Advanced Faster RCNN: a non-contrast CT-based algorithm for detecting pancreatic lesions in multiple disease stages / 南方医科大学学报

OBJECTIVE@#To propose a non-contrast CT-based algorithm for automated and accurate detection of pancreatic lesions at a low cost.@*METHODS@#With Faster RCNN as the benchmark model, an advanced Faster RCNN (aFaster RCNN) model for pancreatic lesions detection based on plain CT was constructed. The model uses the residual connection network Resnet50 as the feature extraction module to extract the deep image features of pancreatic lesions. According to the morphology of pancreatic lesions, 9 anchor frame sizes were redesigned to construct the RPN module. A new Bounding Box regression loss function was proposed to constrain the training process of RPN module regression subnetwork by comprehensively considering the constraints of the lesion shape and anatomical structure. Finally, a detection frame was generated using the detector in the second stage. The data from a total of 728 cases of pancreatic diseases from 4 clinical centers in China were used for training (518 cases, 71.15%) and testing (210 cases, 28.85%) of the model. The performance of aFaster RCNN was verified through ablation experiments and comparison experiments with 3 classical target detection models SSD, YOLO and CenterNet.@*RESULTS@#The aFaster RCNN model for pancreatic lesion detection achieved recall rates of 73.64% at the image level and 92.38% at the patient level, with an average precision of 45.29% and 53.80% at the image and patient levels, respectively, which were higher than those of the 3 models for comparison.@*CONCLUSION@#The proposed method can effectively extract the imaging features of pancreatic lesions from non-contrast CT images to detect the pancreatic lesions.

The Role of Non-Contrast CT in the Diagnosis of a Rare Cause of Small Bowel Obstruction Due to Bezoar

@#Contrast Enhanced CT Abdomen is usually used to investigate the source of the small bowel obstruction. A 13-year old girl presented with signs of small bowel obstruction and was complicated with acute renal injury. Non-contrast CT Abdomen showed findings consistent with bezoar, and the findings are similar to the features seen in a contrast study. This case shows that both the plain and the contrast CT abdomen give similar findings of bezoar, one not inferior to the other.

Quality analysis of non-contrast-enhanced CT images synthesized from contrast-enhanced CT images by deep learning model / 中华放射医学与防护杂志

Objective:To synthesize non-contrast-enhanced CT images from enhanced CT images using deep learning method based on convolutional neural network, and to evaluate the similarity between synthesized non-contrast-enhanced CT images by deep learning(DL-SNCT) and plain CT images considered as gold standard subjectively and objectively, as well as to explore their potential clinical value.Methods:Thirty-four patients who underwent conventional plain scan and enhanced CT scan at the same time were enrolled. Using deep learning model, DL-SNCT images were generated from the enhanced CT images for each patient. With plain CT images as gold standard, the image quality of DL-SNCT images was evaluated subjectively. The evaluation indices included anatomical structure clarity, artifacts, noise level, image structure integrity and image deformation using a 4-point system). Paired t-test was used to compare the difference in CT values of different anatomical parts with different hemodynamics (aorta, kidney, liver parenchyma, gluteus maximus) and different liver diseases with distinct enhancement patterns (liver cancer, liver hemangioma, liver metastasis and liver cyst) between DL-SNCT images and plain CT images. Results:In subjective evaluation, the average scores of DL-SNCT images in artifact, noise, image structure integrity and image distortion were all 4 points, which were consistent with those of plain CT images ( P>0.05). However, the average score of anatomical clarity was slightly lower than that of plain CT images (3.59±0.70 vs. 4) with significant difference ( Z = -2.89, P<0.05). For different anatomical parts, the CT values of aorta and kidney in DL-SNCT images were significantly higher than those in plain CT images ( t=-12.89, -9.58, P<0.05). There was no statistical difference in the CT values of liver parenchyma and gluteus maximus between DL-SNCT images and plain CT images ( P>0.05). For liver lesions with different enhancement patterns, the CT values of liver cancer, liver hemangioma and liver metastasis in DL-SNCT images were significantly higher than those in plain CT images( t=-10.84, -3.42, -3.98, P<0.05). There was no statistical difference in the CT values of liver cysts between DL-SNCT iamges and plain CT images ( P>0.05). Conclusions:The DL-SNCT image quality as well as the CT values of some anatomical structures with simple enhancement patterns is comparable to those of plain CT images considered as gold-standard. For those anatomical structures with variable enhancement and those liver lesions with complex enhancement patterns, there is still vast space for DL-SNCT images to be improved before it can be readily used in clinical practice.

