Examination 6
case 01
(a) Posterior sub-talar joint (PSTJ). The PSTJ is a synovial joint formed by the articulation
of the posterior articular facets of the talus and calcaneum. Intra-articular
extension into the PSTJ is often seen in comminuted calcaneal compression fractures
and represents an important factor in the surgical classification of these injuries.
(b) Cuboid. The cuboid possesses a proximal articular surface that only articulates
with the calcaneum. Distally the cuboid articulates with the fourth and fifth
metatarsals.
(c) Neck of the talus. The talar neck is an important review area when evaluating
ankle radiographs and CT in the setting of trauma. Missed talar neck fractures can
result in avascular necrosis of the talar dome due to its blood supply being derived
from vessels that enter the talar head and travel proximally within the neck.
(d) The sinus tarsi. This is a fatty space beneath the talar neck and above the calcaneal
body. The sinus tarsi also contains the cervical and interosseous ligaments along with
traversing nerves and vessels. Inflammation and cyst formation in this space
following trauma may produce a painful ‘sinus-tarsi syndrome’.
(e) Os trigonum. This is present in 10% of individuals and when present, is bilateral in
50%. It may be present as a separate ossicle or be partly fused with the posterior talar
process forming a synchrondrosis. The os trigonum may produce repetitive soft tissue
impingment in the ankle due to repetitive plantar-flexion resulting in a painful
‘os-trigonum syndrome’.
case 02
and upper abdomen
(a) Rectus abdominus muscle.
(b) Left lobe of liver.
(c) Portal vein.
(d) Aorta.
(e) Pylorus.
In infants pyloric stenosis is diagnosed if the single wall thickness of the pylorus is
greater than 6 mm and the pyloric length is greater than 17 mm.
The stomach will often be distended with feed despite projectile-type vomiting.
The pylorus is not seen open and there is no passage of stomach contents into the
duodenum during scanning. Typically presentation is at about 6 weeks of life.
case 03
(a) Right subclavian artery. This arises from the bifurcation of the brachiocephalic
trunk behind the right sternoclavicular joint. An anomalous right subclavian artery
occurs in 1% of the population.
(b) The brachiocephalic trunk. This bifurcates into the right common carotid and
subclavian arteries and is the first major branch of the ascending aorta.
(c) Left common carotid artery. In 20% of the population this takes origin from the
brachiocephalic trunk.
(d) Left vertebral artery. This travels through the transverse foramina of C6 to C1
where it passes medially to enter the foramen magnum.
(e) Left internal carotid artery. This begins at the level of C4 at the carotid bifurcation.
Imaging of the carotid arteries and other vessels with MR can largely be achieved
without contrast. Either the signal from flowing blood entering an image plane can be
measured (time of flight MRA) or the velocity differences in flowing blood can
measured (phase contrast MRA). However, these imaging techniques depend on
laminar flow and therefore turbulent flow, as seen with stenoses, can result in signal
loss and subsequent overestimation of stenoses and occlusion.
case 04
MRCP of a post-cholecystectomy patient. Heavily T2-weighted maximum intensity
projection (MIP) image of the biliary tree.
(a) Right anterior hepatic duct.
(b) Right posterior hepatic duct.
(c) Left hepatic duct.
(d) Common bile duct.
(e) Pancreatic duct.
Classical biliary tree anatomy occurs in about 58% of the population. The normal
anatomy is the right hepatic duct and left hepatic duct draining the right and left lobes
of the liver. The right hepatic duct branches into posterior duct draining segments VI
and VII. The right posterior duct runs horizontally and posterior to the anterior duct
and fuses to form the right hepatic duct. The anterior duct drains segments V and VIII.
The left duct drains II–IV.
The commonest variant, in 15.6% of the population, is the right posterior duct
draining into the left hepatic duct. The right anterior and posterior ducts fuse with
the left to form a trifurcation in some people.
case 05
(a) Radial styloid process. This forms the dorsal and radial margins of the radiocarpal
joint and may become fractured during forced radial and dorsal deviation of
the wrist due to impaction by the scaphoid. This fracture was traditionally termed the
‘chauffeur's fracture’ due to the mechanism of injury sustained by turning a stiff
crankshaft on old cars.
