Differentiation of pyogenic hepatic abscesses from malignant mimickers using multislice-based texture acquired from contrast-enhanced computed tomography.

BACKGROUND: Pyogenic hepatic abscess may mimic primary or secondary carcinoma of the liver on contrast-enhanced computed tomography (CECT). The present study was to explore the usefulness of the analysis of multislice-based texture acquired from CECT in the differentiation between pyogenic hepatic abscesses and malignant mimickers. METHODS: This retrospective study included 25 abscesses in 20 patients and 33 tumors in 26 subjects who underwent CECT. To make comparison, we also enrolled 19 patients with hepatic single simple cyst. The images from CECT were analyzed using a Laplacian of Gaussian band-pass filter (5 filter levels with sigma weighting ranging from 1.0 to 2.5). We also quantified the uniformity, entropy, kurtosis and skewness of the multislice-based texture at different sigma weightings. Statistical significance for these parameters was tested with one-way ANOVA followed by Tukey honestly significant difference (HSD) test. Diagnostic performance was evaluated using the receiver operating characteristic (ROC) curve analysis. RESULTS: There were significant differences in entropy and uniformity at all sigma weightings (P<0.001) among hepatic abscesses, malignant mimickers and simple cysts. The significant difference in kurtosis and skewness was shown at sigma 1.8 and 2.0 weightings (P=0.002-0.006). Tukey HSD test showed that the abscesses had a significantly higher entropy and lower uniformity compared with malignant mimickers (P=0.000-0.004). Entropy (at a sigma 2.0 weighting) had the largest area under the ROC curve (0.888) in differentiating abscesses from malignant mimickers, with a sensitivity of 81.8% and a specificity of 88.0% when the cutoff value was set to 3.64. CONCLUSION: Multislice-based texture analysis may be useful for differentiating pyogenic hepatic abscesses from malignant mimickers.

Randomized comparison of long and short vascular sheaths in reduction of the operator radiation exposure during uterine artery embolization.

OBJECTIVE: To introduce a method in which a long sheath is used instead of the traditional short sheath, to reduce the radiation exposure of operators in uterine artery embolization (UAE). METHODS: 52 patients undergoing UAE were randomly divided into two groups before the procedure: an 11-cm short sheath was used in Group A (n = 25), and a 45-cm-long sheath was used in Group B (n = 27); the 45-cm-long sheath was only partly inserted such that the hub of the sheath was approximately 34 cm caudal to the groin puncture site. All the procedures were standard bilateral UAE operations through unilateral approach. The other parameters of the two groups were kept the same, including the fluoroscopy conditions and the pelvic radiation field size. The thermoluminescent personal dosemeters were attached to the left wrist and left outer side of the thyroid collar of the operator during each operation. The radiation exposure of the operator, procedure duration and fluoroscopy time of each procedure were recorded. Statistical analysis was performed using independent samples t-test. RESULTS: The radiation exposure of both the left hand and thyroid of the operator was significantly reduced with the long sheath compared with the short sheath (89.5 ± 7.2 µGy vs 186.7 ± 12.6 µGy, p < 0.001, and 54.1 ± 5.5 µGy vs 63.9 ± 7.4 µGy, p < 0.001, respectively). No significant differences were found in the procedure duration and fluoroscopy time between the two groups (p > 0.1). CONCLUSION: Using a long sheath in UAE could significantly reduce the radiation exposure to the interventionists without extending the procedure duration or fluoroscopy time. ADVANCES IN KNOWLEDGE: For the first time, we introduce a simple and convenient method to reduce the radiation exposure of the operator in the UAE procedure.

Histogram analysis of apparent diffusion coefficient at 3.0 T in urinary bladder lesions: correlation with pathologic findings.

