Pituitary Macroadenoma
author, Val M. Runge, MD
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Clinical History:
This 64-year-old man presented clinically with a complaint of vision loss over the last year. Ophthalmologic exam revealed a bitemporal hemianopsia and the patient was referred for MRI. A prolactin level was normal. The lesion was subsequently resected via an intranasal approach.
Diagnosis:
Pituitary macroadenoma
MR Technique:
Scans were acquired at 3 T on a Siemens Tim Trio using a 12-channel head coil. Coronal pre-contrast T1- and T2-weighted scans are displayed, in addition to a sagittal post-contrast (20 ml ProHance) T1-weighted scan. The slice thickness was 2 mm in each instance. Scan times were 3:36, 2:12, and 4:48 minutes:seconds, with an in-plane spatial resolution of 0.9x0.7, 0.7x0.6, and 0.9x0.7 mm2, respectively.
Imaging Findings:
A soft tissue mass fills and expands the sella, extending suprasellar in location to compress and splay the optic chiasm. The lesion has a dumbbell like appearance, constricted at the waist by the diaphragma sellae. On the sagittal post-contrast scan there is intermediate, near homogeneous, enhancement of the lesion. These findings are all characteristic for a large non-hormonal secreting macroadenoma. Important MR technique issues include the routine use of 2 mm thin section imaging (as opposed to 3 mm), made possible by imaging at 3 T. This improves anatomic depiction of the lesion, including in particular the thinning of the optic chiasm. The use of a short TE (2.6 msec in this instance) 2D spoiled gradient echo sequence (FLASH) at 3 T leads to consistent high image quality, with good gray-white matter contrast and no restrictions due to heat deposition (SAR), with an additional important factor being that the image is not degraded by vessel pulsation artifacts. Note the clear depiction of the superior sagittal sinus on the post-contrast scan, without detectable ghosting or other degradation due to motion artifacts.
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