Sungmin Woo

Histogram analysis of apparent diffusion coefficient map of diffusion-weighted MRI in endometrial cancer: a preliminary correlation study with histological grade.

Background Until now, several investigators have explored the value of diffusion-weighted magnetic resonance imaging (DWI) for the preoperative tumor grading of endometrial cancer. However, the diagnostic value of DWI with quantitative analysis of apparent diffusion coefficient (ADC) has been controversial. Purpose To explore the role of histogram analysis of ADC maps based on entire tumor volume in determining the grade of endometrial cancer. Material and Methods This study was IRB-approved with waiver of informed consent. Thirty-three patients with endometrial cancer underwent DWI (bu2009=u20090, 600, 1000u2009s/mm2), and corresponding ADC maps were acquired. Regions of interest (ROIs) were drawn on all slices of the ADC map in which the tumor was visualized including areas of necrosis to derive volume-based histographic ADC data. Histogram parameters (5th–95th percentiles, mean, standard deviation, skewness, kurtosis) were correlated with histological grade using one-way ANOVA with Tukey-Kramer test for post hoc comparisons, and were compared between high (grade 3) and low (grades 1/2) grade using Student t-test. ROC curve analysis was performed to determine the optimum threshold value for each parameter, and their corresponding sensitivity and specificity. Results The standard deviation, quartile, 75th, 90th, and 95th percentiles of ADC showed significant differences between grades (Pu2009≤u20090.03 for all) and between high and low grades (Pu2009≤u20090.024 for all). There were no significant correlations between tumor grade and other parameters. ROC curve analysis yielded sensitivities and specificities of 75% and 96%, 62.5% and 92%, 100% and 52%, 100% and 72%, and 100% and 88%, using standard deviation, quartile, 75th, 90th, and 95th percentiles for determining high grade with corresponding areas under the curve (AUCs) of 0.787, 0.792, 0.765, 0.880, and 0.925, respectively. Conclusion Histogram analysis of ADC maps based on entire tumor volume can be useful for predicting the histological grade of endometrial cancer. The 90th and 95th percentiles of ADC were the most promising parameters for differentiating high from low grade.

Diagnostic Performance of Prostate Imaging Reporting and Data System Version 2 for Detection of Prostate Cancer: A Systematic Review and Diagnostic Meta-analysis

CONTEXTnIn 2015, the updated Prostate Imaging Reporting and Data System version 2 (PI-RADSv2) for the detection of prostate cancer (PCa) was established. Since then, several studies assessing the value of PI-RADSv2 have been published.nnnOBJECTIVEnTo review the diagnostic performance of PI-RADSv2 for the detection of PCa.nnnEVIDENCE ACQUISITIONnMEDLINE and EMBASE databases were searched up to December 7, 2016. We included diagnostic accuracy studies that used PI-RADSv2 for PCa detection, using prostatectomy or biopsy as the reference standard. The methodological quality was assessed by two independent reviewers using the Quality Assessment of Diagnostic Accuracy Studies-2 tool. Sensitivity and specificity of all studies were calculated. Results were pooled and plotted in a hierarchical summary receiver operating characteristic plot with further exploration using meta-regression and multiple subgroup analyses. Head-to-head comparison between PI-RADSv1 and PI-RADSv2 was performed for available studies.nnnEVIDENCE SYNTHESISnTwenty-one studies (3857 patients) were included. The pooled sensitivity was 0.89 (95% confidence interval [CI] 0.86-0.92) with specificity of 0.73 (95% CI 0.60-0.83) for PCa detection. Proportion of patients with PCa, magnetic field strength, and reference standard were significant factors affecting heterogeneity (p<0.01). Multiple subgroup analyses showed consistent results. In six studies performing head-to-head comparison, PI-RADSv2 demonstrated higher pooled sensitivity of 0.95 (95% CI 0.85-0.98) compared with 0.88 (95% CI 0.80-0.93) for PI-RADSv1 (p=0.04). However, the pooled specificity was not significantly different (0.73 [95% CI 0.47-0.89] vs 0.75 [95% CI 0.36-0.94], respectively; p=0.90).nnnCONCLUSIONSnPI-RADSv2 shows good performance for the detection of PCa. PI-RADSv2 has higher pooled sensitivity than PI-RADSv1 without significantly different specificity.nnnPATIENT SUMMARYnWe reviewed all previous studies using Prostate Imaging Reporting and Data System version 2 (PI-RADSv2) for prostate cancer detection. We found that the updated PI-RADSv2 shows significant improvement compared with the original PI-RADSv1.

