CT For Detection Research Articles

Dual-Energy CT: Lower Limits of Iodine Detection and Quantification.

Background Assessments of the quantitative limitations among the six commercially available dual-energy (DE) CT acquisition schemes used by major CT manufacturers could aid researchers looking to use iodine quantification as an imaging biomarker. Purpose To determine the limits of detection and quantification of DE CT in phantoms by comparing rapid peak kilovoltage switching, dual-source, split-filter, and dual-layer detector systems in six different scanners. Materials and Methods Seven 50-mL iohexol solutions were used, with concentrations of 0.03-2.0 mg iodine per milliliter. The solutions and water sample were scanned five times each in two phantoms (small, 20-cm diameter; large, 30 × 40-cm diameter) with six DE CT systems and a total of 10 peak kilovoltage settings or combinations. Iodine maps were created, and the mean iodine signal in each sample was recorded. The limit of blank (LOB) was defined as the upper limit of the 95% confidence interval of the water sample. The limit of detection (LOD) was defined as the concentration with a 95% chance of having a signal above the LOB. The limit of quantification (LOQ) was defined as the lowest concentration where the coefficient of variation was less than 20%. Results The LOD range was 0.021-0.26 mg/mL in the small phantom and 0.026-0.55 mg/mL in the large phantom. The LOQ range was 0.07-0.50 mg/mL in the small phantom and 0.20-1.0 mg/mL in the large phantom. The dual-source and rapid peak kilovoltage switching systems had the lowest LODs, and the dual-layer detector systems had the highest LODs. Conclusion The iodine limit of detection using dual-energy CT systems varied with scanner and phantom size, but all systems depicted iodine in the small and large phantoms at or below 0.3 and 0.5 mg/mL, respectively, and enabled quantification at concentrations of 0.5 and 1.0 mg/mL, respectively. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Hindman in this issue.

How Low Can We Go? The Very Low Limits of Iodine Detection and Quantification in Dual-Energy CT.

How Low Can We Go? The Very Low Limits of Iodine Detection and Quantification in Dual-Energy CT.

Internal Mammary Lymph Node Visualization as a Sentinel Sonographic Sign of Tuberculous Pleurisy

Tuberculous pleurisy is one of the primary sites of extrapulmonary tuberculosis, but clinicians currently lack the diagnostic tools necessary for early recognition in the absence of typical signs and symptoms. With this study, we aimed to test the association between internal mammary adenopathies and tuberculous pleurisy (TP). 60 patients with a post-thoracoscopic histological diagnosis of granulomatosis or acute infective pleurisy were retrospectively enrolled. All of them had chest sonography and/or CT scan data available. At least two expert chest sonography physicians re-analyzed the sonography images to look for any internal mammary adenopathy. Such findings were compared to the CT data. Chest sonography showed internal mammary adenopathy ipsilateral to the pleural effusion in 97 % of 29 patients who had a diagnosis of TP, and in 13 % of those with an acute infective pleurisy (p < 0.001). Receiver operator characteristic analysis revealed 97 % sensitivity and 87 % specificity for this technique in predicting TP (area under curve 0.92 ± 0.04, p < 0.001). CT detection power and node measures were significantly similar (p < 0.001). Sonographic internal mammary node visualization ipsilateral to the pleural effusion may become a sentinel sign for TP, contributing to early diagnosis or orienting the diagnostic management towards invasive procedures in uncertain cases.

Lesion detection by [89Zr]Zr-DFO-girentuximab and [18F]FDG-PET/CT in patients with newly diagnosed metastatic renal cell carcinoma

