Anatomical Features Research Articles

Computer-assisted total bilateral knee arthroplasty for a patient with severe hyperextension in residual poliomyelitis: a case report

Background. Total knee arthroplasty in patients in the residual stage of poliomyelitis is a technically difficult job. The reasons for this are anatomical features and therefore difficulties in an implant choice and conflicting results. In the present case report, we describe a unique method of a computer-navigated installation of a rotating-hinge implant in a non-standard position for a patient with residual poliomyelitis. The aim of the study is to demonstrate a method of a computer-navigated installation of rotating-hinge knee implants in a patient with severe hyperextension and valgus deformity in the residual stage of poliomyelitis. Case description. The clinical case presents a 55-year-old man with lower peripheral paraparesis as a consequence of poliomyelitis and bilateral valgus knee arthritis with severe hyperextension. The patient moved on crutches at a distance no more than 300 meters. Two-stage total knee arthroplasty was performed using a navigation system and second-generation rotating-hinge implants. At the 4-year follow-up period, we note a good clinical result, and the patient is satisfied with the total knee arthroplasty outcomes. Conclusion. The clinical case demonstrates good results of performing total knee arthroplasty in a patient with bilateral severe hyperextension and knee valgus deformity in residual poliomyelitis. Having analyzed available topic-related literature, we developed an original method of a computer-navigated installation of a second-generation rotating-hinge implant. The method can be an effective treatment solution for patients with knee arthritis deformity in the residual stage of poliomyelitis.

Histological Definition of Skeletal Muscle Injury: A Guide to Nomenclature Along the Connective Tissue Sheath/Structure.

Recent years have seen the development of various classifications of muscle injuries, primarily based on the topographic location within the bone-tendon-muscle chain. This paper proposes an enhanced nomenclature for muscle injuries that incorporates histoarchitectural definitions alongside topographic classifications, emphasizing the importance of connective tissue damage characterization. A detailed understanding of the distinct anatomical and histological characteristics of tendon, aponeurosis, and fascia is essential for consistent terminology. Tendons, aponeuroses, and fasciae, while all composed of dense connective tissue, differ in collagen fiber orientation and structural organization. Tendons feature longitudinally aligned fibers suited for high tensile forces and muscle-to-bone connections. Aponeuroses have perpendicular collagen fiber layers, allowing for force distribution and support for both longitudinal and transverse traction. Fasciae exhibit loosely organized fibers providing flexibility and movement between muscles. The continuity and differences within the musculotendinous frameworks, particularly at the musculotendinous junction (MTJ), elucidate the higher frequency of injuries at these sites compared with tendons, highlighting the MTJ's role as a stress-absorbing 'safety valve.'

Selective Adipose Cryolysis for Reduction of Lingual Tissue in a Porcine Model.

Oropharyngeal fat volume is associated with obstructive sleep apnea (OSA) severity. Selective adipose cryolysis may produce cold-induced adipose cell death while sparing surrounding tissues. This study explored (1) similarities in tongue fat between porcine and human models and (2) the feasibility and potential reduction of lingual fat using selective adipose cryolysis. Porcine model. Preclinical research laboratory under IACUC-approved protocols. Anatomical, histological, and biochemical characterizations of tongue tissue from 6 porcine and 4 human cadaver specimens were conducted to establish comparative frameworks. Comparison of fat distribution and composition was conducted via image analysis of histological sections as well as gas chromatography analysis of fatty acid composition. Safety and efficacy of selective adipose cryolysis were evaluated in an additional 16 porcine animals using a prototype cooling system. Histological analysis examined tissue response at 3, 6, 30, and 45 d posttreatment. Comparative analysis revealed similar fat distribution and composition between human and porcine tongues. Selective adipose cryolysis induced progressive reduction in treated area tongue fat content at all timepoints, from 42% at baseline to 32% (t = 3 d) and 14% (t = 30 d), accompanied by macrophage infiltration, crown-like structure formation, and tissue remodeling. Selective adipose cryolysis holds promise as a targeted therapeutic approach for reducing lingual fat in humans. The porcine model may provide valuable insight into treatment mechanisms and support initial translational work. Further research is warranted to elucidate long-term treatment outcomes and optimize clinical implementation strategies, with the goal of improving management of OSA in humans.

