Wide-field Mueller matrix polarimetry for spectral characterization of basic biological tissues: Muscle, fat, connective tissue, and skin

This study investigates the polarimetric properties of skin, skeletal muscle, connective tissue, and fat using Mueller matrix imaging. It aims to compare the polarimetric characteristics of these tissues and explore how they evolve with wavelength. Additionally, the temporal evolution of certain tissues during meat aging is studied, providing insights into the dynamic behavior of polarimetric properties over time. The research employs back-scattering configuration and the differential decomposition analysis method of Mueller matrix images. Both in-vivo and ex-vivo experiments were conducted using a consistent instrument setup to ensure reliable analysis. The results reveal wavelength-dependent variations in tissue properties, including an increase in depolarization with wavelength. Significant differences in the polarimetric characteristics of meat tissues, particularly for skeletal muscle, are observed. Over a 24-h period, intensity, diattenuation, and retardation experience alterations, being the decreased retardation in skeletal muscle and the increased retardation in fat the most notable ones.

Ultrasound measurement of subsynovial connective tissue thickness in the carpal tunnel: An intrarater/interrater reliability and agreement study

OBJECTIVES

Non-inflammatory thickening of the subsynovial connective tissue (SSCT) in the carpal tunnel is commonly found in subjects with carpal tunnel syndrome (CTS), and quantification may shed light on CTS pathogenesis. To date, information on the reliability of ultrasound quantification of SSCT is scarce. Therefore, we investigated intrarater and interrater reliability/agreement for ultrasound quantification of SSCT thickness in subjects with and without CTS, and predictors for tissue thickness.

MATERIAL AND METHODS

Two investigators quantified SSCT thickness and thickness ratio on ultrasound in 16 healthy subjects (age, 24-65 years; 16 left/14 right wrists) and 17 subjects with CTS (age, 37-83 years; 14 left/14 right wrists). Intra- and inter-rater reliability/agreement were assessed on intraclass correlation coefficients, standard error of measurement and minimal detectable change. A mixed-effects model was used to evaluate potential predictors for SSCT thickness.

RESULTS

Intra- and inter-rater reliability analysis showed good to excellent intraclass correlation coefficients in both groups, ranging from 0.772 to 0.965. The maximum percentage standard error of measurement was 8%. The maximum minimal detectable change was 14% within raters, and 20% between raters. Both intra- and inter-rater reliability values for thickness ratio were poor. Presence of CTS (ß = 0.180; p = 0.015) correlated positively with SSCT thickness.

CONCLUSIONS

Ultrasound is a reliable method for quantification of SSCT thickness, but not for thickness ratio. Presence of CTS correlates positively with SSCT thickness.

Relative motion between the flexor digitorum superficialis tendon and subsynovial connective tissue is time dependent

The subsynovial connective tissue is an integral component of flexor tendon gliding in the carpal tunnel, which is strained during longitudinal tendon displacement. We tested the effects of repetition frequency and finger load on flexor tendon function throughout active finger movement. Eleven participants performed metacarpophalangeal joint flexion/extension of the long finger cyclically at three repetition frequencies (0.75, 1.00, 1.25 Hz) and two finger loads (3.5, 7 N). Relative displacement between the flexor digitorum superficialis tendon and subsynovial connective tissue was assessed as the shear-strain index with color ultrasound throughout the entire time history of finger flexion and extension. In addition, long finger joint angles were measured with electrogoniometry while flexor digitorum superficialis and extensor digitorum muscle activities were measured with fine-wire electromyography to characterize the finger movements. The shear-strain index increased with greater finger flexion (p = 0.001), representing higher relative displacement between tendon and subsynovial connective tissue; however, no changes were observed throughout finger extension. The shear-strain index also increased with higher repetition frequencies (p = 0.013) and finger loads (p = 0.029), further modulating time-dependent effects during finger flexion versus extension. Using ultrasound, we characterized the time-dependent response of the shear-strain index, in vivo, providing valuable data on flexor tendon function during active finger movement. Our results infer greater subsynovial connective tissue strain and shear during repetitive and forceful finger movements. Future research characterizing time-dependent effects in carpal tunnel syndrome patients may further elucidate the relations between subsynovial connective tissue function, damage, and carpal tunnel syndrome.

Quantitative in vivo micro-computed tomography for monitoring disease activity and treatment response in a collagen-induced arthritis mouse model

A painful, chronic condition, Rheumatoid Arthritis, is marked by bone erosion and soft tissue swelling at the joint. As treatments are investigated in pre-clinical models, characterizing disease progression is integral to assessing treatment efficacy. Here, in vivo and ex vivo micro-computed tomography (µCT) are used in parallel with traditional caliper score measurement to quantify physiological changes in the tarsal region in a murine, collagen-induced arthritis model. In vivo imaging methods, which are validated here through comparison to ex vivo and caliper methods, afford longitudinal analysis of both bone and soft tissue through a single image acquisition. This method removes the subjectivity of swelling quantification which is inherently associated with traditional caliper measurements. Histopathology offers an additional assessment of bone erosion and inflammation by providing a microscopic characterization of disease activity. In comparison to untreated animals, daily prednisolone (glucocorticoid) treatment is shown to restore bone volume, as reflected through in vivo and ex vivo µCT images, as well as histopathology. Prednisolone-associated reduction in inflammation is shown through in vivo µCT soft tissue volume measurements, paw caliper measurements, and histopathology. The findings reported here provide a comprehensive validation of in vivo µCT with a sensitivity that enables characterization of pre-clinical disease assessment in response to treatment in a murine, collagen-induced arthritis model.

Modeling of iterative time-reversed ultrasonically encoded optical focusing in a reflection mode

Time-reversed ultrasonically-encoded (TRUE) optical focusing is a promising technique to realize deep-tissue optical focusing by employing ultrasonic guide stars. However, the sizes of the ultrasound-induced optical focus are determined by the wavelengths of the ultrasound, which are typically tens of microns. To satisfy the need for high-resolution imaging and manipulation, iterative TRUE (iTRUE) was proposed to break this limit by triggering repeated interactions between light and ultrasound and compressing the optical focus. However, even for the best result reported to date, the resolutions along the ultrasound axial and lateral direction were merely improved by only 2-fold to 3-fold. This observation leads to doubt whether iTRUE can be effective in reducing the size of the optical focus. In this work, we address this issue by developing a physical model to investigate iTRUE in a reflection mode numerically. Our numerical results show that, under the influence of shot noises, iTRUE can reduce the optical focus to a single speckle within a finite number of iterations. This model also allows numerical investigations of iTRUE in detail. Quantitatively, based on the parameters set, we show that the optical focus can be reduced to a size of 1.6 µm and a peak-to-background ratio over 10⁴ can be realized. It is also shown that iTRUE cannot significantly advance the focusing depth. We anticipate that this work can serve as useful guidance for optimizing iTRUE system for future biomedical applications, including deep-tissue optical imaging, laser surgery, and optogenetics.

