Tomography Scan Research Articles

Cranial Shape Changes in Nonsyndromic Unilateral Lambdoid Synostosis after Open Posterior Vault Remodeling.

The purpose of this study was to quantify change in cranial morphology in patients with nonsyndromic unilateral lambdoid craniosynostosis (ULC) from presentation (t0), after open posterior switch-cranioplasty (t1), and at 2-year follow-up (t2). Volumetric, linear, and angular analysis were performed on computed tomographic scans at the three time points and against normal control subjects. Significance was set at P < 0.05. Twenty-two patients were included. ULC cranial vault asymmetry index was higher than in control subjects before surgery (6.22 ± 3.55) but decreased after surgery (3.00 ± 2.53) to become comparable with the normal asymmetry range present in the controls. After surgery, both diagonals increased, but more on the fused side. In the 2 years after surgery, both diagonals in patients with ULC grew proportionately, but the fused diagonal remained slightly shorter than the patent side. Total cranial volume was higher in patients with ULC than in control subjects after surgery but became comparable at t2. Cranial base angulation improved by t2 but did not approach normal, and ear position remained unchanged. The facial twist was higher than in controls at t0 and t1 but was comparable at t2. Coronal asymmetry improved with surgery but remained undercorrected at t2, with the greatest residual asymmetry at opisthion. Open-switch cranioplasty normalizes cranial vault asymmetry index by increasing the fused cranial diagonal more than the patent side and is stable at 2 years. Skull base twist does not normalize, but facial twist approaches normal. Technique improvement should focus on residual coronal asymmetry present at opisthion. Therapeutic, IV.

An Unusual Case of Pyogenic Liver Abscess Secondary to Achromobacter xylosoxidans

Abstract Achromobacter xylosoxidans is a catalase-positive, oxidase-positive, motile, gram-negative rod. When isolated, it is usually a cause of bacteremia in immunocompromised patients. Here we present a case of liver abscess caused by this rare organism in an immunocompetent host. A 57-year-old Colombian woman came to the emergency department with complaints of subacute onset of back pain, burning in urination, fever, nausea, and vomiting. She was febrile and tachycardic. Urinalysis was positive for leukocyte esterase, nitrite, and bacteria. The patient was started on empiric piperacillin tazobactam 3375 mg as intravenous piggyback every 8 hours. On day 3 of hospitalization, the patient continued to experience flank pain without improvement. Computed tomographic scan of the abdomen and pelvis with contrast revealed 2 thick-walled complex collections in the right hepatic lobe and the caudate lobe of the liver. Purulent aspirate grew A. xylosoxidans. In this report, we explore the characteristics of A. xylosoxidans and the associated infections it is known to cause as well as suggested treatments from previously reported cases.

The role of serum and urinary markers in predicting obstructing ureteral stones and reducing unjustified non-contrast computerized tomographic scans in emergency departments.

The reported yield of non-contrast computed tomography (NCCT) in assessing flank pain and obstructive urolithiasis (OU) in emergency departments (EDs) is only ~ 50%. We investigated the potential capability of serum and urinary markers to predict OU and improve the yield of NCCT in EDs. All consecutive ED patients with acute flank pain suggestive of OU and assessed by NCCT between December 2019 and February 2020 were enrolled. Serum white blood cells (WBC), C-reactive protein (CRP) and creatinine (Cr) levels, and urine dipstick results were analyzed for association with OU, and unjustified NCCT scan rates were calculated. NCCTs diagnosed OU in 108 of the 200 study patients (54%). The median WBC, CRP, and Cr values were 9,100/µL, 4.3mg/L, and 1mg/dL, respectively. Using ROC curves, WBC = 10,000/µL and Cr = 0.95mg/dl were the most accurate thresholds to predict OU. Only WBC ≥ 10,000/µL (OR = 3.7, 95% CI 1.6-8.3, p = 0.002) and Cr ≥ 0.95mg/dl (OR = 5, 95% CI 2.3-11, p < 0.001) were associated with OU. Positive predictive value and specificity for detecting OU among patients with combined WBC ≥ 10,000 and Cr ≥ 0.95 were 83% and 89%, respectively. Patients negative to the serum markers criteria underwent significantly more unjustified NCCTs (p = 0.03). The negative predictive value of the serum criteria for justified NCCT scanning was 81%. WBC and Cr may be valuable serum markers in predicting OU among patients presenting to EDs with acute flank pain. They may potentially reduce the number of unjustified NCCT scans in the ED setting.

