• Takahiro Takahashi, Yukio Miki, Jun A Takahashi, Mitsunori Kanagaki, Akira Yamamoto, Yasutaka Fushimi, Tsutomu Okada, Tabassum Laz Haque, Nobuo Hashimoto, Junji Konishi, and Kaori Togashi.
• Department of Nuclear Medicine and Diagnostic Imaging, Graduate School of Medicine, Kyoto University, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto-shi, Kyoto 606-8507, Japan.
• Eur J Radiol. 2005 Jul 1; 55 (1): 84-91.

Background And PurposeIn patients with macroadenoma, posterior pituitary high signal (PPHS) on T1-weighted magnetic resonance (MR) imaging is sometimes observed in an ectopic location. The present study compared incidences of ectopic PPHS before and after macroadenoma surgery using MR imaging, including dynamic MR imaging to ascertain whether this ectopic change is irreversible.Materials And MethodsMR imaging was performed preoperatively in 111 cases of macroadenoma, and then repeated more than 1-year postoperatively in 47 patients. Enhancement of PPHS was assessed using dynamic MR imaging. Areas of enhanced hyperintensity were considered true PPHS, and the relationship between presence and location of true PPHS and adenoma volume was analyzed. Moreover, changes in the presence and location of true PPHS were ascertained among the patients who underwent postoperative follow-up MR imaging.ResultsPreoperatively, PPHS was seen only in the normal location in 29 patients (Group A: 26.1%). High signal was detected only in an ectopic location in 58 patients, and early enhancement of this ectopic high signal was confirmed by dynamic MR imaging in 56 patients (Group B: 50.5%). No PPHS was observed in 24 patients (Group C: 21.6%). Adenoma volume was significantly greater for Group B than for Group A (p<0.001). Among the Group B patients who underwent MR imaging postoperatively (n=31), the location of PPHS was not changed, except for two patients in whom PPHS was absent. Postoperatively, PPHS was not observed in the normal location in any patient in the Group B.ConclusionsGreater volume of adenoma is associated with a higher incidence of ectopic PPHS, and the ectopic change is irreversible.

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