A database and interactive identification key for the anatomy of woods of the Ethiopian Afromontane Forest

Summary Identifying wood and wood charcoal from sub-tropical to tropical regions is challenging, due to the high floristic diversity. This is especially true for the Horn of Africa, characterized by a high degree of endemism, for which no wood anatomy atlas is available. Yet, there is a strong need for anatomical descriptions and identification tools, in particular concerning archaeobotanical research. Numerous rock shelters in the Ethiopian highlands provide rich charcoal assemblages. Their study is of utmost interest to decipher past human-vegetation relationships. Many of these sites are located in the Afromontane Forest, the potential natural vegetation of the highlands within the Eastern Afromontane biodiversity hotspot, hosting 483 dicot woody species. Here, we present the first wood database for the species of the Ethiopian Afromontane Forest. It is set up on the online open-access platform Xper3 and includes an interactive identification key. The anatomical features follow the IAWA nomenclature and include additional ones, to improve the identification process. The database comprises wood anatomical descriptions of (1) 68 species from the wood reference collections of Addis Ababa University, Ethiopia, and Goethe University, Frankfurt, Germany; (2) 72 species from InsideWood and (3) 92 genera/species from specialized literature. The database also includes original pictures taken on samples from the reference collections. Our original coded descriptions and pictures are also available in InsideWood.

Unveiling the embryo structure in Bromeliaceae Juss. (Poales): morphological diversity, anatomy, and character evolution.

Recent studies have documented numerous morphoanatomical variations for the seed coat in Bromeliaceae. However, the structural diversity and character evolution of the embryo within this family remain largely unexplored. Given the embryo's significance in plant diversification, this research aims to investigate the morphology and key anatomical features of Bromeliaceae embryos, providing insights into character evolution, taxonomic applications, and reproductive biology. We analysed samples of 88 species from 50 genera representing the major lineages of Bromeliaceae, using standard plant microtechniques adapted for seeds. To determine ancestral traits, parsimony and maximum likelihood analyses were performed in a consensus supertree combining previous phylogenies. This study identified 14 informative characters, highlighting significant differences among groups, particularly in embryo morphology, differentiation, and anatomical traits. Our analysis revealed that undifferentiated embryos with a vestigial cotyledonary hyperphyll are plesiomorphic in Bromeliaceae. They have evolved multiple times into rudimentary or well-differentiated embryos, the latter exhibiting intermediate or large sizes and diverse cotyledonary hyperphyll morphologies. The cotyledonary hypophyll varies in sheath lobes and slit morphologies, and is curved or expanded exclusively in Bromelioideae representatives. Similarly, several patterns of hypocotyl/radicle constriction are unique to Tillandsioideae and plesiomorphic for this clade. Although rudimentary embryos exhibit simpler and more uniform anatomy, they are distinct from undifferentiated embryos, which lack defined organs and internal tissues. In contrast, well-differentiated embryos possess more complex anatomical structures, including a multi-layered shoot apical meristem and root cap, a broad cotyledonary sheath, and often leaf primordia, the latter evolving independently several times only in large embryos. Our findings reveal a previously unknown morphological diversity for embryos in Bromeliaceae, enhancing our understanding of the morphological evolution of its major lineages. In addition, it introduces new informative characters for the family's systematics and broadens our understanding of the reproductive biology of Bromeliaceae.

