Imaging for Early Detection of Pancreatic Ductal Adenocarcinoma: Updates and Challenges in the Implementation of Screening and Surveillance Programs.

Pancreatic ductal adenocarcinoma (PDA) is one of the most aggressive cancers. It has a poor 5-year survival rate of 12%, partly because most cases are diagnosed at advanced stages, precluding curative surgical resection. Early-stage PDA has significantly better prognoses due to increased potential for curative interventions, making early detection of PDA critically important to improved patient outcomes. We examine current and evolving early detection concepts, screening strategies, diagnostic yields among high-risk individuals, controversies, and limitations of standard-of-care imaging.

Recent developments in the design of functional derivatives of edaravone and exploration of their antioxidant activities.

Edaravone, a pyrazalone derivative, is an antioxidant and free radical scavenger used to treat oxidative stress-related diseases. It is a proven drug to mitigate conditions prevailing to oxidative stress by inhibiting lipid peroxidation, reducing inflammation, and thereby preventing endothelial cell death. In recent years, considerable interest has been given by researchers in the derivatization of edaravone by adding varieties of substituents of versatile steric and functional properties to improve its antioxidant and pharmacological activity. This review accounts all the important methods developed for the derivatization of edaravone and the impacts of the structural modifications on the antioxidant activity of the motif.

Neoadjuvant chemotherapy for pancreatic cancer: Quality over quantity.

BACKGROUND AND OBJECTIVES: The ideal duration of neoadjuvant chemotherapy (NACT) in patients with localized pancreatic adenocarcinoma (PDAC) treated with curative intent is unclear. We sought to determine the prognostic significance of both duration of NACT and Carbohydrate Antigen 19-9 (CA19-9) normalization to NACT. METHODS: We examined patients with resectable and borderline resectable PDAC treated with NACT and chemoradiation. Patients were compared by NACT duration (2 vs. 4 months) and by CA19-9 normalization after NACT. RESULTS: Among 171 patients, 83 (49%) received 2 months of NACT, and 88 (51%) received 4 months. After NACT completion, 115 (67%) patients had persistently elevated CA19-9, and 56 (33%) had normalized. Of the 125 patients who had successful surgery, 73 (58%) had normalized CA19-9 postoperatively. Duration of NACT was not associated with overall survival (OS) while CA19-9 normalization after NACT (regardless of duration) was associated with improved OS (hazard ratio [HR] 0.56, 95% confidence interval [CI] 0.35-0.89, p = 0.02). Adjuvant chemotherapy was associated with improved OS among patients without CA19-9 normalization after NACT (HR 0.42, CI 0.20-0.86, p = 0.02) but not among those that normalized, independent of duration. CONCLUSIONS: CA19-9 normalization after NACT is a clinically significant endpoint of treatment; patients without CA19-9 normalization may benefit from additional therapy.

Interfacial Water in the SARS Spike Protein: Investigating the Interaction with Human ACE2 Receptor and In Vitro Uptake in A549 Cells.

The severity of global pandemic due to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has engaged the researchers and clinicians to find the key features triggering the viral infection to lung cells. By utilizing such crucial information, researchers and scientists try to combat the spread of the virus. Here, in this work, we performed in silico analysis of the protein-protein interactions between the receptor-binding domain (RBD) of the viral spike protein and the human angiotensin-converting enzyme 2 (hACE2) receptor to highlight the key alteration that happened from SARS-CoV to SARS-CoV-2. We analyzed and compared the molecular differences between spike proteins of the two viruses using various computational approaches such as binding affinity calculations, computational alanine, and molecular dynamics simulations. The binding affinity calculations showed that SARS-CoV-2 binds a little more firmly to the hACE2 receptor than SARS-CoV. The major finding obtained from molecular dynamics simulations was that the RBD-ACE2 interface is populated with water molecules and interacts strongly with both RBD and ACE2 interfacial residues during the simulation periods. The water-mediated hydrogen bond by the bridge water molecules is crucial for stabilizing the RBD and ACE2 domains. Near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) confirmed the presence of vapor and molecular water phases in the protein-protein interfacial domain, further validating the computationally predicted interfacial water molecules. In addition, we examined the role of interfacial water molecules in virus uptake by lung cell A549 by binding and maintaining the RBD/hACE2 complex at varying temperatures using nanourchins coated with spike proteins as pseudoviruses and fluorescence-activated cell sorting (FACS) as a quantitative approach. The structural and dynamical features presented here may serve as a guide for developing new drug molecules, vaccines, or antibodies to combat the COVID-19 pandemic.

