Neoadjuvant Nivolumab Plus Gemcitabine/Cisplatin Chemotherapy in Muscle-Invasive Urothelial Carcinoma of the Bladder / Journal of the Korean Cancer Association, 대한암학회지

Purpose@#The activity and safety of neoadjuvant nivolumab plus gemcitabine/cisplatin (N+GC) were tested in patients with muscle-invasive bladder urothelial carcinoma (MIBC). @*Materials and Methods@#In a prospective phase II trial, patients with cT2-T4a N0 MIBC who were eligible for cisplatin and medically appropriate to undergo radical cystectomy (RC) were enrolled. Treatment with nivolumab 3 mg/kg on days 1 and 15 plus GC (cisplatin 70 mg/m2 on day 1, and gemcitabine 1,000 mg/m2 on days 1, 8, and 15) was repeated every 28 days up to 3 or 4 cycles, depending on the surgery schedules. The primary endpoint was pathologic complete response (pCR, ypT0). Secondary endpoints included pathologic downstaging (≤ ypT1), disease-free survival (DFS), and safety. @*Results@#Between September 2019 and October 2020, 51 patients were enrolled. Neoadjuvant N+GC was well tolerated. Among 49 patients who completed neoadjuvant N+GC, clinical complete response (cCR) was achieved in 59% of intent-to-treat (ITT) population. RC was performed in 34 (69%) patients. pCR was achieved in 24% (12/49) of ITT population and 35% (12/34) of RC patients. Median DFS was not reached. Over a median follow-up of 24 months, 12 patients experienced disease recurrence and were treated with palliative therapy or surgery. Although 12 patients declined surgery and were treated with concurrent chemoradiotherapy, DFS was longer in patients with cCR after neoadjuvant therapy than those without. Preoperative programmed death-ligand 1 (PD-L1) did not correlate with pCR or pathologic downstaging rates. @*Conclusion@#Neoadjuvant N+GC was feasible and provided meaningful pathologic responses in patients with MIBC, regardless of baseline PD-L1 expression (ONO-4538-X41; CRIS.nih.go.kr, KCT0003804).

Use of Imaging and Biopsy in Prostate Cancer Diagnosis:A Survey From the Asian Prostate Imaging Working Group

Objective@#To elucidate the use of radiological studies, including nuclear medicine, and biopsy for the diagnosis and staging of prostate cancer (PCA) in clinical practice and understand the current status of PCA in Asian countries via an international survey. @*Materials and Methods@#The Asian Prostate Imaging Working Group designed a survey questionnaire with four domains focused on prostate magnetic resonance imaging (MRI), other prostate imaging, prostate biopsy, and PCA backgrounds. The questionnaire was sent to 111 members of professional affiliations in Korea, Japan, Singapore, and Taiwan who were representatives of their working hospitals, and their responses were analyzed. @*Results@#This survey had a response rate of 97.3% (108/111). The rates of using 3T scanners, antispasmodic agents, laxative drugs, and prostate imaging-reporting and data system reporting for prostate MRI were 21.6%−78.9%, 22.2%−84.2%, 2.3%−26.3%, and 59.5%−100%, respectively. Respondents reported using the highest b-values of 800−2000 sec/mm2 and fields of view of 9−30 cm. The prostate MRI examinations per month ranged from 1 to 600, and they were most commonly indicated for biopsy-naïve patients suspected of PCA in Japan and Singapore and staging of proven PCA in Korea and Taiwan.The most commonly used radiotracers for prostate positron emission tomography are prostate-specific membrane antigen in Singapore and fluorodeoxyglucose in three other countries. The most common timing for prostate MRI was before biopsy (29.9%). Prostate-targeted biopsies were performed in 63.8% of hospitals, usually by MRI-ultrasound fusion approach. The most common presentation was localized PCA in all four countries, and it was usually treated with radical prostatectomy. @*Conclusion@#This survey showed the diverse technical details and the availability of imaging and biopsy in the evaluation of PCA. This suggests the need for an educational program for Asian radiologists to promote standardized evidence-based imaging approaches for the diagnosis and staging of PCA.

