Computer-aided diagnosis with a convolutional neural network algorithm for automated detection of urinary tract stones on plain X-ray.

BACKGROUND: Recent increased use of medical images induces further burden of their interpretation for physicians. A plain X-ray is a low-cost examination that has low-dose radiation exposure and high availability, although diagnosing urolithiasis using this method is not always easy. Since the advent of a convolutional neural network via deep learning in the 2000s, computer-aided diagnosis (CAD) has had a great impact on automatic image analysis in the urological field. The objective of our study was to develop a CAD system with deep learning architecture to detect urinary tract stones on a plain X-ray and to evaluate the model's accuracy. METHODS: We collected plain X-ray images of 1017 patients with a radio-opaque upper urinary tract stone. X-ray images (n = 827 and 190) were used as the training and test data, respectively. We used a 17-layer Residual Network as a convolutional neural network architecture for patch-wise training. The training data were repeatedly used until the best model accuracy was achieved within 300 runs. The F score, which is a harmonic mean of the sensitivity and positive predictive value (PPV) and represents the balance of the accuracy, was measured to evaluate the model's accuracy. RESULTS: Using deep learning, we developed a CAD model that needed 110 ms to provide an answer for each X-ray image. The best F score was 0.752, and the sensitivity and PPV were 0.872 and 0.662, respectively. When limited to a proximal ureter stone, the sensitivity and PPV were 0.925 and 0.876, respectively, and they were the lowest at mid-ureter. CONCLUSION: CAD of a plain X-ray may be a promising method to detect radio-opaque urinary tract stones with satisfactory sensitivity although the PPV could still be improved. The CAD model detects urinary tract stones quickly and automatically and has the potential to become a helpful screening modality especially for primary care physicians for diagnosing urolithiasis. Further study using a higher volume of data would improve the diagnostic performance of CAD models to detect urinary tract stones on a plain X-ray.

Trends and safety of robot-assisted partial nephrectomy during the initial 2-year period after government approval in Japan: A nationwide database study from 2016 to 2018.

OBJECTIVES: To evaluate the trends and safety of robot-assisted partial nephrectomy during the initial 2-year period after government approval for this type of procedure in April 2016. METHODS: This nationwide retrospective study included 3722 received robot-assisted partial nephrectomy cases carried out from April 2016 to March 2018 in 124 participating institutions. The institutions were divided into lower- and higher-volume institutions according to the median of 19 robot-assisted partial nephrectomy cases during the study period. Surgical outcomes between 616 cases from lower-volume institutions and 3106 cases from higher-volume institutions were compared using propensity score matching. RESULTS: During the study period, both the number of robot-assisted partial nephrectomy surgeries and the number of institutions in which the surgery was carried out steadily increased. Overall, the median anesthesia time was 217 min, the median postoperative length of stay was 9 days, and the proportion of blood transfusions, complications and readmissions were 0.8%, 5.1% and 1.0%, respectively. There were no significant differences in anesthesia time, incidence of blood transfusions, and complication rates between the lower-volume and higher-volume institutions. However, a slightly, but significantly, longer postoperative length of stay and a lower incidence of readmission were observed in lower-volume institutions both before and after propensity score matching. CONCLUSIONS: Robot-assisted partial nephrectomy has become widespread during the initial 2-year period after government approval with an acceptable safety profile, regardless of the institutional caseloads. This technique has become a standard of care for stage 1 renal cancer patients in Japan.

Renal epithelioid angiomyolipoma: Incidence in a Japanese cohort and diagnostic utility of diffusion-weighted magnetic resonance imaging.

