Excretory Phase Research Articles

One-phase Split-bolus CT Urography – a Novel Approach To Reduce Radiation Dose in Diagnostics of Congenital Anomalies of Kidneys and Urinary Tract in Children

BackgroundLow-dose CT Urography (LD-CTU) has become a standard procedure in urinary tract abnormalities in children, especially when MR Urography is not available. Standard one-phase CTU is performed in excretory phase. There is also a split-bolus technique, which combines two or even three phases during one scan and provides more clinical information without higher radiation exposure. It can be implemented for congenital anomalies of kidneys and urinary tract (CAKUT) in children, however, this application is not deeply discussed in scientific literature. Aim of this publication is to present the protocol and determine the role of LD-CTU in diagnostic imaging of CAKUT in children.Material and methodsClose to 300 CTUs in children were performed as a standard of care during the last 6 years in our Department. Diagnostic accuracy in suspected CAKUT was analyzed, depending on applied protocol − standard excretory CTU, multiphase CTU and two different one-phase split-bolus CTU protocols.ResultsVisualization of the urinary tract was adequate in all study protocols. However, more clinically significant information was received in vascular-excretory protocol, including vascular and renal anatomy. Radiation exposure was similar or even lower than in other study protocols.ConclusionsOne-phase split-bolus CTU protocol is a novel approach in low-dose diagnostic imaging of CAKUT in children. Combination of vascular and excretory phases has been shown as very effective technique, especially in comprehensive anatomical assessment of the abnormality and qualification to surgical intervention.

Clinical Case of Urothelial Carcinoma with Implantation Metastasis

Urothelial cancer ranks 4th in the prevalence of malignant tumors after prostate cancer (or mammary glands), lung and colorectal cancer. Urothelial cancer of the upper urinary tract is quite rare and accounts for 5–10% of all cases of urothelial cancer. The leading clinical symptom of cancer of the renal pelvis and ureter is hematuria. Metastasis of tumors of the upper urinary tract is observed quite often. Metastasis of the tumor can be carried out lymphogenically into the para-aortic and parailiac lymph nodes, hematogenous to the liver, lungs, and bones. In addition, urothelial cancer often spreads through the urinary tract mucosa, mainly in the caudal direction. Currently, multidetector computer urography is considered the gold standard for examining the upper urinary tract, taking the place of excretory urography. This study should be performed under optimal conditions, especially with the inclusion of the excretory phase. It is necessary to perform scanning in a spiral mode (with a step of 1 millimeter) before and after the contrast medium. Clinical case of a patient with urethral carcinoma with implantation metastases in the ureter and in the bladder is presented.

Integration of CT urography improves diagnostic confidence of 68Ga-PSMA-11 PET/CT in prostate cancer patients

BackgroundTo prove the feasibility of integrating CT urography (CTU) into 68Ga-PSMA-11 PET/CT and to analyze the impact of CTU on assigning focal tracer accumulation in the ureteric space to either ureteric excretion or metastatic disease concerning topographic attribution and diagnostic confidence.MethodsTen prostate cancer patients who underwent 68Ga-PSMA-11 PET/CT including CTU because of biochemical relapse or known metastatic disease were retrospectively analyzed. CTU consisted of an excretory phase 10 min after injection of 80 mL iodinated contrast material. Ureter opacification at CTU was evaluated using the following score: 0, 0% opacification; 1, < 50%; 2, 50–99%; 3, 100%. Topographic attribution and confidence of topographic attribution of focal tracer accumulation in the ureteric space were separately assessed for 68Ga-PSMA-11 PET/CT without and with CTU. Diagnostic confidence was evaluated using the following score: 0, < 25% confidence; 1, 26–50%; 2, 51–75%; 3, 76–100%.ResultsAt CTU, mean ureter opacification score was 2.6 ± 0.7. At 68Ga-PSMA-11 PET/CT without CTU, mean confidence of topographic attribution of focal tracer accumulation was 2.5 ± 0.7 in total and 2.6 ± 0.7 for metastatic disease. At 68Ga-PSMA-11 PET/CT with CTU, mean confidence of topographic attribution of focal areas of tracer accumulation was significantly higher with 2.9 ± 0.2 in total and 2.7 ± 0.9 for metastatic disease (p < 0.001). In 4 of 34 findings (12%) attribution to either ureteric excretion or metastatic disease was discrepant between 68Ga-PSMA-11 PET/CT without and with CTU (n.s).ConclusionsIntegration of CTU into 68Ga-PSMA-11 PET/CT is feasible and increases diagnostic confidence of assigning focal areas of tracer accumulation in the ureteric space to either metastatic disease or ureteric excretion.

