| Objectives:The purpose of this study was to investigate the artifact, SNR and ADC value of normal pancreas and C, CNR and ADC value of pancreatic cancer among different DWI sequences on 3.0T MR scanner.Materials and Methods:15 normal volunteers underwent ordinary T1WI, T2WI with Fatsat, MRCP, DWI and non-enhanced LAVA on 3.0T.30 patients with pancreatic cancer proven by histopathology underwent ordinary T1WI, T2WI with Fatsat, MRCP, DWI non-enhanced and enhanced LAVA before operation on 3.0T. Based on SE-EPI sequence and b values=0 and 600 s/mm2, DWI sequences included breath-hold DWI with MPG pulses in X,Y,Z direction(BH600ALL), breath-hold DWI with MPG pulses in Z direction(BH600SI), respiratory-triggered DWI with MPG pulses in X,Y,Z direction(TRIG600), respiratory-triggered DWI with MPG pulses in X,Y,Z direction and inversion recovery for fat saturation (TRIG600+BS), free-breathing DWI with MPG pulses in X,Y,Z direction and inversion recovery for fat saturation (FB600+BS) and breath-hold DWI with MPG pulses in X,Y,Z direction and inversion recovery for fat saturation (BH600+BS). Artifacts, SNR and ADC value of normal pancreas and C, CNR and ADC value of pancreatic cancer were statistically investigated and compared among different DWI sequences.Results:1 On different DWI sequences, normal pancreas displayed four types of artifacts: fishtail lines, follicle like blotch, salt-and-pepper shadow and discontinuing or abscent appearances. Artifacts of normal pancreas showed noticeably statistical difference among different DWI sequences by ANOVA(p<0.001). Normal pancreas displayed the lowest artifact scores, edge sharpness and homogeneous hypointensity in TRIG600+BS, indefinite outline in FB600+BS, heterogeneous hyperintensity in TRIG600 and the highest artifact scores in BH600+BS. 2 SNR of normal pancreas showed noticeably statistical difference among BH600ALL,BH600SI,TRIG600,TRIG600+BS,FB600+BS and BH600+BS DWI sequences (p<0.001); Among six different DWI sequences, TRIG600 had the highest SNR, while BH600+BS had the lowest SNR. The head, body and tail of pancreas had the increasing SNR in all six different DWI sequences and the statistical difference in SNR was noticed between the head and tail of pancreas(p<0.05); SNR of normal pancreas in TRIG600+BS and TRIG600 was more accurately correlated to the distance between the physiological location of the head, body and tail of pancreas within the body and the surface coil.3 ADC value of normal pancreas showed noticeably statistical difference among BH600ALL,BH600SI,TRIG600,TRIG600+BS and FB600+BS DWI sequences (p <0.001); Among those five different DWI sequences, FB600+BS had the highest ADC value, while BH600SI had the lowest ADC value. ADC value of the head, body and tail of pancreas appeared statistical difference in each DWI sequence (p<0.05); ADC value in the head of pancreas was the lowest compared to that in the body and tail of pancreas and the statistical difference in ADC value was noticed between the head and tail of pancreas on each DWI sequence (p<0.05).4 CNR and C of pancreatic cancer displayed noticeably statistical difference among BH600ALL,BH600SI,TRIG600,TRIG600+BS and FB600+BS DWI sequences by ANOVA(p<0.001 and p=0.001 respectively). Among those five different DWI sequences, CRN of pancreatic cancer in TRIG600 was the highest but had no statistical difference with that in TRIG600+BS, while C of pancreatic cancer in TRIG600+BS was the highest and had statistical difference with that in TRIG600(p=0.036).5 ADC value of pancreatic cancer had no statistical difference among BH600ALL,BH600SI,TRIG600,TRIG600+BS and FB600+BS DWI sequences by Kruskal-Wallis test(p=0.095). For BH600ALL and BH600SI, there were no statistical difference among ADC value of pancreatic cancer, adjacent pancreatic tissue and distal pancreatitis by ANOVA. While for all TRIG600, TRIG600+BS and FB600+BS, there were statistical difference among ADC value of pancreatic cancer, adjacent pancreatic tissue and distal pancreatitis by ANOVA (p values were 0.010,0.000002 and 0.000006 respectively); ADC value of pancreatic cancer was statistically lower than that of adjacent pancreatic tissue and distal pancreatitis on all TRIG600, TRIG600+BS and FB600+BS (p<0.05), while there was no statistical difference in ADC value between adjacent pancreatic tissue and distal pancreatitis on TRIG600, TRIG600+BS and FB600+BS DWI sequences (p>0.05).Conclusion:The normal pancreas in TRIG600+BS displayed homogeneous hypointensity, edge sharpness and the superior image quality compared to other five DWI sequences on 3.0T MR. SNR of The normal pancreas in TRIG600+BS was high enough for imaging observing and accurately reflected physiological location of the head, body and tail of pancreas within the body. The disproportional ADC values of normal pancreas in TRIG600+BS disclosed the feature of its linear organ for pancreas. Compared to other five DWI sequences, higher C and