Feasibility study of spectral CT chest enhancement venous phase virtual angiography as an alternative to three phase scanning / 中华放射学杂志

Objective:To investigate the feasibility of using spectral CT chest enhancement venous phase images to obtain virtual non-contrast (VNC) images and virtual arterial phase images to achieve one phase scan instead of three phase scans.Methods:Imaging data of 100 patients who underwent spectral CT chest plain and dual-phase enhancement scans at the First Affiliated Hospital of Kunming Medical University from January to May 2022 were analyzed retrospectively. The venous phase images of all patients were post-processed to obtain virtual non contrast (VNC) and 40 keV virtual mono-energy images (VMI) for simulated arterial phase images (Vart). Image quality and lesion detection were compared between true non-contrast (TNC) and VNC images, and conventional arterial phase (CIart) and Vart images by paired t-test, Wilcoxon test and McNemar test. Objective evaluation indexes of image quality included thoracic aorta, all levels of pulmonary artery, T4 vertebral bone cancellous, chest wall fat CT value, background noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR); the subjective score of image quality was assessed by double-blind method on a 5-point scale; the assessment of lesion detection included the detection rate of calcified foci and pulmonary nodules size, density, volume, percentage of solid components and imaging characteristics. Results:Except for chest wall fat and T4 vertebral bone cancellous, the differences in CT values between VNC and TNC images were not statistically significant ( P>0.05); Except for right upper pulmonary artery and right lower pulmonary artery, the differences in background noise values and SNR between TNC images and VNC images were statistically significant ( P<0.05). Compared with CIart images, the CT values of chest wall fat were lower in Vart images ( P<0.05), and the CT values of the remaining sites were significantly higher ( P<0.05); the background noise values of all sites on Vart images were smaller than those on CIart images, and the SNR and CNR values were higher than those on CIart images ( P<0.05).The differences of subjective scores of images quality were not statistically significant between TNC and VNC images, between CIar and Vart images ( P>0.05). Taking TNC as the standard, the overall detection rate of VNC for calcification was 88.53% (301/340). Except for the short diameter of partially solid nodules, the differences of qualitative and quantitative assessment indexes of lung nodules between TNC and VNC images were not statistically significant ( P>0.05). Conclusions:Spectral CT chest venous phase 40 keV VMI can simulate arterial phase images in the diagnosis of vascular lesions, and venous phase VNC basically meets the standard of conventional plain scan, so it is feasible to replace plain scan, arterial phase and venous phase images in a certain range.

Feasibility study of reducing the radiation dose on virtual non-contrast scanning in dual-layer spectral coronary CT angiography / 中华放射医学与防护杂志

Objective:To investigate the feasibility of reducing the radiation dose on coronary artery calcium score (CS) of virtual non-contrast (VNC) scanning in dual-layer spectral coronary CT angiography(CCTA).Methods:One hundred and twenty-two patients were examined on a dual-layer spectral detector CT scanner from March 2019 to August 2020. Volume CT dose index (CTDI vol), dose length product (DLP), effective dose ( E) were all evaluated for each patient. CS was calculated from both true non-contrast (TNC) and VNC images for left anterior descending (LAD), left circumflex (LCx), right coronary artery (RCA), and the total coronary artery (Total) by two radiologists independently. Pearson′s correlation coefficient was calculated for measuring the association between variables. The correction coefficients of each branch (λ LAD, λ LCx, and λ RCA) and the average correction coefficient (λ AVG) of the total coronary artery were obtained. The calibrated calcium score (CCS_VNC) was equal to λ multiplied by CS_VNC. The CS_TNC and CCS_VNC were compared using repeated oneway analysis of variance test. Correlation analyses for CS_TNC and CCS_VNC and agreement evaluation with Bland-Altman-Plots were performed. Results:The average effective doses in TNC, CCTA and total group were 0.69, 6.47 and 7.16 mSv, respectively. The effective dose was reduced by 10.6% and the scan time was reduced by 39% while using VNC images. There were significant differences among the CS_TNC and CS_VNC of LAD, LCx, RCA and Total ( t=6.75, 5.33, 4.99, 6.60, P< 0.05). Excellent correlations were observed between CS_VNC and CS_TNC ( R2 values were 0.929, 0.896, 0.958, and 0.918; λ values were 2.18, 1.18, 2.15, and 2.07, respectively). There were no significant statistically difference among the CS_TNC, CCS_VNC AVG, and CCS_VNC LAD/RCA of the LAD and RCA (all P> 0.05). The difference was statistically significant among the CS_TNC, CCS_VNC AVG, and CCS_VNC LCx of the LCx ( F=10.94, P<0.05). The paired comparison were performed in groups and the differences were statistically significant between the CS_TNC versus CCS_VNC AVGand CCS_VNC AVG versus CCS_VNC LCx ( t=3.31, 3.43, all P<0.05). There was no significant statistically difference between the CCS_VNC LCx and CCS_VNC AVG( P>0.05). Conclusions:It was feasible to accurately evaluate the CS_VNC from spectral data in comparison to TNC imaging, and to reduce the patient radiation dose and acquisition time.

