Non-contrast Phase Research Articles

Abstract No. 682 Workup of GI bleeds: nuclear medicine vs. CT angiography

With an aging population acute gastrointestinal bleeding (GIB) requiring hospitalization and treatment continues to rise with an incidence of approximately 36/100,0001. The diagnostic imaging gold standard has historically been radionuclide labeled red blood cell scintigraphy (RBC scan) that has been able to detect bleeding rates as low as 0.1 ml/min2. However, RBC scans have several shortcomings such as preparation and scan time, technologist and equipment availability, and the requirement for relative hemodynamic stability for an extended time period. Additionally, RBC scans cannot identify other mimickers of GIB or provide anatomic detail. Given these limitations, our institution has begun employing triple phase CT angiography (CTA) as the initial, preferred diagnostic test for GIB, thought to have a minimum detectable bleeding rate of 0.35 ml/min3. Our institutional CTA GIB protocol requires no special patient preparation. Scanning is performed through the abdomen and pelvis starting with a non-contrast phase, followed by an arterial phase and finally a five-minute delay scan. As many of these GIB patients are critically ill and trend towards being hemodynamically unstable, the increased availability offered by CT scan is paramount for rapid treatment stratification. Since January 2017, over an 8-month time period, our institution performed a total of 31 RBC scans and 42 CTA GIB scans. The mean turnaround time from test initiation to release of a completed report was 208 minutes for RBC scans and 48 minutes for CTA GIB scans. RBC scans resulted in 38.7% (12/31) positive cases with six going onto catheter directed angiography. Conversely, 23.8% (10/42) of CTA GIB scans were positive and five proceeded to the interventional suite. RBC scans have been part of the diagnostic armamentarium since the 1970s and will continue to have a role in GIB management. However, given the tenuous clinical status of these patients, the speed, accuracy, and ubiquity of CTA will continue to grow. RBC scans and CTA GIB had the same rate (50%) of patients going onto mesenteric angiography. However, our results show that CTA’s reduced turnaround time to definitive therapy greatly impr

Attenuation values of renal parenchyma in virtual noncontrast images acquired from multiphase renal dual-energy CT: Comparison with standard noncontrast CT

ObjectivesTo compare the renal parenchyma attenuation of virtual noncontrast (VNC) images derived from multiphase renal dual-energy computed tomography (DECT) with standard noncontrast (SNC) images, and to determine the optimum phase for VNC images. Materials and methodsTwenty-nine men and 16 women (mean age, 61 ± 13 years; range, 37–89 years) underwent dynamic renal DECT (100/Sn140 kVp) were included in this institutional review board–approved retrospective study. There were four phases of the scan, which included noncontrast, corticomedullary (CMP), nephrographic (NP), and excretory phases (EP). The VNC images was generated from CMP, NP and EP. CT numbers of SNC images and VNC images of each phases were measured in the renal cortex and medulla. Mean standard deviation of subcutaneous fat was measured as image noise on SNC and VNC images. Radiation dose was recorded and potential radiation dose reduction was estimated. Results were tested for statistical significance using the unpaired t-test and agreement using Bland–Altman plot analysis. ResultsThe difference in mean attenuation between SNC and each phase of VNC images were ≤4 HU. The mean attenuation of renal cortex and medulla was 33.2 ± 4.4 HU, and 34.2 ± 4.8 HU in SNC, 33.6 ± 7.6 HU and 31.1 ± 8.3 HU in VNC of CMP, 34.8 ± 8.6 HU and 35.6 ± 8.5 HU in VNC of NP, 31.5 ± 7.6 HU and 32.4 ± 7.5 HU in VNC of EP. In VNC of CMP, the attenuation of the cortex was higher than the medulla (p < 0.05), and the attenuation of medulla was significant lower than that of SNC (p < 0.01). In VNC of NP, the attenuation of renal cortex was higher than SNC (p < 0.05). In VNC of EP, the attenuation of cortex and medulla were lower than SNC (p < 0.05), and inadequate iodine subtraction in collecting system was noted. Image noise was significantly greater in SNC (p < 0.001). Mean radiation dose reduction achievable by removing the SNC was 12.3% ± 0.9%. ConclusionsVNC images from multiphase renal DECT were similar to SNC images. Using the nephrographic phase can gives more comparable VNC images to SNC images in renal parenchyma than other phases.