Numerical assessment of morphological and hydraulic properties of moss, lichen and peat from a permafrost peatland

Abstract. Due to its insulating and draining role, assessing ground vegetation cover properties is important for high-resolution hydrological modeling of permafrost regions. In this study, morphological and effective hydraulic properties of Western Siberian Lowland ground vegetation samples (lichens, Sphagnum mosses, peat) are numerically studied based on tomography scans. Porosity is estimated through a void voxels counting algorithm, showing the existence of representative elementary volumes (REVs) of porosity for most samples. Then, two methods are used to estimate hydraulic conductivity depending on the sample's homogeneity. For homogeneous samples, direct numerical simulations of a single-phase flow are performed, leading to a definition of hydraulic conductivity related to a REV, which is larger than those obtained for porosity. For heterogeneous samples, no adequate REV may be defined. To bypass this issue, a pore network representation is created from computerized scans. Morphological and hydraulic properties are then estimated through this simplified representation. Both methods converged on similar results for porosity. Some discrepancies are observed for a specific surface area. Hydraulic conductivity fluctuates by 2 orders of magnitude, depending on the method used. Porosity values are in line with previous values found in the literature, showing that arctic cryptogamic cover can be considered an open and well-connected porous medium (over 99 % of overall porosity is open porosity). Meanwhile, digitally estimated hydraulic conductivity is higher compared to previously obtained results based on field and laboratory experiments. However, the uncertainty is less than in experimental studies available in the literature. Therefore, biological and sampling artifacts are predominant over numerical biases. This could be related to compressibility effects occurring during field or laboratory measurements. These numerical methods lay a solid foundation for interpreting the homogeneity of any type of sample and processing some quantitative properties' assessment, either with image processing or with a pore network model. The main observed limitation is the input data quality (e.g., the tomographic scans' resolution) and its pre-processing scheme. Thus, some supplementary studies are compulsory for assessing syn-sampling and syn-measurement perturbations in experimentally estimated, effective hydraulic properties of such a biological porous medium.

68Ga-labeled amphiphilic polymer nanoparticles for PET imaging of sentinel lymph node metastasis.

Precise diagnosis of lymph node metastasis is important for therapeutic regimen planning, prognosis analysis and probably better outcomes for cancer patients. In this work, 68Ga-labeled amphiphilic alternating copolymers nanoparticles with different rigid ligands were synthesized as positron emission tomography (PET) probes for lymph node metastasis imaging. The labeling efficiency and stability of nanoparticles was improved with increased rigidity of coordination unit. PU(68Ga-L-MDI-PEG) nanoparticles (PU(68Ga-L-MDI-PEG) NPs) with the strongest rigidity of coordination unit exhibited the lowest critical micelle concentration, the best 68Ga labeling efficiency and stability. During in vivo lymph node metastasis imaging, PU(68Ga-L-MDI-PEG) NPs led to different accumulations in normal lymph nodes (N-LN) and tumor metastasized sentinel lymph nodes (T-SLN), which resulted in different PET signal presentation, making it feasible to differentiate N-LN from T-SLN. In comparison, small molecule probe 68GaL had poor lymph node accumulation, not only making it difficult to find lymph nodes on PET/computed tomography scan, but also tough to distinguish N-LN from metastatic ones. Overall, this work provides a reference for design of 68Ga labeled polymeric nanoparticles with high chelation efficiency and stability, as sensitive PET probes for lymph node imaging.

TRAUMATIC BRAIN INJURY-INDUCED INFLAMMATION AND GASTROINTESTINAL MOTILITY DYSFUNCTION.