Evaluation of non-contrast magnetic resonance imaging as an imaging surveillance tool for hepatocellular carcinoma in at-risk patients

INTRODUCTION@#This study aimed to evaluate the potential of non-contrast-enhanced magnetic resonance (MR) imaging as an imaging surveillance tool for detection of hepatocellular carcinoma (HCC) in at-risk patients and to compare the performance of non-contrast MR imaging with ultrasonography (US) as a screening modality for the same.@*METHODS@#In this retrospective study, patients diagnosed with HCC between 1 January 2010 and 31 December 2015 were selected from our institution's cancer registry. Patients who underwent MR imaging and had US performed within three months of the MR imaging were included. For each MR imaging, two non-contrast MR imaging sequences - T2-weighted fat-saturated (T2-W FS) sequence and diffusion-weighted imaging (DWI) - were reviewed for the presence of suspicious lesions. A non-contrast MR image was considered positive if the lesion was seen on both sequences. The performance of non-contrast MR imaging was compared to that of hepatobiliary US for the detection of HCC.@*RESULTS@#A total of 73 patients with 108 HCCs were evaluated. Sensitivity of non-contrast MR imaging for the detection of HCC using T2-W FS and DWI was 93.2%, which was significantly higher than that of US, which was 79.5% (p = 0.02). In a subgroup of 55 patients with imaging features of liver cirrhosis, the sensitivity of non-contrast MR imaging was 90.9%, which was also significantly higher than that of US, which was 74.5% (p = 0.02).@*CONCLUSION@#Our pilot study showed that non-contrast MR imaging, using a combination of T2-W FS and DWI, is a potential alternative to US as a screening tool for surveillance of patients at risk for HCC.

Application of non-contrasted computed tomography and diffusion-weighted imaging protocols for endovascular treatment selection in patients with late-presenting or wake-up strokes / Aplicação de tomografia computadorizada sem contraste e protocolos de imagem ponderada em difusão para seleção de tratamento endovascular em pacientes com acidente vascular cerebral em fase tardia ou ao despertar

ABSTRACT Background: Among patients with acute ischemic stroke with a mismatch between deficit severity and infarct volume, thrombectomy performed within a 6-24 hours time window has efficacy and safety similar to treatment within 6 hours. However, whether magnetic resonance imaging with T2 diffusion-weighted imaging (DWI) is feasible remains to be validated. Objective: To investigate prognosis among stroke patients receiving endovascular treatment (EVT) within 6 hours and 6-24 hours using non-contrasted computed tomography (NCCT) and DWI. Methods: Overall, 209 anterior-circulation ischemic stroke patients with large-vessel occlusion who underwent EVT were divided into ≤ 6 hours and 6-24 hours groups. Patients presenting symptoms within 6 hours were treated if their NIHSS score was ≥ 7 and ASPECTS score was ≥ 5, whereas those with wake-up stroke (WUS) or presenting symptoms 6-24 hours after last seen well (WUS/late-presenting stroke, LPS) were managed if their NIHSS score was ≥ 7 and ASPECTS score was ≥ 5. Results: The percentages of patients undergoing intracranial stenting and intracranial ballooning without stenting significantly differed between two groups (p < 0.001). Grades 0, 1, 2a and 2b recanalization rates did not differ between the 6 hours and 6-24 hours groups (all p > 0.05). Grade 3 recanalization rate in the 6 hours group was significantly lower than in the 6-24 hours group (p = 0.043). The 3-month Rankin Scale score did not significantly differ between the two groups (p = 0.629). Conclusions: EVT is a safe and effective treatment for patients with WUS and LPS selected through NCCT and DWI-based simple imaging.

