Sang Youn Kim

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.

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.

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.

Shear wave elastography assessment in the prostate: an intraobserver reproducibility study☆

PURPOSEnTo assess the intraobserver reproducibility of shear wave elastography (SWE) in the prostate.nnnMATERIALS AND METHODSnThis study was institutional review board approved with waiver of informed consent. Eighty men (mean age, 66.2±9.2years) with suspected prostate cancer underwent SWE. Young modulus (kPa) was measured at 24 locations in the prostate (superficial and deep locations in paramedian and lateral aspects at the base, mid-gland, and apex levels). The intraobserver reproducibility of two repeated measurements was determined using intraclass correlation coefficients (ICC) and was compared among measurement location, prostate volume, age, and prostate-specific antigen level.nnnRESULTSnThe overall intraobserver reproducibility was excellent (ICC=0.876). In addition, intraobserver reproducibility was excellent for all specified subgroups according to location, prostate volume, and clinical variables (ICC=0.826-0.917). With regard to location, SWE measurements showed substantially higher ICC values in the mid-gland than in the base and apex, in the paramedian prostate than in the lateral prostate, and in superficial locations than in deeper locations. No substantial differences in ICC values were observed according to the prostate volume and clinical variables.nnnCONCLUSIONnIntraobserver reproducibility of SWE measurements in the prostate gland was excellent. There was variability in the intraobserver reproducibility according to location within the prostate, and the operator should be aware of this and take extra caution when performing SWE in these areas.

Periprostatic Fat Thickness on MRI: Correlation With Gleason Score in Prostate Cancer

OBJECTIVEnThe purpose of this study was to retrospectively evaluate the relationship between periprostatic fat thickness on MRI and Gleason score of prostate cancer using radical prostatectomy as the reference standard.nnnMATERIALS AND METHODSnThis study included 190 patients (mean age [± SD], 66.9 ± 7.0 years) who underwent MRI before radical prostatectomy. Two radiologists measured the subcutaneous and periprostatic fat thickness on midsagittal T2-weighted MR images as the shortest perpendicular distance from the pubic symphysis to the skin and prostate, respectively. Subcutaneous and periprostatic fat along with age, height, weight, body mass index, and prostate-specific antigen (PSA) were correlated with Gleason score by using Pearson (r) or Spearman (ρ) correlation coefficients and compared between low- (Gleason score = 6) and high- (≥ 7) grade prostate cancer by using univariate and multivariate logistic regression analyses.nnnRESULTSnThe mean subcutaneous and periprostatic fat thicknesses were 24.0 ± 8.4 mm and 5.0 ± 2.0 mm, respectively. The Gleason score was significantly correlated with age (ρ = 0.181, p = 0.012), PSA (ρ = 0.345, p < 0.001), and periprostatic fat thickness (ρ = 0.228, p = 0.002). Multivariate analysis revealed that age, height, PSA level, and periprostatic fat thickness (odds ratio, 1.331; 95% CI, 1.063-1.666) were independently predictive of high-grade (p ≤ 0.013) disease.nnnCONCLUSIONnPeriprostatic fat thickness on MRI showed a mild to modest but significant correlation with Gleason score of prostate cancer with radical prostatectomy as the reference standard and was an independent predictive factor for high-grade prostate cancer.

A systematic approach to the magnetic resonance imaging-based differential diagnosis of congenital Müllerian duct anomalies and their mimics