Background: Traumatic brain injury (TBI) is a significant cause of morbidity and mortality in the United States, with an annual cost of 60 billion dollars. There is evidence suggesting that in the post-TBI period, the gastrointestinal tract plays a central role in driving organ and immune dysfunction and may be the source of increased circulating proinflammatory mediators. In this study, we examined systemic inflammation and bacterial dysbiosis in patients who sustained a TBI with or without polytrauma. Using a mouse model of TBI, we further show how neuroinflammation after TBI is potentially linked to disruptions in gut homeostasis such as intestinal transit and inflammation. Methods: During a study of trauma patients performed from September 1, 2018, to September 1, 2019, at a single, level 1 trauma center, TBI patients aged 21 to 95 years were enrolled. Patients were categorized as TBI based on evidence of acute abnormal findings on head computed tomographic scan, which was a combination of isolated TBI and TBI with polytrauma. Blood and stool samples were collected between 24 h and 3 days after admission. Twelve plasma samples and 10 fecal samples were used for this study. Healthy control samples were obtained from a healthy control biobank. We examined systemic inflammation and bacterial changes in patients who sustained a TBI. In addition, TBI was induced in 9- to 10-week-old male mice; we assessed neuroinflammation, and intestine transit (motility) and bacterial changes 24 h after TBI. Results: When compared with healthy controls, TBI patients had increased systemic inflammation as evidenced by increased levels of IFN-γ and MCP-1 and a trend toward an increase of IL-6 and IL-8 ( P = 0.0551 and P = 0.0549), respectively. The anti-inflammatory cytokine, IL-4, was also decreased in TBI patients. Although there was a trend of an increase in copy number of Enterobacteriaceae and a decrease in copy number of Lactobacillus in both patients and mice after TBI, these trends were not found to be significantly different. However, TBI significantly increased the copy number of another potential pathogenic bacteria Bilophila wadsworthia in TBI patients compared with healthy controls. After a moderate TBI, mice had increased expression of TNF-α, IL-6 and IL-1β, CXCL1, s100a9, and Ly6G and decreased IL-10 in the brain lesion after TBI. This accompanied decreased transit and increased TNF-α in the small intestine of mice after TBI. Conclusions: Our findings suggest that TBI increases systemic inflammation, intestinal dysfunction, and neuroinflammation. More studies are needed to confirm whether changes in intestinal motility play a role in post-TBI neuroinflammation and cognitive deficit.

Geometric Deep Learning to Identify the Critical 3D Structural Features of the Optic Nerve Head for Glaucoma Diagnosis

To compare the performance of 2 relatively recent geometric deep learning techniques in diagnosing glaucoma from a single optical coherence tomographic (OCT) scan of the optic nerve head (ONH); and to identify the 3-dimensional (3D) structural features of the ONH that are critical for the diagnosis of glaucoma. Comparison and evaluation of deep learning diagnostic algorithms. In this study, we included a total of 2247 nonglaucoma and 2259 glaucoma scans from 1725 participants. All participants had their ONHs imaged in 3D with Spectralis OCT. All OCT scans were automatically segmented using deep learning to identify major neural and connective tissues. Each ONH was then represented as a 3D point cloud. We used PointNet and dynamic graph convolutional neural network (DGCNN) to diagnose glaucoma from such 3D ONH point clouds and to identify the critical 3D structural features of the ONH for glaucoma diagnosis. Both the DGCNN (area under the curve [AUC]: 0.97±0.01) and PointNet (AUC: 0.95±0.02) were able to accurately detect glaucoma from 3D ONH point clouds. The critical points (ie, critical structural features of the ONH) formed an hourglass pattern, with most of them located within the neuroretinal rim in the inferior and superior quadrant of the ONH. The diagnostic accuracy of both geometric deep learning approaches was excellent. Moreover, we were able to identify the critical 3D structural features of the ONH for glaucoma diagnosis that tremendously improved the transparency and interpretability of our method. Consequently, our approach may have strong potential to be used in clinical applications for the diagnosis and prognosis of a wide range of ophthalmic disorders.