Liver Abscess After Transarterial Chemoembolization in Patients With Bilioenteric Anastomosis: Frequency and Risk Factors.

OBJECTIVEnThe purpose of this study was to clarify the frequency of and risk factors for liver abscess formation after transarterial chemoembolization (TACE) in patients with hepatocellular carcinoma or metastatic hepatic tumors after undergoing bilioenteric anastomosis.nnnMATERIALS AND METHODSnFrom January 1996 to June 2012, 25 patients (21 men, four women; age range, 34-74 years) with hepatocellular carcinoma (n = 12) or metastatic hepatic tumors (n = 13) with an underlying bilioenteric anastomosis underwent 65 TACE procedures. The incidence of liver abscess, predisposing factors (diabetes, Child-Pugh class, leukopenia, tumor number, tumor size, tumor burden, tumor type, portal vein thrombus, lipiodol dose, particulate embolization, embolization selectivity, oily portogram, antibiotic prophylaxis, and occurrence of liver abscess at initial TACE), and clinical outcome were evaluated. Statistical analysis for relations between liver abscess and predisposing factors was performed by Fisher exact test and linear-by-linear association.nnnRESULTSnLiver abscess developed after 17 of 65 (26.2%) TACE procedures performed on 12 of 25 (48%) patients. Two patients died of progression of liver abscess into sepsis. Univariate and multivariate analyses showed that leukopenia (p = 0.029), occurrence of liver abscess at initial TACE (p = 0.082), and particulate embolization or oily portogram (grade 2) (p = 0.001) were associated with a higher incidence of liver abscess.nnnCONCLUSIONnThe incidence of liver abscess was high among patients with bilioenteric anastomoses who underwent TACE. Leukopenia, occurrence of liver abscess at initial session of TACE, and particulate embolization or oily portogram (grade 2) were associated with the development of liver abscess.

Bronchial Artery Embolization to Control Hemoptysis: Comparison of N-Butyl-2-Cyanoacrylate and Polyvinyl Alcohol Particles

PURPOSEnTo retrospectively compare safety and effectiveness of embolic agents polyvinyl alcohol (PVA) particles versus n-butyl-2-cyanoacrylate (NBCA) for bronchial artery embolization (BAE) for control of hemoptysis.nnnMATERIALS AND METHODSnInstitutional review board approved this retrospective study; informed consent was waived. From January 2005 to December 2008, 406 patients (242 men, 164 women; age range, 6-92 years) with major hemoptysis underwent BAE by using PVA particles (n = 293) or NBCA (n = 113). Technical and clinical success, complications, hemoptysis-free survival rates, and causes of recurrent hemoptysis were compared between PVA and NBCA groups. The differences in hemoptysis-free survival rates were assessed between subgroups stratified to underlying diseases. The predictive factor for recurrent hemoptysis was identified with Cox proportional hazard regression model.nnnRESULTSnTechnical success was achieved in 93.9% (275 of 293) and 96.5% (109 of 113) of patients for PVA and NBCA, respectively (P = .463); clinical success was achieved in 92.2% (270 of 293) and 96.5% (109 of 113) of patients for PVA and NBCA, respectively (P = .180). Overall and major complication rates were not statistically different (overall complication rates: 34.1% for PVA, 31.0% for NBCA; P = .56; major complication rates: 0.3% for PVA, 0% for NBCA; P > .999). The 1-, 3-, and 5-year hemoptysis-free survival rates were, respectively, 77%, 68%, and 66% for PVA and 88%, 85%, and 83% for NBCA (P = .01). Recanalization of previously embolized vessels was more frequent in PVA group (21.5%) than in NBCA group (1.8%; P < .001). NBCA group showed hemoptysis-free survival rates superior to PVA group in patients with bronchiectasis (P = .016). PVA (P = .050) and aspergilloma (P < .001) were predictive factors for recurrent hemoptysis.nnnCONCLUSIONnBAE with NBCA provided higher hemoptysis-free survival rates compared with PVA particles without increasing complication rates. This improvement was evident in patients with bronchiectasis and was caused by more durable embolic effect than PVA particles.nnnSUPPLEMENTAL MATERIALnhttp://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.13130046/-/DC1.