Role of Contrast Enhancement and Corrected Attenuation Values of Renal Tumors in Predicting Renal Cell Carcinoma (RCC) Subtypes: Protocol for a Triphasic Multi-Slice Computed Tomography (CT) Procedure.

SummaryBackgroundTo distinguish RCC subtypes based on contrast enhancement features of CT images.Material/MethodsIn total, 59 lesions from 57 patients were included. All patients underwent multi-slice CT imaging with a triphasic protocol, which included non-contrast, corticomedullary, nephrographic and urographic phases. Contrast enhancement features of renal masses were evaluated in terms of CT attenuation values (AV) and differences in contrast density; the aorta or renal parenchyma were evaluated based on corrected or relative values.ResultsClear cell RCC (ccRCC) showed more intense contrast enhancement than other RCC subtypes. When differentiating ccRCC from other RCC subtypes, a cut-off AV of 86–89 HU, aorta-based corrected AV of 89–95 HU and renal parenchyma-based corrected AV of 87–95 HU showed a diagnostic accuracy of 81–86%, 86–88% and 74–78%, respectively, in the corticomedullary phase. Furthermore, a cutoff of 2.42–2.72 for the relative contrast enhancement ratio, a cutoff of 2.59–2.74 for the aorta-based corrected relative contrast enhancement ratio and a cutoff of 2.63–2.76 for the renal parenchyma-based attenuation ratio showed a diagnostic accuracy of 83–88%, 88–90% and 81%, respectively.ConclusionsThe most reliable parameters for differentiating ccRCC from other RCC subtypes are aorta-based corrected AV and aorta-based corrected relative contrast enhancement values in the corticomedullary phase.

Abstract WMP9: Real-World Outcomes of Patients Presenting with Acute Ischemic Stroke &gt;6 Hours Since Symptom Onset Treated With Endovascular Therapy

Introduction: Endovascular therapy(EVT) is proven effective for patients with acute ischemic stroke with proximal vessel occlusion, treated within 6 hours since symptom onset. However, up to 30% of stroke patients wake up with their symptoms (“wake-up stroke” (WUS)) or have an unknown time of onset. Canadian guidelines suggest that EVT may also be effective up to 12 hours after onset and yet-to-be published data from the DAWN trial also suggest a strong benefit of EVT for these patients if selected by perfusion imaging. We aimed to examine the real-world effectiveness of EVT in late-presenting stroke patients selected for EVT with a simple non-contrast CT (NCCT) and simple phase CT angiogram (CTA). Methods: We analyzed a prospectively collected registry of epidemiological, clinical and imaging data of patients treated for acute ischemic stroke ≥6 hours since symptom onset or WUS in a tertiary stroke center (Hôpital Notre-Dame, Montréal) between 2016 and 2017. Eligibility for EVT was based on a combination of disabling neurological deficit, a NCCT with salvageable brain tissue (ASPECTS &gt;5), and presence of a LVO on CTA. Results: Over a 16-month period, a total of 366 patients were treated with IV thrombolysis and/or EVT. Of these, 46 had WUS or presented ≥ 6 hours since symptom onset and received EVT. Median age was 70, median baseline mRS score 1, median NIHSS at arrival 17 and median ASPECTS 9. Good collaterals on CTA were noted in 63%(29) of patients. 5 patients had posterior circulation stroke with basilar occlusion. Median time from last time seen normal to admission was 9h17(IQR, 6h44-12h46). 31 (67.4%) NCCTs were done at a referent center and not repeated locally to avoid treatment delays. At 3-month follow-up, functional autonomy(mRS ≤ 2) was found in 15 (32.6%) patients while 15 (32,6%) died (mRS=6). Symptomatic hemorrhagic transformation occurred in 3(6.5%) patients. Conclusions: In a real-world setting, EVT is feasible in late-presenting stroke patients selected by NCCT and yields favorable outcomes similar to those seen in the more pragmatic EVT trials.

Quantifying Sarcopenia Reference Values Using Lumbar and Thoracic Muscle Areas in a Healthy Population.

