Exploring the science of thinking independently together: Faraday Discussion Volume 204 - Complex Molecular Surfaces and Interfaces, Sheffield, UK, July 2017.

The 2017 Faraday Discussion on Complex Molecular Surfaces and Interfaces brought together theoreticians and experimentalists from both physical and chemical backgrounds to discuss the relevant applied and fundamental research topics within the broader field of chemical surface analysis and characterization. Main discussion topics from the meeting included the importance of "disordered" two-dimensional (2D) molecular structures and the utility of kinetically trapped states. An emerging need for new experimental tools to address dynamics and kinetic pathways involved in self-assembled systems, as well as the future prospects and current limitations of in silico studies were also discussed. The following article provides a brief overview of the work presented and the challenges discussed during the meeting.

Three-dimensional kinematic stress magnetic resonance image analysis shows promise for detecting altered anatomical relationships of tissues in the cervical spine associated with painful radiculopathy.

For some patients with radiculopathy a source of nerve root compression cannot be identified despite positive electromyography (EMG) evidence. This discrepancy hampers the effective clinical management for these individuals. Although it has been well-established that tissues in the cervical spine move in a three-dimensional (3D) manner, the 3D motions of the neural elements and their relationship to the bones surrounding them are largely unknown even for asymptomatic normal subjects. We hypothesize that abnormal mechanical loading of cervical nerve roots during pain-provoking head positioning may be responsible for radicular pain in those cases in which there is no evidence of nerve root compression on conventional cervical magnetic resonance imaging (MRI) with the neck in the neutral position. This biomechanical imaging proof-of-concept study focused on quantitatively defining the architectural relationships between the neural and bony structures in the cervical spine using measurements derived from 3D MR images acquired in neutral and pain-provoking neck positions for subjects: (1) with radicular symptoms and evidence of root compression by conventional MRI and positive EMG, (2) with radicular symptoms and no evidence of root compression by MRI but positive EMG, and (3) asymptomatic age-matched controls. Function and pain scores were measured, along with neck range of motion, for all subjects. MR imaging was performed in both a neutral position and a pain-provoking position. Anatomical architectural data derived from analysis of the 3D MR images were compared between symptomatic and asymptomatic groups, and the symptomatic groups with and without imaging evidence of root compression. Several differences in the architectural relationships between the bone and neural tissues were identified between the asymptomatic and symptomatic groups. In addition, changes in architectural relationships were also detected between the symptomatic groups with and without imaging evidence of nerve root compression. As demonstrated in the data and a case study the 3D stress MR imaging approach provides utility to identify biomechanical relationships between hard and soft tissues that are otherwise undetected by standard clinical imaging methods. This technique offers a promising approach to detect the source of radiculopathy to inform clinical management for this pathology.

Fluoroscopic and CT fistulography of the first branchial cleft.

We present an unusual case of a complete first branchial cleft fistula communicating between the external auditory canal and the skin near the angle of the mandible. CT and fluoroscopic fistulography were used to establish the presence and course of the tract and to assist in surgical planning. The embryology and classification of first branchial cleft anomalies are discussed, with emphasis on the impact of imaging.

The effect of ankle ligament damage and surgical reconstructions on the mechanics of the ankle and subtalar joints revealed by three-dimensional stress MRI.

Common image-based diagnostic techniques used to detect ankle ligament injuries or the effects of those injuries (e.g., mechanical instability) include magnetic resonance imaging (MRI) and stress radiography. Each of these techniques has limitations. The interpretation of the results obtained through stress radiography, a two-dimensional technique, is highly controversial. MRI can facilitate visualization of soft tissue, but three-dimensional visualization of the full length of the ligaments or detecting partial ligament damage is difficult. This work is part of a long-term study aimed at improving the diagnostic ability of MRI by utilizing it not only to visualize the ligaments but also to detect the mechanical instability produced at the ankle and subtalar joints due to ligament damage. The goal of the present study was to evaluate the ability of a previously developed technique called 3D stress MRI (sMRI) to detect in vitro the effect of damage to the lateral collateral ligaments and the stabilizing effect produced by two common surgical reconstruction techniques. MRI data were collected from eight cadaver limbs in a MR compatible ankle-loading device in neutral, inversion, and anterior drawer. Each specimen was tested intact, after cutting the anterior talo-fibular ligament followed by the calcaneo-fibular ligament and after applying two reconstructions. Ligament injuries produced significant changes in the response of the ankle and subtalar joints to load as detected by the 3D stress MRI technique. Both surgical procedures restored mechanical stability to the joints but they differed in the amount and type of stabilization achieved. We concluded that 3D sMRI can extend the diagnostic power of MRI from the current practice of slice-by-slice visualization to the assessment of mechanical function, the compromise in this function due to injury, and the effects of surgery.

Mechanics of the ankle and subtalar joints revealed through a 3D quasi-static stress MRI technique.

