Mahmutyazicioğlu Kamran, Ozdemir Hüseyin, Savranlar Ahmet, Sümer Murat, Atasoy Tuğrul, Unal Aysun, Gündoğdu Sadi
Zonguldak Karaelmas Universitesi Tip Fakültesi, Radyodiagnostik Anabilim Dali, Zonguldak, Turkey.
Tani Girisim Radyol. 2004 Sep;10(3):182-8.
DIR (double inversion recovery) is a sequence with the hybrid contrast of both FLAIR and STIR sequences, produced by the application of double inversion recovery pulse. It has been suggested that DIR provides high sensitivity to lesions with low T2 contrast. The purpose of this study was to test the hypothesis that DIR sequence is superior to conventional sequences in the identification of mesial temporal sclerosis and other temporal lobe lesions in patients with temporal lobe epilepsy.
Thirty-three subjects with a prediagnosis of temporal lobe epilepsy and ten healthy control subjects with no abnormality on magnetic resonance imaging studies have been studied with DIR, FLAIR and T2W sequences. Coronal images through temporal lobes and hippocampus were acquired. Qualitatively, overall sensitivity to the presence of lesions, hippocampal lesion detectability, temporal horn dilatation and artifacts were evaluated in temporal lobe epilepsy cases and quantitatively, hippocampal and white matter signal-to-noise ratio as well as hippocampus-white matter contrast-to-noise ratio were calculated in the healthy subjects. Subjective scores were graded on a scale of 3 or 4 points.
Signal-to-noise ratio scores were higher on T2W sequence, however contrast-to-noise ratio scores were higher on DIR sequence compared to the other two sequences. Imaging findings were compatible with mesial temporal sclerosis in seven patients, tumoral mass in two, and chronic infarct in four. DIR sequence was less sensitive to hippocampal atrophy than the other two sequences because of cerebrospinal fluid artifacts. Overall sensitivity to the presence of lesions and hippocampal lesion detectability scores, although similar among three sequences, were highest with DIR sequence. However, lesion sensitivity scores were highest for lesions compatible with mesial temporal sclerosis and for solid masses and lowest for cystic lesions on DIR sequence.
Despite the presence of artifacts, DIR is a sequence providing high sensitivity to mesial temporal sclerosis like lesions at hippocampus. DIR might be useful as an additional sequence when the other conventional sequences reveal a suspicious lesion with no accompanying hippocampal atrophy.
双反转恢复序列（DIR）是一种通过应用双反转恢复脉冲产生的具有液体衰减反转恢复序列（FLAIR）和短反转恢复序列（STIR）混合对比的序列。有人提出DIR对T2对比度低的病变具有高敏感性。本研究的目的是检验DIR序列在识别颞叶癫痫患者的内侧颞叶硬化和其他颞叶病变方面优于传统序列这一假设。
对33例预诊断为颞叶癫痫的受试者和10例磁共振成像检查无异常的健康对照受试者进行DIR、FLAIR和T2加权序列（T2W）检查。获取通过颞叶和海马的冠状位图像。在颞叶癫痫病例中，定性评估对病变存在的总体敏感性、海马病变的可检测性、颞角扩张和伪影，并在健康受试者中定量计算海马和白质的信噪比以及海马 - 白质对比噪声比。主观评分采用3分或4分制。
T2W序列的信噪比得分更高，但与其他两个序列相比，DIR序列的对比噪声比得分更高。影像学表现符合7例内侧颞叶硬化、2例肿瘤性肿块和4例慢性梗死。由于脑脊液伪影，DIR序列对海马萎缩的敏感性低于其他两个序列。尽管三个序列之间对病变存在的总体敏感性和海马病变可检测性评分相似，但DIR序列最高。然而，对于与内侧颞叶硬化相符的病变和实性肿块，DIR序列的病变敏感性评分最高，而对于囊性病变则最低。
尽管存在伪影，但DIR是一种对海马处类似内侧颞叶硬化的病变具有高敏感性的序列。当其他传统序列显示可疑病变且无伴随海马萎缩时，DIR可能作为一个补充序列有用。
