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3D-FT thin sections MRI of prolactin-secreting pituitary microadenomas
N Girard1, T Brue, V Chabert-Orsini
1Hôpital Nord, Marseille, France.
Abstract:
We studied 76 patients with endocrinological features of prolactin-secreting microadenoma by MRI, using three dimensional (3D) gradient echo acquisition (FLASH) sequences. MRI revealed a focal signal abnormality in the pituitary in all 37 patients who had not previously taken bromocriptine. However, focal abnormality was shown in only half the patients had been on dopamine agonist therapy; the MRI findings in these 39 patients were not affected by the duration and dosage bromocriptine, nor by the time elapsed since its discontinuation. The microadenoma gave spontaneous high signal on the unenhanced T1-weighted images in 8 cases; it was not seen on unenhanced images in 25 cases. It appeared as low signal within the enhancing gland in 51 cases but enhanced in 7 cases. The 3D technique gives thin (1 mm) slices and therefore facilitates detection of small focal abnormalities in the pituitary gland (2 x 2 mm). In the 19 previously treated patients in whom MRI did not demonstrate a focal abnormality, it showed localised atrophy of the gland in 3, a large, round gland with homogeneous signal in 1, and a heterogeneous appearance in 11; it was normal in 4 cases.
Insights
Magnetic Resonance Imaging (MRI) effectively detects pituitary microadenomas in patients not on bromocriptine. However, MRI findings are less reliable in patients undergoing dopamine agonist therapy for prolactin-secreting tumors.
Area of Science:
- Endocrinology
- Radiology
- Neuroimaging
Background:
- Prolactin-secreting microadenomas are common pituitary tumors.
- Dopamine agonist therapy, like bromocriptine, is a standard treatment.
- Accurate detection of microadenomas is crucial for diagnosis and monitoring.
Purpose of the Study:
- To evaluate the efficacy of three-dimensional (3D) gradient echo acquisition (FLASH) MRI sequences in detecting prolactin-secreting microadenomas.
- To assess the impact of bromocriptine therapy on MRI visualization of microadenomas.
Main Methods:
- Seventy-six patients with suspected prolactin-secreting microadenoma were studied using MRI.
- Three-dimensional (3D) gradient echo acquisition (FLASH) sequences were employed.
- Patients were categorized based on prior bromocriptine treatment status.
Main Results:
- MRI revealed focal abnormalities in all 37 patients not previously treated with bromocriptine.
- Only half of the 39 patients on dopamine agonist therapy showed focal abnormalities on MRI.
- MRI findings in treated patients were unaffected by bromocriptine dosage, duration, or discontinuation time.
- The 3D FLASH technique, with 1 mm slices, improved detection of small lesions (2 x 2 mm).
- In previously treated patients with no focal abnormality on MRI, other findings included localized atrophy (3), large round gland (1), heterogeneous appearance (11), or normal gland (4).
Conclusions:
- Three-dimensional (3D) MRI is highly sensitive for detecting pituitary microadenomas in untreated patients.
- Dopamine agonist therapy can significantly reduce MRI visibility of microadenomas.
- Further investigation is needed to understand the implications of these findings for treatment monitoring in patients on bromocriptine.