Variability of Child Rib Bone Hounsfield Units using in vivo Computed Tomography

The variability assessment of the rib bone mechanical properties during the growth process is still missing. These properties could not be obtained in vivo on children. Relationships have been obtained between Hounsfield Units from computed tomography (CT) and mechanical properties (e.g. for the cortical bone on adults). As a first step for investigation of the mechanical properties of child ribs, the aim of this study was to determine the Hounsfield Units variation of child ribs from CT‐scan data, by rib level, along the rib and within the rib sections. Twenty‐seven right ribs of levels 4, 6 and 9 were processed from 11 thoracic CT scans of children without bone lesions aged between 1 and 10 years. A first set of 10 equidistributed cross‐sections normal to the rib midline were extracted. Sixteen equally distributed elements defined 4 areas into the cortical band: internal, external, caudal and cranial. Within the rib sections, Hounsfield Units were found significantly higher in internal and external areas than in caudal and cranial. In a further step using calibrated CT scans, it would be possible to derive the mechanical properties of in vivo child ribs using bone density correlation with Hounsfield Units

Effect of alendronate on post-traumatic osteoarthritis induced by anterior cruciate ligament rupture in mice.

IntroductionPrevious studies in animal models of osteoarthritis suggest that alendronate (ALN) has antiresorptive and chondroprotective effects, and can reduce osteophyte formation. However, these studies used non-physiologic injury methods, and did not investigate early time points during which bone is rapidly remodeled prior to cartilage degeneration. The current study utilized a non-invasive model of knee injury in mice to investigate the effect of ALN treatment on subchondral bone changes, articular cartilage degeneration, and osteophyte formation following injury.MethodsNon-invasive knee injury via tibial compression overload or sham injury was performed on a total of 90 mice. Mice were treated with twice weekly subcutaneous injections of low-dose ALN (40 μg/kg/dose), high-dose ALN (1,000 μg/kg/dose), or vehicle, starting immediately after injury until sacrifice at 7, 14 or 56 days. Trabecular bone of the femoral epiphysis, subchondral cortical bone, and osteophyte volume were quantified using micro-computed tomography (μCT). Whole-joint histology was performed at all time points to analyze articular cartilage and joint degeneration. Blood was collected at sacrifice, and serum was analyzed for biomarkers of bone formation and resorption.ResultsμCT analysis revealed significant loss of trabecular bone from the femoral epiphysis 7 and 14 days post-injury, which was effectively prevented by high-dose ALN treatment. High-dose ALN treatment was also able to reduce subchondral bone thickening 56 days post-injury, and was able to partially preserve articular cartilage 14 days post-injury. However, ALN treatment was not able to reduce osteophyte formation at 56 days post-injury, nor was it able to prevent articular cartilage and joint degeneration at this time point. Analysis of serum biomarkers revealed an increase in bone resorption at 7 and 14 days post-injury, with no change in bone formation at any time points.ConclusionsHigh-dose ALN treatment was able to prevent early trabecular bone loss and cartilage degeneration following non-invasive knee injury, but was not able to mitigate long-term joint degeneration. These data contribute to understanding the effect of bisphosphonates on the development of osteoarthritis, and may support the use of anti-resorptive drugs to prevent joint degeneration following injury, although further investigation is warranted

ToScA North America (6 – 8 June 2017, The University of Texas, Austin, TX) Program

ToScA North America will address key areas of science, including Multi-modal Imaging, Geosciences, Forensics, Increasing Contrast, Educational Outreach, Data, Materials Science and Medical and Biological Science.University of Texas High-Resolution X-ray CT Facility (UTCT); Jackson School of Geosciences, The University of Texas at Austin; Natural History Museum (London); Royal Microscopical Society (Oxford, UK)Geological Science

Optimizing dual energy cone beam CT protocols for preclinical imaging and radiation research

