Diffusion-Weighted Imaging of Upper Abdominal Organs Acquired with Multiple B-Value Combinations: Value of Normalization Using Spleen as the Reference Organ

OBJECTIVE: To compare apparent diffusion coefficient (ADC) of the upper abdominal organs acquired with multiple b-value combinations and to investigate usefulness of normalization. MATERIALS AND METHODS: We retrospectively analyzed data, including 3T diffusion-weighted images, of 100 patients (56 men, 44 women; mean age, 63.9) that underwent liver magnetic resonance imaging. An ADC map was derived with the following six b-value combinations: b1 = 0, 50, 400, 800; b2 = 0, 800; b3 = 0, 50, 800; b4 = 0, 400, 800; b5 = 50, 800; and b6 = 50, 400, 800 s/mm2. ADC values of the right liver lobe, left liver lobe, spleen, pancreas, right kidney, and left kidney were measured. ADC values of the spleen were used for normalization. Intraclass correlation coefficients (ICCs), comparison of dependent ICCs, and repeated-measures analysis of variance were used for statistical analysis. RESULTS: Intraclass correlation coefficients of the original ADC revealed moderate to substantial agreement (0.5145–0.6509), while normalized ADCs revealed almost perfect agreement (0.8014–0.8569). ICC of normalized ADC for all anatomical regions revealed significantly less variability than that of the original ADC (p < 0.05). Coefficient of variance for normalized ADC was significantly lower than that for the original ADC (3.0.3.8% vs. 4.8.8.8%, p < 0.05). CONCLUSION: Normalization of the ADC values of the upper abdominal organs using the spleen as the reference organ significantly decreased variability in ADC measurement acquired with multiple b-value combinations.

Diagnostic values of normalized ADC value in benign and malignant breast lesions / 实用放射学杂志

Objective To evaluate the values of DWI normalized ADC value in breast MRI in the differential diagnosis of benign and malignant breast lesions.Methods The absolute value of ADC,normalized ADC value and T1 WI dynamic contrast-enhanced TIC were analyzed in 49 patients with benign and malignant breast lesions;the efficiencies of single method diagnosis and combined diagnosis were assessed.Results When b=1 000 s/mm2 ,the absolute value of ADC <1.25×10 -3 mm2/s was taken as the thresh-old value for the diagnosis of malignant breast lesions,the area under the ROC curve was 0.818,the sensitivity was 73.9% and the specificity was 84.6%;the normalized ADC value <0.55 × 10 -3 mm2/s was taken as the diagnostic threshold,the area under the ROC curve was 0.901,the sensitivity was 87.0% and the specificity was 88.5%,there was a significant difference between both values.The lesions with a wash-out type of T1 WI dynamic contrast-enhanced TIC were diagnosed as malignant lesions,the sensitivi-ty was 89.5% and the specificity was 70.0%.The absolute value of ADC and T1 WI dynamic contrast-enhanced TIC were applied combinedly,the predicted percentage correct was 81.6% for the diagnosis of breast lesions,while the normalized ADC value and T1 WI dynamic contrast-enhanced TIC were applied combinedly,the predicted percentage correct was increased,which was 89.8%. Conclusion Normalized ADC value has a higher sensitivity and specificity in differentiating benign and malignant breast lesions,its combined application with T1 WI dynamic contrast-enhanced TIC can improve the diagnostic performance of breast lesions.