Hyun Moo Lee

Value of Diffusion-weighted Imaging for the Prediction of Prostate Cancer Location at 3t Using a Phased-array Coil: Preliminary Results

Objectives:To retrospectively evaluate the imaging quality of diffusion-weighted imaging (DWI), compare the apparent diffusion coefficient (ADC) values for malignant and benign tissues in the peripheral zone (PZ) and transition zone (TZ), and evaluate whether T2-weighted imaging (T2WI) with DWI could improve the prediction of prostate cancer location when compared with T2WI at 3T using a phased-array coil. Materials and Methods:Thirty-seven patients underwent T2WI and DWI before radical prostatectomy. The DWI technique with b = 0 and b = 1000 s/mm2 was used. ADC values were measured in benign and malignant tissues in the PZ or TZ. The prediction of prostate cancer location was evaluated in the PZ and TZ using T2WI and T2WI with DWI, respectively. Two readers in consensus recorded the presence of prostate cancer at magnetic resonance imaging and rated the imaging quality of DWI. Results:For the prediction of 68 prostate tumors, the overall sensitivity and positive predictive value of T2WI with DWI were 84% and 86%, whereas those of T2WI were 66% and 63%, respectively (P < 0.05). The mean ADC values of malignant and benign tissues in the PZ and TZ were 1.30 ± 0.26 and 1.96 ± 0.20, and 1.35 ± 0.24 and 1.75 ± 0.23 × 10−3mm2/s, respectively (P < 0.01). The overall imaging quality was satisfactory or better in 97% of patients. Conclusion:DWI is a feasible technique that can be used for the differentiation of malignant and benign tissues in the PZ and TZ. Additionally, T2WI with DWI is superior to T2WI alone for the prediction of prostate cancer location.

Diffusion-weighted imaging of the prostate at 3 T for differentiation of malignant and benign tissue in transition and peripheral zones: Preliminary results

Objective: To evaluate prospectively the use of apparent diffusion coefficients (ADCs) for the differentiation of malignant and benign tissue in the transition (TZ) and peripheral (PZ) zones of the prostate diffusion-weighted imaging (DWI) at 3 T magnetic resonance imaging (MRI) using a phased-array coil. Methods: The DWI at 3-T MRI was performed on a total of 35 patients before radical prostatectomy. A single-shot echo-planar imaging DWI technique with b = 0 and b = 1000 s/mm2 was used. The ADC values were measured in both benign and malignant tissues in the PZ and TZ using regions of interest. Differences between PZ and TZ ADC values were estimated using a paired Student t test. Presumed ADC cutoff values in the PZ and TZ for the diagnosis of cancer were assessed by receiver operating characteristic analysis. Results: The ADC values of malignant tissues were significantly lower than those of benign tissues in the PZ and TZ (P < 0.001; 1.32 ± 0.24 × 10−3 mm2/s vs 1.97 ± 0.25 × 10−3 mm2/s, and 1.37 ± 0.29 × 10−3 mm2/s vs 1.79 ± 0.19 × 10−3 mm2/s, respectively). For tumor diagnosis, cutoff values of 1.67 × 10−3 mm2/s (PZ) and 1.61 × 10−3 mm2/s (TZ) resulted in sensitivities and specificities of 94% and 91% and 90% and 84%, respectively. Conclusions: The DWI of the prostate at 3T MRI using a phased-array coil was useful for the differentiation of malignant and benign tissues in the TZ and PZ.

Comparison of phased-array 3.0-T and endorectal 1.5-T magnetic resonance imaging in the evaluation of local staging accuracy for prostate cancer.

Objective: To retrospectively evaluate local staging accuracy for prostate cancer at 3.0-T magnetic resonance imaging (MRI) by comparing with that at 1.5-T MRI. Methods: Two groups, each consisting of 54 patients, were included by matching for age, prostate specific antigen, and Gleason score. Before radical prostatectomy, 1 group underwent 3.0-T MRI using a phased-array coil, and the other 1.5-T MRI using an endorectal coil. T2-weighted MR images at 3.0 and 1.5 T were analyzed in consensus by 2 radiologists, and their staging accuracy was compared with histology. Artifact and overall image quality were compared at both 3.0 and 1.5 T. Results: Accuracy for T3 stage at 3.0 and 1.5 T were 72% (39/54) and 70% (38/54), respectively (P > 0.05). The 3.0-T MRI had a lower incidence of MR artifacts than the 1.5-T MRI (P < 0.05). However, overall imaging quality at both 3.0 and 1.5 T had no significant difference (P > 0.05). Conclusions: The 3.0-T phased-array MRI is equivalent to the 1.5-T endorectal MRI in evaluating local staging accuracy for prostate cancer without significant loss of imaging quality.