Sarcopenia is defined as the loss of skeletal muscle mass and function associated with aging. Muscle mass can be reliably and accurately quantified using clinical CT scans but reference measurements are lacking, particularly in healthy US populations. Two-phase CT scans from healthy kidney donors (age 18-40) at the University of Michigan between 1999-2010 were utilized. Muscle mass was quantified using two thoracic and two lumbar muscle cross-sectional area (CSA) measures. Indexed measurements were computed as area divided by height-squared. Paired analyses of non-contrast and contrast phases and different Hounsfield Unit (HU) ranges for muscle were conducted to determine their effect on CSA muscle measures. We report the means, standard deviations, and 2SD sarcopenia cutoffs from this population. Healthy population CSA (cm2) cutoffs for N=604 males/females respectively were: 34.7/20.9 (T12 Dorsal Muscle), 91.5/55.9 (T12 Skeletal Muscle), 141.7/91.2 (L3 Skeletal Muscle), 23.5/14.3 (L4 Total Psoas Area), and 23.4/14.3 (L4 Psoas Muscle Area). Height-indexed CSA (cm2/m2) cutoffs for males/females respectively were: 10.9/7.8 (T12 Dorsal Muscle), 28.7/20.6 (T12 Skeletal Muscle), 44.6/34.0 (L3 Skeletal Muscle), 7.5/5.2 (L4 Total Psoas Area), and 7.4/5.2 (L4 Psoas Muscle Area). We confirmed that a mask of -29 to 150 HU is optimal and shows no significant difference between contrast-enhanced and non-contrast CT scan CSA measurements. We quantified reference values for lumbar and thoracic muscle CSA measures in a healthy US population. We defined the effect of IV contrast and different HU ranges for muscle. Combined, these results facilitate the extraction of clinically valuable data from the large numbers of existing scans performed for medical indications.

Subtraction computed tomography imaging to detect endoleaks after endovascular aneurysm sealing with sac anchoring.

Background Early detection of small type I endoleaks after endovascular aneurysm sealing is mandatory because they can rapidly progress and lead to severe complications. Recognition of endoleaks can be challenging due to the appearances on computed tomography unique to endovascular aneurysm sealing. We aimed to validate the accuracy and added value of subtraction computed tomography imaging using a post-processing software algorithm to improve detection of endovascular aneurysm sealing-associated endoleaks on postoperative surveillance imaging. Methods The computed tomography scans of 17 patients (16 males; median age: 78, range: 72-84) who underwent a post-endovascular aneurysm sealing computed tomography including both non-contrast and arterial phase series were used to validate the post processing software algorithm. Subtraction images are produced after segmentation and alignment. Initial alignment of the stent segmentations is automatically performed by registering the geometric centers of the 3D coordinates of both computed tomography series. Accurate alignment is then performed by translation with an iterative closest point algorithm. Accuracy of alignment was determined by calculating the root mean square error between matched 3D coordinates of stent segmentations. Results The median root mean square error after initial center of gravity alignment was 0.62 mm (IQR: 0.55-0.80 mm), which improved to 0.53 mm (IQR: 0.47-0.69 mm) after the ICP alignment. Visual inspection showed good alignment and no manual adjustment was necessary. Conclusions The possible merit of subtraction computed tomography imaging for the detection of small endoleaks during surveillance after endovascular aneurysm sealing was illustrated. Alignment of different computed tomography phases using a software algorithm was very accurate. Further studies are needed to establish the exact role of this technique during surveillance after endovascular aneurysm sealing compared to less invasive techniques like contrast-enhanced ultrasound.

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.

Comparison study of CT findings at different phases among pediatric hepatoblastoma patients based on PRETEXT system