Research on a novel digital tooth sectioning guide system for tooth sectioning during mandibular third molar extraction: An in vitro study

ObjectiveTo construct a novel portable tooth sectioning guide to improve the accuracy of mandibular third molar extraction. MethodsFirst, 72 samples of an identical 3D-printed double-rooted mandibular third molar were obtained and used in 36 mandibular models. Three different models were constructed (class B vertical, mesial, and horizontal impaction). Then, we made the tooth sectioning guides. mimicking clinical tooth sectioning conditions, two dental surgeons with different levels of experience used both the digital guided technique and the traditional empirical technique during surgery. Accuracy indicators, including apical deviation and angle deviation, were analyzed and compared on postoperative cone-beam computed tomographic scanning and via image reconstruction. Descriptive statistical analyses were performed. A p-value of 0.05 indicated statistically significant differences among the groups. ResultsOverall, the mean apical deviation of experienced/inexperienced operators using the conventional section technique was 1.120 mm (0.7 mm, 2.3 mm) and 1.54± 0.84 mm, respectively. Correspondingly, the mean apical deviation under the guided section technique was 0.28 mm (0.2 mm, 0.4 mm) and 0.32±0.16 mm, respectively. The mean angle deviations of experienced/inexperienced operators under the conventional section technique were 8.015° (3.5°, 10.5°) and 6.570° (5.5°, 14.9°). Correspondingly, the mean apical deviation using the guided section technique was 1.880° (0.4°, 2.9°) and 1.470° (0.7°, 3.1°), respectively. The conventional and guided techniques were significantly different (P < 0.001). ConclusionsIn the digital guide technique, sectioning is more predictable and accurate, and the success of the operation is achievable with different proficiencies among dental surgeons. Clinical SignificanceThis technique will not only reduce the difficulty of tooth extraction but also reduce the risk of damage to the surrounding soft and hard tissues, especially damage to the inferior alveolar nerve.

Facet joint violation after open and percutaneous posterior instrumentation: a comparative study

PurposePosterior instrumentation is the state-of-the-art surgical treatment for fractures of the thoracic and lumbar spine. Options for pedicle screw placement comprise open or minimally invasive techniques. Open instrumentation causes large approach related muscle detachment, which minimally invasive techniques aim to reduce. However, concerns of accurate pedicle screw placement are still a matter of debate. Beside neurological complications due to pedicle screw malplacement, also affection of the facet joints and thus motion dependent pain is known as a complication. The aim of this study was to assess accuracy of pedicle screw placement concerning facet joint violation (FJV) after open- and minimally invasive posterior instrumentation.MethodsA retrospective data analysis of postoperative computer tomographic scans of 219 patients (1124 pedicle screws) was conducted. A total of 116 patients underwent open screw insertion (634 screws) and 103 patients underwent minimally invasive, percutaneous screw insertion (490 screws). ResultsIn the lumbar spine (segments L3, L4, L5), there were significantly more and higher grade (open = 0.55 vs. percutaneous = 1.2; p = 0.001) FJV’s after percutaneously compared to openly inserted screws. In the thoracic spine, no significant difference concerning rate and grade of FJV was found (p > 0.56).ConclusionFJV is more likely to occur in percutaneously placed pedicle screws. Additionally, higher grade FJV’s occur after percutaneous instrumentation. However, in the thoracic spine we didn’t find a significant difference between open and percutaneous technique. Our results suggest a precise consideration concerning surgical technique according to the fractured vertebrae in the light of the individual anatomic structures in the preop CT.

Segmental Tracheomalacia in a Patient with a Persistent Air Leak.

Anesthesiology was consulted on an intubated 61-yr-old woman for difficulty ventilating secondary to a progressive air leak. A chest x-ray film that day (panel A) showed a circular area of lower density proximal to the endotracheal tube (ETT) tip. Computed tomographic scan revealed tracheal dilation of 4.1 cm in the axial plane (panel B) and its segmental nature in the sagittal plane (panel C) with (a) the ETT in situ at the level of the cuff and (b) the distal trachea measuring 1.5 cm. After the ETT cuff was deflated and advanced past the area of dilation, the air leak subsided. She later underwent a tracheostomy. Primary, or congenital, causes of tracheal dilation include polychondritis, idiopathic, and Mounier-Kuhn syndrome. Secondary, or acquired, causes are more common and include trauma, emphysema, chronic inflammation, chronic external compression of the trachea, and vascular rings.1 Tracheal dilation due to prolonged intubation is typically segmental and less than 3.0 cm, and tracheal mucosal changes are common.2 Chest x-ray film can be used for the diagnosis of static dilation, especially in a mechanically ventilated patient where the area of dilation may exist at the level of the endotracheal tube cuff. Tracheobronchoscopy through the ETT in situ may not reveal the tracheal dilation and mucosal changes because the tip of the ETT is distal to the segment of dilated trachea. A prompt computed tomographic scan would be valuable to guide management and can aid in the detection of dynamic airway collapse, tracheocele, or tracheal diverticula.3 This image shows an extreme case of tracheal dilation that exceeds 3.0 cm.Support was provided solely from institutional and/or departmental sources.The authors declare no competing interests