RESUMO Antecedentes: Entre pacientes com acidente vascular cerebral isquêmico (AVCI) agudo com divergência entre gravidade do déficit e volume do infarto, a trombectomia em 6 a 24 horas tem eficácia e segurança semelhantes ao tratamento em até 6 horas. Entretanto, a viabilidade da imagem ponderada em T2 com difusão (DWI) da ressonância magnética necessita validação. Objetivo: Investigar o prognóstico de pacientes com AVCI que recebem tratamento endovascular (EVT) em até 6 horas e de 6-24 horas usando tomografia computadorizada sem contraste (NCCT) e DWI. Métodos: Duzentos e nove pacientes com AVCI de circulação anterior submetidos a EVT foram divididos em ≤ 6 horas e 6-24 horas. Pacientes com sintomas até 6 horas foram tratados se NIHSS ≥ 7 e ASPECTS ≥ 5; aqueles com AVCI ao despertar (WUS) ou com sintomas entre 6-24 horas da última vez em que foram vistos bem (WUS/AVC de fase tardia, LPS) foram tratados se NIHSS ≥ 7 e ASPECTS ≥ 5. Resultados: As porcentagens de pacientes submetidos a implante de stent intracraniano e angioplastia intracraniana sem stent diferiram entre os dois grupos (p <0,001). As taxas de recanalização 0, 1, 2a e 2b não diferiram entre 6 horas e 6-24 horas (p> 0,05). A taxa de recanalização de grau 3 no grupo 6 horas foi menor do que 6-24 horas (p = 0,043). Pontuação na Escala Rankin (3 meses) não foi diferente (p = 0,629). Conclusões: EVT é um tratamento seguro e eficaz para pacientes com WUS e LPS selecionados por meio de imagens baseadas em NCCT e DWI.

The Diagnostic Performance of Liver MRI without Intravenous Contrast for Detecting Hepatocellular Carcinoma: A Case-Controlled Feasibility Study

OBJECTIVE: To preliminarily evaluate the diagnostic performance of an unenhanced MRI for detecting hepatocellular carcinoma (HCC) with a case-control study design. MATERIALS AND METHODS: The case group consisted of 175 patients with initially-diagnosed HCC, who underwent a 3T liver MRI. A total of 237 HCCs were identified. The number of HCCs that were smaller than 1 cm, 1 cm ≤ and < 2 cm, and ≥ 2 cm were 19, 105, and 113, respectively. For the control group, 72 patients with chronic liver disease, who did not have HCC, were enrolled. Two radiologists independently reviewed the T2 half-Fourier acquisition single-shot turbo spin echo, T2 fast spin echos with fat saturation, T1 gradient in- and out-of-phase images, and diffusion-weighted images/apparent diffusion coefficient maps to detect HCC. Per-patient analyses were performed to evaluate the sensitivity and specificity of the non-contrast MRI for diagnosing HCC. Furthermore, the per-lesion sensitivity was also calculated according to tumor size. RESULTS: In the per-patient analyses, the sensitivity and specificity of reader 1 were 86.3% (151/175) and 87.5% (63/72), respectively; while those of reader 2 were 82.9% (145/175) and 76.4% (55/72), respectively. When excluding HCCs smaller than 1 cm, the sensitivity of reader 1 and 2 were 88.0% (147/167) and 86.2% (144/167), respectively. In the per-lesion analyses, the sensitivities of reader 1 and reader 2 were 75.9% (180/237) and 70.5% (167/237), respectively. CONCLUSION: The per-patient sensitivity and specificity of non-contrast MRIs were within a reasonable range for the initial diagnosis of HCC. Non-contrast MRIs may have a potential for surveillance of HCC. Further confirmatory diagnostic test accuracy studies are needed.