A technique to study the three-dimensional (3D) mechanical characteristics of the ankle and of the subtalar joints in vivo and in vitro is described. The technique uses an MR scanner compatible 3D positioning and loading linkage to load the hindfoot with precise loads while the foot is being scanned. 3D image processing algorithms are used to derive from the acquired MR images bone morphology, hindfoot architecture, and joint kinematics. The technique was employed to study these properties both in vitro and in vivo. The ankle and subtler joint motion and the changes in architecture produced in response to an inversion load and an anterior drawer load were evaluated. The technique was shown to provide reliable measures of bone morphology. The left-to-right variations in bone morphology were less than 5%. The left-to-right variations in unloaded hindfoot architecture parameters were less than 10%, and these properties were only slightly affected by inversion and anterior drawer loads. Inversion and anterior drawer loads produced motion both at the ankle and at the subtalar joint. In addition, high degree of coupling, primarily of internal rotation with inversion, was observed both at the ankle and at the subtalar joint. The in vitro motion produced in response to inversion and anterior drawer load was greater than the in vivo motion. Finally, external motion, measured directly across the ankle complex, produced in response to load was much greater than the bone movements measured through the 3D stress MRI technique indicating the significant effect of soft tissue and skin interference.

The potential risk of carotid injury in cochlear implant surgery.

BACKGROUND: The advent of cochlear implantation has revolutionized the options afforded to the deaf population. With the increase in the prevalence of this procedure have come larger experiences in the associated technical challenges and complications. RESULTS: We present the evaluation and management of a patient with an unusual complication of improper placement of the implant electrode into the carotid canal and its management. We discuss the anatomy of the carotid artery and its proximity to the cochlea to emphasize the potential risk to this large vessel. CONCLUSIONS: Damage to the carotid canal and the carotid artery is a potential risk of cochlear implant surgery. When available, we recommend intraoperative electrical testing of the cochlear implant be performed. If there is doubt as to the placement of the electrode, a radiograph should be obtained before the patient is taken out of the operating room to avoid this complication.

Histopathologic study of temporal bone and eustachian tube in oculoauriculovertebral spectrum.

Bilateral temporal bone specimens from a 21-month-old girl and a left temporal bone-eustachian tube (ET) specimen from a full-term female newborn, both with oculoauriculovertebral spectrum, were studied histopathologically. The external and middle ears demonstrated severe anomalies, similar to those of previous reports describing the histopathologic findings of this syndrome. In addition, despite having a normal auricle, the 21-month-old child had bilateral hypoplastic cochleas as seen in Mondini dysplasia. The newborn had several anomalies of the ET, including a widely opened cartilaginous portion of the ET lumen and absence of the lateral lamina of the ET cartilage. We discuss the implications of the observed anomalies with regard to developmental and clinical issues.

Temporal bone histopathological study of Noonan syndrome.

Four temporal bone specimens, obtained from three individuals 1--6 years of age with Noonan syndrome (NS), were studied histopathologically. All four specimens were accompanied by similar inner ear abnormalities including the reduced number of spiral ganglion cells, enlarged lateral semicircular canal, and dislocated endolymphatic sac and vestibular aqueduct. The mean population of spiral ganglion cells (15,699 cells) was approximately half of those (32,978 cells) in four age-matched control cases. In addition, they had several middle ear abnormalities including the remaining mesenchyme and dehiscence of the facial canal. To our knowledge, this is the first report to describe the histopathological temporal bone findings in patients with NS. We discuss the implications of the observed abnormalities with regard to clinical issues.

An in vivo analysis of the motion of the peri-talar joint complex based on MR imaging.

The purpose of this work is to characterize the three-dimensional (3-D) motion of the peritalar joint complex in vivo using magnetic resonance imaging (MRI). Each image data set utilized in this study is made of 60 longitudinal MR slices of the foot in each of eight positions from extreme pronation to extreme supination. We acquired and analyzed ten such data sets from normal subjects, seven data sets from pathological joints and two postoperative data sets. We segmented and formed the surfaces of the calcaneus, talus, cuboid and navicular from all data sets. About 30 geometrical parameters are computed for each joint in each position. The results present features of normal motion and show how normal and abnormal motion can be distinguished. They also show the consequences of surgery on the motion. This non- invasive method offers a unique tool to characterize and quantify the 3-D motion of the rearfoot in vivo from MR images.

Pennation angles of the intrinsic muscles of the foot.

As mathematical models of the musculoskeletal system become increasingly detailed and precise, they require more accurate information about the architectural parameters of the individual muscles. These muscles are typically represented as Hill-type models, which require data on fiber length, physiological cross-sectional area (PCSA) and pennation angle. Most of this information for lower limb muscles has been published, except for data on the pennation angle of the intrinsic muscles of the foot. Each (n=20) intrinsic muscle of three human feet was dissected free. The dorsal and plantar surfaces were photographed and a digitized color image was imported into Abobe Photoshop. The muscles were divided into "anatomical units". For each anatomical unit (n=26), a line was drawn along the tendon axis and a number of other lines were drawn along individual muscle fibers. The angle between the tendon line and each fiber line was defined as the pennation angle of that fiber. By visual inspection, an effort was made to take measurements such that they represented the distribution of fibers in various parts of the muscle. Although some individual muscles had higher or lower pennation angles, when averaged for all specimens, the second dorsal interosseous had the smallest pennation angle (6.7+/-6.81 degrees) while the abductor digiti minimi had the largest (19.1+/-11.19 degrees). Since the cosines of the angles range from 0.9932 to 0.9449, the effect of the pennation angle on the force generated by the muscle was not great.

