Long-term, Time-course Evaluation of Ligamentum Flavum Hypertrophy Induced by Mechanical Stress: An Experimental Animal Study.

STUDY DESIGN: Experimental animal study. OBJECTIVE: The aim of this study was to clarify chronological effects of mechanical stress on ligamentum flavum (LF) using a long-term fusion rabbit model. SUMMARY OF BACKGROUND DATA: LF hypertrophy is a major pathology of lumbar spinal stenosis (LSS), but its mechanism remains unclear. We previously demonstrated mechanical-stress-induced LF hypertrophy with a rabbit model. However, we only investigated LFs at a single time point in the short-term; the effects of long-term mechanical stress have not been elucidated. METHODS: Eighteen-week-old male New Zealand White rabbits were randomly divided into two groups: the mechanical stress group underwent L2-3 and L4-5 posterolateral fusion and resection of the L3-4 supraspinal muscle, whereas the control group underwent only surgical exposure. Rabbits were sacrificed 16 and 52 weeks after the procedure. Axial specimens of LFs at L3-4 were evaluated histologically. Immunohistochemistry for alpha-smooth muscle actin (α-SMA) was performed to assess the numbers of vessels and myofibroblasts. RESULTS: In the mechanical stress group, LFs at the L3-4 level exhibited hypertrophy with elastic fiber disruption and cartilage matrix production at 16 and 52 weeks. A trend test indicated that mechanical stress induced LF hypertrophy, elastic fiber disruption, and cartilage matrix production in a time-dependent manner, with the lowest levels before treatment and the highest at 52 weeks. Immunostaining for α-SMA showed similar numbers of vessels in both groups, whereas the percentage of myofibroblasts was significantly larger at 16 and 52 weeks in the mechanical stress group than in the control group. CONCLUSION: We demonstrated that long-term mechanical stress caused LF hypertrophy with progressive elastic fiber disruption and cartilage matrix production accompanied by enhanced myofibroblasts. In addition, the reported rabbit model could be extended to elucidate the mechanism of LF hypertrophy and to develop new therapeutic strategies for LSS by preventing LF hypertrophy.Level of Evidence: SSSSS.

The role of ultrasound in front-of-neck access for cricothyroid membrane identification: A systematic review.

PURPOSE: Conventional palpation techniques for cricothyroid membrane (CTM) identification are inaccurate and unreliable. Ultrasound plays a multi-faceted role in airway management, however there is limited literature around its use for CTM identification prior to cricothyrotomies. This review sought to compare ultrasound to palpation in the general population, identify its indications in subjects with ill-defined neck anatomy, and determine its role in defining neck anatomy. METHODS: Two reviewers independently assessed titles, abstracts and full-text English articles through the Ovid Medline and EMBASE databases. Studies related to ultrasound for CTM assessment and/or cricothyrotomy in subjects older than 12 years were included. RESULTS: Fourteen studies were selected. Compared to palpation, ultrasound has greater accuracy, but longer CTM identification times in those with normal airway anatomy. Interestingly, ultrasound offers comparable times to palpation in patients with difficult airways. Ultrasound also helps define anatomical parameters in the neutral and extended neck positions thereby underscoring the importance of neck positioning during cricothyrotomies and confirming consensus-based incision recommendations set by the Difficult Airway Society. CONCLUSION: Ultrasound appears to be superior to palpation for CTM localization especially in those with difficult airway anatomy and objectively defines neck anatomy. Its pre-emptive use should be incorporated during difficult airway management.

The vocal organ of hummingbirds shows convergence with songbirds.

How sound is generated in the hummingbird syrinx is largely unknown despite their complex vocal behavior. To fill this gap, syrinx anatomy of four North American hummingbird species were investigated by histological dissection and contrast-enhanced microCT imaging, as well as measurement of vocalizations in a heliox atmosphere. The placement of the hummingbird syrinx is uniquely located in the neck rather than inside the thorax as in other birds, while the internal structure is bipartite with songbird-like anatomical features, including multiple pairs of intrinsic muscles, a robust tympanum and several accessory cartilages. Lateral labia and medial tympaniform membranes consist of an extracellular matrix containing hyaluronic acid, collagen fibers, but few elastic fibers. Their upper vocal tract, including the trachea, is shorter than predicted for their body size. There are between-species differences in syrinx measurements, despite similar overall morphology. In heliox, fundamental frequency is unchanged while upper-harmonic spectral content decrease in amplitude, indicating that syringeal sounds are produced by airflow-induced labia and membrane vibration. Our findings predict that hummingbirds have fine control of labia and membrane position in the syrinx; adaptations that set them apart from closely related swifts, yet shows convergence in their vocal organs with those of oscines.