The Imaging of Localization Related Symptomatic Epilepsies: The Value of Arterial Spin Labelling Based Magnetic Resonance Perfusion

Accurate identification of the epileptogenic zone is an important prerequisite in presurgical evaluation of refractory epilepsy since it affects seizure-free outcomes. Apart from structural magnetic resonance imaging (sMRI), delineation has been traditionally done with electroencephalography and nuclear imaging modalities. Arterial spin labelling (ASL) sequence is a non-contrast magnetic resonance perfusion technique capable of providing similar information. Similar to single-photon emission computed tomography, its utility in epilepsy is based on alterations in perfusion linked to seizure activity by neurovascular coupling. In this article, we discuss complementary value that ASL can provide in the evaluation and characterization of some basic substrates underlying epilepsy. We also discuss the role that ASL may play in sMRI negative epilepsy and acute scenarios such as status epilepticus.

Tomografía computarizada sin contraste para el diagnóstico de hemorragia subaracnoidea no traumática / Non-contrast computed tomography for the diagnosis of non-traumatic subarachnoid hemorrhage

INTRODUCCIÓN: La hemorragia subaracnoidea es una urgencia neuroquirúrgica que requiere un diagnóstico oportuno, debido a su gravedad y a la existencia de medidas terapéuticas que son efectivas cuando se llevan a cabo a tiempo. La secuencia diagnóstica más utilizada para descartarla es la tomografía computarizada sin contraste, que de ser negativa es seguida de una punción lumbar. Sin embargo, se ha planteado que la tomografía computarizada sin contraste negativa podría bastar por sí sola. MÉTODOS: Para responder esta pregunta utilizamos Epistemonikos, la mayor base de datos de revisiones sistemáticas en salud, la cual es mantenida mediante búsquedas en múltiples fuentes de información, incluyendo MEDLINE, EMBASE, Cochrane, entre otras. Extrajimos los datos desde las revisiones identificadas, reanalizamos los datos de los estudios primarios y preparamos una tabla de resumen de los resultados utilizando el método GRADE. RESULTADOS Y CONCLUSIONES: Identificamos tres revisiones sistemáticas que en conjunto incluyeron nueve estudios primarios. Concluimos que la exactitud diagnóstica de la tomografía computarizada sin contraste es probablemente muy alta, aunque aún existen estudios que evalúen el impacto clínico de basar las decisiones clínicas únicamente en este test.

INTRODUCTION: Subarachnoid hemorrhage is a neurosurgical emergency that requires timely diagnosis due to its severity and the existence of therapeutic measures that are effective when carried out in time. The most used diagnostic sequence to rule it out is computed tomography without contrast which, if negative, is followed by lumbar puncture. However, it has been suggested that a negative non-contrast computed tomography (without blood) may rule out the diagnosis. METHODS: To answer this question we used Epistemonikos, the largest database of systematic reviews in health, which is maintained by screening multiple information sources, including MEDLINE, EMBASE, Cochrane, among others. We extracted data from the systematic reviews, reanalyzed data of primary studies, conducted a meta-analysis and generated a summary of findings table using the GRADE approach. RESULTS AND CONCLUSIONS: We identified three systematic reviews including nine studies. We concluded the diagnostic accuracy of non-contrast computed tomography is probably very high, but the clinical impact of relying only on this test has not yet been evaluated.

Left Gastric Vein Visualization with Hepatopetal Flow Information in Healthy Subjects Using Non-Contrast-Enhanced Magnetic Resonance Angiography with Balanced Steady-State Free-Precession Sequence and Time-Spatial Labeling Inversion Pulse

OBJECTIVE: To selectively visualize the left gastric vein (LGV) with hepatopetal flow information by non-contrast-enhanced magnetic resonance angiography under a hypothesis that change in the LGV flow direction can predict the development of esophageal varices; and to optimize the acquisition protocol in healthy subjects. MATERIALS AND METHODS: Respiratory-gated three-dimensional balanced steady-state free-precession scans were conducted on 31 healthy subjects using two methods (A and B) for visualizing the LGV with hepatopetal flow. In method A, two time-spatial labeling inversion pulses (Time-SLIP) were placed on the whole abdomen and the area from the gastric fornix to the upper body, excluding the LGV area. In method B, nonselective inversion recovery pulse was used and one Time-SLIP was placed on the esophagogastric junction. The detectability and consistency of LGV were evaluated using the two methods and ultrasonography (US). RESULTS: Left gastric veins by method A, B, and US were detected in 30 (97%), 24 (77%), and 23 (74%) subjects, respectively. LGV flow by US was hepatopetal in 22 subjects and stagnant in one subject. All hepatopetal LGVs by US coincided with the visualized vessels in both methods. One subject with non-visualized LGV in method A showed stagnant LGV by US. CONCLUSION: Hepatopetal LGV could be selectively visualized by method A in healthy subjects.

