VALUE OF T1-RELAXATION AND T2-RELAXATION TIMES FROM ECHOPLANAR MR IMAGING IN THE CHARACTERIZATION OF FOCAL HEPATIC-LESIONS
VALUE OF T1-RELAXATION AND T2-RELAXATION TIMES FROM ECHOPLANAR MR IMAGING IN THE CHARACTERIZATION OF FOCAL HEPATIC-LESIONS
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DOI：
10.2214/ajr.160.5.8470568
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发表时间：
1993-05-01
影响因子：
5
通讯作者：
MUELLER, PR
中科院分区：
文献类型：
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作者：
GOLDBERG, MA;HAHN, PF;MUELLER, PR
目标。本研究的目的是根据图像获得的T1和T2弛豫时间来确定回波平面成像在肝脏局灶性病变定性中的价值。分析了46个已证实的肝脏病变：24个实性病变(21个转移瘤，3个原发性肝肿瘤)和22个非实性病变(11个血管瘤和11个囊性病变)。病灶平均大小(最大长度)为4.0(+/-3.2)cm，其中16个小于2.0 cm。使用商用的1.5-T ECHO平面配置的MR扫描仪获得层厚为10 mm的脂肪抑制、单次激发(TR本质上是无限的)轴位图像。46个病灶中28个获得了T1加权反转恢复图像(TE=25毫秒；TI=100、380、600或800毫秒)，45个获得了T2加权自旋回波图像(TE=25、50、100、75或150毫秒)。对于每一次采集(即每个不同的TI或TE)，整个肝脏在12秒或更短的一次屏气时间内成像。结果：实质性病变的平均T1为1004(+/-234)毫秒，血管瘤为1337(+/-216)毫秒，囊性病变为3143(+/-1392)毫秒。尽管实性和非实性病变的平均T1不同(p<；.004)，但重叠排除了T1作为判别性指标的使用。实质病变的平均T2时间为80(+/-18)毫秒，血管瘤为178(+/-40)毫秒，囊性病变为517(+/-429)毫秒。血管瘤的平均T2是迄今为止报道的最长的。以116毫秒的T2为界，对实性或非实性病变的分类准确率为100%，对良性或恶性病变的定性准确率为93%。结论：我们的研究表明，回声平面衍生的T2次(但不是T1次)对肝局灶性病变的定性是有用的。一个重要的用途可能是确定小于2.0厘米的小病变的特征。回波平面成像的主要优点是没有运动引起的体积平均和相位伪影，能够获得纯T2加权图像，并且使用多个数据点来计算松弛时间。
OBJECTIVE. The purpose of this study was to determine the value of echoplanar imaging in characterizing focal hepatic lesions on the basis of image-derived T1 and T2 relaxation times.SUBJECTS AND METHODS. Forty-six proven hepatic lesions were analyzed: 24 solid (21 metastases, three primary liver tumors) and 22 nonsolid (11 hemangiomas and 11 cysts). Mean lesion size (maximal length) was 4.0 (+/- 3.2) cm, and 16 of 46 lesions were less than 2.0 cm. A commercially available 1.5-T echoplanar-equipped MR scanner was used to obtain fat-suppressed, single-excitation (TR essentially infinite) axial images with a slice thickness of 10 mm. T1-weighted inversion recovery images (TE = 25 msec; TI = 100, 380, 600, or 800 msec) were acquired for 28 of 46 lesions, and T2-weighted spin-echo images (TE = 25, 50,100, 75 or 150 msec) were acquired for 45 of 46 lesions. For each acquisition (i.e., each different TI or TE), the entire liver was imaged in a single breath-hold of 12 sec or less.RESULTS. The mean T1 was 1004 (+/- 234) msec for solid lesions, 1337 (+/- 216) msec for hemangiomas, and 3143 (+/- 1392) msec for cysts. Although the mean T1 of solid and nonsolid lesions differed (p < .004), overlap precluded the use of T1 as a discriminatory index. Mean T2 times were 80 (+/- 18) msec for solid lesions, 178 (+/- 40) msec for hemangiomas, and 517 (+/- 429) msec for cysts. The mean T2 for hemangiomas is the longest reported to date. A T2 cutoff of 116 msec was 100% accurate for classifying lesions as solid or nonsolid and 93% accurate for characterizing them as benign or malignant.CONCLUSION. Our study suggests that echoplanar-derived T2 times (but not T1 times) are useful for characterizing focal hepatic lesions. An important use may be to characterize small lesions measuring less than 2.0 cm. The main advantages of echoplanar imaging are the absence of motion-induced volume averaging and phase artifacts, the ability to acquire purely T2-weighted images, and the use of multiple data points to calculate relaxation times.