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T M Link

Publications and source records attributed to T M Link.

At least 55 records · Page 3Linked to original sources
PubMed2000

Changes in calcaneal trabecular bone structure after heart transplantation: an MR imaging study.

PURPOSE: To use high-spatial-resolution magnetic resonance (MR) imaging to analyze the trabecular bone structure of the calcaneus in patients before and after heart transplantation and to compare this technique with bone mineral density (BMD) measurement in predicting therapy-induced bone loss and vertebral fracture status. MATERIALS AND METHODS: High-spatial-resolution 1.5-T MR imaging of the calcaneus was performed in 40 men 11-120 months after heart transplantation, in 11 men before heart transplantation, and in 10 age-matched male volunteers. Sagittal and transverse T1-weighted spin-echo images with a voxel size of 0.195 x 0.195 x 1.000 mm were obtained, and structure measurements analogous to bone histomorphometric values were calculated. In addition, the BMD of the lumbar spine was determined in the transplant recipients pre- and postoperatively by using quantitative computed tomography, and vertebral fracture status was assessed. RESULTS: Significant differences in structure and BMD measurements were found between patients before and after heart transplantation (P <. 05). In 17 (42%) of 40 transplant recipients, vertebral fractures were found. Although structure measurements were significantly different between patients with and those without fractures (P <.05), BMDs were not. Correlations between time after transplantation and some structure measurements were moderately significant (P <. 05), but such correlations with BMD measurements were not. CONCLUSION: MR imaging-derived structure measurements in the calcaneus are useful for monitoring bone changes after heart transplantation and assessing vertebral fracture status.

Adult↗
PubMed2000

Advanced imaging of the macrostructure and microstructure of bone.

Noninvasive and/or nondestructive techniques are capable of providing more macro- or microstructural information about bone than standard bone densitometry. Although the latter provides important information about osteoporotic fracture risk, numerous studies indicate that bone strength is only partially explained by bone mineral density. Quantitative assessment of macro- and microstructural features may improve our ability to estimate bone strength. The methods available for quantitatively assessing macrostructure include (besides conventional radiographs) quantitative computed tomography (QCT) and volumetric quantitative computed tomography (vQCT). Methods for assessing microstructure of trabecular bone noninvasively and/or nondestructively include high-resolution computed tomography (hrCT), micro-computed tomography (muCT), high-resolution magnetic resonance (hrMR), and micromagnetic resonance (muMR). vQCT, hrCT and hrMR are generally applicable in vivo; muCT and muMR are principally applicable in vitro. Although considerable progress has been made in the noninvasive and/or nondestructive imaging of the macro- and microstructure of bone, considerable challenges and dilemmas remain. From a technical perspective, the balance between spatial resolution versus sampling size, or between signal-to-noise versus radiation dose or acquisition time, needs further consideration, as do the trade-offs between the complexity and expense of equipment and the availability and accessibility of the methods. The relative merits of in vitro imaging and its ultrahigh resolution but invasiveness versus those of in vivo imaging and its modest resolution but noninvasiveness also deserve careful attention. From a clinical perspective, the challenges for bone imaging include balancing the relative advantages of simple bone densitometry against the more complex architectural features of bone or, similarly, the deeper research requirements against the broader clinical needs. The considerable potential biological differences between the peripheral appendicular skeleton and the central axial skeleton have to be addressed further. Finally, the relative merits of these sophisticated imaging techniques have to be weighed with respect to their applications as diagnostic procedures requiring high accuracy or reliability on one hand and their monitoring applications requiring high precision or reproducibility on the other.

Animals↗
PubMed1999

Monitoring radiation-induced changes in bone marrow histopathology with ultra-small superparamagnetic iron oxide (USPIO)-enhanced MRI.