Paradigm Shift in Prostate Cancer Diagnosis: Pre-Biopsy Prostate Magnetic Resonance Imaging and Targeted Biopsy

With regard to the indolent clinical characteristics of prostate cancer (PCa), the more selective detection of clinically significant PCa (CSC) has been emphasized in its diagnosis and management. Magnetic resonance imaging (MRI) has advanced technically, and recent international cooperation has provided a standardized imaging and reporting system for prostate MRI. Accordingly, prostate MRI has recently been investigated and utilized as a triage tool before biopsy to guide tissue sampling to increase the detection rate of CSC beyond the staging tool for patients in whom PCa was already confirmed on conventional systematic biopsy. Radiologists must understand the current paradigm shift for better PCa diagnosis and management. This article reviewed the recent literature, demonstrating the diagnostic value of pre-biopsy prostate MRI with targeted biopsy and discussed unsolved issues regarding the paradigm shift in the diagnosis of PCa.

Risk Factors and Patterns of Locoregional Recurrence after Radical Nephrectomy for Locally Advanced Renal Cell Carcinoma / Journal of the Korean Cancer Association, 대한암학회지

Purpose@#We aimed to investigate the risk factors and patterns of locoregional recurrence (LRR) after radical nephrectomy (RN) in patients with locally advanced renal cell carcinoma (RCC). @*Materials and Methods@#We retrospectively analyzed 245 patients who underwent RN for non-metastatic pT3-4 RCC from January 2006 to January 2016. We analyzed the risk factors associated with poor locoregional control using Cox regression. Anatomical mapping was performed on reference computed tomography scans showing intact kidneys. @*Results@#The median follow-up duration was 56 months (range, 1 to 128 months). Tumor extension to renal vessels or the inferior vena cava (IVC) and Fuhrman’s nuclear grade IV were identified as independent risk factors of LRR. The 5-year actuarial LRR rates in groups with no risk factor, one risk factor, and two risk factors were 2.3%, 19.8%, and 30.8%, respectively (p < 0.001). The locations of LRR were distributed as follows: aortocaval area (n=2), paraaortic area (n=4), retrocaval area (n=5), and tumor bed (n=11). No LRR was observed above the celiac axis (CA) or under the inferior mesenteric artery (IMA). @*Conclusion@#Tumor extension to renal vessels or the IVC and Fuhrman’s nuclear grade IV were the independent risk factors associated with LRR after RN for pT3-4 RCC. The locations of LRR after RN for RCC were distributed in the tumor bed and regional lymphatic area from the bifurcation of the CA to that of the IMA.

Optimization of Multi-Atlas Segmentation with Joint Label Fusion Algorithm for Automatic Segmentation in Prostate MR Imaging

Purpose@#Joint label fusion (JLF) is a popular multi-atlas-based segmentation algorithm, which compensates for dependent errors that may exist between atlases.However, in order to get good segmentation results, it is very important to set the several free parameters of the algorithm to optimal values. In this study, we first investigate the feasibility of a JLF algorithm for prostate segmentation in MR images, and then suggest the optimal set of parameters for the automatic prostate segmentation by validating the results of each parameter combination. @*Materials and Methods@#We acquired T2-weighted prostate MR images from 20 normal heathy volunteers and did a series of cross validations for every set of parameters of JLF. In each case, the atlases were rigidly registered for the target image. Then, we calculated their voting weights for label fusion from each combination of JLF’s parameters (rpxy , rpz , rsxy , rsz , β). We evaluated the segmentation performances by five validation metrics of the Prostate MR Image Segmentation challenge. @*Results@#As the number of voxels participating in the voting weight calculation and the number of referenced atlases is increased, the overall segmentation performance is gradually improved. The JLF algorithm showed the best results for dice similarity coefficient, 0.8495 ± 0.0392; relative volume difference, 15.2353 ± 17.2350; absolute relative volume difference, 18.8710 ± 13.1546; 95% Hausdorff distance, 7.2366 ± 1.8502; and average boundary distance, 2.2107 ± 0.4972; in parameters of rpxy = 10, rpz = 1, rsxy = 3, rsz = 1, and β = 3. @*Conclusion@#The evaluated results showed the feasibility of the JLF algorithm for automatic segmentation of prostate MRI. This empirical analysis of segmentation results by label fusion allows for the appropriate setting of parameters.