CT features of clear cell papillary renal cell carcinoma

Objective To investigate the computed tomography (CT) features of clear cell papillary renal cell carcinoma (CCPRCC). Methods The CT features of 6 patients with CCPRCC were analyzed retrospectively. The size, location, growth pattern, shape, texture, calcification, necrosis, hemorrhage, CT value, enhancement form and enhancement degree of the tumor and perirenal lymph nodes were observed. Results All 6 cases of CCPRCC were solitary lesions, of which 3 were located in the left kidney and 3 in the right kidney. Maximum tumor diameter ranged from 1.5 cm to 4.0 cm. The tumor margin was well-defined in 4 cases and ill-defined in two cases. All tumors showed expansive growth without invasion. There were three cases of endophytic growth and three cases of exophytic growth. Regarding tumor composition, only one case was cystic and the other five cases were solid. No calcification, necrosis and hemorrhage occurred in all the tumors. The CT value of tumors in unenhanced phase ranged from 31.2 HU to 42.5 HU. During the enhanced CT scan, 5 cases showed highly enhancement and 1 case showed moderate enhance-ment. The CT value of tumors in corticomedullary phase ranged from 75.1 HU to 150.1 HU. In nephrographic phase, the enhancement degree in 1 case continued to increase, but it decreased in the other 5 cases. The CT value ranged from 73.3 HU to 102.2 HU. The enhancement degree in all 6 cases decreased in excretory phase and the CT value ranged from 52.6 HU to 79.1 HU. In the aspect of tumor enhancement form, only one case showed homogeneous enhancement and the other five cases showed heterogeneous enhancement. In addition, the peripheral renal lymph nodes were not enlarged in all patients, and no tumor invasion or tumor thrombus formation occurred in the renal vein. Conclusions CCPRCC has a relatively specific CT features that are easily distinguished from papillary renal cell carcinoma or chromophobe renal cell carcinoma, but it is difficult to identify from early-stage clear cell renal cell carcinoma. Key words: Adenocarcinoma, clear cell; Carcinoma, renal cell/RA; Tomography, X-ray computed

Evaluation and Management of Non-iatrogenic Ureteral Trauma

Ureteral injuries are rare and represent a minority of genitourinary injuries in trauma patients. Their association with complex polytrauma and propensity for delayed recognition present diagnostic and therapeutic challenges. Herein, we present a review of the available literature on the evaluation and management of non-iatrogenic ureteral injuries. The incidence of traumatic ureteral injury appears to be increasing as a result of improved trauma survivability and enhanced imaging techniques. While most of the ureteral trauma literature reports on penetrating mechanisms of injury, blunt ureteral injuries are typically associated with more severe injury scores. Diagnosing traumatic ureteral injuries continues to be challenging and clinical suspicion should guide subsequent evaluation based on the patient’s condition. Computerized tomography with intravenous contrast and excretory phase imaging is the gold standard for evaluating suspected ureteral injuries in clinically stable trauma patients. Many ureteral injuries will still be diagnosed intraoperatively and may be successfully temporized or definitively reconstructed acutely. In unstable patients, damage control principles have been adapted to ureteral trauma permitting delayed reconstruction. Delayed diagnosis of these injuries has been associated with increased morbidity, mortality, length of stay, and renal loss. Traumatic ureteral injuries are rare and require a high index of suspicion. Patient physiology may guide the evaluation and eventual treatment of these injuries. Improved detection, management, and vigilance for potential complications of traumatic ureteral injuries can improve patient outcomes and decreased resource utilization.

