MR多参数成像评估慢性胰腺炎临床分级的价值

目的 探讨应用多种MRI技术评估慢性胰腺炎(CP)临床分级的价值.方法 纳入经病理和临床随访证实的65例CP患者,按M-annheim分级分为轻度组(14例)、中度组(37例)和进展组(14例),并以20例健康志愿者作为对照.在上腹部常规T1WI及T2WI抑脂扫描后,进行胰腺MRCP检查及胰腺动态MR检查.测量T1WI、T2WI加权扫描的胰腺实质信号及肝脏信号,获取它们的比值(rT1、rT2),根据MRCP测量主胰管最大直径(MPD),并对胰腺病变进行评估、分类;测量动态MR增强时胰腺实质信号值,并计算强化率;ROC分析MRI表现与CP临床分级的相关性.结果 正常、轻度、中度和进展组rT1分别为0.98±0.27、0.84±0.12、0.81±0.16和0.75±0.24,中度、进展组较正常组明显降低(P<0.01);rT2分别为1.28±0.30、1.46±0.44、1.46±0.55和1.76±0.72,各组间无统计学差异;MPD为(2.0±0.6)mm、(5.4±2.4)mm、(6.5±3.3)mm和(8.1±4.1)mm,各组间差异显著(P值均<0.01).轻度、中度和进展组的剑桥重度分级分别有4例(29%)、33例(90%)和13例(93%),差异显著(P<0.01);胰管结石分别有2例(14%)、11例(30%)和5例(36%),胰腺假性囊肿分别有0例、6例(16%)和3例(21%),胰腺萎缩分别有4例(29%)、22例(60%)和10例(71%),各组间均无统计学差异.正常、轻度、中度和进展组的胰腺动态增强扫描实质期与动脉期胰腺信号强化率比值(P/A)分别为0.88±0.08、1.10±0.08、1.37±0.15和1.48±0.53,各组间差异显著(P<0.05).rT1值、剑桥分级、胰管直径及P/A比值与临床分级均有相关性(r值分别为0.34、0.41、0.62、-0.43).ROC分析显示,MPD>2.5 mm、rT1<0.8、P/A>0.8诊断CP均有较好的敏感性和特异性,三者结合时诊断CP的特异性可提高到95%.结论 应用磁共振的T1WI、MRCP及动态增强检查能准确、良好地评估CP的严重程度,其中MRCP的敏感性及特异性最高,其次是动态增强检查与T1平扫.

Evaluation of MR multiparameter imaging for clinical classification of chronic pancreatitis

Objective To investigate the value of MR multiparameter imaging for the clinical classification of chronic pancreatitis. Methods 65 patients with confirmed chronic pancreatitis by follow-up and pathologic examinations ( 14 mild, 37 moderate and 14 severe according to MANNHEIM system) and 20healthy volunteers were included in this study. MR examination including routine T1WI, T2WI, MRCP and dynamic enhanced MRI. The data were measured and statistical analysis was applied in four groups. Two radiologists assessed pancreatic duct diameter, pancreatic size, pancreatic cyst, pancreatic stone and pancreatic signal intensity on MRCP, T1-weighted and T2-weighted images. Pancreatic signal intensity were also measured on dynamic enhanced MR. Results Mean values of pancreatic signal intensity ratio on T1WI (rT1)in the pancreas were significantly reduced in patients with moderate and severe CP compared with volunteers.There was significant difference among four groups ( normal, 0. 98 ±0.27; mild, 0. 84 ±0. 12; moderate,0.81 ±0. 16; severe, 0.75 ±0.24). Mean values of pancreatic signal intensity ratio on T2WI (rT2) in the pancreas were no difference among four groups ( normal, 1.28 ± 0.3; mild, 1. 46 ± 0. 44, moderate, 1.46 ±0.55; severe, 1.76 ± 0.72). Pancreatic duct diameters were significantly increased in mild, moderate and severe CP groups mild (5.3 ± 2.4) mm; moderate ( 6.5 ± 3.3 ) mm; severe ( 8.1 ± 4.1 ) mm ] compared with patients without CP (2.0 ±0.6) mm; P < 0.01 ]. Severe degree of Cambridge classification was graded as mild in 4 (29%), moderate in 33 (89%), severe in 13 (93%). Pancreatic calcification was graded as mild in 2 ( 14% ), moderate in 11 (30%), severe in 5 (36%). Pancreatic pseudocyst was graded as mild in 0, moderate in 6 ( 16% ), severe in 3 (21.43%). Pancreatic parenchymal atrophy was graded as mild in 4 (29%), moderate in 22 (59%), severe in 10 (71%). They did not vary among CP groups. Parenchymal/arterial phase enhanced ratio (P/A) in the pancreas were significantly increased in patients with mild,moderate and severe CP (mild, 1. 10 ±0.08; moderate, 1.37 ±0.15; severe, 1.48 ±0.53) compared with patients without CP (0.88 ± 0.08, P < 0. 05 ). Significant correlation was present between the severity level of CP and the change of rT1, severe degree of Cambridge classification, the pancreatic duct diameter and P/A (r=0. 34, 0.41, 0. 62, - 0. 43; P < 0. 01 ). ROC analysis showed the presence of pancreatic duct diameters more than 2.5mm, rT1 less than 0. 8 and P/A more than 0. 8 had a sensitivity and specificity of diagnosing chronic pancreatitis of 94% and 79%, 90% and 48%, 95% and 47% respectively. Combined with the three variables, the specificity of diagnosing chronic pancreatitis can be improved to 95%.Conclusions T1-weighted, MRCP and dynamic enhanced MRI imaging can accurately evaluate the clinical severity of chronic pancreatitis. MRCP had the highest sensitivity and specificity, followed by T1-weighted and dynamic enhanced MRI imaging.