Contrast Agent May Be Unnecessary in MRIs Checking Pediatric Growth

Gadolinium contrast is likely not necessary to evaluate patients with short stature for growth hormone deficiency, according to a new study, particularly when newer high-resolution sequences are leveraged.

Children with short stature are often referred for pediatric endocrinology evaluation, including radiological assessment with brain and pituitary MRI. About 1% to 2% of children with short stature have growth hormone deficiency.

Writing in the journal Hormone Research in Paediatrics, corresponding author Abdullah Almaghraby, MD, of the Anne and Robert H. Lurie Children’s Hospital of Chicago, and colleagues, explained that such MRI images are typically obtained using gadolinium-based contrast agents (GBCAs), which can be helpful in identifying small lesions like pituitary microadenomas.

Yet, Almaghraby and colleagues noted that it is not necessarily critical to find pituitary microadenomas, since they are usually not the cause of growth hormone deficiency, and their presence does not rule out treatment with growth hormones. Furthermore, GBCAs are costly and can lead to rare side effects, such as nephrogenic systemic fibrosis.

“Given the concerns for potential health risks associated with GBCAs, the fact that pituitary microadenomas do not appear to be associated with GHD, and the ability of non-contrast brain MRI images in detecting primary brain tumors, the necessity of using contrast material when obtaining brain and pituitary MRI in cases of short stature and/or isolated GHD should be reassessed,” the investigators wrote.

To accomplish that reassessment, the investigators conducted a retrospective review of healthy patients with short stature with and without growth hormone deficiency who underwent brain and pituitary MRI with and without the use of contrast agents.

A total of 318 patients met the inclusion criteria, about one-third of whom were females (101 patients, 32%). Among the 227 patients who underwent growth hormone stimulation testing, 28 patients (12.3%) were found to have normal growth hormone responses, and 62 (27.3%) were found to have severe growth hormone deficiency.

When comparing MRI results with and without the use of GBCAs, the investigators found a high degree of similarity.

“We found perfect agreement in detecting abnormal posterior pituitary bright spot and substantial agreement in detecting pars intermedia cysts and posterior superior sellar cysts,” they wrote.

There was only moderate agreement in detecting infundibular abnormalities. However, there was near perfect agreement in detecting incidental intracranial cysts including pineal gland cysts, arachnoid cysts, temporal lobe cysts and thalamic cysts, they said.

After identifying the lack of perfect agreement in detecting infundibular abnormalities, the investigators utilized a revised non-contrast MRI protocol using high-resolution 3-D images.

That technique proved successful in visualizing the infundibulum in all 15 patients evaluated.

“This suggests that imaging assessment of the infundibulum is not necessarily dependent on contrast enhancement, but rather on the spatial resolution of MRI, and we believe that non-contrast high resolution images can visualize the infundibulum and any associated abnormalities,” the authors said, though they added the caveat that the technique can be affected by metals, a problem when patients wear dental braces.

Almaghraby and colleagues said the non-contrast MRI technique does create an increased risk of overestimation of pituitary stalk interruption, but they said this can be overcome by using newer high-resolution sequences.

The patients in the study had a low incidence of sellar and suprasellar masses; the authors added that the identification of a mass may make it necessary to do repeat imaging with contrast. However, in general, they said their findings suggest the risks of using GBCAs for assessment of short stature in growth hormone deficiency may outweigh the benefits.

Reference

Almaghraby A, Jaju A, Ryan ME, Rychlik K, Habiby RL, Brickman WJ. Is gadolinium contrast necessary for pituitary mri in the evaluation of pediatric short stature and growth hormone deficiency? Horm Res Paediatr. Published online August 23, 2021. doi:10.1159/000519031