Carpal tunnel syndrome treatment and the subsequent alterations in tendon and connective tissue dynamics

BACKGROUND

Carpal tunnel syndrome patients demonstrate diminished motion of the median nerve and fibrotic changes in the subsynovial connective tissue within the carpal tunnel. Currently, there are few prognostic factors to help predict the outcome of commonly performed treatments including surgical carpal tunnel release and corticosteroid injections. This study aimed to non-invasively assess the changes in the dynamic response of the subsynovial tissue relative to tendon motion after the intervention and to correlate this with disease severity.

METHODS

A total of 145 patients with carpal tunnel syndrome were recruited into this study. Clinical and demographic data, electrophysiological severity and dynamic ultrasound images were collected before and after treatment, either by injection or surgery. The relative motion of the subsynovial tissue with the underlying middle finger flexor digitorum superficialis tendon was measured using a speckle tracking algorithm and was expressed as a shear index (SI). Baseline and follow-up data, the association between change in SI and severity, and the role of treatment modality were analyzed and statistically compared.

FINDINGS

Overall, there was a significant increase (more relative motion) after treatment in the mean shear index from 79.9% (±15.4% SD) to 82.9% (±14.8% SD) (p = 0.03). Secondary analyses showed that this change was mostly present in those with mild disease severity undergoing surgery (p = 0.01).

INTERPRETATION

This study shows that the relative subsynovial tissue movement increases in patients after intervention. The present study lays a foundation for future studies to non-invasively assess the role of carpal tunnel dynamics in response to treatment.

Multiplexed histology analyses for the phenotypic and spatial characterization of human innate lymphoid cells

Innate lymphoid cells (ILCs) emerge in the last few years as important regulators of immune responses and biological processes. Although ILCs are mainly known as tissue-resident cells, their precise localization and interactions with the microenvironment are still unclear. Here we combine a multiplexed immunofluorescence technique and a customized computational, open-source analysis pipeline to unambiguously identify CD127+ ILCs in situ and characterize these cells and their microenvironments. Moreover, we reveal the transcription factor IRF4 as a marker for tonsillar ILC3, and identify conserved stromal landmarks characteristic for ILC localization. We also show that CD127+ ILCs share tissue niches with plasma cells in the tonsil. Our works thus provide a platform for multiparametric histological analysis of ILCs to improve our understanding of ILC biology.

Quantitative analysis of gliding between subcutaneous tissue and the vastus lateralis - Influence of the dense connective tissue of the myofascia

INTRODUCTION

The thickness of connective tissue has been shown to be associated with pain (Stecco et al., 2014). However, the relationship between fascial thickness and gliding remains unclear. In addition, the influence between gliding and the motion rhythm and limb position isn't clear.

METHOD

A therapist moved patient's lower leg at one of two constant rhythms (40 or 60bpm). Gliding of both the vastus lateralis (VL) muscle and subcutaneous (SC) tissue were recorded during knee motion using ultrasonography. Particle image velocimetry analysis software was adapted to create the flow velocity from echo imaging. Gliding was calculated using a coefficient of correlation from each flow velocity. Myofascial thickness and SC were measured using Image-J. The ratios of the loose connective tissue (LCT) and dense connective tissue (DCT) thickness to the total myofascial thickness were calculated. Repeated-measures two-way ANOVA was used to compare the two motion rhythms and three positions, with stepwise multiple regression analysis to analyze the predictors that influenced the gliding coefficient at each rhythm.

RESULTS

Repeated-measures two-way ANOVA showed that the effect of rhythm was statistically significant, but the effect of position was not. At a 40 bpm rhythm, stepwise multiple regression analysis selected SC thickness and DCT thickness as significant factors, while at a 60 bpm rhythm, SC thickness and DCT ratio were selected.

CONCLUSION

This study revealed that increased thickness of DCT of the myofascia and SC resulted in decreased gliding between the VL and SC, demonstrating that gliding is related to fascial thickness. Motion rhythm influences gliding between tissues.

Relative Motion of the Connective Tissue in Carpal Tunnel Syndrome: The Relation with Disease Severity and Clinical Outcome

Excursion of the median nerve and the surrounding subsynovial connective tissue (SSCT) is diminished in patients with carpal tunnel syndrome (CTS). This study sought to determine if SSCT excursion could be utilized to predict surgical outcome. Idiopathic CTS patients were reviewed with ultrasound and electrodiagnostic tests at baseline. A speckle tracking algorithm was used to determine SSCT relative to tendon motion (shear index). Analysis of variance tests were used to compare SSCT motion with disease severity at baseline. Adjusted linear regressions were used to test the association with patient-reported outcome. A total of 90 CTS patients were analyzed and found to have an average shear index of 79% (95% confidence interval: 76.3%-81.6%). SSCT motion was lower in CTS patients with increasing electrophysiological severity (p = 0.0475). There was no significant association of pre-operative SSCT motion with symptomatic improvement (p = 0.268). Overall, SSCT motion is decreased in CTS patients, but exhibits limited correlation with clinical severity.

Ultrasound Evaluation of Pediatric Orthopaedic Patients

Ultrasonography is a valuable tool that can be used in many capacities to evaluate and treat pediatric orthopaedic patient. It has the capability to depict bone, cartilaginous and soft-tissue structures, and provide dynamic information. This technique can be readily applied to a wide range of pediatric conditions, including developmental dysplasia of the hip, congenital limb deficiencies, fracture management, joint effusions, and many other musculoskeletal pathologies. There are many benefits of implementing ultrasonography as a regular tool. It is readily accessible at most centers, and information can be quickly obtained in a minimally invasive way, which limits the need for radiation exposure. Ultrasonography is a safe and reliable tool that pediatric orthopaedic surgeons can incorporate into the diagnosis and management of a broad spectrum of pathology.

Subsynovial connective tissue thickness in carpal tunnel syndrome: A systematic review

BACKGROUND

Non-inflammatory thickening of the subsynovial connective tissue is a common histological finding in carpal tunnel syndrome. This subsynovial connective tissue thickening may precede changes in electrodiagnostic testing. Therefore, measuring subsynovial connective tissue thickness may help in detecting early changes in carpal tunnel syndrome.

METHODS

To provide an overview of subsynovial connective tissue thickness characteristics in subjects with and without carpal tunnel syndrome, a systematic review of articles, assessing human subsynovial connective tissue, was performed using MEDLINE, CENTRAL and EMBASE.

FINDINGS

Seven studies were included for qualitative analysis. Measurements were done ex vivo (laser (n = 3), photographic (n = 1), micrometric (n = 1)) and in vivo (ultrasound (n = 3)). All four case-control studies showed a significant difference in subsynovial connective tissue thickness between subjects with and without carpal tunnel syndrome. One study showed good correlation between ultrasound and anatomical measurements. No correlation was found between subsynovial connective tissue thickness and symptom duration, electrodiagnostic changes, age and sex.

INTERPRETATION

Subsynovial connective tissue thickness may be a valuable aid in diagnosing carpal tunnel syndrome. No factors influencing subsynovial connective tissue thickness are identified, although they are not well investigated.

