New Palpometer with Implications for Assessment of Deep Pain Sensitivity

The aims of this study were to compare test-retest variability and accuracy measures between (1) manual palpation and a novel palpometer and (2) different force levels. Sixteen clinicians were instructed to target 0.5, 1.0, and 2.0 kg on a force meter using manual palpation and the new palpometer (adjustable spring-coil with a small pin touching the examiner’s hand when the correct pressure is reached). In all experiments, 10 consecutive measures of the force levels were recorded. The coefficient of variation (CV), actual force levels, and relative differences between target level and actual force level were compared between experiments and target levels. All outcome parameters had significantly lower values for the new palpometer than for manual palpation in a force-dependent manner (p < 0.004). CVs and actual force levels were significantly different between all target levels (p < 0.004). The new palpometer had low test-retest variability and provides a more accurate pressure stimulus than manual palpation.

c-KIT positive Gastrointestinal Stromal Tumor presenting with acute bleeding in a patient with neurofibromatosis type 1: a case report

Background

Gastrointestinal stromal tumours are rare (GIST). However, the incidence of GIST among neurofibromatosis type 1 (NF-1) patients is approximately 3.9-25%. GIST can present clinically in different ways such as abdominal pain, gastrointestinal bleeding and obstruction.

Case report

We present 51 year female patient admitted with Background of neurofibromatosis type 1 admitted with melena. OGD has been done and showed duodenitis with large volume fresh blood in distal duodenum but no obvious bleeding point. Exploratory laparotomy revealed smooth nodular masses on the serosal surface of jejunum. Small bowel resection and side-to-side anastomosis were performed. Histopathoogical examination revealed small bowel gasrointestinal stromal tumour with low risk malignant potential.

Conclusion

The incidence of GIST among neurofibromatosis type 1 (NF-1) patients is not uncommon and we should pay attention to gastrointestinal manifestation in such patients.

Nitrous oxide induced sub-acute combined degeneration of spinal cord: a case report

We report a patient who developed signs and symptoms of a myelopathy after exposure to nitrous oxide. Magnetic Resonance Imaging of the cervical spinal cord disclosed hyperintensities of the dorsal columns on T2 weighted images suggesting sub-acute combined degeneration.

Longitudinal study of magnetic resonance imaging and standard X-rays to assess disease progression in osteoarthritis

OBJECTIVE

To investigate, over 1-year, the relationship between X-ray and magnetic resonance imaging (MRI) findings in patients with knee osteoarthritis (OA).

METHODS

Sixty-two osteoarthritic patients (46 women) were followed for 1 year. At baseline and after 1 year, volume and thickness of cartilage of the medial tibia, the lateral tibia and the femur were assessed by MRI. A global score from the multi-feature whole-organ MRI scoring system (WORMS) was calculated for each patient at baseline and after 1 year. This score combined individual scores for articular cartilage, osteophytes, bone marrow abnormality, subchondral cysts and bone attrition in 14 locations. It also incorporated scores for the medial and lateral menisci, anterior and posterior cruciate ligaments, medial and lateral collateral ligaments and synovial distension. Lateral and medial femoro-tibial joint space width (JSW) measurements, performed by digital image analysis, were assessed from fixed-flexion, postero-anterior knee radiographs.

RESULTS

One-year changes in medial femoro-tibial JSW reach 6.7 (20.5) % and changes in medial cartilage volume and thickness reach 0.4 (16.7) % and 2.1 (11.3) %, respectively. Medial femoro-tibial joint space narrowing (JSN) after 1 year, assessed by radiography, was significantly correlated with a loss of medial tibial cartilage volume (r=0.25, P=0.046) and medial tibial cartilage thickness (r=0.28, P=0.025), over the same period. We found also a significant correlation between the progression of the WORMS and radiographic medial JSN over 1 year (r=-0.35, P=0.006). All these results remained statistically significant after adjusting for age, sex and body mass index.

CONCLUSION

This study shows a moderate but significant association between changes in JSW and changes in cartilage volume or thickness in knee joint of osteoarthritic patients.