Objective: The aim of this work was to investigate whether quantitative dual-energy CT (DECT) imaging is feasible for small animal irradiators with an integrated cone-beam CT (CBCT) system. Methods: The optimal imaging protocols were determined by analyzing different energy combinations and dose levels. The influence of beam hardening effects and the performance of a beam hardening correction (BHC) were investigated. In addition, two systems from different manufacturers were compared in terms of errors in the extracted effective atomic numbers (Z(eff)) and relative electron densities (rho(e)) for phantom inserts with known elemental compositions and relative electron densities. Results: The optimal energy combination was determined to be 50 and 90kVp. For this combination, Z(eff) and r rho(e) can be extracted with a mean error of 0.11 and 0.010, respectively, at a dose level of 60cGy. Conclusion: Quantitative DECT imaging is feasible for small animal irradiators with an integrated CBCT system. To obtain the best results, optimizing the imaging protocols is required. Well-separated X-ray spectra and a sufficient dose level should be used to minimize the error and noise for Z(eff) and rho(e). When no BHC is applied in the image reconstruction, the size of the calibration phantom should match the size of the imaged object to limit the influence of beam hardening effects. No significant differences in Z(eff) and rho(e) errors are observed between the two systems from different manufacturers. Advances in knowledge: This is the first study that investigates quantitative DECT imaging for small animal irradiators with an integrated CBCT system

Volumetric analysis of arteriovenous malformation using computed tomographic angiography

Thesis (M.A.)--Boston UniversityAn arteriovenous malformation (AVM) is an abnormal collection of blood vessels in which arterial blood flows directly into the draining vein without the normal interposed capillaries. It is an important and growing public healthcare problem affecting millions of Americans and many more people internationally. There are several potential treatment options for the AVM, and the best treatment depends on the maximum length of nidus based on the Spetzler- Martin grading system. However, this grading system is insensitive to volume, because it was designed on the basis of two dimensional digital subtraction angiography images. Here, we report a method using computed tomographic angiography to measure the volume of AVM nidus, as a means for noninvasively assessment. The initial results show statistically significant differences between healthy and AVM subject groups in the direct comparisons of the volume (cm3) through the method we suggested (2.456 ± 1.482, 12.478 ± 5.743 and 53.963 ± 9.338 (mean ± stdev.); Normal (No AVM), Small (< 3cm), Medium (3 ~ 6 cm) respectively; P < 0.005 for all), and they also show the exponential correlation between the AVM volume and the maximum length of a nidus (trend-line: y = 4.4183e0.536x with R2 = 0.945). These results provide more accurate volumetric information. Therefore, this noninvasive imaging-based method is a promising means to measure the volume of AVM using clinically available imaging tools

Emerging Translational Opportunities in Comparative Oncology With Companion Canine Cancers: Radiation Oncology.

It is estimated that more than 6 million pet dogs are diagnosed with cancer annually in the USA. Both primary care and specialist veterinarians are frequently called upon to provide clinical care that improves the quality and/or quantity of life for affected animals. Because these cancers develop spontaneously in animals that often share the same environment as their owners, have intact immune systems and are of similar size to humans, and because the diagnostic tests and treatments for these cancers are similar to those used for management of human cancers, canine cancer provides an opportunity for research that simultaneously helps improve both canine and human health care. This is especially true in the field of radiation oncology, for which there is a rich and continually evolving history of learning from the careful study of pet dogs undergoing various forms of radiotherapy. The purpose of this review article is to inform readers of the potential utility and limitations of using dogs in that manner; the peer-reviewed literature will be critically reviewed, and current research efforts will be discussed. The article concludes with a look toward promising future directions and applications of this pet dog "model.

Bronchoscopy, Imaging, and Concurrent Diseases in Dogs with Bronchiectasis: (2003-2014).

BackgroundBronchiectasis is a permanent and debilitating sequel to chronic or severe airway injury, however, diseases associated with this condition are poorly defined.ObjectiveTo evaluate results of diagnostic tests used to document bronchiectasis and to characterize underlying or concurrent disease processes.AnimalsEighty-six dogs that had bronchoscopy performed and a diagnosis of bronchiectasis.MethodsRetrospective case series. Radiographs, computed tomography, and bronchoscopic findings were evaluated for features of bronchiectasis. Clinical diagnoses of pneumonia (aspiration, interstitial, foreign body, other), eosinophilic bronchopneumopathy (EBP), and inflammatory airway disease (IAD) were made based on results of history, physical examination, and diagnostic testing, including bronchoalveolar lavage fluid analysis and microbiology.ResultsBronchiectasis was diagnosed in 14% of dogs (86/621) that had bronchoscopy performed. Dogs ranged in age from 0.5 to 14 years with duration of signs from 3 days to 10 years. Bronchiectasis was documented during bronchoscopy in 79/86 dogs (92%), thoracic radiology in 50/83 dogs (60%), and CT in 34/34 dogs (100%). Concurrent airway collapse was detected during bronchoscopy in 50/86 dogs (58%), and focal or multifocal mucus plugging of segmental or subsegmental bronchi was found in 41/86 dogs (48%). Final diagnoses included pneumonia (45/86 dogs, 52%), EBP (10/86 dogs, 12%) and IAD (31/86 dogs, 36%). Bacteria were isolated in 24/86 cases (28%), with Streptococcus spp, Pasteurella spp, enteric organisms, and Stenotrophomonas isolated most frequently.Conclusions and clinical importanceBronchiectasis can be anticipated in dogs with infectious or inflammatory respiratory disease. Advanced imaging and bronchoscopy are useful in making the diagnosis and identifying concurrent respiratory disease

