12 sample questions from the 2186 Diagnostic Radiology Paper 2 questions in FCPS-1 Prep. Choose an answer to see why it is right and why each other option is wrong.
A coronal CT through the body of the sphenoid shows two openings on each side: the foramen rotundum superolaterally and a smaller canal inferomedially that runs back towards the foramen lacerum. Which structure passes through the inferomedial canal?
Answer: Nerve of the pterygoid canal
The inferomedial canal is the pterygoid (Vidian) canal, at the root of the medial pterygoid plate. It carries the nerve of the pterygoid canal, formed from the greater petrosal (parasympathetic) and deep petrosal (sympathetic) nerves, to the pterygopalatine ganglion. The foramen rotundum, superolateral to it, carries the maxillary nerve. On coronal CT the two canals are seen as paired openings, rotundum above and lateral, Vidian below and medial.
Pterygoid (Vidian) canal
Coronal CT: rotundum superolateral
Vidian canal inferomedial
Carries greater + deep petrosal nerves
Ends in the pterygopalatine fossa
Remember Rotundum high and lateral; Vidian low and medial.
Exam trap Both canals open into the pterygopalatine fossa, so position, not destination, tells them apart.
Why the other options are wrong
Maxillary division of trigeminal Passes through the foramen rotundum, the superolateral opening.
Greater palatine nerve and artery Runs in the greater palatine canal from the fossa down to the palate.
Mandibular division of trigeminal Leaves the skull through the foramen ovale.
Deep temporal nerve branches A branch of V3 in the infratemporal fossa, not in a sphenoid canal.
Question 2Medium
A 12-year-old girl treated for a suprasellar tumour invading the floor of the third ventricle has since had an insatiable appetite and has gained 20 kg in a year. Damage to which hypothalamic nucleus best explains this?
Answer: Ventromedial nucleus
The ventromedial nucleus acts as a satiety centre, responding to leptin and insulin signals from fat stores to inhibit feeding. Destruction of this region removes satiety, causing hyperphagia and severe obesity, a well-known problem after craniopharyngioma or its surgery. The lateral hypothalamic area acts as a feeding centre, and its destruction causes loss of appetite and weight loss. The supraoptic nucleus makes vasopressin, and the suprachiasmatic nucleus sets circadian rhythm.
Exam trap Diet alone rarely controls hypothalamic obesity because satiety signals are lost.
Why the other options are wrong
Lateral hypothalamic area Its loss causes anorexia and weight loss.
Supraoptic nucleus Its loss causes diabetes insipidus.
Suprachiasmatic nucleus Its loss disturbs sleep-wake rhythm.
Posterior hypothalamic nucleus Its loss impairs heat conservation, causing poikilothermia.
Question 3Easy
A radiographer is checking whether a PA chest film was taken in adequate inspiration. In the midclavicular line, which anterior rib should the dome of the right hemidiaphragm meet in a good inspiratory film?
Answer: 6th anterior rib
A film is taken in adequate inspiration when about six anterior ribs, or nine to ten posterior ribs, are seen above the right hemidiaphragm in the midclavicular line. Poor inspiration crowds the lung bases and broadens the heart, mimicking cardiomegaly and basal shadowing. More than six to seven anterior ribs with flat diaphragms suggests hyperinflation.
Inspiration on CXR
About 6 anterior ribs above the dome
Or 9 to 10 posterior ribs
Poor effort: heart looks large
Over 7 with flat domes: hyperinflation
Remember Count six anterior ribs to the right dome.
Exam trap A poor inspiratory film can make a normal heart look enlarged.
Why the other options are wrong
3rd anterior rib Far too high; this would be a very poor inspiration.
4th anterior rib Still too high for a good inspiration.
9th anterior rib Too low; this suggests hyperinflation.
11th anterior rib The 11th rib does not reach the anterior chest.