Guidelines for Transrectal Ultrasonography-Guided Prostate Biopsy: Korean Society of Urogenital Radiology Consensus Statement for Patient Preparation, Standard Technique, and Biopsy-Related Pain Management

The Korean Society of Urogenital Radiology (KSUR) aimed to present a consensus statement for patient preparation, standard technique, and pain management in relation to transrectal ultrasound-guided prostate biopsy (TRUS-Bx) to reduce the variability in TRUS-Bx methodologies and suggest a nationwide guideline. The KSUR guideline development subcommittee constructed questionnaires assessing prebiopsy anticoagulation, the cleansing enema, antimicrobial prophylaxis, local anesthesia methods such as periprostatic neurovascular bundle block (PNB) or intrarectal lidocaine gel application (IRLA), opioid usage, and the number of biopsy cores and length and diameter of the biopsy needle. The survey was conducted using an Internet-based platform, and responses were solicited from the 90 members registered on the KSUR mailing list as of 2018. A comprehensive search of relevant literature from Medline database was conducted. The strength of each recommendation was graded on the basis of the level of evidence. Among the 90 registered members, 29 doctors (32.2%) responded to this online survey. Most KSUR members stopped anticoagulants (100%) and antiplatelets (76%) one week before the procedure. All respondents performed a cleansing enema before TRUS-Bx. Approximately 86% of respondents administered prophylactic antibiotics before TRUS-Bx. The most frequently used antibiotics were third-generation cephalosporins. PNB was the most widely used pain control method, followed by a combination of PNB plus IRLA. Opioids were rarely used (6.8%), and they were used only as an adjunctive pain management approach during TRUS-Bx. The KSUR members mainly chose the 12-core biopsy method (89.7%) and 18G 16-mm or 22-mm (96.5%) needles. The KSUR recommends the 12-core biopsy scheme with PNB with or without IRLA as the standard protocol for TRUS-Bx. Anticoagulants and antiplatelet agents should be discontinued at least 5 days prior to the procedure, and antibiotic prophylaxis is highly recommended to prevent infectious complications. Glycerin cleansing enemas and administration of opioid analogues before the procedure could be helpful in some situations. The choice of biopsy needle is dependent on the practitioners' situation and preferences.

Serial Comparison of Cancer Detection Rate Between Transrectal Ultrasound Sonography Guided Biopsy and Magnetic Resonance Imaging for Repeat Biopsy by a Propensity Score Matching Cohort: A Single Center Experience

PURPOSE: To compare biopsy performance of 2 approaches for multiparametric magnetic resonance imaging (MRI) guided biopsy and transrectal ultrasonography (TRUS)-guided biopsy with 2nd and 3rd repeat biopsy patients in prostate cancer detection. MATERIALS AND METHODS: This retrospective study reviewed 2,868 patients who was performed prostate biopsy between September 2013 to March 2017 at Samsung Medical Center, Seoul, Korea with TRUS-guided random biopsy and MRI fusion, MRI cognitive, and MRI-guided biopsy as 2nd and 3rd repeat biopsy and propensity matching was applied to reduce bias. Detection rate of each study was compared with 1:1 matching. RESULTS: Among 265 patients who performed TRUS 2nd biopsy, positivity rate for prostate cancer (PCa) was 18.49% (n=49/265) while 54.72% (n=145/265) for MRI-guided biopsy. In 3rd biopsy, positivity rate for PCa of TRUS biopsy was 17.74% (n=11/62) while 56.45% (n=35/62) for MRI guided biopsy. There was no significant difference in the detection rate for the patient with Gleason score 8 or more. CONCLUSIONS: MRI-guided biopsy was associated with a higher detection rate of prostate cancer with especially in patients with prior negative biopsy.