Müllerian duct anomalies (MDAs) represent a wide spectrum of developmental abnormalities related to various gynecologic and obstetric complications, including primary amenorrhea, infertility, and endometriosis. The use of diverse imaging modalities, in conjunction with clinical information, provide important clues to the diagnosis of MDAs. Diagnostic imaging work-up for MDAs often begins with hysterosalpingography (HSG) and/or ultrasonography (US). Although HSG and/or US may suffice to detect the presence of a uterine abnormality, magnetic resonance (MR) imaging is generally needed to classify the abnormality into a specific MDA category. MR imaging has been gaining in popularity for use in evaluating MDAs, by virtue of its noninvasiveness, lack of ionizing radiation, and capability for multiplanar imaging and soft tissue characterization. Abnormalities in the external uterine fundal contour are readily recognized with MR imaging, allowing for clear differentiation between a fusion anomaly, such as a uterus didelphys or a bicornuate uterus, and a resorption anomaly, such as a septate uterus. Furthermore, MR imaging enables clear depiction of a rudimentary uterine horn in a unicornuate uterus. Accurate differential diagnosis of MDAs on the basis of their characteristic MR imaging findings is crucial, because the rates of gynecologic and obstetric complications vary considerably among MDAs. The diagnostic accuracy may be enhanced by adopting a systematic approach to MR imaging-based differential diagnosis.

Segmental Enhancement Inversion of Small Renal Oncocytoma: Differences in Prevalence According to Tumor Size

OBJECTIVEnThe purpose of this study was to retrospectively assess the prevalence of segmental enhancement inversion of small renal oncocytomas according to tumor size.nnnMATERIALS AND METHODSnThirty-three patients (19 men, 14 women; mean age, 61 years; range, 40-74 years) with 33 oncocytomas diagnosed at surgical resection who had undergone contrast-enhanced biphasic CT between January 2000 and December 2011 were included. CT scans were analyzed by two radiologists blinded to the specifics of the pathology report for size, presence of segmental enhancement inversion, enhancement pattern, and homogeneity. Segmental enhancement inversion was present when a renal mass was divided into two differently enhanced segments in the corticomedullary phase (30-40 seconds after contrast injection) with the degree of enhancement reversed in the nephrographic phase (120-180 seconds after contrast injection). The masses were further assessed for fibrous septa, cystic change, hemorrhage, and necrosis. For statistical analysis, the Pearson chi-square test and linear regression were used to evaluate the relation between the prevalence of segmental enhancement inversion and tumor size or pathologic changes.nnnRESULTSnThe mean diameter of 33 renal oncocytomas was 2.65 cm (range, 0.8-4.8 cm). There was no significant linear trend according to size (p = 0.762), although segmental enhancement inversion was significantly (p = 0.006) more common (10/12) in tumors measuring 1.5-2.9 cm. Pathologic change was present in 14 oncocytomas. There was no significant linear trend according to size (p = 0.068), but 2.5-cm and larger tumors had a significantly higher prevalence (57.9%) (p = 0.036). Segmental enhancement inversion was more common (13/19) in tumors without pathologic change (p = 0.024).nnnCONCLUSIONnSegmental enhancement inversion was a characteristic finding in our series of small renal oncocytomas and was more common in tumors measuring 1.5-2.9 cm. Pathologic changes such as central scar were more common in oncocytomas larger than 2.5 cm and may be related to the low occurrence of segmental enhancement inversion.

Magnetic Resonance Evaluation of Müllerian Remnants in Mayer-Rokitansky-Küster-Hauser Syndrome

Objective To analyze magnetic resonance imaging (MRI) findings of Müllerian remnants in young females clinically suspected of Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome in a primary amenorrhea workup. Materials and Methods Fifteen young females underwent multiplanar T2- and transverse T1-weighted MRI at either a 1.5T or 3.0T MR imager. Two gynecologic radiologists reached consensus decisions for the evaluation of Müllerian remnants, vagina, ovaries, and associated findings. Results All cases had bilateral uterine buds in the pelvic cavity, with unilateral cavitation in two cases. The buds had an average long-axis diameter of 2.64 ± 0.65 cm. In all cases, bilateral buds were connected with fibrous band-like structures. In 13 cases, the band-like structures converged at the midline or a paramedian triangular soft tissue lying above the bladder dome. The lower one-third of the vagina was identified in 14 cases. Fourteen cases showed bilateral normal ovaries near the uterine buds. One unilateral pelvic kidney, one unilateral renal agenesis, one mild scoliosis, and three lumbar sacralization cases were found as associated findings. Conclusion Typical Müllerian remnants in MRKH syndrome consist of bilateral uterine buds connected by the fibrous band-like structures, which converge at the midline triangular soft tissue lying above the bladder dome.