Imaging osteoarthritis: Magnetic resonance imaging versus x-ray

Until recently, imaging evaluation of osteoarthritis has relied primarily on conventional radiography. Using radiography in clinical practice or clinical research, however, has been fraught with difficulty. Techniques for reproducibly acquiring serial radiographs of joints have improved considerably over the past several years. However, the greatest promise for advancing knowledge about osteoarthritis and its treatment lies in MRI and its unique ability to examine the joint as a whole organ. In contrast to conventional radiography, MRI can directly visualize the articular cartilage, synovium, menisci, and other intra-articular structures important to the functional integrity of joints. There have been considerable advances in MRI of articular cartilage in particular over the past several years. However, much of this has come from small cross-sectional studies. Larger, longitudinal studies are ongoing, and publications are just emerging. This paper reviews the current status of x-ray and MRI in osteoarthritis and points to where changes might be anticipated in the future.

Osteoarthritis, magnetic resonance imaging, and biochemical markers: a one year prospective study

OBJECTIVE

To investigate the relation between biochemical markers of bone, cartilage, and synovial remodelling and the structural progression of knee osteoarthritis.

METHODS

62 patients of both sexes with knee osteoarthritis were followed prospectively for one year. From magnetic resonance imaging (MRI), done at baseline and after one year, the volume and thickness of cartilage of the femur, the medial tibia, and the lateral tibia were assessed. A whole organ magnetic resonance imaging score (WORMS) of the knee was calculated for each patient at baseline and at the one year visits. This score consists in a validated, semiquantitative scoring system for whole organ assessment of the knee in osteoarthritis using MRI. Biochemical markers (serum hyaluronic acid, osteocalcin, cartilage glycoprotein 39 (YKL-40), cartilage oligomeric matrix protein (COMP), and C-telopeptide of type I collagen (CTX-I), and urine C-telopeptide of type II collagen (CTX-II)) were measured at baseline and after three months.

RESULTS

Baseline markers were not correlated with one year changes observed in cartilage volume and thickness. However, an increase in CTX-II after three months was significantly correlated with a one year decrease in mean thickness of medial tibial and lateral tibial cartilage. Patients in the highest quartile of three month changes in CTX-II experienced a mean loss of 0.07 (0.08) mm of their medial thickness, compared with a mean increase of 0.05 (0.19) mm for patients in the lowest quartile (p = 0.04) Multiple regression analysis showed that high baseline levels of hyaluronic acid are predictive of a worsening in WORMS (p = 0.004).

CONCLUSIONS

These results suggest that a single measurement of serum hyaluronic acid or short term changes in urine CTX-II could identify patients at greatest risk of progression of osteoarthritis.

Closure of the ventral hernia in the management of giant exomphalos: a word of caution

Giant exomphalos containing liver as its major component and with visceroabdominal disproportion presents difficult management options to a paediatric surgeon. At Starship Children's Hospital, we deal with these with primary skin closure, if possible, followed by staged repair of the ventral hernia beginning in the 2nd year of life. During the closure of a ventral hernia, we encountered major hepatic venous bleeding resulting from the inadvertent injury to the right hepatic vein, resulting in the death of the child. An autopsy report showed the position of the hepatic veins superficially just beneath the skin. Subsequently, we performed magnetic resonance imaging (MRI) of the abdomen to look at the hepatic venous and caval anatomy in two children before closure of the ventral hernia. This was of immense help in limiting the dissection in the area and thus avoiding catastrophe. We recommend routine imaging with MRI before closure of a ventral hernia in children with giant exomphalos.

Factors predisposing to cavity margin positivity following conservation surgery for breast cancer

AIMS

Incomplete excision leads to local recurrence following breast conservation therapy (BCT). The aim of this study was to examine factors associated with cavity margin (CM) positivity and return to theatre rates.

METHODS

Breast conservation surgery with entire CM excision was the initial procedure in 301 patients with 303 breast cancers. Of these, 258 patients were treated successfully with breast conservation surgery and 43 patients subsequently required a mastectomy for persistent involved margins. The mean and median follow-up was 38 and 42 (range 6-78) months, respectively.

RESULTS

Positive CMs were found in 73 out of 303 tumours. Large tumour size (p<0.001) and tumour type (invasive lobular cancer and ductal carcinoma in-situ) (p=0.043) were significant predictors of CM positivity both by univariate and multivariate analysis. As a result of CM status in relation to initial margin (IM) status, 60 cancers treated that were IM positive but CM negative avoided return for further excision at a second operative procedure.

CONCLUSION

Complete CM excision should avoid the need for further re-excision surgery in most patients where initial specimen margin was positive.

