The neurocranium of the Paleozoic ‘chipmunk ray’ Tamiobatis vetustus Eastman, 1897. A brief history of research and new morphological observations based on computerized tomography

The course of the intraorbital part of the optic nerve, as demonstrated on anatomic sections in various planes, is correlated with the appearance of the nerve in computed tomographic (CT) images. Discrepancies between the anatomic and CT appearance are analyzed and discussed. Since the optic nerve has a sinuous course in both the horizontal and vertical planes, no thin axial or sagittal section can be entirely parallel to the nerve. Any section will transsect the optic nerve obliquely, leading to an apparent hypodensity or "thinning" of certain segments as shown on CT. The appearance of the course of the nerve on reformatted CT images depends on the plane of the original CT section. Computed tomograms that are obtained with the eye in primary position do not allow reliable judgments regarding the course and size of the optic nerve.

This is a retrospective analysis. To investigate and compare the sensitivities of computed tomography (CT) and magnetic resonance myelography (MRM) in the presurgical diagnosis of foraminal or extraforaminal entrapment of the L5 nerve. CT is more clinically available than MRM. Foraminal or extraforaminal entrapment at the lumbosacral junction may cause L5 radiculopathy but is difficult to diagnose. Asymmetric enlargement of the anterior primary division (APD) of the L5 nerve on preoperative CT and dorsal root ganglion (DRG) swelling and abnormal L5 nerve course on MRM coronal images have been examined in cases of foraminal or extraforaminal L5 nerve entrapment, but have not been compared directly. Ninety-five patients (mean age 63 y; 28-85 y) with L5 nerve entrapment at the lumbosacral junction who underwent preoperative CT and MRM, and microsurgical decompression by a single surgeon (K.-H.M.) from January 2010 to June 2014 were included. Symptomatic sites were diagnosed by confirming L5 nerve entrapment intraoperatively. Two spinal surgeons independently compared the bilateral APD diameters of the L5 nerve on CT and the L5 nerve courses and DRG swelling on MRM coronal images. The interobserver agreement of asymmetric APD swelling on CT and abnormal nerve course and DRG swelling on MRM were excellent (κ=0.808, 0.811, and 0.849, respectively), and the sensitivities were 81%, 84%, and 82% on the right, and 86%, 92%, and 90% on the left sides, respectively. There was no statistically significant difference in the sensitivity between APD swelling on CT and an abnormal nerve course or DRG swelling on MRM on the right (P=1.000 and 0.789) and left (P=0.727 and 1.000) sides, respectively. CT has comparable sensitivity to MRM for the presurgical diagnosis of L5 nerve entrapment at the lumbosacral junction. Level II.

Posterior tympanotomy is a well-known otologic procedure that allows surgeons access to the middle ear cavity. During posterior tympanotomy the surgeon can approach the round window niche and promontory, where a cochleostomy is carried out for cochlear implant electrode array insertion. The mastoid segment of the facial nerve and the chorda tympani nerve could be injured in cases of narrow facial recess or inadequate posterior tympanotomy. With the image reconstruction in an oblique sagittal plane and curve reconstructions, the whole tympanic and mastoid segments of the facial nerve can be visualized in just one image. It is necessary to preoperatively estimate both the facial nerve status and the anatomical relationships between the facial recess and the round window, this may reduce the risk of facial nerve injury and influence the decision on which side to implant, which approach to use and whether to enter the cochlea via cochleostomy or round window membrane route. The aim of our study is to evaluate the facial nerve (course and anomalies), visibility of the round window membrane and the width of posterior tympanotomy before cochlear implantation by using oblique sagittal cuts CT scan temporal bone. A prospective study; done on 18 consecutive patients with severe to profound sensorineural hearing loss who are candidates for cochlear implantation in Ain Shams University Hospitals during years 2011 & 2012. We focused on oblique sagittal cut CT scan & its role to evaluate the course of facial nerve, posterior tympanotomy width and visibility of the round window. We tried to make a statistical correlation between CT scan and intraoperative findings. Statistically significant positive correlation between posterior tympanotomy width and 2nd genu angle, distance from facial bony canal to round window and distance from facial nerve to round window. The mean distance from facial bony canal to round window was longer in operatively viewed round window than non-viewed window (4.7 and 4.4 mm respectively) (P < 0.05). The mean distance from facial nerve to round window was longer in operatively viewed round window membrane than non-viewed window (5.9 and 5.5 mm respectively) (P < 0.05). The mean width of posterior tympanotomy was wider in operatively viewed round window niche than non-viewed window niche (3.1 and 3.0 mm respectively) (P < 0.01). Oblique sagittal cuts CT scan temporal bone is very helpful preoperative radiological tool for evaluation of the facial nerve course and anatomical factors that may determine the field of view or the accessibility of the posterior tympanotomy for either cochleostomy or round window membrane approach. Other approaches can be used with more safety when the position of the facial nerve prevents an adequate posterior tympanotomy.