Combined multiphoton imaging and biaxial tissue extension for quantitative analysis of geometric fiber organization in human reticular dermis.

The geometric organization of collagen fibers in human reticular dermis and its relationship to that of elastic fibers remain unclear. The tight packing and complex intertwining of dermal collagen fibers hinder accurate analysis of fiber orientation. We hypothesized that combined multiphoton microscopy and biaxial extension could overcome this issue. Continuous observation of fresh dermal sheets under biaxial extension revealed that the geometry of the elastic fiber network is maintained during expansion. Full-thickness human thigh skin samples were biaxially extended and cleared to visualize the entire reticular dermis. Throughout the dermis, collagen fibers straightened with increased inter-fiber spaces, making them more clearly identifiable after extension. The distribution of collagen fibers was evaluated with compilation of local orientation data. Two or three modes were confirmed in all superficial reticular layer samples. A high degree of local similarities in the direction of collagen and elastic fibers was observed. More than 80% of fibers had directional differences of ≤15°, regardless of layer. Understanding the geometric organization of fibers in the reticular dermis improves the understanding of mechanisms underlying the pliability of human skin. Combined multiphoton imaging and biaxial extension provides a research tool for studying the fibrous microarchitecture of the skin.

Whole-lung pathology of pleuroparenchymal fibroelastosis (PPFE) in an explanted lung: Significance of elastic fiber-rich, non-specific interstitial pneumonia-like change in chemotherapy-related PPFE.

Pleuroparenchymal fibroelastosis (PPFE) is characterized by upper lobe-predominant subpleural fibroelastosis. Despite its characteristic uneven distribution, detailed whole-lung pathological features of PPFE have rarely been studied. We investigated PPFE in the explanted lungs from a 19-year-old male patient with a history of chemotherapy. Grossly, the explanted lungs showed upper lobe-predominant shrinkage with subpleural and central consolidation. Histologically, fibroelastosis was prominent in the perilobular areas and along the bronchovascular bundles. The other areas of the lung showed diffuse, non-specific interstitial pneumonia (NSIP)-like change with a characteristic increase of septal elastic fibers. In the digital image analysis, the ratio of elastic fibers to whole fibrosis (EF score) was lower in the subpleural areas than in the NSIP-like lesions, but the EF scores of the latter showed no significant difference between upper and middle/lower lobes. In the present case, the diffusely distributed elastic fiber-rich NSIP-like change, probably caused by the earlier chemotherapy, may have been conducive to the development of PPFE. This suggests that some unknown vulnerability of the upper lobe may exist, various primary lesions converging to the upper lobe predominance of PPFE.

Diagnostic features of elastofibroma dorsi: about 4 cases.

Elastofibromas are rare benign soft tissue tumors that are commonly located at the inferior pole of the scapula, typically in the right side, deep to the serratus anterior muscle. They occur mainly in elderly women and are usually asymptomatic. We  present four cases of elastofibroma dorsi in which the clinical and ultrasound diagnosis was confirmed by CT and magnetic resonance imaging. The location of the lesions (bilateral in two cases) was typical, in the thoraco-scapular region. When the lesion show typical imaging features and produces no symptoms, as is usually the case; further investigations are probably unnecessary.

[Elastofibroma Dorci;Report of a Case].

Elastofibroma is a relatively rare tumor that occurs commonly at the apex of scapula in elderly people. We report a case of elastofibroma of a female in her seventies. She visited our hospital with complaints of painful mass in her back, which was increasing in size. On the magnetic resonance imaging (MRI),the T1 and the T2-weighted images showed the same signal intensity as the muscle between the right scapula and the intercostal muscles. The internal fat component was cord-like, with high signal intensity. Based on the site of the tumor and characteristic findings on imaging, it was diagnosed as elastofibroma and resection was performed. Pathological findings revealed bundle-like proliferation of fibrous and spherical hyaline substances, together with collagen fibers. The hyaline substance stained in black on Elastica van Gieson staining and was confirmed to be elastic fiber. Thus, it was diagnosed as elastofibroma. The patient is on regular follow-up, with no recurrence after surgery.

Aortic valve-mediated wall shear stress is heterogeneous and predicts regional aortic elastic fiber thinning in bicuspid aortic valve-associated aortopathy.

