动态增强MRI在垂体微腺瘤诊断中价值

Value of Dynamic Contrast-enhanced MRI in the Diagnosis of Pituitary Microadenoma

背景与目的:垂体微腺瘤是临床上常见的垂体疾病,诊断需靠临床表现、生化指标检查及影像学表现相结合。MRI是最具有诊断价值的方法之一。垂体局限性低密灶是诊断微腺瘤重要的直接征象。但就MRI而言,不同扫描方法诊断垂体微腺瘤的准确率差异较大(45%～100%)。本研究旨在探讨动态增强MRI在垂体微腺瘤诊断中价值。方法:对62例经临床表现、生化指标检查诊断为垂体微腺瘤的患者进行MRI平扫、Gd DTPA动态增强扫描及延迟的常规增强扫描并分析其MR信号特征。结果:平扫、动态增强和常规延迟增强扫描微腺瘤检出率分别为46.8%(29/62)、88.7%(55/62)和64.5%(40/62)。这3种不同的扫描方法对病灶的检出率有显著差异(P<0.01)。结论:动态增强扫描、常规延迟增强扫描可提高病灶的检出率,其中以动态增强扫描病灶检出率最为显著。动态增强扫描可作为MR诊断垂体微腺瘤首选强化方法。

BACKGROUND & OBJECTIVE: Pituitary microadenoma is the most common pituitary disorder. The diagnosis requires the analysis of clinical features, biochemical study and images investigation. MRI is the best imaging technique for diagnosing pituitary microadenoma. There are different MRI imaging techniques including plain MRI scan, conventional Gadolinium (Gd)-DTPA contrast-enhanced MRI (conventional enhanced MRI), and dynamic Gadolinium (Gd)-DTPA contrast-enhanced MRI (dynamic MRI). The sensitivity in detecting pituitary microadenoma varies between 45% and 100% when using different MRI techniques. Low attenuation on plain Tl-weighted MRI image is a sign of microadenoma. Normal pituitary gland and pituitary adenoma both enhanced on Gd-DTPA but at a different time frame. On conventional enhanced MRI, the pituitary microadenoma appears less enhanced than the normal pituitary gland. In the dynamic MRI, serial images are taken over a short period of time after injection of Gd-DTPA. Pituitary microadenoma enhance later than normal pituitary gland. In this paper, we evaluated the value of dynamic MRI in the diagnosis of pituitary microadenomas. METHODS: Sixty-two cases with pituitary microadenomas confirmed by clinical manifestation and biochemical analysis were studied by using plain MRI scan, dynamic MRI and conventional enhanced MRI. RESULTS: The sensitivity in detecting pituitary microadenoma using plain MRI scan, dynamic MRI and conventional enhanced MRI were 46. 8% (29/62), 88. 7% (55/62) and 64. 5% (40/62), respectively. The differences among the three scanning methods were statistically significant (P < 0. 01). CONCLUSION: Both the dynamic MRI and conventional enhanced MRI are superior to plain MRI scan in detecting pituitary microadenoma. The dynamic MRI is the most sensitive one, and should be considered as the primary imaging modality in diagnosing pituitary microadenoma.