Prognostic Significance for Long-Term Outcomes Following Radical Prostatectomy in Men with Prostate Cancer: Evaluation with Prostate Imaging Reporting and Data System Version 2

OBJECTIVE: To retrospectively determine whether the use of the Prostate Imaging Reporting and Data System (PI-RADS) version 2 (v2) helps predict long-term outcomes for prostate cancer (PCa) patients following radical prostatectomy (RP). MATERIALS AND METHODS: A total of 166 patients with localized PCa evaluated with multiparametric magnetic resonance imaging (mpMRI) at 3T before RP were enrolled. Three groups were created based on PI-RADS v2 score used to predict clinical outcomes: group A, ≥ 3; group B, ≥ 4; group C, 5. We calculated biochemical recurrence-free survival (RFS) and progression-free survival (PFS). Cox proportion hazards models were used to identify variables predictive of biochemical recurrence and disease progression. RESULTS: During a median follow-up of 9.1 years, biochemical recurrence occurred in 67 patients (40.4%) and disease progression occurred in 55 patients (33.1%). In all groups, 10-year RFS and 10-year PFS were significantly lower for PI-RADS scores ≥ 3, ≥ 4 and 5 than for score < 3, < 4 and < 5 (p <0.05), respectively. In multivariate analysis, PI-RADS score ≥ 3 and score 5 were significant independent risk marker for biochemical recurrence (hazard ratio [HR] = 5.58, p = 0.018; HR = 1.75, p = 0.033) and disease progression (HR = 3.99, p = 0.047; HR = 2.31, p = 0.040). Moderate inter-observer agreement was seen for PI-RADS scoring. CONCLUSION: PI-RADS v2 may be used to predict long-term outcomes following RP in PCa.

Low-Tube-Voltage CT Urography Using Low-Concentration-Iodine Contrast Media and Iterative Reconstruction: A Multi-Institutional Randomized Controlled Trial for Comparison with Conventional CT Urography

OBJECTIVE: To compare the image quality of low-tube-voltage and low-iodine-concentration-contrast-medium (LVLC) computed tomography urography (CTU) with iterative reconstruction (IR) with that of conventional CTU. MATERIALS AND METHODS: This prospective, multi-institutional, randomized controlled trial was performed at 16 hospitals using CT scanners from various vendors. Patients were randomly assigned to the following groups: 1) the LVLC-CTU (80 kVp and 240 mgI/mL) with IR group and 2) the conventional CTU (120 kVp and 350 mgI/mL) with filtered-back projection group. The overall diagnostic acceptability, sharpness, and noise were assessed. Additionally, the mean attenuation, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and figure of merit (FOM) in the urinary tract were evaluated. RESULTS: The study included 299 patients (LVLC-CTU group: 150 patients; conventional CTU group: 149 patients). The LVLC-CTU group had a significantly lower effective radiation dose (5.73 ± 4.04 vs. 8.43 ± 4.38 mSv) compared to the conventional CTU group. LVLC-CTU showed at least standard diagnostic acceptability (score ≥ 3), but it was non-inferior when compared to conventional CTU. The mean attenuation value, mean SNR, CNR, and FOM in all pre-defined segments of the urinary tract were significantly higher in the LVLC-CTU group than in the conventional CTU group. CONCLUSION: The diagnostic acceptability and quantitative image quality of LVLC-CTU with IR are not inferior to those of conventional CTU. Additionally, LVLC-CTU with IR is beneficial because both radiation exposure and total iodine load are reduced.