Body mass index and survival in patients with renal cell carcinoma: a clinical-based cohort and meta-analysis.

Growing evidence suggests that obesity, an established cause of renal cell cancer (RCC), may also be associated with a better prognosis. To evaluate the association between RCC survival and obesity, we analyzed a large cohort of patients with RCC and undertook a meta‐analysis of the published evidence. We collected clinical and pathologic data from 1,543 patients who underwent nephrectomy for RCC between 1994 and 2008 with complete follow‐up through 2008. Patients were grouped according to BMI (kg/m2): underweight <18.5, normal weight 18.5 to <23, overweight 23 to <25 and obese ≥25. We estimated survival using the Kaplan–Meier method and Cox proportional hazard models to examine the impact of BMI on overall survival (OS) and cancer‐specific survival (CSS) with adjustment for covariates. We performed a meta‐analysis of BMI and OS, CSS and recurrence‐free survival (RFS) from all relevant studies using a random‐effects model. The 5‐year CSS increased from 76.1% in the lowest to 92.7% in the highest BMI category. A multivariate analysis showed higher OS [hazard ratio (HR) = 0.45; 95% CI: 0.29–0.68) and CSS (HR = 0.47; 95% CI: 0.29–0.77] in obese patients than in normal weight patients. The meta‐analysis further corroborated that high BMI significantly improved OS (HR = 0.57; 95% CI: 0.43–0.76), CSS (HR = 0.59; 95% CI: 0.48–0.74) and RFS (HR = 0.49; 95% CI: 0.30–0.81). Our study shows that preoperative BMI is an independent prognostic indicator for survival among patients with RCC.

MRI Techniques for Prediction of Local Tumor Progression After High-Intensity Focused Ultrasonic Ablation of Prostate Cancer

OBJECTIVE The purpose of this study was to evaluate the diagnostic performance of dynamic contrast-enhanced MRI (DCE-MRI) and of T2-weighted MRI with diffusion-weighted imaging (DWI) for predicting local tumor progression after high-intensity focused ultrasonic ablation of localized prostate cancer. MATERIALS AND METHODS Twenty-seven patients who had increased levels of prostate-specific antigen after high-intensity focused ultrasonic ablation underwent MRI and endorectal biopsy. The MR images and biopsy results were correlated for six prostate sectors. Residual or recurrent prostate cancer after treatment was defined as local tumor progression if the biopsy results showed cancer foci. Two readers blinded to the clinical findings and biopsy results used a 5-point scale to independently assess DCE-MR images and T2-weighted and diffusion-weighted MR images. The results were compared by use of the McNemar test with Bonferroni correction, generalized estimating equations, and receiver operating characteristic analysis. RESULTS After high-intensity focused ultrasonic ablation, local tumor progression was pathologically detected in 54 (33%) of 162 sectors in 18 patients. The sensitivities of DCE-MRI and T2-weighted MRI with DWI were 80% and 63% for reader 1 (p = 0.004) and 87% and 70% for reader 2 (p = 0.004). The specificities of DCE-MRI and T2-weighted MRI with DWI were 68% and 78% for reader 1 (p = 0.002) and 63% and 74% for reader 2 (p < 0.001). The accuracy rates of DCE-MRI and T2-weighted MRI with DWI were 72% and 73% for reader 1 (p > 0.05) and 71% and 73% for reader 2 (p > 0.05). The areas under the receiver operating characteristic curve for DCE-MRI and T2-weighted MRI with DWI were 0.77 and 0.77 for reader 1 and 0.85 and 0.81 for reader 2. CONCLUSION For prediction of local tumor progression of prostate cancer after high-intensity focused ultrasonic ablation, DCE-MRI was more sensitive than T2-weighted MRI with DWI, but T2-weighted MRI with DWI was more specific than DCE-MRI.

Prospective evaluation of 3-T MRI performed before initial transrectal ultrasound-guided prostate biopsy in patients with high prostate-specific antigen and no previous biopsy.