(b) Distal radio-ulnar joint (DRUJ). The DRUJ is a synovial joint formed by the
sigmoid notch of the radius and the convex articular surface of the ulna. It is
important as it facilitates wrist supination and pronation whilst the elbow is fixed.
The distal margin of the joint is covered by the triangular fibrocartilage (TFC) and its
supporting ligaments, thus TFC injury can lead to DRUJ instability.
(c) Ulnar styloid. The ulnar styloid projects distally from the dorsal aspect of the
distal ulnar. It bears attachment of many important structures including the supporting
ligaments of the TFC and the sheath of the extensor carpi ulnaris tendon.
It is commonly avulsed during wrist trauma by traction of these structures, which
frequently results in fracture non-union.
(d) Trapezium. This forms a synovial saddle joint with the base of the metacarpal
of the thumb. This joint is a common site for primary osteoarthritis due to its
frequent use.
(e) Flexor pollicis longus (FPL). The paired FPL sesamoids are present in nearly all
individuals and lie either side of the FPL tendon beneath the metacarpo-phalangeal
(MCP) joint of the thumb. They are analogous to the paired flexor halluces longus
(FHL) sesamoid bones found beneath the metatarso-phalangeal (MTP) joint of the
hallux.
case 06
(a) Rugal folds of the stomach. When contracted the gastric mucosa is thrown into
longitudinal ridges. They are most marked in the pyloric region and along the lesser
curve.
(b) Transverse colon. Contains solid faecal matter and therefore on this T2-weighted
fast field echo image appears of low signal mixed with air.
(c) Gallbladder. The bile shows as high signal on this T2-weighted image.
(d) Caecum. It appears high signal as there is still a certain amount of fluid within the
faeces at this stage.
(e) Ileum. Note the wall is smooth and shows no obvious thickening or change in the
surrounding tissue.
case 07
(a) Optic chiasm.
(b) Right middle temporal gyrus.
(c) Left lateral ventricle.
(d) Pituitary stalk.
(e) Right internal carotid artery in cavernous sinus. The cavernous sinus is a large
thin-walled vein bordered by the temporal and sphenoid bones and lying lateral to
the sella turcica. In addition to the internal carotid artery, the III, IV, V and VI cranial
nerves also lie within the sinus.
Coronal MRI is useful for assessing the pituitary gland. When learning, a lot of
radiologists think the sagittal sequence is more useful, but in practice the coronal
sequence enables complete assessment of the pituitary when pre- and post-contrast
T1-weighted sequences are obtained. The superior surface of the pituitary is concave
or horizontal upwards. Any convexity upwards suggests a space-occupying lesion.
The pituitary stalk should lie in a central position and the pituitary gland should
enhance uniformly. An area of pituitary that does not enhance may be caused by a
pituitary microadenoma.
case 08
(a) Urinary bladder.
(b) Rectus abdominis muscle.
(c) Prostate.
(d) Coccyx.
(e) L4/L5 intervertebral disc.
Thin sections are taken in all three planes when evaluating the prostate in order to
ascertain if there is any extra-capsular disease.
MRI bladder includes dynamic, contrast-enhanced images as bladder tumours are
hypervascular and show early enhancement. This ensures that correct staging can be
performed. Sequences performed also include images of the upper tracts to ascertain
if there is any hydronephrosis, hydroureter or ureteric tumour. CTU will often be performed in conjunction with MRI as transitional cell tumours can occur separately,
both in the bladder and the upper tracts.
It is important to look at the entire image, even though it may be centred on a
specific organ. Although T1-weighted images are optimum for evaluating bone
marrow, look at the vertebral alignment on any sagittal images and for any intervertebral
disc disease.
case 09
projection) image
(a) Right internal carotid artery.
(b) Right internal thoracic artery.
(c) Right superior thyroid artery.
(d) Right common carotid artery (CCA).
(e) Right subclavian artery (SCA). It is difficult to ascertain this is the right side on this
image. However, the anatomical relationship of the right SCA with the common
carotid artery (CCA) is the clue.
case 10
(a) Epididymal head.
(b) Testis.
(c) Epididymal tail.
(d) Mediastinum testis.
(e) Tunica albuginea.
case 11
This image is a single frame from a 4-chamber cardiac MR white blood cine (steady
state free precession) examination.
(a) Left atrium.
(b) Inter-atrial septum.