PurposeThe main objective of this preliminary analysis of the IMaging PAtients for Cancer drug selecTion (IMPACT)-renal cell cancer (RCC) study is to evaluate the lesion detection of baseline contrast-enhanced CT, [89Zr]Zr-DFO-girentuximab-PET/CT and [18F]FDG-PET/CT in detecting ccRCC lesions in patients with a good or intermediate prognosis metastatic clear cell renal cell carcinoma (mccRCC) according to the International Metastatic Database Consortium (IMDC) risk model.MethodsBetween February 2015 and March 2018, 42 newly diagnosed mccRCC patients with good or intermediate prognosis, eligible for watchful waiting, were included. Patients underwent CT, [89Zr]Zr-DFO-girentuximab-PET/CT and [18F]FDG-PET/CT at baseline. Scans were independently reviewed and lesions of ≥10 mm and lymph nodes of ≥15 mm at CT were analyzed. For lesions with [89Zr]Zr-DFO-girentuximab or [18F]FDG-uptake visually exceeding background uptake, maximum standardized uptake values (SUVmax) were measured.ResultsA total of 449 lesions were detected by ≥1 modality (median per patient: 7; ICR 4.25–12.75) of which 42% were in lung, 22% in lymph nodes and 10% in bone. Combined [89Zr]Zr-DFO-girentuximab-PET/CT and CT detected more lesions than CT alone: 91% (95%CI: 87–94) versus 56% (95%CI: 50–62, p = 0.001), respectively, and more than CT and [18F]FDG-PET/CT combined (84% (95%CI:79–88, p < 0.005). Both PET/CTs detected more bone and soft tissue lesions compared to CT alone.ConclusionsThe addition of [89Zr]Zr-DFO-girentuximab-PET/CT and [18F]FDG-PET/CT to CT increases lesion detection compared to CT alone in newly diagnosed good and intermediate prognosis mccRCC patients eligible for watchful waiting.

Research on the Development Mechanism of Postpeak Cracks in Sandstone under Different Confining Pressures

Water inrush happens occasionally during deeper roadways excavation. It is mainly due to the lack of understanding in the formation and development mechanism of cracks and its spatial distribution pattern under ground stress. In view of this, this paper used different stress levels to represent the fracture state of different parts of the surrounding rock of the deep roadway; CT detection technique is used to scan the fractured sandstone in the postpeak state; and the CT images under different confining pressures are thus obtained. The geometrical parameters such as area, length, and width of the crack are used to describe the distribution patterns based on CT images processing technique and statistical principle. These patterns are then analyzed under varying postpeak stress levels and confining pressures. The result shows that, as the area, length, and width of the cracks get larger, number of cracks increases with decreasing stress level; at different stress levels, sandstone crack area probability density, crack length probability density, and crack width probability density form exceptional, linear, and Gaussian distribution, respectively. The amount of confining pressure affects the size of cracks and the extent of expansion. This means that the higher the confining pressure is, the easier the internal crack will be penetrated and expanded and the bigger the cracks are, and the number of cracks gets lesser. Such research results can be used to describe the propagation and evolution law of cracks under different stress states of postpeak rock, which also provide an important basis for further analysis of its permeability and the stability of roadway surrounding rock.

CT detection of primary and metastatic ileal carcinoid tumor: rates of missed findings and associated delay in clinical diagnosis.

To determine the rate of missed CT findings of ileal carcinoid tumor prior to pathologic diagnosis and the resultant diagnostic delay. Initially, 74 patients with abdominal and pelvic CT prior to pathologically-proven diagnosis of ileal carcinoid were identified. Patients were excluded when the original CT study (n = 6) or report (n = 4) was not available, resulting in a final cohort of 64 patients (mean age, 58.3years; 29M/35F); 27 (42%) patients had more than one abdominal CT prior to diagnosis. All available CT studies prior to diagnosis were retrospectively reviewed for the presence of the primary ileal tumor and metastatic disease (mesenteric and hepatic). Primary ileal tumors were prospectively missed on at least one CT scan in 64% (32/50) of patients with retrospectively identifiable disease. CT findings of mesenteric spread were missed at least once in 46% (25/54) of cases where present in retrospect. By the final pre-operative CT, hepatic metastases and bowel wall thickening were present in 55% (35/64) and 52% (33/64) of cases, respectively. In patients with missed ileal and/or mesenteric findings resulting in diagnostic delay, mean delay was 40months (range 4-98months). Initial presentation of ileal carcinoid tumor, even with mesenteric involvement, is often missed prospectively at abdominal CT, leading to delay in diagnosis until bowel or mesenteric findings become more obvious, or hepatic metastatic disease manifests. Radiologists should make a concerted effort to evaluate the bowel and mesentery in patients with long-standing vague abdominal symptoms.

Clinical time course and CT detection of metastatic disease to the small bowel.

