sophisticated imaging modalities have been introduced in the
recent years. However the simple plain chest X-ray is still the
most popular and the most important method to evaluate pulmonary
lesions as the entrance of all those new imaging methods which
may not be necessary in many occasions.
On the other hand, a large amount of new information has been provided to explain various sings and specific findings seen on the chest X-ray by those new modalities.
There are two steps to read the chest X-ray. They are 1) to detect abnormality and 2) to differentiate it as effective information for clinical usage.
To detect abnormal findings, many classical signs should be used. Silhouette sign along the mediastinal borders and diaphragmatic margins must be the most important to detect pulmonary abnormality on chest X-ray. Careful search in the specific areas hidden by the mediastinal shadow or diaphragametic domes is another important key to avoid overlook abnormal findings in the lungs with using anatomical knowledge provided by CT .
To differentiate abnormal radiographic findings, six categories based on the ICR code will be proposed. These will remind you very logical approach to differentiate particular X-ray findings. They include followings: 1) technical, 2) normal, 3) congenital, 4) inflammatory, 5) neoplastic, 6) traumatic or iatrogenic. When considering the differential diagnosis for certain abnormal findings, I always remind these categories one by one and go to the process to make differential diagnosis. This process includes three steps; 1) To make a list of diseases or conditions as many as possible in each category, 2) To exclude a specific disease or condition one by one from the list, 3) To leave those not to be excluded by former steps. All the process may be done at the same time, but it is very important to follow this process exactly. Incorrect diagnosis will be lead most often when the correct diagnosis was not included in the list of differential diagnoses from the beginning.