Role of Magnetic Resonance Imaging Using Prostate Imaging-Reporting and Data System Version 2 to Predict Clinically Significant Cancer After Radical Prostatectomy in Very Low-Risk or Low-Risk Prostate Cancer

PURPOSE: To determine the negative predictive value (NPV) of multiparametric magnetic resonance imaging (mp-MRI) for clinically significant cancer (CSC) based on the Prostate Imaging-Reporting and Data System (PI-RADS) version 2 in very low-risk or low-risk prostate cancer patients. MATERIALS AND METHODS: We retrospectively analyzed 380 patients with low risk of prostate cancer who underwent mp-MRI before radical prostatectomy (RP) from 2011 to 2013. Of the 380 patients, 142 patients were in the very low risk group. CSC at RP was defined as follows: any T3−4, G3+4 with tumor volume>15%, G4+3 or higher. In the very low risk and low risk groups, we analyzed the rate of CSC according to PI-RADS score and calculated the NPV of mp-MRI for detection of CSC. RESULTS: In the low risk group, 20.8% (n=79) of patients had PI-RADS version 2 score 1–2 and 17.4% (n=66) of patients had PI-RADS version 2 score 3. In the very low risk group, 26.8% (n=38) of patients had PI-RADS version 2 score 1–2 and 17.6% (n=25) of patients had PI-RADS version 2 score 3 in the very low risk group. Rates of CSC were 33.7% (n=128) and 16.9% (n=24) in the low risk and very low risk groups, respectively. The NPV of MRI was 93.7% in the very low risk group and 78.6% in the low risk group. CONCLUSIONS: The NPV of PI-RADS for CSC is high in the very low risk group, but not in the low risk group. Further multicenter studies are needed to investigate the utility of PI-RADS version 2 for NPV.

Comparison of Biopsy Results and Surgical Outcomes of Magnetic Resonance Imaging-Guided and Transrectal Ultrasonography-Guided Repeat Biopsy

PURPOSE: We compared biopsy results and surgical outcomes of magnetic resonance imaging (MRI)-guided biopsy with transrectal ultrasonography (TRUS)-guided biopsy to demonstrate efficacy of MRI-guided biopsy on previous biopsy negative patients. MATERIALS AND METHODS: We retrospectively reviewed data of 120 patients who were categorized into MRI-guided biopsy groups (n=20) and TRUS-guided biopsy groups (n=100). All patients were diagnosed with prostate cancer (PCa) and had undergone radical prostatectomy (RP) after MRI-guided or TRUS-guided repeat biopsy between January 2010 and March 2016. Detection rate of significant cancer and Gleason score upgrading and downgrading were examined, in addition to biopsy results and subsequent RP outcomes. RESULTS: Median values for prostate-specific antigen level of the TRUS-guided biopsy group and the MRI-guided biopsy group were 6.67 and 5.86 ng/mL (p=0.303), respectively. Median prostate volume of each group (34.1 mL vs. 23.5 mL, p=0.007), number of positive cores (2.0 vs. 3.0, p=0.001) and maximum cancer/core rate (30.0% vs. 60.0%, p<0.001) were statistically different. Positive core rates of each group were 21.9% and 87.1%, respectively. Pathologic T stage was the only variable that showed difference in surgical outcomes (p=0.002). Most of PCa was confirmed as clinically significant PCa after RP in MRI-guided biopsy group (95%). CONCLUSIONS: MRI-guided biopsy showed higher positive core rate and detection rate of clinically significant PCa than TRUS-guided biopsy in repeat biopsy setting. Prospective multicenter large-scale study and accumulation of data is expected to further define superiority of the MRI-guided biopsy.

CT-Guided Radiofrequency Ablation of T1a Renal Cell Carcinoma in Korea: Mid-Term Outcomes