The purpose of this study was to identify the CT characteristics of metastatic disease of the small bowel and define the clinical time course between primary tumor diagnosis and small bowel metastasis detection. A retrospective search of a pathologic database for metastases to small bowel identified 242 cases. Exclusion criteria were cases without CT (N = 49), serosal or mesenteric metastases (N = 114), or cases of direct invasion to small bowel (N = 63). The clinical records and imaging were reviewed for 16 patients. Melanoma was the most common malignancy to metastasize to small bowel (7 of 16 patients). Only one of the 16 cases was detected at the time of initial diagnosis of their primary malignancy. The average time from diagnosis of the primary malignancy or remission to the time of detection of the small bowel metastasis was 7.2 and 8.3years, respectively. The most common symptoms were gastrointestinal bleeding (N = 5) and small bowel obstruction (N = 5). In 3 cases, the masses were not identified on pre-operative CT. Metastases to the small bowel often occur many years after the initial diagnosis of the primary malignancy or entering remission and may be symptomatic. Attention to the small bowel is particularly important in melanoma patients, who may have multiple small bowel metastases, even after many years of being disease free. As oncology patients undergo numerous surveillance scans and improved therapies allow for longer survival, detection of these masses at a small size can facilitate elective resection to avert urgent surgical intervention.

Can fully iterative reconstruction technique enable routine abdominal CT at less than 1 mSv?

ObjectiveWe assessed the effect of the forward projected model-based reconstruction technique (FIRST) on lesion detection of routine abdomen CT at <1 mSv. Materials and methodsThirty-seven adult patients gave written informed consent for acquisition of low-dose CT (LDCT) immediately after their clinically-indicated, standard of care dose (SDCT), routine abdomen CT on a 640-slice MDCT (Aquillion One, Canon Medical System). The LDCT series were reconstructed with FIRST (at STD (Standard) and STR (Strong) levels), and SDCT series with filtered back projection (FBP). Two radiologists assessed lesions in LD-FBP and FIRST images followed by SDCT images. Then, SDCT and LDCT were compared for presence of artifacts in a randomized and blinded fashion. Patient demographics, size and radiation dose descriptors (CTDIvol, DLP) were recorded. Descriptive statistics and inter-observer variability were calculated for data analysis. ResultsMean CTDIvol for SDCT and LDCT were 13 ± 4.7 mGy and 2.2 ± 0.8 mGy, respectively. There were 46 true positive lesions detected on SDCT. Radiologists detected 38/46 lesions on LD-FIRST-STD compared to 26/46 lesions on LD-FIRST-STR. The eight lesions (liver and kidney cysts, pancreatic lesions, sub-cm peritoneal lymph node) missed on LD-FIRST-STD were seen in patients with BMI > 25.8 kg/m2. Diagnostic confidence for lesion assessment was optimal in LD-FIRST-STD setting in most patients regardless of their size. The inter-observer agreement (kappa-value) for overall image quality were 0.98 and 0.84 for LD-FIRST-STD and STR levels, respectively. ConclusionFIRST enabled optimal lesion detection in routine abdomen CT at less than 1 mSv radiation dose in patients with body mass less than ≤25.8 kg/m2.

55. A statistical method for assessing Low Contrast Detectability in CT: A phantom study using Filtered Back Projection and Iterative reconstructions

Purpose To calculate Low Contrast Detectability (LCD) curves using a statistical approach on CT images reconstructed with filtered back projection (FBP) and Iterative (IR) algorithms. Methods 25 axial images of a water phantom (25 cm diameter), scanned on a Somatom Definition Flash with different tube loads, were reconstructed with FBP and IR (IRIS) filters. A volume of 16 × 16 × 5 cm3 (VOI-BIG) was divided in many smaller contiguous squared ROI (ROI-lets) drawn in each axial slice and the standard deviations (SDX-m) of their mean CT values (X-m) were calculated for different dimensions. Threshold (Th) for the detectability of a low contrast object can be predicted, for an ideal observer, as Th = 3.29 ∗ SDX-m, assuming a normal distribution of X-m with a confidence level of 95% and Signal-Known-Exactly/Background Known Exactly conditions. LCD curves were obtained with this method by increasing the dimensions of the ROI-lets from 2 mm (4 pixel) to 25 mm (52 pixel) for smooth, medium-smooth and sharp FBP filters together with their corresponding iterative versions at different dose levels (CTDIvol range: 2.8–20.7 mGy). Contrast Gain (CG) was defined as the difference between 2 LCD thresholds for the same object size. Results Compared to FBP images, the noise in IR with CTDIvol = 6.9 mGy, calculated as pixel SD in the VOI-BIG, was reduced by 24%, 33% and 36% for smooth, medium-smooth and sharp filter respectively. This improvement in image quality resulted also in the LCD curves: an average CG of 0.4 HU and 2.3 HU was observed for smooth/medium and sharp filters for details dimension within 5 and 20 mm. When FBP-Smooth and IR-Medium/Smooth filters are compared, CG increase monotonically with dose reduction and object size. Conclusions Although the proposed method is valid for ideal observers only, it provides a simple but potentially attractive metric for image quality assessment and protocol optimization.