For decades, dual-energy imaging has been used for tissue differentiation with several x-ray–based imaging modalities, exploiting the fact that the tissues in the human body show different absorption characteristics when penetrated with different x-ray spectra, spectra that are typically generated by different kV settings of the x-ray tube. Recently, dual-source computed tomography (CT) with 2 x-ray tubes and 2 detector arrays mounted in the same gantry has become available.1 After experience with earlier experimental prototypes, this dual-source CT for the first time enables the clinical acquisition of dual-energy CT studies simultaneously with a single scan. We used a dual-source CT scanner (Definition, Siemens, Forchheim, Germany) in dual-energy mode for performing coronary CT angiography in a 74-year–old woman with suspected coronary artery disease and prior abnormal nuclear rest/stress single-photon emission CT (SPECT). The CT scan was acquired with retrospective ECG-gating and the following scan parameters: 330-ms gantry rotation, pitch 0.2, and 32×2×0.6-mm …

Conclusions. The facial nerve courses shown by preoperative CT imaging coincide with the surgical findings in most congenital aural atresia cases. CT scanning is critical in evaluation of a patient's candidacy for atresia surgery. Objectives. To evaluate the diagnostic value of preoperative CT scanning of the facial nerve course in congenital aural atresia. Subjects and methods. All inpatients (135 cases) with congenital aural atresia had routine preoperative CT examination. The facial nerve courses were observed in the operation and compared with the preoperative CT imaging. Results. CT imaging showed that the mastoid portions of the facial nerves in 57% of cases (77/135) were located at the level of the round window, and 17% (23/135) were located at the levels of the oval window and the cochlea. Differential overlapping of the oval window by the facial nerve could also be shown in most of the cases. In the majority of cases (75%, 61/81) the tympanic portions of the facial nerve on CT imaging could be confirmed by surgical findings. In severe overlapping of the oval window or cases with anterior displacement, stapedectomy or tympanoplasty, respectively, could not be performed as usual.

Differentiation of direct inguinal hernias, indirect inguinal hernias, and femoral hernias is often difficult at clinical examination and presents challenges even at diagnostic imaging. With the advent of higher-resolution multidetector computed tomography (CT), the minute anatomic detail of the inguinal region can be better delineated. The authors examine the appearance of these hernias at axial CT, as the axial plane remains the diagnostic mainstay of evaluation of acute abdomen. They review and label key anatomic structures, present cases of direct and indirect inguinal hernias and femoral hernias, and demonstrate their anatomic differences on axial images. Direct inguinal hernias protrude anteromedial and inferior to the course of the inferior epigastric vessels, whereas indirect inguinal hernias protrude posterolateral and superior to the course of those vessels. The proposed lateral crescent sign may be useful in diagnosis of early direct inguinal hernias, as it represents lateral compression and stretching of the inguinal canal fat and contents by the hernia sac. Femoral hernias protrude inferior to the course of the inferior epigastric vessels and medial to the common femoral vein, often have a narrow funnel-shaped neck, and may compress the femoral vein, causing engorgement of distal collateral veins. Familiarity with these anatomic differences at axial CT, along with the lateral crescent sign of direct inguinal hernias, may help the radiologist better assist the clinician in accurate diagnosis of the major types of hernias of the inguinal region. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.312105129/-/DC1.

