Isodense shadows are foci that appear as dots, round-like, etc. at the site of a lesion with a density similar to that of the surrounding tissue, and are generally used to describe lung lesions. On imaging, they are generally categorized as high-density, isodense, and low-density, with lesions showing different densities depending on their composition. Usually, the judgment of the lesion is based on the density, size, morphology and relationship with the surrounding tissues, and sometimes further intensified examination is required to determine the nature of the lesion. Usually, the density of different substances is different, and isodense substances generally belong to the same substance. The image presented by a lesion with a density similar to that of the surrounding tissues is generally referred to as an isodense shadow. When isodense shadows appear in the examination, patients should consult the doctor in time to improve the next examination to determine the nature of the lesion and follow the doctor’s instructions for treatment to avoid delaying the condition.