Multiphasic Dynamic MR Imaging of Focal Nodular Hyperplasia

肝臟局部結節增生之多相動態磁振造影

羅中平(Chung-Ping Lo) ； 余之泳(Chih-Yung Yu) ； 林昌琦(Chang-Chyi Lin) ； 劉昌憲(Chang-Hsien Liu) ； 徐榮源(Rong-Yuan Shyu) ； 劉耀基(Yao-Chi Liu) ； 陳震宇(Cheng-Yu Chen)

《中華放射線醫學雜誌》 28卷5期 (2003/10) Pp. 277-284

摘要

本研究之目的為評估肝臟局部結節增生於多相動態磁振造影上之表徵。我們回顧分析過去8年間3個經由手術，4個經由切片，以及9個經由臨床追蹤，而證實為肝臟局部結節增生之15位病患的16個病灶。其中10位病患為男性，5位為女性，年齡層分佈為21之62歲，平均年齡為33.1歲。我們使用1.5-Tesla磁振造影掃描儀及phased-array體表線圈。先取得T1-wighted FLASH和T2-weighted HASTE＆FSE影像後，再經由靜脈注射每公斤體重0.1mmole劑量的Gd-DTPA，以取得fat-suppressed T1-weighted FLASH動態影像。動脈相時間設定在第30秒，門靜脈相設定在第70秒，延遲影像則取第3分鐘，6分鐘及10分鐘。
大部分的病灶在T1-weighted FLASH 影像中呈現出些微的低訊號（n=10,63%）
，而在T2-weighted HASTE＆FSE影像上呈現出些微的高訊號（n=11,69%）；動態影像上呈現出均勻高血管性的動脈相 （n=16,100%）；到了門靜脈相和延遲影像則呈現出等訊號（n=8,50%）或略高於肝臟實質之訊號（n=8,50%）。有12個病灶在影像上發現有中心疤痕組織；中心疤痕組織於T1-weighted FLASH影像上呈現出低訊號（n=9,75%），在T2-weighted HSTEM＆FSE影像上呈現高訊號（n=9,75%），而動態影像上於動脈相呈現出低訊號（n=12,100%），但每一病灶均會呈現延遲顯影之高訊號，分別在門靜脈相（n=2,17%），延遲3分鐘影像（n=4,33%），6分鐘影像（n=3,25%），及10分鐘影像（n=3,25%）。中心疤痕組織有7例小於5mm，4例介於5mm至1cm，1例大於2cm。僅有1例外包覆有一層纖維膜。
磁振造影已成為廣泛應用於診斷肝臟局部結節增生的良好工具，在我們的研究中發現，使用顯影劑之多相動態磁振造影被認為優於未打顯影劑之影像，而6分鐘以上之延遲影像是顯示中心疤痕組織的必要條件。典型的肝臟局部結節增生影像的特徵室均勻的（通常為單一個）腫塊於T1-weighted影像上呈現出與肝臟實質相等或略低的訊號，而於T2-weighted 影像上呈現相等或略高的訊號；而中心疤痕組織相對於腫瘤在T1-weighted影像上呈現更低的訊號，但T2-weighted影像上則呈現高訊號。腫瘤於多相動態影像之動脈像呈現出增強顯影，而中心疤痕組織則於延遲影像呈現出增強顯影。

關鍵字

肝臟局部結節增生 ； 多相動態磁振造影

並列摘要

The purpose of this study is to evaluate the plain and multiphasic dynamic Gd-enhanced MR imaging features of hepatic focal nodular hyperplasia (FNH) with breath-hold MR sequences.
Retrospectively, sixteen lesions of FNH in fifteen patients (ten male and five female) were reviewed. Among the sixteen lesions, three were proved by surgery, four by percutaneous biopsy, and the other nine by clinical follow-up. Patient's age ranged from 21 to 62 years old (mean 33.1). MR examinations were performed with a 1.5-T superconducting whole body imager and phased-array body coil. All patients in pre-contrast scan were imaged with breath-hold T1-weighted fast low angle shot (FLASH) , T2-weighted half-Fourier acquisition single-shot turbo-spin echo (HASTE) and T2-weighted fast spine echo (FSE) sequences. Multiphasic dynamic gadolinium (Gd)-enhanced MR images were obtained at 30 seconds, 70 seconds 3 minutes, 6 minutes and 10 minutes following a bolus of intravenous injection of 0.1 mmole/kg Gd-DTPA with fat-saturation breath-hold T1-weighted FLASH sequence.
FNH could be detected on T1-weighted FLASH images as hypointense lesions (n=10,63%) and T2-weighted FSE or HASTE images as hperintense lesions (n=11,69%) Gd-enhanced dynamic MR imaging demonstrated homogeneous and complete enhancement (except central scar if present) ib arterual-phase imaging (n=16,100%) . Portal-venous-phase and delayed-phase imaging showed isointense (n=8,50%) or slightly hyperintense (n=8,50%). Central scar could be identified in twelve lesions and showed to be hypointense on T1-weighted (n=9,75%) and hyperintense on T2-weighted images (n=9,75%). In dynamic study, central scar scar could be depicted in portal-venous-phase images (n=2,17%) or a series of delayed scans:3 minutes (n=4,33%), 6 minutes (n=3,25%),and 10 minutes (n=3,25%). Size of the central scar in seven lesions was smaller than 5 mm (58%), four was 5mm to 1cm (33%), and one was 2 cm in diameter (8%). Only one particular lesion demonstrated capsule formation.
Breath-holding plain and dynamic multiphasic MR imaging have been used broadly in the diagnosis of FNH. In the present study, both arterial-and delayed-phase images with Gd-enhanced T1-weighted sequences were thought to be superior to plain images in lesion detection. We also demonstrated that delayed scan longer than 6 minutes is essential to depict the tiny central scar. Typical MR imaging features of FNH included homogeneous solid mass with iso- or slightly hypointense on T1-weighted, iso- or slightly hyperintense on T2-weighted images as compared to surrounding normal liver parenchyma. Central scar presented as markedly hypointense on T1-weighted and iso- or hyperintense on T2-weighted images as compared to tumor. Dynamic study of main tumor demonstrated strong enhancement during arterial-phase imaging but central scar depicted strong enhancement during delayed-phase imaging.

並列關鍵字

Focal nodular hyperplasia ； liver ； multiphasic dynamic MRI