OBJECTIVES: The objectives of this study were to investigate an association between the magnitude of flow-mediated aortic wall shear stress (WSS) and medial wall histopathology in patients with bicuspid aortic valve (BAV) with aortopathy. METHODS: Patients with BAV (n = 27; 52 ± 15 years; 3 women; proximal thoracic aorta diameter = 4.4 ± 0.7 and 4.6 ± 0.5 cm) who underwent prophylactic aortic resection received preoperative 3-dimensional time-resolved phase-contrast magnetic resonance imaging with 3-dimensional velocity encoding to quantify WSS relative to a population of healthy age- and sex-matched tricuspid aortic valve control participants (n = 20). Quantitative histopathology was conducted on BAV aorta tissue samples resected at surgery (n = 93), and correlation was performed between elastic fiber thickness and in vivo aortic WSS as continuous variables. Validation of elastic fiber thickness was achieved by correlation relative to tissue stiffness determined using biaxial biomechanical testing (n = 22 samples). RESULTS: Elastic fibers were thinner and WSS was higher along the greater curvature compared with other circumferential regions (vs anterior wall: P = .003 and P = .0001, respectively; lesser curvature: both P = .001). Increased regional WSS was associated with decreased elastic fiber thickness (r = -0.25; P = .02). Patient stratification with subanalysis showed an increase in the correlation between WSS and histopathology with aortic valve stenosis (r = -0.36; P = .002) and smaller aortic diameters (<4.5 cm: r = -0.39; P = .03). Elastic fiber thinning was associated with circumferential stiffness (r = -0.41; P = .06). CONCLUSIONS: For patients with BAV, increased aortic valve-mediated WSS is significantly associated with elastic fiber thinning, particularly with aortic valve stenosis and in earlier stages of aortopathy. Elastic fiber thinning correlates with impaired tissue biomechanics. These novel findings further implicate valve-mediated hemodynamics in the progression of BAV aortopathy.

Proliferation of elastic fibres in idiopathic pulmonary fibrosis: a whole-slide image analysis and comparison with pleuroparenchymal fibroelastosis.

AIMS: We occasionally encounter patients with idiopathic pulmonary fibrosis (IPF) who have similar imaging patterns to those of pleuroparenchymal fibroelastosis (PPFE) in the upper lung fields but are not diagnosed as having PPFE clinically. The aim of this study is to identify the clinicopathological features and intrapulmonary distribution of elastic fibres and collagen fibres in these patients. METHODS AND RESULTS: We retrospectively reviewed the medical records of patients with a clinical diagnosis of IPF, and selected consecutive patients who underwent autopsy or pneumonectomy for lung transplantation. Patients with histologically confirmed PPFE were also reviewed for comparison. We quantified the collagen fibres and elastic fibres in each lobe as a percentage of the non-aerated lung area (collagen fibre score and elastic fibre score, respectively) in histological specimens by using whole-slide image analysis, and compared these scores between IPF and PPFE patients. In a total of 55 patients (IPF, 48; PPFE, 7), there were no significant differences in the collagen fibre scores between IPF and PPFE patients. The elastic fibre scores in the upper lobe in PPFE patients were significantly higher than those in IPF patients (23.5 versus 10.3, P = 0.005). However, it is of note that, in 12 of 48 IPF patients, the elastic fibre scores of the upper lobes were above the first quartile of those in PPFE patients. CONCLUSIONS: IPF occasionally shows intense elastosis in the upper lobes, and such cases are histologically indistinguishable from PPFE. There seem to be histologically borderline cases between PPFE and IPF.

Segmentation of elastic fibres in images of vessel wall sections stained with Weigert's resorcin-fuchsin.

BACKGROUND AND OBJECTIVE: The elastic fibres are an essential component of the extracellular matrix in blood vessel walls that allows a long-range of deformability and passive recoil without energy input. The quantitative determination of elastic fibres will provide information on the state of the vascular wall and to determine the role and behaviour of this key structural element in different physiological and pathological vascular processes. METHODS: We present a segmentation method to identify and quantify elastic fibres based on a local threshold technique and some morphological characteristics measured on the segmented objects that facilitate the discrimination between elastic fibres and other image components. The morphological characteristics analysed are the thickness and the length of an object. RESULTS: The segmentation method was evaluated using an image database of vein sections stained with Weigert's resorcin-fuchsin. The performance results are based on a ground truth generated manually resulting in values of sensitivity greater than 80% with the exception in two samples, and specificity values above 90% for all samples. Medical specialists carried out a visual evaluation where the observations indicate a general agreement on the segmentation results' visual quality, and the consistency between the methodology proposed and the subjective observation of the doctors for the evaluation of pathological changes in vessel wall. CONCLUSIONS: The proposed methodology provides more objective measurements than the qualitative methods traditionally used in the histological analysis, with a significant potential for this method to be used as a diagnostic aid for many other vascular pathological conditions and in similar tissues such as skin and mucous membranes.