Novel neural network classification of maternal fetal ultrasound planes through optimized feature selection

Ultrasound (US) imaging is an essential diagnostic technique in prenatal care, enabling enhanced surveillance of fetal growth and development. Fetal ultrasonography standard planes are crucial for evaluating fetal development parameters and detecting abnormalities. Real-time imaging, low cost, non-invasiveness, and accessibility make US imaging indispensable in clinical practice. However, acquiring fetal US planes with correct fetal anatomical features is a difficult and time-consuming task, even for experienced sonographers. Medical imaging using AI shows promise for addressing current challenges. In response to this challenge, a Deep Learning (DL)-based automated categorization method for maternal fetal US planes are introduced to enhance detection efficiency and diagnosis accuracy. This paper presents a hybrid optimization technique for feature selection and introduces a novel Radial Basis Function Neural Network (RBFNN) for reliable maternal fetal US plane classification. A large dataset of maternal–fetal screening US images was collected from publicly available sources and categorized into six groups: the four fetal anatomical planes, the mother's cervix, and an additional category. Feature extraction is performed using Gray-Level Co-occurrence Matrix (GLCM), and optimization methods such as Particle Swarm Optimization (PSO), Grey Wolf Optimization (GWO), and a hybrid Particle Swarm Optimization and Grey Wolf Optimization (PSOGWO) approach are utilized to select the most relevant features. The optimized features from each algorithm are then input into both conventional and proposed DL models. Experimental results indicate that the proposed approach surpasses conventional DL models in performance. Furthermore, the proposed model is evaluated against previously published models, showcasing its superior classification accuracy. In conclusion, our proposed approach provides a solid foundation for automating the classification of fetal US planes, leveraging optimization and DL techniques to enhance prenatal diagnosis and care.

Anatomy and histology of the olfactory organ of the javelin goby Synechogobius hasta (Gobiiformes, Gobiidae)

The olfactory organ of Synechogobius hasta was investigated with a focus on its environmental adaptation, using stereo microscopy and light microscopy. This research revealed the following anatomical and histological characteristics: (i) tubular anterior nostril, (ii) one longitudinal lamella, (iii) two accessory nasal sacs, (iv) lymphatic cells in the lower part of the sensory epithelium, (v) four to five villi of olfactory receptor neurons, (vi) abundant blood capillaries beneath the sensory epithelium, and (vii) rod-shaped erythrocytes. These findings hint that the olfactory organ of S. hasta has anatomical and histological adaptations to intertidal pools that undergo periodic hypoxia and increased temperature under stagnant water conditions due to the tidal cycle.

Re-evaluation of Pterodactylus antiquus and Diopecephalus kochi: two troublesome taxonomic concepts

The taxonomic histories of Pterodactylus antiquus and other pterodactyloids from the Upper Jurassic plattenkalks of southern Germany are long and complex, reflecting centuries of intricate and often contentious research. Among the most debated issues in pterosaur taxonomy is the relationship between Pterodactylus antiquus and Diopecephalus (Pterodactylus) kochi. Three distinct interpretations of their relationship have been proposed: (1) P. antiquus and D. kochi are conspecific and part of an ontogenetic sequence; (2) P. antiquus and D. kochi are sister taxa; (3) P. antiquus and D. kochi are distinct taxa and are not each other's closest relatives. Through an analysis of key anatomical features, including skull morphology, dentition and autopodial anatomy, we demonstrate that P. antiquus and D. kochi are distinct taxa that do not share close affinities. Phylogenetic analysis recovered D. kochi as the most basal member of Pterodactyloidea, retaining autopodial features comparable with those of non-pterodactyloids. Set within a temporal framework, this analysis challenges traditional assumptions regarding the pattern and timing of pterodactyloid evolution in the Jurassic, hinting at a longer and more complex history than previously realized.

Identification of Vertebrae in CT Scans for Improved Clinical Outcomes Using Advanced Image Segmentation

This study proposes a comprehensive framework for the segmentation and identification of vertebrae in CT scans using a combination of deep learning and traditional machine learning techniques. The Res U-Net architecture is employed to achieve a high model accuracy of 93.62% on the VerSe’20 dataset demonstrating effective performance in segmenting lumbar and thoracic vertebrae. Feature extraction is enhanced through the application of Otsu’s method which effectively distinguishes the vertebrae from the surrounding tissue. The proposed method achieves a Dice Similarity Coefficient (DSC) of 87.10% ± 3.72%, showcasing its competitive performance against other segmentation techniques. By accurately extracting vertebral features this framework assists medical professionals in precise preoperative planning, allowing for the identification and marking of critical anatomical features required during spinal fusion procedures. This integrated approach not only addresses the challenges of vertebrae segmentation but also offers a scalable and efficient solution for analyzing large-scale medical imaging datasets with the potential to significantly improve clinical workflows and patient outcomes.

