Image MCQ: CT Thorax and Mediastinum for NEET PG (Lymphadenopathy, Aortic Dissection, PE, Tension Pneumothorax, UIP vs NSIP)
5 CT thorax MCQs for NEET PG: mediastinal LN patterns (TB, sarcoid, lymphoma), Stanford aortic dissection A vs B, saddle PE, tension pneumothorax deep sulcus sign, UIP vs NSIP in ILD.
Dr. NEETPGAI Editorial TeamPublished 15 Jul 202628 min read
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This content is for educational purposes for NEET PG exam preparation. It is not a substitute for professional medical advice, diagnosis, or treatment. Clinical information has been reviewed by qualified medical professionals.
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CT thorax and mediastinum contribute 4-6 image MCQs per NEET PG paper, spanning radiology, medicine, and surgery. Five patterns recur reliably:
Mediastinal lymphadenopathy patterns — TB (necrotic centre plus rim enhancement, right paratracheal and subcarinal), sarcoidosis (bilateral symmetric hilar plus right paratracheal — 1-2-3 sign, non-necrotic), lymphoma (bulky anterior mediastinal mass, mass effect), metastasis (asymmetric, primary present)
Acute aortic dissection — Stanford A vs Stanford B — A = ascending, surgical emergency; B = descending, medical first (labetalol, target SBP 100-120 and HR less than 60), TEVAR for complicated B
Massive pulmonary embolism — saddle embolus filling defect at main PA bifurcation, RV to LV ratio greater than 1, septal bowing, IVC contrast reflux, PA trunk greater than 29 mm; thrombolysis if hypotensive
Tension pneumothorax — deep sulcus sign on supine, mediastinal shift, depressed diaphragm, absent lung markings, subcutaneous emphysema; needle thoracostomy at 2nd ICS mid-clavicular line (or 4-5th ICS mid-axillary per ATLS 2010)
UIP vs NSIP pattern in ILD — UIP = basal subpleural reticulation, honeycombing, traction bronchiectasis, IPF (median survival 3-5 y, anti-fibrotic pirfenidone or nintedanib); NSIP = basal ground-glass, fine reticulation, subpleural sparing, no honeycomb, CTD-associated, responds to immunosuppression
Locking these 5 patterns plus 5-10 CXR classics (TOF boot-shape, TGA egg-on-side, coarctation figure-of-3, miliary TB, ARDS) over 2-3 weeks moves accuracy from 40 to 80 percent in thoracic imaging MCQs.
Why CT thorax MCQs are high-yield for NEET PG
CT thorax overlaps radiology, medicine, cardiology, oncology, surgery, and emergency medicine — five subjects that together account for 60-70 percent of the NEET PG paper. Modern medicine has moved decisively from CXR-first to CT-first for chest emergencies (aortic dissection, PE, complex trauma), so NBEMS increasingly tests CT patterns rather than only CXR. Additionally, INI-CET has a stronger radiology bias and includes 3-5 dedicated CT thorax MCQs per paper.
The 5 patterns below account for the majority of CT thorax image MCQs across 2019-2024 papers.
Systematic CT thorax read
Before answering any CT thorax MCQ, apply this quick read.
Lymph nodes (Fleischner size cut-off 10 mm short axis), thymus, oesophagus, great vessels, trachea
Compartments (anterior, middle, posterior)
Lungs
Distribution (upper vs lower, central vs peripheral), pattern (nodular, cavitary, reticular, ground-glass, honeycomb), signs (halo, tree-in-bud, crazy paving)
Rib fractures, lytic or blastic lesions, subcutaneous emphysema
Trauma vs metastasis clues
MCQ 1: 48-year-old woman with chronic cough, weight loss and hilar lymphadenopathy
Image description:[Contrast-enhanced axial CT thorax at the level of the aortic arch and carina of a 48-year-old woman with 3 months of dry cough, fatigue, and 4 kg weight loss. The image shows bilateral symmetric hilar lymphadenopathy and prominent right paratracheal lymphadenopathy — the classic 1-2-3 Garland triad. The lymph nodes are homogeneous soft-tissue density without central low-density necrosis and show homogeneous mild enhancement. A separate coronal reformat shows the symmetric bilateral hilar prominence and right paratracheal fullness. The lung parenchyma shows subtle upper-lobe reticulonodular changes clustered along the bronchovascular bundles (perilymphatic distribution). No pleural effusion. No cavitation. No calcification within nodes (yet — chronic disease may develop egg-shell calcification).]