CNR of pancreatic cancer in TRIG600+BS help to detect the lesion, depict its outline and definition, and its ADC value could better disclose histopathological state in pancreatic cancer, adjacent pancreatic tissue and distal pancreatitis.Objective:With a comparison of breath-hold DWI, to investigate the value of Respiratory-triggered Diffusion-weighted MR imaging with background body signal suppression (DWIBS) for diagnosis and differential diagnosis of solid pancreatic masses at 3.0T.Materials and Methods:15 normal volunteers underwent ordinary T1WI, T2WI with Fatsat, MRCP, DWI and non-enhanced LAVA on 3.0T.58 patients, including 30 cases of pancreatic cancer (proven by histopathology),9 cases of mass-like pancreatitis(4 cases proven by histopathology,5 cases proven by follow-up after treatment),9 Cases of solid pseudopapillary tumor of pancreas(SPTP, proven by histopathology) and 10 cases of pancreatic neuroendocrine tumor(PET, proven by histopathology), underwent ordinary T1WI, T2WI with Fatsat, MRCP, DWI, non-enhanced and enhanced LAVA before operation or treatment on 3.0T. Based on SE-EPI sequence and b values=0 and 600, DWI sequences included breath-hold DWI with MPG pulses in X,Y,Z direction(BH600ALL) and respiratory-triggered DWI with MPG pulses in X,Y,Z direction and inversion recovery for background body signal suppression (TRIG600+BS). ADC value of normal pancreas and all types of pancreatic lesions were statistically investigated and compared for diagnosis and differential diagnosis in the two DWI sequences. ROC curve was used to analyze the power of differential diagnosis in the two DWI sequences.Results:1 For BH600ALL DWI sequence, statistical difference were noticed among ADC value of normal pancreas, mass-like pancreatitis, pancreatic cancer, SPTP and PET by Kruskal-Wallis Test(p=0.001). PET had the highest ADC value, then followed by pancreatic cancer, normal pancreas, mass-like pancreatitis and SPTP. Games-Howell Test showed that ADC value of pancreatic cancer was statistically higher than that of mass-like pancreatitis(p=0.019), but had no statistical difference with that of normal pancreas. There was no statistical difference between ADC value of mass-like pancreatitis and that of normal pancreas. There was no statistical difference between ADC value of SPTP and that of PET. ADC value of SPTP was statistically lower than that of that of pancreatic cancer and normal pancreas(p=0.001 and 0.029 respectively). ADC value of PET had no statistical difference with that of any other pancreatic lesions.2 For TRIG600+BS DWI sequence, distinguished statistical difference were noticed in ADC value among normal pancreas, mass-like pancreatitis, pancreatic cancer, SPTP and PET by ANOVA (p<0.001). Normal pancreas had the highest ADC value, then followed by PET, pancreatic cancer, mass-like pancreatitis and SPTP. LSD test showed there were noticeably statistical difference in ADC value among pancreatic cancer, mass-like pancreatitis and normal pancreas (p<0.001). ADC value of SPTP was statistically lower than that of PET (p=0.000018). ADC value of SPTP is statistically lower than that of that of pancreatic cancer and normal pancreas(p=0.000003 and p=0.000000 respectively), but had no statistical difference with that of mass-like pancreatitis. ADC value of PET was statistically lower than that of that of normal pancreas and higher than that of mass-like pancreatitis. (p=0.036 and p=0.000930 respectively), but had no statistical difference with that of pancreatic cancer.3 Independent t test showed there was no statistical difference in ADC value between BH600ALL and TRIG600+BS. Paired t test displayed that ADC value of normal pancreas in BH600ALL was statistically lower than that in TRIG600+BS (p< 0.001), while there were no statistical difference in ADC value among any other DWI sequences.ROC curve disclosed that confidence intervals of ADC value in both BH600ALL and TRIG600+BS mostly overlapped among different pancreatic entities and their areas under curve both DWI sequences had statistical difference with the area under curve 0.5, when using ADC value for differential diagnosis of pancreatic cancer and SPTP from other pancreatic masses. For differential diagnosis of mass-like pancreatitis from other pancreatic lesions, the area under curve of ADC value in TRIG600+BS had statistical difference with the area under curve 0.5(p=0.005), while the area under curve of ADC value in BH600ALL had no statistical difference with the area under curve 0.5(p=0.053). For differential diagnosis of PET from other pancreatic masses, areas under curve of ADC value in both BH600ALL and TRIG600+BS had no statistical difference with the area under curve 0.5. For differential diagnosis between pancreatic cancer and mass-like pancreatitis and between SPTP and PET, confidence intervals of ADC value in both BH600ALL and TRIG600+BS mostly overlapped and their areas under curve both had statistical