The effect of gadolinium contrast media on radioiodine uptake by the thyroid gland.
OBJECTIVE
Patients with thyroid cancer may require detailed anatomic imaging before 131I therapy. Imaging by contrast-enhanced CT is contraindicated because it may result in saturation of tissues with iodine, decreasing the avidity of thyroid or thyroid cancer cells to subsequent radioiodine for extended intervals. Gadolinium-enhanced MRI offers an alternative to CT for detailed anatomic imaging. However, it is not known whether gadolinium contrast affects uptake of iodine by the thyroid gland since lanthanides affect ion transport in a variety of ways. The objective of this project was to determine whether the gadolinium MRI contrast injection alters thyroid uptake of radioiodine.


METHODS
Radioiodine uptake by the thyroid gland was measured at 6 h and 24 h after the oral administration of 100 microCi 123I-Na-I. Three to seven days later, a standard dose (20 mL) of Magnevist (gadolinium DTPA) was administered intravenously. Another capsule of 100 microCi 123I Na-I immediately was given orally, and 6-h and 24-h radioiodine uptake by the thyroid gland was again measured and compared to baseline values.


RESULTS
There was no statistically significant difference in uptake of radioiodine uptake by the thyroid gland between baseline values and those acquired immediately after the administration of Magnevist.


CONCLUSIONS
Contrast-enhanced MRI may be safely performed before contemplated determinations of thyroid uptake of radioiodine, 131I therapy for hyperthyroidism, and postsurgical 131I imaging and therapy for well-differentiated thyroid cancer.
Christensen
C R
CR
Salt Lake Regional Medical Center, Salt Lake City, Utah, USA.
Glowniak
J V
JV
Brown
P H
PH
Morton
K A
KA
D000328:Adult; D003287:Contrast Media; D019786:Gadolinium DTPA; D006801:Humans; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D013961:Thyroid Gland / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000378:metabolism
D003287:Contrast Media; D007457:Iodine Radioisotopes; D019786:Gadolinium DTPA