OBJECTIVES: To show the epidemiological characteristics of epithelioid angiomyolipoma in a Japanese population, and to establish the preoperative diagnosis method of epithelioid angiomyolipoma. METHODS: Among the 855 tumors of patients who underwent partial/radical nephrectomy or renal biopsy for presumed renal cell carcinoma between 2007 and 2018, 39 renal tumors were diagnosed as nonclassical angiomyolipoma, including epithelioid angiomyolipoma and fat-poor angiomyolipoma. We retrospectively evaluated the incidence of epithelioid angiomyolipoma. Furthermore, we analyzed computed tomography and magnetic resonance imaging results, including diffusion-weighted magnetic resonance imaging findings of epithelioid angiomyolipoma and fat-poor angiomyolipoma. RESULTS: The incidence of epithelioid angiomyolipoma (n = 7) was 17.9% of surgically resected non-classical angiomyolipoma. The radiological appearance of epithelioid angiomyolipoma was hyperattenuating on unenhanced computed tomography images with iso or low intensity on T2-weighted magnetic resonance imaging. The mean apparent diffusion coefficient value of the solid component in epithelioid angiomyolipoma was significantly lower than that in fat-poor angiomyolipoma (median 0.79 × 10-3 vs 1.07 × 10-3 mm2 /s, P = 0.0019). CONCLUSIONS: The proportion of epithelioid angiomyolipoma in our Japanese cohort was equivalent to that of the reported series in the USA. The apparent diffusion coefficient value is potentially useful to differentiate between epithelioid angiomyolipoma and fat-poor angiomyolipoma. Further research is required to establish the imaging diagnostic criteria for epithelioid angiomyolipoma.

Value of extra-target prostate biopsy for the detection of magnetic resonance imaging-missed adverse pathology according to the Prostate Imaging Reporting and Data System scores: Spatial analysis using magnetic resonance-ultrasound fusion images.

OBJECTIVES: To clarify who benefits from extra-target sampling of systematic prostate biopsy to detect magnetic resonance imaging-missed significant cancer and upgrading, when concurrently carried out with magnetic resonance imaging-ultrasound fusion targeted biopsy. METHODS: Targeted biopsy and systematic biopsy were carried out in 301 men with Prostate Imaging Reporting and Data System scores ≥3. All score ≥3 regions were designated as targets. According to patients' highest Prostate Imaging Reporting and Data System scores, spatial relations between targets and biopsy-proven cancer were investigated to identify magnetic resonance imaging-missed pathology. RESULTS: Overall, targeted biopsy and systematic biopsy detected significant cancer in 56.5% and 46.5%, respectively (P < 0.001). Significant cancer was detected only by systematic biopsy in 7.0%, and only outside targets in 5.0%. Upgrading by systematic biopsy was observed in 16.3%, and occurred outside targets in 11.0%. On multivariate analysis, the highest Prostate Imaging Reporting and Data System 4 was predictive for significant cancer only outside targets (odds ratio 5.81, P = 0.002) and for upgrading derived from outside targets (odds ratio 2.64, P = 0.012). According to the scores of 3, 4 and 5, significant cancer was identified only outside targets in 1.0%, 11.2% and 2.9%, respectively (P = 0.003 for Prostate Imaging Reporting and Data System 3 vs 4; P = 0.019 for Prostate Imaging Reporting and Data System 4 vs 5), and upgrading occurred in 6.1%, 18.4% and 8.6%, respectively (P = 0.009 and 0.040). CONCLUSIONS: Men with the highest Prostate Imaging Reporting and Data System score 4 receive the largest benefit from extra-target biopsy for magnetic resonance imaging-missed significant cancer detection and upgrading. In men with a score of 3, less adverse pathology is missed without extra-target biopsy. These findings suggest prostate biopsy strategy could be tailored according to Prostate Imaging Reporting and Data System scores.

Postoperative renal impairment and longitudinal change in renal function after adrenalectomy in patients with Cushing's syndrome.

OBJECTIVES: To evaluate the renal function after adrenalectomy in patients with Cushing's syndrome in comparison with that in patients with primary aldosteronism. METHODS: This retrospective study included 35 patients with Cushing's syndrome and 51 patients with primary aldosteronism who underwent unilateral adrenalectomy and were followed up for >6 months. The renal function was analyzed before and after adrenalectomy using the estimated glomerular filtration rate. Postoperative renal impairment was defined as a >25% reduction in the estimated glomerular filtration rate from baseline at 1 month after adrenalectomy. Multivariate logistic regression analyses were carried out to examine whether the differences between Cushing's syndrome and primary aldosteronism increased the risk of postoperative renal impairment. Longitudinal changes were calculated starting 1 month after adrenalectomy using the linear mixed model. RESULTS: The mean estimated glomerular filtration rate in both groups significantly decreased at 1 month after adrenalectomy from baseline. Postoperative renal impairment was observed in four (11%) and 12 (24%) patients in the Cushing's syndrome and primary aldosteronism groups, respectively. Multivariate analysis showed that preoperative systolic blood pressure was independently associated with postoperative renal impairment, but not with the type of the disease. There was no significant increase or decrease in postoperative estimated glomerular filtration rate observed after the initial decrease after adrenalectomy in either group. CONCLUSIONS: Patients with Cushing's syndrome show the same persistent renal impairment after adrenalectomy as that reported in patients with primary aldosteronism. Attention should be given to possible masked renal damage in clinical practice for the management of Cushing's syndrome.