Clinical vignette: A 48-year-old woman, non-smoker, presents with 3 months of dry cough, low-grade fatigue, and 4 kg weight loss. She reports mild bilateral ankle swelling for 2 weeks and a painless red plaque on the left shin that has been present for 4 weeks. She has no fever, no night sweats, and no haemoptysis. Occupational history — school teacher, no dust or asbestos exposure. Family history — mother had "some lung problem" of unclear diagnosis. Examination: BMI 26, no lymphadenopathy palpable, chest clear, mild bilateral erythema nodosum on the anterior shins, no clubbing. Labs — Hb 12.4, WBC 7,200, platelets 340,000, ESR 45 mm/hr, corrected calcium 10.9 mg/dL (mildly raised), ACE level 92 U/L (raised), Mantoux 5 mm at 48 h.
Options:
(a) Sarcoidosis
(b) Tuberculous lymphadenitis
(c) Hodgkin lymphoma
(d) Metastatic lung cancer
Correct answer: (a) Sarcoidosis
Reasoning: The 1-2-3 sign (bilateral symmetric hilar plus right paratracheal lymphadenopathy) on CT thorax in a middle-aged non-smoking woman with erythema nodosum, hypercalcaemia, raised ACE, and a perilymphatic upper-lobe nodular pattern is textbook stage II pulmonary sarcoidosis (Scadding staging — stage 0 normal, I hilar LN alone, II hilar LN plus parenchymal, III parenchymal alone, IV fibrosis). The lymph nodes are non-necrotic and homogeneously enhancing — sarcoid granulomas are non-caseating.
Tuberculous lymphadenitis produces asymmetric hilar and paratracheal nodes with central caseation necrosis and rim enhancement on contrast CT — a distinct pattern. Hodgkin lymphoma produces bulky anterior mediastinal masses with mass effect on adjacent structures. Metastatic lung cancer would show an identifiable primary lung mass and asymmetric drainage-station lymphadenopathy.
Teaching pearl — mediastinal lymphadenopathy differential:
Diagnosis
LN pattern
Key CT clues
Confirmation
Sarcoidosis
Bilateral symmetric hilar plus right paratracheal (1-2-3 sign)
Non-necrotic, homogeneous, egg-shell calcification in chronic disease; perilymphatic parenchymal nodules
Non-caseating granulomas on biopsy, raised ACE
TB
Asymmetric, right paratracheal and subcarinal predominant
Central low-density necrosis, rim enhancement, upper-lobe cavitation, tree-in-bud
AFB, GeneXpert, culture
Lymphoma (HL, NHL)
Bulky anterior mediastinum, crosses midline
Homogeneous soft tissue, mild enhancement, mass effect on airway and SVC
Excisional LN biopsy
Metastatic (lung, breast, oesophageal, GI)
Asymmetric, drainage-station specific
Primary tumour visible, heterogeneous enhancement
PET-CT, primary biopsy
Silicosis / coal worker
Bilateral hilar with characteristic egg-shell calcification
Occupational exposure, upper-lobe fibrosis with progressive massive fibrosis
Occupational history plus HRCT
Castleman disease
Solitary or multicentric
Intensely enhancing hypervascular nodes
Excisional biopsy
MCQ 2: 62-year-old hypertensive with sudden tearing chest pain radiating to the back
Image description:[Contrast-enhanced CT angiography of the aorta of a 62-year-old man with sudden severe tearing anterior chest pain radiating to the interscapular region 90 minutes before imaging. The axial image at the level of the aortic arch shows a curvilinear intimal flap separating the true lumen (smaller, brighter, well-opacified) from the false lumen (larger, lower-density due to slower contrast filling) in the ascending aorta. The dissection extends distally into the aortic arch and descending thoracic aorta on the sagittal and coronal reformats. A small pericardial effusion is present (indicating early leak). The aortic root diameter is 4.6 cm. The origins of the great vessels (innominate, left CCA, left subclavian) appear patent on this study but the false lumen partially opacifies. No mediastinal haemorrhage yet. LV chamber size normal. No pleural effusion.]
