New Scanner may diagnose MRI-negative pituitary adenomas

Cushing’s disease comprises a specific set of symptoms, including weight gain, skin bruising, hair loss and in women, irregular or missed periods. Over time, patients typically develop high blood pressure, diabetes, and frequent infections.It is caused by adrenocorticotrophic hormone (ACTH)–secreting pituitary adenomas, which are often difficult to identify on standard 1.5-T or 3-T MRI, including dynamic contrast imaging. At present Inferior petrosal and cavernous sinus sampling remains the gold standard for MRI-negative Cushing’s disease.Dr.Meng Law & associates have found that an ultra-high field 7Tesla Magnetic Resonance Imaging scanner may be beneficial in identifying pituitary microadenoma location in cases of standard 1.5-T and 3-T MRI-negative Cushing’s disease.They have published their findings through a case reported in Journal of Neurosurgery.

The authors report on a 27-year-old woman with Cushing’s disease in whom the results of standard 1.5-T and 3-T MRI, including 1.5-T dynamic contrast imaging, were negative. Inferior petrosal sinus sampling showed a high central-to-peripheral ACTH ratio (148:1) as well as a right-to-left ACTH gradient (19:1), suggesting a right-sided pituitary microadenoma. The patient underwent 7-T MRI, which showed evidence of a right-sided pituitary lesion with focal hypoenhancement not visualized on 1.5-T or 3-T MRI. The patient underwent an endoscopic endonasal transsphenoidal operation, with resection of a right-sided pituitary mass. Postoperatively, she developed clinical symptoms suggestive of adrenal insufficiency and a nadir cortisol level of 1.6 μg/dl on postoperative day 3, and hydrocortisone therapy was initiated. Permanent histopathology specimens showed Crooke’s hyaline change and ACTH-positive cells suggestive of an adenoma.

The authors have concluded that MRI at 7 T may be beneficial in identifying pituitary microadenoma location in cases of standard 1.5-T and 3-T MRI-negative Cushing’s disease. In the future, 7-T MRI may preempt inferior petrosal sinus sampling and help in cases of standard and dynamic contrast 1.5-T and 3-T MRI-negative Cushing’s disease.“This is the first time a 7T has been used to scan a Cushing’s patient in the U.S., and we’re very excited about the results,” Law said. “The new technology has the potential to replace the standard method of diagnosis, which is much more invasive.”The case provides an early example of how the institute’s new high-resolution scanner can help ease patient suffering and even save lives.