RATIONALE AND OBJECTIVES: To investigate the potential value of histogram analysis of apparent diffusion coefficient (ADC) obtained at standard (700 s/mm(2)) and high (1500 s/mm(2)) b values on a 3.0-T scanner in the differentiation of bladder cancer from benign lesions and in assessing bladder tumors of different pathologic T stages and to evaluate the diagnostic performance of ADC-based histogram parameters. MATERIALS AND METHODS: In all, 52 patients with bladder lesions, including benign lesions (n = 7) and malignant tumors (n = 45; T1 stage or less, 23; T2 stage, 7; T3 stage, 8; and T4 stage, 7), were retrospectively evaluated. Magnetic resonance examination at 3.0 T and diffusion-weighted imaging were performed. ADC maps were obtained at two b values (b = 700 and 1500 s/mm(2); ie, ADC-700 and ADC-1500). Parameters of histogram analysis included mean, kurtosis, skewness, and entropy. The correlations between these parameters and pathologic results were revealed. Receiver operating characteristic (ROC) curves were generated to determine the diagnostic value of histogram parameters. RESULTS: Significant differences were found in mean ADC-700, mean ADC-1500, skewness ADC-1500, and kurtosis ADC-1500 between bladder cancer and benign lesions (P = .002-.032). There were also significant differences in mean ADC-700, mean ADC-1500, and kurtosis ADC-1500 among bladder tumors of different pathologic T stages (P = .000-.046). No significant differences were observed in other parameters. Mean ADC-1500 and kurtosis ADC-1500 were significantly correlated with T stage, respectively (ρ = -0.614, P < .001; ρ = 0.374, P = .011). ROC analysis showed that the combination of mean ADC-1500 and kurtosis ADC-1500 has the maximal area under the ROC curve (AUC, 0.894; P < .001) in the differentiation of benign lesions and malignant tumors, with a sensitivity of 77.78% and specificity of 100%. AUCs for differentiating low- and high-stage tumors were 0.840 for mean ADC-1500 (P < .001) and 0.696 for kurtosis ADC-1500 (P = .015). CONCLUSIONS: Histogram analysis of ADC-1500 at 3.0 T can be useful in evaluation of bladder lesions. A combination of mean ADC-1500 and kurtosis ADC-1500 may be more beneficial in the differentiation of benign and malignant lesions. Mean ADC-1500 was the most promising parameter for differentiating low- from high-stage bladder cancer.

Entropy of T2-weighted imaging combined with apparent diffusion coefficient in prediction of uterine leiomyoma volume response after uterine artery embolization.

RATIONALE AND OBJECTIVES: To determine the potential value of entropy of T2-weighted imaging combined with apparent diffusion coefficient (ADC) before uterine artery embolization (UAE) for prediction of uterine leiomyoma volume reduction (VR) after UAE. MATERIALS AND METHODS: In this prospective study, 11 patients with uterine leiomyomas who underwent pelvic magnetic resonance imaging including diffusion-weighted imaging before and 6 months after UAE were included. A total number of 16 leiomyomas larger than 2 cm in diameter were evaluated. The volume of each leiomyoma before and after UAE was determined, and the percentage change in volume was calculated. Entropy of T2-weighted imaging and ADC before UAE were assessed. Pearson correction coefficients were calculated between leiomyoma VR after UAE and age, leiomyoma volume, ADC, and entropy, respectively. Multiple regression analysis was performed to investigate the parameters that determine the VR after UAE. Receiver operating characteristic curve analysis was used to determine the sensitivity and specificity of ADC, entropy and the combination of ADC and entropy for predicting volume response. RESULTS: The mean leiomyoma VR was 58.9% (range 25.8%-95.0%) in the 6-month follow-up. The mean ADC of leiomyomas was 1.37 × 10(-3) mm(2)/s (range 1.05 × 10(-3)-2.32 × 10(-3) mm(2)/s) and the mean entropy of T2-weighted imaging was 5.36 (range 4.62-5.91) before UAE. ADC and entropy were significantly correlated with leiomyoma VR, respectively (r = 0.61, P = .012; r = 0.73, P = .001). On multiple regression analysis, a combination of ADC and entropy constituted the best model for determining leiomyoma VR using Akaike information criterion. For predicting ≥50% VR, the optimal cutoff value of ADC was 1.39 × 10(-3) mm(2)/s (sensitivity 45.5%, specificity 80.0%) and the optimal cutoff value of entropy was 5.15 (sensitivity 90.9%, specificity 60.0%). The combination of ADC and entropy (area under the curve [AUC] 0.86) provided better classification accuracy than ADC or entropy alone (AUC 0.69 and 0.82, respectively). CONCLUSIONS: Pre-UAE entropy of T2-weighted imaging and ADC of leiomyomas were significantly correlated with the leiomyoma VR 6 months after embolization. Higher entropy and higher ADC may be related to greater leiomyoma VR after UAE. A combination of entropy and ADC may have predictive value for leiomyoma VR after UAE.