Clinical vignette: A 62-year-old male labourer with a 15-year history of poorly controlled hypertension (on irregular amlodipine, missed doses for a week) presents to the emergency 90 minutes after sudden severe tearing anterior chest pain that migrated to the interscapular region and then down to the lumbar region. Pain was 10/10 at onset. He has diaphoresis, mild dyspnoea, no cough, no haemoptysis. Examination: pulse 108/min regular, BP 178/104 on the right arm, BP 152/88 on the left arm (a 26 mmHg systolic difference), JVP normal, S1 S2 normal, a soft early diastolic murmur at the left sternal border (aortic regurgitation), chest clear, abdomen soft, pulses full and symmetric in the femorals. ECG — sinus tachycardia, no ST-T changes. Troponin negative. D-dimer 4,500 ng/mL (raised).
Options:
(a) Stanford A aortic dissection
(b) Stanford B aortic dissection
(c) Aortic intramural haematoma
(d) Massive pulmonary embolism
Correct answer: (a) Stanford A aortic dissection
Reasoning: The classic vignette — sudden tearing chest pain radiating to the back, hypertensive middle-aged male, inter-arm BP difference greater than 20 mmHg, new aortic regurgitation murmur, pericardial effusion on CT — is aortic dissection. The CT shows an intimal flap in the ascending aorta = Stanford A (regardless of distal extension). Stanford A is a surgical emergency — untreated mortality is approximately 1 to 2 percent per hour in the first 48 hours from rupture into the pericardium (cardiac tamponade), acute severe aortic regurgitation, coronary ostial occlusion (acute MI, most commonly the RCA giving inferior MI), or stroke from arch vessel malperfusion.
Stanford B is confined to the descending aorta distal to the left subclavian and is managed medically first (aggressive BP and HR control with IV labetalol or esmolol — target systolic 100-120 mmHg and HR less than 60), with TEVAR for complicated cases.
Intramural haematoma has crescentic wall thickening without a flap. Massive PE would show a filling defect in the pulmonary arteries — the vignette clues (tearing radiating pain, inter-arm BP difference, AR murmur) point to dissection.
Teaching pearl — the Stanford vs DeBakey classification:
Stanford A = ascending aorta involved (with or without descending); surgical emergency
Stanford B = descending aorta only, distal to left subclavian; medical first
DeBakey I = ascending plus descending = Stanford A
DeBakey II = ascending only = Stanford A
DeBakey III = descending only = Stanford B
Emergency management pathway:
Two large-bore IV access, arterial line (right radial preferred if left subclavian is involved)
IV opioids for pain (relieving pain reduces sympathetic drive)
IV beta-blocker first (labetalol or esmolol) to reduce heart rate below 60 and blood pressure to systolic 100-120 mmHg — reducing dP/dt is the primary therapeutic goal
Add IV vasodilator (nitroprusside or nicardipine) only after adequate beta-blockade (never vasodilator alone — reflex tachycardia worsens shear stress)
Emergent cardiothoracic surgery consult for Stanford A
TEVAR for complicated Stanford B (visceral or limb malperfusion, refractory pain, rupture, refractory hypertension, rapid expansion)
Avoid thrombolysis and antiplatelets in dissection — bleeding into the false lumen is catastrophic
MCQ 3: 55-year-old with sudden dyspnoea 7 days after knee arthroplasty
Image description:[Contrast-enhanced CT pulmonary angiography of a 55-year-old woman on post-operative day 7 after total knee replacement, presenting with acute dyspnoea, pleuritic chest pain, and haemodynamic instability. The axial image at the pulmonary artery bifurcation shows a large filling defect straddling the main pulmonary artery bifurcation and extending into both the right and left main pulmonary arteries — the classic saddle embolus. Secondary findings include a dilated main pulmonary artery trunk measuring 34 mm (normal less than 29 mm), right ventricular dilation with RV to LV ratio 1.4 on short-axis reformat (right RV pushing the interventricular septum into the LV), interventricular septal bowing, and contrast reflux into the IVC and hepatic veins through a functionally regurgitant tricuspid valve. Small right pleural effusion. No consolidation. No cavitation.]