Objective To compare the CT findings of different phases in pediatric hepatoblastoma (HB) based on PRETEXT system in order to optimize pediatric HB CT scan protocol. Methods A total of 58 HB patients who were surgical and pathological diagnosed from January 2015 to December 2016 were analyzed. Pre-operation CT exams were analyzed respectively. Observing items included tumor size, intra-abdominal invasion, bleeding, intrahepatic metastasis, lymphatic metastasis, metastasis (except lymphatic in abdomen) main portal vein, three main hepatic vein, inferior vena cava (IVC) invasion, para-tumor hepatic arteries, and its branches. All image findings were compared to pathological and surgical findings to calculate the agreement rate. Exact Fisher test and R×C χ2 test were used. Results According to the surgery and pathological results, the agreement rate of tumor size was n=40 (68.9%) at non-contrast phase, n=43 (74.1%) at artery phase and n=52 (91.2%) at venous phase. Venous phase was adaptive for observing tumor size (χ2=8.16, P=0.018). For main portal vein, three main hepatic vein, and IVC invasion, none was found at both non-contrast and artery phase. N=12 (20.7%, P<0.001) was found at venous phase. For para-tumor hepatic arteries, and its branches, none was found at non-contrast phase. N=46 (79.3%) was found at artery phase. N=17 (29.3%) was found at venous phase. Artery phase was adaptive for observing (P<0.001). There was no statistical significant difference in intrahepatic metastasis, lymphatic metastasis and metastasis. Conclusions Suspected pediatric HB, artery and venous phase CT scan would meet the clinical requirement, there was no need for non-contrast pahse. Follow up cases, a single venous phase was enough. Venous phase contributed much more information on tumor size and high risk prognosis evaluation. Key words: Child; Liver neoplsams; Tomography, X-ray computed; Radiation dosage

Body composition measurement using computed tomography: Does the phase of the scan matter?

The aim of this study was to determine, from the methodologic standpoint, the effect of the presence or absence of intravenous contrast on body composition variables obtained by analysis of computed tomography (CT) images. Triphasic abdominal (noncontrast, arterial phase, and portovenous phase contrast) CT scans from 111 patients were analyzed by two independent assessors at the third lumbar vertebral level using SliceOmatic software (version 5.0, TomoVision, Montreal, Canada). Variables included skeletal muscle index (SMI), fat and fat-free mass (FM and FFM, respectively), and mean skeletal muscle Hounsfield units (SMHU). Mean SMHU was lowest in the noncontrast phase (29.4, standard deviation [SD] 8.9 HU), followed by arterial (32.4, SD 9.3 HU) then portovenous phases (34.9, SD 9.4 HU). The mean skeletal muscle attenuation was significantly different depending on the phase of the scan in which the images were obtained. Calculated FM was significantly lower in both arterial (28.6, SD 8.8kg, P<0.0001) and portovenous phase scans (28.5, SD 8.9kg, P<0.0001) when compared with noncontrast (29.2, SD 8.9kg). The mean FFM was not significantly different as measured on noncontrast, arterial, or portovenous phase CT scans (48, SD 11.2; 48.1, SD 9.8; and 48.6, SD 10.2kg, respectively). No difference was seen in SMI. Interobserver reliability was high. The definition of myosteatosis should include a standardized phase of CT for analysis and this should be incorporated within its definition. However, as the magnitudes of the differences were relatively small, the effect of the phase of the scan on predicting outcome needs to be determined.

MP19-05 COMPUTERIZED SIMULATION OF FLUID DYNAMICS WITHIN THE RENAL COLLECTING SYSTEM AND THEIR ASSOCIATION WITH NEPHROLITHIASIS

