methods: A total of 12 cadaver orbits were scanned using a standard CT maxillofacial protocol. Each orbit was dissected to isolate the extraocular muscles, fatty tissue, and globe. The empty bony orbital cavity was then filled with sculpting clay. The volumes of the muscle, fat, globe, and clay (i.e., bony orbital cavity) were then individually measured via water displacement. The CT-derived volumes, measured by manual segmentation, were compared to the direct measurements to determine validity. Results and conclusions: The difference between CT orbital volume measurements and physically measured volumes is not negligible. Globe volumes have the highest agreement with 95% of differences between -0.5 and 0.5 ml, bony volumes are more likely to be overestimated with 95% of differences between -1.8 and 2.6 ml, whereas extraocular muscle volumes have poor validity and should be interpreted with caution.

KW - Accuracy

KW - CT

KW - Enophthalmos

KW - Orbit

KW - Volume

UR - http://www.scopus.com/inward/record.url?scp=85025176048&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85025176048&partnerID=8YFLogxK

U2 - 10.1016/j.jcms.2017.06.024

DO - 10.1016/j.jcms.2017.06.024

M3 - Article

C2 - 28747263

AN - SCOPUS:85025176048

JO - Journal of Cranio-Maxillo-Facial Surgery

JF - Journal of Cranio-Maxillo-Facial Surgery

SN - 1010-5182

ER -