Relationship of the optic nerve to the posterior paranasal sinuses: A CT anatomic study

Introduction. The region of the pterygo-mandibular space is an anatomical formation that is quite often sub- jected to surgical interventions (blockade of the mandibular nerve and its branches, operations for purulent processes, injuries). Among the complications of these surgical interventions, there are contractures of the lower jaw, neuritis of the lower alveolar and lingual nerves, and failure of anesthesia during blockades of these nerves. The purpose of the study was to analyze literature data and anatomical preparations of the pterygo-mandibular space, to take into account different options for the location of nerves and blood vessels during blockades and operations. Material and methods. The analysis of the literature and our own anatomical studies of 8 preparations of the deep parts of the human head was carried out. Results and discussion. The pterygo-mandibular space has a rather complex topographic and anatomical structure. Its anatomical structures are mobile along with the lower jaw and, accordingly, are adapted to these conditions in the form of a tortuous course of nerves and blood vessels, which prevents their stretching, tension, and injury. These features must be taken into account when performing surgical interventions, blockades of sensory and motor nerves in this area. Spatial perception of the location of the anatomical structures of the pterygo-mandibular space is facilitated by describing them relative to the lateral and medial muscles. Conclusions: The topographic and anatomical structure of the pterygo-mandibular space is variable and complex, which must be taken into account when performing nerve blocks, diagnostics, operations for purulent processes and traumatic injuries. The pterygo-mandibular space, connected directly with the peripharyngeal, should also be considered as part of the oral pharynx communicating with the base of the skull and neck.

Contrast CT imaging is a useful method to highlight structures such as blood vessels and tissue. The aim of this study was to generate contrast enhanced CT image for defining region of blood vessels and tumor from PET/CT image using deep learning approach. The deep learning approach in this study was based on conditional generative adversarial network (cGAN). The structure of cGAN composed of two convolutional neural network (CNN), generator and discriminator. Generator was trained to generate contrast CT (G-CCT) image from CT image which cannot be discriminated from the original contrast CT (CCT) image. Discriminator was trained to discriminate CCT image from G-CCT image by generator. To improve the generation performance of the model, we applied adaptive histogram equalization as image preprocessing. We compare the model trained with CT and the model with histogram equalized CT. Structural similarity index measurement (SSIM) was calculated to measure the similarity between G-CCT and CCT image. We defined and compared the region of lymphoma in left upper cervical lymph node level 2 using CT, CCT, and G-CCT. Detect the lymph node cancer was calculated by short to long axis ratio (S/L) method. In the case of the model trained with CT, SSIM was 0.9493±0.0183 in training phase and 0.9055±0.0484 in testing phase. In the case of the model trained with histogram equalized CT, SSIM was 0.954±0.0149 in training phase and 0.9081±0.047 in testing phase. G-CCT images showed more enhanced contrast in blood vessels and tumor region than CT image. Lymph node cancer S/L of CT, CCT, and G-CCT were 0.412, 0.395, and 0.397, respectively. The tumor S/L of generated contrast CT image was evaluated similar to these of real contrast CT image. This contrast CT image generation based on deep learning is helped for a cost-effective and less-hazardous process of acquiring contrast CT image to patients as well as more anatomical information with only CT scan.

The patient’s imaging features, especially the honeycomb pattern of ossific changes in the geniculate fossa, were virtually pathognomonic for ossifying hemangioma of the facial nerve.

Background: Branch retinal vein occlusion (BRVO) is the second-most common retinal vascular disorder. Arteriosclerotic changes at the site of obstruction and hemodynamic turbulence within the vessels are considered risk factors. Overcrossing of the vein by an artery has traditionally been considered to increase the risk of BRVO. Recent studies using optical coherence tomography and optical coherence tomography angiography have suggested a higher prevalence of vein-over-artery crossings in this disease. Nevertheless, uncertainty persists as to why some patients, even those with the same disease duration, have varying degrees of venous dilation and develop sufficient collaterals, while others develop substantial ischemia and its sequelae.&#x0D; Hypothesis: Herein, it is hypothesized that because retinal blood vessels are transparent, tubular, and collapsible conduits coursing over a hollow spherical surface, the changes related to AV crossings over the entire course of a vessel, rather than at any single isolated crossing, could contribute to the risk, natural progression, and outcomes of BRVO. The study analyzed color fundus photographs from two image datasets. The first dataset comprised 100 randomly selected images from the author’s own collection at the Rajendra Prasad Center for Ophthalmic Sciences. The second dataset comprised 100 images from the MESSIDOR database; three images were excluded owing to poor focus. Using 394 observations from 197 retinal photographs, four distinct patterns of AV crossing along the course of blood vessels were recognized: (A and B) wicker basket, (C) straight, (D) widely spaced, and (E) indeterminate. The percentages of tight wicker, loose wicker, straight, widely spaced, and indeterminate patterns in the two image sets were 19% (38/200) and 16.5% (32/194), 22.5% (45/200) and 27.8% (54/194), 16.5% (33/200) and 15.5% (30/194), 22.5% (45/200) and 28.4% (55/194), and 19.5% (39/200) and 11.9% (23/194), respectively. Hence, the wicker basket pattern was the most common AV crossing pattern in both image sets.&#x0D; Conclusions: The wicker basket pattern may provide structural stability and aid in maintaining pressure gradients within the retinal vascular bed. This observation of variable AV relationships at consecutive crossings may improve our understanding of the pathogenesis, natural history, and outcomes of BRVO. Future longitudinal studies including patients at risk of BRVO, or retrospective analyses of patients with BRVO who had ophthalmic examinations and archived fundus images before the vascular event, should verify the relevance of these observed vascular patterns.