Feasibility and outcomes of selective tetramodal bladder-preservation therapy in elderly patients with muscle-invasive bladder cancer.

OBJECTIVE: To assess the feasibility and functional/oncological outcomes of selective tetramodal bladder-preservation therapy in elderly patients with muscle-invasive bladder cancer. METHODS: This study analyzed 154 patients with non-metastatic muscle-invasive bladder cancer who were enrolled into the protocol. After maximal transurethral resection and induction chemoradiotherapy, patients with clinical complete response were offered consolidative partial cystectomy to achieve bladder preservation; otherwise, radical cystectomy was recommended. Postoperative complications, preserved bladder function, and oncological outcomes were compared between elderly (aged ≥75 years) and younger patients (aged <75 years). Frailty and sarcopenia were further assessed as potential factors that could affect the feasibility and outcomes of the protocol. RESULTS: A total of 44 patients (29%) were elderly, and 31 (20%) were frail (modified frailty index 2-3). Sarcopenia was observed in 68 (54%) of 126 eligible patients. Clinical complete response to induction chemoradiotherapy was achieved in 125 (81%) patients, and the bladder-preservation protocol was completed in 107 (69%) patients with consolidative partial cystectomy. Over a median follow-up period of 48 months, 5-year cancer-specific and muscle-invasive bladder cancer recurrence-free survival rates after protocol completion were 98% and 95%, respectively. There were no significant differences in complication rates related to partial cystectomy, preserved bladder function, and oncological outcomes between the elderly and younger groups. Neither frailty nor sarcopenia negatively affected these outcomes. CONCLUSIONS: Tetramodal bladder-sparing therapy incorporating consolidative partial cystectomy is feasible and yielded favorable functional/oncological outcomes in patients with muscle-invasive bladder cancer, regardless of advanced age, frailty or sarcopenia. This protocol could be a viable treatment option for such high-risk patient populations.

Selective tetramodal bladder-preservation therapy, incorporating induction chemoradiotherapy and consolidative partial cystectomy with pelvic lymph node dissection for muscle-invasive bladder cancer: oncological and functional outcomes of 107 patients.

OBJECTIVES: To evaluate the oncological and functional outcomes associated with selective tetramodal bladder-sparing therapy, comprising maximal transurethral resection of bladder tumour (TURBT), induction chemoradiotherapy (CRT), and consolidative partial cystectomy (PC) with pelvic lymph node dissection (PLND). MATERIALS AND METHODS: In the present study, 154 patients with non-metastatic muscle-invasive bladder cancer (MIBC), prospectively enrolled in the tetramodal bladder-preservation protocol, were analysed. After TURBT and induction CRT, patients showing complete remission were offered consolidative PC with PLND for the achievement of bladder preservation. Pathological response to induction CRT was evaluated using PC specimens. Oncological and functional outcomes after bladder preservation were evaluated using the following endpoints: MIBC-recurrence-free survival (RFS); cancer-specific survival (CSS); overall survival (OS), and cross-sectional assessments of preserved bladder function and quality of life (QoL) including uroflowmetry, bladder diary, International Prostate Symptom Score, Overactive Bladder Symptom Score and the 36-item Short-Form Health Survey (SF-36) score. RESULTS: The median follow-up period was 48 months. Complete MIBC remission was achieved in 121 patients (79%) after CRT, and 107 patients (69%) completed the tetramodal bladder-preservation protocol comprising consolidative PC with PLND. Pathological examination in these 107 patients revealed residual invasive cancer (≥pT1) that was surgically removed in 11 patients (10%) and lymph node metastases in two patients (2%). The 5-year MIBC-RFS, CSS and OS rates in the 107 patients who completed the protocol were 97%, 93% and 91%, respectively. As for preserved bladder function, the median maximum voided volume, post-void residual urine volume, and nighttime frequency were 350 mL, 25 mL, and two voids, respectively. In the SF-36, patients had favourable scores, equivalent to the age-matched references in all the QoL scales. CONCLUSION: Selective tetramodal bladder-preservation therapy, incorporating consolidative PC with PLND, yielded favourable oncological and functional outcomes in patients with MIBC. Consolidative PC may have contributed to the low rate of MIBC recurrence in patients treated according to this protocol.