The purpose of this study was to monitor radiation-induced alterations of the blood-bone marrow barrier (BMB) and the reticuloendothelial system (RES) with AMI-227-enhanced magnetic resonance imaging (MRI). Twenty New Zealand white rabbits (n = 10 following total body irradiation and n = 10 controls) underwent AMI-227-enhanced MRI. Pulse sequences included dynamic fast low-angle shot (FLASH; TR/TE 50/4 msec, flip angle 60 degrees) MRI and static T1- and T2-weighted spin-echo (SE) and turbo-SE sequences of the lumbar spine and sacrum. Bone marrow enhancement was quantified as delta signal intensity (SI) (%) =|[(SIpost - SIpre)/SIpre] x 100%| and compared with histopathology, including iron stains and electron microscopy. Dynamic bone marrow deltaSI (%) data steadily increased up to 10-15 minutes after AMI-227 administration, while blood deltaSI (%) data stayed nearly constant, histologically corresponding to iron oxide leakage into the bone marrow interstitium. This bone marrow contrast enhancement increased significantly following irradiation, corresponding to alterations of the endothelial lining of the bone marrow sinusoids. Late postcontrast images exhibited a significant positive T1 enhancement and negative T2 enhancement of the normal bone marrow, which further increased with irradiation due to increased RES activity. Irradiation-induced changes in bone marrow physiology could be reliably assessed with AMI-227-enhanced MRI.

Animals↗
PubMed1999

Trabecular bone architecture in the distal radius using magnetic resonance imaging in subjects with fractures of the proximal femur. Magnetic Resonance Science Center and Osteoporosis and Arthritis Research Group.

To determine whether magnetic resonance (MR)-derived measures of trabecular bone architecture in the distal radius are predictive for prevalent hip fractures, 20 subjects with hip fractures and 19 age-matched postmenopausal controls were studied. Bone mineral density (BMD) measures at the hip (dual-energy X-ray absorptiometry, DXA) and the distal radius (peripheral quantitative computed tomography, pQCT) were also obtained. We compared the MR-based structural measures derived in the radius with those in the calcaneus of the same patients. In the radius, images were acquired at an in-plane resolution of 156 microm and a slice thickness of 0.5 mm. Stereologic measures such as the apparent trabecular thickness (app. Tb.Th), fractional trabecular bone volume (app. BV/TV), trabecular spacing (app. Tb.Sp) and trabecular number (app. Tb.N) were derived from the images. Measures of app. Tb.Sp and app. Tb.N in the distal radius showed significant (p<0.05) differences between the two groups, as did hip BMD measures. However, radial trabecular BMD measures showed only a marginal difference (p = 0.05). Receiver operating curve analysis was used to determine the diagnostic efficacy of BMD, structural measures and a combination of the two. The area under the curve (AUC) for total hip BMD was 0.73, and for radial trabecular BMD was 0.69. AUC for most of the measures of trabecular bone structure at the distal radius was lower than for hip BMD measures; however, AUC for app. Tb.N at the radius was 0.69, comparable to trabecular BMD using pQCT. The AUC for combined BMD (hip) and structure measures was higher (0.87) when radius and calcaneus structure was included. Measures of trabecular architecture derived from MR images combined with BMD measures improve the discrimination between subjects with hip fractures and normal age-matched controls.

Aged↗
PubMed1999

Imaging of trabecular bone structure in osteoporosis.

Osteoporosis is a metabolic bone disorder that is characterized by reduced bone mass and a deterioration of bone structure which results in an increased fracture risk. Since the disease is preventable, diagnostic techniques are of major importance. Standard techniques determine bone mineral density, whereas some of the newer techniques focus on trabecular structure. This article reviews structure analysis techniques in the diagnosis of osteoporosis. Imaging techniques applied to the assessment of trabecular bone structure include conventional radiography, magnification radiography, high-resolution CT (HRCT) and high-resolution MR imaging (HRMRI). The best results were obtained using high-resolution tomographic techniques. The highest spatial resolutions in vivo were achieved using HRMRI. The most common texture analysis techniques that have been used are morphological parameters (analogous to bone histomorphometry). Fractal dimension, co-occurrence matrices, mathematical filter techniques and autocorrelation functions are more complex techniques. Most of the studies evaluating structure analysis show that texture parameters and bone mineral density both predict bone strength and osteoporotic fractures, and that combining both techniques yields the best results in the diagnosis of osteoporosis.

