From the Guidelines
The CT chest is justified for a patient with dyspnea who has restrictive lung disease on PFTs and bibasilar scarring on previous chest X-ray, as it provides superior detail of lung parenchyma and can identify specific patterns of interstitial abnormalities. The reasoning for ordering this study is to evaluate the extent and progression of interstitial lung disease or fibrosis that may not be fully appreciated on plain radiographs, as suggested by the American College of Radiology Appropriateness Criteria for diffuse lung disease 1. CT imaging can help confirm the presence of airspace abnormalities consistent with acute exacerbation or acute deterioration of diffuse lung disease, and exclude alternative causes for worsening clinical symptoms, such as pneumothorax, infection, or malignancy 1. Additionally, CT can rule out other potential causes of dyspnea such as pulmonary embolism, early malignancy, or bronchiectasis that might be contributing to the patient's symptoms following exertion. The combination of restrictive PFTs and radiographic evidence of scarring creates medical necessity for more detailed imaging to guide appropriate management of the patient's shortness of breath, especially when symptoms are concerning enough to prompt further evaluation beyond the initial workup. Key considerations for ordering a CT chest in this context include:
- Evaluating the extent and progression of interstitial lung disease or fibrosis
- Identifying specific patterns of interstitial abnormalities
- Ruling out alternative causes of dyspnea
- Guiding appropriate management of the patient's shortness of breath. It is also worth noting that the ACR Appropriateness Criteria for chronic dyspnea of noncardiovascular origin suggest that CT without IV contrast is usually appropriate for the initial imaging of patients with chronic dyspnea and suspected interstitial lung disease, especially if the patient has a disease that predisposes to interstitial lung disease 2.
From the Research
Rationale for Ordering a CT Chest
When a patient presents with shortness of breath (SOB) after overexertion, with a previous chest X-ray (CXR) showing mild bibasilar scarring and restrictive lung disease on pulmonary function tests (PFTs), ordering a CT chest can be justified under the diagnosis of dyspnea. The reasoning for this is as follows:
- The patient's symptoms of SOB after overexertion could be indicative of an underlying condition that is exacerbating their existing lung disease, and a CT chest can help identify any potential causes such as parenchymal scarring or other pulmonary abnormalities 3.
- The presence of mild bibasilar scarring on the previous CXR suggests that the patient may have underlying lung disease, and the CT chest can provide more detailed information about the extent and nature of this scarring 3.
- The PFT results showing restrictive lung disease are consistent with the findings of the study by 3, which found that parenchymal scarring is associated with restrictive spirometric defects in patients with chronic thromboembolic pulmonary hypertension.
- The evaluation of a patient with shortness of breath should involve a comprehensive approach, including imaging studies such as CT scans, as recommended by 4.
- The CT chest can help to rule out other potential causes of the patient's symptoms, such as pulmonary embolism or other pulmonary abnormalities, and can provide valuable information for guiding further management and treatment.