Usefulness of the inchworm sign on DWI for predicting pT1 bladder cancer progression.

OBJECTIVE: To evaluate the significance of the presence or absence of an "inchworm sign" on DWI for the recurrence and progression of T1 bladder cancer. MATERIALS AND METHODS: We retrospectively analyzed 91 patients with pT1 urothelial carcinoma who underwent DWI prior to transurethral resection between 2007 and 2016. DWI of the dominant tumors was scrutinized for inchworm signs at b = 1000 s/mm2. The association of the presence of the inchworm sign with progression and recurrence was analyzed; progression was defined as recurrence to stage T2 or higher and/or N+, and/or M1. RESULTS: An inchworm sign was seen in 65 cases (71%), while it was absent in 26 cases. Among the 65, 25 (38%) had confirmed tumor recurrence, while in the remaining 26, 14 (54%) had confirmed recurrence (median time post TURB = 7.9 and 10.1 months for each). At the time of recurrence, the tumor had progressed in one (2%) inchworm-sign-positive and seven (27%) inchworm-sign-negative cases. The progression rate of inchworm-sign-negative cases was significantly higher than that of inchworm-sign-positive cases (hazard ratio = 17.2, p = 0.0017), whereas there was no significant difference in the recurrence rate between two groups. The absence of an inchworm sign and histological grade 3 were independent risk factors for progression (p < 0.001 and 0.010, respectively). CONCLUSIONS: The absence of an inchworm sign on DWI was a significant prognostic factor for progression of T1 bladder cancer. Morphological evaluation of DWI signals may therefore be a useful adjunct to preoperative assessment of biological aggressiveness. KEY POINTS: • An inchworm sign is a simple diagnostic criterion that characterizes only the shape of the tumor signal on DWI, and potentially serves as an imaging biomarker to predict clinical aggressiveness. • The absence of an inchworm sign on DWI is a significant indicator of progression of T1 bladder cancer.

Predictive ability of renal cortex enhancement in dynamic computed tomography for residual renal function after nephroureterectomy: Comparison with 99m Tc-diethylenetriaminopentacetic acid renography and validation study.

OBJECTIVE: To estimate postoperative residual renal function after radical nephroureterectomy for upper tract urothelial carcinoma using the preoperative dynamic computed tomography renal cortex enhancement ratio in comparison with the split kidney glomerular filtration rate measured by 99m Tc-diethylenetriaminopentacetic acid renography. METHODS: A total of 47 patients who received radical nephroureterectomy and underwent both preoperative dynamic computed tomography and renography were the model-development cohort; and 109 patients who underwent dynamic computed tomography alone were the validation cohort. Postoperative renal function of the unremoved kidney was estimated using the following formulas: preoperative estimated glomerular filtration rate × the percentage of total renal cortex radiodensity for the intact kidney in Hounsfield units obtained from corticomedullary phase images in the computed tomography-based model, or the percentage of the total glomerular filtration rate measured by renography in the nuclear model. The correlation between observed and estimated postoperative renal function was determined. The computed tomography-based prediction model derived from linear regression analysis was validated externally. RESULTS: The correlation of computed tomography-based split renal function with the observed postoperative estimated glomerular filtration rate (r = 0.80) was equivalent to that of nuclear split renal function (r = 0.78). In the validation cohort, the computed tomography-based prediction model showed an equivalently strong correlation (r = 0.78). CONCLUSIONS: The present study showed that the percentage of total renal cortex radiodensity for the intact kidney is a useful tool for predicting unremoved kidney function in upper tract urothelial carcinoma patients, thereby allowing appropriate patient selection for perioperative cisplatin-based combination chemotherapy.

Acute kidney injury and intermediate-term renal function after clampless partial nephrectomy.