Impact of stent implantation on endothelial shear stress.

BACKGROUND: Endothelial shear stress (ESS) may play a key role in the pathobiology of stent restenosis (SR). Nevertheless, limited data are available about ESS and its relation to SR. PATIENTS AND METHODS: We enrolled 14 patients who underwent successful percutaneous coronary intervention (PCI) in this study. Three-dimensional (3D) reconstruction of 14 coronary arteries before and after stent implantation was performed. Using computational fluid dynamics, mean ESS was calculated proximally, in tertiles within and distal to the stent, both before and after stent implantation. RESULTS: Stent implantation resulted in a significant ESS decrease in the entire atherosclerotic lesion (1.83 vs. 1.26 Pa, p = 0.02). Regarding the five territories in which the entire lesion was divided, ESS decrease was marginally significant in the area of the second in-stent tertile, and in the area 5 mm distal to the stent, whereas ESS decrease was not significant in the area 5 mm proximal to the stent, and in the area of the first and third in-stent tertile. At 12 months, two patients had SR, but restenosis was not related to ESS decrease. CONCLUSION: ESS decreases after stent implantation but not uniformly, with the major reduction being in the middle tertile of the stent, and distal to the stent. In-stent ESS decrease may create local hemodynamic conditions leading to in-stent and in-segment restenosis.

Histopathology of the filum terminale in children with and without tethered cord syndrome with attention to the elastic tissue within the filum.

PURPOSE: To compare histologically transected fila from pediatric patients with tethered cord syndrome (TCS), with and without a low conus, with controls, focusing on collagenous and elastic tissue. METHODS: Thirty fila from patients with TCS, including 5 where minimal cautery was used prior to filum section, were compared with fila from 27 pediatric cadavers without TCS (controls). Sections of fila were stained with H&E, Masson trichrome and Verhoeff von Gieson elastic stains, and 7 with Gordon and Sweet's reticulin stain. RESULTS: Fila from controls showed loose fibrous connective tissue (FCT) with thin and evenly dispersed elastic fibers (EFs). Reticulin fibers (RFs) were seen in blood vessel walls and nerve twigs. Fat was identified microscopically in 2 fila. All fila from patients with TCS had dense FCT. The EFs were in normal numbers in 17, and focally or diffusely decreased in 13. All 25 patients where the fila were cauterized during resection had thick and coiled EFs. Coiling was not seen when minimal cautery was applied. RFs were seen in blood vessel walls and nerve twigs. Fat was identified in 19 patients. Findings were similar, whether the conus termination was normal or low. CONCLUSION: The fila of all patients with TCS, whether or not the conus was low, showed abnormal FCT. EFs were decreased in 48 % of patients; however, there were thick and coiled EFs in all patients. Coiling of EFs, initially thought to be an abnormality in patients, is considered most likely to be a result of cautery (i.e., artifactual/iatrogenic coiling).

Imaging manifestations of acquired elastopathy resembling pseudoxanthoma elasticum in patients with beta thalassaemia major and sickle cell disease.

Development of an acquired systemic elastopathy resembling pseudoxanthoma elasticum in patients with chronic haemoglobinopathies such as beta thalassaemia major and sickle cell disease is well documented. There is paucity of any comprehensive literature on the radiological manifestations of this entity. This pictorial review aims to describe and illustrate the multi system and multi modality imaging findings of this condition.

Histological Evaluation of Decellularized Skeletal Muscle Tissue Using Two Different Decellularization Agents.

The aim of the present study was to determine effect of two decellularized agents, sodium dodecyl sulphate (SDS) and Triton X-100, to the skeletal muscle tissue. Final scaffold was evaluated by several histological techniques to analyse preservation of essential structures including collagen and elastic fibres, basement membranes, glycosaminoglycans and also to confirm elimination of nuclear and cytoplasmic components which are redundant in effectively prepared decellularized scaffolds. Comparison of tissue scaffolds processed with different detergents proved that SDS is superior to Triton X-100 as it can effectively decellularize muscle tissue.

Elastofibroma dorsi incidentally detected by (18)F-FDG PET/CT imaging.

