How can a computed tomography (CT) scan of the chest be justified in a patient with dyspnea, given a chest X-ray (CXR) showing an abnormal, coarse, and prominent interstitium consistent with chronic lung disease?

From the Guidelines

To justify ordering a CT chest in a patient with dyspnea and an abnormal chest X-ray showing coarsened prominent interstitium consistent with chronic lung disease, document specific clinical indications that warrant further evaluation, as the CT chest is medically necessary to better characterize the pattern of interstitial disease and assess disease distribution and severity. The chest X-ray has identified interstitial abnormalities but cannot fully characterize the specific type of interstitial lung disease, disease extent, or presence of complications 1. The CT chest is essential for proper diagnosis and management of interstitial lung disease in symptomatic patients, potentially avoiding more invasive diagnostic procedures like lung biopsy.

Key Points to Consider

• The patient's specific symptoms, such as dyspnea severity, duration, and progression, should be documented, along with relevant clinical findings like crackles and hypoxemia 1.
• The CT findings will impact management decisions regarding treatment initiation, medication selection, or referral to pulmonary specialists.
• CT imaging provides superior resolution of lung parenchyma compared to X-ray, making it a crucial tool for characterizing the pattern of interstitial disease (whether it's predominantly fibrotic, inflammatory, or mixed) and assessing disease distribution and severity 1.
• The presence and extent of HRCT imaging features of diffuse lung disease may also serve as important prognostic variables, and multiple quantitative imaging techniques evaluating diagnosis and prognosis are based on CT imaging 1.

Clinical Indications for CT Chest

• Dyspnea severity and duration
• Presence of crackles or hypoxemia
• Need to characterize the pattern of interstitial disease
• Assessment of disease distribution and severity
• Identification of potential complications like pulmonary hypertension or superimposed infection
• Establishment of a baseline for future comparison 1

From the Research

Justification for Ordering a CT Chest in a Patient with Dyspnea

When a patient presents with dyspnea and a chest X-ray (CXR) shows abnormal coarsened prominent interstitium consistent with chronic lung disease, ordering a CT chest can be justified in several ways:

• Diagnostic Accuracy: According to 2, CT scan remains the gold standard for diagnosing lung diseases, including interstitial lung diseases, despite its limitations such as radiation exposure and the need for patient transportation.
• Suspected Pulmonary Origin: The American College of Radiology Appropriateness Criteria Expert Panel on Thoracic Imaging suggests that imaging, including CT scans, plays a crucial role in evaluating chronic dyspnea with suspected pulmonary origin 3.
• Combined Pulmonary Fibrosis and Emphysema (CPFE) Syndrome: Patients with CPFE syndrome, characterized by dyspnea, upper-lobe emphysema, and lower-lobe fibrosis, may require a CT scan for diagnosis and assessment of complications such as pulmonary hypertension and lung cancer 4, 5.
• Radiologist's Role: Radiologists play a crucial role in diagnosing and managing patients with CPFE syndrome, and CT scans are essential for detecting the heterogeneity of appearances and complications associated with this syndrome 5.