ABSTRACT
Objective To determine the significance of the quantitative parameters obtained from intravoxel incoherent motion ( IVIM) diffusion weighted imaging ( DWI) in differentiating renal tumors from normal renal tissues.Methods Twenty-four patients with surgical pathology-proven renal tumors and 13 volunteers with healthy kidneys were included.DWI was performed with 9 b-values (0, 20, 50, 100, 200, 400, 600, 800 and 1 000 s/mm2).The slow component of diffusion (Dslow), fast component of diffusion ( Dfast ) and fraction of fast ADC ( f) of the biexponential DWI were calculated for the clear cell renal cell carcinoma (CCRCC), the normal renal parenchyma and the non CCRCC ( NCCRCC) .The ADC was calculated for all b-values using linear regression yielding standard ADC ( ADCtot ) .The parameters were compared among the groups, and the receiver operating characteristic ( ROC ) analysis was performed. Results CCRCC showed higher ADCtot (1.73 ±0.43) ×10 -3 mm2/s, Dfast (14.75 ±14.73) ×10 -3 mm2/s, Dslow(1.34 ±0.38) ×10 -3 mm2/s than NCCRCC (ADCtot(1.23 ±0.26) ×10 -3 mm2/s, Dfast(9.47 ± 5.27) ×10 -3 mm2/s, Dslow(0.58 ±0.15) ×10 -3 mm2/s), and the differences of ADCtot(P=0.037) and Dslow(P=0.001) were significant.The normal renal parenchyma showed higher ADCtot (2.25 ±0.11) × 10 -3 mm2/s, Dslow ( 1.74 ±0.17 ) ×10 -3 mm2/s, f ( 35.00% ±9.37%) than CCRCC ( f, 31.13% ± 10.75%) and NCCRCC(f, 33.76%±24.02%), and the differences between the normal renal parenchyma and CCRCC of ADCtot ( P =0.000 ) and Dslow ( P =0.001 ) were significant.There were no differences between the normal renal parenchyma and the tumor ipsilateral renal parenchyma of all parameters.Dslow had higher accuracy ( sensitivity 95%, specificity 100%) in distinguishing CCRCC and NCCRCC, with area under the curve of 0.988.Conclusions Multi-b-value DWI derived quantitative parameters including ADCtot and Dslow may differ significantly between the renal tumor and normal renal parenchyma.Dslow is the best parameter in distinguishing CCRCC and NCCRCC.
ABSTRACT
Objective To investigate the effect of gender and age on the apparent diffusion coefficient (ADC) of normal adult pancreas.Methods A total of 383 patients with normal pancreas (290 male,93 female,range from 21 to 78 years of age) were enrolled in this study.The subjects were divided into four groups based on different age (≤40 years,41-50 years,51-60 years and ＞60 years) with patient number of 56,108,139 and 80,respectively.Breath-hold single-shot echo-planar DWI (b value =0,500 s/mm2) was performed to determine ADCs on all patients.The average ADCs was calculated by four ADCs measured from the head to tail part of the pancreas in each patient.Patients with different age or gender were analyzed by independent-samples t test.Effect of gender on ADCs was analyzed using the Mann-Whitney U test.Relationship between ADCs and age was analyzed using Spearman rank-order correlation test,and Kruskal-Wallis H test was used to compare the ADCs among 4 age groups.Results The median pancreatic ADC values in female group(n =93) [1.60 × 10-3 mm2/s (1.47 × 10-3-1.77 × 10-3) mm2/s] was higher than that in male group (n =290) [1.57 × 10-3mm2/s(1.41 × 10-3-1.74 × 10-3)mm2/s].Mann-Whitney U test results showed the mean ADCs was similar between the two groups (Z =1.335,P =0.182).The age distribution was similar between the male [(52 ± 10) years of age] and female [(51 ± 11) years of age]groups (t =0.267,P=0.790).The age spectrum showed that there was no correlation between the average ADC values and age (r =0.016,P =0.752).The median ADC values of the four age groups were 1.58 ×10-3,1.54 × 10-3,1.59 × 10-3 and 1.57 × 10-3 mm2/s,respectively.Kruskal-Wallis H test showed no significant difference of mean ADCs among the age groups (x2 =2.15,P =0.542).Conclusion There is no correlation of ADCs between age and gender in normal adult pancreas.
ABSTRACT
Objective To investigate the characteristics of minimal fat renal angiomyolipoma (MFAML)and clear cell renal cell carcinoma(CCRCC)in high resolution multi-slice spiral CT(MSCT)and to improve the diagnosis accuracy for the renal tumors.Methods A retrospective analysis was performed on 24 MFAML patients(16 females,8 males)with mean age of 43(19-74)years and 24 CCRCC patients(16 females,8 males)with mean age of 44(21-76)years.All patients had undergone MSCT and proved histopathologically after surgery.The characteristics included tumor location,tumor attenuation on unenhanced CT,enhancement characteristics(degree of tumor enhancement in the early corticomedullary phase,homogeneity of enhancement,amount of enhancement,enhancement pattern over time),tumor margin,intratumoral calcification,and perinephric changes.The predictive value of each CT characteristic was determined by using multivariate logistic regression analysis.Results The tumor location in the kidney (upper pole:MFAML,6 cases,CCRCC,6 cases;middle:MFAML,7 cases,CCRCC,9 cases;lower pole:MFAML,11 cases,CCRCC,9 cases)and smooth tumor margin(MFAML,n=21;CCRCC,n=19)were not significantly different between MFAML patients and those with CCRCC,P＞0.05.Twenty-one cases of both MFAMLs and CCRCCs had the significant enhancement in the early corticomedullary phase,which were hypovascular tumors,whereas the mean amount of tumor enhancement was greater in CCRCC than in MFAML in both the early corticomedullary and the corticomedullary phases(CCRCC:175 HU,196 HU;MFAML:125 HU,145 HU;P＜0.05.MFAML usually showed homogeneous enhancement(n=15)rather than heterogeneous enhancement(n =9),whereas most CCRCC showed heterogeneous enhancement(n =17)rather than homogeneous enhancement(n =7),P＜0.05).Enhancement pattern was not a significant predictor.Within the 13 MFAML cases,8 cases had sufficient blood supply(6 cases showed obvious wash-in-and-wash-out,2 cases were with prolonged enhancement),5 cases with hypovascular showed a pattern of prolonged or gradual enhancement,while 21 CCRCC cases had sufficient blood supply and 71％ of them showed obvious wash-in-and-wash-out.High tumor attenuation on unenhanced scans(MFAML:17 patients (75％);CCRCC:2 patients(8％),P=0.002,OR=0.010)and threshold enhancement values of 129.5 HU in the corticomedullary phase(MFAML:5 patients(20％);CCRCC:20 patients(83％),P =0.004,OR =0.057)were valuable predictors for differentiating MFAML from CCRCC at multivariate logistic regression analysis.Conclusions MSCT is useful in differentiating MFAML from CCRCC,with high tumor attenuation on unenhanced scans and threshold enhancement values of 129.5 HU in the corticomedullary phase being the most valuable CT findings.75％ of MFAMLs with sufficient blood supply also show a pattern of wash-in-and-wash-out,which can easily misdiagnosed as a renal cancer.