Question 4Medium
Five days after an uncomplicated open cholecystectomy, a slim 30-year-old woman has an erect chest film for a cough. A thin crescent of gas is seen under the right hemidiaphragm. She is eating, afebrile and her abdomen is soft. What is the most likely explanation?
Answer: Residual gas from the operation
Air enters the peritoneal cavity at every laparotomy and is gradually absorbed. A small amount of free gas is commonly seen for several days after surgery, sometimes longer in slim patients, and in a well patient with a soft abdomen it is expected. Free gas that increases on serial films, or that appears with sepsis or peritonism, suggests a leak or perforation. A bile leak gives fluid and pain rather than gas, and an abscess shows a fluid level in an unwell patient.
Postoperative free gas
Normal after laparotomy
May persist several days
Longer in slim patients
Worry if it increases or patient unwell
Remember A little free gas after surgery in a well patient is expected.
Exam trap Comparing with earlier films is more useful than a single film; rising gas suggests a leak.
Why the other options are wrong
Leak from the cystic duct stump A bile leak produces fluid and pain, not isolated gas.
Perforated duodenal ulcer She is well with a soft abdomen.
Subphrenic abscess Shows a fluid level with fever.
Colonic interposition Shows haustra and stays fixed; not linked to recent surgery.
A construction worker falls 6 metres and lands on his right leg. His right leg is shortened, and the whole right hemipelvis has been driven upwards, with fractures of both right pubic rami, disruption of the right sacroiliac joint and avulsion of the tip of the L5 transverse process. What is this pattern of injury?
Answer: Vertical shear injury
A vertical force through one leg drives the hemipelvis upwards. The anterior ring breaks through the pubic rami or symphysis, and the posterior ring fails through the sacroiliac joint or sacrum, with tearing of all the posterior ligaments. Avulsion of the L5 transverse process, where the iliolumbar ligament attaches, is a sign of this posterior disruption. The hemipelvis is unstable both rotationally and vertically, and bleeding from torn pelvic vessels is common.
Exam trap An L5 transverse process fracture on a pelvic film should prompt a search for posterior ring injury.
Why the other options are wrong
Lateral compression injury A side impact that rotates the hemipelvis inwards, without vertical displacement.
Open-book compression injury Widening of the symphysis without vertical shift of the hemipelvis.
Isolated acetabular fracture Does not displace the whole hemipelvis upwards.
Iliac wing fracture A stable fracture that leaves the pelvic ring intact.
Question 6Medium
Which artery mainly forms the superficial palmar arch, which crosses the palm at the level of the distal border of the fully extended thumb?
Answer: Ulnar artery
The superficial palmar arch is the more distal arch and lies at the level of the distal border of the fully extended thumb. It is formed mainly by the ulnar artery and completed by the superficial palmar branch of the radial artery. The deep palmar arch lies more proximally, at the level of the metacarpal bases, and is formed mainly by the radial artery. In many people the superficial arch is incomplete, which matters in assessing collateral flow.
Palmar arches
Superficial arch: ulnar artery mainly
Lies more distally (thumb's edge)
Deep arch: radial artery mainly
Deep arch at metacarpal bases
Remember Ulnar is superficial and distal; radial is deep and proximal.
Exam trap The superficial arch is often incomplete, so collateral flow should be checked before radial artery harvesting.
Why the other options are wrong
Radial artery Mainly forms the deep palmar arch, more proximally.
Anterior interosseous artery Ends in the forearm; it does not form a palmar arch.
Princeps pollicis artery A branch of the radial artery to the thumb, not an arch.
Common interosseous artery Divides into the interosseous arteries in the forearm.
Question 7Easy
Twenty minutes after a successful lumbar sympathetic block, the patient's foot on that side is warm, pink and dry. What explains the change?
Answer: Loss of α1-mediated constriction of skin vessels
Blood vessels in the skin of the limbs have a sympathetic supply but almost no parasympathetic supply. Resting sympathetic tone keeps skin arterioles partly constricted through α1 adrenoceptors. Blocking the lumbar chain removes this tone, so skin vessels dilate and the foot becomes warm and pink. Sweating is lost too, because sweat glands receive only sympathetic (cholinergic) fibres, so the skin is dry.