Bone Density↗
PubMed1999

[The texture-analysis of high-resolution computed tomograms as an additional procedure in osteoporosis diagnosis: in-vitro studies on vertebral segments].

PURPOSE: The purpose of this study was to perform texture analysis of high-resolution CT images obtained from human vertebral specimens and to correlate these parameters with the biomechanical stability of the specimens. In addition, structure data were compared with bone mineral density (BMD) assessed by quantitative CT (QCT). MATERIAL AND METHODS: High-resolution CT images and standard QCT sections were obtained in 36 vertebral motion segments, each consisting of two vertebrae with intact ligaments and intervertebral disc. The trabecular structure in the CT images was assessed using three texture analysis techniques: Trabecular threshold area ratio (TTAR), fractal dimension without thresholding (OTS) and fractal dimension with thresholding (ITS). Finally, the maximum compressive strength (MCS) was determined using a biomechanical testing device. RESULTS: A correlation of r = 0.76 (p < 0.01) was obtained for TTAR versus MCS, of r = 0.83 (p < 0.01) for ITS versus MCS, and of r = 0.35 (p > 0.01) for OTS versus MCS, while r = 0.76 (p < 0.01) was found for BMD versus MCS. Best results were obtained by combining structure measures and BMD (r = 0.85, p < 0.01). CONCLUSIONS: This in vitro study showed a significant correlation between structure measures and biomechanical strength, which was comparable to BMD and strength. However, best correlations were obtained by combining both measures. Using both BMD and structure measures therefore may improve the prediction of biomechanically determined bone strength.

Aged↗
PubMed1999

[Primary bone tumors and "tumor-like lesions" of the shoulder. Their histopathology and imaging].

Purpose of this review is to demonstrate typical X-ray, CT and MR morphology of primary bone tumors and "tumor-like lesions" of the shoulder in correlation with histopathology. 711 primary bone tumors of the shoulder and proximal humerus were studied. 602 were localized in the humerus, 90 in the scapula and 19 in the clavicula. The most frequent benign tumors were osteochondromas (n = 143), simple bone cysts (n = 115), enchondromas (n = 75) and aneurysmal bone cysts (n = 50). Fibrous dysplasia (n = 25), chondroblastoma (n = 15), osteoid osteoma (n = 13), giant cell tumors (n = 12) and non ossifying fibroma (n = 11) were less frequent. The most frequent malignant bone tumors were osteosarcoma (n = 72), chondrosarcoma (n = 52) and Ewing's sarcoma (n = 46). Focal plasmocytoma (n = 20) and lymphoma (n = 10) were less frequent. The average age of the patients was 31.5 years. Some of these tumors were typically located in the shoulder, i.e. simple bone cysts and chondroblastoma. In summary the shoulder was a rather infrequent site of primary bone tumors, but since most of these tumors were benign, the radiologist should be aware of the differential diagnosis to guide therapy.

Bone Cysts, Aneurysmal↗
PubMed1998

Ricin A-chain: kinetics, mechanism, and RNA stem-loop inhibitors.

