Unsuspected pulmonary thromboemboli: a continuing clinical challenge.

The multidetector computed tomographic scanner has greatly improved our ability to quickly, safely, and adequately visualize the pulmonary arteries down to and including the subsegmental branches. But this sophisticated machine has also created new problems for clinicians who must care for patients who have what we now variously call incidental, asymptomatic, or unsuspected pulmonary thromboemboli—emboli that are clinically silent and detected unexpectedly. At this stage of our knowledge, we can say with certainty that these thromboemboli are common in all parts of the pulmonary arterial tree, are most often found in patients with cancer, carry a poor prognosis for patients with cancer, and are frequently missed during the initial CT reading. Their natural history and optimal management await definitive studies.