MDCT Findings of Renal Cell Carcinoma Associated With Xp11.2 Translocation and TFE3 Gene Fusion and Papillary Renal Cell Carcinoma

OBJECTIVE. The purpose of this study was to compare the MDCT features of renal cell carcinoma (RCC) associated with Xp11.2 translocation and TFE3 gene fusion (Xp11 RCC) and papillary RCC. MATERIALS AND METHODS. The study included 19 and 39 patients with histologically proven Xp11 RCC and papillary RCC, respectively, who underwent multiphase renal MDCT before nephrectomy. CT findings were compared between Xp11 RCC and papillary RCC using the Student t test and chi-square test. Subgroup analyses of small (< 4 cm) renal masses for these features were performed. RESULTS. Patients with Xp11 RCC were younger (p < 0.001), and it was more prevalent in women (p = 0.007). Tumor size was greater in Xp11 RCC (p = 0.004) and more common in cystic change (p < 0.001). Calcification and unenhanced high-attenuating areas were more frequent in Xp11 RCC (p = 0.001 and 0.026, respectively). Xp11 RCCs were more prevalent in lymph node and distant metastasis (p < 0.001 and p = 0.031, respectively). Xp11 RCC and papillary RCC showed no significant difference in epicenter, margin, and venous and collecting duct invasion (p = 0.403-1.000). Although Xp11 RCC and papillary RCC had lower attenuation than the renal cortex on corticomedullary and early excretory phases (p < 0.001), only Xp11 RCCs were hyperattenuating to the cortex on the unenhanced phase (p < 0.001). Xp11 RCCs had significantly higher attenuation compared with papillary RCCs on all phases (p ≤ 0.02). Regarding small masses, cystic change, calcification, and lymph node metastasis were still more frequent in Xp11 RCCs (p ≤ 0.016). CONCLUSION. Greater size, more cystic change, calcification, high-attenuating areas on unenhanced imaging, and lymph node and distant metastasis were helpful for differentiating Xp11 RCC from papillary RCC.

Head-To-Head Comparison Between High- and Standard-b-Value DWI for Detecting Prostate Cancer: A Systematic Review and Meta-Analysis

OBJECTIVEnThe purpose of this study was to perform a head-to-head comparison between high-b-value (> 1000 s/mm2) and standard-b-value (800-1000 s/mm2) DWI regarding diagnostic performance in the detection of prostate cancer.nnnMATERIALS AND METHODSnThe MEDLINE and EMBASE databases were searched up to April 1, 2017. The analysis included diagnostic accuracy studies in which high- and standard-b-value DWI were used for prostate cancer detection with histopathologic examination as the reference standard. Methodologic quality was assessed with the revised Quality Assessment of Diagnostic Accuracy Studies tool. Sensitivity and specificity of all studies were calculated and were pooled and plotted in a hierarchic summary ROC plot. Meta-regression and multiple-subgroup analyses were performed to compare the diagnostic performances of high- and standard-b-value DWI.nnnRESULTSnEleven studies (789 patients) were included. High-b-value DWI had greater pooled sensitivity (0.80 [95% CI, 0.70-0.87]) (p = 0.03) and specificity (0.92 [95% CI, 0.87-0.95]) (p = 0.01) than standard-b-value DWI (sensitivity, 0.78 [95% CI, 0.66-0.86]); specificity, 0.87 [95% CI, 0.77-0.93] (p < 0.01). Multiple-subgroup analyses showed that specificity was consistently higher for high- than for standard-b-value DWI (p ≤ 0.05). Sensitivity was significantly higher for high- than for standard-b-value DWI only in the following subgroups: peripheral zone only, transition zone only, multiparametric protocol (DWI and T2-weighted imaging), visual assessment of DW images, and per-lesion analysis (p ≤ 0.04).nnnCONCLUSIONnIn a head-to-head comparison, high-b-value DWI had significantly better sensitivity and specificity for detection of prostate cancer than did standard-b-value DWI. Multiple-subgroup analyses showed that specificity was consistently superior for high-b-value DWI.