Body size and evolutionary rate analyses reveal complex evolutionary history of Alvarezsauria.

Some of the smallest examples of dinosaurian body size are from alvarezsaurians, an enigmatic group of maniraptoran coelurosaurians with a peculiar combination of anatomical features unique among theropods. Despite the large number of alvarezsaurian species described worldwide and the increased understanding this has provided, the body-size macroevolution of alvarezsaurians has received little attention. Here we reconstruct and analyse directional trends of alvarezsaurian body-size evolution through an integrated analysis of body mass, ontogenetic age, and morphological rate data enabled by a comprehensively revised phylogeny. Our analyses identify four periods of high morphological rate evolution (Bathonian-Callovian, Hauterivian-early Berriasian, early Cenomanian, and late Cenomanian-Turonian) that we link to the key effects of animal body-size changes for the first time, including morphological novelty, structural reduction and simplification, elevated homoplasy, and behavioral changes associated with miniaturization. In doing so, this study provides a holistic example of miniaturization in a Mesozoic vertebrate group that offers a framework for other detailed studies of animal body-size evolution, including in more disparate groups.

Vertex Augmentation With Hyaluronic Acid Filler: A Novel Technique for Height Enhancement and Cephalic Contouring.

Height augmentation and cephalic contouring using hyaluronic acid (HA) fillers represent an innovative approach in minimally invasive aesthetic medicine. This study introduces a novel technique for vertex augmentation, leveraging cross-linked HA fillers to achieve subtle height enhancement and cephalic contouring. A 42-year-old male patient seeking non-surgical height augmentation underwent vertex injections with 15ml of HA filler (e.p.t.q. eve X, Jetema Inc., Seoul, Republic of Korea), using a multidirectional spreading technique under local anesthesia. The procedure resulted in an immediate and sustained 1.2cm height increase with no adverse effects at a 6-month follow-up. The vertex's low vascularity and favorable anatomic features minimized complications and enhanced safety. This method also holds potential for cephalic contouring in female patients, providing subtle cranial volume for aesthetic purposes. The findings highlight the adaptability of HA fillers beyond traditional facial applications, offering a safe, effective alternative to surgical interventions. Further studies are encouraged to validate long-term outcomes and expand patient applicability.

Stent retriever expansion as a corrective maneuver to optimize inadequately deployed flow diverter stents.

As flow diversion (FD) is becoming increasingly important in the endovascular treatment of intracranial aneurysms, the rate of technical complications is also increasing. Inadequate FD implantation may lead to both ischemic complications and decreased treatment efficacy. The aim of this study was to evaluate the efficacy of off-label stent retriever (SR) use in managing technical complications associated with FD implantation. A retrospective analysis of data from patients who underwent FD treatment at two neuroradiology centers was performed. The objective was to identify cases in which the FD was inadequately deployed and SR expansion was performed as a corrective maneuver. The analysis included anatomic characteristics, technical information, angiographic and clinical outcomes, and complications. A total of 35 corrective maneuvers with SR were performed in 25 FD treatments. The corrective maneuvers in all treatments were successful, and no additional devices or therapies were required. No procedural complications or technical difficulties were documented. With the growing role of FDs in neurointerventional treatment, familiarity with corrective maneuvers after technical complications or inadequate implantation is important. The findings in our selected cohort demonstrated that SR expansion is an effective and safe corrective maneuver for incompletely opened FDs.

