Color Fusion of Magnetic Resonance Images Improves Intracranial Volume Measurement in Studies of Aging

Abstract

Background:Comparison of intracranial volume (ICV) measurements in different subpopulations offers insight into age-related atrophic change and pathological loss of neuronal tissue. For such comparisons to be meaningful the accuracy of ICV measurement is paramount. Color magnetic resonance images (MRI) have been utilised in several research applications and are reported to show promise in the clinical arena. Methods: We selected a sample of 150 older community-dwelling individuals (age 71 to 72 years) representing a wide range of ICV, white matter lesions and atrophy. We compared the extraction of ICV by thresholding on T2*-weighted MR images followed by manual editing (reference standard) done by an analyst trained in brain anatomy, with thresholding plus computational morphological operations followed by manual editing on a framework of a color fusion technique (MCMxxxVI) and two automatic brain segmentation methods widely used, these last three done by two image analysts. Results: The range of ICV was 1074 to 1921 cm 3 for the reference standard. The mean difference between the reference standard and the ICV measured using the technique that involved the color fusion was 2.7%, while it was 5.4% compared with any fully automatic technique. However, the 95% confidence interval of the difference between the reference standard and each method was similar: it was 7% for the segmentation aided by the color fusion and was 7% and 8.3% for the two fully automatic methods tested. Conclusion: For studies of aging, the use of color fusion MRI in ICV segmentation in a semi-automatic framework delivered best results compared with a reference standard manual method. Fully automated methods, while fast, all require manual editing to avoid significant errors and, in this post-processing step color fusion MRI is recommended.

Rationale, design and methodology of the image analysis protocol for studies of patients with cerebral small vessel disease and mild stroke

“…; Valdes Hernandez et al. , ,b,c). On a sample of 150 individuals aged 71–72 years, the mean difference between a reference standard manually outlined by an experienced analyst and the measurements of ICV performed with the method described in this protocol was 2.7% (95% CI ±7%)(Valdes Hernandez et al.…”

“…The ICV is extracted semiautomatically using the T2*W GRE sequence, with the Object Extraction Tool in Analyze ™ 11.0 followed by manual editing (Valdes Hernandez et al. ). We then use MCMxxxVI (Valdes Hernandez et al.…”

“…We then use MCMxxxVI (Valdes Hernandez et al. ), a multispectral color fusion technique, to identify other intracranial tissues. This technique is implemented in http://www.sourceforge.net/projects/bric1936.…”

“…The measurements obtained computationally from the structural images are described in Table 2, performed separately per scanning session and blind to all other results; with the exception of the intracranial volume (ICV), which is performed only once at baseline and used for all the follow-up analyses. The ICV is extracted semiautomatically using the T2*W GRE sequence, with the Object Extraction Tool in Analyze TM 11.0 followed by manual editing (Valdes Hernandez et al 2012c). We then use MCMxxxVI (Valdes Hernandez et al 2012c), a multispectral color fusion technique, to identify other intracranial tissues.…”

Hippocampal morphology and cognitive functions in community-dwelling older people: the Lothian Birth Cohort 1936

“…First approximations of left and right hippocampal segmentations were obtained from an automated pipeline that uses tools from the FMRIB Software Library version 4.1 (Oxford, UK; http://www.fmrib.ox.ac.uk/fsl/), and an age-relevant template (Farrell et al., 2009), followed by visual inspection and manual correction when required using Analyze 10.0 software (Mayo Clinic, Rochester, MN, USA; www.analyzedirect.com), and saved as binary masks as per previous publications (Aribisala et al., 2014, Wardlaw et al., 2011). Semi-automated measurements of intracranial volume (ICV; contents within the inner skull table including brain tissue, cerebrospinal fluid, veins, and dura; Valdes Hernandez et al., 2012) were used for normalization.…”