From the Guidelines
A dedicated pituitary MRI with pre-contrast (T1 and T2) and post-contrast-enhanced (T1) thin-sliced sequences is recommended for evaluating high prolactin levels. This recommendation is based on the most recent consensus guideline for the diagnosis and management of pituitary adenomas, which suggests that this imaging protocol can provide increased sensitivity for adenoma detection 1. The use of a 3-Tesla MRI may also be considered for surgical planning or intra-operative MRI, as it can enhance anatomical definition and potentially improve completeness of resection without altering complication rates 1.
Key features of the recommended MRI protocol include:
- Pre-contrast T1 and T2 sequences to evaluate the pituitary gland and surrounding structures
- Post-contrast-enhanced T1 sequences to detect pituitary adenomas and distinguish between normal pituitary tissue and tumors
- Thin-slice (1-2mm) imaging protocols to detect small microadenomas
- Consideration of volumetric (gradient recalled echo) acquisition after contrast to improve sensitivity for adenoma detection
It is essential to note that the MRI should be reported by a neuroradiologist, and the use of macrocyclic or newer linear gadolinium-containing contrast agents in weight-adapted doses is recommended, especially in pediatric patients 1. Additionally, unenhanced T1-weighted and T2-weighted MRI sequences should be considered during follow-up, especially if good quality enhanced images have been obtained at diagnosis 1.
From the Research
MRI for High Prolactin Levels
To evaluate high prolactin levels, the following types of MRI are recommended:
- MRI with gadolinium is more sensitive and specific than CT scanning in detecting all types of pituitary tumors and is the study of choice 2
- T1-weighted spin-echo sequences, with coronal and sagittal images before and after intravenous gadolinium, can be used to investigate pituitary microadenomas 3
- Pituitary magnetic resonance imaging (MRI) should be obtained to identify pituitary tumors in all patients with persistently elevated PRL levels 4
When to Perform MRI
MRI should be performed in the following situations:
- In patients with prolactin levels more than 100 ng/ml 3
- In patients on oestrogen therapy with slightly elevated prolactin levels 3
- In cases where there is no clear etiology of hyperprolactinemia 2
- When clinical symptoms and/or a pituitary mass suggest the possibility of acromegaly 2
Important Considerations
- The presence of macroprolactinaemia does not exclude the possibility of a pituitary adenoma and consequently may not prevent pituitary imaging studies 5
- Patient samples showing hyperprolactinaemia should be first tested for macroprolactin, before the patient is submitted to imaging studies 5
- Imaging studies should be ordered in patients with macroprolactinaemia when indicated by clinically relevant features 5