BACKGROUND: In order to take advantage of the latest treatment options and keeping in mind that „time is brain` in stroke management , the goal of imaging is to diagnose as early as possible, obtain accurate information about the cerebrovascular system and brain tissue perfusion, select the correct therapy and improve the outcome of one of the most debilitating and costly to society diseases. LEARNING POINTS: to describe the basics of CT and MR techniques used to evaluate stroke; to determine an imaging protocol for acute stroke evaluation; to recognize the significance of a penumbra for therapy and prognosis after acute stroke. MAIN BODY: Overall evaluation can be performed with computed tomography (CT) and/ or magnetic resonance (MR) . Native CT can be performed rapidly to identify the early signs of ischemia and to exclude haemorrhage. CT angiography and CT perfusion, may display intravascular thrombosis and the penumbra . These tests are easy to perform on most spiral CT devices and are increasingly used in patients with IMI to decide on the type and volume of the necessary intervention. Although acute attacks can be seen at the start of the conventional MR I , diffusion is the most sensitive series for the detection of hyper acute ischemia. Gradient-echo MR sequences can be useful for detecting bleeding; t he neck and intracranial vessels can be assessed with MR angiography, and the presence of „mismatch` between the diffusion and perfusion can predict the existence of the penumbra. CONCLUSION: Imaging technology has advanced rapidly in the past two decades, and current imaging techniques can be used to identify hyperacute stroke and guide therapy by providing information about the functional status of ischemic brain tissue. Both CT and MR imaging are useful for the comprehensive evaluation of acute stroke and can provide important and necessary information for therapy planning.

Anatomical variations within the deep posterior compartment of the leg and important clinical consequences