Investigation of light delivery geometries for photoacoustic applications using Monte Carlo simulations with multiple wavelengths, tissue types, and species characteristics

Combined ultrasound and photoacoustic imaging systems are being developed for biomedical and clinical applications. One common probe configuration is to use a linear transducer array with external light delivery to produce coregistered ultrasound and photoacoustic images. The diagnostic capability of these systems is dependent on the effectiveness of light delivery to the imaging target. We use Monte Carlo modeling to investigate the optimal design geometry of an integrated probe. Simulations are conducted with multiple tissue compositions and wavelengths. The effect of a skin layer with the thickness of a mouse or a human is also considered. The model was validated using a tissue-mimicking gelatin phantom and corresponding Monte Carlo simulations. The optimal illumination angle is shallower with human skin thickness, whereas intermediate angles are ideal with mouse skin thickness. The effect of skin thickness explains differences in the results of prior work. The simulations also indicate that even with identical hardware and imaging parameters, light delivery will be up to 3  ×   smaller in humans than in mice, due to the increased scattering from thicker skin. Our findings have clear implications for the many researchers using mice to test and develop imaging methods for clinical translation.

Recent advances in MRI of the head and neck, skull base and cranial nerves: new and evolving sequences, analyses and clinical applications

MRI is an invaluable diagnostic tool in the investigation and management of patients with pathology of the head and neck. However, numerous technical challenges exist, owing to a combination of fine anatomical detail, complex geometry (that is subject to frequent motion) and susceptibility effects from both endogenous structures and exogenous implants. Over recent years, there have been rapid developments in several aspects of head and neck imaging including higher resolution, isotropic 3D sequences, diffusion-weighted and diffusion-tensor imaging as well as permeability and perfusion imaging. These have led to improvements in anatomic, dynamic and functional imaging. Further developments using contrast-enhanced 3D FLAIR for the delineation of endolymphatic structures and black bone imaging for osseous structures are opening new diagnostic avenues. Furthermore, technical advances in compressed sensing and metal artefact reduction have the capacity to improve imaging speed and quality, respectively. This review explores novel and evolving MRI sequences that can be employed to evaluate diseases of the head and neck, including the skull base.

Ultrasound Features of Ankle Retinacula: Normal Appearance and Pathologic Findings

Disorders of retinacula are frequent in acute and repetitive microtrauma of the ankle. Ultrasound (US), thanks to its spatial resolution and dynamic capabilities, is routinely used in the evaluation of the posttraumatic ankle for accurate delineation of ligaments and tendons. In addition, US can provide a depiction of normal retinacula and a detailed assessment of their pathologic changes. An accurate US assessment of ankle retinacula is helpful in choosing the proper treatment. In this pictorial essay, we briefly review the normal anatomy of ankle retinacula, describe their normal US appearance, and present a wide range of US pathologic abnormalities.

The myodural bridge complex defined as a new functional structure

PURPOSE

The connective tissue between suboccipital muscles and the cervical spinal dura mater (SDM) is known as the myodural bridge (MDB). However, the adjacent relationship of the different connective tissue fibers that form the MDB remains unclear. This information will be highly useful in exploring the function of the MDB.

METHODS

The adjacent relationship of different connective tissue fibers of MDB was demonstrated based upon three-dimensional visualization model, P45 plastinated slices and histological sections of human MDB.

RESULTS

We found that the MDB originating from the rectus capitis posterior minor muscle (RCPmi), rectus capitis posterior major muscle (RCPma) and obliquus capitis inferior muscle (OCI) in the suboccipital region coexists. Part of the MDB fibers originate from the ventral aspect of the RCPmi and, together with that from the cranial segment of the RCPma, pass through the posterior atlanto-occipital interspace (PAOiS) and enter into the posterior aspect of the upper cervical SDM. Also, part of the MDB fibers originate from the dorsal aspect of the RCPmi, the ventral aspect of the caudal segment of the RCPma, and the ventral aspect of the medial segment of the OCI, enter the central part of the posterior atlanto-axial interspace (PAAiS) and fuse with the vertebral dura ligament (VDL), which connects with the cervical SDM.

CONCLUSIONS

Our findings prove that the MDB exists as a complex structure which we termed the 'myodural bridge complex' (MDBC). In the process of head movement, tensile forces could be transferred possibly and effectively by means of the MDBC. The concept of MDBC will be beneficial in the overall exploration of the function of the MDB.

A new and simplified comprehensive ultrasound protocol of haemophilic joints: the Universal Simplified Ultrasound (US-US) protocol

AIM

To present a new protocol to optimise ultrasound (US) assessment of haemophilic arthropathy.

MATERIALS AND METHODS

Ultrasound of haemophilic arthropathy joints was performed using three different ultrasound protocols, namely, the Toronto-Vellore Comprehensive Ultrasound (TVC-US) protocol, the Haemophilia Early Arthropathy Detection with Ultrasound (HEAD-US), and the newly developed Universal Simplified Ultrasound (US-US) protocol. Synovial hypertrophy, haemosiderin deposition, effusion, erosion, and cartilage loss were evaluated in 20 joints. The reliability and diagnostic efficiency of these protocols was compared using magnetic resonance imaging (MRI).

RESULTS

The correlation between the TVC-US and US-US protocols for synovial hypertrophy was excellent: kappa significance (KS) was 1, but was substantial (KS=0.65) with the HEAD-US protocol. For effusion, both the TVC-US and the HEAD-US protocols had substantial correlation with the US-US protocol (KS=0.7 and 0.6 respectively). The correlation for erosion and cartilage loss was excellent between the TVC-US and the US-US with MRI (KS=1), but poor (KS=0) with the HEAD-US protocol. The US-US protocol also had good interobserver agreement (KS=1).

CONCLUSION

The accuracy of the US-US protocol is comparable to the TVC-US protocol and MRI and is superior to the HEAD-US protocol in the assessment of haemophilic arthropathy.

Assessment of Palatal Mucosal Wound Healing Following Connective-Tissue Harvesting by Laser Speckle Contrast Imaging: An Observational Case Series Study

Postoperative complications may occur during the healing of palatal donor sites due to disturbed blood circulation of palatal tissues. Therefore in this study, blood flow was measured by Laser Speckle Contrast Imaging (LSCI) in seven patients after connective-tissue harvesting. The slope in blood-flow elevation within the first 3 days as well as time needed for maximum reperfusion were calculated. Each surgical site was assessed by clinical examination on day 3. In donor sites with secondary-intention wound healing, postoperative blood flow was elevated with significant delay compared to the surrounding tissues and to the primarily healed wound. Reperfusion time and healing score were strongly correlated (r = 0.87, P < .001), as were the slope and clinical rank (r = -0.85, P < .001). LSCI proved to be an objective method to assess individual wound-healing time and to predict the quality of wound healing.