Local complexity metrics to quantify the effect of anatomical noise on detectability of lung nodules in chest CT imaging.

The purpose of this study is to (1)develop metrics to characterize the regional anatomical complexity of the lungs, and (2)relate these metrics with lung nodule detection in chest CT. A free-scrolling reader-study with virtually inserted nodules (13 radiologists × 157 total nodules = 2041 responses) is used to characterize human detection performance. Metrics of complexity based on the local density and orientation of distracting vasculature are developed for two-dimensional (2-D) and three-dimensional (3-D) considerations of the image volume. Assessed characteristics included the distribution of 2-D/3-D vessel structures of differing orientation (dubbed "2-D/3-D and dot-like/line-like distractor indices"), contiguity of inserted nodules with local vasculature, mean local gray-level surrounding each nodule, the proportion of lung voxels to total voxels in each section, and 3-D distance of each nodule from the trachea bifurcation. A generalized linear mixed-effects statistical model is used to determine the influence of each these metrics on nodule detectability. In order of decreasing effect size: 3-D line-like distractor index, 2-D line-like distractor index, 2-D dot-like distractor index, local mean gray-level, contiguity with 2-D dots, lung area, and contiguity with 3-D lines all significantly affect detectability ( ). These data demonstrate that local lung complexity degrades detection of lung nodules.

Relationship between CT signs and the expression of miR-146a in colon cancer.

Our study investigated the relationship between CT signs of colon cancer and the expression of miR-146a, to evaluate their predictive value in early diagnosis and of colon cancer. A total of 216 patients with colon cancer who were admitted to the Department of Hematology and Oncology in Yingcheng Hospital, the Second Hospital of Shandong University in Zhaoyuan City from January 2013 to March 2017 were selected as the study group. At the same time, 150 patients with benign colitis were also included to serve as the control group. CT scan was performed for patients in both the study and control groups. The expression of miR-146a in serum of patients in the study and control groups was detected by RT-qPCR, and of CT signs and miR-146a expression were analyzed. The relative expression level of miR-146a in peripheral blood of study group was significantly lower than that of the control group (t=12.180, p=0.001). Sensitivity and specificity of combined detection of CT and miR-146a in the study and control groups were 91.4 and 93.6%, respectively, which were higher than those of the single test (p<0.05). Among CT signs of study group, luminal wall, cavity and diameter changes, as well as size of tumor and surrounding tissues showed no significant correlation with the expression of miR-146a (p>0.05). The expression level of miR-146a in patients with high-risk of invasion was significantly higher than that in patients with low-risk of invasion (t=4.791, p=0.001). The expression level of miR-146a in lymph node metastasis was significantly lower than that in non-lymph node metastasis (t=3.104, p=0.002). miR-146a may be involved in the development and progression of colon cancer. Combined detection of CT and miR-146a may enhance the sensitivity and specificity of the diagnosis of colon cancer, and may provide a good predictive value for invasion and metastasis of colon cancer.

Multi-layer cube sampling for liver boundary detection in PET-CT images.

Liver metabolic information is considered as a crucial diagnostic marker for the diagnosis of fever of unknown origin, and liver recognition is the basis of automatic diagnosis of metabolic information extraction. However, the poor quality of PET and CT images is a challenge for information extraction and target recognition in PET-CT images. The existing detection method cannot meet the requirement of liver recognition in PET-CT images, which is the key problem in the big data analysis of PET-CT images. A novel texture feature descriptor called multi-layer cube sampling (MLCS) is developed for liver boundary detection in low-dose CT and PET images. The cube sampling feature is proposed for extracting more texture information, which uses a bi-centric voxel strategy. Neighbour voxels are divided into three regions by the centre voxel and the reference voxel in the histogram, and the voxel distribution information is statistically classified as texture feature. Multi-layer texture features are also used to improve the ability and adaptability of target recognition in volume data. The proposed feature is tested on the PET and CT images for liver boundary detection. For the liver in the volume data, mean detection rate (DR) and mean error rate (ER) reached 95.15 and 7.81% in low-quality PET images, and 83.10 and 21.08% in low-contrast CT images. The experimental results demonstrated that the proposed method is effective and robust for liver boundary detection.