Image Quality Evaluation in Dual-Energy CT of the Chest, Abdomen, and Pelvis in Obese Patients With Deep Learning Image Reconstruction.

OBJECTIVE: The aim of this study was to evaluate image quality in vascular and oncologic dual-energy computed tomography (CT) imaging studies performed with a deep learning (DL)-based image reconstruction algorithm in patients with body mass index of ≥30. METHODS: Vascular and multiphase oncologic staging dual-energy CT examinations were evaluated. Two image reconstruction algorithms were applied to the dual-energy CT data sets: standard of care Adaptive Statistical Iterative Reconstruction (ASiR-V) and TrueFidelity DL image reconstruction at 2 levels (medium and high). Subjective quality criteria were independently evaluated by 4 abdominal radiologists, and interreader agreement was assessed. Signal-to-noise ratio (SNR) and contrast-to-noise ratio were compared between image reconstruction methods. RESULTS: Forty-eight patients were included in this study, and the mean patient body mass index was 39.5 (SD, 7.36). TrueFidelity-High (DL-High) and TrueFidelity-Medium (DL-Med) image reconstructions showed statistically significant higher Likert scores compared with ASiR-V across all subjective image quality criteria ( P < 0.001 for DL-High vs ASiR-V; P < 0.05 for DL-Med vs ASiR-V), and SNRs for aorta and liver were significantly higher for DL-High versus ASiR-V ( P < 0.001). Contrast-to-noise ratio for aorta and SNR for aorta and liver were significantly higher for DL-Med versus ASiR-V ( P < 0.05). CONCLUSIONS: TrueFidelity DL image reconstruction provides improved image quality compared with ASiR-V in dual-energy CTs obtained in obese patients.

Total Neoadjuvant Therapy for Operable Pancreatic Cancer.

BACKGROUND: Overall survival (OS) for operable pancreatic cancer (PC) is optimized when 4-6 months of nonsurgical therapy is combined with pancreatectomy. Because surgery renders the delivery of postoperative therapy uncertain, total neoadjuvant therapy (TNT) is gaining popularity. METHODS: We performed a retrospective cohort study of patients with operable PC and compared TNT with shorter course neoadjuvant therapy (SNT). Primary outcomes of interest included completion of neoadjuvant therapy (NT) and resection of the primary tumor, receipt of 5 months of nonsurgical therapy, and median OS. RESULTS: We reviewed 541 consecutive patients from 2009 to 2019 including 226 (42%) with resectable PC and 315 (58%) with borderline resectable (BLR) PC. The median age was 66 years (IQR [59, 72]), and 260 (48%) patients were female. TNT was administered to 89 (16%) patients and SNT was administered to 452 (84%). Both groups were equally likely to complete intended NT and surgery (p = 0.90). Patients who received TNT and surgical resection were more likely to have a complete pathologic response (8% vs 4%, p < 0.01) and were more likely to receive at least 5 months of nonsurgical therapy (67% vs 45%, p < 0.01). The median OS was 26 months [IQR (15, 57)]; not reached among patients treated with TNT, and 25 months [IQR (15, 56)] among patients treated with SNT (p = 0.19). CONCLUSIONS: TNT ensures the delivery of intended systemic therapy prior to a complicated operation without decreasing the chance of successful surgery; a window of operability was not lost. Patients who can tolerate SNT will likely benefit from TNT.

CT Esophagography for Evaluation of Esophageal Perforation.

Esophageal emergencies such as rupture or postoperative leak are uncommon but may be life threatening when they occur. Delay in their diagnosis and treatment may significantly increase morbidity and mortality. Causes of esophageal injury include iatrogenic (including esophagogastroduodenoscopy and stent placement), foreign body ingestion, blunt or penetrating trauma to the chest or abdomen, and forceful retching, also called Boerhaave syndrome. Although fluoroscopic esophagography remains the imaging study of choice according the American College of Radiology appropriateness criteria, CT esophagography has been shown to be at least equal to if not superior to fluoroscopic evaluation for esophageal injury. In addition, CT esophagography allows diagnosis of extraesophageal abnormalities, both as the cause of the patient's symptoms as well as incidental findings. CT esophagography also allows rapid diagnosis since the examination can be readily performed in most clinical settings and requires no direct radiologist supervision, requiring only properly trained technologists and a CT scanner. Multiple prior studies have shown the limited utility of fluoroscopic esophagography after a negative chest CT scan and the increase in accuracy after adding oral contrast agent to CT examinations, although there is considerable variability of CT esophagography protocols among institutions. Development of a CT esophagography program, utilizing a well-defined protocol with input from staff from the radiology, gastroenterology, emergency, and general surgery departments, can facilitate more rapid diagnosis and patient care, especially in overnight and emergency settings. The purpose of this article is to familiarize radiologists with CT esophagography techniques and imaging findings of emergent esophageal conditions. Online supplemental material is available for this article. ©RSNA, 2021.