Biomechanical responses of the human lumbar spine to vertical whole-body vibration in normal and osteoporotic conditions

BackgroundThe prevalence of osteoporosis is continuing to escalate with an aging population. However, it remains unclear how biomechanical behavior of the lumbar spine is affected by osteoporosis under whole-body vibration, which is considered a significant risk factor for degenerative spinal disease and is typically present when driving a car. Accordingly, the objective of this study was to compare the spine biomechanical responses to vertical whole-body vibration between normal and osteoporotic conditions. MethodsA three-dimensional finite-element model of the normal human lumbar spine-pelvis segment was developed using computed tomographic scans and was validated against experimental data. Osteoporotic condition was simulated by modifying material properties of bone tissues in the normal model. Transient dynamic analyses were conducted on the normal and osteoporotic models to compute deformation and stress in all lumbar motion segments. FindingsWhen osteoporosis occurred, vibration amplitudes of the vertebral axial displacement, disc bulge, and disc stress were increased by 32.1–45.4%, 25.7–47.1% and 23.0–42.7%, respectively. In addition, it was found that for both the normal and osteoporotic models, the response values (disc bugle and disc stress) were higher in L4–L5 and L5–S1 intervertebral discs than in other discs. InterpretationOsteoporosis deteriorates the effect of whole-body vibration on lumbar spine, and the lower lumbar segments might have a higher likelihood of disc degeneration under whole-body vibration.

Colonoscopy following the positron emission tomography/computed tomography scan in patients with incidental colorectal uptake: what is the most effective management?

Colorectal cancer is one of the most common malignancies. Survival rates are directly related to the stage of cancer at the time of diagnosis, emphasizing the value of early diagnosis. Positron emission tomography with 18F-fluorodeoxyglucose is the gold standard imaging technique in staging, monitoring after treatment, and follow-up. We aimed to assess the importance of incidental 18F-fluorodeoxyglucose uptake by colon and rectum in positron emission tomography-computed tomography imaging to determine a significant cutoff value for further investigation using colonoscopy and histopathological assessment. We performed a retrospective analysis of patients with both 18F-fluorodeoxyglucose-positron emission tomography/computed tomography scan and colonoscopy during 1 year and included the cases who had undergone a colonoscopy within 3 months following the positron emission tomography/computed tomography scan due to an incidental positive finding. Patients with a diagnosed colorectal malignancy or with a history of previous colorectal operations were excluded. A total of 81 patients were included in this study. Among 81 colonoscopic evaluations, histopathology revealed malignancy in 8 patients, and the prevalence of incidental colorectal cancer 18F-fluorodeoxyglucose uptake was found to be 9.87%. SUVmax was found to be significantly related to malignancy and other colonoscopic findings (p<0.001). SUVmax cutoff value to suggest colorectal cancer was found to be median [7.9 (4.1-12.7)] (p<0.001). Regarding the studies determining a significant cutoff value, incidental colonic 18F-fluorodeoxyglucose uptake on positron emission tomography/computed tomography should lead the clinician to further investigation with colonoscopic biopsy, although the cutoff values for SUVmax are not certain and different in almost every published study, and negative positron emission tomography.computed tomography findings should not completely rule out malignancy, especially in high-risk patients.