Extracapsular Extension in Prostate Cancer: Added Value of Diffusion-Weighted MRI in Patients With Equivocal Findings on T2-Weighted Imaging

OBJECTIVE. The objective of our study was to evaluate diffusion-weighted imaging (DWI) and T2-weighted imaging for predicting extracapsular extension (ECE) in patients with prostate cancer. MATERIALS AND METHODS. One hundred seventeen patients underwent preoperative 3-T MRI and radical prostatectomy. Two radiologists evaluated ECE with T2-weighted imaging based on the Prostate Imaging Reporting and Data System (PI-RADS). Then, the apparent diffusion coefficient (ADC) of the tumor calculated from two b values (0, 1000 s/mm(2)) was measured. Interreader agreement of T2-weighted imaging scores was assessed with weighted kappa statistics. We compared T2-weighted imaging scores and ADC values between patients with ECE and those without ECE using the unpaired Student t test and evaluated their association with ECE using logistic regression analyses and ROC curves incorporating prostate-specific antigen value, Gleason score, clinical stage, and greatest percentage involved core length. The ADC values were also tested for differences between patients with ECE and those without ECE in subgroups stratified by the T2-weighted imaging criteria shown to have a high specificity for ECE. RESULTS. Fifty (42.7%) patients had ECE. There was substantial agreement for T2-weighted imaging scores (κ = 0.613). T2-weighted imaging scores and ADCs were significantly different in patients with ECE and those without ECE (p < 0.001). Multivariate analysis showed that the greatest percentage involved core length, T2-weighted imaging score, and ADC (p < 0.05) were independently predictive of ECE. The AUCs for these variables (range, 0.733-0.770) were not significantly different except for the AUC for clinical stage (0.552). The use of a high specificity (92.5%) setting for ECE divided the patients into the following groups: patients with a T2-weighted imaging score of ≥ 4 (n = 20) and patients with a T2-weighted imaging score of < 4 (n = 97). In patients with a T2-weighted imaging score of ≥ 4, the ADC was not significantly different between patients with ECE and those without ECE (p = 0.555). However, among patients with a T2-weighted imaging score of ≤ 3, the ADC value was significantly lower in patients with ECE (mean ± SD, 0.794 ± 0.116) than in those without ECE (1.027 ± 0.339) (p < 0.001). CONCLUSION. T2-weighted imaging scores and ADCs were independently associated with ECE, and the ADC had incremental value in patients without a high suspicion of ECE on T2-weighted imaging.

Angiomyolipoma with minimal fat and non-clear cell renal cell carcinoma: differentiation on MDCT using classification and regression tree analysis-based algorithm

Background Differentiation between angiomyolipoma with minimal fat (AMLmf) and non-clear cell renal cell carcinoma (nccRCC) may be difficult owing to lack of macroscopic fat in AMLmf. However, the differential points between AMLmf and nccRCC has not been well established in the literature. Purpose To evaluate quantitative triphasic multidetector computed tomography (MDCT) features that differentiate between small AMLmf and nccRCC, and to integrate them to develop a simple and easy diagnostic algorithm. Material and Methods This study was approved by the Institutional Review Board; informed consent was waived. Triphasic MDCT images of pathologically-proven AMLmfs (nu2009=u200924) and nccRCCs (nu2009=u200955) of 79 patients were retrospectively evaluated. Age, sex, size, long-to-short axis ratio (LSR), attenuation and enhancement degree in all phases, unenhanced tumor-kidney attenuation difference (UTKAD) in Hounsfield units (HU) were compared with Chi-square analysis, independent-samples t-test, and receiver-operating characteristic (ROC) curves. A criterion was formulated with classification and regression tree analysis (CART). Thereafter, CART-based algorithm was tested with additional interpretations from two radiologists. Intra- and inter-observer variability was analyzed with Bland-Altman analysis. Results LSR was greater in AMLmf than nccRCC (Pu2009<u20090.001). AMLmf showed higher attenuation (all phases), CMP enhancement, and wash-out than nccRCC (Pu2009≤u20090.001). UTKAD was greater in AMLmf than nccRCC (Pu2009<u20090.001). ROC curve analysis yielded area under the curves of 0.936, 0.888, and 0.853 using UTKAD, unenhanced attenuation, and LSR. CART-based algorithm (UTKAD >7.5u2009HU, LSRu2009>u20091.23) predicted AMLmf with sensitivity, specificity, PPV, and NPV of 87.5%, 96.4%, 91.3%, and 94.6%. Mean intra- and inter-observer difference was –0.1/0.03u2009HU and −1.0/0.09u2009HU for UTKAD/LSR, respectively. These interpretations changed the final diagnosis in 1.3% (1/79) and 5.1% (4/79) patients for radiologists 1 and 2. Conclusion Triphasic MDCT was useful for differentiating AMLmf and nccRCC. CART-based algorithm using UTKADu2009>u20097.5 and LSRu2009>u20091.23 was simple and accurate in predicting AMLmf.

