Fuhua Yan

PURPOSE: To assess diagnostic accuracy with diffusion kurtosis imaging (DKI) in patients with breast lesions and to evaluate the potential association between DKI-derived parameters and breast cancer clinical-pathologic factors. MATERIALS AND METHODS: Institutional review board approval and written informed consent were obtained. Data from 97 patients (mean age ± standard deviation, 45.7 years ± 13.1; range, 19-70 years) with 98 lesions (57 malignant and 41 benign) who were treated between January 2014 and April 2014 were retrospectively analyzed. DKI (with b values of 0-2800 sec/mm(2)) and conventional diffusion-weighted imaging data were acquired. Kurtosis and diffusion coefficients from DKI and apparent diffusion coefficients from diffusion-weighted imaging were measured by two radiologists. Student t test, Wilcoxon signed-rank test, Jonckheere-Terpstra test, receiver operating characteristic curves, and Spearman correlation were used for statistical analysis. RESULTS: Kurtosis coefficients were significantly higher in the malignant lesions than in the benign lesions (1.05 ± 0.22 vs 0.65 ± 0.11, respectively; P < .0001). Diffusivity and apparent diffusion coefficients in the malignant lesions were significantly lower than those in the benign lesions (1.13 ± 0.27 vs 1.97 ± 0.33 and 1.02 ± 0.18 vs 1.48 ± 0.33, respectively; P < .0001). Significantly higher specificity for differentiation of malignant from benign lesions was shown with the use of kurtosis and diffusivity coefficients than with the use of apparent diffusion coefficients (83% [34 of 41] and 83% [34 of 41] vs 76% [31 of 41], respectively; P < .0001) with equal sensitivity (95% [54 of 57]). In patients with invasive breast cancer, kurtosis was positively correlated with tumor histologic grade (r = 0.75) and expression of the Ki-67 protein (r = 0.55). Diffusivity was negatively correlated with tumor histologic grades (r = -0.44) and Ki-67 expression (r = -0.46). CONCLUSION: DKI showed higher specificity than did conventional diffusion-weighted imaging for assessment of benign and malignant breast lesions. Patients with grade 3 breast cancer or tumors with high expression of Ki-67 were associated with higher kurtosis and lower diffusivity coefficients; however, this association must be confirmed in prospective studies.

OBJECTIVES: To evaluate the diagnostic value of diffusion-weighted magnetic resonance imaging (DWI) for the characterization of hepatocellular carcinoma (HCC) and dysplastic nodule (DN) in cirrhotic liver, compared with contrast material-enhanced magnetic resonance imaging (CE-MRI). METHODS: A total of 54 patients with 40 HCC and 19 DN lesions were included in our study, and all lesions were histopathologically confirmed. All lesions were evaluated with CE-MRI, and breath-hold DWI was performed with b = 500 s/mm. The signal intensity (SI) of the lesions were classified as low, iso-, slightly high, and strongly high SI compared with that of the surrounding liver parenchyma on DWI for qualitative assessment. Apparent diffusion coefficients (ADCs) and lesion-to-liver ADC ratio of HCCs and DNs were measured and compared by using the Mann-Whitney U test. The lesions were characterized with the use of CE-MRI criteria and DWI, respectively. Receiver operating characteristic analysis was performed to assess the diagnostic value of DWI, CE-MRI, and these techniques combined in the differentiation of HCCs from DNs. RESULTS: In the qualitative analysis, among 40 HCCs, 39 (97.5%) had slightly high or strongly high SI on DWI, and 1 (2.5%) had low SI; only 4 (21.5%) of 19 DNs had slightly high SI, and 15 (78.95%) had iso-SI or low SI. The mean (SD) ADC and ADC ratio for HCCs (1.28 x 10 [0.25] mm/s and 0.88 [0.15], respectively) were significantly lower (P < 0.01 and P < 0.001, respectively) than those for DNs (1.53 x 10 [0.33] mm/s and 1.00 [0.08], respectively). The area, Az, under the receiver operating characteristic curve for the SI feature, the ADC ratio, and the ADCs based on the diagnosis of HCC versus DN were 0.88, 0.81, and 0.68, respectively. When the slightly high SI of lesion with a cutoff ADC ratio less than 0.92 was applied as a criterion, the Az, the sensitivity, the specificity, and the accuracy of DWI for the diagnosis of HCC versus DN were 0.81, 67.50%, 94.74%, and 76.27%, respectively. The corresponding Az, sensitivity, specificity, and accuracy of CE-MRI were 0.70, 82.50%, 57.89%, and 74.58%, respectively. Combined DWI plus CE-MRI had 0.91 Az, 97.50% sensitivity, and 93.22% accuracy, which increased significantly compared with those of CE-MRI alone. CONCLUSIONS: Diffusion-weighted MRI can provide additional information to differentiate HCC from DN. Combined with CE-MRI, DWI allows improved characterization of HCC versus DN in cirrhotic liver.