Clinical vignette: A 55-year-old woman with obesity (BMI 34) is 7 days post total knee replacement. She was mobilising well until this morning when she developed acute breathlessness while walking to the bathroom, pleuritic right-sided chest pain, and a single episode of near-syncope. On presentation: pulse 128/min, BP 84/56 (marked hypotension), RR 32/min, SpO2 88 percent on room air improving to 94 percent on 6 L oxygen. She is diaphoretic, alert but anxious. JVP raised to 8 cm, right ventricular heave, loud P2, no murmur. Left calf is unilaterally swollen (28 cm midcalf vs 24 cm on the right) and tender. ECG — sinus tachycardia, S1Q3T3 pattern, RBBB. Troponin 0.24 (mildly raised — indicates RV strain), NT-proBNP 3400 pg/mL. D-dimer 8,400 ng/mL. Wells score 6 (high probability).
Options:
(a) Massive pulmonary embolism with RV strain
(b) Submassive pulmonary embolism
(c) Pneumonia with sepsis
(d) Cardiac tamponade
Correct answer: (a) Massive pulmonary embolism with RV strain
Reasoning: The vignette is classic — recent orthopaedic surgery, unilateral calf swelling (DVT source), sudden dyspnoea, pleuritic pain, near-syncope, hypotension (SBP 84 mmHg — sustained hypotension SBP less than 90 defines massive PE), tachycardia, S1Q3T3, RBBB, and raised troponin. The CTPA shows a saddle embolus with imaging signs of RV strain — RV to LV ratio 1.4, septal bowing, IVC contrast reflux. This is massive (high-risk) PE.
Submassive PE is normotensive but with imaging or biomarker evidence of RV strain (RV to LV ratio at or above 1, raised troponin or BNP). The hypotension in this vignette upgrades to massive.
Pneumonia would show consolidation on CT. Cardiac tamponade would show pericardial effusion with tamponade physiology (RA collapse, RV diastolic collapse) — not present.
Teaching pearl — PE risk stratification and treatment:
Category
Definition
Treatment
Massive (high-risk)
Sustained hypotension SBP less than 90 mmHg or drop 40 mmHg, cardiac arrest, shock
Systemic thrombolysis (alteplase 100 mg over 2 h) plus heparin; catheter or surgical embolectomy if thrombolysis contraindicated
Submassive (intermediate-risk)
Normotensive with RV strain (RV-LV ratio at or above 1, raised troponin or BNP)
Heparin plus close monitoring; consider catheter-directed thrombolysis for selected patients
CTPA signs of RV strain — RV to LV ratio at or above 1, septal bowing into LV, IVC contrast reflux, PA trunk greater than 29 mm — carry independent short-term mortality prediction.
MCQ 4: 24-year-old with chest trauma and sudden hypotension in the emergency
Image description:[Supine anteroposterior chest radiograph (portable) of a 24-year-old man 20 minutes after a road traffic accident with anterior chest wall impact against a steering column. The film shows an abnormally deep and radiolucent right costophrenic angle — the deep sulcus sign — with the diaphragm appearing depressed on the right. The right lung markings are absent in the periphery. The mediastinum is shifted to the left, the right hemidiaphragm is markedly depressed, and subcutaneous emphysema is visible in the right chest wall soft tissues as radiolucent striations. Two right-sided rib fractures are visible. A separate CT scout image shows the same findings with clear air outside the visceral pleura and confirms the mediastinal shift.]
Clinical vignette: A 24-year-old motorcyclist is brought to the trauma bay after a head-on collision at 60 km/h without a helmet. Primary survey: airway patent, RR 38/min laboured, breath sounds absent on the right, hyperresonant to percussion on the right, trachea deviated to the left, JVP raised. Pulse 138/min thready, BP 74/40, capillary refill 4 seconds. GCS 14. FAST scan negative for free fluid; extended FAST (thoracic view) confirms absence of lung sliding on the right.
Options:
(a) Tension pneumothorax
(b) Massive haemothorax
(c) Cardiac tamponade
(d) Flail chest
Correct answer: (a) Tension pneumothorax
Reasoning:Tension pneumothorax is a clinical diagnosis and should not wait for imaging — the vignette (absent breath sounds, hyperresonance, tracheal deviation away from the side, hypotension, raised JVP) is classic. Where a supine CXR is obtained, the deep sulcus sign (an abnormally deep radiolucent costophrenic angle because air layers anteriorly in the supine patient and outlines the sulcus) is the pathognomonic radiographic finding, along with mediastinal shift, hemidiaphragm depression, absent lung markings, and subcutaneous emphysema.
Massive haemothorax would produce dullness to percussion and CXR opacification. Cardiac tamponade would show muffled heart sounds, pulsus paradoxus, and pericardial effusion on ultrasound (not lung air). Flail chest is a chest wall injury with paradoxical movement of a free-floating segment — a separate entity.