You have accessJournal of UrologyStone Disease: Basic Research & Pathophysiology II1 Apr 2017MP19-05 COMPUTERIZED SIMULATION OF FLUID DYNAMICS WITHIN THE RENAL COLLECTING SYSTEM AND THEIR ASSOCIATION WITH NEPHROLITHIASIS Scott Wiener, Alexandros Mathioudakis, Phillip Smith, Marco Molina, Xinyu Zhao, and Erica Lambert Scott WienerScott Wiener More articles by this author , Alexandros MathioudakisAlexandros Mathioudakis More articles by this author , Phillip SmithPhillip Smith More articles by this author , Marco MolinaMarco Molina More articles by this author , Xinyu ZhaoXinyu Zhao More articles by this author , and Erica LambertErica Lambert More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2017.02.3247AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES The role of renal collecting system anatomy as it pertains to passage of stone material has been well studied, especially in the post-intervention setting. Current understanding of anatomic factors in the genesis of calculi is more limited, however. Here, we undertake the first computational fluid dynamic simulation of the renal collecting system in a known stone forming individual in order to correlate urine stagnation with calculogenesis. METHODS In this IRB exempt study, a CT urogram was 3D reconstructed from a patient with renal calculi attached to papillae. Computational fluid dynamics were performed to simulate flow within the collecting system assuming a urine production of 0.5 mL/s with “open” inlet conditions. The non-contrast phase of the CT scan was then compared to the simulated model in order to correlate simulated flowrate with stone location. RESULTS A 48-year-old first time stone former was identified with three renal calculi attached to papilla in three separate lower pole calyces. 3-D reconstruction identified stones in calyces which were labeled “5+6” (compound calyx), “8”, and “9”. Flow simulation produced relative volumetric flow rates for each calyx as follows: “3” - 29.38% of total, “7” - 20.10%, “1+10+2” - 16.76%, “8” - 16.61%, “9” - 8.75%, “5+6” - 7.85%, and “4” 0.55% . CONCLUSIONS The location of renal calculi appear to correlate with calyces with low flow rates. We offer this as supporting evidence to the idea that intrarenal anatomy plays a role in crystal retention and growth. Further work is required to perform more realistic urologic physiologic simulations. © 2017FiguresReferencesRelatedDetails Volume 197Issue 4SApril 2017Page: e230-e231 Advertisement Copyright & Permissions© 2017MetricsAuthor Information Scott Wiener More articles by this author Alexandros Mathioudakis More articles by this author Phillip Smith More articles by this author Marco Molina More articles by this author Xinyu Zhao More articles by this author Erica Lambert More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

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.

Likelihood of Incomplete Kidney Tumor Ablation with Radio Frequency Energy: Degree of Enhancement Matters

Larger size and clear cell histopathology are associated with worse outcomes for malignant renal tumors treated with radio frequency ablation. We hypothesize that greater tumor enhancement may be a risk factor for radio frequency ablation failure due to increased vascularity. A retrospective review of patients who underwent radio frequency ablation for renal tumors with contrast enhanced imaging available was performed. The change in Hounsfield units (HU) of the tumor from the noncontrast phase to the contrast enhanced arterial phase was calculated. Radio frequency ablation failure rates for biopsy confirmed malignant tumors were compared using the chi-squared test. Multivariate logistic analysis was performed to assess predictive variables for radio frequency ablation failure. Disease-free survival was calculated using Kaplan-Meier analysis. A total of 99 patients with biopsy confirmed malignant renal tumors and contrast enhanced imaging were identified. The incomplete ablation rate was significantly lower for tumors with enhancement less than 60 vs 60 HU or greater (0.0% vs 14.6%, p=0.005). On multivariate logistic regression analysis tumor enhancement 60 HU or greater (OR 1.14, p=0.008) remained a significant predictor of incomplete initial ablation. The 5-year disease-free survival for size less than 3 cm was 100% vs 69.2% for size 3 cm or greater (p <0.01), while 5-year disease-free survival for HU change less than 60 was 100% vs 92.4% for HU change 60 or greater (p=0.24). Biopsy confirmed malignant renal tumors, which exhibit a change in enhancement of 60 HU or greater, experience a higher rate of incomplete initial tumor ablation than tumors with enhancement less than 60 HU. Size 3 cm or greater portends worse 5-year disease-free survival after radio frequency ablation. The degree of enhancement should be considered when counseling patients before radio frequency ablation.

Is Non-Contrast CT Adequate for the Evaluation of Hepatic Metastasis in Patients Who Cannot Receive Iodinated Contrast Media?

ObjectiveTo evaluate the appropriateness of follow-up with only non-enhanced CT (NECT) in patients with gastrointestinal cancer.Subjects and MethodsThis retrospective study included 323 patients with colorectal and gastric cancer who underwent two consecutive CT examinations (CT1 and CT2), including non-contrast and portal venous phase CT images, with an interval of 1 year. Patients were divided into 2 groups: Group A included patients with no hepatic metastasis on CT1 and with or without newly developed metastasis on CT2 to evaluate the diagnostic performance of NECT for detecting newly developed hepatic metastasis; Group B included patients with known hepatic metastasis both on CT1 and CT2 to evaluate the accuracy of NECT for the assessment of hepatic metastasis based on RECIST criteria (version 1.1). Contrast-enhanced CT (CECT) images were considered as reference standards.ResultsGroup A included 172 patients (M:F = 107:65; mean age, 62.6 years). Among them, 57 patients had 95 metastases (mean size, 2.2 ± 1.3 cm). Per patient and per lesion sensitivity for diagnosing newly developed hepatic metastasis was 56.1–66.7% and 52.6–56.8%, respectively. In terms of small metastases (<1.5 cm), per lesion sensitivity was significantly decreased to 28.1–34.4% (P < 0.05). Metastasis size measurements were significantly smaller on NECT (P < 0.001) compared with reference standards. In Group B, the accuracy of response evaluation based on RECIST criteria was 65.6–72.2%.ConclusionsNECT showed inadequate diagnostic performances in both detecting newly developed hepatic metastasis and evaluating the response of hepatic metastasis based on RECIST criteria.