Diagnostic value of 64-slice spiral computed tomography imaging of the urinary tract during the excretory phase for urinary tract obstruction.

The present study aimed to assess the diagnostic value of 64-slice spiral computed tomography (CT) imaging of the urinary tract during the excretory phase for urinary tract obstruction. CT imaging of the urinary tract during the excretory phase was performed in 46 patients that had been diagnosed with urinary tract obstruction by B-mode ultrasound imaging or clinical manifestations. It was demonstrated that out of the 46 patients, 18 had pelvic and ureteral calculi, 12 cases had congenital malformations, 3 had ureteral stricture caused by urinary tract infection and 13 cases had malignant tumors of the urinary tract. The average X-ray dose planned for the standard CT scan of the urinary tract group 1 was 14.11±5.45 mSv, while the actual X-ray dose administered for the CT scan during the excretory phase group 2 was 9.01±4.56 mSv. The difference between the two groups was statistically significant (t=15.36; P<0.01). The results of the present study indicate that CT scanning of the urinary tract during the excretory phase has a high diagnostic value for urinary tract obstruction.

Synergistic Antihyperlipidemic Activity of Salacia oblonga, Salacia roxbhurgii and Lagerstroemia parviflora

The present study aimed that evaluation antihyperlipidemic activity of Salacia oblonga, Salacia roxbhurgii and Lagerstroemia parviflora individually and combined plants extracted poly herbal extraction and screened for phytochemical study performed Preliminary Phytochemical analysis of crude extracts for Salacia oblonga, Salacia roxbhurgii and Lagerstroemia parviflora for Antihyperlipidemic activity by Triton X 100 Induced Hyperlipidemia model, High Fat Diet (FD) induced hyperlipidemic model, by estimating the Total Cholesterol, Triglycerides, HDL-C, LDL-C, VLDL-C. Phytochemical investigation reveals the presence of alkaloids, flavanoids, saponins, tannins, steroids, triterpinoids, carbohydrates and glycosides in poly herbal methanolic extraction and individual plant extraction, In acute toxicity studies no mortality was observed with either of the extracts even at the dose level of 2000mg/kg body weight. In the present study, the methanol extracts of three plants reduced (Total Cholesterol, Triglycerides, LDL-C, VLDL-C reduced significantly in poly herbal extraction when compared with individual extraction HDL-C was increased in poly herbal extraction) the cholesterol and triglycerides in a manner similar to the reduction facilitated by atorvastatin. The hypolipidemic activities of atorvastatin and the methanol extract of individual and polyherbal extraction were evident in both synthesis and excretory phases of triton-induced hyperlipidemia in rats.

CT urography: principles and indications

CT urography (CTU) is an imaging method tailored specifically for the evaluation of the upper urothelial tract and urinary bladder. High diagnostic accuracy in detecting primary and recurrent urothelial tumours, their differentiation from benign lesions, anatomic variation and malformation characterization, and evaluation of important pathology in the surrounding tissues, renders CTU a valuable imaging study of the urothelial tract. Haematuria, initial staging and post treatment follow up of upper urinary tract and bladder malignancies are the most important indications for CTU. Triple phase and split bolus techniques are most commonly used CTU protocols that consist of a non-contrast, nephrographic, and excretory phase, obtained by three or two acquisitions. CTU scanning protocols are tailored to achieve adequate image quality with optimal opacification and distension of the urinary tract at the lowest achievable radiation dose within the range of 5-15 mSv, comparable to the doses of intravenous urography. Detailed patient history, clinical examination, and urine analysis are essential for proper patient selection and targeted CTU protocol, which are the most important tools for increasing diagnostic accuracy and lowering patient radiation dose of CT urography.

Bladder cancer diagnosis with CT urography: test characteristics and reasons for false-positive and false-negative results.