Imaging of tinnitus: a review.

Tinnitus, a buzzing or ringing in the ear, may be pulsatile or continuous (nonpulsatile). The distinction, with a detailed clinical evaluation, determines the most appropriate imaging study. Pulsatile tinnitus suggests a vascular neoplasm, vascular anomaly, or vascular malformation. Most of the neoplasms are glomus tympanicum and glomus jugulare tumors. Vascular anomalies may cause pulsatile tinnitus, but the mechanism is unknown, and another (treatable) cause should be sought. Most neoplasms and anomalies are best seen on bone algorithm computed tomographic (CT) studies. Dural vascular malformations are often elusive on all cross-sectional imaging studies; conventional angiography may be necessary to make this diagnosis. Flow-sensitive magnetic resonance (MR) images show vascular loops compressing the eighth cranial nerve. Carotid dissections, aneurysms, atherosclerosis, and fibromuscular dysplasia can be identified on both MR imaging or MR angiographic studies and CT or CT angiographic studies. Otosclerosis and Paget disease are CT diagnoses. Benign intracranial hypertension often has no abnormal imaging findings. For patients with nonpulsatile tinnitus, MR imaging is the study of choice to exclude a vestibular schwannoma or other neoplasm of the cerebellopontine angle cistern. Multiple sclerosis and a Chiari I malformation are rare causes of pulsatile tinnitus, also best seen on MR studies. Many patients with tinnitus have no abnormal imaging findings.

Squamous cell carcinoma of the external auditory canal: an evaluation of a staging system.

OBJECTIVE: The study was conducted to review a staging system proposed by the University of Pittsburgh for temporal bone cancer and to evaluate survival status according to stage, treatment, and certain prognostic factors. STUDY DESIGN: The study was a retrospective case review. SETTING: The study was conducted at a tertiary care medical center and specialty hospital. PATIENTS: Thirty-two patients with primary squamous cell carcinoma of the external auditory canal were studied. INTERVENTION: All patients underwent surgery of the temporal bone. Radiotherapy was given depending on tumor stage and histopathologic findings. MAIN OUTCOME MEASURES: The 2-year survival rates of patients undergoing surgical resection with or without adjuvant radiotherapy. RESULTS: The 2-year survival rates for primary squamous cell carcinoma of the temporal bone were as follows: T1 lesions 100%, T2 80%, T3 50%, and T4 7%. Survival for T3 tumors was 75% with postoperative radiotherapy, compared with 0% with surgery alone. CONCLUSIONS: The 2-year survival data directly correlated with the staging system. The use of adjuvant radiotherapy increased survival rate in patients with a T3 lesion.

Histopathologic study of the human eustachian tube and its surrounding structures following irradiation for carcinoma of the oropharynx.

OBJECTIVE: To describe a histopathologic analysis of a human temporal bone demonstrating patulous changes of the eustachian tube (ET) and its surrounding structures following radiation therapy. DESIGN: Retrospective histopathologic case review and comparison with an age-matched control. SETTING: Elizabeth McCullough Knowles Otopathology Laboratory, University of Pittsburgh School of Medicine, Pittsburgh, Pa. RESULTS: A widened patulous ET was verified by demonstrating fibrous tissue replacement of the surrounding supporting structures related to the ET. The ET lumen was patulous and wider than the control case. Ostmann fatty tissue, the levator veli palatini muscle, and submucosal glands around the ET cartilage were replaced by dense connective tissue. CONCLUSION: This is the first histopathologic report, to our knowledge, demonstrating the effects on the ET lumen and supporting structures following acute weight loss, possible tumor infiltration, and radiation changes for carcinoma of the oropharynx.

A characterization of the geometric architecture of the peritalar joint complex via MRI: an aid to the classification of foot type.

The purpose of this work is to study the architecture of the rearfoot using in vivo MR image data. Each data set used in this study is made of sixty sagittal slices of the foot acquired in a 1.5-T commercial GE MR system. We use the live-wire method to delineate boundaries and form the surfaces of the bones. In the first part of this work, we describe a new method to characterize the three-dimensional (3-D) relationships of four bones of the peritalar complex and apply this description technique to data sets from ten normal subjects and from seven pathological cases. In the second part, we propose a procedure to classify feet, based on the values of these new architectural parameters. We conclude that this noninvasive method offers a unique tool to characterize the 3-D architecture of the feet in live patients, based on a set of new architectural parameters. This can be integrated into a set of tools to improve diagnosis and treatment of foot malformations.