Collagen networks determine viscoelastic properties of connective tissues yet do not hinder diffusion of the aqueous solvent

Collagen accounts for the major extracellular matrix (ECM) component in many tissues and provides mechanical support for cells. Magnetic Resonance (MR) Imaging, MR based diffusion measurements and MR Elastography (MRE) are considered sensitive to the microstructure of tissues including collagen networks of the ECM. However, little is known whether water diffusion interacts with viscoelastic properties of tissues. This study combines highfield MR based diffusion measurements, novel compact tabletop MRE and confocal microscopy in collagen networks of different cross-linking states (untreated collagen gels versus additional treatment with glutaraldehyde). The consistency of bulk rheology and MRE within a wide dynamic range is demonstrated in heparin gels, a viscoelastic standard for MRE. Additional crosslinking of collagen led to an 8-fold increased storage modulus, a 4-fold increased loss modulus and a significantly decreased power law exponent, describing multi-relaxational behavior, corresponding to a pronounced transition from viscous-soft to elastic-rigid properties. Collagen network changes were not detectable by MR based diffusion measurements and microscopy which are sensitive to the micrometer scale. The MRE-measured shear modulus is sensitive to collagen fiber interactions which take place on the intrafiber level such as fiber stiffness. The insensitivity of MR based diffusion measurements to collagen hydrogels of different cross-linking states alludes that congeneric collagen structures in connective tissues do not hinder extracellular diffusive water transport. Furthermore, the glutaraldehyde induced rigorous changes in viscoelastic properties indicate that intrafibrillar dissipation is the dominant mode of viscous dissipation in collagen-dominated connective tissue.

Simulation of the Second-Harmonic Ultrasound Field in Heterogeneous Soft Tissue Using a Mixed-Domain Method

A mixed-domain method (MDM) dubbed frequency-specific MDM (FSMDM) is introduced for the simulation of the second-harmonic ultrasound field in weakly heterogeneous media. The governing equation for the second harmonics is derived based on the quasi-linear theory. The speed of sound, nonlinear coefficient, and attenuation coefficient are all spatially varying functions in the equation. The fundamental frequency pressure field is first solved by the FSMDM and it is subsequently used as the source term for the second-harmonics equation. This equation can be again solved by the FSMDM to rapidly obtain the second-harmonic pressure field. Five 2-D cases, including one with a realistic human tissue map, are studied to systematically verify the proposed method. Results from the previously developed transient MDM are used as the benchmark solutions. Comparisons show that the two methods give similar results for all cases. More importantly, the FSMDM has a crucial advantage over the transient MDM in that it can be two orders of magnitude faster.

Reliability of ultrasound speckle tracking with singular value decomposition for quantifying displacement in the carpal tunnel

Inhibited movement patterns of carpal tunnel structures have been found in carpal tunnel syndrome (CTS) patients. Motion analysis on ultrasound images allows us to non-invasively study the (relative) movement of carpal tunnel structures and recently a speckle tracking method using singular value decomposition (SVD) has been proposed to optimize this tracking. This study aims to assess the reliability of longitudinal speckle tracking with SVD in both healthy volunteers and patients with CTS. Images from sixteen healthy volunteers and twenty-two CTS patients were used. Ultrasound clips of the third superficial flexor tendon and surrounding subsynovial connective tissue (SSCT) were acquired during finger flexion-extension. A custom made tracking algorithm was used for the analysis. Intra-class correlation coefficients (ICCs) were calculated using a single measure, two-way random model with absolute agreement and Bland-Altman plots were added for graphical representation. ICC values varied between 0.73 and 0.95 in the control group and 0.66-0.98 in the CTS patients, with the majority of the results classified as good to excellent. Tendon tracking showed higher reliability values compared to the SSCT, but values between the control and CTS groups were comparable. Speckle tracking with SVD can reliably be used to analyze longitudinal movement of anatomical structures with different sizes and compositions within the context of the carpal tunnel in both a healthy as well as a pathological state. Based on these results, this technique also holds relevant potential for areas where ultrasound based dynamic imaging requires quantification of motion.

In vivo characterization of connective tissue remodeling using infrared photoacoustic spectra

Premature cervical remodeling is a critical precursor of spontaneous preterm birth, and the remodeling process is characterized by an increase in tissue hydration. Nevertheless, current clinical measurements of cervical remodeling are subjective and detect only late events, such as cervical effacement and dilation. Here, we present a photoacoustic endoscope that can quantify tissue hydration by measuring near-infrared cervical spectra. We quantify the water contents of tissue-mimicking hydrogel phantoms as an analog of cervical connective tissue. Applying this method to pregnant women in vivo, we observed an increase in the water content of the cervix throughout pregnancy. The application of this technique in maternal healthcare may advance our understanding of cervical remodeling and provide a sensitive method for predicting preterm birth.

Increasing soft tissue thickness does not affect trabecular bone score reproducibility: a phantom study

PURPOSE

Trabecular Bone Score (TBS) provides an indirect score of trabecular microarchitecture from lumbar spine (LS) dual energy X-ray absorptiometry. Increasing soft tissue thickness artifactually reduces TBS values; we evaluated the effect of a fictitious increase of soft tissue thickness on TBS and bone mineral density (BMD) reproducibility on a phantom model.

METHODS

A Hologic spine phantom was scanned with a QDR-Discovery W Hologic densitometer. Fresh pork rind layers of 5 mm were used to simulate the in-vivo soft tissues. For each scan mode (fast array [FA], array, high definition [HD]), 25 scans were consecutively performed without phantom repositioning, at 0 (no layers), 1 cm, 3 cm, and 6 cm of thickness. BMD and TBS reproducibility was calculated as the complement to 100% of least significant change.

RESULTS

Both BMD and TBS reproducibility slightly decreased with increasing soft tissue; this difference was statistically significant only for BMD using HD modality (reproducibility decreased from 99.4% at baseline to 98.4% at 6-cm of thickness). TBS reproducibility was slightly lower compared to that of BMD, and ranged between 98.8% (array, 0 cm) and 97.4% (FA, 6 cm). Without taking into account manufacturer BMI optimization, we found a progressive decrease of TBS mean values with increasing soft tissue thickness. The highest TBS difference between baseline scan and 6 cm was -0.179 (-14.27%) using HD.

CONCLUSIONS

Despite being slightly lower than that of BMD, TBS reproducibility was not affected up to 6 cm of increasing soft tissue thickness, and was even less influenced by fat than BMD reproducibility.

Intraoperative hyperspectral determination of human tissue properties

We address the automatic differentiation of human tissue using multispectral imaging with promising potential for automatic visualization during surgery. Currently, tissue types have to be continuously differentiated based on the surgeon's knowledge only. Further, automatic methods based on optical in vivo properties of human tissue do not yet exist, as these properties have not been sufficiently examined. To overcome this, we developed a hyperspectral camera setup to monitor the different optical behavior of tissue types in vivo. The aim of this work is to collect and analyze these behaviors to open up optical opportunities during surgery. Our setup uses a digital camera and several bandpass filters in front of the light source to illuminate different tissue types with 16 specific wavelength ranges. We analyzed the different intensities of eight healthy tissue types over the visible spectrum (400 to 700 nm). Using our setup and sophisticated postprocessing in order to handle motion during capturing, we are able to find tissue characteristics not visible for the human eye to differentiate tissue types in the 16-dimensional wavelength domain. Our analysis shows that this approach has the potential to support the surgeon's decisions during treatment.