difference with the area under curve 0.5.Conclusion:Compared to BH600ALL, ADC values in TRIG600+BS could better disclose histopathological pattern of normal pancreas and pancreatic lesions and might be helpful in differential diagnosis of all types of pancreatic entities.Objective:To investigate the microcirculation and microvasculature in pancreatic cancer by pharmacokinetic analysis of Gd-DTPA-enhanced MR PWI at 3.0T.Materials and Methods:20 healthy volunteers and 25 patients with pancreatic cancer proven by histopathology underwent MR PWI using LAVA sequence with T1 contrast at a 3.0T scanner. The T1 measurement was carried out before the injection of contrast agent using the same LAVA sequence with small flip angle. The temporal resolution was 30s. The spatial resolution was 224x224 and then reconstructed into 512×512. A two compartment model was used to quantify perfusion parameters including Ktrans, Kep and Ve in pancreatic cancer, adjacent pancreatic tissue(proximal to cancer), distal pancreatitis and normal pancreas in volunteers (the head, body and tail of pancreas). All parameters among different tissues were statistically analyzed and compared. Results:PWI was successfully carried out on 15 of 20 volunteers and 18 of 25 patients. All three perfusion parameters (Ktrans, Kep and Ve) had no statistic difference among the head, body and tail of normal pancreas. Characteristics of Ktrans highly agreed with those of Kep among different tissues:adjacent pancreatic tissue had the biggest Ktrans (3.769±2.67 min-1) and Kep (5.636±5.64 min-1),and then followed by normal pancreas (2.688±1.469 and 4.278±3.23 min-1),pancreatic cancer (1.663±1.25 and 2.526±3.55 min-1) and distal pancreatitis (1.162±0.94 and 1.700±1.90 min-1); One-way analysis of variance showed that both of Ktrans and Kep had statistic differences among different tissues and their p values were 0.000075 and 0.006 respectively; Both of Ktrans (p=0.011 and p=0.002 respectively) and Kep (p=0.013 and p=0.021 respectively) in pancreatic cancer were statistically lower than those in normal pancreas and adjacent pancreatic tissue, while neither of Ktrans and Kep had statistic difference between pancreatic cancer and distal pancreatitis; Both of Ktrans (p=0.000073 and p=0.000335 respectively) and Kep (p=0.006 and p=0.009 respectively) in distal pancreatitis were statistically lower than those in normal pancreas and adjacent pancreatic tissue. Pancreatic cancer had the biggest Ve (0.896±0.10), and then followed by adjacent pancreatic tissue (0.824±0.15), distal pancreatitis (0.787±0.20) and normal pancreas (0.599±0.25); Kruskal-Wallis Test showed Ve had statistic differences among different tissues(p=0.007). Ve in pancreatic cancer was statistically larger than that in normal pancreas(p=0.002), while Vehad no statistic differences between any other tissues.Conclusion:Pharmacokinetic analysis of Gd-DTPA-enhanced MR PWI at 3.0T could be technically feasible to evaluate the microcirculation and microvasculature in pancreatic Cancer. Compared to normal pancreas, pancreatic cancer usually had a lower Ktrans, Kep and larger Ve.Objectives:To prospectively identify metabolic features of pancreatic carcinoma and normal pancreas by in vivo proton (hydrogen 1) magnetic resonance (MR) spectroscopy at 3.0 T.Materials and Methods:Averagely age-matched 28 healthy volunteers and 25 patients with pancreatic carcinoma in the head of pancreas confirmed by histopathology underwent axial, coronal and saggital respiration-triggered T2 weighted imaging for location of the single voxel. Respiration-triggered 1H MR spectroscopy were used for detection of metabolites within the head of normal pancreas and cancerous tissue. All spectra data were processed in a SAGE software. The un-suppressed internal water at 4.7ppm was used as an internal reference for determination of metabolite concentrations. Each ratio among the different peak areas was statistically evaluated between normal pancreas and pancreatic carcinoma.Results:The following four main groups of spectra were detected:the peak of fatty acids at 5.4ppm, residual water at 4.7ppm, choline metabolites at 3.2ppm and lipids at 1.3ppm. Ratios of lipid/water without water suppression (6.754×10-3±0.007) and choline/internal water (1.897×10-3±0.002) in normal pancreas were greater than those in pancreatic cancer(3.162×10-3±0.004, p=0.039; 0.544×10-3±0.001, p=0.000013) respectively. The ratio of fatty acids/lipid in normal pancreas (40.349×10-3±0.057) was smaller than that in pancreatic cancer (102.904×10-3±0.140, p=0.028). Ratios of fatty acids/internal water and choline/lipid didn't reach statistical difference.Conclusion:Compared to normal pancreas, the decreased ratios of lipid/water without water suppression and choline/internal water and higher ratio of fatty acids/lipid might be suggested as metabolic features of pancreatic carcinoma at 3.0T. |
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