Estimating voxel volume fractions of trabecular bone on the basis of magnetic resonance images acquiredin vivo

Hwang, Scott N.; Wehrli, Félix W.

doi:10.1002/(sici)1098-1098(1999)10:2<186::aid-ima9>3.0.co;2-7

Cited by 50 publications

(33 citation statements)

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“…Conventional MRI technology does not satisfy these more stringent requirements. To address the problems associated with the limited spatial resolution regime of in vivo -MRI, image acquisition, restoration, and processing techniques have recently been developed in our laboratory (18,19).Here, we demonstrate the potential of serial combined -MR imaging and spectroscopy for the quantitative assessment of shortterm steroid exposure on trabecular bone, growth plate, and bone marrow composition in a rabbit model. The method, which was implemented on a standard 1.5-Tesla clinical MR scanner by using customized data acquisition and image processing techniques, is shown to provide detailed information on trabecular bone architecture and bone marrow changes occurring within a time span of 2 to 4 weeks of dexamethasone exposure.…”

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confidence: 83%

“…The -MRI data from 16-18 slices (28 total, encompassing the epiphysis and excluding distal cortex and growth plate) were processed after manually isolating the trabecular bone area. From these data, the trabecular bone volume fraction TB͞TV (trabecular bone volume͞total volume) was computed pixel by pixel by using a histogram deconvolution algorithm, which removes image intensity nonuniformity and noise (19). The resulting images are maps of TB͞TV in which the gray value represents the fractional occupancy of bone.…”

Section: Methodsmentioning

confidence: 96%

mentioning

confidence: 99%

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In vivo NMR microscopy allows short-term serial assessment of multiple skeletal implications of corticosteroid exposure

Takahashi¹,

Wehrli²,

Hilaire³

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

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Corticosteroids are in widespread clinical use but are known to have adverse skeletal side effects. Moreover, it is not known how soon these effects become apparent. Here, we describe a longitudinal approach to evaluate the short-term implications of excess corticosteroid exposure by quantitative in vivo magnetic resonance imaging and spectroscopy in conjunction with digital image processing and analysis in a rabbit model. Two-week treatment with dexamethasone induced a significant reduction in trabecular bone volume, which occurred at the expense of uniform trabecular thinning without affecting network architecture. Paralleling the loss in bone volume was conversion of hematopoietic to yellow marrow in the femoral metaphysis and atrophy of the femoral epiphyseal growth plate. This work demonstrates that detailed quantitative morphometric and physiological information can be obtained noninvasively at multiple skeletal locations. The method is likely to eventually replace invasive histomorphometry in that it obviates the need to sacrifice groups of animals at multiple time points. Finally, this work, which was performed on a clinical scanner, has implications for evaluating patients on high-dose steroid treatment.B one loss and concomitant fractures of the vertebrae and hip are common clinical consequences of corticosteroid (CS) treatment for inflammatory conditions (1). The overall incidence of osteopenia induced by treatment with CS for a period of less than 6 months is approximately 50% (2). Further, excess CS causes conversion of hematopoietic to fatty bone marrow (3). Besides bone loss, CS treatment is known to have multiple other skeletal implications and thus represents a major public health problem. Of particular concern are pediatric patients treated with high doses of CS (4, 5). Little, however, is known about the early response to supraphysiologic CS levels on the musculoskeletal system.Clinically, fracture risk is most commonly assessed on the basis of bone mineral density (BMD) measured with dual-energy x-ray bone absorptiometry (DEXA) or peripheral quantitative computed tomography (p-QCT). However, it is well known that BMD is not the sole determinant of bone strength and that architecture plays a significant role in conferring strength to the trabecular network (6-8). Unlike bone mineral densitometry, which affords a measure of global or regional bone density, we and others have shown that magnetic resonance microimaging ( -MRI) can quantify trabecular bone microarchitecture in vitro in specimens and biopsies (9-13) and in vivo in laboratory animals and humans (14-16). Whereas microcomputed tomography ( -CT) can generate high-resolution images of trabecular bone architecture (17), magnetic resonance (MR) is unique in that it is also able to provide detailed information on structure and function of soft tissues and bone marrow, which are also affected by steroid treatment.One of the difficulties of imaging microarchitecture in vivo is achievement of sufficient resolution and signal-to-noise ratio to...

