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A potential Adjunctive Role of 7T MRI and Amino-Acid PET in Localizing MRI-Occult Functional Pituitary Microadenomas:

Neetu Soni1, Manish Ora2, Yu Cai2

  • 1From the Department of Radiology (N.S., Y.C., V.G., P.V., J.V.M., S.J.S.S., E.H.M.), Nuclear Medicine (M.J., C.R.G., E.E.P.), DIVISION CHAIR-ENDO/METAB Department of Internal Medicine (S.L.S.), Mayo Clinic, Jacksonville, FL, USA; Department of Nuclear Medicine (M.O.), Sanjay Gandhi Post Graduate Institute of Medical Science, Lucknow, India; Department of Radiology (Y.C.), Zhongda Hospital, Nurturing Center of Jiangsu Province for State Laboratory of AI Imaging & Interventional Radiology, School of Medicine, Southeast University, 87 Dingjiaqiao Rd, Gulou District, Nanjing 210009, China; Department of Radiology (I.T.M., B.J.B., G.B.), Mayo Clinic, Rochester, USA; Professor at The University of Texas MD Anderson Cancer Center (A.A.) and Department of Radiology & Nuclear Medicine (S.E.M.V.V.Z.), Erasmus MC - University Medical Centre Rotterdam, Rotterdam, the Netherlands; Brain Tumour Centre, Erasmus MC Cancer Institute, Rotterdam, the Netherlands; Medical Delta, Delft, the Netherlands. Soni.Neetu@mayo.edu.

AJNR. American Journal of Neuroradiology
|June 4, 2026
PubMed
Abstract

Insights

Ultra-high-field 7T MRI and amino-acid PET show promise for detecting small, MRI-occult functional pituitary adenomas. Further research is needed to establish standardized protocols and assess cost-effectiveness for clinical use.

Area of Science:

  • Medical Imaging
  • Nuclear Medicine
  • Endocrinology

Background:

  • Functional pituitary adenomas (FPAs) smaller than 10 mm are often "MRI-occult" on standard MRI, posing diagnostic challenges.
  • This leads to repeated investigations and suboptimal patient outcomes.
  • Detecting these small adenomas is crucial for timely diagnosis and treatment.

Purpose of the Study:

  • To review the clinical utility and limitations of 7T MRI and amino-acid Positron Emission Tomography (AA-PET) for detecting "MRI-occult" FPAs.
  • To evaluate advanced imaging techniques for improved FPA localization.
  • To assess the current evidence for these emerging technologies.

Main Methods:

  • A systematic literature search was conducted across Medline, Embase, and Web of Science up to August 2025.
  • Studies evaluating 7T MRI and AA-PET (using tracers like L-[methyl-11C]methionine or O-(2-[18F]fluoroethyl)-L-tyrosine) for MRI-occult PAs were included.
  • Eighteen studies met the inclusion criteria, covering 7T MRI, MET-PET, FET-PET, and hybrid approaches.

Main Results:

  • 7T MRI demonstrates superior spatial resolution, signal-to-noise ratio, and tissue contrast compared to lower field strengths.
  • AA-PET offers high tumor-to-background contrast, aiding in the localization of "MRI-occult" FPAs.
  • Both techniques show potential for improved detection rates.

Conclusions:

  • Ultra-high-field 7T MRI and AA-PET are promising complementary imaging modalities for "MRI-occult" FPAs.
  • Current evidence is limited by small cohort sizes, heterogeneous protocols, cost, and accessibility.
  • Prospective multicenter studies and cost-effectiveness analyses are needed for clinical adoption.

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