Surgical Management of Cervical Myelopathy: Current Algorithm

Cervical myelopathy (CM) is a progressive disorder associated with a varied spectrum of etiological factors. Cervical spondylotic myelopathy (CSM) encompasses two-thirds of the cases of CM, while ossified posterior longitudinal ligament (OPLL) and ossified ligamentum flavum (OLF) are significant regional etiological factors. Microvascular disruption, resulting from repetitive dynamic compression or static pressure to the spinal cord, is attributed as a primary pathophysiological mechanism for CM. Magnetic resonance imaging (MRI) is the investigation of choice to assess the spinal cord. Lateral cervical radiographs are crucial for lordosis assessment, and tomographic scans (CT) can delineate the extent of OPLL and OLF. Non-surgical treatment is usually not successful once the patient develops progressive myelopathy. Anterior cervical procedures are ideal for one or two level disc-osteophytes complexes or in patients with kyphotic cervical alignment. Laminoplasty is an effective motion-preserving option in patients with adequate cervical lordosis. Laminectomy or laminoplasty and fusion are optimal for patients with significant preoperative neck pain. Posterior surgery is preferred over anterior surgery for CM involving three or more levels. Older age at presentation, longer duration of symptoms, and severity of pre-operative symptoms are adverse prognostic factors. Progressive cervical myelopathy is a surgical disease, and early intervention is rewarded with better outcomes. Keywords: Cervical myelopathy, Cervical spondylotic myelopathy, OPLL, OLF, Laminoplasty, Laminectomy, ACDF, Cervical corpectomy.

Редкий клинический случай инородного тела гортаноглотки

Foreign bodies of the larynx, pharynx, and laryngopharynx are quite common cases in otorhinolaryngological practice. At the same time, they make up a significant proportion of emergency surgical interventions among other ENT pathologies. Foreign bodies can damage the walls of the organ, causing dangerous complications. Diagnosis is usually based on data from laryngoscopy or endoscopy. However, in rare cases, additional research methods, such as computed tomography, are required. With deep localization of foreign bodies of the laryngopharynx, their removal is difficult, as a result of which they resort to surgical intervention. This article is a description of a foreign body (chicken bone) of unusual localization in a 57-year-old female patient. The thin sharp bone migrated entirely into the soft tissues of the left pyriform sinus, which was diagnosed by computed tomography. Since it was not possible to remove the foreign body under the control of laryngoscopy, it was decided to perform a left-sided colotomy. After a successful operation, the patient’s condition was satisfactory, the wound healed by primary intention, the sutures were removed on the seventh day after the operation. The article presents the data upon admission of the patient as well as the course of treatment illustrated by the picture of changes presented on tomography scans.

Wavelength encoded single-shot high-spatiotemporal resolution all-optical probe

The laser probe is one of the main techniques for capturing ultrafast dynamic processes and has extensive applications in fields such as plasma physics, photochemistry, and biomedical science. In this work, a time-wavelength encoded optical probe generation scheme is proposed, which uses cascaded frequency doubling crystals with different phase-matching angles and independent delay lines to achieve time-wavelength encoding. This method offers single-shot high-spatiotemporal resolution, high frame rate, and a wide range of adjustable time windows. The temporal resolution of the optical probe depends on the pulse width of the second harmonic, which can be adjusted by changing the phase-matching angle of the frequency-doubling crystal. The time window of the optical probe is only related to the change in the delay line, which can be adjusted by changing the length of the delay line. Therefore, the time resolution and time window of the optical probe are independent of each other. An optical probe generation system is constructed with 247 fs temporal resolution, 4 μm spatial resolution, 4.05 THz maximal frame rate, and an adjustable time window from sub-picosecond to 3 ns. The three-dimensional spatiotemporal evolution process of plasma filaments is captured within a single shot by using the optical probe. The experimental results show that the ionization front of the plasma propagates forward at a velocity of &lt;inline-formula&gt;&lt;tex-math id="M2"&gt;\begin{document}$ {\left(2.963\pm 0.024\right)\times 10}^{8}\;{\rm{m}}/{\rm{s}} $\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="22-20230727_M2.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="22-20230727_M2.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt;, which is consistent with the theoretical prediction. This demonstrates the feasibility of using the probe for capturing ultrafast events. In the part of discussion, we analyze that the key parameters of the optical probe can reach a maximum frame rate of 35.7 THz, a maximum time resolution of 28 fs, and a time window range that can be adjusted from hundreds of femtoseconds to tens of nanoseconds. Finally, the optimal design parameters of the optical probe are given for different application scenarios. The optical probe generation scheme has good scalability and versatility, and can be combined with any wavelength decoding device, diffraction imaging, holographic imaging, tomography scanning, and other technologies. The high spatiotemporal resolution of the optical probe and the independent adjustability of its parameters provide a feasible solution for single-shot high spatiotemporal resolution captures of ultrafast dynamic processes on a multiple time scale.