To determine test characteristics of CT urography for detecting bladder cancer in patients with hematuria and those undergoing surveillance, and to analyze reasons for false-positive and false-negative results. A HIPAA-compliant, IRB-approved retrospective review of reports from 1623 CT urograms between 10/2010 and 12/31/2013 was performed. 710 examinations for hematuria or bladder cancer history were compared to cystoscopy performed within 6months. Reference standard was surgical pathology or 1-year minimum clinical follow-up. False-positive and false-negative examinations were reviewed to determine reasons for errors. Ninety-five bladder cancers were detected. CT urography accuracy: was 91.5% (650/710), sensitivity 86.3% (82/95), specificity 92.4% (568/615), positive predictive value 63.6% (82/129), and negative predictive value was 97.8% (568/581). Of 43 false positives, the majority of interpretation errors were due to benign prostatic hyperplasia (n=12), trabeculated bladder (n=9), and treatment changes (n=8). Other causes include blood clots, mistaken normal anatomy, infectious/inflammatory changes, or had no cystoscopic correlate. Of 13 false negatives, 11 were due to technique, one to a large urinary residual, one to artifact. There were no errors in perception. CT urography is an accurate test for diagnosing bladder cancer; however, in protocols relying predominantly on excretory phase images, overall sensitivity remains insufficient to obviate cystoscopy. Awareness of bladder cancer mimics may reduce false-positive results. Improvements in CTU technique may reduce false-negative results.

A comparison of radiation dose in single and split bolus multidetector computed tomography urography

Introduction: Routine multidetector computed tomography (MDCT) urography protocols include three phase scan with single bolus contrast material injection. To reduce the radiation dose a split bolus MDCT urography technique has been introduced. Methods: Nephrographic phase in single bolus was obtained by injecting 90 ml of Ioversol (Optiray320mgI/ml) contrast at the rate of 3ml/s during the preset time of 90 second. The excretory phase was taken at the delay of 10 minutes after the contrast injection. For split bolus only two phases (unenhanced and combined) were scanned from the diaphragm to the base of the urinary bladder. The combined phase in split bolus was performed by injecting the contrast in two bolus in which 40 ml at 2ml/s was injected in the first bolus and after a delay of 9 minutes, 60 ml at a rate of 3ml/s was injected, then the scan was obtained 90 second after the second bolus. The volume CT dose index (CTDIvol) and CT dose length product (CTDLP) were assessed in CT work station. Results: The mean effective radiation dose for single bolus MDCT urography was 40.5% more than the split bolus MDCT urography. Conclusion: Split bolus MDCT urography protocol was significantly better in effective radiation dose reduction compared with the single bolus MDCT urography protocol.

Assessment of the ability of CT urography with low-dose multi-phasic excretory phases for opacification of the urinary system.

ObjectiveTo prospectively evaluate the ability of CT urography with a low-dose multi-phasic excretory phase for opacification of the urinary system.Materials and methodsThirty-two patients underwent CT urography with low-dose multi-phasic s using adaptive iterative dose reduction 3D acquired at 5-, 10-, and 15-minute delays. Opacification scores of the upper urinary tracts and the urinary bladder were assigned for each excretory phase by two radiologists, who recorded whether adequate (>75%) or complete (100%) opacification of the upper urinary tract and urinary bladder was achieved in each patient. Adequate and complete opacification rates of the upper urinary tracts and the urinary bladder were compared among three excretory phases and among combined multi-phasic excretory phases using Cochran's Q test.ResultsThere was no significant difference among three excretory phases with 5-, 10-, and 15-minute delays in adequate (56.3, 43.8, and 63.5%, respectively; P = 0.174) and complete opacification rates (9.3, 15.6, and 18.7%, respectively; P = 0.417) of the upper urinary tracts. Combined tri-phasic excretory phases significantly improved adequate and complete opacification rates to 84.4% and 43.8%, respectively (P = 0.002). In contrast, there were significant differences among three excretory phases for the rate of adequate (31.3, 84.4, and 93.8%, respectively; P<0.001) and complete opacification (21.9, 53.1, and 81.3%, respectively; P<0.001) of the urinary bladder. Multi-phasic excretory phases did not improve these rates because opacification was always better with a longer delay.ConclusionAlthough multi-phasic acquisition of excretory phases is effective at improving opacification of the upper urinary tracts, complete opacification is difficult even with tri-phasic acquisition.