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confidence: 83%

Section: Methodsmentioning

confidence: 96%

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In vivo NMR microscopy allows short-term serial assessment of multiple skeletal implications of corticosteroid exposure

Takahashi¹,

Wehrli²,

Hilaire³

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

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“…Hwang et al developed a histogram deconvolution algorithm (HDA), that seeks to generate a grayscale image in which the pixel intensity represents the fractional occupancy of bone, i.e. a bone volume fraction (BVF) image that is free of noise and intensity anomalies as they arise from spatial variations in the received signal (106). Such an approach obviates the need for threshold setting and has the advantage that the full information is retained (rather than resulting in the data reduction inherent to all thresholding techniques).…”

Section: Processing Of Trabecular Bone Imagesmentioning

confidence: 99%

“…Subsequently, the error is subtracted from the initial estimate and the process repeated until the error has fallen below a predetermined threshold. Finally, the histogram intensities are assigned to the image pixels on the basis of the probability of a pixel to contain bone, and connectivity arguments (106).…”

Section: Processing Of Trabecular Bone Imagesmentioning

confidence: 99%

Quantitative MRI for the assessment of bone structure and function

et al. 2006

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Osteoporosis is the most common degenerative disease in the elderly. It is characterized by low bone mass and structural deterioration of bone tissue, leading to morbidity and increased fracture risk in the hip, spine and wrist-all sites of predominantly trabecular bone. Bone densitometry, currently the standard methodology for diagnosis and treatment monitoring, has significant limitations in that it cannot provide information on the structural manifestations of the disease. Recent advances in imaging, in particular MRI, can now provide detailed insight into the architectural consequences of disease progression and regression in response to treatment. The focus of this review is on the emerging methodology of quantitative MRI for the assessment of structure and function of trabecular bone. During the past 10 years, various approaches have been explored for obtaining image-based quantitative information on trabecular architecture. Indirect methods that do not require resolution on the scale of individual trabeculae and therefore can be practiced at any skeletal location, make use of the induced magnetic fields in the intertrabecular space. These fields, which have their origin in the greater diamagnetism of bone relative to surrounding marrow, can be measured in various ways, most typically in the form of R 0 2 , the recoverable component of the total transverse relaxation rate. Alternatively, the trabecular network can be quantified by high-resolution MRI (m-MRI), which requires resolution adequate to at least partially resolve individual trabeculae. Micro-MRI-based structure analysis is therefore technically demanding in terms of image acquisition and algorithms needed to extract the structural information under conditions of limited signal-to-noise ratio and resolution. Other requirements that must be met include motion correction and image registration, both critical for achieving the reproducibility needed in repeat studies. Key clinical applications targeted involve fracture risk prediction and evaluation of the effect of therapeutic intervention.

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Three-dimensional digital topological characterization of cancellous bone architecture

Saha

Gomberg

Wehrli

2000

Int. J. Imaging Syst. Technol.

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110

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Cancellous bone consists of a network of bony struts and plates that provide mechanical strength to much of the skeleton at minimum weight. It has been shown that loss in bone mass is accompanied by architectural changes that relate to both scale and topology of the network. In this paper, the concept of three‐dimensional (3D) digital topology is presented for characterizing the local topology of each bone voxel after skeletonization of the binary bone images. This method allows us to identify each voxel as belonging to a surface, curve, or junction structure in the trabecular bone network. The method has been quantitatively validated on synthetic images demonstrating its relative immunity to partial volume blurring and noise. Parameters introduced to characterize network topology include surface‐to‐curve ratio and erosion index. Finally, the technique is shown to quantify the architecture of human trabecular bone in magnetic resonance micro‐images acquired from cadavers and in vivo.© 2000 John Wiley & Sons, Inc. Int J Imaging Syst Technol, 11, 81–90, 2000

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Estimating voxel volume fractions of trabecular bone on the basis of magnetic resonance images acquiredin vivo

Cited by 50 publications

References 13 publications

In vivo NMR microscopy allows short-term serial assessment of multiple skeletal implications of corticosteroid exposure

In vivo NMR microscopy allows short-term serial assessment of multiple skeletal implications of corticosteroid exposure

Quantitative MRI for the assessment of bone structure and function

Three-dimensional digital topological characterization of cancellous bone architecture

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