Evaluation of tissue changes following intramuscular infiltration of lidocaine in rainbow trout Oncorhynchus mykiss

Rainbow trout Oncorhynchus mykiss were infiltrated with either saline or lidocaine adjacent to the dorsal fin to assess histopathological changes. Infiltration was done as if it were being used as a local anaesthetic. Tissue lesions and associated tissue healing were examined over a period of 30 days. Most changes occurred at the cranial site of where the solution was first infiltrated. The infiltration of a dose of 10 mg kg^-1 of lidocaine appears to have damaged the skeletal muscle and connective tissues more than a similar volume of saline, especially during the first 15 days. The primary changes included haemorrhage, inflammation and muscle degeneration and necrosis. By day 30 post-infiltration inflammatory lesions were either nearly or completely absent, signs of myofibre regeneration were noted in only one fish. This experiment shows local anaesthetics and saline can produce localized tissue damage, especially during the first 2 weeks post infiltration. Care should be taken to allow the fish to heal for at least 30 days and probably more, no matter the solution administered, especially if giving repeated injections or infiltrations at the same site.

Microstructural models for diffusion MRI in breast cancer and surrounding stroma: an ex vivo study

The diffusion signal in breast tissue has primarily been modelled using apparent diffusion coefficient (ADC), intravoxel incoherent motion (IVIM) and diffusion tensor (DT) models, which may be too simplistic to describe the underlying tissue microstructure. Formalin-fixed breast cancer samples were scanned using a wide range of gradient strengths, durations, separations and orientations. A variety of one- and two-compartment models were tested to determine which best described the data. Models with restricted diffusion components and anisotropy were selected in most cancerous regions and there were no regions in which conventional ADC or DT models were selected. Maps of ADC generally related to cellularity on histology, but maps of parameters from more complex models suggest that both overall cell volume fraction and individual cell size can contribute to the diffusion signal, affecting the specificity of ADC to the tissue microstructure. The areas of coherence in diffusion anisotropy images were small, approximately 1 mm, but the orientation corresponded to stromal orientation patterns on histology.

In vivo ultrasonic attenuation in cetacean soft tissues

In vivo ultrasonic attenuation was estimated for extracranial soft tissues of two Tursiops truncatus and one Delphinapterus leucas. Backscatter data was non-invasively collected as part of routine health-based ultrasound examinations using a transducer operating in the 1.6-3.7 MHz frequency range. Data collected over the proximal mandible and temporal regions was processed to yield attenuation estimates using a reference tissue phantom whose properties had been independently determined. The estimated attenuations were at the low end of the range of literature-reported values for mammalian fatty and connective tissues. A companion model-based analysis quantified errors arising from tissue composition and sound speed uncertainties.

Probing multi-scale mechanical damage in connective tissues using X-ray diffraction

The accumulation of microstructural collagen damage following repetitive loading is linked to painful and debilitating tendon injuries. As a hierarchical, semi-crystalline material, collagen mechanics can be studied using X-ray diffraction. The aim of the study was to describe multi-structural changes in tendon collagen following controlled plastic damage (5% permanent strain). We used small angle X-ray scattering (SAXS) to interrogate the spacing of collagen molecules within a fibril, and wide angle X-ray scattering (WAXS) to measure molecular strains under macroscopic loading. Simultaneous recordings of SAXS and WAXS patterns, together with whole-tissue strain in physiologically hydrated rat-tail tendons were made during increments of in situ tensile loading. Results showed that while tissue level modulus was unchanged, fibril modulus decreased significantly, and molecular modulus significantly increased. Further, analysis of higher order SAXS peaks suggested structural changes in the gap and overlap regions, possibly localising the damage to molecular cross-links. Our results provide new insight into the fundamental damage processes at work in collagenous tissues and point to new directions for their mitigation and repair.

STATEMENT OF SIGNIFICANCE

This article reports the first in situ loading synchrotron studies on mechanical damage in collagenous tissues. We provide new insight into the nano- and micro-structural mechanisms of damage processes. Pre-damaged tendons showed differential alteration of moduli at macro, micro and nano-scales as measured using X-ray scattering techniques. Detailed analysis of higher order diffraction peaks suggested damage is localised to molecular cross-links. The results are consistent with previous X-ray scattering studies of tendons and also with recent thermal stability studies on damaged material. Detailed understanding of damage mechanisms is essential in the development of new therapies promoting tissue repair.

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).

Development of a Soft Tissue Elastography Robotic Arm (STiERA)

High fidelity surgical simulations must rely upon accurate soft tissue models to ensure realism of the simulations. Simulating multi-layer tissue becomes increasingly complex due to the specific mechanical properties of each individual layer. We have developed a Soft Tissue Elastography Robotic Arm (STiERA) system capable of identifying layer specific properties of multi-layer constructs while maintaining the integrity of each layer. The system was validated using tissue mimicking agar gel phantoms and showed great promise by identifying the layer specific properties with accuracy of greater than 80% when compared to known ground truth values from a commercial material testing system.

[Orbital radiographic anatomy. Part 2. Orbital soft tissue contents]

OBJECTIVE

to study the characteristics of orbital soft tissues in health.

MATERIAL AND METHODS

Computed tomography scans of 210 individuals (266 orbits) with no orbital abnormality were examined.

RESULTS

The paper presents the volumetric characteristics and parameters of the soft tissue density of the orbit and its apex (extraocular muscles, retrobulbar fat, optic nerve, lacrimal gland, eye, and vitreous body) in health. The internal surgical space fat at the orbital apex is estimated to be 75.35 and 73.83% of the total volume at the apex in men and women, respectively. The paper shows that individual asymmetry of orbital fat volumes in health is encountered in 47.61% of the men and in 51.42% of the women and ranges from 0.5 to 2.0 cm³.

CONCLUSION

The volumes of orbital soft tissues in health are statistically significant different in the men and in the women. The asymmetry of the mean orbital soft tissue volumes in health is within the limits of statistical error.

Acoustic property reconstruction of a pygmy sperm whale (Kogia breviceps) forehead based on computed tomography imaging

Computed tomography (CT) imaging and sound experimental measurements were used to reconstruct the acoustic properties (density, velocity, and impedance) of the forehead tissues of a deceased pygmy sperm whale (Kogia breviceps). The forehead was segmented along the body axis and sectioned into cross section slices, which were further cut into sample pieces for measurements. Hounsfield units (HUs) of the corresponding measured pieces were obtained from CT scans, and regression analyses were conducted to investigate the linear relationships between the tissues' HUs and velocity, and HUs and density. The distributions of the acoustic properties of the head at axial, coronal, and sagittal cross sections were reconstructed, revealing that the nasal passage system was asymmetric and the cornucopia-shaped spermaceti organ was in the right nasal passage, surrounded by tissues and airsacs. A distinct dense theca was discovered in the posterior-dorsal area of the melon, which was characterized by low velocity in the inner core and high velocity in the outer region. Statistical analyses revealed significant differences in density, velocity, and acoustic impedance between all four structures, melon, spermaceti organ, muscle, and connective tissue (p < 0.001). The obtained acoustic properties of the forehead tissues provide important information for understanding the species' bioacoustic characteristics.

Pathological changes in the subsynovial connective tissue increase with self-reported carpal tunnel syndrome symptoms

BACKGROUND

Fibrosis and thickening of the subysnovial connective tissue are the most common pathological findings in carpal tunnel syndrome. The relationship between subsynovial connective tissue characteristics and self-reported carpal tunnel syndrome symptoms was assessed.

