CT and MR imaging evaluation of skull base2type pituitary adenoma<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

江波　孟悛非　陈应明　马玲

JIANG Bo, MENG Quan-fei, CHEN Ying-ming, MA Ling.

Department of Radiology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou 510080, China

Abstract

Objective：To probe the imaging diagnostic characteristics of skull base-type pituitary adenoma(SBPA).

Methods：CT, conventional MRI, dynamic MRI, and pathological data of 16 patients with SBPA were analyzed. The manifestations of both CT and conventional MRI, the dynamic time-signal curve, time of peak enhancement, and average enhancement rate were compared between SBPA in the 16 patients and chordoma of the skul. base (CSB) in another 9 patients.

Results：The CT appearances of both tumors were quite similar, offering no differential value. Both tumors were slightly hypointense on T₁ weighted images, but SBPA was mildly hyperintense and CSB was markedly hyperintense on T₂ weighted images. The T₂ weighted signal intensity between both tumors differed significantly (P < 0.001). Scattered hyperintense bubbles within the mildly hyperintense　tumoral background were noted on T₂ weighted images in SBPA, and T₂ weighted signal of the bubbles was much more hyperintense than that of the tumoral background ( P < 0.001) . The enlarged gland lumen of pituitary adenoma constituted the pathological base of the bubbles. The biphasic dynamic time-signal intensity curve was noted in SBPA, which composed of rapid enhancement phase and fast subsidence phase. While in CSB, the enhancement occurred within the 5 minutes immediately after the contrast injection. The time of peak enhancement and average enhancement rate between SBPA and CSB were statistically different, which were (60 ±10) s, (600±50) / min for SBPA, respectively, and > 5 min, (40 ±5) / min for CSB, respectively (P < 0.01, P < 0.001,respectively).

Conclusion：CT is of limited value in the diagnosis and differential diagnosis of SBPA. The pattern of hyperintense bubbles scattered within the mildly hyperintense tumoral background on T₂  weighted images is the characteristic MR finding of SBPA and is of defining value in the diagnosis of the tumor. Dynamic contrast-enhanced MRI possesses great differential diagnostic value between SBPA and CSB.

Key words：Pituitary adenoma； Skull base； Tomography, X-ray computed；Magnetic resonance Imaging

垂体大腺瘤的典型表现为肿瘤发生于鞍内,经鞍隔向鞍上发展,形成鞍内、鞍上的软组织肿块,CT、MRI 诊断不难^[1,2] 。但对于向鞍上发展轻微而向下发展、颅底骨质破坏明显的垂体大腺瘤,CT、MRI 诊断非常困难, 常常误诊为颅底骨源性肿瘤^[3,4] 。为有别于典型的垂体大腺瘤,笔者称此型垂体瘤为颅底型垂体瘤,有关这方面的CT、MRI 诊断研究国外少见报道,国内笔者尚未见报道。笔者旨在通过分析颅底型垂体瘤的CT、常规MRI、动态增强MRI 表现和肿瘤组织病理学资料,探讨其影像诊断特征。