Brachytherapy seed migration to the lung
Brachytherapy seed migration to the lung is a known complication of radioactive seed therapy. These seeds are used for localized treatment of malignancies, most commonly prostate cancer.
Regarding staging, nearly 79% of the cases are localized, 12% are regional and 5% present with distant disease . Currently, there are several management options for prostate cancer, including active surveillance, radical prostatectomy and radiation therapy (external beam and brachytherapy).
The most frequent site of seed migration is the lung. Sugawara et al. reported 0.36% of implanted seed migration to the chest in 20% of patient population .
The proposed migration route is via the periprostatic veins to the iliac veins, right heart and then the lungs. Migration to the heart, coronary arteries, liver, bladder, renal arteries and testicular vein has also been reported .
The majority of the cases are asymptomatic and incidentally found.
Nonetheless, several reports describe symptomatic presentation with hematuria, flank and back pain, chest pain, acute myocardial infarction, acute cardiac dysrhythmia and testicular swelling .
Usually, only one or two seeds migrate, and therefore it has no significant effect on postimplant dosimetry .
On CT the migrated seed appears as a linear hyperdense structure, with extreme beam and streak artifacts relative to their small size.
Treatment and prognosis
The latest consensus guidelines for transrectal ultrasound-guided permanent prostate brachytherapy by the American Brachytherapy Society no longer recommends the use of imaging methods for the detection of seed migration. The American College of Radiology appropriateness criteria follows the same recommendations as the American Brachytherapy Society .