Dual-energy CT virtual non-contrast technology in the diagnosis of osteoporosis: a preliminary study / 中华放射学杂志

Objective To investigate the diagnostic value of dual-energy CT virtual non-contrast (VNC) technology for osteoporosis(OP). Methods Dual-energy CT images of 50 patients with lumbar traumas were collected prospectively.Patients who suffer from vertebral bodies fractures between lumbar 1 to 4, have internal metal fixations or underwent percutaneous vertebroplasty, or presented tumors or compromised bone metabolism induced by diseases or medications were excluded.The scanning range was from the upper edge of the 12th thoracic vertebral body to the lower edge of the first sacral vertebral body. The voltages of tubes A and B were 90 kV and Sn 150 kV,and the reference tubes currents were 220 mAs and 138 mAs. Image reconstruction was performed using Advanced Modeled Iterative Reconstruction (ADMIRE)with iterative strength of 3 and convolution kernel of Qr 40.The default parameters of the virtual non-contrast software were corrected by the standard recommended by the Bone Marrow software of the post-processing platform Syngo.via,and the CT value of calcium(contrast media CM),the CT value of mixed energy images(regular CT value,rCT),the calcium density(CaD)and the fat fraction(Fat)were measured. The bone mineral density (BMD) and T score of each lumbar vertebra from lumbar 1 to lumbar 4 were measured by dual energy X-ray absorptiometry(DXA).With T score less than or equal to the 2.5 standard deviation as the gold standard for the diagnosis of OP,correlations between CT measurements and vertebral BMDs were analyzed using Pearson correlation analysis and linear regression and the diagnostic values of different CT measurements for OP were compared using receiver operating characteristic curve. Results Each of the vertebral bodies was analyzed as a single unit.Fifty of them were osteoporotic and the rest 116 were non-osteoporotic.Except for Fat,the CT measurement parameters of the osteoporotic vertebral bodies were lower than those of the ones without osteoporosis, and the difference was statistically significant (P<0.01).CM,rCT and CaD were significantly correlated with BMD(r were 0.75,0.65,0.71,all P<0.01)and there was a linear relationship(F were 209.91,120.24,167.69,all P<0.01).Meanwhile,CM,rCT,CaD and T score were also significantly correlated (r were 0.74, 0.65, 0.70, all P<0.01) with a linear relationship (F were 195.04,120.29,156.37,all P<0.01).CM,rCT and CaD had relatively high concordance rates against the OP diagnosis gold standard (respectively 81.9%, 62.2% and 81.9%). CM and CaD had higher concordance rates than rCT,the difference being statistically significant(P<0.01),and by the CM less than 239.5 HU or CaD less than 10.9 mg/cm3standard, their sensitivities of diagnosing osteoporosis were respectively 86.0% and 84.0%,while the specificities,80.2% and 81.0%.After superimposing CM and CaD, the results did not improve the diagnosis efficiency of OP (pre-superposition diagnostic performance better than post-superposition (P<0.05). Conclusion The VNC technology on DECT can do both vertebral fractures diagnosis and osteoporosis assessment at the same time, thus optimizing the clinical examination process.

The diagnostic value of dual energy virtual non-contrast images of dual-source CT in the diagnosis of com-mon benign liver diseases / 实用医学杂志

Objective To investigate the diagnostic value and limitations of dual-energy virtual non-con-trast images of dual-source CT in common benign liver diseases. Methods Dual-source CT was performed on 226 upper abdomen pathogenesis patients. The conventional non-contrast (CNC) scan was performed with single-energy mode, the arterial phase and portal phase scans were performed with dual-energy mode. The virtual non-contrast (VNC) images were derived from the portal data using liver virtual non-contrast software. 117 patients with common benign liver diseases were retrospectively analyzed in CNC and VNC. The lesion detectability, effective radiation doses for single-energy mode and dual-energy mode were compared. Results Among 117 patients, there were 28 (73.6%) hemangiomas, 58 (85.3%) calcifications or stones in VNC, but the hemangiomas, calcifications or stones in CNC were 37 (97.3%) and 68 (100%), respectively. The hemangiomas, calcifications or stones in VNC and CNC were significantly different (P 0.05). The CTDIvol, DLP and ED of dual-energy mode were obviously lower than those of single-energy mode (P < 0.05). Conclusion The detection of hemangiomas, calcifications or stones on VNC images is lower than CNC images. There is no difference in detecting cyst and hepatic steatosis. In addition, radiation dose will be reduced due to adopting VNC.VNC has potential clinical application value.