Ex vivo analysis of local orientation of collagen fiber bundles in 3D in posterior horn human meniscus using micro-computed tomography

Abstract. Objective: Knee osteoarthritis (OA) is an increasingly relevant joint disease affecting mostly aged population in developed countries. However, there is currently no treatment for OA and increasing the knowledge of the disease with the help of micro-computed tomography (µCT) imaging could offer help in finding the solution. The objective of this thesis was to quantitatively analyze the microstructural organization of human posterior horn meniscus samples in 3D using hexamethyldisilazane (HMDS) based µCT imaging. In addition, this study aims to compare the local microstructural organization of meniscus between OA patients and healthy references. Method: We collected medial and lateral posterior horns of human menisci from 10 endstage medial compartment knee OA patients undergoing total knee replacement surgery and from 10 deceased donors without diagnosed knee OA to act as healthy reference. The posterior horns were dissected and fixed in formalin, dehydrated in ascending alcohol concentrations, treated with HMDS, and scanned with a desktop µCT. Furthermore, we performed local orientation analysis of collagenous microstructure in 3D to all samples, by calculating local structure tensors from greyscale gradients withing a selected integration window to determine the polar angle for each voxel. Moreover, distribution of angles and mean estimated average angles were statistically compared. Results: Collagen fiber bundles in HMDS-treated meniscal samples were depicted in 3D using µCT. In the quantitative local orientation analysis, medial OA had overall lowest orientation angles compared to all other groups: mean estimated differences versus medial OA were -24° [95%CI -31°, -18°] in medial donor, -25° [95%CI -34°, -15°] in lateral OA, and -25° [95%CI -35°, -16°] in lateral donor groups. Distribution and mean angles between lateral OA and lateral donor menisci were similar with a mean difference of 2°. Conclusions: In this study, we were able to quantitatively analyze collagen fiber bundles and their orientations in 3D in the posterior horn of human meniscus using HMDS-based µCT imaging. Furthermore, collagen disorganization increased in the medial OA meniscus, suggesting a relationship between collagenous microstructure disorganization and meniscus degradation.Ihmisen nivelkierukan takasarven kollageenisäiekimppujen kolmi-ulotteinen lokaaliorientaatioanalyysi mikrotietokonetomografian avulla. Tiivistelmä. Tarkoitus: Nivelrikko on yleinen sairaus vanhenevassa yhteiskunnassa, mutta sairauden monimuotoisuuden vuoksi sen hoitaminen on vaikeaa. Sairauden vahvempi ymmärtäminen voisi auttaa hoidon kehittämisessä sairautta vastaan. Tämän pro gradu -tutkielman tavoitteena oli analysoida kvantitatiivisesti ihmisen nivelkierukkanäytteiden mikrorakenteiden orientaatiota kolmiulotteisesti käyttäen heksametyylidisilatsaaniin (HMDS) perustuvaa näytteenkäsittelytekniikkaa mikrotietokonetomografiakuvantamisessa (µCT). Lisäksi tässä työssä verrataan kierukan lokaalimikrorakenneorganisaatiota nivelrikkoisten potilaiden ja terveiden verrokkien välillä. Menetelmä: Keräsimme mediaali- ja lateraalipuolen nivelkierukan takasarvet kymmeneltä nivelrikon loppuvaiheen potilaalta, joille tehtiin polven tekonivelleikkaus, ja 10 menehtyneeltä oikeuslääketieteen potilaalta, joilla ei ollut diagnosoitua polven nivelrikkoa. Nivelkierukoiden posterioriset sarvet leikattiin, käsiteltiin formaliinilla, kuivattiin nousevissa etanolipitoisuuksissa, käsiteltiin HMDS:llä ja kuvattiin µCT-laitteella. Lisäksi teimme näytteille kolmiulotteisen orientaatioanalyysin, jolla mitataan näytteiden kollageenisen mikrorakenteen orientaatiota. Analyysi laskee µCT-kuvien harmaasävygradienttien avulla jokaiselle vokselille paikallisen rakennetensorin, joiden purkamisesta saadaan laskettua vokselin anisotropian määrä ja sen pienimmän vektorin suunta. Pienin arvo ja sen suunta voidaan määrittää vokselin pääasialliseksi orientaatioksi. Kulmien jakautumista ja keskimääräisiä kulmia verrattiin tilastollisesti terveiden ja nivelrikkopotilaiden mediaali- ja lateraalipuolten välillä. Tulokset: Nivelkierukan kollageenikimput kuvattiin kolmiulotteisesti µCT:llä käyttäen HMDS-käsiteltyjä nivelkierukkanäytteitä. Kvantitatiivisessa orientaatioanalyysissä todettiin mediaalipuolen nivelrikkoisilla nivelkierukoilla yleisesti enemmän disorganisaatiota kaikkiin muihin ryhmiin verrattuna: mediaalipuolen nivelrikkoryhmässä orientaatioiden ero verrattuna mediaaliverrokkiryhmään oli -24° [95%CI -31°, -18°], -25° [95%CI -34°, -15°] verrattuna lateraalipuolen nivelrikkoryhmään ja -25° [95%CI -35°, -16°] verrattuna lateraalipuolen luovuttajaryhmän välillä. Lisäksi lateraalipuolen luovuttaja- ja lateraalipuolen nivelrikkoryhmän välillä kulmien jakauma ja keskiarvo olivat samanlaiset keskimäärisen eron ollessa 2°. Johtopäätökset: Tässä tutkimuksessa onnistuimme kuvaamaan ihmisen nivelkierukan kollageenikimput sekä kvantitatiivisesti analysoimaan niiden kolmiulotteista orientaatiota käyttäen HMDS-pohjaista µCT-kuvantamista. Lisäksi kollageenin disorganisaatio oli suurin mediaalipuolen nivelrikkoisessa nivelkierukassa, mikä viittaa kollageenisen mikrorakenteen disorganisaatioon ja nivelkierukan degeneraation väliseen vahvaan suhteeseen