OBJECTIVES: To evaluate the incidence and predictors of acute kidney injury after clampless partial nephrectomy, and its impact on intermediate-term renal function. METHODS: The incidence and severity of acute kidney injury were assessed for 262 patients undergoing clampless partial nephrectomy between 2010 and 2015. The association between perioperative covariates and acute kidney injury was evaluated using multivariate logistic regression analysis. An annual change in estimated glomerular filtration rate from 1 year after surgery was calculated according to the presence or absence of acute kidney injury. An impact of acute kidney injury on postoperative renal impairment, defined as a ≥25% estimated glomerular filtration rate decrease, was evaluated. RESULTS: Overall, 21 (8.0%) patients experienced grade 1 acute kidney injury after clampless partial nephrectomy, and grade ≥2 acute kidney injury was not observed. High tumor complexity was the only independent predictor of acute kidney injury. Estimated glomerular filtration rate in patients with acute kidney injury improved within 1 year, and annual estimated glomerular filtration rate changes were similar among patients with or without acute kidney injury. Ultimately, 13 (5.0%) patients showed postoperative renal impairment during the median follow-up period of 37 months. Advanced age and diabetes mellitus were independent risk factors for renal impairment, but acute kidney injury was not. CONCLUSIONS: The incidence and severity of acute kidney injury after clampless partial nephrectomy are low. Low-grade acute kidney injury after clampless partial nephrectomy does not seem to affect intermediate-term renal function.

Incidence and predictive factors of hypoglycemia after pheochromocytoma resection.

OBJECTIVES: To determine the incidence and preoperative risk factors of post-excisional hypoglycemia in patients undergoing pheochromocytoma resection. METHODS: Patients who underwent surgical resection of pheochromocytoma at a single institution were retrospectively enrolled in the present study. The primary end-point was the development of post-excisional hypoglycemia; that is, a serum glucose level <70 mg/dL. The serum levels of immunoreactive insulin and glucose levels during the preoperative oral glucose-tolerance test and surgery were analyzed to elucidate the mechanism of hypoglycemia. RESULTS: A total of 49 patients underwent surgical resection of pheochromocytoma, of which 21 patients (43%) developed post-excisional hypoglycemia. The incidence of hypoglycemia was not statistically different between patients with adrenal tumors and those with extra-adrenal tumors (18/41 [44%] vs 3/8 [38%], respectively, P = 0.73). There was no difference in the immunoreactive insulin/glucose ratio during the preoperative oral glucose-tolerance test between patients with and those without post-excisional hypoglycemia. The intraoperative immunoreactive insulin/glucose ratio was significantly higher in patients with hypoglycemia than in those without hypoglycemia. A higher 24-h urinary epinephrine level, but not norepinephrine level, was a predictive factor for post-excisional hypoglycemia. CONCLUSIONS: Post-excisional hypoglycemia is a frequent complication of pheochromocytoma resection, irrespective of the tumor location, and might be common in patients with epinephrine-predominant tumors. All patients undergoing resection of adrenal and extra-adrenal pheochromocytoma require intensive monitoring of serum glucose levels during and after surgery.

Impact of fluorodeoxyglucose uptake on positron emission tomography/computed tomography on chemosensitivity and survival in patients with metastatic urothelial carcinoma.

OBJECTIVES: To evaluate the impact of fluorodeoxyglucose uptake on positron emission tomography/computed tomography on chemosensitivity and survival in patients with metastatic urothelial carcinoma. METHODS: The present study assessed 51 metastatic urothelial carcinoma patients undergoing fluorodeoxyglucose positron emission tomography/computed tomography before first-line systemic chemotherapy. Fluorodeoxyglucose uptake in metastases was evaluated using the maximum standardized uptake value, which was measured for all eligible lesions, and the highest value among the maximum standardized uptake value measurements in each case was defined as the highest maximum standardized uptake value. The associations between the highest maximum standardized uptake value and objective response rate to chemotherapy, progression-free survival or cancer-specific survival were analyzed. For cancer-specific survival, the C-index was compared between multivariate models that incorporated predictors in the Bajorin model including the Karnofsky performance status and the presence of visceral metastasis, and the Apolo model additionally including hemoglobin and albumin levels, with/without the highest maximum standardized uptake value. RESULTS: The median age was 69 years. The Karnofsky performance status was ≥80% for all patients. Visceral metastasis was observed in 12 patients (24%). The objective response rate, median progression-free survival and median cancer-specific survival were 61%, 9 and 26 months in the entire cohort, respectively. The higher highest maximum standardized uptake value was significantly associated with a lower objective response rate, shorter progression-free survival and shorter cancer-specific survival (P = 0.01, <0.001 and 0.004, respectively). On multivariate analyses, the highest maximum standardized uptake value was an independent predictor for all end-points. In the multivariate models for cancer-specific survival, the C-index improved from 0.559 to 0.601 and from 0.604 to 0.652 by adding the highest maximum standardized uptake value to the parameter set of the Bajorin model and Apolo model, respectively. CONCLUSIONS: Higher fluorodeoxyglucose uptake in metastases was significantly and independently associated with poor chemosensitivity and worse survival outcomes. Fluorodeoxyglucose positron emission tomography/computed tomography might aid in patient counseling and treatment decisions for metastatic urothelial carcinoma patients.