METHODS

Symptoms were characterized using the Boston Carpal Tunnel Questionnaire and Katz hand diagram in twenty-two participants (11 with symptoms, 11 with no symptoms). Using ultrasound, the thickness of the subsynovial connective tissue was measured using a thickness ratio (subsynovial thickness/tendon thickness) and gliding function was assessed using a shear strain index ((Displacement(tendon)-Displacement(subsynovial))/Displacement(tendon)x 100). For gliding function, participants performed 10 repeated flexion-extension cycles of the middle finger at a rate of one cycle per second.

FINDINGS

Participants with symptoms had a 38.5% greater thickness ratio and 39.2% greater shear strain index compared to participants without symptoms (p<0.05).

INTERPRETATION

Ultrasound detected differences the SSCT in symptomatic group that was characterized by low self-reported symptom severity scores. This study found ultrasound useful for measuring structural and functional changes in the SSCT that could provide insight in the early pathophysiology associated with carpal tunnel syndrome symptoms.

Validation of color Doppler sonography for evaluating relative displacement between the flexor tendon and subsynovial connective tissue

OBJECTIVES

A common pathologic finding in carpal tunnel syndrome is fibrosis and thickening of the subsynovial connective tissue. This finding suggests an etiology of excessive shear forces, with relative longitudinal displacement between the flexor tendon and adjacent subsynovial connective tissue. The purpose of this study was to validate color Doppler sonography for measurement of tendon displacement over time.

METHODS

Eight unmatched fresh frozen cadaver arms were used to evaluate color Doppler sonography for measurement of tendon displacement. The middle flexor digitorum superficialis tendon was moved through a physiologic excursion of 20 mm at 3 different tendon velocities (50, 100, and 150 mm/s).

RESULTS

We found that color Doppler sonography provided accurate measurement of tendon displacement, with absolute errors of -0.05 mm (50 mm/s), -1.24 mm (100 mm/s), and -2.36 mm (150 mm/s) on average throughout the tendon excursion range. Evaluating relative displacement between the tendon and subsynovial connective tissue during finger flexion-extension movements also offered insight into the gliding mechanism of the subsynovial connective tissue. During flexion, we observed a curvilinear increase in relative displacement, with greater differential motion at the end range of displacement, likely due to the sequential stretch of the fibrils between successive layers of the subsynovial connective tissue. In extension, there was a linear return in relative displacement, suggesting a different unloading mechanism characterized by uniform relaxation of fibrils.

CONCLUSIONS

We demonstrated the validity of color Doppler displacement for use in the evaluation of relative motion. Color Doppler sonography is useful in our understanding of the behavior of the subsynovial connective tissue during tendon excursion, which may elucidate the role of finger motion in the etiology of shear injury.

Assessment of image quality in soft tissue and bone visualization tasks for a dedicated extremity cone-beam CT system

OBJECTIVE

To assess visualization tasks using cone-beam CT (CBCT) compared to multi-detector CT (MDCT) for musculoskeletal extremity imaging.

METHODS

Ten cadaveric hands and ten knees were examined using a dedicated CBCT prototype and a clinical multi-detector CT using nominal protocols (80 kVp-108mAs for CBCT; 120 kVp- 300 mAs for MDCT). Soft tissue and bone visualization tasks were assessed by four radiologists using five-point satisfaction (for CBCT and MDCT individually) and five-point preference (side-by-side CBCT versus MDCT image quality comparison) rating tests. Ratings were analyzed using Kruskal-Wallis and Wilcoxon signed-rank tests, and observer agreement was assessed using the Kappa-statistic.

RESULTS

Knee CBCT images were rated "excellent" or "good" (median scores 5 and 4) for "bone" and "soft tissue" visualization tasks. Hand CBCT images were rated "excellent" or "adequate" (median scores 5 and 3) for "bone" and "soft tissue" visualization tasks. Preference tests rated CBCT equivalent or superior to MDCT for bone visualization and favoured the MDCT for soft tissue visualization tasks. Intraobserver agreement for CBCT satisfaction tests was fair to almost perfect (κ ~ 0.26-0.92), and interobserver agreement was fair to moderate (κ ~ 0.27-0.54).

CONCLUSION

CBCT provided excellent image quality for bone visualization and adequate image quality for soft tissue visualization tasks.

KEY POINTS

• CBCT provided adequate image quality for diagnostic tasks in extremity imaging. • CBCT images were "excellent" for "bone" and "good/adequate" for "soft tissue" visualization tasks. • CBCT image quality was equivalent/superior to MDCT for bone visualization tasks.

[THE COMBINATION OF RECURRENT INTUSSUSCEPTION DUODENAL, ZENKER DIVERTICULUM, HIATAL HERNIA AND HASTROPTOSIS AS A MANIFESTATION OF NON-DIFFERENT DYSPLASIA OF CONNECTIVE TISSUE]

Presented rare clinical case: a combination of recurrent intussusception duodenal, diverticulum Zenker, hiatal hernia and hastroptosis as a manifestation of non-different dysplasia of connective tissue. Special interest is recurrent intussusception upper horizontal portion duodenal in the bulb, is not detected when esophagogastroduodenoscopy.

Influence of MRI-based bone outline definition errors on external radiotherapy dose calculation accuracy in heterogeneous pseudo-CT images of prostate cancer patients

BACKGROUND

This work evaluates influences of susceptibility-induced bone outline shift and perturbations, and bone segmentation errors on external radiotherapy dose calculation accuracy in magnetic resonance imaging (MRI)-based pseudo-computed tomography (CT) images of the male pelvis.

MATERIAL AND METHODS

T₁/T₂*-weighted fast gradient echo, T₁-weighted spin echo and T₂-weighted fast spin echo images were used in bone detection investigation. Bone edge location and bone diameter in MRI were evaluated by comparing those in the images with actual physical measurements of fresh deer bones positioned in a gelatine phantom. Dose calculation accuracy in pseudo-CT images was investigated for 15 prostate cancer patients. Bone outlines in T₁/T₂*-weighted images were contoured and additional segmentation errors were simulated by expanding and contracting the bone contours with 1 mm spacing. Heterogeneous pseudo-CT images were constructed by adopting a technique transforming the MRI intensity values into Hounsfield units with separate conversion models within and outside of bone segment.

RESULTS

Bone edges and diameter in the phantom were illustrated correctly within a 1 mm-pixel size in MRI. Each 1 mm-sized systematic error in bone segment resulted in roughly 0.4% change to the prostate dose level in the pseudo-CT images. The prostate average (range) dose levels in pseudo-CT images with additional systematic bone segmentation errors of -2 mm, 0 mm and 2 mm were 0.5% (-0.5-1.4%), -0.2% (-1.0-0.7%), and -0.9% (-1.8-0.0%) compared to those in CT images, respectively, in volumetric modulated arc therapy treatment plans calculated by Monte Carlo algorithm.

CONCLUSIONS

Susceptibility-induced bone outline shift and perturbations do not result in substantial uncertainty for MRI-based dose calculation. Dose consistency of 2% can be achieved reliably for the prostate if heterogeneous pseudo-CT images are constructed with ≤± 2 mm systematic error in bone segment.

