See Right Through Me

The central nervous system (CNS) comprises the brain and the spinal cord and includes the supplying vessels, meningeal coverings, and cerebrospinal fluid (CSF). Any single cross-sectional image contains all of these. It is useful to appreciate each of these components for a fixed number of cross-sectional positions. Each of these positions should be named according to some characteristic finding on that slice. More detailed anatomy is required for the midline sagittal cut. The suprasellar region, the pineal region, the posterior fossa, and the region of the major deep grey nuclei have many detailed anatomical labels and have been highlighted individually. This chapter provides a tour in the axial, coronal, and sagittal planes, and then draws attention to details of specific regions. There are also special sections on the hippocampus, cerebral vessels, cranial nerves, and spinal cord. Surface anatomy, functional areas, and white matter tracts are presented in detail as they represent emerging tools representing anatomy not well-visualised using traditional methods. The globe and pituitary gland will be dealt with in more detail in other sections of this book.

Association pathways are intrahemispheric tracts joining different cortical areas in the same hemisphere. Short fibres make up the subcortical U-fibres. Long tracts are located in the deep white matter.

This chapter will illustrate the imaging of the 12 cranial nerves (CNs). The pathway of each nerve will be demonstrated by the modality best suited to each portion. Where the nerve itself may not actually be seen, a landmark structure is indicated in its path instead.

The various levels are demonstrated using multiplanar magnetic resonance imaging (MRI).

The paranasal sinuses are air cavities situated within the cranial and facial bones. The apertures of these cavities communicate with the nasal cavity. There are four paired paranasal sinuses:

This complicated area is best imaged with MRI in the coronal plane. The brachial plexus is found by using the subclavian artery as a landmark on the coronal images.

The best ways to evaluate the ear are (1) high-resolution CT scanning on bone algorithm and window in the axial and coronal planes to demonstrate bony detail, and (2) high-resolution T2-weighted MRI in the axial and coronal planes to demonstrate fluid-filled components.

When imaging the soft tissues of the neck, plain radiography is of limited value compared to the newer modalities. Sialography is a useful diagnostic tool for assessment of the anatomy of the salivary ducts. Soft tissue views of the larynx are sometimes used to search for radio-opaque foreign bodies and for evaluation of laryngeal cartilaginous structures.

The pituitary gland is composed of three lobes

Plain film: chest radiograph (CXR).

The standard chest radiograph views are the posteroanterior and lateral projections. The other radiographic views are requested less frequently as cross-sectional imaging becomes more available.

The biliary and pancreatic duct systems are imaged by radiologists and surgeons with or without interventional techniques and with or without introduction of contrast. Contrast is introduced via an endoscope in a retrograde manner, percutaneously, via an indwelling “T-tube”/cholecystostomy tube, intravenously and even orally. The systems may also be demonstrated free of vascular flow on ultrasound and free of contrast enhancement on CT and MRI. This chapter will demonstrate the anatomy of these systems in multiple views and planes using the available imaging techniques.

The pancreas and spleen are well imaged using ultrasound, CT scan and MRI. CT scan is the modality of choice when visualization on ultrasound is suboptimal and where it is available. MRI is fast gaining popularity in imaging both the spleen and pancreas.

Plain films obtained in the supine position demonstrate the bowel gas pattern.

Both female and male genital tracts are adequately demonstrated using ultrasound techniques either transabdominally, via the vagina/rectum, or directly as is the case of the testes. Additional information is provided by MRI, which demonstrates the anatomy in more detail. Specific contrast investigations such as the hysterosalpingogram are still in use as is the cavernosogram. Vascular anatomy is demonstrated with ultrasound, angiography, and multidetector CT. The genital system is also imaged incidentally during CT examinations but CT is not primarily used for this purpose.

Periarticular structures and bone or marrow pathology can be well visualised with uncontrasted MRI. Intra-articular pathology, particularly lateral injury, is only assessed accurately with direct MR arthrography.

Greater part of the pelvis formed by two innominate bones each made up of ilium, ischium and pubis.

The vertebral column is composed of cervical, thoracic and lumbo-sacral components. The atlas (CI), axis (C2) and sacrum have specific appearances but other vertebrae have features common to them. Evaluation should include the components of the vertebrae (body, end-plates, pedicles, laminae, spinous processes and marrow), the inter-vertebral disc components (nucleas pulposus and annulus fibrosus) and facet joint components, as well as the ligaments and muscles. This chapter does not include the contents of the spinal canal and neural foramina, which are dealt with in the chapter on the Spinal Cord. Plain radiographs and CT are best suited to evaluating the bony components while MRI is best suited to demonstrating the inter-vertebral discs, ligaments, muscles and marrow.

The purpose of the chapter is for the reader to be able to identify and name vessels when reporting vascular studies.

On a well-inspired CXR the trachea will be straight or show a gentle curve away from the aortic arch (usually towards the right).

The axis has multiple ossification centers. The summit or tip of the dens ossification centre appears between 2 and 6 years and fuses with the main odontoid mass between 11 and 12 years. The synchondrosis between the dens and body disappears between 3 and 7 years.