Application value of TRANCE technology in lower limb arterial occlusive disease / 医疗卫生装备

Objective To explore the application value of triggered angiography non-contrast enhanced (TRANCE) technology in diagnosing lower limb arterial occlusive disease.Methods Totally 22 lower limb arterial occlusive disease patients were randomly selected,and then underwent TRANCE and DSA examinations.The arteries from the abdomen to the lower limb were divided into abdominal aorta,common iliac artery,external iliac artery,internal iliac artery,superficial femoral artery,deep femoral artery,popliteal artery,anterior tibial artery,posterior tibial artery and peroneal artery.Totally 337 sections displayed clearly were chosen to go through examinations by TRANCE and DSA.Results Of the 337 sections there were 312 ones with the same stenoses found by TRANCE and DSA,TRANCE found 16 sections with worse stenoses and 9 milder ones than by DSA.There were 153 sections with the same moderate stenoses (≥50％) displayed by TRANCE and DSA;Of the 153 sections,there were 15 ones with worse stenoses and 6 ones with milder stenoses found by TRANCE than by DSA.Kappa value of the two methods was 0.905.Conclusion TRANCE technology is a non-invasive,safe and nonradiative diagnosing method for the lower limb arterial occlusive disease.

Choroidal Fissure Cysts in Children - Pediatrician Dilemma for Follow-up.

Background: Choroidal fissure cyst is a small cyst present in the choroidal fissure and this is a developmental variant. These are location based cysts and can either be of neuroglial or neuroepithelial, or of arachnoid in nature. These are seen as incidental finding in routine radiological cross sectional imaging studies. There is dilemma in follow up of these cysts because of their asymptomatic nature or of some vague complaints and invites a lot of debate on their follow-up. Methods: Five children of age group 10-16 years who reported to the outpatient department with vague headache, vertigo or unexplained seizures were subjected to non contrast computerized tomography (NCCT) or magnetic resonance imaging (MRI) of the head to rule out any intracranial pathology. Results: Three cases were having pure cysts in the brain while other two were found to be having various sizes and types of tuberculomas resembling with that of cystic appearances. One of the brain cyst cases was 14 years old female where NCCT head findings revealed a small cyst in the right choroid fissure location. This was subsequently confirmed as choroidal fissure cyst on multiplanar and multisectional plain MRI study. The other two cystic pathologies were vesicular stage of cysticercosis and posterior fossa arachnoid cyst. Rest of the two were tuberculomas with ring enhancement, which were confirmed on MR spectroscopy. Conclusion: The case with choroidal fissure cyst required special attention because of the concern of patient as well as clinician for the follow up. We reviewed the literature for the fate and follow up of these types of cases.

Application of non-contrast-enhanced magnetic resonance angiography in renal artery imaging / 中国医学装备

Objective: To discuss the effect of non-contrast-enhanced magnetic resonance angiography in renal artery imaging. Methods:Twenty patients were selected with suspected as the research object, using non-contrast-enhanced MR examination, simultaneously enhanced MR examination, and relatively non-enhanced imaging examination effect on the results for statistical analysis and processing. Results: Non-contrast-enhanced ratio comparing contrast-enhanced, not statistically significant (x2=1.058, P>0.05). Conclusion:Non-contrast MR angiography is an effective, safe, non-invasive, high accuracy of the evaluation of renal artery screening tool, worthy of clinical application.