The impact of CBCT reconstruction and calibration for radiotherapy planning in the head and neck region - a phantom study

BACKGROUND

The applicability of cone-beam computed tomography (CBCT) image sets for dose calculation purposes relies on high image quality and CT number accuracy. In this study we have investigated the use of stoichiometric calibration for transforming CT numbers into physical parameters, in combination with a new CBCT scatter correction algorithm, focusing on head and neck geometries.

METHODS

CBCT projections were acquired using an On-Board-Imager (OBI v1.4; Varian Medical Systems) using both low- and high-dose clinical image acquisition protocols. The CBCT projections were reconstructed twice, using both the standard method (OBI) as well as an experimental pre-clinical reconstruction algorithm (Full Fan Experimental - FFE). Stoichiometric calibration was performed using both a phantom from CIRS with nine tissue equivalent inserts (ranging from lung to dense bone) as well as with a custom made cylindrical PMMA head and neck phantom with variable 'head' diameter and with cavities designed to fit the inserts from a Gammex RMI phantom. To benchmark the CBCT performance, the same calibration procedures were performed using two conventional CT scanners. For assessment of influence on dose-volume parameters, the head part of the anthropomorphic Alderson phantom was scanned, reconstructed with both CT and CBCT using the stoichiometric calibration curves, and finally used to compare IMRT dose calculations.

RESULTS

The stoichiometric CBCT calibrations with the CIRS phantom resulted in an excellent fit between calculated and measured CT numbers (R = 1.000 for all combinations tested), equivalent to the results for the conventional scanners. Using the PMMA phantom, the stoichiometric calibration curves again showed excellent agreement, although the OBI reconstruction showed marginally increasing deviation from the unity line as the phantom size decreased. For the dose-volume parameters, deviations well within 1% were seen between the different reconstruction methods and acquisition modes.

CONCLUSION

This study showed that the combination of an improved reconstruction method and stoichiometric calibration improved the CT number accuracy of CBCT scans acquired for head and neck phantoms. In particular, a radial size dependence of the scanned object similar to that in conventional CT could be achieved. Although high density inhomogeneities still are challenging for the reconstruction process, clinically acceptable agreement in key dose-volume parameters between CT-based and CBCT-based IMRT planning calculations on a humanoid phantom was found.

Reverberation clutter from subcutaneous tissue layers: simulation and in vivo demonstrations

The degradation of ultrasonic image quality is typically attributed to aberration and reverberation. Although the sources and impact of aberration are well understood, very little is known about the source and impact of image degradation caused by reverberation. Reverberation is typically associated with multiple reflections at two interfaces along the same propagation path, as with the arterial wall or a metal sphere. However, the reverberation that results in image degradation includes more complex interaction between the propagating wave and the tissue. Simulations of wave propagation in realistic and simplified models of the abdominal wall are used to illustrate the characteristics of coherent and diffuse clutter generated by reverberation. In the realistic models, diffuse reverberation clutter is divided into that originating from the tissue interfaces and that originating from sub-resolution diffuse scatterers. In the simplified models, the magnitude of the reverberation clutter is observed as angle and density of the connective tissue are altered. The results suggest that multi-path scattering from the connective tissue/fat interfaces is a dominant component of reverberation clutter. Diffuse reverberation clutter is maximal when the connective tissue is near normal to the beam direction and increases with the density of connective tissue layers at these large angles. The presence of a thick fascial or fibrous layer at the distal boundary of the abdominal wall magnifies the amount of reverberation clutter. The simulations also illustrate that compression of the abdominal layer, a technique often used to mitigate clutter in overweight and obese patients, increases the decay of reverberation clutter with depth. In addition, rotation of the transducer or steering of the beam with respect to highly reflecting boundaries can reduce coherent clutter and transform it to diffuse clutter, which can be further reduced using coherence-based beamforming techniques. In vivo images of the human bladder illustrate some of the reverberation effects observed in simulation.

Estimation of trochanteric soft tissue thickness from dual-energy X-ray absorptiometry

Low body mass index is considered to be an important risk factor for fractures in postmenopausal women, in part reflecting its association with lower bone mineral density (BMD). In contrast, obesity is thought to be protective against fracture because of higher BMD and reduced transmitted force of falls as a result of soft tissue padding. Dual-energy X-ray absorptiometry (DXA) is most widely used for the assessment of osteoporosis. We hypothesized that trochanteric soft tissue thickness, as measured directly on whole-body DXA scans, could be estimated using the regional measures of anteroposterior tissue thickness from hip and spine DXA. We identified 376 adult patients who underwent DXA evaluation of the lumbar spine, hip, and whole body at the same visit. The population was randomly divided into 2 equal-sized subgroups, one used to derive prediction equations for trochanteric soft tissue thickness and the other for independent validation. Compared with the actual measurement from the whole-body scans in the validation cohort, the DXA-based estimate gave an unbiased prediction of trochanteric soft tissue thickness (adjusted R² was 0.60 with a standard error of the estimate of 1.35cm), which was significantly better than estimation obtained without DXA information (p < 0.001). Area under the curve discrimination for trochanteric soft tissue thickness in the lowest and highest tertiles was 0.901 (95% confidence interval: 0.849-0.953) and 0.859 (95% confidence interval: 0.805-0.915), respectively. Model-based prediction of trochanteric soft tissue thickness in the lowest and highest tertiles had sensitivities of 78.5% and 91.9% and specificities of 64.4% and 86.8%, respectively. We conclude that regional DXA scans of the spine and hip can be used to estimate the trochanteric soft tissue thickness.

Ultrasound assessment of the entheses in primary Sjögren syndrome

Although tendon pain is commonly reported in primary Sjögren syndrome (pSS), the underlying mechanism is unknown. The objective of this study was to determine whether tendon pain in pSS is related to involvement of the tendons and entheses. We performed a physical examination of 288 entheseal insertion sites in 16 patients with active pSS and 162 entheseal insertion sites in 9 healthy controls without symptoms or medications. Then ultrasound was used to assess entheseal and tendon sites of these patients (n = 208) and controls (n = 117). Ultrasound was performed in B mode first to detect structural damages, and in power Doppler mode to detect blood flow abnormalities. By physical examination, 9 (56%) of the 16 pSS patients had pain to palpation of fibromyalgia tender points, two of whom had more than 11 tender points. The number of positive points ranged from 2 to 18, with a mean of 8 ± 6.0. None of the healthy controls had positive tender points. None had structural or blood-flow abnormalities by ultrasound. To conclude, this study provides the first data on ultrasound findings in patients with active pSS. Although 56% of patients had clinical tender points, none had structural or blood-flow abnormalities by ultrasound, suggesting the absence of inflammation of the tendons and entheses in this disease.

Accuracy improvement in Cranio-Maxillofacial soft tissue simulation using a muscle embedded meshing approach

In the presented paper, we propose to improve the state-of-the-art approach for Cranio-Maxillofacial (CMF) soft tissue simulation by considering a new image-based meshing approach that accurately models the interface between different tissue types. The proposed approach has been initially evaluated on soft tissue deformations of four patients undergoing CMF surgery using post-operative CT scans. The results indicate improved prediction and robustness of the surgical planning outcome when compared to the state-of-the-art method while decreasing the simulation time.