(c) Mitral valve.
(d) Papillary muscle.
(e) Moderator band. The right ventricle (RV) is more heavily trabeculated than the
left and also has a thick muscular band running across the distal RV cavity from the
septum to the base of the anterior papillary muscle. This is called the moderator band
and carries the right bundle branch of the atrio-ventricular (AV) conduction system to
the anterior papillary muscle. The moderator band is only seen in the RV and its
presence is used to identify the RV on fetal echocardiogram.
case 12
(a) Superior mesenteric artery (SMA). This artery arises from the aorta at the level of
the L1 vertebra. The inferior mesenteric artery arises from the anterior or left anterolateral
aspect of the aorta at L3 vertebral level.
(b) Jejunal branch of the SMA. There are usually between four and six jejunal
branches.
(c) Ileal branch of the SMA. There are usually between 9 and 13 ileal branches which
arise after the ileocolic artery.
(d) Right colic artery.
(e) Replaced right hepatic artery. The right hepatic has an aberrant origin from the
SMA rather than from the common hepatic artery. (It is faintly visible rising diagonally
to the right from close to the catheter tip.)
case 13
(a) Left internal thoracic (mammary) artery.
(b) Left brachiocephalic vein.
(c) Superior vena cava.
(d) Brachiocephalic (innominate) trunk (artery).
(e) Left trapezius muscle.
case 14
(a) Left lobe of the liver.
(b) Common hepatic artery. In normal subjects this may be difficult to see on colour
Doppler because of its small diameter and tortuous course.
(c) Splenic artery. This is the largest branch of the coeliac trunk that follows a tortuous
course posterior to omental bursa along the superior border of the pancreas.
(d) Aorta.
(e) Vertebral body. Typically the coeliac axis arises at the T12/L1 level.
case 15
(a) Subglottis. This is the area immediately below the cords and is an important area
for assessing tumour spread in laryngeal carcinoma.
(b) Right vocal cord. The vocal cords are identified by their muscle signal intensity.
(c) Left submandibular gland. The normal gland appears of intermediate signal
intensity compared with muscle on both T1-weighted and T2-weighted images.
(d) Midline septum of the tongue. This is high signal on T1-weighted and
T2-weighted images due to fat content.
This is an important landmark when staging tongue tumours to assess spread
across the midline.
(e) Soft palate. This marks the division between the naso- and oropharynx.
case 16
(a) Right oblique (major) fissure.
(b) Right pectoralis minor muscle.
(c) Right subclavian vein. This is dense on this image as it contains the intravenously
administered contrast.
(d) Right subclavian artery.
(e) Horizontal (minor) fissure. The horizontal fissure bulges so that there is a convex
upper border.
The horizontal fissure is higher medially than laterally and higher posteriorly than
anteriorly. It is only present in the right lung since the left lung lacks a middle lobe.
It normally extends from the oblique fissure at the level of the fourth rib.
case 17
(a) Gas in vocal cord.
(b) Base of tongue.
(c) Hyoid bone.
(d) Styloid process.
(e) Anterior tubercle of transverse process of C5.
case 18
(a) Trapezium.
(b) Lunate.
(c) Pisiform.
(d) Scaphoid.
(e) Ulnar styloid.
case 19
(a) Pubic bone.
(b) Bladder.
(c) Endometrium.
(d) Rectus abdominus muscle.
(e) Junctional zone between myometrium and endometrium.
On T2-weighted images the endometrium is of high signal. The junctional zone is of
low signal and the myometrium of intermediate signal.
case 20
(a) Duodenum – third part.
(b) Left anterior renal fascia.
(c) Left lateral conal fascia.
(d) Right posterior renal fascia.
(e) Retro-aortic left renal vein. A retro-aortic left renal vein is seen in about 2% of the
population. In some situations the vein is posterior to the artery at the renal hilum.
The anomalous vein may receive tributaries from the lumbar veins and can be
associated with a higher incidence of left-sided varicoceles in males.
A circumaortic left renal vein occurs in about 8% of cases. There are two left renal
veins – the superior component receives blood from the left adrenal vein and is
anterior to the aorta. The inferior component is posterior to the aorta and receives
blood from the gonadal vein. It is important in pre-operative planning of nephrectomy
and in misdiagnosing lymphadenopathy.
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