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目的探讨兔肝 VX_2瘤种植后 MR 扩散加权成像(DWI)的价值、动态特征及其病理机制。方法新西兰大白兔40只,采用开腹下块种植法行肝内 VX_2瘤种植,其中25只种植1个部位、15只种植2个部位。对全部种植兔于种植后第7、14、21天行 DWI 和第7、14天行常规 MRI(T_1WI、T_2WI)检查,并对其中10个肿瘤标本行病理检查。结果种植后第7天 DWI、T_1WI、T_2WI 病灶发现率分别为78.7%(37/47)、10.7%(3/28)、53.6%(15/28),差异有统计学意义(χ~2=32.61,P<0.01);第14天分别为95.7%(45/47)、54.3%(19/35)、82.9%(29/35),差异有统计学意义(χ~2=21.50,P<0.01)。种植后7 d 肿瘤生长较慢,内部尚未坏死,信号均匀;约14 d 后肿瘤生长开始加速,但此时内部坏死仍不明显,呈等或不均匀信号;第21天时肿瘤内部出现明显坏死,DWI 上呈不均匀信号,成活肿瘤部分呈高信号,肿瘤坏死部分呈低信号,而囊变、液化部分呈高信号;从第7天至第21天,肿瘤边界逐渐由不清楚至清楚,内部信号由均匀至不均匀。敏感梯度因子(b)值为100 s/mm~2时,种植后第7、14及21天,肿瘤周围表观扩散系数(ADC)值分别为(2.18±0.29)×10~(-3)、(1.96±0.33)×10~(-3)与(1.80±0.35)×10~(-3)mm~2/s,而肿瘤周围正常肝实质 ADC 值分别为(2.82±0.36)×10~(-3)、(2.61±0.40)×10~(-3)与(2.75±0.43)×10~(-3)mm~2/s。结论 VX_2瘤成活与坏死、囊变部分 DWI 具有典型表现,同时 DWI 在早期发现病变方面有重要潜在的价值。
Objective To investigate the value, dynamic characteristics and pathological mechanism of MR diffusion weighted imaging (DWI) after implantation of VX 2 tumor in rabbits. Methods Forty New Zealand white rabbits were enrolled in this study. Intrahepatic VX2 tumors were implanted under open laparotomy, of which 25 were planted with 1 site and 15 were planted with 2 sites. All rabbits were implanted with DWI on the 7th, 14th and 21st day after implantation and routine MRI (T 1WI, T 2 WI) on the 7th and 14th day after implantation. Pathological examination was performed on 10 of them. Results The detection rates of DWI, T_1WI and T_2WI on day 7 were 78.7% (37/47), 10.7% (3/28) and 53.6% (15/28), respectively, with significant difference (χ ~ 2 = 32.61, P <0.01). On day 14, they were 95.7% (45/47), 54.3% (19/35) and 82.9% (29/35) respectively, with significant difference (χ ~ 2 = 21.50, P < 0.01). After 7 days of planting, the tumor growth was slow, the internal was not yet necrosis, the signal was uniform; tumor growth started to accelerate after about 14 days, but the internal necrosis was still not obvious at this time, showing equal or uneven signal; on the 21st day, DWI showed a non-uniform signal, the survival of the tumor was high signal, tumor necrosis was low signal, and cystic change, liquefaction part was high signal; from the 7th to the 21st day, the tumor boundary gradually from unclear to clear, internal Signal from uniform to uneven. The apparent diffusion coefficient (ADC) values around the tumor were (2.18 ± 0.29) × 10 ~ (-3) on the 7th, 14th and 21st days after the sensitive gradient factor (b) value was 100 s / , (1.96 ± 0.33) × 10 -3 and (1.80 ± 0.35) × 10 -3 mm 2 / s respectively. The ADC values of normal liver parenchyma around the tumor were (2.82 ± 0.36) × 10 ~ (2.61 ± 0.40) × 10 ~ (-3) and (2.75 ± 0.43) × 10 ~ (-3) mm ~ 2 / s, respectively. Conclusion The survival and necrosis of VX_2 tumors are typical, and DWI of cystic lesions is typical. DWI has important potential value in the early detection of lesions.