Gross anatomical features of the insular cortex in affective disorders

IntroductionThe number of insular gyri is elevated in patients with schizophrenia. Thus, it has potential as a marker of early neurodevelopmental abnormalities. However, currently it remains unclear whether patients with other neuropsychiatric disorders, such as affective disorders, also have this gross brain anatomical feature.Materials and methodsThe macroscopic features of the insular cortex in 26 patients with bipolar disorder (BD), 56 with major depressive disorder (MDD), and control subjects for each clinical group (24 for BD and 33 for MDD) were assessed using magnetic resonance imaging.ResultsThe number of short insular gyri was higher in BD patients than in matched controls bilaterally with well-developed accessory and middle short gyri. Furthermore, the left middle short gyrus was more developed in MDD patients than in matched controls, and was weakly associated with the severity of depressive symptoms.DiscussionThe present results indicate that changes in the gross morphology of the insular cortex in BD and MDD is a potential vulnerability factor associated with their neurodevelopmental pathologies, and may also contribute to the severity of symptoms in MDD.

Local Anesthesia With 1% Lidocaine Versus General Anesthesia for Percutaneous Endoscopic Interlaminar Discectomy at L5/S1 Disc Herniation​​​: A Prospective Randomized Study.

A prospective randomized clinical trial. In this study, we compared local anesthesia with 1% lidocaine (LA) and general anesthesia (GA) utilized in PEID at L5/S1 disc herniation. Given the anatomic characteristics of L5/S1 segment, interlaminar approach was preferred to perform endoscopic discectomy for L5/S1 disc herniation. Typically, general anesthesia was used for interlaminar approach. However, with general anesthesia, nerve damage during surgery due to being unable to monitor patient status is a main concerned for surgeons. As an alternative option, local anesthesia has been developed recently. But, the optimal type of anesthesia for PEID remains controversial. From March 2021 to March 2023, 103 consecutive patients with L5/S1 disc herniation who planned to undergo PEID in our unit were randomized to the LA group (n=53) or GA group (n=50). Both groups were followed up for at least 24 months. Surgical-related parameters, clinical outcomes, and complications were compared between the 2 groups. The mean operative time and bed rest time were shorter in the LA group than in the GA group (both P<0.001). The estimated blood loss in the LA group was greater than that in the GA group (P<0.001). The cost of hospitalization in the LA group was significantly lower than that in the GA group (P<0.001). At every time point of follow-up, there was no significant difference between the 2 groups in terms of VAS, ODI, and modified MacNab criteria. The satisfaction surveys showed that more patients in the LA group would choose contrary anesthesia, including 6 patients who were administered extravenously injected sufentanil intraoperatively due to intensive pain. Postoperative neuropathic abnormalities were rarer in the LA group. Both local anesthesia using 1% lidocaine and general anesthesia are effective and safe for PEID at the L5/S1 segment. The use of local anesthesia is preferable due to its associated reductions in operative time, bed rest duration, and economic costs.

Anatomical and histological analyses of ankle plantar flexors: insights into connective tissue composition and muscle architecture.

The tibialis posterior (TP), flexor digitorum longus (FDL), and flexor hallucis longus (FHL) are muscles that contribute to the stability of foot and ankle movements, playing a crucial role in achieving optimal gait. However, a comprehensive examination of the anatomical characteristics and histological variances of each muscle has not been conclusively established. A total of 10 un-embalmed cadavers were dissected, and muscles from each cadaver were consistently harvested from the musculotendon junction. The ratio of collagen and elastic fibers was assessed through three immunohistological analyses, focusing on distinct histological characteristics in type I (slow twitch) and type II (fast twitch) fibers. Additionally, Ultrasonography was utilized to compare and analyze the thickness, fascicle angle, and muscle fiber length of each muscle. Concerning the relative proportion of elastic fibers to collagen, the TP exhibited the highest collagen content (21.9 ± 0.30%, mean ± standard deviation), while the FHL had the highest elastic fiber proportion (48.4 ± 0.44%). The TP predominantly comprised slow type muscle fibers (36.88 ± 0.83%), whereas the FHL contained a higher density of fast type muscle fibers (32.46 ± 4.02%). US analysis indicated that the thickness of the TP was relatively greater (2.0 ± 0.2mm) compared to the FDL (1.2 ± 0.1mm) and FHL (1.1 ± 0.1mm). Additionally, the fascicle length was notably longer in the TP (25.6 ± 4.1mm). Our anatomical and histological findings indicate that the tibialis posterior (TP) is the thickest with a significant physiological angle and a high collagen content. This characteristic enables the TP to provide stability by transmitting a constant force to the calf. On the other hand, the flexor hallucis longus (FHL) exhibits the highest elastic fiber content, confirming its ability to exert instantaneous, swift, and powerful force.