Ricin A-chain (RTA) catalyzes the depurination of a single adenine at position 4324 of 28S rRNA in a N-ribohydrolase reaction. The mechanism and specificity for RTA are examined using RNA stem-loop structures of 10-18 nucleotides which contain the required substrate motif, a GAGA tetraloop. At the optimal pH near 4.0, the preferred substrate is a 14-base stem-loop RNA which is hydrolyzed at 219 min-1 with a kcat/Km of 4.5 x 10(5) M-1 s-1 under conditions of steady-state catalysis. Smaller or larger stem-loop RNAs have lower kcat values, but all have Km values of approximately 5 microM. Both the 10- and 18-base substrates have kcat/Km near 10(4) M-1 s-1. Covalent cross-linking of the stem has a small effect on the kinetic parameters. Stem-loop DNA (10 bases) of the same sequence is also a substrate with a kcat/Km of 0.1 that for RNA. Chemical mechanisms for enzymatic RNA depurination reactions include leaving group activation, stabilization of a ribooxocarbenium transition state, a covalent enzyme-ribosyl intermediate, and ionization of the 2'-hydroxyl. A stem-loop RNA with p-nitrophenyl O-riboside at the depurination site is not a substrate, but binds tightly to the enzyme (Ki = 0.34 microM), consistent with a catalytic mechanism of leaving group activation. The substrate activity of stem-loop DNA eliminates ionization of the 2'-hydroxyl as a mechanism. Incorporation of the C-riboside formycin A at the depurination site provides an increased pKa of the adenine analogue at N7. Binding of this analogue (Ki = 9.4 microM) is weaker than substrate which indicates that the altered pKa at this position is not an important feature of transition state recognition. Stem-loop RNA with phenyliminoribitol at the depurination site increases the affinity substantially (Ki = 0.18 microM). The results are consistent with catalysis occurring by leaving group protonation at ring position(s) other than N7 leading to a ribooxocarbenium ion transition state. Small stem-loop RNAs have been identified with substrate activity within an order of magnitude of that reported for intact ribosomes.

Enzyme Inhibitors↗
PubMed1998

[Computer-assisted structure analysis of trabecular bone in the diagnosis of osteoporosis].

Osteoporosis is characterized by reduced bone mass and a deterioration of bone structure which results in an increased fracture risk. The purpose of this review is to evaluate structure analysis techniques in the diagnosis of osteoporosis. Several imaging techniques were applied to analyze trabecular bone, such as conventional radiography, high-resolution computed tomography (HR-CT) and high-resolution magnetic resonance imaging (HR-MRI). The best results were obtained using high-resolution tomographic techniques. The highest spatial resolutions in vivo were achieved using HR-MRI. These studies show that texture parameters and bone mineral density predict bone strength and osteoporotic fractures in a complementary fashion. Combining both techniques yields the best results in the diagnosis of osteoporosis.

Calcaneus↗
PubMed1998

Power spectral analysis of vertebral trabecular bone structure from radiographs: orientation dependence and correlation with bone mineral density and mechanical properties.

Trabecular bone structure and bone density contribute to the strength of bone and are potentially important in the study of osteoporosis. Fourier transforms of the textural patterns in radiographs of trabecular bone have previously been used for the measurement of trabecular bone structure in subjects, however, the relationship between these measures and biomechanical properties of bone have not previously been established. In this study radiographs were acquired of 28 cubic specimens of spinal trabecular bone along each of the three anatomic axes: cranio-caudal or superior-inferior (SI), medial-lateral (ML), and anterior-posterior (AP). The radiographs were digitized, background corrected, and uniformly aligned. The Fast Fourier transform (FFT) was performed on a region comprised solely of trabecular bone for each image. The zero (DC), first (FMO), and second moments (SMO) of the Fourier power spectrum and the fractal dimension (FD) as determined from the Fourier power spectrum were correlated with stereology measures, with bone mineral density (BMD) as well as with measured biomechanical properties [Young's elastic modulus (YM) and ultimate strength] of the cubes. The results show that the power spectra-based measures, when compared with structural parameters determined using 3D stereology, show good correlations with bone volume fraction, trabecular spacing, thickness, and number. These power spectral measures showed fair to good correlations with BMD and the biomechanical properties. Moreover, the correlations between the power spectral measures of trabecular structure and the BMD, YM, and stereology measures of structure depend on the orientation of the radiographic image. Specifically, these were significant differences in the measured biomechanical properties and the power spectral measures of the trabecular structure between the SI and ML and the SI and AP directions. In addition, depending on the spatial frequency range for analysis, the fractal dimension showed opposite trends with changes in BMD and biomechanical properties. Multivariate regression models showed the correlation coefficients increasing with the inclusion of some of the power spectral measures, suggesting that FFT-based texture analysis may play a potential role in studies of osteoporosis.