OBJECTIVE The purpose of our study was to prospectively evaluate whether MRI before an initial transrectal ultrasound-guided biopsy contributed to detection of prostate cancer in patients with high prostate-specific antigen (PSA) level and no previous biopsy. SUBJECTS AND METHODS Men with an abnormal digital rectal examination or high PSA level were enrolled in this prospective randomized study. Participants were randomly allocated into two groups; the MRI group underwent 3-T MRI and then a transrectal ultrasound-guided biopsy with knowledge of the cancer location. The non-MRI group did not undergo MRI before transrectal ultrasound-guided biopsy. The cancer detection rate and positive core rate were obtained to compare the MRI and non-MRI groups. RESULTS The MRI and non-MRI groups contained 44 and 41 patients, respectively. There was no significant difference between the two groups with respect to age, PSA, and prostate volume. The MRI group (13/44, 29.5%) had a significantly higher cancer detection rate than the non-MRI group (4/41, 9.8%) (p = 0.03). The MRI group (52/527, 9.9%) had a significantly higher positive core rate than the non-MRI group (11/432, 2.5%) (p = 0.00). Regarding cancer detection rate and positive core rate, odds ratios were 3.9 (95% CI, 1.1-13.1) and 4.2 (95% CI, 2.2-8.1), respectively. CONCLUSION In patients with PSA level and no previous biopsy, 3-T MRI that is performed before transrectal ultrasound-guided biopsy may contribute to the detection of prostate cancer.

Lesion Localization in Patients With a Previous Negative Transrectal Ultrasound Biopsy and Persistently Elevated Prostate Specific Antigen Level Using Diffusion-Weighted Imaging at Three Tesla Before Rebiopsy

Objective:To assess the use of diffusion-weighted imaging (DWI) at 3 Tesla (T) for lesion localization in patients with a high risk of prostate cancer before a rebiopsy. Materials and Methods:A total of 43 patients (age range, 40–80 years; mean age, 62.6 years) who had previously undergone a transrectal ultrasound (TRUS)-guided biopsy that was negative and continued to have a persistent elevated prostate specific antigen level underwent DWI with b = 0 s/mm2 and b = 1000 s/mm2 before a rebiopsy. We located the area of the lowest apparent diffusion coefficient values and performed a target biopsy of that area, followed by a systematic biopsy under TRUS guidance. We evaluated the cancer detection rate, tumor location, and lesion visibility on T2-weighted imaging (T2WI) in patients with biopsy-proven cancers. Results:Prostate cancer was detected in 17 (39.5%) patients, and was more predominant in the transitional zone (76.4%, 13/17) than in the peripheral zone (23.6%, 4/17) (P < 0.05). Of the 17 cancers detected on DWI, 6 lesions were seen on T2WI. Conclusion:DWI in addition to T2WI at 3 T has the potential to provide important information on lesion localization in patients that had both previous negative TRUS biopsy and persistently elevated prostate specific antigen levels before a repeated biopsy.

Significance of 18F-fluorodeoxyglucose positron-emission tomography/computed tomography for the postoperative surveillance of advanced renal cell carcinoma

J O U R N A L C O M P I L A T I O N

GSTT1-null genotype is a protective factor against bladder cancer

OBJECTIVES To investigate the effects of homozygous deletions of GSTM1 and GSTT1 and smoking on bladder cancer, we conducted a case-control and ecological study. METHODS The case group consisted of 216 patients with bladder cancer and the control group of 449 healthy Koreans. Every subject was personally interviewed to obtain a detailed smoking history, and a multiplex polymerase chain reaction method was used to detect the presence or absence of the GSTM1 and GSTT1 genes. In the ecological study, age-standardized bladder cancer incidence and frequencies of GSTM1 and GSTT1-null types, estimated prevalence of cigarette smoking, and estimated per capita consumption of cigarettes per adult according to nationality and ethnicity were included. RESULTS In the Korean case-control data, smoking history and the GSTT1-null genotype were significantly associated with bladder cancer, and the GSTM1-null genotype was not. In the univariate and multivariate analyses with the ecological data of various countries and ethnic groups, cigarette smoking positively, but the frequency of the GSTT1-null type negatively, correlated with the age-standardized bladder cancer incidence. CONCLUSIONS These results suggest that the GSTT1-negative genotype might not be a risk factor but a protective factor of bladder cancer.

Role of multiparametric 3.0‐Tesla magnetic resonance imaging in patients with prostate cancer eligible for active surveillance

To evaluate predictors of more aggressive disease and the role of multiparametric 3.0‐T magnetic resonance imaging (MRI) in selecting patients with prostate cancer for active surveillance (AS).