Tang Y, Yamashita Y, Namimoto T, Takahashi M
Department of Radiology, Kumamoto University School of Medicine, Honjo, Japan.
J Magn Reson Imaging. 1998 Mar-Apr;8(2):438-45. doi: 10.1002/jmri.1880080226.
The half-Fourier acquisition single-shot turbo-spin-echo (HASTE) sequence allows for heavily T2-weighted images, and the inversion recovery (IR)-HASTE sequence represents the T1 value of the tissue in a very short time. This study was undertaken to determine whether characterizing focal liver lesions can be made by combination with these very fast sequences. Seventy-four patients (33 cysts, 28 hemangiomas, and 33 malignant solid liver masses [15 metastatic tumors, 14 hepatocellular carcinomas, and 4 cholangiocarcinomas) underwent dynamic CT and breath-hold abdominal MRI using turbo-spin-echo (TSE), HASTE, and IR-HASTE sequences with variable T1 values on a 1.5-T MR unit. The imaging time for each slice was 2 seconds for HASTE imaging and 2 to 4 seconds for IR-HASTE imaging. Lesion detection and qualitative characterization were evaluated. Quantitative analysis was performed by measuring the contrast-to-noise ratios (CNRs) as well as visual analysis. The inversion time (TI) nulling values were also statistically analyzed. All cystic lesions were detected on both TSE and HASTE imagings. For solid lesions, TSE failed to detect one small solid lesion and HASTE sequence failed to detect three lesions. With HASTE sequences, all cysts and hemangiomas were markedly hyperintense in comparison with malignant solid masses. CNRs of hemangiomas or cysts were significantly higher than those of malignant solid masses (P < .01), and there was no overlap. The TI nulling value was 1,100+/-100 msec for hemangiomas, 1,900+/-110 msec for cysts, and 740+/-140 msec for malignant solid masses. There was no overlap between the TI nulling values of hemangiomas and cysts (P < .01). By combining the CNR from the HASTE sequence and the TI nulling value from the IR-HASTE sequence, complete discrimination among malignant solid masses, hemangiomas, and cysts of the liver could be made. Application of HASTE (representing T2 values) and IR-HASTE (representing T1 values) sequences provided a rapid and reliable imaging method for characterizing focal liver lesions without the use of contrast medium.
半傅里叶采集单次激发快速自旋回波（HASTE）序列可用于获取重度T2加权图像，而反转恢复（IR）-HASTE序列能在极短时间内显示组织的T1值。本研究旨在确定联合使用这些超快速序列能否对肝脏局灶性病变进行特征性诊断。74例患者（33个囊肿、28个血管瘤和33个肝脏恶性实性肿块[15个转移瘤、14个肝细胞癌和4个胆管癌]）在1.5T磁共振设备上采用快速自旋回波（TSE）、HASTE和具有不同T1值的IR-HASTE序列进行了动态CT及屏气腹部MRI检查。HASTE成像时每层的成像时间为2秒，IR-HASTE成像时为2至4秒。对病变的检测及定性特征进行了评估。通过测量对比噪声比（CNR）以及视觉分析进行定量分析。对反转时间（TI）的归零值也进行了统计学分析。所有囊性病变在TSE和HASTE成像上均能被检测到。对于实性病变，TSE未能检测到1个小实性病变，HASTE序列未能检测到3个病变。在HASTE序列上，与恶性实性肿块相比，所有囊肿和血管瘤均表现为明显高信号。血管瘤或囊肿的CNR显著高于恶性实性肿块（P<0.01），且无重叠。血管瘤的TI归零值为1100±100毫秒，囊肿为1900±110毫秒，恶性实性肿块为740±140毫秒。血管瘤和囊肿的TI归零值之间无重叠（P<0.01）。通过联合HASTE序列的CNR和IR-HASTE序列的TI归零值，可对肝脏恶性实性肿块、血管瘤和囊肿进行完全鉴别。应用HASTE（代表T2值）和IR-HASTE（代表T1值）序列为肝脏局灶性病变的特征性诊断提供了一种无需使用对比剂的快速且可靠的成像方法。