Probing the limits and capabilities of diffusion models for the anatomic editing of digital twins

Numerical simulations of cardiovascular device deployment within digital twins of patient-specific anatomy can expedite and de-risk the device design process. Nonetheless, the exclusive use of patient-specific data constrains the anatomic variability that can be explored. We study how Latent Diffusion Models (LDMs) can edit digital twins to create digital siblings. Siblings can serve as the basis for comparative simulations, which can reveal how subtle anatomic variations impact device deployment, and augment virtual cohorts for improved device assessment. Using a case example centered on cardiac anatomy, we study various methods to generate digital siblings. We specifically introduce anatomic variation at different spatial scales or within localized regions, demonstrating the existence of bias toward common anatomic features. We furthermore leverage this bias for virtual cohort augmentation through selective editing, addressing issues related to dataset imbalance and diversity. Our framework delineates the capabilities of diffusion models in synthesizing anatomic variation for numerical simulation studies.

Morphofunctional features of the fallopian tubes. Modern concepts

The article provides an overview of the modern literature covering the role of the fallopian tubes in reproduction. The understanding of the anatomy and functions of the fallopian tubes has changed several times over the centuries. There is still no generally accepted opinion regarding some of the features of their structure. The normal functioning of the fallopian tubes is possible only due to the complex interaction of physical and biochemical processes occurring therein. In recent years, many discoveries have been made regarding the fallopian tubes that showed that we still do not know all the details of how this organ works. There are several basic methods for assessing the functions of the fallopian tubes, but all of them have their drawbacks and are of limited use, which is why it can sometimes be quite difficult to get a complete picture of the organ’s functioning. Modern discoveries and the introduction of new techniques into practical work can significantly expand the doctor’s capabilities in treating infertility associated with the tubal factor. The current knowledge about the anatomical, functional and morphological features of the fallopian tubes emphasizes the importance of this organ in the implementation of the woman’s reproductive function. It is generally believed that the role of the fallopian tubes in conception is secondary and unimportant in comparison with the tasks performed by the uterus and ovaries. The importance of the fallopian tubes is most often mentioned in the literature in no more than a few paragraphs, where it is said only that the egg moves through them to the uterine cavity. However, modern research proves that complex processes and interactions occur in the organ that maintain homeostasis therein. After all, only the totality of the preserved function of each of the organs of the female reproductive system can ensure the onset and prolongation of future pregnancy.

Characteristics of the femoral tunnel of anatomical and isometric single bundle anterior cruciate ligament reconstruction: a modeling analysis based on quadrant method and anatomical landmarks