Computer-aided diagnosis of prostate cancer on magnetic resonance imaging using a convolutional neural network algorithm.

OBJECTIVE: To develop a computer-aided diagnosis (CAD) algorithm with a deep learning architecture for detecting prostate cancer on magnetic resonance imaging (MRI) to promote global standardisation and diminish variation in the interpretation of prostate MRI. PATIENTS AND METHODS: We retrospectively reviewed data from 335 patients with a prostate-specific antigen level of <20 ng/mL who underwent MRI and extended systematic prostate biopsy with or without MRI-targeted biopsy. The data were divided into a training data set (n = 301), which was used to develop the CAD algorithm, and two evaluation data sets (n = 34). A deep convolutional neural network (CNN) was trained using MR images labelled as 'cancer' or 'no cancer' confirmed by the above-mentioned biopsy. Using the CAD algorithm that showed the best diagnostic accuracy with the two evaluation data sets, the data set not used for evaluation was analysed, and receiver operating curve analysis was performed. RESULTS: Graphics processing unit computing required 5.5 h to learn to analyse 2 million images. The time required for the CAD algorithm to evaluate a new image was 30 ms/image. The two algorithms showed area under the curve values of 0.645 and 0.636, respectively, in the validation data sets. The number of patients mistakenly diagnosed as having cancer was 16/17 patients and seven of 17 patients in the two validation data sets, respectively. Zero and two oversights were found in the two validation data sets, respectively. CONCLUSION: We developed a CAD system using a CNN algorithm for the fully automated detection of prostate cancer using MRI, which has the potential to provide reproducible interpretation and a greater level of standardisation and consistency.

Adherent Perinephric Fat in Asian Patients: Predictors and Impact on Perioperative Outcomes of Partial Nephrectomy.

INTRODUCTION: This study is aimed at evaluating the incidence and predictors of adherent perinephric fat (APF) in Asians during partial nephrectomy (PN), and determining the impact of APF on perioperative outcomes. MATERIALS AND METHODS: A total of 231 Asian patients with renal tumors underwent PN, and their Mayo adhesive probability (MAP) score was calculated. APF was intraoperatively determined, and the perioperative data were compared according to the presence of APF. The predictors of APF were examined using logistic regression analyses. RESULTS: APF was observed in 40 (17%) patients. In multivariate analysis, male gender and higher MAP score were the independent predictors of APF. The estimated blood loss was higher in patients with APF, however, the complication rates did not differ between the 2 groups. CONCLUSIONS: The MAP score can predict APF in an Asian population. The presence of APF was associated with greater blood loss; however it did not increase the postoperative complications in PN.

Prediction of Intraoperative Urinary Collecting System Entry in Patients with Peripheral Renal Tumors Undergoing Partial Nephrectomy: Usefulness of Tumor-Centered Multiplanar Reconstruction.

OBJECTIVE: To assess the usefulness of tumor-centered multiplanar reconstruction (TC-MPR) for predicting intraoperative urinary collecting system (UCS) entry in patients with peripheral renal tumors undergoing partial nephrectomy (PN). METHODS: Dynamic computed tomography images of 50 peripheral cT1 renal tumors treated with laparoendoscopic PN were analyzed. TC-MPR generated a digital cross-sectional image showing the tumor center and the closest calyx on a same plane. Patients and tumor characteristics including the distance from the tumor margin to the closest calyx (MPR-distance), and the angle formed by 2 tangent lines from the closest calyx to the tumor (MPR-angle) were assessed. RESULTS: Intraoperative UCS entry was observed in 15 patients (30%). The patients who experienced intraoperative UCS entry had a higher RENAL score, wider MPR-angle, and shorter MPR-distance than those who did not (p = 0.04, p = 0.001, p < 0.001, respectively). Multivariate analysis identified MPR-angle as an independent factor for intraoperative UCS entry (p < 0.001). CONCLUSIONS: The spatial information assessed using TC-MPR serves as a predictive factor for intraoperative UCS entry during PN.