Preliminary Application of Dual-energy Dual-source CT Virtual Non-contrast Imaging in Colorectal Lesions / 中国医学影像学杂志

Purpose To assess the feasibility of applying dual-energy dual-source CT virtual non-contrast (VNC) imaging in the diagnosis of colorectal diseases. Materials and Methods Eighty-ifve patients with clinically suspected colorectal lesions underwent abdominal CT scan as well as arterial and venous phase dual-energy enhanced scan, VCN images of arterial and venous phase were obtained using the dual-energy software, the differences of image quality, radiation dose and diagnostic coincidence rate between the true non-contrast scan and VNC images were compared. Results The radiation dose of two-phase dual-energy scan was 34.8%lower when compared with the conventional three-phase scans. The CT values of the intestinal lesions, metastasis lymph nodes and intestinal fat in VNC were lower than the true unenhanced scan (P0.05), and neither was the diagnostic coincidence rate for intestinal diseases (P>0.05). The noise level of images obtained from VNC was lower than that of the real non-contrast scan (P0.05). Conclusion For colorectal lesions, the virtual non-contrast images from the dual-energy dual-source CT scan can be used to reduce the radiation dose without effecting image quality and diagnosis accuracy.

The clinical utility of virtual non-contrast in the diagnosis of solitary pulmonary nodule / 实用放射学杂志

Objective To investigate the clinical utility of dual-energy virtual non-contrast CT(VNCT)of dual source CT in the di-agnosis and differential diagnosis of solitary pulmonary nodule(SPN).Methods Thirty-six patients with suspected SPN underwent chest plain single energy CT and dual-phase contrast enhanced CT (DECT)(25 and 90 s).The images of dual energy were sent to a commercial workstation for VNC image generation.CT values of SPN on VNC and true non-contrast(TNC),as well as signal-to-noise ratio(SNR)and contrast-to-noise ratio(CNR)were compared.The accuracy of calcification detection was compared according to the diameter and density of the calcification.The TNC images were used as the reference.Results CT values,SNR and CNR of VNC had no statistical difference among TNC and VNC at 25 s and 90 s(P >0.05).DECT VNC(5mm slice)could accurate detected calci-fication(diameter>2 mm,CT value>1 50 HU)in SPN.The 2 mm slice performed significantly better than 5 mm slice VNC images. Conclusion The VNC could provide consistent diagnostic information with TNC.The thin slice DECT VNC images can be used in clinical practice to replace TNC without losing small calcification in SPN,which has potential to reduce the patient radiation dose.

Virtual non-contrast of the second-generation dual-source CT:the capability to display the adipose tissue of gastric serosa / 实用放射学杂志

Objective To evaluate the capability of virtual non-contrast (VNC)of the second-generation dual-source CT (DSCT), and to display the adipose tissue of gastric serosa.Methods 48 patients with gastric cancer undergoing preoperative DSCT and sur-gery were enrolled.The true non-contrast (TNC)values and VNC values of perigastric adipose tissue were measured and compared with conventional non-contrast scanning and VNC of arterial phase and venous phase.The VNC values of perigastric adipose tissue were compared between serosal involvement group and non-serosal involvement group.Results There was statistical difference be-tween TNC values and VNC values of perigastric adipose tissue (P <0.05),the absolute differences were under 13 HU.The differ-ence of VNC values between serosal involvement group and non-serosal involvement group was significant (P <0.05).Conclusion VNC of the second-generation DSCT can clearly display the adipose tissue of gastric serosa.It has certain capability in judging sero-sal involvement.VNC has the proficiency to replace conventional non-contrast scanning.

Comparison of Non-contrast-Enhanced Computed Tomography and Intravenous Pyelogram for Detection of Patients With Urinary Calculi

PURPOSE: The aim of this study was to investigate the changing pattern in the use of intravenous pyelogram (IVP), conventional computed tomography (CT), and non-contrast-enhanced computed tomography (NECT) for evaluation of patients with acute flank pain. MATERIALS AND METHODS: We retrospectively reviewed the medical records of 2,180 patients with acute flank pain who had visited Bundang Jesaeng General Hospital between January 2008 and December 2012 and analyzed the use of IVP, conventional CT, and NECT for these patients. RESULTS: During the study period there was a significant increase in NECT use (p<0.001) and a significant decrease in IVP use (p<0.001). Conventional CT use was also increased significantly (p=0.001). During this time the proportion of patients with acute flank pain who were diagnosed with urinary calculi did not change significantly (p=0.971). CONCLUSIONS: There was a great shift in the use of imaging study from IVP to NECT between 2008 and 2012 for patients with acute flank pain.