Fixed-flexion radiography of the knee provides reproducible joint space width measurements in osteoarthritis

The validity of a non-fluoroscopic fixed-flexion radiographic acquisition and analysis protocol for measurement of joint space width (JSW) in knee osteoarthritis is determined. A cross-sectional study of 165 patients with documented knee osteoarthritis participating in a multicenter, prospective study of chondroprotective agents was performed. All patients had posteroanterior, weight-bearing, fixed-flexion radiography with 10 degrees caudal beam angulation. A specially designed frame (SynaFlexer) was used to standardize the positioning. Minimum medial and lateral JSW were measured manually and twice by an automated analysis system to determine inter-technique and intra-reader concordance and reliability. A random subsample of 30 patients had repeat knee radiographs 2 weeks apart to estimate short-term reproducibility using automated analysis. Concordance between manual and automated medial JSW measurements was high (ICC=0.90); lateral compartment measurements showed somewhat less concordance (ICC=0.72). There was excellent concordance between repeated automated JSW measurements performed 6 months apart for the medial (ICC=0.94) and lateral (ICC=0.86) compartments. Short-term reproducibility for the subsample of 30 cases with repeat acquisitions demonstrated an average SD of 0.14 mm for medial JSW (CV=4.3%) and 0.23 mm for lateral JSW (CV=4.0%). Fixed-flexion radiography of the knee using a positioning device provides consistent, reliable and reproducible measurement of minimum JSW in knee osteoarthritis without the need for concurrent fluoroscopic guidance.

Whole-Organ Magnetic Resonance Imaging Score (WORMS) of the knee in osteoarthritis

OBJECTIVES

To describe a semi-quantitative scoring method for multi-feature, whole-organ evaluation of the knee in osteoarthritis (OA) based on magnetic resonance imaging (MRI) findings. To determine the inter-observer agreement of this scoring method. To examine associations among the features included in the scoring method.

METHODS

Nineteen knees of 19 patients with knee OA were imaged with MRI using conventional pulse sequences and a clinical 1.5 T MRI system. Images were independently analyzed by two musculoskeletal radiologists using a whole-organ MRI scoring method (WORMS) that incorporated 14 features: articular cartilage integrity, subarticular bone marrow abnormality, subarticular cysts, subarticular bone attrition, marginal osteophytes, medial and lateral meniscal integrity, anterior and posterior cruciate ligament integrity, medial and lateral collateral ligament integrity, synovitis/effusion, intraarticular loose bodies, and periarticular cysts/bursitis. Intraclass correlation coefficients (ICC) were determined for each feature as a measure of inter-observer agreement. Associations among the scores for different features were expressed as Spearman Rho.

RESULTS

All knees showed structural abnormalities with MRI. Cartilage loss and osteophytes were the most prevalent features (98% and 92%, respectively). One of the least common features was ligament abnormality (8%). Inter-observer agreement for WORMS scores was high (most ICC values were >0.80). The individual features showed strong inter-associations.

CONCLUSION

The WORMS method described in this report provides multi-feature, whole-organ assessment of the knee in OA using conventional MR images, and shows high inter-observer agreement among trained readers. This method may be useful in epidemiological studies and clinical trials of OA.

Imaging in antiangiogenesis trial: a clinical trials radiology perspective

Traditional approaches for treating cancer have largely focused on the ability of chemotherapy, and to a lesser extent radiation therapy, to destroy tumour cells. Recent developments in antiangiogenesis treatments require a fundamental shift in the radiological and imaging paradigms associated with evaluating response. Proper design and execution of any clinical trial involving imaging angiogenesis requires satisfactory consideration of a number of strategies and an in-depth understanding of different imaging techniques such as dynamic contrast enhanced MRI and CT, contrast-enhanced ultrasound and positron emission tomography. In particular, for imaging, the strategies can be divided into issues that need to be addressed during the protocol planning phase, and strategies that need to be addressed during the execution phase. Furthermore, clinical trials are usually subject to stringent regulations surrounding traceability and reproducibility that need to be followed before the regulatory authorities will accept the integrity of the data. This paper elaborates on the above strategies and outlines certain aspects, or tactics, that need to be considered while preparing for a multicentre clinical trial that involves imaging angiogenesis.

Allelopathic effects of Lantana camara Linn. on spore germination of Asterella angusta Steph.--a liverwort

Extract from root, stem and leaf of L. camara proved inhibitory for germination of the spores of A. angusta. Leaf extract was found to exhibit maximum allelopathic potentiality followed by stem and root extract and may be interpreted to be the result of phytotoxic substances which are possibly synthesized in the leaf and translocated to other organs.

The referral pattern for undescended testes in Auckland

AIM

To accurately audit the age at orchiopexy at our institution and then to analyse the referral pattern specially related to the age of the patient.