Biomechanical Phenomena↗
PubMed1998

Correlation of dynamic contrast-enhanced magnetic resonance imaging with histologic tumor grade: comparison of macromolecular and small-molecular contrast media.

BACKGROUND: The endothelial integrity of microvessels is disrupted in malignant tumors. Quantitative assays of tumor microvascular characteristics based on dynamic magnetic resonance imaging (MRI) were correlated with histopathologic grade in mammary soft tissue tumors. MATERIALS AND METHODS: A spectrum of tumors, benign through highly malignant, was induced in 33 female rats by administration of N -ethyl-N -nitrosourea (ENU), a potent carcinogen. Dynamic contrast-enhanced MRI was performed using a small-molecular contrast medium [gadopentetate, MW = 0.5 kDa] and a macromolecular contrast medium [albumin-(Gd-DTPA)30, MW = 92 kDa] at an interval of 1-2 days. Permeability surface area product (PS), as estimated by the corresponding endothelial transfer coefficient (KPS), and fractional plasma volume (fPV) were calculated for each tumor and each contrast agent using a two-compartment bi-directional kinetic model. MRI microvascular characteristics were correlated with histopathologic tumor grade. RESULTS: Tumor permeability to macromolecular contrast medium, characterized by KPS, showed a highly positive correlation with tumor grade (r 2 = 0.76, P < 10(-10)). KPS values were zero for all benign and some low-grade carcinomas, greater than zero in all other carcinomas, and increased in magnitude with higher tumor grade. A considerably smaller but significantly positive correlation was found between fPV and tumor grade using macromolecular contrast medium (r 2 = 0.25, P < 0.003). No correlation between KPS or fPV values and tumor grade was found using gadopentetate (r 2 = 0.01, P > 0.95 and r2 = 0.03, P > 0.15, respectively). CONCLUSION: Quantitative tumor microvascular permeability assays generated with macromolecular MRI contrast medium correlate closely with histologic tumor grade. No significant correlation is found using small-molecular gadopentetate.

Albumins↗
PubMed1998

Malignant fibrous histiocytoma of bone: conventional X-ray and MR imaging features.

OBJECTIVE: To evaluate the conventional X-ray and MR imaging features of malignant fibrous histiocytoma (MFH) of bone. DESIGN: MRI examinations and conventional radiographs were reviewed in 39 patients with biopsy-proven MFH. Imaging characteristics were analyzed and the differential diagnoses assessed in a masked fashion by two experienced radiologists. RESULTS: Typical X-ray features included aggressive, destructive tumor growth centrally located in the metaphysis of long bones. Periosteal reactions and expansive growth were rarely seen. On MR images extraosseous tumor spread was frequently noted. On T2-weighted images and contrast-enhanced T1-weighted images most of the tumors displayed an inhomogeneous, nodular signal pattern with peripheral Gd-DTPA enhancement. CONCLUSIONS: Although several MR imaging criteria were typical for MFH none of them was specific. X-ray diagnosis of MFH may also prove difficult, with the main differential diagnosis being metastasis in the older and osteosarcoma in the younger population.

Adult↗
PubMed1998

High resolution MRI of small joints: impact of spatial resolution on diagnostic performance and SNR.