Imaging for Oncologic Response Assessment in Lymphoma.

OBJECTIVE: The purpose of this article is to examine the role of different imaging biomarkers, focusing in particular on the use of updated CT and PET response criteria for the assessment of oncologic treatment effectiveness in patients with lymphoma but also discussing other potential functional imaging methods and their limitations. CONCLUSION: Lymph nodes are commonly involved by metastatic solid tumors as well as by lymphoma. Evolving changes in cancer therapy for lymphoma and metastases have led to improved clinical outcomes. Imaging is a recognized surrogate endpoint that uses established criteria based on changes in tumor bulk to monitor the effects of treatment. With the introduction of targeted therapies and novel antiangiogenic drugs, the oncologic expectations from imaging assessment are changing to move beyond simple morphologic methods. Molecular and functional imaging methods (e.g., PET, perfusion, DWI, and dual-energy CT) are therefore being investigated as imaging biomarkers of response and prognosis. The role of these advanced imaging biomarkers extends beyond measuring tumor burden and therefore might offer insight into early predictors of therapeutic response. Despite the potential benefits of these exciting imaging biomarkers, several challenges currently exist.

Monoanionic, Bis(pyrazolyl)methylborate [(Ph3B)CH(3,5-(CH3)2Pz)2)]- as a Supporting Ligand for Copper(I)-ethylene, cis-2-Butene, and Carbonyl Complexes.

The monoanionic bidentate ligand [(Ph3B)CH(3,5-(CH3)2Pz)2)]- has been prepared from lithium bis(pyrazolyl)methanide and triphenylborane. This useful new ligand is closely related to the well-established bis(pyrazolyl)borate and bis(pyrazolyl)methane ligands but has key differences to both analogues as well. The ethylene, cis-2-butene, and carbon monoxide adducts [(Ph3B)CH(3,5-(CH3)2Pz)2]Cu(L) (where L = C2H4, cis-CH3HC═CHCH3, and CO) have been prepared from [(Ph3B)CH(3,5-(CH3)2Pz)2)]Li(THF), copper(I) triflate, and the corresponding coligand. These complexes have been characterized by NMR spectroscopy and X-ray crystallography. In all cases the bis(pyrazolyl) moiety is bound in κ2N fashion with the BPh3 group rotated to sit over the metal center, sometimes coordinating to the metal via phenyl carbons as in [(Ph3B)CH(3,5-(CH3)2Pz)2)]Li(THF) and [(Ph3B)CH(3,5-(CH3)2Pz)2]Cu(CO) or simply hovering above the metal site as in [(Ph3B)CH(3,5-(CH3)2Pz)2)]Cu(C2H4) and [(Ph3B)CH(3,5-(CH3)2Pz)2)]Cu(cis-CH3HC═CHCH3). The 13C and 1H resonances of the ethylene carbon and protons of [(Ph3B)CH(3,5-(CH3)2Pz)2)]Cu(C2H4) appear at δ 81.0 and 3.71 ppm in CD2Cl2, respectively. The characteristic CO frequency for [(Ph3B)CH(3,5-(CH3)2Pz)2]Cu(CO) has been observed at υ̅ 2092 cm-1 by infrared spectroscopy and is lower than that of free CO suggesting moderate M → CO π-back-donation. A detailed analysis of these complexes has been presented herein.

Exploration of Imaging Biomarkers for Predicting Survival of Patients With Advanced Non-Small Cell Lung Cancer Treated With Antiangiogenic Chemotherapy.