Teaching pearl — needle thoracostomy anatomy:
Traditional site: 2nd intercostal space, mid-clavicular line, immediately above the 3rd rib (avoids the neurovascular bundle on the inferior surface of the 2nd rib)
ATLS updated site (2010): 4th or 5th intercostal space, mid-axillary line (the "safety triangle" — anterior latissimus dorsi, posterior pectoralis major, superior nipple line, inferior 5th ICS). Reason for the update — chest wall is thicker anteriorly in adults, and 30-50 percent of 2nd ICS needle thoracostomies fail to reach the pleural space
Use a large-bore (14-16 gauge) IV cannula at least 5 cm long
Definitive management is chest tube (28-32 Fr) at the mid-axillary line 4-5th ICS as soon as haemodynamics allow
Some current trauma guidelines favour finger thoracostomy over needle thoracostomy in the trauma bay (more reliable, larger bore) as a bridge to chest tube
MCQ 5: 58-year-old with progressive dyspnoea over 2 years and fine bibasal crackles
Image description:[High-resolution CT thorax (thin-slice, prone position, expiratory phase) of a 58-year-old man with 24 months of progressive exertional dyspnoea and dry cough. The axial image at the lung bases shows a basal and subpleural distribution of reticular abnormality with interlobular septal thickening, honeycombing (clustered subpleural cystic airspaces 3-8 mm in diameter arranged in multiple layers), and traction bronchiectasis (dilated bronchi coursing through the fibrotic zones). There is minimal ground-glass opacification. The upper lobes are relatively spared. A coronal reformat confirms the basal-predominant subpleural distribution. No pleural effusion, no lymphadenopathy, no mosaic attenuation.]
Clinical vignette: A 58-year-old retired man, ex-smoker (35 pack-years, quit 10 years ago), presents with 24 months of progressive dyspnoea on exertion (now MRC grade 3 — stops for breath after walking 100 m on level ground) and a dry non-productive cough. No fever, no haemoptysis, no orthopnoea, no PND. No occupational asbestos or bird-antigen exposure. No connective tissue symptoms (no Raynaud, no arthritis, no rash, no dysphagia). Examination: BMI 23, bibasal fine end-inspiratory Velcro crackles, mild clubbing, no cyanosis. Cardiovascular unremarkable. Labs — Hb 15.1, ANA negative, RF negative, anti-CCP negative, ENA panel negative, precipitins negative. PFT — restrictive pattern with FVC 62 percent predicted, FEV1/FVC 0.82, DLCO 46 percent predicted. 6-minute walk test — desaturation from 96 to 88 percent on room air.
Reasoning: The HRCT shows the four cardinal features of a definite UIP pattern — (1) basal-predominant distribution, (2) subpleural distribution, (3) honeycombing (the pathognomonic feature), and (4) traction bronchiectasis — with minimal or no ground-glass. In an older ex-smoker with a negative autoimmune panel and negative precipitins, this is idiopathic pulmonary fibrosis (IPF). Median survival 3-5 years from diagnosis. Management is anti-fibrotic therapy — pirfenidone or nintedanib (both slow FVC decline by roughly 50 percent), oxygen supplementation, pulmonary rehabilitation, and referral for lung transplantation in eligible patients under 65-70 years without severe comorbidity.
NSIP shows basal ground-glass with fine reticulation and subpleural sparing and characteristic absence of honeycombing — strongly associated with connective tissue disease. Hypersensitivity pneumonitis is centrilobular with mosaic attenuation and air trapping on expiratory HRCT (this patient has no exposure history and no mosaic). Sarcoidosis stage IV shows upper-lobe fibrosis with hilar retraction and traction bronchiectasis in the upper zones (opposite of UIP).