METHODS

A retrospective review of hospital records was performed. Data were obtained from the hospital database based on the procedure code of orchiopexy. Mean and median values were calculated for age at referral, time between clinic visit and referral (T1) and between clinic visit and operation (T2).

RESULTS

The mean age at referral was 42.6 months (median 23, range 0 - 179.1 months). The mean time T1 was 2.6 months (median 1.7, range 0 - 16.9 months). The mean time T2 was 7.0 months (median 3.3 months).

CONCLUSION

There is a need to increase awareness about undescended testes amongst all parties involved in the health care of children.

A comparison of the vastus splitting and median parapatellar approaches in total knee arthroplasty

This prospective randomized study was undertaken to evaluate the vastus splitting approach as an alternative to the median parapatellar approach in primary total knee arthroplasty. Fifty-one knees in 42 patients were randomized preoperatively. Clinical parameters were evaluated preoperatively and at regular postoperative intervals. Electromyography was performed preoperatively and postoperatively to evaluate each approach relative to its effect on the innervation of the quadriceps mechanism. There were no significant preoperative differences. Postoperatively, there were no significant differences regarding strength, range of motion, knee scores, tourniquet time, proprioception, or patellar replacement. There were significantly more lateral releases performed and greater blood loss in the patients in the parapatellar group. The results of all preoperative electromyograms were normal, as were all of the results of postoperative electromyograms in the patients in the parapatellar group. However, the results of nine of 21 (43%) of the electromyograms performed postoperatively on patients who had the vastus splitting approach were abnormal. Significantly fewer lateral releases were performed and there was less blood loss in the patients in the vastus group. However, the postoperative electromyographic results revealed neurologic injuries in the vastus medialis muscle that only were present after the vastus splitting approach. The clinical significance of denervation of the vastus medialis muscle by the vastus approach remains to be determined by longer term clinical and electromyographic studies.

Measurement of intraspecimen variations in vertebral cancellous bone architecture

A three-dimensional technique was developed for the quantification of the number and cross-sectional geometry of individual trabeculae oriented along a given direction. As an example application, the number of vertical and horizontal trabeculae and their respective cross-sectional geometry were determined for a set of six vertebral cancellous bone specimens (L3-L4 female vertebral bodies; age range 39-63 years). Three-dimensional optical images at a spatial resolution of 20 microm were obtained using an automated serial milling technique. The thickness distributions were generally right skewed. The mean true thickness for both the vertically and horizontally oriented trabeculae showed a strong relationship with volume fraction (vertical: r2 = 0.86; p < 0.05; horizontal: r2 = 0.80; p < 0.05), and mean trabecular thickness (Tb.Th.) (vertical: r2 = 0.81; p < 0.05; horizontal: r2 = 0.72; p < 0.05). The horizontal trabeculae were greater in number and were thinner than the vertical trabeculae. The coefficient of variation of the intraspecimen vertical trabecular thicknesses ranged from 25% to 42%, and showed a weak, albeit insignificant, positive correlation with volume fraction (r2 = 0.46). The findings demonstrated substantial intraspecimen variations exist in trabecular thickness that are not related to volume fraction. Further studies are recommended to determine the potential role of such intraspecimen variations in architecture on biomechanical properties.

Fractal analysis of radiographs: assessment of trabecular bone structure and prediction of elastic modulus and strength

The purpose of this study was to determine whether fractal dimension of radiographs provide measures of trabecular bone structure which correlate with bone mineral density (BMD) and bone biomechanics, and whether these relationships depend on the technique used to calculate the fractal dimension. Eighty seven cubic specimen of human trabecular bone were obtained from the vertebrae and femur. The cubes were radiographed along all three orientations--superior-inferior (SI), medial-lateral (ML), and anterior-posterior (AP), digitized, corrected for background variations, and fractal based techniques were applied to quantify trabecular structure. Three different techniques namely, semivariance, surface area, and power spectral methods were used. The specimens were tested in compression along three orientations and the Young's modulus (YM) was determined. Compressive strength was measured along the SI direction. Quantitative computed tomography was used to measure trabecular BMD. High-resolution magnetic-resonance images were used to obtain three-dimensional measures of trabecular architecture such as the apparent bone volume fraction, trabecular thickness, spacing, and number. The measures of trabecular structure computed in the different directions showed significant differences (p<0.05). The correlation between BMD, YM, strength, and the fractal dimension were direction and technique dependent. The trends of variation of the fractal dimension with BMD and biomechanical properties also depended on the technique and the range of resolutions over which the data was analyzed. The fractal dimension showed varying trends with bone mineral density changes, and these trends also depended on the range of frequencies over which the fractal dimension was measured. For example, using the power spectral method the fractal dimension increased with BMD when computed over a lower range of spatial frequencies and decreased for higher ranges. However, for the surface area technique the fractal dimension increased with increasing BMD. Fractal measures showed better correlation with trabecular spacing and number, compared to trabecular thickness. In a multivariate regression model inclusion of some of the fractal measures in addition to BMD improved the prediction of strength and elastic modulus. Thus, fractal based texture analysis of radiographs are technique dependent, but may be used to quantify trabecular structure and have a potentially valuable impact in the study of osteoporosis.