Sympathetic tone in skin
Skin arterioles: α1 constriction
Block removes tone
Foot becomes warm, pink
Sweating lost: dry skin
Remember Warm, dry foot means the sympathetic block has worked.
Exam trap Diseased, fixed arteries may not dilate, so a warm foot does not guarantee better ischaemic healing.
Why the other options are wrong
Release of β2-mediated vasodilator tone Skin vessels are constricted by sympathetic tone; they do not depend on β2 dilator tone.
Increased parasympathetic supply to the foot Limb vessels have no meaningful parasympathetic supply.
Local anaesthetic acting on muscle arteries The drug is placed at the chain, not on the foot arteries.
Blocked sensory nerves releasing histamine Sensory block does not cause histamine release or warmth.
Question 8Medium
A 74-year-old man faints twice while shaving. Light pressure on the right side of his neck at the level of the upper border of the thyroid cartilage reproduces a 4-second pause on the monitor. Where are the receptors that drive this reflex?
Answer: Dilated origin of the internal carotid artery
Carotid sinus hypersensitivity causes syncope when the neck is pressed or turned. The carotid sinus is the dilated first part of the internal carotid artery, and its wall contains stretch receptors. Pressure on it mimics a rise in blood pressure, so the reflex slows the heart through the vagus and dilates vessels. The nearby carotid body is a chemoreceptor that senses low oxygen, not stretch.
Carotid sinus hypersensitivity
Sinus: dilated ICA origin
Stretch baroreceptors
Afferent IX, efferent X
Neck pressure: pause and syncope
Remember Sinus senses stretch; body senses oxygen.
Exam trap The carotid sinus and carotid body are both near the bifurcation but sense different stimuli.
Why the other options are wrong
Carotid body at the bifurcation A chemoreceptor responding to low PO2, not to stretch.
Wall of the aortic arch Aortic baroreceptors cannot be pressed through the neck.
Origin of the external carotid artery The external carotid has no sinus.
Mid portion of the common carotid artery The sinus lies at the start of the internal carotid, above this level.
Question 9Medium
A 35-year-old man has hypertension, haematuria and bilateral ballotable flank masses. His mother had cystic kidneys and died of a sudden severe headache at 45. Which intracranial lesion is he at increased risk of?
Answer: Intracranial berry aneurysm
Autosomal dominant polycystic kidney disease is caused by mutations in PKD1 or PKD2, which encode polycystins found in renal tubules and vessel walls. About 8–10% of patients have saccular (berry) aneurysms of the circle of Willis, and the risk is higher when a relative has had subarachnoid haemorrhage. A sudden severe headache followed by death suggests his mother had a ruptured aneurysm. Liver cysts and mitral valve prolapse are other extrarenal features.
ADPKD beyond the kidney
PKD1 or PKD2, autosomal dominant
Liver cysts common
Berry aneurysm risk
Screening if a relative had SAH
Remember Cystic kidneys plus family SAH: think berry aneurysm.
Exam trap Liver cysts in ADPKD rarely affect liver function, unlike the kidneys.
Why the other options are wrong
Cerebellar haemangioblastoma Seen in von Hippel-Lindau disease.
Cavernous malformation Not a feature of polycystic kidney disease.
Dural arteriovenous fistula Acquired lesion, not linked to ADPKD.
Moyamoya vessels Not associated with ADPKD.
Question 10Hard
A 34-year-old woman, three weeks after delivery, has an anterior STEMI. Her coronary arteries have no atheroma, but the mid LAD is narrowed by blood within its wall that compresses the lumen. What is the most likely cause?
Answer: Spontaneous coronary artery dissection
Spontaneous coronary artery dissection is a leading cause of myocardial infarction in young women, particularly around pregnancy and in fibromuscular dysplasia. Bleeding from the vasa vasorum or an intimal tear forms an intramural haematoma that compresses the true lumen, giving a long smooth narrowing on angiography rather than an irregular plaque. Hormonal changes in pregnancy are thought to weaken the arterial wall. Vasospasm relieves with nitrates and shows no wall haematoma.