Ex Vivo Evaluation of a Minimally Invasive Approach for Cochlear Implant Surgery.

Drilling a minimally invasive access to the inner ear is a demanding task in which a computer-assisted surgical system can support the surgeon. Herein, we describe the design of a new micro-stereotactic targeting system dedicated to cochlear implant (CI) surgery and its experimental evaluation in an ex vivo study. The proposed system consists of a reusable, bone-anchored reference frame, and a patient-specific drilling jig on top of it. Individualization of the jig is simplified to a single counterbored hole drilled out of a blank. For accurate counterboring, the setup includes a manufacturing device for individual positioning of the blank. The system was tested in a preclinical setting using twelve human cadaver donors. Cone beam computed tomograph (CBCT) scans were obtained and a drilling trajectory was planned pointing towards the basal part of the cochlea. The surgical drill was moved forward manually and slowly while the jig constrained the drill along the predetermined path. Drilling could be performed with preservation of facial nerve in all specimens. The mean error caused by the system at the target point in front of the cochlea was 0.30 mm ± 0.11 mm including an inaccuracy of 0.09 mm ± 0.03 mm for counterboring the guiding aperture into the jig. Feasibility of the proposed system to perform a minimally invasive posterior tympanotomy approach was shown successfully in all specimens. First evaluation of the new system in a comprehensive ex vivo study demonstrating sufficient accuracy and the feasibility of the whole concept.

Surgical Management and Outcomes of Patients with Idiopathic Peroneal Spastic Flatfoot: A Retrospective Case Series.

Although tarsal coalition represents the most common cause of peroneal spastic flatfoot, its existence cannot be verified in several cases. In some patients with rigid flatfoot, no cause can be detected after clinical, laboratory, and radiologic examination, and the condition is called idiopathic peroneal spastic flatfoot (IPSF). This study aimed to present our experience with surgical management and outcomes in patients with IPSF. Seven patients with IPSF, who were operated on between 2016 and 2019, and followed for at least 12 months were included, whereas those with known causes, such as tarsal coalition or other causes (eg, traumatic) were excluded. All patients were followed up for 3 months with botulinum toxin injection and cast immobilization as a routine protocol, and clinical improvement was not achieved. The Evans procedure and grafting with tricortical iliac crest bone graft in five patients and subtalar arthrodesis in two patients were performed. The American Orthopaedic Foot and Ankle Society ankle-hindfoot scale scores and Foot and Ankle Disability Index scores were obtained preoperatively and postoperatively from all patients. On physical examination, all feet manifested rigid pes planus with varying degrees of hindfoot valgus and limited subtalar motion. Overall, the mean American Orthopaedic Foot and Ankle Society and Foot and Ankle Disability Index scores significantly increased from 42 (range, 20-76) and 45 (range, 19-68) preoperatively (P = .018) to 85 (range, 67-97) and 84 (range, 67-99) (P = .043) at the final follow-up, respectively. No major intraoperative or postoperative complications were observed in any of the patients. All computed tomographic and magnetic resonance imaging scans revealed no evidence of tarsal coalitions in any of the feet. All radiologic workups failed to demonstrate secondary signs of fibrous or cartilaginous coalitions. Operative treatment seems to be a good option in the treatment of patients with IPSF who do not benefit from conservative treatment. In the future, it is recommended to investigate the ideal treatment options for this group of patients.