Comparison of Segmental Enhancement Inversion on Biphasic MDCT Between Small Renal Oncocytomas and Chromophobe Renal Cell Carcinomas

OBJECTIVEnThe purpose of this article is to assess the usefulness of segmental enhancement inversion on biphasic MDCT in differentiating small (<4 cm) renal oncocytomas from chromophobe renal cell carcinomas (CRCCs).nnnMATERIALS AND METHODSnEighty-two patients (40 men and 42 women) with a mean (±SD) age of 54±12 years (range, 21-75 years) with 27 renal oncocytomas and 55 CRCCs diagnosed by surgery who underwent contrast-enhanced biphasic CT between January 2000 and December 2011 were included. CT scans were interpreted by two radiologists who were blinded to the pathologic findings. The tumors were evaluated for size and segmental enhancement inversion. After independent evaluation, a consensus was reached by measuring the attenuation. Pathologic analysis determined the presence of fibrous septa, cystic change, hemorrhage, and necrosis. The Fisher exact test was used to evaluate the relationship between segmental enhancement inversion, tumor type, and specific pathologic changes. Interobserver concordance was evaluated with kappa statistics.nnnRESULTSnThere were no significant differences in size between renal oncocytomas and CRCCs (p=0.458). Segmental enhancement inversion was present in 23, 20, and 21 (25.6%) of the 82 tumors according to reader 1, reader 2, and the consensus, respectively. The agreement was almost perfect (κ=0.843; p<0.001). Segmental enhancement inversion was more common in renal oncocytomas (63% [17/27]) than in CRCCs (7.3% [4/55]; p<0.001). There were no significant relationships between the four pathologic changes and tumor type or segmental enhancement inversion (p=0.351 and p=0.126, respectively).nnnCONCLUSIONnOur study findings suggest that segmental enhancement inversion on biphasic MDCT may be useful in differentiating small renal oncocytomas from CRCCs.

Angiomyolipoma with minimal fat: differentiation of morphological and enhancement features from renal cell carcinoma at CT imaging.

Background Angiomyolipoma (AML) with minimal fat may mimic renal cell carcinoma (RCC) and is difficult to distinguish from RCC with imaging studies alone. Precise diagnostic strategies have been explored to discern AML with minimal fat from RCC. Purpose To compare the morphological and enhancement features of AML with minimal fat with those of size-matched RCC on computed tomography (CT). Material and Methods Our study included 143 pathologically proved renal tumors (29 AML with minimal fat: mean diameter, 2.5u2009cm; range, 1.2–4u2009cm; 114 RCC: mean diameter, 2.8u2009cm; range, 1.3–4u2009cm). All patients underwent biphasic helical CTs. Two radiologists retrospectively evaluated the morphological (i.e. non-round and round appearances, with or without capsule) and enhancement features (i.e., wash-out, gradual, or prolonged). For the parameters that had statistically significance between the two groups, we calculated the positive and negative predictive values by using the univariate χ2 test. Pu2009<u20090.05 indicated a significant difference. Results AML with minimal fat showed a non-round appearance without a capsule (nu2009=u200924, 83%) and prolonged enhancement (nu2009=u200920, 69%). The positive and negative predictive values of the non-round appearance without capsule for differentiating AML with minimal fat from RCC were 82.8% and 95.6%, respectively. The positive and negative predictive values of prolonged enhancement were 62.5% and 90.8%, respectively. These features were valuable predictors for AML with minimal fat from RCC. Conclusion CT images with non-round shape without capsule and prolonged enhancements may be used to differentiate AML with minimal fat from RCC.