Spontaneous coronary dissection
Young woman, often peripartum
Long smooth tapering narrowing
Intramural haematoma compresses lumen
Linked to fibromuscular dysplasia
Remember MI in a new mother with clean arteries: think dissection.
Exam trap Stenting a dissected artery can extend the haematoma; many heal without it.
Why the other options are wrong
Rupture of a lipid-rich atheroma plaque Unusual at this age without risk factors, and atheroma would be seen elsewhere.
Coronary vasospasm from ergometrine Ergometrine spasm reverses with nitrates and shows no intramural blood.
Paradoxical embolism through a PFO Gives an abrupt cut-off, not a long haematoma in the wall.
Kawasaki disease coronary aneurysm Causes aneurysms in children, not a smooth narrowing after pregnancy.
Question 11Medium
A 58-year-old man with long-standing ankylosing spondylitis slips and bumps his head. He has neck pain but walks in, and is found to have a transverse fracture passing through the C6–C7 disc and all the posterior elements of the fused spine. Why is this injury so dangerous after such minor trauma?
Answer: A rigid, brittle spine acts as a long lever
In advanced ankylosing spondylitis, syndesmophytes and fused facets turn the spine into a single rigid column, while the bone itself becomes osteoporotic. Even minor trauma concentrates force at one level, and the long fused segments above and below act as lever arms. Fractures therefore often pass transversely through all three columns, commonly through a disc space at the cervicothoracic junction, and are highly unstable. Displacement can cause cord injury or epidural haematoma, so any neck pain after a fall in these patients needs CT.
Ankylosed spine fractures
Fused but osteoporotic spine
Long lever arms
Fracture through all three columns
Cervicothoracic junction, unstable
Remember Neck pain after a minor fall in AS needs CT.
Exam trap Do not force a kyphotic AS neck into a neutral position for immobilisation; splint it in its usual posture.
Why the other options are wrong
The spinal canal is congenitally wide The canal is not congenitally wide; space is often reduced.
The disc spaces are unusually mobile The fused discs are rigid, not mobile, which is the problem.
The vertebral arteries are always occluded Vertebral artery injury can occur but is not always present and is not the main reason.
Bone density is increased throughout the spine Bone density is reduced, making the fused spine brittle.
Question 12Hard
Unconscious proprioception from the upper limb reaches the cerebellum through the inferior cerebellar peduncle as the posterior external arcuate fibres. In which nucleus do these fibres arise?
Answer: Accessory cuneate nucleus
Proprioceptive fibres from the upper limb and neck enter above T1, so they cannot use Clarke's column, which extends only from C8 to L3. They ascend in the fasciculus cuneatus to the accessory (lateral) cuneate nucleus in the medulla. Fibres from this nucleus form the cuneocerebellar tract, also called the posterior external arcuate fibres, and enter the cerebellum on the same side through the inferior peduncle. The nucleus cuneatus itself relays conscious proprioception to the thalamus through the medial lemniscus.
Cuneocerebellar tract
Upper limb unconscious proprioception
Relay: accessory cuneate nucleus
Posterior external arcuate fibres
Enters ipsilateral inferior peduncle
Remember Arm proprioception to the cerebellum: accessory cuneate nucleus.
Exam trap The accessory cuneate nucleus is the upper-limb equivalent of Clarke's column, not of the nucleus cuneatus.
Why the other options are wrong
Nucleus cuneatus Relays conscious sensation to the thalamus via the medial lemniscus.
Nucleus dorsalis (Clarke) Gives the dorsal spinocerebellar tract for the lower limb and trunk.
Inferior olivary nucleus Gives climbing fibres that cross to the opposite cerebellum.
Nucleus gracilis Relays conscious sensation from the lower limb.