MP69-04 NUTRITIONAL SCREENING IS STRONGLY ASSOCIATED WITH OVERALL SURVIVAL IN PATIENTS TREATED WITH TARGETED AGENTS FOR ADVANCED RENAL CELL CARCINOMA

available at http://www.ncbi.nlm.nih.gov/pubmed/26901011 Editorial Comment: This study examined 137 renal masses without fat. All masses were smaller than 4 cm. Patients were scanned during the noncontrast and nephrographic phases (many also underwent corticomedullary imaging). A total of 117 renal cell carcinomas and 20 benign lesions were included. Of the 117 malignant masses 9 (8%) did not reach the 15 HU enhancement threshold on nephrographic imaging and 14 (12%) did not reach the 20 HU threshold. Clear cell, papillary and chromophobe lesions were identified as the hypoenhancing masses. As we closely scrutinize small renal lesions, enhancement is an important indicator of whether a lesion is solid or cystic. Some solid renal cell carcinomas may be hypoenhancing and overlap in the range with renal cysts that may show some artifactual pseudoenhancement. Radiologists must review the morphology of the small hypoenhancing mass, review prior studies and consult the patient electronic radiology jacket to see if other imaging (ultrasound or magnetic resonance) may assist in differentiating the subtle solid hypoenhancing lesion from a simple cyst, complicated cyst or high attenuation cyst.

204 Nutritional screening is strongly associated with overall survival in patients treated with targeted agents for advanced renal cell carcinoma

available at http://www.ncbi.nlm.nih.gov/pubmed/26901011 Editorial Comment: This study examined 137 renal masses without fat. All masses were smaller than 4 cm. Patients were scanned during the noncontrast and nephrographic phases (many also underwent corticomedullary imaging). A total of 117 renal cell carcinomas and 20 benign lesions were included. Of the 117 malignant masses 9 (8%) did not reach the 15 HU enhancement threshold on nephrographic imaging and 14 (12%) did not reach the 20 HU threshold. Clear cell, papillary and chromophobe lesions were identified as the hypoenhancing masses. As we closely scrutinize small renal lesions, enhancement is an important indicator of whether a lesion is solid or cystic. Some solid renal cell carcinomas may be hypoenhancing and overlap in the range with renal cysts that may show some artifactual pseudoenhancement. Radiologists must review the morphology of the small hypoenhancing mass, review prior studies and consult the patient electronic radiology jacket to see if other imaging (ultrasound or magnetic resonance) may assist in differentiating the subtle solid hypoenhancing lesion from a simple cyst, complicated cyst or high attenuation cyst.

Clinical values of of gemstone spectral CT in diagnosing thyroid disease.

To quantitatively evaluate the diagnostic value of gemstone spectral CT in thyroid disease. A total of 123 patients with thyroid diseases were enrolled in the retrospective study. All the patients underwent spectral CT scan, and 39 of them underwent dual-phase enhanced scan. Iodine concentration (IC) and normalized IC (NIC) were compared between benign and malignant nodules. The optimal threshold to predict malignancy was obtained by receiver operating characteristic curve (ROC). Multivariate ROC analysis was performed to evaluate the efficacy of combining the IC (NIC) and conventional morphological characteristics. Ten diffuse diseases and 113 nodular diseases were confirmed by clinical laboratory examination and histopathology. In total, 122 nodules (87 benign and 35 malignant) were detected, 41 nodules in enhanced cases. The IC and NIC<formula>_{VP}</formula> of malignant nodules were significantly lower than benign nodules in noncontrast and venous phase (VP) (P=0.000). The optimal IC and NIC<formula>_{VP}</formula> threshold was 0.68 mg/mL and 0.38, achieving 74.3% and 76.9% sensitivity, 66.7% and 80.0% specificity, respectively. For multivariate analysis, the area under ROC (AUC) was 0.88 and 0.94 in noncontrast and VP, respectively. Sensitivities of 77.1% and 84.6%, and specificities of 84.5% and 88.0% were achieved. Gemstone spectral CT can generally evaluate the abnormal iodine content in thyroid disease. Lower iodine can help differentiating malignant from benign nodules. A comprehensive analysis combining spectrum parameters and morphological characteristics is suggested in differential diagnosis.