OBJECTIVE: Elastofibroma dorsi (ED) is a rare pseudotumor of the soft tissues that can also show 18F-fluorodeoxyglucose ((18)F-FDG) uptake on positron emission tomography combined with computed tomography (PET/CT) imaging. The aim of this retrospectively study was to describe the metabolic characteristics of ED incidentally detected by (18)F-FDG PET/CT imaging. MATERIALS AND METHODS: Between November 2009 and August 2013 at our institution, 10,350 consecutive PET/CT examinations were retrospectively investigated. In 176 of these patients, ED was recorded as an incidental finding. Fifty-five of 176 patients also had follow-up scans after chemoradiotherapy. A total of 231 scans with ED in 176 patients were identified. To determine the metabolic activity of ED, the maximum standardized uptake value (SUVmax) was calculated semiquantitatively. For measurement size of ED, the longest axis of transaxial CT images was used. Seven of the 176 patients underwent surgery due to suspected metastases and/or invasion of primary malignancy and/or symptoms or incidental during surgery. RESULTS: The prevalence of ED in our series was 1.7%. The lesions were located in the subscapular region in all patients, except in one case with a lesion in the infrascapular region. A total of 419 ED lesions in 231 scan of 176 patients were evaluated. Mean ± SD SUVmax and long axis values for these 419 lesions were 2.31 ± 0.61 (range 1.0-4.30) and 56.78 ± 17.01 mm (range 19-112 mm), respectively. Of these 176 patients, 141 (80.1%) had bilateral lesions and 35 (19.9%) had unilateral lesions. There were statistically significant differences in the SUVmax and long axis values between the right and left side in the bilateral lesions (p = 0.001). No significant differences in the SUVmax and long axis values of the lesion were found between pre- and posttreatment in the patients with follow-up scans. CONCLUSION: Elastofibroma dorsi located in the scapular region is usually bilateral, asymmetric and with mild or moderate metabolic activity on PET/CT imaging. In addition, the metabolic activity and size of ED remained stable after chemoradiotherapy. Awareness of these metabolic characteristics of ED is important for preventing misinterpretation during (18)F-FDG PET/CT studies.

Breast cancer stromal elastosis is associated with mammography screening detection, low Ki67 expression and favourable prognosis in a population-based study.

BACKGROUND: Mammography screen-detected breast cancers have a better prognosis than predicted from established prognostic markers. A search for additional features that are characteristic for these tumours and their prognosis is needed to reduce overtreatment, a recognized challenge in breast cancer patient management today. Here, we have investigated the occurrence and importance of tumour elastosis. METHODS: We performed a population based retrospective study of breast cancers detected in the Norwegian Breast Cancer Screening Programme in Vestfold County during 2004-2009. In total, 197 invasive screen-detected cancers and 75 interval cancers in patients aged 50-69 years were compared with regard to standard clinico-pathological parameters and tumour shape, as well as ER, PR, HER2 and Ki67 expression. In particular, the presence of elastotic material in tumours was graded on a 4-tiered scale (score 0-3). RESULTS: Screen-detected cancers had a significantly higher content of stromal elastosis than interval cancers (p < 0.001). High content of elastosis (score 3) correlated strongly with stellate tumour shape, low histological grade, and ER+/HER2- status. Further, high elastosis score was significantly associated with lower Ki67 expression. In survival analyses, cases with high elastosis demonstrated increased recurrence free (p = 0.03) and disease-specific survival (p = 0.11) compared to cases with low elastosis. CONCLUSION: There is a strong correlation between the presence of tumour elastosis, stellate tumour shape and mammography detection of breast cancers. To our knowledge, this is the first time elastosis has been studied in relation to breast cancer detection method. Presence of elastosis is associated with low tumour cell proliferation (Ki67) and a good prognosis. VIRTUAL SLIDES: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/13000_2014_230.

Effect of depth on shear-wave elastography estimated in the internal and external cervical os during pregnancy.

AIM: To investigate the effect of depth on cervical shear-wave elastography. METHODS: Shear-wave elastography was applied to estimate the velocity of propagation of the acoustic force impulse (shear wave) in the cervix of 154 pregnant women at 11-36 weeks of gestation. Shear-wave speed (SWS) was evaluated in cross-sectional views of the internal and external cervical os in five regions of interest: anterior, posterior, lateral right, lateral left, and endocervix. Distance from the center of the ultrasound (US) transducer to the center of each region of interest was registered. RESULTS: In all regions, SWS decreased significantly with gestational age (P=0.006). In the internal os, SWS was similar among the anterior, posterior, and lateral regions and lower in the endocervix. In the external os, the endocervix and anterior regions showed similar SWS values, lower than those from the posterior and lateral regions. In the endocervix, these differences remained significant after adjustment for depth, gestational age, and cervical length. SWS estimations in all regions of the internal os were higher than those of the external os, suggesting denser tissue. CONCLUSION: Depth from the US probe to different regions in the cervix did not significantly affect the SWS estimations.