Teaching pearl — UIP vs NSIP HRCT contrast:
Feature
UIP (IPF, RA-ILD, chronic HP, asbestosis)
NSIP (CTD-ILD, idiopathic NSIP)
Distribution
Basal, subpleural
Basal, symmetric
Reticulation
Coarse, honeycombing
Fine, ground-glass predominant
Honeycombing
Yes, subpleural, multi-layered
No or minimal
Subpleural sparing
No (fibrosis hugs the pleura)
Yes (characteristic subpleural sparing)
Traction bronchiectasis
Yes
Yes
Ground-glass
Minimal
Prominent, especially in cellular NSIP
Prognosis
Poor (3-5 y median survival)
Good — cellular subtype 5-y survival above 80 percent; fibrotic subtype around 50 percent
Multidisciplinary discussion (radiology, pathology, pulmonology, rheumatology) — the gold-standard framework for ILD diagnosis
Surgical lung biopsy (video-assisted thoracoscopic) if HRCT pattern is indeterminate or the diagnosis is unclear after MDD
Cryobiopsy is an emerging less-invasive alternative in expert centres
India-specific considerations
TB remains the single most important cause of mediastinal lymphadenopathy in India — always exclude TB before labelling any hilar or mediastinal lymphadenopathy as sarcoid, especially in patients under 40. GeneXpert and AFB culture on lymph node aspirate are mandatory
Silicosis and coal worker's pneumoconiosis are common in Indian mining and stone-quarrying regions (Rajasthan, Jharkhand) — bilateral upper-lobe reticulonodular disease with egg-shell calcification of hilar nodes and progressive massive fibrosis
Rheumatic heart disease with pulmonary hypertension is still common in India; RHD-associated PH may show enlarged main PA and RV hypertrophy on CT thorax — do not confuse with primary pulmonary hypertension
CT thorax availability — most district hospitals now have 16-slice CT; CTPA requires contrast and adequate injector pumps; some rural centres still rely on V/Q scan or clinical scoring for PE
TEVAR availability for complicated Stanford B dissection is limited to metro cardiothoracic centres; interfacility transfer under BP control is the reality for district-hospital presentations
IPF prevalence in India is likely under-diagnosed; anti-fibrotic drug access has improved with generic pirfenidone and nintedanib but remains expensive; PMJAY (Ayushman Bharat) has begun including specific ILD packages in select states
Trauma epidemiology — road traffic accidents contribute the majority of tension pneumothorax cases; helmet non-compliance and lack of pre-hospital care exacerbate mortality; needle thoracostomy skill drills in emergency medicine training are increasing
How NEET PG tests CT thorax
Seven recurring patterns.
Pattern 1 — Mediastinal LN pattern recognition: Bilateral symmetric hilar plus right paratracheal LN with no necrosis = sarcoidosis (1-2-3 sign). Asymmetric necrotic LN with rim enhancement = TB. Bulky anterior mediastinal mass crossing midline = lymphoma.
Pattern 2 — Stanford aortic dissection: Intimal flap in ascending aorta = Stanford A, surgical emergency. Descending aorta only distal to left subclavian = Stanford B, medical first (labetalol, SBP 100-120, HR less than 60).
Pattern 3 — Saddle embolus: Filling defect straddling the main PA bifurcation with RV to LV ratio greater than 1, septal bowing, and IVC reflux = massive PE — thrombolysis if hypotensive.
Pattern 4 — Deep sulcus sign: Abnormally deep radiolucent costophrenic angle on supine CXR = tension pneumothorax — needle thoracostomy at 2nd ICS mid-clavicular OR 4-5th ICS mid-axillary (ATLS 2010).
Pattern 5 — UIP vs NSIP: Basal subpleural honeycombing with traction bronchiectasis and minimal ground-glass = UIP (IPF) — anti-fibrotic. Basal ground-glass with fine reticulation, subpleural sparing, no honeycomb, plus positive autoimmune panel = NSIP (CTD-ILD) — immunosuppression.
Pattern 6 — Pericardial vs pleural effusion: On CT the pericardial fluid is inside the pericardium and outlines the heart; pleural fluid is outside and outlines the lung. Rim enhancement of the pericardium plus effusion suggests pericarditis (TB in India until proven otherwise).
Pattern 7 — Airway signs: Tree-in-bud pattern in the peripheral lung = endobronchial spread of TB or bronchiolitis. Halo sign around a nodule = angioinvasive aspergillosis. Reverse halo sign = organising pneumonia.
High-yield one-liners:
Mediastinal LN cut-off = 10 mm in short axis; larger than this needs workup
Sarcoidosis stages 0-IV (Scadding); 1-2-3 sign is the classic radiographic clue
TB LN — necrosis plus rim enhancement, right paratracheal and subcarinal predominance
How do you differentiate the classic mediastinal lymphadenopathy patterns of TB, sarcoidosis, lymphoma and metastasis on CT thorax?