Intensity ratio curve analysis of small renal masses on T2-weighted magnetic resonance imaging: Differentiation of fat-poor angiomyolipoma from renal cell carcinoma.

OBJECTIVES: To assess the diagnostic ability of a pixel intensity-based analysis in evaluating the magnetic resonance imaging characteristics of small renal masses, especially in differentiating fat-poor angiomyolipoma from renal cell carcinoma. METHODS: T2-weighted images from 121 solid small renal masses (<4 cm) without visible fat (14 fat-poor angiomyolipomas, 92 clear cell renal cell carcinomas, six chromophobe renal cell carcinomas and nine papillary renal cell carcinomas) were retrospectively evaluated. An intensity ratio curve was plotted using intensity ratios, which were ratios of signal intensities of tumor pixels (each pixel along a linear region of interest drawn across the renal tumor on T2-weighted image) to the signal intensity of a normal renal cortex. The diagnostic ability of the intensity ratio curve analysis was evaluated. RESULTS: The tumors were classified into three types: intensity ratio fat-poor angiomyolipoma (n = 19) with no pseudocapsule, iso-low intensity and no heterogeneity; intensity ratio clear cell renal cell carcinoma (n = 76) with a pseudocapsule, iso-high intensity and heterogeneity; and other type of intensity ratio (n = 26), including tumors that did not fall into the above two categories. The sensitivity/specificity/accuracy of the intensity ratio curve analysis in diagnosing fat-poor angiomyolipoma was 93%/94%/94%, respectively. When the intensity ratio curve analysis was applied only to the tumor with undetermined radiological diagnosis, the sensitivity for diagnosing fat-poor angiomyolipoma compared with subjective reading alone significantly improved (93% vs 50%; P = 0.014). CONCLUSIONS: Our novel semiquantitative model for combined assessment of key features of fat-poor angiomyolipoma, including low intensity, homogeneity and absence of a pseudocapsule on T2-weighted image, might make diagnosis of fat-poor angiomyolipoma more accurate.

Impact of the Prostate Imaging Reporting and Data System, Version 2, on MRI Diagnosis for Extracapsular Extension of Prostate Cancer.

OBJECTIVE: The purpose of this study is to validate the Prostate Imaging Reporting and Data System, version 2 (PI-RADSv2), in assessing extracapsular extension (ECE), compared with PI-RADS, version 1 (PI-RADSv1). MATERIALS AND METHODS: A total of 210 patients with clinically localized prostate cancer underwent MRI and radical prostatectomy. Two readers independently interpreted the MR images. In PI-RADSv1, 5-point ECE risk scoring was used. In PI-RADSv2, ECE criteria included morphologic features and a tumor-capsule contact length (CL) greater than 10 mm. The diagnostic performance of each PI-RADS version and the cutoff CL were evaluated. RESULTS: ECE was found in 56 patients (26.7%). In PI-RADSv1, maximal accuracy was achieved with a risk score of 3 or greater. At this threshold, positive findings on PI-RADSv1 and PI-RADSv2 were identified in 21.0-34.3% and 49.0-51.4% of patients, respectively. Compared with PI-RADSv1, PI-RADSv2 had higher negative predictive values (84.9-89.1% vs 96.3-97.1%, respectively; p = 0.003 and 0.021, for each reader). PI-RADSv1 and PI-RADSv2 had positive predictive values of 56.9-70.5% and 49.1-50.5%, respectively (p = 0.025 and 0.300, respectively). Interobserver kappa values for PI-RADSv1 and PI-RADSv2 were 0.511 and 0.781, respectively. The best cutoff CL was greater than 10 mm among patients without morphologic features of ECE. For patients positive for ECE on the basis of PI-RADSv2 but not PI-RADSv1, 73.3-74.1% of prostate cancer cases with a biopsy Gleason score of 7 or less and 35.7-44.4% of cases with a biopsy Gleason score of 8 or higher were overstaged. CONCLUSION: PI-RADSv2 reduces understaging and improves interobserver agreement in ECE assessment. However, overstaging is a concern, and the biopsy Gleason score may have a complementary role in reducing overstaging.