Investigation on the value of spectral CT imaging in diagnosis of benign and malignant thyroid nodules

Objective To explore the value of gemstone spectral imaging (GSI) in the detection and differential diagnosis of benign and malignant thyroid nodules.Methods The spectral CT images in 88 patients with thyroid nodules were analyzed retrospectively.All the patients underwent spectral CT scanning,including 33 patients undergoing biphase enhanced CT imaging.Nodules were divided into benign and malignant ones according to histopathologic results.The iodine concentration,slope of spectral curve,effective atomic number in non-enhanced and enhanced scanning were compared between benign and malignant group by the Wilcoxon rank sum test,respectively.The optimal iodine concentration threshold to predict malignancy was obtained by receiver operating characteristic curve (ROC),sensitivity and specificity were achieved.Results A total of 106 nodules were detected,including 76 benign and 30 malignant nodules.In non-contrast CT imaging,the average iodine concentration,slope of spectral curve,effective atomic number of were 2.35 × 100 μg/ml,0.29 and 7.71 for benign group:-0.51 × 100 μg/ml,-0.06 and 7.52 for malignant group (Z value were-3.072,-3.107 and-3.055,respectively ; P ＜ 0.05).In the arterial phase,the average iodine concentration,slope of spectral curve,effective atomic number of the two group were 27.22 × 100 μg/ml,3.23 and 9.10 for benign group; 18.81 × 100 μg/ml,2.24 and 8.69 for malignant group (Z value were-2.582,-2.582 and-2.564,respectively; P ＜ 0.05).In venous phase,no significant difference was found for each parameter between the two groups (P ＞ 0.05).The optimal iodine concentration to predict malignancy was-0.35 × 100 μg/ml in non-enhanced phase with 56.7％ sensitivity and 73.7％ specificity.The optimal iodine concentration was 22.91 × 100 μg/ml in arterial phase,with 76.2％ sensitivity and 75.0％ specificity.Using iodine concentration to predict malignancy in both noncontrast phase and arterial phase,the sensitivity and specificity were 81.2％ and 73.3％,while the accuracy was 81.6％.Conclusion Gemstone spectral CT imaging can quantitatively evaluate the iodine content of thyroid nodules,having a potential value in differential diagnosis of thyroid nodules. Key words: Thyroid nodule ; Tomography, X-ray computed ; Comparative study

Imaging Follow-up of Endovascular Repair of Type B Aortic Dissection with Dual-Source, Dual-Energy CT and Late Delayed-Phase Scans

PurposeTo evaluate the diagnostic performance of dual-energy (DE) computed tomography (CT) after thoracic endovascular aortic repair (TEVAR) of type B dissection, and to investigate the value of late delayed (LD) acquisition in endoleak detection and false lumen patency assessment. Materials and MethodsTwenty-four patients with TEVAR for type B dissection underwent 53 tripe-phase CT examinations. Single-source unenhanced acquisition was followed by single-source arterial-phase and DE LD phase (300-s delay) imaging. Virtual noncontrast images were generated from DE acquisition. Two blinded radiologists retrospectively evaluated the cases in three reading sessions: session A (triphasic protocol), session B (virtual noncontrast and arterial phase), and session C (virtual noncontrast and arterial and LD phases). Endoleak detection accuracy during sessions B and C compared with session A (reference standard) was investigated. False lumen patency was assessed. Effective radiation dose was calculated. ResultsSession A revealed 37 endoleaks in 30 of 53 studies (56.6%). Session B revealed 31 of the 37 endoleaks, with one false-positive case, 83.8% sensitivity, 95.8% specificity, 79.3% negative predictive value, and 96.9% positive predictive value. Session C correctly depicted all 37 endoleaks, with one false-positive case, 100% sensitivity, 95.8% specificity, 100% negative predictive value, and 97.4% positive predictive value. Underestimation of false lumen patency was found in session B (P = .013). Virtual noncontrast imaging resulted in 17% radiation exposure reduction. ConclusionsVirtual noncontrast imaging can replace standard unenhanced images in follow-up after TEVAR of type B dissection, thus reducing radiation dose. Delayed-phase imaging is valuable in low-flow endoleaks detection and false lumen patency assessment.

