Semi-automatic magnetic resonance imaging based orbital fat volumetry: reliability and correlation with computed tomography

Abstract

Post-processing analysis can provide valuable information for diagnosis and planning of orbital disorders. This cross-sectional study aims to evaluate the reliability of semi-automatic, orbital fat volumetry using magnetic resonance imaging (MRI). Two observers assessed the orbital fat volume using a standard MRI protocol (3T, T1w sequence) in 12 orbits diagnosed with Graves' orbitopathy (GO) and 10 healthy control orbits. MRI and computed tomography (CT) based analysis were compared. Intra-observer variability was good (intraclass correlation coefficient (ICC) 0.88; 95% confidence interval (CI) [0.70, 0.95]) and interobserver agreement was moderate (ICC 0.55; 95% CI [À0.09, 0.81]), which corresponds to a mean percentage difference of 1.3% and 17.9% of the total orbital fat volume. Mean differences between MRI and CT measurements were, respectively, 1.1 cm 3 (P= 0.064, 95% CI [À0.20, 2.43]) and 1.4 cm 3 (P=0.016, 95% CI [0.21, 2.56]) for the control and the GO group. MRI volumetry was strongly correlated with CT (Pearson's r= 0.7, P<0.001). We conclude that orbital fat volumetry is feasible with a semi-automatic segmentation procedure and standard MRI protocol. Correlation with CT volumetry is good, but considerable bias may derive from observer variability and these errors should be taken into account for the purpose of volumetric analysis. Better definition of error sources may increase measurement accuracy.

Increased Orbital Muscle Fraction Diagnosed by Semi-Automatic Volumetry: A Risk Factor for Severe Visual Impairment with Excellent Response to Surgical Decompression in Graves’ Orbitopathy

“…Although MRI is also used for imaging diagnostics today, CT continues to be frequently used as the preferred technique since both the bony orbit and intraorbital structures are excellently visualized [ 1 , 6 , 17 ]. Volumetric analysis of (intra-)orbital structures has been established on the basis of both CT and MR images with comparable results [ 8 , 14 , 18 , 19 , 20 ]. In addition to fully manual segmentation (planimetry), the semi-automatic technique (with the possibility of manual adjustment) has also proven successful for volumetric analysis [ 21 , 22 ].…”

Automatic Segmentation of Teeth, Crown–Bridge Restorations, Dental Implants, Restorative Fillings, Dental Caries, Residual Roots, and Root Canal Fillings on Orthopantomographs: Convenience and Pitfalls

“…AI will come to be increasingly preferred in the fields of medicine and dentistry due to its important contributions to patient health services and the convenience that it provides to practicians. The increase in processing speed, computing power, storage capacity, ability to perform different tasks, and the affordability of advanced graphics processing units as well as computers are considered the beginning of a new era in medicine and especially in radiology [ 1 , 2 , 3 ].…”

Application of Multiparameter Quantitative Magnetic Resonance Imaging in the Evaluation of Graves' Ophthalmopathy

“…7 In recent years, studies have been performed using orbital MRI to quantitatively analyze GO patients. [8][9][10][11][12][13] Currently, the most commonly used imaging sequences are short-tau inversion recovery (STIR), 7,10,11,13 T2 mapping, 8,9 and diffusion-weighted imaging (DWI). [14][15][16] Orbital MRI has enabled accurate quantification and can reflect the inflammation, steatosis, fibrosis and other pathological changes of GO.…”

“…[14][15][16] Orbital MRI has enabled accurate quantification and can reflect the inflammation, steatosis, fibrosis and other pathological changes of GO. 7,8,[10][11][12] The microstructural changes of the ocular soft tissue can be detected earlier and more accurately and can be monitored over time. 17,18 Calculation of orbital soft tissue volume using 3D reconstruction of MRI data 19 has been shown to be both reliable and accurate, but the relationships between imaging parameters and GO disease activity and severity have not been fully explored.…”

“…Compared with CT or ultrasound, magnetic resonance imaging (MRI) has important advantages such as nonionizing radiation, high inherent soft tissue contrast, better reflection of tissue water content, and the ability to quantify multiple parameters 7 . In recent years, studies have been performed using orbital MRI to quantitatively analyze GO patients 8–13 . Currently, the most commonly used imaging sequences are short‐tau inversion recovery (STIR), 7,10,11,13 T2 mapping, 8,9 and diffusion‐weighted imaging (DWI) 14–16 .…”