This study focuses on the spatial resolution required for cartilage imaging. The purposes of this study were (I) to analyze the diagnostic performance in diagnosing artificially produced cartilage lesions in a small joint model using an optimized fat saturated three-dimensional gradient-echo sequence, (II) to relate the lesion size and depth as diagnosed in the magnetic resonance images with the corresponding pathologic findings and (III) to assess signal-to-noise (SNR) ratios for each of the protocols. Twenty-five artificial cartilage lesions were created in the knee joints of 10 rabbits. These specimens and seven specimens without lesions were imaged at 1.5 T using a three-dimensional gradient-echo sequence with varying slice thickness, field of view and matrix. A total of 404 corresponding images were selected, 50% with and 50% without cartilage lesions. Six radiologists scored all images according to five levels of confidence and receiver operating characteristic (ROC) analysis was performed. Lesion size and depth were compared to the corresponding pathological specimen sections. Additionally SNR ratios were calculated. ROC analysis of pooled data from all readers showed the highest area under the ROC curve for the sequence with the highest spatial resolution, while the diagnostic performance was significantly lower in the other sequences (p <0.01). Assessment of the lesion size and depth was correct in 45% and 40% respectively with the highest resolution and in 29% and 23% with the lowest resolution. SNR ratios decreased with increasing spatial resolution. In conclusion this study shows that increasing spatial resolution improves diagnostic performance in cartilage lesions, though SNR decreases substantially. Assessment of correct lesion size and depth still is limited.

Animals↗
PubMed1998

High-resolution magnetic resonance imaging: three-dimensional trabecular bone architecture and biomechanical properties.

The purpose of this study was to use high-resolution magnetic resonance (MR) imaging combined with image analysis to investigate the three-dimensional (3D) trabecular structure, anisotropy, and connectivity of human vertebral, femoral, and calcaneal specimens. The goal was to determine whether: (a) MR-derived measures depict known skeletal-site-specific differences in architecture and orientation of trabeculae; (b) 3D architectural parameters combined with bone mineral density (BMD) improve the prediction of the elastic modulus using a fabric tensor formulation; (c) MR-derived 3D architectural parameters combined with BMD improve the prediction of strength using a multiple regression model, and whether these results corresponded to the results obtained using higher resolution depictions of trabecular architecture. A total of 94 specimens (12 x 12 x 12 mm cubes) consisting of trabecular bone only were obtained, of which there were 7 from the calcaneus, 15 from distal femur, 47 from the proximal femur, and 25 from the vertebral bodies. MR images were obtained using a 1.5 Tesla MR scanner at a spatial resolution of 117 x 117 x 300 microm. Additionally, BMD was determined using quantitative computed tomography (QCT), and the specimens were nondestructively tested and the elastic modulus (YM) was measured along three orthogonal axes corresponding to the anatomic superior-inferior (axial), medial-lateral (sagittal), and anterior-posterior (coronal) directions. A subset of the specimens (n=67) was then destructively tested in the superior-inferior (axial) direction to measure the ultimate compressive strength. The MR images were segmented into bone and marrow phases and then analyzed in 3D. Ellipsoids were fitted to the mean intercept lengths, using single value decomposition and the primary orientation of the trabeculae and used to calculate the anisotropy of trabecular architecture. Stereological measures were derived using a previously developed model and measures such as mean trabecular width, spacing, and number were derived. Because the spatial resolution of MR images is comparable to trabecular bone dimensions, these measures may be subject to partial volume effects and were thus treated as apparent measures, such as BV/TV, Tb.Sp, Tb.N, and Tb.Th rather than absolute measures, as would be derived from histomorphometry. In addition, in a subset of specimens, the Euler number per unit volume was determined to characterize the connectivity of the trabecular network. There were significant differences in the BMD, trabecular architectural measures, elastic modulus, and strength at the different skeletal sites. The primary orientation axes for most of the specimens was the anatomic superior-inferior (axial) direction. Using the fabric tensor formulation, in addition to BMD, improved the prediction of YM (SI), while including some of the architectural parameters significantly improved the prediction of strength. In comparing MR-derived 3D measures with those obtained from 20 microm optical images (n=18; 9 vertebrae, 9 femur specimens), good correlations were found for the apparent Tb.Sp and Tb.N, moderate correlation was seen for the apparent BV/TV, and poor correlation was found for the apparent Tb.Th. Using these higher resolution images, the fabric tensor formulation for predicting the elastic modulus also showed improved correlation between the measured and calculated modulus in the axial (SI) direction. In summary, high-resolution MR images may be used to assess 3D architecture of trabecular bone, and the inclusion of some of the 3D architectural measures provides an improved assessment of biomechanical properties. Further studies are clearly warranted to establish the role of architecture in predicting overall bone quality, and the role of trabecular architecture measures in clinical practice. (ABSTRACT TRUNCATED)

Anatomy, Cross-Sectional↗
PubMed1998

Morphometric texture analysis of spinal trabecular bone structure assessed using orthogonal radiographic projections.

