NucMed Boards Prep
IMAGE INTERPRETATION · LUNG V/Q IMAGING

V/Q Scan vs CTPA for Pulmonary Embolism in Pregnancy

Lung perfusion scintigraphy — normal study in a young female patient
Lung perfusion scintigraphy — normal study in a young female patient

CC BY-SA 4.0 · Wikimedia Commons · source file

Question

A 28-year-old pregnant patient (32 weeks gestation) presents with dyspnea and pleuritic chest pain. Duplex ultrasound is negative for DVT. Which imaging modality is PREFERRED for evaluating PE in this patient?

  1. ACT pulmonary angiography (CTPA) — always preferred in all populations
  2. BMRI of the chest — no radiation
  3. CV/Q lung scan — lower radiation dose to the fetus compared to CTPA, and lower maternal breast radiation
  4. DEmpiric anticoagulation without imaging
Show the answer and explanation

C. V/Q lung scan — lower radiation dose to the fetus compared to CTPA, and lower maternal breast radiation

In pregnant patients being evaluated for PE, the V/Q lung scan delivers LOWER radiation dose to the fetus (estimated 0.01–0.13 mGy) compared to CTPA (0.3–0.66 mGy) and also delivers significantly LOWER radiation dose to the maternal breast (important to minimize lifetime breast cancer risk). If the chest X-ray is normal, a V/Q scan is generally preferred in pregnant patients. If the CXR is abnormal (showing infiltrate, effusion, atelectasis), CTPA may be preferred to avoid indeterminate V/Q results. Either test is acceptable — the decision should be individualized based on CXR appearance, clinical probability, and institutional protocols.

More lung v/q imaging images

Lung scintigraphy — ventilation and perfusion imagesVentilation Agents: Tc-99m DTPA Aerosol vs Xe-133 V/Q lung scan — ventilation and perfusion projectionsIntermediate-Probability V/Q Scan Lung perfusion scintigraphy — Tc-99m MAA scanBrain and Kidney MAA Uptake: Right-to-Left Shunt Lung perfusion scintigraphy — MAA preparation and injectionTc-99m MAA Injection Technique V/Q lung scan — high probability for PEPIOPED II: High-Probability V/Q with High Pretest Probability V/Q lung scan — wedge-shaped peripheral perfusion defectWedge-Shaped Pleural-Based Defect: Pulmonary Embolism
← V/Q Scan in COPD: Matched DefectsVentilation Agents: Tc-99m DTPA Aerosol vs Xe-133 →

All 130 nuclear medicine images by category →

Practise image interpretation in the app

All 130 images as an interactive quiz, alongside 500 NMTCB and ARRT(N) questions with worked explanations, case studies and timed mock exams. 25 questions are free, no card and no account.

Start free — no card

Download on the App StoreGet it on Google Play