PurposeTo investigate the anatomical features of the femoral tunnel in anatomical and isometric single-bundle ACL reconstruction.MethodThirty-two 3-dimensional knee models were reconstructed based on CT scan (average age: 26.5 ± 6.7 years, 18 males and 14 females, 17 left and 15 right). Multiple anatomical landmarks were identified. Virtual femoral tunnels were created at the deep and high portion of ACL footprint, close to the lateral intercondylar ridge to achieve best anatomy and isometry, simulating an anteromedial portal reconstruction. Anatomical features of the femoral tunnels were analyzed. The position of the femoral tunnel was quantified by the distance to anatomical landmarks and using quadrant methods. The spatial angles, length and outer opening of the femoral tunnels were also evaluated.ResultsAcceptable tunnels were created in all models. The center of femoral tunnel was slightly higher than the apex of deep cartilage, near the deep one-third point across the shallow-deep dimension of the lateral femoral condyle. Using the quadrant method, the tunnel was located at 28.4% ± 2.2% and 22.2% ± 3.6%, parallel and perpendicular to the Blumensaat line, respectively. The spatial angles of the tunnel were 40°, 33.5° ± 4.1° and 38.2° ± 4.4° on the sagittal, transverse, and coronal planes, respectively. The average tunnel length was 34.8 mm ± 3.8 mm. The outer opening of the tunnels was located at the posterior one-third of the femoral metaphysis.ConclusionThe anatomical and isometric positioning of the femoral tunnel can be achieved through anteromedial portal with satisfied tunnel characteristics. The apex of deep cartilage may be used as an anatomical reference for tunnel positioning. When drilled at appropriate orientation, favorable tunnel length, integrity and position of the outer opening can be obtained.

The use of a vascularized fibular flap in the treatment and surgical rehabilitation of military trauma patients

Aim. The purpose of the work is to demonstrate the possibilities of using a vascularized fibular flap to replace bone defects in the treatment of acute military trauma and its consequences at the rehabilitation stage. Materials and methods. An anatomical feature description of the vascularized fibular flap with a cutaneous component. Clinical cases of the vascularized fibular flap use to reconstruct bone and soft tissue defects after military injuries. In the presented cases, vascularized fibula osteocutaneous flaps were used. Results. Two clinical cases of reconstruction using the fibula flap are presented. The first case presents a patient with a total mandibular defect resulting from a gunshot wound. The second case presents a patient with consequences of a mine-shrapnel injury of the left forearm and an ulnar defect of about 12 cm in length and the resultant inability to perform rotational movements. Vascularized fibula osteocutaneous flaps were used for reconstruction in both cases being transferred to the recipient site, and microvascular anastomoses were performed for flap reperfusion. Conclusions. Adding a free fibula flap to the reconstructive surgeon’s arsenal enables one-stage reconstructions of large wounds with bone defects after injuries or oncological resections without significant musculoskeletal functional loss to donor limbs.

The temporal specificity of BOLD fMRI is systematically related to anatomical and vascular features of the human brain

Abstract The ability to detect fast responses with functional MRI depends on the speed of hemodynamic responses to neural activity, because hemodynamic responses act as a temporal low-pass filter which blurs rapid changes. However, the shape and timing of hemodynamic responses are highly variable across the brain and across stimuli. This heterogeneity of responses implies that the temporal specificity of fMRI signals, or the ability of fMRI to preserve fast information, could also vary substantially across the cortex. In this work we investigated how local differences in hemodynamic response timing affect the temporal specificity of fMRI. We used ultra-high field (7T) fMRI at high spatiotemporal resolution, studying the primary visual cortex (V1) as a model area for investigation. We used visual stimuli oscillating at slow and fast frequencies to probe the temporal specificity of individual voxels. As expected, we identified substantial variability in temporal specificity, with some voxels preserving their responses to fast neural activity more effectively than others. We investigated which voxels had the highest temporal specificity, and tested whether voxel timing was related to anatomical and vascular features. We found that low temporal specificity is only weakly explained by the presence of large veins or cerebral cortical depth. Notably, however, temporal specificity depended strongly on a voxel’s position along the anterior-posterior anatomical axis of V1, with voxels within the calcarine sulcus being capable of preserving close to 25% of their amplitude as the frequency of stimulation increased from 0.05Hz to 0.20Hz, and voxels nearest to the occipital pole preserving less than 18%. These results indicate that detection biases in high-resolution fMRI will depend on the anatomical and vascular features of the area being imaged, and that these biases will differ depending on the timing of the underlying neuronal activity. While we attribute this variance primarily to hemodynamic effects, neuronal nonlinearities may also influence response timing. Importantly, this spatial heterogeneity of temporal specificity suggests that it could be exploited to achieve higher specificity in some locations, and that tailored data analysis strategies may help improve the detection and interpretation of fast fMRI responses.