Mediastinal lymphadenopathy pattern recognition is a high-yield CT thorax cluster for NEET PG. Tuberculosis produces bulky lymph nodes with characteristic central low-density necrosis and rim enhancement on contrast CT — the necrosis reflects caseation, and the enhancement reflects the surrounding hyperaemic granulomatous rim. Distribution is asymmetric with a predilection for right paratracheal, subcarinal, and hilar stations. Sarcoidosis is the classic bilateral symmetric hilar and right paratracheal lymphadenopathy known as the 1-2-3 sign or Garland triad on chest X-ray (right paratracheal, right hilar, left hilar); on CT the nodes are non-necrotic, homogeneously enhancing, and often calcify with egg-shell calcification in chronic disease. Hodgkin and non-Hodgkin lymphoma produce bulky bilateral anterior mediastinal masses that displace and compress adjacent structures (SVC obstruction, tracheal deviation), often crossing the midline; nodes are homogeneous soft-tissue density with mild homogeneous enhancement and central necrosis only in bulky disease. Metastatic lymphadenopathy (from lung cancer, oesophageal cancer, breast cancer, or occasionally intra-abdominal primaries) is often unilateral, asymmetric, and associated with a primary tumour identifiable on the same study; distribution follows anatomic drainage of the primary. NEET PG tests the 1-2-3 pattern for sarcoid, the necrotic-with-rim-enhancement pattern for TB, and the bulky anterior mediastinal mass for lymphoma most frequently.
What is the Stanford classification of aortic dissection and why does it drive management immediately at presentation?
The Stanford classification of aortic dissection is the single most testable acute aortic emergency framework because it drives an immediate treatment decision. Stanford A involves the ascending aorta (with or without descending involvement) and is a surgical emergency — untreated mortality is approximately 1 to 2 percent per hour in the first 48 hours, driven by aortic rupture into the pericardium (cardiac tamponade), acute aortic regurgitation, coronary ostial occlusion (acute MI), or stroke from arch vessel malperfusion; emergent surgical repair (ascending aortic replacement with or without valve replacement) is indicated regardless of dissection extent. Stanford B is confined to the descending thoracic aorta distal to the left subclavian artery and is managed medically first — aggressive blood pressure and heart rate control with IV labetalol or esmolol (target systolic 100-120 mmHg and heart rate less than 60 beats per minute), pain control, and monitoring for complications; surgical or endovascular repair (TEVAR) is reserved for complicated Stanford B (visceral or limb malperfusion, refractory pain, rapid dissection expansion, rupture, or refractory hypertension). The older DeBakey classification divides into I (ascending plus descending), II (ascending only), and III (descending only) — I and II are Stanford A, III is Stanford B. CT angiography of the aorta shows the intimal flap separating the true and false lumens, the entry and re-entry tears, and any visceral malperfusion; it is the gold-standard investigation. NEET PG tests the Stanford A surgical vs Stanford B medical rule and the CT flap sign heavily.
What are the CT pulmonary angiography findings of massive pulmonary embolism and how do they guide treatment?
CT pulmonary angiography (CTPA) is the gold-standard investigation for suspected pulmonary embolism, with sensitivity 83-100 percent and specificity 89-98 percent depending on the vascular level of the embolus. The direct sign is a filling defect within a contrast-enhanced pulmonary artery — the classic saddle embolus straddles the main pulmonary artery bifurcation and extends into the right and left main branches, representing a massive PE with high right ventricular afterload. Indirect signs of RV strain are the RV to LV ratio greater than 1 (measured at the mid-ventricular short-axis level — an RV-LV ratio at or above 1 predicts short-term mortality and identifies submassive PE), interventricular septal bowing into the left ventricle, reflux of contrast into the IVC and hepatic veins (through a functionally regurgitant tricuspid valve), and pulmonary artery trunk dilatation greater than 29 mm. Management is stratified by haemodynamic status. Massive (high-risk) PE — sustained hypotension SBP less than 90 mmHg or a drop of 40 mmHg from baseline, cardiac arrest, or shock — needs systemic thrombolysis with alteplase 100 mg over 2 hours plus anticoagulation, or surgical or catheter embolectomy if thrombolysis is contraindicated. Submassive (intermediate-risk) PE — normotensive but with RV strain (dilated RV, raised troponin or BNP) — is managed with anticoagulation and monitored closely; selected patients receive catheter-directed thrombolysis. Low-risk PE is managed with anticoagulation alone (DOAC first-line — apixaban, rivaroxaban, dabigatran, edoxaban). NEET PG tests the saddle embolus, the RV-LV ratio greater than 1, and the massive vs submassive vs low-risk stratification most commonly.