OBJECTIVE: The objective of this study was to compare imaging biomarkers, including (18)F-FDG PET, CT perfusion (CTP), and CT texture analysis (CTTA), in predicting the survival of patients with advanced non-small cell lung cancer (NSCLC) treated with antiangiogenic chemotherapy. SUBJECTS AND METHODS: A total of 35 patients (17 men and 18 women; median age, 64.0 years) with advanced NSCLC treated with antiangiogenic chemotherapy were evaluated. CTP and FDG PET were performed before the therapy, and blood flow, blood volume, mean transit time, and the maximum standardized uptake value (SUV max) of the tumor were measured. Texture parameters, including the mean value of pixels with positive values (MPP) and entropy (a measure of irregularity), were also measured on pretherapeutic unenhanced CT images, using CTTA software with a medium texture scale filtration. The best percent change in the tumor burden was also measured. These image-derived tumor parameters were then compared with progression-free survival (PFS) and overall survival (OS). RESULTS: In univariate Cox regression analysis, MPP and entropy were significantly correlated with PFS (p = 0.01 and p = 0.01, respectively), whereas SUV max, MPP, and entropy were significantly correlated with OS (p = 0.03, p = 0.04, and p = 0.0008, respectively). In Kaplan-Meier analysis, high MPP and low entropy were significantly associated with favorable PFS (p < 0.0001 and p = 0.03, respectively) and OS (p = 0.0009 and p = 0.005, respectively), and low SUV max was significantly associated with favorable OS (p = 0.01). CTP parameters and the best change in the tumor burden had no associations with survival. In multivariate analysis, only entropy was identified as an independent prognostic factor for OS (p = 0.02). CONCLUSION: CTTA is the optimal imaging biomarker for predicting the survival of patients with advanced NSCLC treated with antiangiogenic chemotherapy.

CT-guided implantation of intrahepatic fiducial markers for proton beam therapy of liver lesions: assessment of success rate and complications.

OBJECTIVE. The purpose of this study is to evaluate the safety and complications of CT-guided implantation of intrahepatic fiducial markers for proton beam therapy. MATERIALS AND METHODS. In this retrospective study, we reviewed 69 patients who underwent 149 percutaneous fiducial marker implantations for primary and metastatic hepatic tumors from April 2007 through July 2013. The implantations enabling satisfactory treatment planning and CT simulation were considered as technically successful. Major and minor procedure-related complications during and after fiducial marker implantation were documented. RESULTS. The success rate of fiducial marker implantation was 99.3% (148/149). In one patient, a fiducial marker migrated into the vascular system, which was realized during the procedure and required reimplantation. None of the patients was required to return for additional implantations. The major and minor complication rates were 0% and 2.9% (2/69), respectively. Both minor complications included small pneumothorax not requiring hospital admission. CONCLUSION. CT-guided placement of gold fiducial markers is associated with a high technical success rate with few complications, which is an essential step in the overall treatment planning and performance of proton beam therapy for the management of hepatic tumors.

Zinc-Mediated Carbene Insertion to C-Cl Bonds of Chloromethanes and Isolable Zinc(II) Isocyanide Adducts.

The zinc adduct {[HB(3,5-(CF3)2Pz)3]Zn}(+), which was generated from [HB(3,5-(CF3)2Pz)3]ZnEt and [Ph3C]{B[3,5-(CF3)2C6H3]4}, catalyzes the activation of C-halogen bonds of chloromethanes via carbene insertion. Ethyl diazoacetate serves as the carbene precursor. The presence of {[HB(3,5-(CF3)2Pz)3]Zn}(+) in the reaction mixture was confirmed by obtaining {[HB(3,5-(CF3)2Pz)3]Zn(CN(t)Bu)3}(+) using CN(t)Bu as a trapping agent. {[HB(3,5-(CF3)2Pz)3]Zn(CN(t)Bu)3}(+) loses one zinc-bound CN(t)Bu easily to produce five-coordinate {[HB(3,5-(CF3)2Pz)3]Zn(CN(t)Bu)2}(+).

Zinc(II)-Mediated Carbene Insertion into C-H Bonds in Alkanes.

The cationic zinc adduct {[HB(3,5-(CF3)2Pz)3]Zn(NCMe)2}ClO4 catalyzes the functionalization of tertiary, secondary, and primary C-H bonds of alkanes via carbene insertion. Ethyl diazoacetate serves as the :CHCO2Et carbene precursor. The counteranion, supporting ligand, and coordinating solvents affect the catalytic activity. An in situ generated {[HB(3,5-(CF3)2Pz)3]Zn}(+) species containing a bulkier {B[3,5-(CF3)2C6H3]4}(-) anion gives the best results among the zinc catalysts used.

Dose reduction for chest CT: comparison of two iterative reconstruction techniques.

