Examkin

Question

Difficulty: HardOrdering Imaging Studies

A 62-year-old man with a 35-pack-year smoking history schedules an appointment at a primary care office. He was recently informed that a baseline chest radiograph, required for a life insurance policy, revealed a 1.4-cm non-calcified opacity in the left upper lobe. He is completely asymptomatic and denies any history of malignancy, weight loss, or hemoptysis. His vital signs and physical examination are unremarkable. A comprehensive review of his electronic medical record reveals no prior chest imaging is available for comparison.

Assuming each successive investigation yields findings highly suspicious for a primary bronchogenic carcinoma, arrange the following imaging and image-guided diagnostic studies in the most appropriate chronological sequence for the comprehensive evaluation and systemic staging of this patient.

  1. 1Thin-section computed tomography (CT) of the chest without intravenous contrast
  2. 2Whole-body 18F-fludeoxyglucose positron emission tomography (FDG-PET) scan
  3. 3Endobronchial ultrasound (EBUS) with real-time guided transbronchial needle aspiration
  4. 4Magnetic resonance imaging (MRI) of the brain with intravenous gadolinium

Answer

The correct sequence for the diagnostic imaging and staging of a suspicious solitary pulmonary nodule is: 1) Thin-section CT of the chest without contrast, 2) Whole-body 18F-FDG PET scan, 3) Endobronchial ultrasound (EBUS) with guided needle aspiration, and 4) MRI of the brain with intravenous gadolinium.
The evaluation of a newly discovered solitary pulmonary nodule begins with a thin-section non-contrast CT of the chest to define its anatomic features. For a high-risk patient with a solid nodule larger than 8 mm, an 18F-FDG PET scan is sequentially ordered to evaluate metabolic activity and screen for extrathoracic disease. This is followed by an image-guided biopsy, such as EBUS-FNA, which provides both a tissue diagnosis and mediastinal lymph node staging. Finally, if lung cancer is confirmed, a contrast-enhanced MRI of the brain is ordered to complete the staging process by ruling out occult intracranial metastases prior to definitive treatment.

Step-by-Step Solution

1
Determine the initial characterization modality for a new pulmonary nodule found on radiography.
Thin-section CT of the chest without contrast is selected.
Chest radiography lacks the resolution to fully characterize a nodule. A non-contrast CT is required to evaluate the nodule's size, borders, attenuation, and calcification pattern, and to establish a precise baseline.
2
Select the appropriate imaging study to assess the risk of malignancy and regional spread for a high-risk solid nodule >8 mm.
Whole-body 18F-FDG PET scan is selected.
Once CT confirms a suspicious solid lesion >8 mm in a high-risk patient, a PET scan evaluates the metabolic avidity of the primary tumor and screens for occult regional and distant metastases, which guides the biopsy approach.
3
Identify the best modality for tissue diagnosis and mediastinal staging.
Endobronchial ultrasound (EBUS) with guided needle aspiration is selected.
Following a suspicious PET scan, an image-guided biopsy is necessary. EBUS-FNA is preferred as it allows for direct visualization and sampling of the primary lesion and systematic sampling of mediastinal lymph nodes for accurate N-staging.
4
Determine the necessary preoperative staging imaging for confirmed lung cancer.
MRI of the brain with intravenous gadolinium is selected.
If the biopsy confirms non-small cell lung cancer (NSCLC) and the patient is a candidate for curative resection, an MRI of the brain is required to exclude asymptomatic cerebral metastases, as the brain is a common site of spread not adequately evaluated by PET.

Key Concept

The diagnostic and staging sequence for a suspicious solitary pulmonary nodule >8 mm involves initial anatomic characterization with non-contrast CT, metabolic assessment with FDG-PET, definitive tissue diagnosis via image-guided biopsy (e.g., EBUS), and complete systemic staging including brain MRI if malignancy is confirmed.
Estimated Time:2m 0s
Rate this question

Topics

Ordering Imaging Studies

More questions from this topic