Purpose To determine the correlation between diffusion kurtosis imaging (DKI)–derived parameters and prognostic factors for rectal adenocarcinoma. Materials and Methods This study was approved by the local institute review board, and written informed consent was obtained from each patient. Data from 56 patients (median age, 59.5 years; age range, 31–86 years) with rectal adenocarcinoma between April 2014 and September 2015 were involved in this prospective study. DKI (b = 0, 700, 1400, and 2100 sec/mm2) and conventional diffusion-weighted imaging (b = 0, 1000 sec/mm2) were performed. Kurtosis and diffusivity from DKI and apparent diffusion coefficients (ADCs) from diffusion-weighted imaging were measured by two radiologists. Student t test, receiver operating characteristic curves, and Spearman correlation were used for statistical analysis. Results Kurtosis was significantly higher in high-grade than in low-grade rectal adenocarcinomas on the basis of both the number of poorly differentiated clusters (PDCs) (1.136 ± 0.086 vs 0.988 ± 0.060, P < .05) and World Health Organization (WHO) grades (1.103 ± 0.086 [standard deviation] vs 1.034 ± 0.103, P < .05). In PDC grading, the diffusivity and ADC were significantly lower in high-grade tumors than in low-grade tumors (1.187 ± 0.150 vs 1.306 ± 0.129 and 1.020 ± 0.113 vs 1.108 ± 0.097, respectively; P < .05) and showed similar correlations with histologic grades (r = −0.486 and r = −0.406, respectively; P > .05). Compared with both diffusivity and ADC, kurtosis showed significantly higher sensitivity (83.3% [20 of 24] vs 70.8% [17 of 24] and 70.8% [17 of 24], respectively) and specificity (96.8% [31 of 32] vs 84.4% [24 of 32] and 81.3% [26 of 32], respectively). Kurtosis showed a better correlation with PDC grades than with WHO grades (r = 0.797 vs r = 0.293, P < .05). Kurtosis was significantly higher in pN1–2 than in pN0 tumors (1.086 ± 0.103 vs 1.009 ± 0.086, P < .05). Conclusion Kurtosis derived from DKI demonstrated a higher correlation with histologic grades compared with diffusivity and ADC. It also showed better performance in differentiating between high- and low-grade rectal adenocarcinomas and between pN1–2 and pN0 tumors. © RSNA, 2016

PURPOSE: To evaluate the added value of single-breathhold diffusion-weighted MRI (DWI) in detection of small hepatocellular carcinoma (HCC) lesions (< or =2 cm) in patients with chronic liver disease, by comparing the detection sensitivity of combined DWI/conventional dynamic contrast-enhanced (DCE)-MRI to that of conventional DCE-MRI alone. MATERIALS AND METHODS: A total of 37 patients with chronic liver diseases underwent abdominal MRI at 1.5T, including T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), and 2D conventional DCE. For each patient study, axial DWI was performed with a single-shot echo-planar imaging (EPI) sequence using a modified sensitivity-encoding (mSENSE) technique with b-value of 500 seconds/mm(2). A total of 20-24 slices were obtained during a 15-17-second breathhold. Two observers independently interpreted the combined DWI/conventional DCE-MRI images and the conventional DCE-MRI images alone in random order. For all small HCC lesions, the diagnostic performance using each imaging set was evaluated by receiver operating characteristic (ROC) curve analysis. Sensitivity and positive predictive values were also calculated and analyzed. RESULTS: A total of 47 small HCCs were confirmed as final result. The area under the ROC curve (Az) of combined DWI/conventional DCE-MRI images (observer 1, 0.922; observer 2, 0.918) were statistically higher than those of conventional DCE-MRI alone (observer 1, 0.809; observer 2, 0.778) for all small HCC lesions (P < 0.01). The lesion detection sensitivities using the combined technique for both observers were significantly higher than those using conventional DCE-MRI alone (P < 0.01). The sensitivity values for two observers using the combined technique were 97.87% and those using conventional DCE-MRI alone were 85.11% to 82.98%. The positive predictive values for two observers using the combined imaging technique (97.87%) were slightly higher than those using conventional DCE-MRI alone (92.86-93.02%), but there was no significant difference between the two imaging sets. CONCLUSION: Combined use of breathhold DWI with conventional DCE-MRI helped to provide higher sensitivities than conventional DCE-MRI alone in the detection of small HCC lesions in patients with chronic liver disease.

PURPOSE: To evaluate the clinical utility of dual energy spectral CT (DEsCT) in staging and characterizing gastric cancers. MATERIALS AND METHODS: 96 patients suspected of gastric cancers underwent dual-phasic scans (arterial phase (AP) and portal venous phase (PP)) with DEsCT mode. Three types of images were reconstructed for analysis: conventional polychromatic images, material-decomposition images, and monochromatic image sets with photon energies from 40 to 140 keV. The polychromatic and monochromatic images were compared in TNM staging. The iodine concentrations in the lesions and lymph nodes were measured on the iodine-based material-decomposition images. These values were further normalized against that in aorta and the normalized iodine concentration (nIC) values were statistically compared. Results were correlated with pathological findings. RESULTS: The overall accuracies for T, N and M staging were (81.2%, 80.0%, and 98.9%) and (73.9%, 75.0%, and 98.9%) determined with the monochromatic images and the conventional kVp images, respectively. The improvement of the accuracy in N-staging using the keV images was statistically significant (p<0.05). The nIC values between the differentiated and undifferentiated carcinoma and between metastatic and non-metastatic lymph nodes were significantly different both in AP (p = 0.02, respectively) and PP (p = 0.01, respectively). Among metastatic lymph nodes, nIC of the signet-ring cell carcinoma were significantly different from the adenocarcinoma (p = 0.02) and mucinous adenocarcinoma (p = 0.01) in PP. CONCLUSION: The monochromatic images obtained with DEsCT may be used to improve the N-staging accuracy. Quantitative iodine concentration measurements may be helpful for differentiating between differentiated and undifferentiated gastric carcinoma, and between metastatic and non-metastatic lymph nodes.