OBJECTIVE: To evaluate the mid-term outcomes of percutaneous radiofrequency ablation (RFA) treatment in patients with small (< 4 cm) renal cell carcinoma (RCC) in Korea. MATERIALS AND METHODS: Between 2010 and 2015, 51 patients (40 men and 11 women; median age, 57 years) with biopsyproven 51 RCC were treated using CT-guided RFA. All patients were clinically staged T1aN0M0 prior to RFA. The median tumor size and follow-up period were 2.1 cm (range, 1.0-3.9 cm) and 26 months (4-60 months), respectively. Local tumor progression, distant metastasis, primary and secondary effectiveness rates, and major complication rates were recorded. Estimated glomerular filtration rates (GFRs) between pre-RFA and last follow-up were compared using paired t tests. The 2-year recurrence-free survival rate was calculated using Kaplan-Meier survival analysis. RESULTS: Of the 51 patients, 2 (3.9%) experienced local tumor progression, and 1 (2.0%) had lymph node metastasis after the first RFA session. Primary and secondary effectiveness rates were 96.1% (49/51) and 100% (1/1), respectively. Only 1 patient experienced a major complication (uretero-pelvic stricture) after the second RFA session for treating a local tumor progression, and the major complication rate was 1.9% (1/52). The median pre-RFA and last follow-up GFRs were 87.1 mL/ min/1.73 m2 (14.2-142.7 mL/min/1.73 m2) and 72.0 mL/min/1.73 m2 (7.2-112.6 mL/min/1.73 m2), respectively (p < 0.0001). The 2-year recurrence-free survival rate was 96.0%. CONCLUSION: CT-guided RFA is a safe and effective treatment in Korean patients with T1a RCC because of excellent mid-term outcomes.

Long-term outcomes of magnetic resonance imaging-invisible endometrial cancer / 부인종양

OBJECTIVE: Magnetic resonance imaging (MRI) is useful for staging endometrial cancer. The treatment and prognosis of MRI-invisible endometrial cancer remain unclear. The purpose of this study was to retrospectively evaluate the long-term outcomes of patients with MRI-invisible endometrial cancer. METHODS: Between February 1995 and December 2011, we reviewed the medical records of 433 patients with endometrial cancer, which was staged IA on MRI. Of these patients, 89 had MRI-invisible cancer and 344 had MRI-visible cancer. Both cancers were treated with simple hysterectomy with or without lymph node dissection according to the surgeon's decision. Both cancers were compared regarding pathologic findings, recurrence rates, and survival rates. RESULTS: The median sizes of MRI-invisible and MRI-visible cancers were 4 mm (0 to 40 mm) and 20 mm (0 to 89 mm), respectively (p<0.001). Myometrial invasion of these groups were detected in 20.2% (18/89) and 56.7% (195/344), respectively (p<0.001). Lymphadenectomy and follow-up imaging revealed no lymph node metastasis in patients with MRI-invisible cancers, while those revealed in 4.7% (16/344) of patients with MRI-visible cancers (p=0.052). The recurrence rates of MRI-invisible and MRI-visible cancers were 1.1% (1/89) and 7.8% (27/344), respectively (p=0.026). The recurrence-free survival rates of these groups were 98.9% (88/89) and 91.6% (315/344), respectively (p=0.022). CONCLUSION: MRI-invisible endometrial cancer can be treated with less invasive surgery because of its lower tumor burden and better prognosis. This cancer may not require lymphadenectomy because of no metastasis or recurrence in lymph nodes.

Long-term outcomes of magnetic resonance imaging-invisible endometrial cancer / 부인종양

OBJECTIVE: Magnetic resonance imaging (MRI) is useful for staging endometrial cancer. The treatment and prognosis of MRI-invisible endometrial cancer remain unclear. The purpose of this study was to retrospectively evaluate the long-term outcomes of patients with MRI-invisible endometrial cancer. METHODS: Between February 1995 and December 2011, we reviewed the medical records of 433 patients with endometrial cancer, which was staged IA on MRI. Of these patients, 89 had MRI-invisible cancer and 344 had MRI-visible cancer. Both cancers were treated with simple hysterectomy with or without lymph node dissection according to the surgeon's decision. Both cancers were compared regarding pathologic findings, recurrence rates, and survival rates. RESULTS: The median sizes of MRI-invisible and MRI-visible cancers were 4 mm (0 to 40 mm) and 20 mm (0 to 89 mm), respectively (p<0.001). Myometrial invasion of these groups were detected in 20.2% (18/89) and 56.7% (195/344), respectively (p<0.001). Lymphadenectomy and follow-up imaging revealed no lymph node metastasis in patients with MRI-invisible cancers, while those revealed in 4.7% (16/344) of patients with MRI-visible cancers (p=0.052). The recurrence rates of MRI-invisible and MRI-visible cancers were 1.1% (1/89) and 7.8% (27/344), respectively (p=0.026). The recurrence-free survival rates of these groups were 98.9% (88/89) and 91.6% (315/344), respectively (p=0.022). CONCLUSION: MRI-invisible endometrial cancer can be treated with less invasive surgery because of its lower tumor burden and better prognosis. This cancer may not require lymphadenectomy because of no metastasis or recurrence in lymph nodes.