Limbal Stem Cell Deficiency: A Review Focusing on Staging, Diagnostic and Treatment Modalities

The cornea being a transparent tissue acts as a refractive surface as well as a protective barrier of the eye. The corneal epithelium is being continuously replaced and renewed by the Limbal Stem Cells (LSC). The turnover of corneal epithelium is brought about by asymmetrical differentiation and self-renewal of LSCs, their migration to the cornea and desquamation of current corneal epithelium. LSC are undifferentiated cells that acts as progenitors of corneal epithelium and maintains corneal homeostasis. LSC resides in its own microenvironment known as LSC niche, which are capable of sustaining these tissue regenerating cells. Any intrinsic factors (e.g., toxic epidermal necrolysis or mucous membrane pemphigoid), extrinsic factors (e.g., thermal burns, radiations, chemical burns) or genetic defects (e.g., aniridia) cause impairment of LSC or its niche leading to Limbal Stem Cell Deficiency (LSCD). LSCD is associated with invasion of cornea by conjunctival epithelium, corneal opacity, and visual impairment. The diagnostic modality of LSCD includes fluorescein staining and slit lamp examination, impression cytology, confocal scanning and anterior chamber optical coherence tomography. The staging of LSCD is important for deciding the treatment modalities. In LSCD, the most common treatment modality includes LSC transplant from a healthy eye. Non LSC transplantation techniques are being used to prevent allograft rejection. In this review article, the authors aim to summarise the existing knowledge of the aetiology, staging and treatment modalities of LSCD.

Horseshoe retinal tear: factors that determine the risk of developing rhegmatogenous retinal detachment

This study aimed to determine the main risk factors for RRD development based on the analysis of the condition of vitreoretinal interface in the area of horseshoe tears, both isolated and those that resulted in retinal detachment. A total of 88 patients with horseshoe retinal tears (43 patients with RRD due to the horseshoe tear and 45 with isolated horseshoe tears) were included in the study. All patients underwent wide-field multispectral laser scanning and optical coherence tomography to determine the shape of the horseshoe tear and the extent of vitreoretinal adhesion (VRA). Cluster analysis was used to differentiate horseshoe tears by shape. Spearman's correlation analysis was used to identify the relationship between the shape of the horseshoe tear and localization of VRA. Spearman's correlation analysis revealed a strong negative correlation between the length-to-width ratio of the horseshoe tear and the extent of VRA. Cluster analysis helped determine four shapes of horseshoe tears, each corresponding to a certain localization of VRA. Analysis of RRD risk, depending on the characteristics of the horseshoe tear, showed that the most significant risk factor for the development of RRD is the presence of a horseshoe tear with width greater than its length, which is characterized by a larger VRA area. The study established that the larger the horseshoe tear width and the smaller its length, the larger the VRA area and, consequently, the higher the risk of RRD development. Horseshoe retinal tears with a length-to-width ratio of less than 1/1 are the most dangerous in terms of RRD risk, which is important to consider when selecting the treatment tactics.

Anatomical feasibility of fenestrated stent graft to treat complex abdominal aortic aneurysms from a Korean single institute database.

This study aims to investigate the feasibility of Zenith Fenestrated AAA Endovascular Graft (Z-FEN, Cook Medical) from a single Korean institution database by evaluating the vascular anatomy of Korean abdominal aortic aneurysm (AAA) patients with hostile aortic neck. This is a retrospective study on patients with AAA who underwent endovascular aortic repair (EVAR) and open surgery repair between January 2012 and December 2021 (n = 211). The anatomic characteristics of the aortic neck were evaluated using 3-dimensional reconstructed computed tomographic scans. For the juxtarenal AAA patients (n = 39), feasibility of fenestrated stent graft was evaluated under the protocol of fenestrated EVAR. For those who were not suitable for the application of Z-FEN, the reasons for unsuitability were analyzed. Among 211 AAA patients, 108 patients (51.2%) had complex aortic neck, and 39 (18.5%) had insufficient aortic neck length (<15 mm) for conventional EVAR. Of the 39 patients with juxtarenal AAAs, 13 (33.3%) were determined feasible for Z-FEN. Twenty-six patients (66.7%) were noncandidate for Z-FEN due to severe neck angulation, short aortic neck length, inadequate iliac artery anatomy, large aortic neck diameter, and severe calcification and thrombosis. Proximal aortic neck length of the non-feasible group was significantly shorter than that of the feasible group (P = 0.002). Z-FEN was applicable to 33.3% of the juxtarenal AAA patients. As recent studies confirm, the effectiveness and safety of fenestrated EVAR, Z-FEN can be an option for AAA patients with short aortic neck.