PD63-02 COMPLIANCE WITH AUA GUIDELINES WITH EXCRETORY PHASE IMAGING FOR EVALUATION OF HIGH-GRADE RENAL TRAUMA: RESULTS FROM THE AMERICAN ASSOCIATION FOR SURGERY OF TRAUMA (AAST) GENITOURINARY TRAUMA STUDY

PD63-02 COMPLIANCE WITH AUA GUIDELINES WITH EXCRETORY PHASE IMAGING FOR EVALUATION OF HIGH-GRADE RENAL TRAUMA: RESULTS FROM THE AMERICAN ASSOCIATION FOR SURGERY OF TRAUMA (AAST) GENITOURINARY TRAUMA STUDY

Type 1 papillary renal cell carcinoma: differentiation from Type 2 papillary RCC on multiphasic MDCT.

To investigate whether multiphasic MDCT enhancement can help differentiate type 1 papillary renal cell carcinoma (RCC) from type 2 papillary RCC. With IRB approval for this HIPAA-compliant retrospective study, we derived a cohort of 36 type 1 papillary RCCs and 33 type 2 papillary RCCs with preoperative multiphasic MDCT with up to four phases (unenhanced, corticomedullary, nephrographic, and excretory) from 2000 to 2013. Following segmentation, a computer-assisted detection (CAD) algorithm selected a 0.5cm-diameter region of maximal attenuation within each lesion in each phase; a 0.5cm-diameter region of interest was manually placed on uninvolved renal cortex in each phase. The relative attenuation of each lesion was calculated as [(Lesion attenuation-cortex attenuation)/cortex attenuation]×100. Absolute and relative attenuation values were compared using Mann-Whitney tests with Bonferroni correction for multiple comparisons. Relative excretory phase attenuation of type 2 papillary RCCs was significantly greater than that of type 1 papillary RCCs (2.0 vs. -18.3, p=0.005). Relative excretory phase attenuation differentiated type 1 papillary RCCs from type 2 papillary RCCs with an accuracy of 73% (36/49), sensitivity of 87% (26/30), positive predictive value of 74% (26/35), and negative predictive value of 71% (10/14). Multiphasic MDCT enhancement may assist in differentiating type 1 papillary RCCs from type 2 papillary RCCs, if prospectively validated.

Aorta-Lesion-Attenuation-Difference (ALAD) on contrast-enhanced CT: a potential imaging biomarker for differentiating malignant from benign oncocytic neoplasms.

To evaluate whether the Aorta-Lesion-Attenuation-Difference on contrast-enhanced CT can aid in the differentiation of malignant and benign oncocytic renal neoplasms. Two independent cohorts-an initial (biopsy) dataset and a validation (surgical) dataset-with oncocytomas and chromophobe renal cell carcinomas (chRCC) were included in this IRB-approved retrospective study. A region of interest was placed on the renal mass and abdominal aorta on the same CT image slice to calculate an Aorta-Lesion-Attenuation-Difference (ALAD). ROC curves were plotted for different enhancement phases, and diagnostic performance of ALAD for differentiating chRCC from oncocytomas was calculated. Seventy-nine renal masses (56 oncocytomas, 23 chRCC) were analyzed in the initial (biopsy) dataset. Thirty-six renal masses (16 oncocytomas, 20 chRCC) were reviewed in the validation (surgical) cohort. ALAD showed a statistically significant difference between oncocytomas and chromophobes during the nephrographic phase (p<0.001), early excretory phase (p<0.001), and excretory phase (p=0.029). The area under the ROC curve for the nephrographic phase was 1.00 (95% CI: 1.00-1.00) for the biopsy dataset and showed the narrowest confidence interval. At a threshold value of 25.5 HU, sensitivity was 100 (82.2%-100%) and specificity was 81.5 (61.9%-93.7%). When tested on the validation dataset on measurements made by an independent reader, the AUROC was 0.93 (95% CI: 0.84-1.00) with a sensitivity of 100 (80.0%-100%) and a specificity of 87.5 (60.4%-97.8%). Nephrographic phase ALAD has potential to differentiate benign and malignant oncocytic renal neoplasms on contrast-enhanced CT if histologic evaluation on biopsy is indeterminate.

