Mariappan, Yogesh Kannan

BACKGROUND Thyroid-stimulating hormone (TSH)–secreting pituitary adenomas (TSHomas) are rare lesions that result in secondary hyperthyroidism. MR elastography (MRE) is an emerging imaging modality capable of assessing the mechanical properties of tissues, offering valuable insights into tumor consistency for improved preoperative planning and resection. OBSERVATIONS A 16-year-old female diagnosed with a giant TSHoma underwent endoscopic transnasal transsphenoidal excision. The mechanical properties of TSHoma were assessed using preoperative MRE and in vitro nanoindentation on excised specimen. Collagen content was also evaluated. Based on its appearance on MRE, a neuroradiologist predicted the tumor would be soft, and it was found to be soft during the surgery. Interestingly, the in vitro shear storage and loss moduli closely match the in vivo findings. Additionally, the tumor tissue has up to 20% collagen content in intratumoral areas. LESSONS MRE is a reliable and clinically valuable tool for preoperative evaluation of tumor consistency in rare TSHomas. The strong concordance between MRE findings, intraoperative texture, and in vitro mechanical measurements underscores the potential of MRE to guide surgical planning, reduce operative complexity, and improve clinical outcomes, especially in uncommon and challenging cases. https://thejns.org/doi/10.3171/CASE25402

Magnetic resonance elastography (MRE) is a MR imaging method capable of spatially resolving the intrinsic mechanical properties of normal lung parenchyma. We tested the hypothesis that the mechanical properties of edematous lung exhibit local properties similar to those of a fluid-filled lung at transpulmonary pressures (Ptp) up to 25 cm H2O. Pulmonary edema was induced in anesthetized female adult Sprague-Dawley rats by mechanical ventilation to a pressure of 40 cm H2O for ∼30 min. Prior to imaging the wet weight of each ex vivo lung set was measured. MRE, high-resolution T1-weighted spin echo and T2* gradient echo data were acquired at each Ptpfor both normal and injured ex vivo lungs. At Ptps of 6 cm H2O and greater, the shear stiffness of normal lungs was greater than injured lungs ( P ≤ 0.0003). For Ptps up to 12 cm H2O, shear stiffness was equal to 1.00, 1.07, 1.16, and 1.26 kPa for the injured and 1.31, 1.89, 2.41, and 2.93 kPa for normal lungs at 3, 6, 9, and 12 cm H2O, respectively. For injured lungs MRE magnitude signal and shear stiffness within regions of differing degrees of alveolar flooding were calculated as a function of Ptp. Differences in shear stiffness were statistically significant between groups ( P < 0.001) with regions of lower magnitude signal being stiffer than those of higher signal. These data demonstrate that when the alveolar space filling material is fluid, MRE-derived parenchymal shear stiffness of the lung decreases, and the lung becomes inherently softer compared with normal lung.