From the Department of Cancer Imaging (A.L., S.L.S., L.C.), Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
Sir Peter MacCallum Department of Oncology (A.L., S.L.S., G.A.M.), The University of Melbourne, Parkville, Victoria, Australia.
AJNR Am J Neuroradiol. 2023 Sep;44(9):1039-1044. doi: 10.3174/ajnr.A7975. Epub 2023 Aug 24.
Volumetric TSE (3D-TSE) techniques are increasingly replacing volumetric magnetization-prepared gradient recalled-echo (3D-GRE) sequences due to improved metastasis detection. In addition to providing a baseline for assessing postcontrast enhancement, precontrast T1WI also identifies intrinsic T1 hyperintensity, for example, reflecting melanin or blood products. The ability of precontrast 3D-TSE to demonstrate intrinsic T1 hyperintensity is not clear from the literature; thus, this study compares precontrast 3D-TSE and 3D-GRE sequences for identifying intrinsic T1 hyperintensity in patients with metastatic melanoma.
Patients with metastatic melanoma and previously reported intrinsic T1 hyperintensity were identified. MRIs were performed at 3T including both 3D-GRE (MPRAGE) and 3D-TSE T1 sampling perfection with application-optimized contrasts by using different flip angle evolution (T1-SPACE) sequences precontrast. Axial 1-mm slices of both T1WI sequences were independently reviewed by 2 neuroradiologists, comparing the conspicuity of each lesion between the 2 sequences according to a 5-point scale and assessing whether the intrinsic T1 hyperintensity was attributable to melanin, blood products, or both.
Twenty examinations were performed, with a total of 214 lesions demonstrating intrinsic T1 hyperintensity. Both readers found that intrinsic T1 hyperintensity was less conspicuous with T1-SPACE compared with MPRAGE for most lesions assessed (81.8%, averaged across both readers), including for lesions with intrinsic T1 hyperintensity attributable to melanin and blood products. Intrinsic T1 hyperintensity was rarely more conspicuous on T1-SPACE (1.4%).
Precontrast intrinsic T1 hyperintensity is more conspicuous with MPRAGE than T1-SPACE. In patients with metastatic melanoma, 3D-GRE should be preferred as the precontrast T1WI sequence when both 3D-TSE and 3D-GRE are performed postcontrast and when not administering IV contrast.
由于提高了对转移瘤的检出率，容积式单次激发快速自旋回波（3D-TSE）技术正逐渐取代容积式磁化准备梯度回波（3D-GRE）序列。除了提供评估增强后对比的基线，对比前 T1WI 也可以识别固有 T1 高信号，例如反映黑色素或血液产物的固有 T1 高信号。然而，文献中并没有明确指出对比前 3D-TSE 技术是否能显示固有 T1 高信号，因此，本研究比较了对比前 3D-TSE 和 3D-GRE 序列在检测黑色素瘤转移患者固有 T1 高信号中的作用。
确定了患有黑色素瘤转移且先前报道有固有 T1 高信号的患者。在 3T 上进行 MRI 检查，包括对比前的 3D-GRE（MPRAGE）和 3D-TSE 应用优化对比 T1 采样完美技术（T1-SPACE）序列。两位神经放射科医生分别对两种 T1WI 序列的轴位 1mm 切片进行独立评估，根据 5 分制比较两种序列中每个病变的显示情况，并评估固有 T1 高信号归因于黑色素、血液产物还是两者都有。
共进行了 20 次检查，共有 214 个病变显示固有 T1 高信号。两位读者发现，对于大多数评估的病变，T1-SPACE 序列显示的固有 T1 高信号比 MPRAGE 序列显示的固有 T1 高信号不明显（平均两位读者均为 81.8%），包括黑色素和血液产物所致的固有 T1 高信号病变。T1-SPACE 上固有 T1 高信号偶尔更明显（1.4%）。
对比前固有 T1 高信号在 MPRAGE 上比 T1-SPACE 上更明显。在黑色素瘤转移患者中，如果在对比后同时进行 3D-TSE 和 3D-GRE，且不使用静脉注射造影剂，则应首选 3D-GRE 作为对比前 T1WI 序列。