Magnetic Resonance Imaging-Guided Prostate Biopsy: Present and Future

Systemic transrectal ultrasound-guided biopsy (TRUSBx) is the standard procedure for diagnosing prostate cancer (PCa), but reveals a limited accuracy for the detection of cancer. Currently, multiparametric MR imaging (mp-MRI) is increasingly regarded as a promising method to detect PCa with an excellent positive predictive value. The use of mp-MRI during a MRI-guided biopsy (MRGB) procedure improves the quality of a targeted biopsy. The aim of this article is to provide an overview about the MRGB technique for PCa detection, to review the accuracy and clinical indications of MRGB and discuss its current issues and further directions. A MRGB seems accurate and efficient for the detection of clinically significant PCa in men with previous negative TRUSBx. Moreover, it may decrease the detection of clinically insignificant cancers with fewer biopsy cores.

Contrast-Induced Nephropathy in Patients Undergoing Intravenous Contrast-Enhanced Computed Tomography in Korea: A Multi-Institutional Study in 101487 Patients

OBJECTIVE: To evaluate the prevalence of known risk factors for contrast-induced nephropathy (CIN) and their association with the actual occurrence of CIN in patients undergoing intravenous contrast-enhanced computed tomography (CECT) in Korea. MATERIALS AND METHODS: Patients who underwent CECT in 2008 were identified in the electronic medical records of 16 tertiary hospitals of Korea. Data on demographics, comorbidities, prescriptions and laboratory test results of patients were collected following a standard data extraction protocol. The baseline renal function was assessed using the estimated glomerular filtration rate (eGFR). We identified the prevalence of risk factors along the eGFR strata and evaluated their influence on the incidence of CIN, defined as a 0.5 mg/dL or 25% increase in serum creatinine after CECT. RESULTS: Of 432425 CECT examinations in 272136 patients, 140838 examinations in 101487 patients met the eligibility criteria for analysis. The mean age of the participants was 57.9 +/- 15.5 years; 25.1% of the patients were older than 70 years. The prevalence of diabetes mellitus was 11.9%, of hypertension 13.7%, of gout 0.55% and of heart failure was 1.7%. Preventive measures were used in 40238 CECT examinations (28.6%). The prevalence of risk factors and use of preventive measures increased as the renal function became worse. A CIN was occurred after 3103 (2.2%) CECT examinations, revealing a significant association with decreased eGFR, diabetes mellitus, and congestive heart failure after adjustment. CONCLUSION: Risk factors for CIN are prevalent among the patients undergoing CECT. Preventive measures were seemingly underutilized and a system is needed to improve preventive care.

Dynamic Contrast-Enhanced MR Imaging in Detecting Local Tumor Progression after HIFU Ablation of Localized Prostate Cancer

PURPOSE: To retrospectively evaluate the diagnostic performance of dynamic contrast-enhanced MR imaging (DCE-MRI) in detecting recurrent prostate cancer after HIFU of clinically localized cancer, as compared with T2-weighted imaging (T2WI). MATERIALS AND METHODS: Twenty-six patients with increased prostate-specific antigen levels after HIFU were included in this study. All MR examinations were performed using T2WI and DCE-MRI, followed by transrectal ultrasound-guided biopsy. MRI and biopsy results were correlated in six prostate sectors. Residual or recurrent cancer after HIFU was defined as local tumor progression if biopsy results showed any cancer foci. Two independent readers interpreted the MR images. RESULTS: Of 156 prostate sectors, 51 (33%) were positive for cancer in 17 patients. For detecting local tumor progression, the sensitivity of DCE-MRI and T2WI was 80% and 57% for reader 1 (P 0.05). Interobserver agreement of DCE-MRI and T2WI was moderate and fair, respectively. CONCLUSION: For detecting local tumor progression of prostate cancer after HIFU, DCE-MRI was more sensitive than T2WI, with less interobserver variability.