Early response of C-reactive protein as a predictor of survival in patients with metastatic renal cell carcinoma treated with tyrosine kinase inhibitors.

BACKGROUND: Pretreatment C-reactive protein (CRP) has been shown to be an independent prognostic factor for metastatic renal cell carcinoma (mRCC) treated with tyrosine kinase inhibitors (TKIs). We further evaluated the early response of CRP after the initiation of TKIs. METHODS: A total of 103 patients (80 men and 23 women) were treated with TKIs for mRCC from 2008-2013. Patients were divided into three groups according to their early CRP kinetics-patients whose baseline CRP levels were <10 mg/L (non-elevated), patients whose baseline CRP levels were ≥10 mg/L and had decreased by >20% at 4 weeks after the initiation of TKIs (early CRP responder), and the remaining patients (non-early CRP responder). The endpoints were progression-free survival (PFS) and overall survival (OS). RESULTS: The median follow-up period was 21 (interquartile range 10-34) months. The numbers of patients classified as non-elevated, early CRP responder, and non-early CRP responder were 62, 19, and 22, respectively. The 1-year PFS rates of patients in the non-elevated, early CRP responder, and non-early CRP responder groups were 50, 23, and 9.7%, respectively (p < 0.001). The 1-year OS rates of patients in these three groups were 79, 62, and 36%, respectively (p < 0.001). In multivariate analysis, the early CRP kinetics assessment was a significant independent factor for PFS and OS. CONCLUSIONS: Early CRP response at 4 weeks is predictive of survival for patients with mRCC treated with TKI.

Potential Utility of Diffusion-Weighted Magnetic Resonance Imaging in Diagnosis of Residual Bladder Cancer before Second Transurethral Resection.

INTRODUCTION: The study aimed to investigate the diagnostic utility of diffusion-weighted MRI (DW-MRI) in differentiating residual bladder cancer from benign postoperative changes before a second transurethral resection of the bladder (TURB). MATERIALS AND METHODS: Of the 75 bladder cancer patients who underwent a second TURB from 2013 to 2015, 23 patients who underwent multi-sequence bladder MRI after their initial TURB were retrospectively evaluated. Thirty lesions were histologically examined at the second TURB and the results of them were compared with the findings obtained through T2-weighted MRI, dynamic contrast-enhanced MRI (DCE-MRI), and DW-MRI. RESULTS: Positive findings of 27, 28, and 15 lesions showed up on T2W-, DCE-, and DW-MRI, respectively. Thirteen lesions were confirmed histologically to constitute residual cancer. The sensitivity/specificity/accuracy of T2W-, DCE-, and DW-MRI were 100/18/53, 100/12/50, and 92/82/87%, respectively. DW-MRI was significantly superior in specificity and accuracy to T2W- (p < 0.01 for both) and DCE-MRI (p < 0.01 for both). CONCLUSIONS: This study first showed the superiority of DW-MRI to T2W- and DCE-MRI in differentiating residual cancer before a second TURB.

Multitask Imaging Monitor for Surgical Navigation: Combination of Touchless Interface and Head-Mounted Display.

As a result of the dramatic improvements in the resolution, wearability, and weight of head-mounted displays (HMDs), they have become increasingly applied in the medical field as personal imaging monitors. The combined use of a multiplexer with an HMD allows the wearer to simultaneously and seamlessly monitor multiple streams of imaging information through the HMD. We developed a multitask imaging monitor for surgical navigation by combining a touchless surgical imaging control system with an HMD. This system is composed of a standard color digital video camera mounted on the HMD and computer software that enables the identification of the number of pictured fingertips from the video camera image. The HMD wearer uses this information as a touchless interface for the operating multiplexer, which can control the arrays and types of imaging information displayed on the HMD. We used this system in an experimental demonstration during a single-port gasless partial nephrectomy. The use of this multitask imaging monitor using a touchless interface would refine the surgical workflow, especially during surgical navigation.