For the first time,
researchers have confirmed an association between the use of common
Gadolinium-based contrast media (Gd-CM) and abnormalities on brain MRI,
according to a new study published online in the journal Radiology. The new
study raises the possibility that a toxic component of the contrast agent may
remain in the body long after administration. Gd-CM is considered safe in
patients with normal kidney function. However, recently, clinicians in Japan
noticed that patients with a history of multiple administrations of Gd-CM
showed areas of high intensity, or hyperintensity, on MRI in two brain regions:
the dentate nucleus (DN) and globus pallidus (GP). The precise clinical
ramifications of hyperintensity are not known, but hyperintensity in the DN has
been associated with multiple sclerosis, while hyperintensity of the GP is
linked with hepatic dysfunction and several diseases. To learn more, the
researchers compared unenhanced T1-weighted MR images (T1WI) of 19 patients who
had undergone six or more contrast-enhanced brain scans with 16 patients who
had received six or fewer unenhanced scans.
The hyperintensity of both
the DN and the GP correlated with the number of Gd-CM administrations.
“Hyperintensity in the DN and GP on unenhanced MRI may be a consequence of the
number of previous Gd-CM administrations,” said lead author Dr T Kanda from
Teikyo University School of Medicine in Tokyo and the Hyogo Cancer Center in
Akashi, Japan. “Because gadolinium has a high signal intensity in the body, our
data may suggest that the toxic gadolinium component remains in the body even
in patients with normal renal function.” Dr. Kanda noted that because patients
with multiple sclerosis tend to undergo numerous contrast-enhanced brain MRI
scans, the hyperintensity of the DN seen in these patients may have more to do
with the large cumulative gadolinium dose than the disease itself.
The mechanisms by which
Gd-CM administration causes hyperintensity of the DN and GP remain unclear, Dr.
Kanda said. Previous studies on animals and humans have shown that the ion can
be retained in bone and tissue for several days or longer after administration.
“The hyperintensity of DN and GP on unenhanced T1WI may be due to gadolinium
deposition in the brain independent of renal function, and the deposition may
remain in the brain for a long time,” Dr. Kanda suggested.
Dr Kanda emphasized that
there is currently no proof that gadolinium is responsible for hyperintensity
on brain MRI. Further research based on autopsy specimens and animal
experiments will be needed to clarify the relationship and determine if the
patients with MRI hyperintensity in their brains have symptoms.
There are two types of
Gd-CM, linear and macrocyclic, with distinct chemical compositions. Since the
patients in the study received only the linear type, additional research is
needed to see if the macrocyclic type can prevent MRI hyperintensity.
http://tinyurl.com/Kanda-et-al-paper
MR images in 45-year-old woman with glioblastoma treated with surgery, chemotherapy, and radiation therapy. (Top left) Unenhanced T1-weighted image shows high-signal-intensity globus pallidus. Standard ROIs were placed around globus pallidus and thalamus. (Top right) Fast spin-echo T2-weighted image at same level as a. (Bottom left) Unenhanced T1-weighted image shows high-signal-intensity dentate nucleus. Standard ROIs were placed around dentate nucleus and pons. ( Bottom Right) Fast spin-echo T2-weighted image at same level as Bottom left