Preoperative Evaluation of Prostate Cancer Aggressiveness: Using ADC and ADC Ratio in Determining Gleason Score

OBJECTIVEnThe objective of our study was to evaluate apparent diffusion coefficient (ADC) and various ADC ratios in determining aggressiveness of prostate cancer.nnnMATERIALS AND METHODSnOne hundred sixty-five patients with biopsy-proven prostate cancer underwent 3-T MRI followed by radical prostatectomy. ADC and ADC ratios were calculated using the peripheral zone, transition zone, same zone as the tumor, and urinary bladder as references. ADC and ADC ratios were correlated with Gleason score using the Spearman correlation coefficient (ρ) and were compared between low-grade (Gleason score = 6) and high-grade (Gleason score ≥ 7) prostate cancer using the unpaired t test. ROC curves were used to compare diagnostic accuracies of ADC and ADC ratios in determining high-grade prostate cancer.nnnRESULTSnFifty-six (33.9%) and 109 (66.1%) patients had low- and high-grade prostate cancer, respectively. ADC (ρ = -0.476) and all ADC ratios (ρ = -0.397, -0.412, -0.381, and -0.474, respectively) correlated significantly with Gleason score (p < 0.001) and were significantly lower in patients with high-grade prostate cancer (p < 0.001). For predicting high-grade prostate cancer, tumor ADC and tumor-to-urinary bladder ADC ratio showed the highest AUC (0.794 and 0.790, respectively) but without statistically significant difference (p = 0.803). AUC of tumor ADC (0.794) was statistically significantly higher than those of the tumor-to-peripheral zone and tumor-to-transition zone ADC ratios (0.746, p = 0.039; 0.751, p = 0.027; respectively). AUC of tumor ADC was not statistically significantly higher than that of the tumor-to-tumor zone ADC ratio (0.763, p = 0.193). AUC calculated using the tumor-to-urinary bladder ADC ratio was statistically significantly higher than that using the tumor-to-transition zone ADC ratio (p = 0.028) and marginally higher than that from tumor-to-peripheral zone ADC ratio (p = 0.080). Otherwise, no significant differences were seen in the AUCs (p = 0.193-0.828).nnnCONCLUSIONnBoth ADC and various ADC ratios correlated significantly with Gleason score and were significant predictors of high-grade prostate cancer. However, no benefit was found in using ADC ratio over ADC.

PI-RADS version 2 for prediction of pathological downgrading after radical prostatectomy: a preliminary study in patients with biopsy-proven Gleason Score 7 (3+4) prostate cancer

AbstractObjectivesTo evaluate PI-RADSv2 for predicting pathological downgrading after radical prostatectomy (RP) in patients with biopsy-proven Gleason score (GS) 7(3+4) PC.MethodsA total of 105 patients with biopsy-proven GS 7(3+4) PC who underwent multiparametric prostate MRI followed by RP were included. Two radiologists assigned PI-RADSv2 scores for each patient. Preoperative clinicopathological variables and PI-RADSv2 scores were compared between patients with and without downgrading after RP using the Wilcoxon rank sum test or Fisher’s exact test. Logistic regression analyses with Firth’s bias correction were performed to assess their association with downgrading.ResultsPathological downgrading was identified in ten (9.5xa0%) patients. Prostate-specific antigen (PSA), PSA density, percentage of cores with GS 7(3+4), and greatest percentage of core length (GPCL) with GS 7(3+4) were significantly lower in patients with downgrading (pu2009=u20090.002-0.037). There was no significant difference in age and clinical stage (pu2009=u20090.537-0.755). PI-RADSv2 scores were significantly lower in patients with downgrading (3.8 versus 4.4, pu2009=u20090.012). At univariate logistic regression analysis, PSA, PSA density, and PI-RADSv2 scores were significant predictors of downgrading (pu2009=u20090.003-0.022). Multivariate analysis revealed only PSA density and PI-RADSv2 scores as independent predictors of downgrading (pu2009=u20090.014-0.042).ConclusionsThe PI-RADSv2 scoring system was an independent predictor of pathological downgrading after RP in patients with biopsy-proven GS 7(3+4) PC.Key points• PI-RADSv2 was an independent predictor of downgrading in biopsy-proven GS 7(3+4) PCn • PSA density was also an independent predictor of downgradingn • MRI may assist in identifying AS candidates in biopsy-proven GS 7(3+4) PC patients