BACKGROUND: Lowering radiation dose in computed tomography (CT) scan results in low quality noisy images. Iterative reconstruction techniques are used currently to lower image noise and improve the quality of images. PURPOSE: To evaluate lesion detection and diagnostic acceptability of chest CT images acquired at CTDIvol of 1.8 mGy and processed with two different iterative reconstruction techniques. MATERIAL AND METHODS: Twenty-two patients (mean age, 60 ± 14 years; men, 13; women, 9; body mass index, 27.4 ± 6.5 kg/m(2)) gave informed consent for acquisition of low dose (LD) series in addition to the standard dose (SD) chest CT on a 128 - multidetector CT (MDCT). LD images were reconstructed with SafeCT C4, L1, and L2 settings, and Safire S1, S2, and S3 settings. Three thoracic radiologists assessed LD image series (S1, S2, S3, C4, L1, and L2) for lesion detection and comparison of lesion margin, visibility of normal structures, and diagnostic confidence with SD chest CT. Inter-observer agreement (kappa) was calculated. RESULTS: Average CTDIvol was 6.4 ± 2.7 mGy and 1.8 ± 0.2 mGy for SD and LD series, respectively. No additional lesion was found in SD as compared to LD images. Visibility of ground-glass opacities and lesion margins, as well as normal structures visibility were not affected on LD. CT image visibility of major fissure and pericardium was not optimal in some cases (n = 5). Objective image noise in some low dose images processed with SafeCT and Safire was similar to SD images (P value > 0.5). CONCLUSION: Routine LD chest CT reconstructed with iterative reconstruction technique can provide similar diagnostic information in terms of lesion detection, margin, and diagnostic confidence as compared to SD, regardless of the iterative reconstruction settings.

New and evolving concepts in CT for abdominal vascular imaging.

Computed tomographic (CT) angiography has become the standard of care, supplanting invasive angiography for comprehensive initial evaluation of acute and chronic conditions affecting the vascular system in the abdomen and elsewhere. Over the past decade, the capabilities of CT have improved substantially; simultaneously, the expectations of the referring physician and vascular surgeons have also evolved. Increasingly, CT angiography is used as an imaging biomarker for treatment selection and assessment of effectiveness. However, the growing use of CT angiography has also introduced some challenges, as potential radiation-associated and contrast media-induced risks need to be addressed. These concerns can be partly confronted by modifying scanning parameters (applying a low tube voltage) with or without using software-based solutions. Most recently, multienergy technology has endowed CT with new capabilities offering improved CT angiographic image quality and novel plaque characterization while decreasing radiation and iodine dose. In this article, we discuss current and new approaches using both conventional and multienergy CT for studying vascular disease in the abdomen. We propose various approaches to overcoming commonly encountered image quality challenges in CT angiography. In addition, we describe supplemental strategies for improving patient safety that leverage the available technology.

Oncologic applications of dual-energy CT in the abdomen.

Dual-energy computed tomographic (DECT) technology offers enhanced capabilities that may benefit oncologic imaging in the abdomen. By using two different energies, dual-energy CT allows material decomposition on the basis of energy-dependent attenuation profiles of specific materials. Although image acquisition with dual-energy CT is similar to that with single-energy CT, comprehensive postprocessing is able to generate not only images that are similar to single-energy CT (SECT) images, but a variety of other images, such as virtual unenhanced (VUE), virtual monochromatic (VMC), and material-specific iodine images. An increase in the conspicuity of iodine on low-energy VMC images and material-specific iodine images may aid detection and characterization of tumors. Use of VMC images of a desired energy level (40-140 keV) improves lesion-to-background contrast and the quality of vascular imaging for preoperative planning. Material-specific iodine images enable differentiation of hypoattenuating tumors from hypo- or hyperattenuating cysts and facilitate detection of isoattenuating tumors, such as pancreatic masses and peritoneal disease, thereby defining tumor targets for imaging-guided therapy. Moreover, quantitative iodine mapping may serve as a surrogate biomarker for monitoring effects of the treatment. Dual-energy CT is an innovative imaging technique that enhances the capabilities of CT in evaluating oncology patients.

Median arcuate ligament release at the time of pancreaticoduodenectomy or total pancreatectomy.