Diffusion-Weighted Magnetic Resonance Imaging for the Evaluation of Prostate Cancer: Optimal B Value at 3T

OBJECTIVE: To retrospectively determine the optimal b value of diffusion-weighted imaging (DWI) for predicting the presence of localized prostate cancer, and to evaluate the utility of DWI under different b values in differentiating between cancers and benign prostatic tissues. MATERIALS AND METHODS: Eighty patients with suspected prostate cancer underwent MRI including DWI at 3T, followed by radical prostatectomy. DWI was examined under different b values. Apparent diffusion coefficient (ADC) maps were generated by using b = 0, and other b values of 300, 700, 1000 or 2000 s/mm2. For predicting the presence of cancers, four different ADC maps were analyzed independently by two blinded readers. ADCs were measured in benign and malignant tissues. RESULTS: For predicting the presence of 110 prostate cancers, the sensitivity and area under the curve (AUC) for an experienced reader was significantly greater at b = 1000 (85% and 0.91) than b = 300, 700 or 2000 s/mm2 (p < 0.01). For a less-experienced reader, the AUC was significantly greater at b = 700, 1000 or 2000 than b = 300 s/mm2 (p < 0.01). Mean ADCs of the cancers in sequence from b = 300 to 2000 s/mm2 were 1.33, 1.03, 0.88 and 0.68 x 10(-3) mm2/s, which were significantly lower than those of benign tissues (p < 0.001). CONCLUSION: The optimal b value for 3T DWI for predicting the presence of prostate cancer may be 1000 s/mm2.

Post-transplant Lymphoproliferative Disorder Arising from Renal Allograft Parenchyma: A Case Report

Post-transplant lymphoproliferative disorder (PTLD) is a rare but serious complication that occurs in patients undergoing kidney transplantation. PTLD usually manifests as a renal hilar mass comprised of histologically B-lymphocytes. We report our experience of managing a patient with PTLD arising from renal parenchyma. Ultrasonographic and MR imaging features of this unusual PTLD suggested differentiated renal cell carcinoma arising from the renal allograft.

The Role of Endorectal Magnetic Resonance Imaging in Predicting Extraprostatic Extension and Seminal Vesicle Invasion in Clinically Localized Prostate Cancer

PURPOSE: We aimed to assess the clinical value of endorectal magnetic resonance imaging (MRI) in predicting extraprostatic extension and seminal vesicle invasion in patients with clinically localized prostate cancer. MATERIALS AND METHODS: A total of 54 patients who underwent radical prostatectomy for clinically localized prostate cancer were retrospectively analyzed. The findings of endorectal MRI, performed at least 3 weeks after biopsy, were compared with the pathological results of radical prostatectomy specimens. The sensitivity, specificity, and accuracy of the detection of extraprostatic extension and seminal vesicle invasion were calculated. RESULTS: The sensitivity, specificity, and accuracy of the endorectal MRI findings were 50.0%, 82.6%, and 77.8% for the detection of extraprostatic extension, respectively, and 75.0%, 92.0%, and 90.7% for the detection of seminal vesicle invasion, respectively. The sensitivity of endorectal MRI in the detection of extraprostatic extension improved as the Gleason score increased. CONCLUSIONS: Endorectal MRI findings demonstrated modest sensitivity for predicting extraprostatic extension, whereas specificity was relatively high. In addition, endorectal MRI showed better sensitivity for detecting high-grade tumors.