Systemic connective tissue abnormalities in patients with saccular intracranial aneurysms

OBJECTIVES

Our purpose was to identify the incidence and significance of markers of systemic connective tissue abnormalities (CTA) in patients with saccular intracranial aneurysms (SIA).

MATERIALS AND METHODS

This prospective case-control study included 199 consecutive patients with SIA (103 women and 96 men, mean age - 43.2 years) and 194 control patients - blood donors (108 - men, 86 - women, mean age - 38.4 years). Aneurysms were verified by conventional cerebral angiography. All patients were examined by the first author using a specially designed questionnaire and a standardized physical examination with special emphasis on systemic CTA.

RESULTS

Twelve markers of systemic CTA were significantly higher in patients with SIA than in controls: visible vessels on face and chest (59.8%), scoliosis (44.7%), varicose veins in legs (39.7%), flatfoot (34.6%), hyperextensibility of the skin (33.6%), spontaneous epistaxis (25.6%), easy bruising (20.6%), abdominal hernia (13.6%), periodontal disease (10.5%), chest deformations (7.5%), abdominal striae (3.5%), joint hypermobility (2.5%). A blinded validation study in a subset of 43 patients showed similar results. Among patients with SIA, 125 of 199 patients (62.8%) had at least three markers of systemic CTA compared with 23 (11.8%) of the controls (P < 0.0001, OR = 12.5, 95% CI 7.45-21.1). The mean number of markers of systemic CTA in patients with SIA was 3.07 and 1.17 in controls.

CONCLUSION

Patients with SIA have multiple markers of systemic connective tissue abnormalities. Systemic weakness of connective tissue represents a risk factor for development of SIA. Identification of these markers may help in detection of high-risk patients.

Desmoplastic ameloblastoma: a rare odontogenic neoplasm with unusual radiographic and histomorphological presentation

Desmoplastic ameloblastoma (DA) is a newly recognised, rare odontogenic neoplasm that is a histological variant of ameloblastoma. In this type, the islands of ameloblastoma are surrounded and often compressed by a dense and sometimes hyalinised fibrous connective tissue. Although ameloblastomas are usually located in the mandible, this variant often occurs in the anterior maxilla. In view of the paucity of DA case series and only limited understanding of its biological behaviour and prognosis, proper treatment strategies for DA are not entirely defined so far. The purpose of this paper was to review the literature and to demonstrate a rare case for an improved understanding of the behaviour and prognosis of DA.

Mammographic density: intersection of science, the law, and clinical practice

High mammographic density is associated with a two- to sixfold increased risk of breast cancer. Mammographic density can be altered by endogenous and exogenous hormonal factors and generally declines with age. Mammographic density is affected by confounding factors such as age, parity, menopausal status, and body mass index (BMI), thus making interpretation of mammographic density challenging. None of the established means of measuring mammographic density are entirely satisfactory because they are time consuming and/or subjective. Although mammographic density has been shown to predict breast cancer risk, the role of mammographic density in precisely assessing a woman's breast cancer risk over her lifetime and evaluating response to risk-reduction strategies cannot be fully realized until we have a better understanding of the biology that links mammographic density to breast cancer risk.

Mammographic density and risk of breast cancer

The radiographic appearance of the breast on mammography varies among women, and reflects variations in breast tissue composition and the different X-ray attenuation characteristics of these tissues. Fat is radiologically lucent and appears dark on a mammogram. Connective and epithelial tissues are radiologically dense and appear light. These variations in appearance are commonly described as the percentage of the breast image that is radiologically dense, or as percent mammographic density (PMD). There is now extensive evidence that PMD is a risk factor for breast cancer, with a 4- to 6-fold gradient in risk between women with 75% or more PMD compared with those with 10% or less. However, the accuracy of risk prediction in individual women is modest. The extent of PMD is associated inversely with greater age, parity, and weight, and is reduced by the menopause and by tamoxifen. PMD is positively associated with greater height, a family history of breast cancer, and is increased by combined hormone therapy. The relative risk associated with density is substantially larger than the relative risk of breast cancer associated with a family history of the disease or any of the menstrual and reproductive risk factors. It is estimated that the risks of breast cancer attributable to density of 50% or more may be 16% for all breast cancers. Although combined hormone therapy and tamoxifen respectively increase a decrease both PMD and breast cancer risk, there is as yet insufficient evidence to use PMD as a surrogate marker for breast cancer.

Anterior pelvic soft tissue thickness influences acetabular cup positioning with imageless navigation

The purpose of this study was to investigate acetabular component position after total hip arthroplasty correlating both version and inclination to anterior pelvic soft tissue thickness. Thirty patients with a mean age of 66.5 ± 14 (28-87) years and an average body mass index of 30.04 ± 4.6 were included. The same surgeon operated on all 30 patients, using an anterolateral approach in a supine position and an imageless navigation system. Postoperative assessment of cup inclination, cup anteversion, and soft tissue thickness was measured by an independent research associate using computed tomographic scans. Pearson's moment correlations did not reveal any significant relationships between body mass index, soft tissue thickness, final intraoperative, or postoperative cup position. Anterior soft tissue thickness had no significant effect on the accuracy of acetabular cup positioning.

Sonographic measurements of subsynovial connective tissue thickness in patients with carpal tunnel syndrome

OBJECTIVES

A major pathologic finding in patients with idiopathic carpal tunnel syndrome is noninflammatory fibrosis and thickening of the subsynovial connective tissue. The objective of this study was to determine the ability of sonography to depict this thickening by comparing subsynovial connective tissue thickness in patients with carpal tunnel syndrome and healthy control participants.

METHODS

Longitudinal sonograms of the middle finger superficial flexor tendon and subsynovial connective tissue were obtained at 3 levels: at the wrist crease (proximal tunnel), at the hook of the hamate (mid tunnel), and at the distal edge of the transverse carpal ligament (distal tunnel). The thickness of the subsynovial connective tissue perpendicular to the direction of the tendon and the diameter of the flexor digitorum superficialis tendon at the same level were measured. Then, a thickness ratio was created.

RESULTS

At all 3 levels, the subsynovial connective tissue was thicker in patients than in controls (P < .0001) with a thickness ranging from 0.60 to 0.63 mm in patients and 0.46 to 0.50 mm in controls. The thickness ratio was significantly greater in patients at the hamate and distal levels (P = .018 and .013, respectively).

CONCLUSIONS

With this study, we have shown that it is possible to measure subsynovial connective tissue thickness with sonography, and the tissue is thicker in patients with carpal tunnel syndrome than in healthy controls.

[Feature analysis of superficial soft tissue interface based on wave numbers]

Based on a simple deconvolution model of multi-layer interfaces, the reasons of wave number variation of the interfacial echo signal were analyzed to explore a method for feature recognition of the superficial soft tissue interfaces. The interfacial echo signal data were decomposed and reconstructed by Mallat multisolution analysis, with the number of the reconstructed interface signal as the feature. The results showed that the deconvolution model was effective for extracting the interface echo signal features in the superficial soft tissue and allowed identification and location of tissue defects.