A 58-year-old man with a 40 pack-year smoking history presents with a 3-week history of persistent cough and haemoptysis. Chest X-ray shows a 4 cm irregular opacity in the right upper lobe with possible hilar lymphadenopathy. What is the most appropriate next imaging investigation?

## Investigation of Choice for Suspected Lung Malignancy ### Clinical Scenario A middle-aged smoker with persistent cough, haemoptysis, and a suspicious lung opacity on CXR raises concern for **primary lung cancer**. The next step is to characterize the lesion, assess mediastinal involvement, and stage the disease. ### Why Contrast-Enhanced CT (CECT) Chest is the Standard Next Step **Key Point:** CECT chest with IV contrast is the **imaging modality of choice** for characterizing a suspicious lung lesion and initial staging of suspected lung cancer [cite:Harrison 21e Ch 105]. **High-Yield:** CECT chest provides: 1. **Lesion characterization** — size, density, margins (spiculated vs. smooth), and enhancement pattern 2. **Mediastinal assessment** — evaluates hilar and mediastinal lymph nodes (short axis >1 cm is suspicious) 3. **Local staging** — determines chest wall, pleural, or pericardial involvement (T-staging) 4. **Distant metastases screening** — detects liver, adrenal, and bone metastases in the same acquisition 5. **Treatment planning** — guides biopsy approach and surgical candidacy 6. **Rapid acquisition** — provides comprehensive information without delay ### Why Other Modalities Are Not First-Line | Modality | Role & Limitation | | --- | --- | | **PET-CT** | Used **after** CECT to assess metabolic activity and detect distant metastases; not the initial characterization tool; adds cost and radiation | | **Lateral/oblique CXR** | Provides limited additional detail; does not characterize lesion or assess mediastinum adequately | | **Bronchoscopy** | Used for **tissue diagnosis** (biopsy/brushing) after imaging; not an imaging modality; reserved after CECT staging | **Mnemonic:** **CECT-First for Lung Cancer** — Characterization, Extent, Complications, Treatment planning. ### Imaging Protocol for Lung Cancer Workup ```mermaid flowchart TD A[Suspicious lung lesion on CXR]:::outcome --> B[CECT chest with IV contrast]:::action B --> C{Findings suggestive of malignancy?}:::decision C -->|Yes| D[Assess resectability & staging]:::action D --> E[PET-CT for metastases & FDG uptake]:::action C -->|No| F[Follow-up imaging or alternative diagnosis]:::action E --> G[Tissue diagnosis: CT-guided biopsy or bronchoscopy]:::action G --> H[Histology + staging = treatment planning]:::outcome ``` **Clinical Pearl:** IV contrast is essential in CECT chest for lung cancer workup because it enhances mediastinal structures and lymph nodes, improving conspicuity of nodal involvement and vascular invasion. ### Why Bronchoscopy Is Not the Next Step Bronchoscopy is a **diagnostic (tissue) procedure**, not an imaging modality. It is performed **after** CECT staging to obtain a biopsy or brushings for histological diagnosis. Performing bronchoscopy before CECT would miss critical staging information.