Contrast-Enhanced Magnetic Resonance Cholangiography: Practical Tips and Clinical Indications for Biliary Disease Management.

Since its introduction, MRCP has been improved over the years due to the introduction of several technical advances and innovations. It consists of a noninvasive method for biliary tree representation, based on heavily T2-weighted images. Conventionally, its protocol includes two-dimensional single-shot fast spin-echo images, acquired with thin sections or with multiple thick slabs. In recent years, three-dimensional T2-weighted fast-recovery fast spin-echo images have been added to the conventional protocol, increasing the possibility of biliary anatomy demonstration and leading to a significant benefit over conventional 2D imaging. A significant innovation has been reached with the introduction of hepatobiliary contrasts, represented by gadoxetic acid and gadobenate dimeglumine: they are excreted into the bile canaliculi, allowing the opacification of the biliary tree. Recently, 3D interpolated T1-weighted spoiled gradient echo images have been proposed for the evaluation of the biliary tree, obtaining images after hepatobiliary contrast agent administration. Thus, the acquisition of these excretory phases improves the diagnostic capability of conventional MRCP—based on T2 acquisitions. In this paper, technical features of contrast-enhanced magnetic resonance cholangiography are briefly discussed; main diagnostic tips of hepatobiliary phase are showed, emphasizing the benefit of enhanced cholangiography in comparison with conventional MRCP.

Are the unenhanced and excretory CT phases necessary for the evaluation of acute pyelonephritis?

Background The most widely accepted computed tomography (CT) protocol for diagnosis of acute pyelonephritis (APN) includes at least a pre- and post-contrast scan, which may expose patients to higher doses of ionizing radiation. Purpose To establish the accuracy, reproducibility, and degree of confidence in CT diagnosis of acute pyelonephritis (APN) and urolithiasis using only images obtained during the nephrographic phase. Material and Methods A retrospective study of 100 consecutive patients (88 women; age range, 19-70 years) with clinical and laboratory suspicion of APN and who underwent triphasic abdominal CT scans (non-contrast, nephrographic, and excretory phases) was performed. Two readers first evaluated independently only the nephrographic phase of scans, and, in a second session, the entire study. The diagnostic reference standard was settled by a third experienced radiologist who reviewed all triphasic scans and clinical data. Results The accuracy of only nephrographic phase for diagnosis of APN and urolithiasis was in the range of 90.3-91.78% and 96.27-99.25%, respectively. There was no significant difference in comparison with the triphasic reading (z: -0.4 - 0.2; P = 0.34-0.83). The average degree of confidence for APN also showed no significant variation for both readers ( P = 0.4 and 0.08). Almost perfect inter-observer agreements for the diagnosis of APN (k = 0.86, P < 0.001) and for urolithiasis (k = 0.84, P < 0.001) were observed when considering only the nephrographic phase. Conclusion CT assessment of APN and urolithiasis can be accurately performed using only the late nephrographic phase, with consequent dose reduction.

Voxel-based whole-lesion enhancement parameters: a study of its clinical value in differentiating clear cell renal cell carcinoma from renal oncocytoma.