C.A.T. of the Head.- Anatomy.- Computerised Axial Tomography and the Normal Brain.- C.A.T. Scanning: Correlations with Vascular and Topographical Anatomy.- C.A.T. Investigation of the Subarachnoid Space.- Computerised Tomography of the Tentorium Cerebelli.- Technical Operation.- Computer Tomographic Artefacts Using the CT 1000.- C.A.T. Under Stereotaxic Conditions.- Application of Receiver Operating Characteristic Curve Data in the Evaluation of Hard Copy and an Interactive Display from an EMI Scanner.- Costing and Logistics.- Departmental Logistics: C.A.T. in a Neurological Hospital.- Logistics: A Neuroradiological Service. Cost-Effectiveness of an EMI Brain Scanner.- C.A.T. of Brain and Body in a General Hospital.- Head Injuries.- Role of C.A.T. in the Diagnosis and Management of Traumatic Intracranial Haematoma.- C.A.T. and Angiography in Cranial Trauma.- Tumours Above and Below the Tentorium.- Radiological Management of Tumours.- Computerised Axial Tomography in Supratentorial Gliomas and Metastases.- Intracranial Epidermoid and Dermoid Tumours.- Meningiomas Diagnosed by Scanning: A Review of 100 Intracranial Cases.- A German Multicentre Study of Intracranial Tumours.- C.A.T. Investigations of the Development of Oedema and the Effects of its Treatment in Patients with Brain Tumours.- A Diagnostic Approach to Cerebellar Lesions.- C.A.T. Scanning in Tumours of the Cerebellopontine Angle.- C.A.T. Studies of Tumours of the Skull Base and Face.- Tumours and Other Lesions of the Visual Pathways.- Comparative Values of Various Neuroradiological Investigations in the Diagnosis of Intracranial Optic Pathway Lesions.- An Evaluation of C.A.T. in the Diagnosis of Orbital Space-Occupying Lesions.- C.A.T. Scanning in Diseases of Children.- Computerised Axial Tomography and Paediatric Neurosurgery.- C.A.T. in the Diagnosis and Management of Childhood Hydrocephalus.- C.A.T. in the Phakomatoses.- Diseases of the Brain Parenchyma, and Hydrocephalus.- Role of C.A.T. in the Diagnosis and Management of Intracranial Infections.- C.A.T. in Leukodystrophy and Neuronal Degeneration.- C.A.T. in Multiple Sclerosis.- Hydrocephalus, and Their Differential Diagnosis - CSF Dynamics Investigated by Computer Cisternography.- Clinical Significance of Cerebral Atrophy as Shown by C.A.T..- Computerised Axial Tomography and Dementia in the Elderly.- Vascular Conditions.- Use of C.A.T. in Infarction.- C.A.T. Studies of Ischaemia.- Jacksonian Epileptic Seizures as Inaugural Manifestations of Sylvian Infarctions Revealed by Computerised Axial Tomography (C.A.T.).- Vascular Disease of the Visual Radiation and Cortex.- Cerebral, Cerebellar and Pontine Haemorrhages.- Diagnosis of Subarachnoid Haemorrhage by Computerised Tomography in Intracranial Aneurysms.- Use of Computerised Axial Tomography (C.A.T.) for the Diagnosis and Management of Intracranial Angiomas.- Study of Blood Volume by C.A.T. and a Comparison with Other Methods.- Measurements: Physical Considerations.- Electron Density and Atomic Number Determination - Methods, Limitations and a Study of Colloid Cysts.- Bone Mineral Estimation Employing Computer Assisted Transverse Axial Tomography - A Preliminary Study.- Physical Performance of a Prototype CT5000 EMI Body Scanner.- Body Scanner in Neurological Disease.- Total Body Scanner in Neurological Disease.- Computer Tomography of the Spine - A Preliminary Report.- C.A.T. of the Body.- Anatomy.- Some Anatomical Problems of Computerised Axial Tomography.- Computerised Tomography of Abdominal Blood Vessels.- C.A.T. in the Pelvis.- C.A.T. of the Soft Tissues.- Liver Pancreas.- Imaging the Liver and Pancreas - A Clinician's View.- C.A.T. of the Pancreas.- C.A.T. in Acute and Chronic Pancreatitis.- Oncology.- Whole Body C.A.T. Scanner and the Oncologist.- C.A.T. of the Lymphomas.- C.A.T. Scanning in Lymph Node Disease.- Evaluation of Normal and Abnormal Lymph Nodes at Computerised Tomographic Scanning of the Abdomen and Pelvis.- The Manchester Experience.- Computed Tomography of the Breast. A Report of a Pilot Study.

To determine the effects of arm position on the appearance of structures in the upper chest as seen on computed tomography (CT), such as clavicular angle, course of axillary vessels, pectoralis major muscle, and bicipital groove. The study consisted of 52 chest CT examinations (32 from men and 20 from women; mean [SD] age, 64 [20] years) performed with 1 or both arms at or above the shoulder (n = 44 arms) or by the side of the body (n = 60 arms). Three chest radiologists assessed randomized CT examinations for specific anatomical structures including orientation of the bicipital groove of the humerus, appearance of the pectoralis major muscle, and the course of the axillary vessels. Orientation of the clavicle and the scapula were assessed by measuring their angles with the mid-sagittal plane. Data were analyzed using the Student t test. There was a significant difference in the mean angle of the clavicles with the mid-sagittal plane in arms at or above the shoulder level (41.3 +/- 11.7 degrees) compared with arms-by-side position (54.8 +/- 14.7 degrees; P < 0.0001), but no significant difference was found in scapular angles (P = 0.4). All 3 radiologists found anteriorly directed bicipital groove, flat pectoralis major, and straight course of the axillary vessels from the chest to the axilla when arms were by the side. With arms at or above the level of the shoulder, however, the bicipital groove was directed posteromedially, the pectoralis major was buckled, and the axillary vessels had an angulated course. The bicipital groove, the pectoralis muscles, the axillary vessels, or the angle of the clavicle with the mid-sagittal plane on transverse CT images can help predict the position of the arms in patients undergoing chest CT.