Impact of size of region-of-interest on differentiation of renal cell carcinoma and renal cysts on multi-phase CT: Preliminary findings

IntroductionTo assess impact of size of regions-of-interest (ROI) on differentiation of RCC and renal cysts using multi-phase CT, with focus on differentiating papillary RCC (pRCC) and cysts given known hypovascularity of pRCC. Methods99 renal lesions (23 pRCC, 47 clear-cell RCC, 7 chromophobe RCC, 22 cysts) underwent multi-phase CT. Subjective presence of visual enhancement was recorded for each lesion. Whole-lesion (WL) ROIs, and small (≤5mm2), medium (average size of small and large ROIs), and large (half of lesion diameter) peripherally located partial-lesion (PL) ROIs, were placed on non-contrast and nephrographic phases. Impact of ROI size in separating cysts from all RCC and from pRCC based on increased attenuation between phases was assessed using ROC analysis. ResultsVisual enhancement was perceived in 96% of ccRCC, 61% of pRCC, and 9% of cysts. AUCs for separating all RCC and cysts for WL-ROI and small, medium, and large PL-ROIs were 91%, 96%, 91% and 93%, and among lesions without visible enhancement were 60%, 79%, 67% and 67%. AUCs for separating pRCC and cysts for WL-ROI and small, medium, and large PL-ROIs were 78%, 92%, 82% and 84%, and among lesions without visible enhancement were 64%, 88%, 69% and 69%. ConclusionSmall PL-ROIs had higher accuracy than WL-ROI or other PL-ROIs in separating RCC from cysts, with greater impact in differentiating pRCC from cysts and differentiating lesions without visible enhancement. Thus, when evaluating renal lesions using multi-phase CT, we suggest placing small peripheral ROIs for highest accuracy in distinguishing renal malignancy and benign cysts.

Dual Energy Computerized Tomography with a Split Bolus—A 1-Stop Shop for Patients with Suspected Urinary Stones?

We evaluated a dual energy, split bolus computerized tomography protocol that provides virtual noncontrast, parenchymal and urographic phases in a single scan. We assessed the sensitivity of the virtual noncontrast phase using this protocol to detect urinary stones compared to the gold standard of the true noncontrast phase. We prospectively enrolled in the study 81 patients who underwent unenhanced single energy computerized tomography at 120 kV/200 mA as well as contrast enhanced dual energy computerized tomography on a Somatom® Definition Flash-CT (tube A 80 kV/233 mA and tube B SN 140 kV/180 mA with 1/0.8 mm slice thickness). For the split bolus protocol 400 mg/ml Iomeron® were injected at 2 time points, that is 15 ml 10 minutes before the scan and 80 ml 65 seconds before the scan. In a consensus reading 2 readers evaluated the presence and diameter of stones on the true and virtual noncontrast phases. Of the 350 stones noted on the true noncontrast phase we found 289 on the virtual noncontrast phase as well as 13 false-positive and 66 false-negative stones. Sensitivity was 98.4%, 89.8% and 82.6% per patient, segment and stone, respectively. The diameter measured on the virtual noncontrast phase corresponded to a mean ± SD 92.5% ± 31.6% of the diameter on the true noncontrast phase. The mean effective dose was 4.8 ± 1.8 and 10.5 ± 3.7 mSv for the true and virtual noncontrast phases, respectively. The proposed protocol allows for combining 3 phases in a single scan while still enabling the detection of urinary stones at high sensitivity. This technique halves the radiation dose and provides the surgeon with better anatomical information on the calyceal system. Therefore, it is a valuable diagnostic tool for kidney stone treatment planning and followup.