The purpose of this study was to compare whole-lesion (WL) enhancement parameters to single region of interest (ROI)-based enhancement in discriminating clear cell renal cell carcinoma (ccRCC) from renal oncocytoma. In this IRB-approved retrospective study, the surgical database was queried to derive a cohort of 94 postnephrectomy patients with ccRCC or oncocytoma (68 ccRCC, 26 oncocytoma), who underwent preoperative multiphase contrast-enhanced computed tomography (CECT) between June 2009 and August 2013. CT acquisitions were transferred to a three-dimensional workstation, and WL ROIs were manually segmented. WL enhancement and histogram distribution parameters skewness, kurtosis, standard deviation (SD), and interquartile range (IQR) were calculated. WL enhancement parameters were compared to single ROI-based enhancement using receiver operating characteristic (ROC) analysis. Oncocytoma had significantly higher WL enhancement than ccRCC in nephrographic (mean, p=0.02; median, p=0.03) and excretory phases (mean, p=0.03; median p<0.01). ccRCC had significantly higher kurtosis than oncocytoma in corticomedullary (p=0.03) and excretory phases (p<0.01), and significantly higher SD and IQR than oncocytoma in all postcontrast phases: corticomedullary (SD, p=0.02; IQR, p<0.01), nephrographic (SD, p=0.01; IQR, p=0.03), and excretory (SD, p<0.01; IQR, p<0.01). When compared to single ROI-based enhancement, WL enhancement alone did not demonstrate a statistical advantage in discriminating between ccRCC and oncocytoma (area under ROC curve of 0.78 and 0.72 respectively), but when combined with histogram distribution parameters (area under ROC curve of 0.86), it did demonstrate a slight improvement. Our study suggests that voxel-based WL enhancement parameters provide only a slight improvement over single ROI-based enhancement techniques in differentiating between ccRCC and renal oncocytoma.

Utility of virtual unenhanced images and split-bolus injection using spectral multidetector CT for the assessment of renal cell carcinoma conspicuity and radiation dose.

The aim of this study was to evaluate the radiation dose and renal cell carcinoma conspicuity with virtual unenhanced images and split-bolus injection from spectral multidetector CT (MDCT). This prospective study was approved by the Ethics Committee, and informed consent was obtained. Ninety suspected patients of renal cell carcinoma diagnosed by abdominal ultrasonography and CEUS were randomly divided into two groups by a radiographer. Patients of the first group underwent spectral MDCT with virtual unenhanced imaging and split-bolus injection, while patients in the second group underwent conventional unenhanced as well as tri-phasic enhanced CT. Group A (split-bolus spectral MDCT group): The contrast material was administered at a dose of 1.5mL/kg body weight at a flow rate of 4mL/s, with a ratio of 7 to 5 before the CT scan with an interval of 60seconds. Virtual unenhanced images were generated using a standard three-material decomposition algorithm, and the best mono-energy (keV) was calculated to show the tumour, renal artery and renal vein. Group B (conventional tri-phasic enhanced CT group): the contrast agent was injected with a dose of 1.5mL/kg body weight at a flow rate of 4mL/s. The corticomedullary phase scanning was performed once the arterial CT value reached 100 HU; the nephrographic phase was scanned 60seconds later. And the excretory phase was scanned 5min after onset of contrast injection. The LKR (lesion kidney ratio), CNR, and CT value of the corticomedullary and nephrographic phase were measured. The opacification of the renal collection system (including calices, infundibula and renal pelvis) was scored. The radiation dose was recorded. Statistical analysis was performed using Student's t-test, Fisher's exact test, the Mann-Whitney U-test, and k statistics. There were no statistically significant differences between the two groups in age, sex and body mass index (BMI), but there was significant difference in treatment methods. The best mono-energy was 58keV for showing the tumour and renal artery and 67keV for showing the renal vein. There were no differences in the mean attenuations of normal renal parenchyma, renal tumour, CNR, and imaging quality between true unenhanced images and virtual unenhanced images from the combined corticomedullary and nephrographic phase. The LKR of the mono-energy at 58keV from the combined corticomedullary and nephrographic phase was significantly better than the corticomedullary phase of the conventional enhanced CT scan (0.74±0.18 vs 1.08±0.34, P<.01), but there was no difference in CNR (2.31±1.74 vs 2.79±1.83, P>.05). There were no differences in the CT values of the renal tumour, normal renal parenchyma and renal artery between the two groups (P>.05). The CT value of the renal vein at mono-energy (67keV) (200.55±43.38) from the combined corticomedullary and nephrographic phase was higher than the conventional CT scan (140.90±42.64) in the nephrographic phase. The Kappa scores of the rate of the renal collection system for the conventional CT and spectral CT were 0.68 (95% confidence interval [CI]: 0.35-0.89) and 0.54 (95% CI: 0.30-0.88), respectively. The radiation dose (735±162mGy·cm) of Group A was significantly less than that of Group B (1032±324mGy·cm) (P<.01). Conspicuity with virtual unenhanced imaging and split-bolus injection from spectral multidetector CT is better than or equal to the conventional three-phase enhanced CT scan in showing the RCC, renal artery and renal vein, while the radiation dose can be reduced by 28.78%.

