Unbiased estimation of human body composition by the Cavalieri method using magnetic resonance imaging

Abstract

Summary The classical methods for estimating the volume of human body compartments in vivo (e.g. skin‐fold thickness for fat, radioisotope counting for different compartments, etc.) are generally indirect and rely on essentially empirical relationships — hence they are biased to unknown degrees. The advent of modern non‐invasive scanning techniques, such as X‐ray computed tomography (CT) and magnetic resonance imaging (MRI) is now widening the scope of volume quantification, especially in combination with stereological methods. Apart from its superior soft tissue contrast, MRI enjoys the distinct advantage of not using ionizing radiations. By a proper landmarking and control of the scanner couch, an adult male volunteer was scanned exhaustively into parallel systematic MR ‘sections’. Four compartments were defined, namely bone, muscle, organs and fat (which included the skin), and their corresponding volumes were easily and efficiently estimated by the Cavalieri method: the total section area of a compartment times the section interval estimates the volume of the compartment without bias. Formulae and nomograms are given to predict the errors and to optimize the design. To estimate an individual's muscle volume with a 5% coefficient of error, 10 sections and less than 10min point counting (to estimate the relevant section areas) are required. Bone and fat require about twice as much work. To estimate the mean muscle volume of a population with the same error contribution, from a random sample of six subjects, the workload per subject can be divided by √6, namely 4 min per subject. For a given number of sections planimetry would be as accurate but far more time consuming than point counting.

The fascicular anatomy and peak force capabilities of the sternocleidomastoid muscle

“…This study promotes the use of the Cavalieri method to calculate muscle volumes from MRI slices. As has been previously reported, this method is efficient, unbiased and accurate [23], and well suited to muscle volume calculations [10].…”

“…The physiological cross-sectional area (PCSA) for each portion were calculated using Muscle volumes were calculated using the Cavalieri method, which is a wellestablished stereological method for calculating volumes from slices, that is both efficient and accurate [23]. This involved systematic sampling of slices from a random starting point.…”

“…Our calculations were based on ~10 slices along the length of the muscle in line with recommendations of Roberts et al [23]. Whole muscle cross-sectional muscle areas were traced in the sampled slices using OsiriX software (a freely available DICOM viewer), after which the volume of the muscle could be estimated.…”

Observation of intramyocellular lipids by means of1H magnetic resonance spectroscopy

“…This procedure can be used to evaluate the involvement of muscles during exercise in ergometers in the MR magnet. MRI can also be used for the determination of body composition and muscle volumes (Fukunaga et al 1992;LeBlanc et al 1992;McColl et al 1992;Narici et al 1992;Roberts et al 1993;Elliott et al 1997;Fusch et al 1998;Kamber et al 1999). The application of MRI to the study of the physiology of skeletal muscle has been the subject of many review articles (Bassett & Gold, 1989;Fleckenstein et al 1991;Brown & Bradley, 1994;Herzog, 1994;Sonin, 1994;Terk & Kwong, 1994;Basser, 1995;Conley et al 1995;Heymsfield et al 1995;McCully & Posner, 1995;Cooper & Barstow, 1996;Kneeland, 1997;Tung & Brody, 1997;Walker & Moore, 1997;.…”

Do longus capitis and colli really stabilise the cervical spine? A study of their fascicular anatomy and peak force capabilities

“…The main images were three blocks of axial T1-weighted scans; each 32 slices, 3 mm thick with 0 mm gap, field of view 410mm, TR 500ms, TE 13ms, matrix 480 x 512, 4 number of signals averaged (NSA). Muscle volumes were calculated using the Cavalieri method, a wellestablished stereological method for calculating volumes from slices (Roberts et al, 1993).…”