Intraoperative Quantification of Bone Perfusion in Lower Extremity Injury Surgery

Orthopaedic surgery is one of the most common surgical categories. In particular, lower extremity injuries sustained from trauma can be complex and life-threatening injuries that are addressed through orthopaedic trauma surgery. Timely evaluation and surgical debridement following lower extremity injury is essential, because devitalized bones and tissues will result in high surgical site infection rates. However, the current clinical judgment of what constitutes “devitalized tissue” is subjective and dependent on surgeon experience, so it is necessary to develop imaging techniques for guiding surgical debridement, in order to control infection rates and to improve patient outcome. In this thesis work, computational models of fluorescence-guided debridement in lower extremity injury surgery will be developed, by quantifying bone perfusion intraoperatively using Dynamic contrast-enhanced fluorescence imaging (DCE-FI) system. Perfusion is an important factor of tissue viability, and therefore quantifying perfusion is essential for fluorescence-guided debridement. In Chapters 3-7 of this thesis, we explore the performance of DCE-FI in quantifying perfusion from benchtop to translation: We proposed a modified fluorescent microsphere quantification technique using cryomacrotome in animal model. This technique can measure bone perfusion in periosteal and endosteal separately, and therefore to validate bone perfusion measurements obtained by DCE-FI; We developed pre-clinical rodent contaminated fracture model to correlate DCE-FI with infection risk, and compare with multi-modality scanning; Furthermore in clinical studies, we investigated first-pass kinetic parameters of DCE-FI and arterial input functions for characterization of perfusion changes during lower limb amputation surgery; We conducted the first in-human use of dynamic contrast-enhanced texture analysis for orthopaedic trauma classification, suggesting that spatiotemporal features from DCE-FI can classify bone perfusion intraoperatively with high accuracy and sensitivity; We established clinical machine learning infection risk predictive model on open fracture surgery, where pixel-scaled prediction on infection risk will be accomplished. In conclusion, pharmacokinetic and spatiotemporal patterns of dynamic contrast-enhanced imaging show great potential for quantifying bone perfusion and prognosing bone infection. The thesis work will decrease surgical site infection risk and improve successful rates of lower extremity injury surgery