BACKGROUND: Celiac artery compression can complicate the performance of pancreaticoduodenectomy or total pancreatectomy due to the need for ligation of the gastroduodenal artery. Median arcuate ligament release restores normal arterial flow to the liver, spleen, and stomach and may avoid complications related to poor perfusion of the foregut. METHODS: All patients who underwent median arcuate ligament release for celiac artery compression at the time of pancreatectomy between 2009 and 2023 were reviewed. Pre- and postoperative computed tomography was used to categorize celiac artery compression by the extent of compression (types A [<50%], B [50%-80%], and C [>80%]). RESULTS: Of 695 patients who underwent pancreatectomy, 22 (3%) had celiac artery compression, and a majority (17) were identified on preoperative imaging. Median celiac artery compression was 52% (interquartile range = 18); 8 (36%) patients had type A and 14 (64%) had type B compression with a median celiac artery compression of 39% (interquartile range = 18) and 59% (interquartile range = 14), respectively (P < .001). Postoperative imaging was available for 20 (90%) patients, and a reduction in the median celiac artery compression occurred in all patients: type A, 14%, and type B, 31%. Complications included 1 (5%) death after hospital discharge, 1 (5%) pancreatic fistula, 1 (5%) delayed gastric emptying, and 4 (18%) readmissions. No patient had evidence of a biliary leak or liver dysfunction. CONCLUSION: Preoperative computed tomography allows accurate identification of celiac artery compression. Ligation of the gastroduodenal artery during pancreaticoduodenectomy or total pancreatectomy in the setting of celiac artery compression requires median arcuate ligament release to restore normal arterial flow to the foregut and avoid preventable complications.

Initial experience with single-source dual-energy CT abdominal angiography and comparison with single-energy CT angiography: image quality, enhancement, diagnosis and radiation dose.

OBJECTIVES: To assess image quality of virtual monochromatic spectral (VMS) images, compared to single-energy (SE) CT, and to evaluate the feasibility of material density imaging in abdominal aortic disease. METHODS: In this retrospective study, single-source (ss) dual-energy (DE) CT of the aorto-iliac system in 35 patients (32 male, mean age 76.5 years) was compared to SE-CT. By post-processing the data from ssDECT, VMS images at different energies and material density water (WD) images were generated. The image quality parameters were rated on 5-point scales. The aorto-iliac attenuation and contrast-to-noise ratio (CNR) were recorded. Quality of WD images was compared to true unenhanced (TNE) images. Radiation dose was recorded and statistical analysis was performed. RESULTS: Image quality and noise were better at 70 keV (P < 0.01). Renal artery branch visualisation was better at 50 keV (P < 0.005). Attenuation and CNR were higher at 50 and 70 keV (P < 0.0001). The WD images had diagnostic quality but higher noise than TNE images (P < 0.0001). Radiation dose was lower using single-phase ssDECT compared to dual-phase SE-CT (P < 0.0001). CONCLUSION: 70-keV images from ssDECT provide higher contrast enhancement and improved image quality for aorto-iliac CT when compared to SE-CT at 120 kVp. WD images are an effective substitute for TNE images with a potential for dose reduction.

Determination of renal stone composition in phantom and patients using single-source dual-energy computed tomography.

PURPOSE: This study aimed to characterize the urinary tract stones in phantom and patients using single-source dual-energy computed tomography. MATERIALS AND METHODS: Twenty stones of pure crystalline composition (uric acid [UA], struvite, cystine, and calcium oxalate monohydrate) were assessed in a phantom and 11 patients (age 39-67 years) with urinary tract stones were evaluated. An initial low-dose unenhanced CT (tube potential, 120 kilovolts [peak]; milliampere range, 150-450; noise index, 26; section thickness, 5 mm) followed by a targeted dual-energy computed tomography acquisition on a single-source dual-energy computed tomography (Discovery CT 750 HDCT, GE) was performed. Uric acid and non-UA stones were defined using a 2-material decomposition (material density-iodine/water) algorithm. The stone effective atomic number (Zeff) was used to subclassify non-UA stones. The stone attenuation (Hounsfield unit) was also studied to determine its performance in predicting the composition. Ex vivo chemical analysis of the stone served as a criterion standard. RESULTS: Of the 59 verified stones (phantom, 20; patients, 39; mean size, 6 mm), there were 16 UA and 43 non-UA type. The material density images were 100% sensitive and accurate in detecting UA and non-UA stones. The Zeff accurately stratified struvite, cystine, and calcium (calcium oxalate monohydrate) stones in the phantom. In patients, Zeff identified 83% of calcium stones (n = 24), and in stones of mixed type, it resembled dominant composition. The Hounsfield unit measurements alone were 71% sensitive and 69% accurate in detecting the UA stones. CONCLUSIONS: Single-source dual-energy computed tomography can accurately predict UA and non-UA stone composition in vitro and in vivo. Substratification of non-UA stones of pure composition can be made in vitro and in vivo. In stones of mixed composition, the Zeff values reflect the dominant composition.