The measurement of bone microstructure as well as bone mineral density may improve the estimation of bone strength. Cubic specimens (N = 26, 12 mm X 12 mm X 12 mm) of human cadaver vertebrae were cut along three orthogonal anatomic orientations, i.e., superior-inferior (SI), medial-lateral (ML), and anterior-posterior (AP). Contact radiographs of the bone cubes along all three orientations were obtained and then digitized by a laser scanner with pixel size of 50 microns x 50 microns. The specimens were tested in compression along the 3 orthogonal orientations and the Young's modulus (YM) was calculated for each direction. Quantitative computed tomography (QCT) was used to obtain a measure of trabecular bone mineral density (BMD). Global gray level thresholding and local thresholding algorithms were used to extract the trabecular bone network. Apparent trabecular bone fraction (ABV/TV), mean intercept length (I.TH), mean intercept separation (I.SP), and number of nodes (N.ND) were measured from the extracted trabecular network. Fractal dimension (Fr.D) of the trabecular bone texture was also measured. Paired t-tests showed that the mean values of each texture parameter (except ABV/TV) and of YM along the SI direction were significantly different (p < 0.05) from those along the ML and AP direction. However, the mean values along the ML and AP directions were not significantly different. Multivariate regression of YM as a function of the texture parameters and BMD showed that without adjusting for the effect of BMD, YM was significantly explained by all the texture parameters (R2 = 0.2-0.6). When BMD was included in the regression, although the variations in YM of ML, AP, and SI orientations could be explained by BMD alone, some of the texture parameters did improve the overall prediction of the biomechanical properties, while, some parameters such as ABV/TV and Fr.D in the ML orientation showed a more significant overall effect in explaining mechanical strength than did BMD. In conclusion, trabecular texture parameters correlated significantly with BMD and YM. Trabecular texture parameters from projectional radiographs reflect the anisotropy of trabecular structure. Quantitative radiographic assessment of trabecular structure using fine-detail radiography can potentially improve the estimation of bone strength.

Adult↗
PubMed1998

Proximal femur: assessment for osteoporosis with T2* decay characteristics at MR imaging.

PURPOSE: To use T2* measurements at magnetic resonance (MR) imaging to investigate the trabecular structure of the hip in women with and women without osteoporotic hip fractures and to compare this technique with bone mineral density (BMD) measurements in the diagnosis of fractures. MATERIALS AND METHODS: T2* maps of the proximal femur were obtained at 1.5 T in 23 postmenopausal study patients with osteoporotic hip fractures, 27 age-matched healthy postmenopausal control subjects, and five healthy premenopausal control subjects. A modified gradient-recalled acquisition in the steady state, or GRASS, sequence was used with echo times of 4-40 msec at 4-msec increments. T2* values were measured in five regions of interest: femoral neck, the Ward triangle, trochanter, intertrochanteric region, and total proximal femur. Additionally, BMD measurements of the hip were obtained with dual x-ray absorptiometry. RESULTS: Significant differences between T2* measurements were obtained in all three groups (P < .05). BMD measurements of the hip also showed significant differences (P < .05). For T2* and BMD measurements, odds ratios and areas under the curve in receiver operating characteristic analysis were comparable. Correlations between 1/T2* values and BMD were significant (P < .05). T2* measurements in the proximal femur showed regional variations. CONCLUSION: MR imaging decay characteristics of bone marrow could be used to differentiate between postmenopausal women with and those without osteoporotic hip fractures.

Absorptiometry, Photon↗