# Ch20: Imaging Exam Case Review（影像考试病例复习）
Preparatory Mindset
The JNU Medical Imaging final examination uses case-based questions: 10 cases in the final exam (5 points each = 50). For every case you must answer: ① Imaging techniques used (MRI/CT/DR…), ② Location of the lesion, ③ Imaging features of the lesion, ④ Common causes of the disease, ⑤ Diagnosis and differential diagnosis — always in this order. The lab review deck gives the master case list you must know; this chapter consolidates every master case with its imaging signature.
Core Concepts
Master case list (from the official review deck — "very important!!!")
| Case | English | Imaging signature |
|---|---|---|
| 大叶性肺炎 | Lobar pneumonia | Lobar consolidation + air bronchogram + silhouette sign (S. pneumoniae) |
| 支气管扩张 | Bronchiectasis | Signet ring sign on HRCT; tram-track on CXR |
| 气胸 | Pneumothorax | Visceral pleural line, no lung markings beyond; mediastinal shift = tension |
| 肺结核 | Tuberculosis | Upper lobe apical/posterior cavitary disease, tree-in-bud; Ghon complex (primary) |
| 周围型肺癌 | Peripheral lung cancer | Solitary spiculated nodule (corona radiata), pleural tail |
| 中央型肺癌 | Central lung cancer | Hilar mass + Golden S sign; distal atelectasis/consolidation |
| 小肠梗阻 | Small bowel obstruction | Dilated small bowel >3 cm, stair-step air-fluid levels, collapsed colon |
| 肠穿孔 | Intestinal perforation | Pneumoperitoneum (free air under diaphragm on erect film) |
| 肝癌 | Liver cancer (HCC) | Arterial enhancement + portal venous washout + capsule + tumor thrombus |
| 肝血管瘤 | Hepatic hemangioma | Peripheral nodular enhancement → delayed fill-in; bright T2 |
| 肝转移瘤 | Hepatic metastases | Multiple hypodense lesions, rim enhancement, bull's-eye |
| 胃癌 | Stomach cancer | Filling defect, malignant ulcer (Carman meniscus), linitis plastica |
| 胰腺炎 | Pancreatitis | Acute: enlarged pancreas + fat stranding + fluid; chronic: ductal calcification |
| 肾结石 | Kidney stones | CT gold standard; 85% visible on plain film; staghorn calculus |
| 输尿管结石 | Ureteral calculi | CT: stone + hydronephrosis |
| 肾癌 | Kidney cancer (RCC) | Solid enhancing renal mass; heterogeneous; may invade renal vein/IVC |
| 膀胱癌 | Bladder cancer | Bladder mass on US/CT; MRI for staging |
| 脑梗死 | Cerebral infarction | Low density in vascular territory (MCA most common); DWI restricted |
| 硬膜外血肿 | Epidural hematoma | Lentiform, doesn't cross sutures, skull fracture |
| 硬膜下血肿 | Subdural hematoma | Crescentic, crosses sutures; acute hyperdense |
| 基底节区脑出血 | Cerebral hemorrhage (basal ganglia) | Hyperdense mass (hypertension most common) |
| 蛛网膜下腔出血 | Subarachnoid hemorrhage | Hyperdense blood in basal cisterns/sulci (aneurysm) |
| 脑膜瘤 | Meningioma | Extra-axial, dural tail, homogenous enhancement, hyperostosis |
| 脑转移瘤 | Brain metastases | Gray-white junction, small nodule large edema, rim enhancement |
| 鼻咽癌 | Nasopharyngeal carcinoma | NP mass obliterating pharyngeal recess + skull base destruction + necrotic nodes |
| Colles骨折 | Colles' fracture | Distal radius fracture, posterior displacement (dinner-fork) |
| 青枝骨折 | Greenstick fracture | Incomplete fracture in children |
| 股骨颈骨折 | Fracture of neck of femur | Shenton's line interruption; impacted/trabecular disruption |
| 肱骨骨折 | Fracture of humerus | Humeral neck fracture (elderly) |
| 骨巨细胞瘤 | Giant cell tumour of bone | Subarticular eccentric expanding lesion (knee/wrist) |
| 骨肉瘤 | Osteosarcoma | Metaphysis (knee), sunray + Codman's triangle, 5–20 y |
| 骨软骨瘤 | Osteochondroma | Cartilage-capped exostosis |
| 主动脉夹层 | Aortic dissection | CTA: intimal flap, true/false lumen (Stanford/DeBakey) |
The universal 5-question answer template (for any case)
- Imaging technique: "This is a CT/CXR/MRI — [state the modality and view]."
- Location: "The lesion is located in [e.g. right upper lobe / left basal ganglia / distal radius]."
- Imaging features: describe density/signal, margins (well/ill-defined), calcification, cavitation, enhancement, mass effect — be systematic.
- Common causes / DDx: give 2–3 with the discriminating feature.
- Diagnosis: state the most likely diagnosis and the one sign that clinches it; add the differential you would exclude.
Exam question format (review deck)
- Questions: imaging techniques (MRI/CT/DR), location of the lesion, imaging features, common causes, diagnosis and differential diagnosis "and so on…".
- Previous exam examples: add left/right; add the examination location — i.e. be precise about side and site.
High-Yield Points
- Key Point: 10 cases × 5 pts = 50 in the final exam; answer in fixed order (technique → location → features → causes → diagnosis/DDx).
- Key Point: Consolidation + air bronchogram = pneumonia; pleural line without lung markings = pneumothorax; free air under diaphragm = perforation.
- Key Point: HCC = arterial ↑ / venous washout; hemangioma = peripheral fill-in; mets = rim enhancement.
- Key Point: EDH lentiform (doesn't cross sutures) vs SDH crescentic (crosses sutures); ICH = hypertension (basal ganglia).
- Key Point: NPC = pharyngeal recess obliteration + skull base erosion + necrotic nodes.
- Key Point: Osteosarcoma = sunray + Codman's (metaphysis, knee); GCT = subarticular eccentric; Colles' = dinner-fork.
- Key Point: Aortic dissection = intimal flap on CTA; classify Stanford/DeBakey.
- Key Point: Always specify side (left/right) and exact location — the exam explicitly tests this.
LMCHK OSCE Practice（OSCE & LMCHK）
- The LMCHK non-interactive imaging stations map to these master cases: chest X-ray of pneumothorax; CT findings of stroke and subarachnoid hemorrhage; hip x-ray; fibula/ankle x-ray; femoral shaft tumour; vertebral/spine x-ray; CT abdomen of adrenal glands; HCC; breast mass. Practice the same 5-step description for each.
- Add the LMCHK pediatric ortho list: clubfoot, scoliosis, DDH, pediatric fracture, septic arthritis.
- For any case: state the best next test (e.g. CTPA for PE, DWI for early stroke, non-contrast CT for renal colic, MRI for cord compression) — this is what examiners probe beyond describing the image.
Topic Summary
The imaging exam is case-based: 10 cases, 5 points each, answering technique → location → features → causes → diagnosis/DDx in order, always with left/right and exact site. The 33 master cases span chest (pneumonia, bronchiectasis, pneumothorax, TB, lung cancers), abdomen (SBO, perforation, HCC, hemangioma, mets, gastric cancer, pancreatitis), GU (stones, RCC, bladder cancer), neuro (infarction, EDH/SDH, ICH, SAH, meningioma, mets, NPC), MSK (Colles', greenstick, femoral neck, GCT, osteosarcoma, osteochondroma) and CVS (aortic dissection). Master the signature sign for each, and keep the LMCHK imaging-station overlap in mind.