Determination of Glomerular Filtration Rate with CT Measurement of Renal Clearance of Iodinated Contrast Material versus 99mTc-DTPA Dynamic Imaging "Gates" Method: A Validation Study in Asymmetrical Renal Disease.

Purpose To validate a computed tomographic (CT) glomerular filtration rate (GFR) measurement and compare it with renal dynamic imaging GFR obtained by using the "Gates" method, with dual plasma sampling technetium 99m (99mTc) diethylenetriaminepenta-acetic acid (DTPA) clearance ("true GFR") as the reference standard. Materials and Methods This prospective study was approved by the institutional review board, and written informed consent was obtained from all patients. Forty-two patients with unilateral renal disease were included. Single-kidney CT GFR was calculated as excretory phase whole-kidney CT number enhancement divided by the area under the time-attenuation curve for the aorta, multiplied by (1 - hematocrit level). The CT GFR was then obtained by summing the result of the two sides. The true GFR and the Gates GFR were measured by using a single injection of 99mTc-DTPA. The CT GFR and Gates GFR were respectively compared with the true GFR by using a paired t test and linear regression analysis. Results The difference between CT GFR (mean ± standard deviation, 96.02 mL/min ± 23.11) and true GFR (90.50 mL/min ± 21.46) was 5.51 mL/min ± 6.96 (P < .001), demonstrating 6.09% systemic overestimation. The difference between Gates GFR (93.93 mL/min ± 26.97) and true GFR was 3.42 mL/min ± 16.10 (P = .176). Linear regression findings confirmed the association between CT GFR (y-axis) and true GFR (x-axis) and between Gates GFR (y-axis) and true GFR (x-axis) (P < .001 for both). Both regression lines paralleled the diagonal (intercept = 0 and slope = 1) (P = .599 and P = .945, respectively). The 95% confidence interval of the former was above the diagonal, confirming the systemic overestimation. The standard deviations of residuals of both linear regressions were 7.02 mL/min and 16.30 mL/min, respectively, demonstrating smaller deviation of the CT GFR (P < .001). Conclusion The proposed CT GFR measurement was validated in this study and was proved to be more accurate than the Gates method despite slight (6.09%) systemic overestimation. © RSNA, 2016 Online supplemental material is available for this article.

Clear cell renal cell carcinoma: identifying the gain of chromosome 12 on multiphasic MDCT.

To determine whether multiphasic MDCT enhancement can help identify the gain of chromosome 12 in clear cell renal cell carcinomas (RCCs). With IRB approval for this HIPAA-compliant case control study, we derived a cohort of 65 clear cell RCCs with preoperative four-phase renal mass MDCT from October 2000 to August 2013. Each lesion was segmented in its entirety on axial images in all phases. A computer-assisted detection (CAD) algorithm selected a 0.5-cm-diameter region of maximal attenuation within each lesion in each phase. Attenuation in each phase between clear cell RCCs with and without the gain of 12 was compared using t-tests. While the entire cohort of clear cell RCCs exhibited peak enhancement in the corticomedullary phase, the subcohort of lesions with the gain of 12 exhibited significantly greater enhancement in the nephrographic (179 vs. 145HU, p=0.004) and excretory phases (147 vs. 118HU, p=0.004) than the subcohort of lesions without the gain of 12. A nephrographic threshold of 186HU identified the gain of 12 with an accuracy of 86% (56/65), specificity of 93% (51/55), and negative predictive value of 91% (51/56). Multiphasic MDCT enhancement, specifically enhancement in the nephrographic and excretory phases, may potentially assist in identifying the gain of 12 in clear cell RCCs.