Fractal analysis of proximal femur radiographs: correlation with biomechanical properties and bone mineral density

Conventional radiography and fractal analysis were used to quantify trabecular texture patterns in human femur specimens and these measures were used in conjunction with bone mineral density (BMD) to predict bone strength. Radiographs were obtained from 51 human femur specimens (25 male, 26 female). The radiographs were analyzed using three different fractal geometry based techniques, namely semi-variance, surface area and Fourier analysis. Maximum compressive strength (MCS) and shear stress (MSS) were determined with a material testing machine: BMD was measured using quantitative computed tomography (QCT). MCS and MSS both correlated significantly with BMD (MCS: R = 0.49-0.54; MSS: R = 0.69-0.72). Fractal dimension also correlated significantly with both biomechanical properties (MCS: R = 0.49-0.56; MSS: R = 0.47-0.54). Using multivariate regression analysis, the fractal dimension in addition to BMD improved correlations versus biomechanical properties. Both BMD and fractal dimension showed statistically significant correlation with bone strength. The fractal dimension provided additional information beyond BMD in correlating with biomechanical properties.

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.

Assessment of cancellous bone mechanical properties from micro-FE models based on micro-CT, pQCT and MR images

Recently, new micro-finite element (micro-FE) techniques have been introduced to calculate cancellous bone mechanical properties directly from high-resolution images of its internal architecture. Also recently, new peripheral quantitative computed tomography (pQCT) and magnetic resonance (MR) imaging techniques have been developed that can create images of whole bones in vivo with enough detail to visualize the internal cancellous bone architecture. In this study we aim to investigate if the calculation of cancellous bone mechanical properties from micro-FE models based on such new pQCT and MR images is feasible. Three bone specimens were imaged with the pQCT scanning system and the MR-imaging system. The specimens were scanned a second time using a micro-CT scanner with a much higher resolution. Digitized reconstructions were made based on each set of images and converted to micro-FE models from which the bone elastic properties were calculated. It was found that the results of both the pQCT and the MR-based FE-models compared well to those of the more accurate micro-CT based models in a qualitative sense, but correction factors will be needed to get accurate values.

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)

Impact of spatial resolution on the prediction of trabecular architecture parameters

Although the efficacy of various measures for the assessment of trabecular bone architecture has been widely studied, the impact of spatial resolution on the estimation of these measures has remained relatively unexplored. In this study, ten cubes each of human trabecular bone from the femur and vertebral bodies were obtained from nine cadavers (four males and five females), aged 23-67 years (mean 42.3 years). These specimens were serially milled and imaged at a resolution of 40 microm to produce three-dimensional digitizations from which traditional morphometric and structural anisotropy measures could be computed based on a three-dimensional approach. The cubes were then artificially degraded to an in-plane resolution of 100 microm and an out-of-plane (slice) resolution of 100-1000 microm. These resolutions mimicked in vivo resolutions as seen using magnetic resonance (MR) imaging. All images, original and degraded, were individually segmented using a thresholding algorithm, and both the traditional morphometric and structural anisotropy measures were recomputed. The choice of slice direction was varied along the superior-inferior (axial), anterior-posterior (coronal), and medial-lateral (sagittal) directions to minimize the impact of the lower slice resolution on the architectural measures. It was found that traditional morphometric measures such as trabecular spacing and trabecular number showed weak resolution dependency; measures such as trabecular thickness, however, showed strong resolution dependency and required very high resolutions for precise measurement. In the case of the femur specimens, both structural anisotropy as well as the preferred orientation showed a strong resolution dependency. The resolution dependency of these parameters could be minimized for the femur and the vertebral body specimens if the slice direction was taken along the superior-inferior direction.