Misinterpretation of I-131 scintigraphy because of diaphragmatic hernia

Hiatal hernia in iodine-131 scintigraphy: a potential cause of false-positive midline thoracic uptake

There are occasional reports of a hiatal hernia demonstrating thoracic uptake on I-131 scintigraphy. This is a cause of a potential false-positive appearance mimicking a pulmonary or mediastinal metastasis. Hiatal hernia is 1 of a number of causes of false-positive I-131 whole-body scans. Although previous case reports have demonstrated uptake to lie to the left of the midline, this case is slightly unusual in view of the midline appearance of the uptake. Although this appearance could be seen with mediastinal, pulmonary, or prevertebral metastases, hiatal hernia should be considered in the differential diagnosis of uptake in the thoracic midline on I-131 scintigraphy.

Artifacts, anatomical and physiological variants, and unrelated diseases that might cause false-positive whole-body 131-I scans in patients with thyroid cancer

The whole body 131-I scan remains an important component in the postoperative treatment of patients with well-differentiated thyroid cancer. Because normal thyroid tissue remnants and residual or metastatic foci of well-differentiated thyroid cancer have the unique ability to concentrate, organify, and store 131-I, the whole body scan provides a depiction of those tissues that can be ablated with therapeutic doses of 131-I. Over time, it has become obvious that the whole body scan may also reveal foci of 131-i uptake owing to a wide variety of other causes. We provide a detailed pathophysiological classification of the artifacts, anatomic and physiological variants, and nonthyroidal diseases that may give rise to false-positive whole body scans in postoperative patients with thyroid cancer. These include ectopic foci of normal thyroid tissue; nonthyroidal physiological sites (eg, choroid plexus, salivary glands, gastric mucosa, urinary tract); contamination by physiological sections; ectopic gastric mucosa; other gastrointestinal abnormalities; urinary tract abnormalities; mammary abnormalities; serous cavities and cysts; inflammation and infection; nonthyroidal neoplasms; and currently unexplained causes. This article also provides a detailed review of the widely scattered English language literature in which these phenomena were originally described.