What are the CXR and CT signs of tension pneumothorax and where is emergency needle thoracostomy performed?
Tension pneumothorax is a clinical diagnosis that should not wait for imaging — when suspected in an unstable patient, immediate needle thoracostomy or finger thoracostomy is life-saving. However, imaging is often obtained in ambulatory or partially compensated cases. The upright chest X-ray shows a visceral pleural line separated from the chest wall with absent lung markings beyond it, and in tension physiology there is mediastinal shift away from the affected side, depression of the ipsilateral hemidiaphragm, and widening of intercostal spaces. On a supine chest X-ray (common in trauma bays and ICUs) the classic finding is the deep sulcus sign — an abnormally deep and radiolucent costophrenic angle on the affected side because air layers anteriorly and outlines the sulcus; the visceral pleural line may not be visible. Subcutaneous emphysema often accompanies the pneumothorax, appearing as radiolucent striations in the chest wall soft tissue. CT thorax is highly sensitive for even small pneumothoraces and shows air outside the visceral pleura, mediastinal shift, and often the underlying cause (rib fracture, bullous emphysema, or iatrogenic lung injury). Emergency decompression is performed with a large-bore (14-16 gauge) IV cannula inserted at the 2nd intercostal space in the mid-clavicular line just above the 3rd rib (avoiding the neurovascular bundle on the inferior surface of the 2nd rib) — 2010 ATLS updated the alternative site to the 4th or 5th intercostal space in the mid-axillary line (safety triangle) because the chest wall in adults is thicker anteriorly and the 2nd ICS approach fails in 30 to 50 percent. NEET PG tests the deep sulcus sign, the needle thoracostomy anatomic sites, and the clinical diagnosis of tension physiology (hypotension, hyperresonance, absent breath sounds, tracheal deviation).
How do UIP and NSIP patterns differ on high-resolution CT and what do they imply about aetiology and prognosis?
The high-resolution CT (HRCT) distinction between usual interstitial pneumonia (UIP) and non-specific interstitial pneumonia (NSIP) is one of the highest-yield ILD questions on NEET PG. UIP is the histopathological pattern of idiopathic pulmonary fibrosis (IPF) and also occurs in rheumatoid arthritis, chronic hypersensitivity pneumonitis, asbestosis, and drug reactions. HRCT signs of a definite UIP pattern are (1) basal-predominant and subpleural distribution, (2) reticular abnormality (interlobular septal thickening), (3) honeycombing (clustered cystic airspaces with well-defined walls, 3-10 mm diameter, usually subpleural and in multiple layers), and (4) traction bronchiectasis — with no or minimal ground-glass opacification. Prognosis is poor with median survival 3-5 years from diagnosis in IPF; management is anti-fibrotic therapy (pirfenidone or nintedanib), oxygen support, and lung transplantation for advanced disease. NSIP has bilateral basal-predominant ground-glass opacification with fine reticulation and traction bronchiectasis but characteristic absence or paucity of honeycombing, and a subpleural sparing pattern (immediate subpleural lung is relatively spared, unlike UIP where honeycombing hugs the pleura). NSIP is strongly associated with connective tissue disease (systemic sclerosis, polymyositis or dermatomyositis with anti-synthetase syndrome, mixed connective tissue disease, Sjogren, RA) — always send an autoimmune panel (ANA, ENA, myositis panel, RF, anti-CCP). NSIP has a much better prognosis than UIP with 5-year survival above 80 percent for the cellular subtype and around 50 percent for the fibrotic subtype, and it responds to immunosuppression (steroids, mycophenolate, azathioprine). NEET PG tests the honeycombing distinction (UIP yes, NSIP typically no), the subpleural sparing of NSIP, and the CTD association of NSIP most commonly.
This content is for educational purposes for NEET PG exam preparation. It is not a substitute for professional medical advice, diagnosis, or treatment. Clinical information has been reviewed by qualified medical professionals.
Written by: NEETPGAI Editorial Team
Reviewed by: Pending SME Review
Last reviewed: July 2026
