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目的比较3.0 T MR全身扩散加权成像(WB-DWI)与正电子发射计算机断层显像(PET)/CT成像在兔肝VX2瘤的诊断及淋巴结转移、远处转移评估中的价值与限度,探寻一种更为经济、实用的肝癌影像诊断、鉴别诊断与临床分期的影像检查方法。方法采用开腹直视下瘤块接种法,将成功建模的16只实验兔随机分为3组(14天组6只、28天组6只、42天组4只)。在对应的时间内,采用Philips 3.0 T-Achieva/Intera双梯度超导高场强MR扫描仪及Philips 16 TOF PET/CT扫描仪行MR WB-DWI及PET/CT检查。检查结束后处死实验兔进行尸检,比较两种成像方法对肝内原发病灶及远处转移灶的检出情况。结果 14天组直径在5 mm左右的兔肝VX2瘤PET/CT不能检出,在WB-DWI上不易辨认,其诊断需结合DWI横断图像。28天组和42天组直径>1.0 cm的兔肝VX2瘤WB-DWI、PET/CT两种检查方法均能检出;在转移灶的检出方面,PET仅能发现直径>1.0 cm的转移灶,而WB-DWI则能检出PET不能发现的肝内、肺内直径<1.0 cm的小转移灶,对纵隔、腹腔、腹膜后淋巴结的检出率也明显高于PET。结论 PET/CT受其空间分辨率等因素的限制,对直径<1.0 cm的VX2瘤及转移灶检出率低,存在假阴性结果;3.0 T MR WB-DWI与PET/CT相比,具有无需注射对比剂、无电离辐射、价格低廉等优势,且对小转移灶及淋巴结的显示敏感性更高,具有极大的临床价值与广阔的应用前景,可作为肿瘤全身筛查方法的一种补充。
Objective To compare the value and limit of 3.0 T MR whole body diffusion weighted imaging (WB-DWI) and positron emission tomography (PET) / CT imaging in the diagnosis of rabbit liver VX2 tumor and lymph node metastasis and distant metastasis A more economical and practical imaging diagnosis of liver cancer, differential diagnosis and clinical staging of imaging methods. Methods Sixteen experimental rabbits were randomly divided into three groups (6 in 14-day group, 6 in 28-day group and 4 in 42-day group). At the corresponding time, MR WB-DWI and PET / CT were performed using the Philips 3.0 T-Achieva / Intera dual gradient superconductor high-field MR scanner and the Philips 16 TOF PET / CT scanner. At the end of the experiment, the rabbits were sacrificed and autopsied. The detection of primary and distant liver metastases by two imaging methods was compared. Results The PET / CT of rabbit liver VX2 tumor with a diameter of about 5 mm could not be detected on the 14th day. It was not easy to identify on the WB-DWI. The diagnosis of this disease required the combination of DWI transection images. The detection of WB-DWI and PET / CT in 28-day and 42-day rabbit liver VX2 tumors with a diameter of 1.0 cm were both detectable. On the detection of metastases, PET only found metastases> 1.0 cm in diameter However, WB-DWI detected small intrahepatic and intrapulmonary lesions with a diameter of less than 1.0 cm that PET could not detect. The detection rate of mediastinal, abdominal and retroperitoneal lymph nodes was also significantly higher than that of PET. Conclusions The PET / CT is limited by its spatial resolution and other factors. The detection rate of VX2 tumors and metastases with a diameter of <1.0 cm is low with false-negative results. Compared with PET / CT, Injection of contrast agent, no ionizing radiation, low price and other advantages, and the sensitivity of the small metastases and lymph nodes display higher, with great clinical value and broad application prospects, can be used as a complement to the tumor screening method .