Imaging performance and clinical value of contrast-enhanced ultrasonography and computed tomography in the diagnosis of liver cancer.

The imaging performance and clinical value of contrast-enhanced ultrasonography (CEUS) combined with CT in diagnosis of liver cancer were investigated. A total of 426 liver cancer patients treated in Yuhuangding Hospital (Yantai, China) from February 2011 to May 2016 were selected. Among them, 222 patients underwent CEUS examination, 204 patients underwent CT examination, and 102 patients underwent CEUS combined with CT examination. Sensitivity and specificity of the three methods were examined. CT showed a low density in 92.6% of patients (189 patients) and a high-low hybrid density in 6.4% (13 patients), with calcification seen in 2.5% of patients (5 patients) and bleeding in 3.4% (7 patients). Lesions: 76.5% (156 cases) of patients with multiple type, 23.5% (48 cases) with single type. CEUS showed overall enhancement in 53.2% patients (118 cases), heterogenous enhancement in 16.7% (37 cases), peripheral enhancement in 18.9% of patients (42 cases), necrosis of liquefaction in 11.3% (25 cases). In 65.3% (145 cases) of patients, the portal venous phase and the delayed phase showed a low enhancement, while 34.7% (77 cases) showed no enhancement. The sensitivity and specificity rates of CEUS combined with CT detection of liver cancer were 87.8, 88.2 and 94.1%, respectively. The ROC curve analysis showed that the sensitivity and specificity of CEUS in the diagnosis of liver cancer were 76.8 and 78.9%, respectively. The sensitivity and specificity of CT were 81.2 and 85.5%, respectively. The sensitivity and specificity of CEUS combined with CT were 90.4 and 92.7%, respectively. CEUS combined with CT detection can make-up for the deficiencies of each other and effectively improve the coincidence rate of liver cancer diagnosis, which can be used as an effective examination method for the diagnosis of liver cancer.

Correlation between model observers in uniform background and human observers in patient liver background for a low-contrast detection task in CT.

Channelized Hotelling observer (CHO) has demonstrated strong correlation with human observer (HO) in both single-slice viewing mode and multi-slice viewing mode in low-contrast detection tasks with uniform background. However, it remains unknown if the simplest single-slice CHO in uniform background can be used to predict human observer performance in more realistic tasks that involve patient anatomical background and multi-slice viewing mode. In this study, we aim to investigate the correlation between CHO in a uniform water background and human observer performance at a multi-slice viewing mode on patient liver background for a low-contrast lesion detection task. The human observer study was performed on CT images from 7 abdominal CT exams. A noise insertion tool was employed to synthesize CT scans at two additional dose levels. A validated lesion insertion tool was used to numerically insert metastatic liver lesions of various sizes and contrasts into both phantom and patient images. We selected 12 conditions out of 72 possible experimental conditions to evaluate the correlation at various radiation doses, lesion sizes, lesion contrasts and reconstruction algorithms. CHO with both single and multi-slice viewing modes were strongly correlated with HO. The corresponding Pearson's correlation coefficient was 0.982 (with 95% confidence interval (CI) [0.936, 0.995]) and 0.989 (with 95% CI of [0.960, 0.997]) in multi-slice and single-slice viewing modes, respectively. Therefore, this study demonstrated the potential to use the simplest single-slice CHO to assess image quality for more realistic clinically relevant CT detection tasks.

基于三维卷积神经网络的低剂量CT肺结节检测

基于三维卷积神经网络的低剂量CT肺结节检测

Clinical study on minimally invasive liquefaction and drainage of intracerebral hematoma in the treatment of hypertensive putamen hemorrhage.

This study aims to compare the curative effect of different treatment methods of hypertensive putamen hemorrhage, in order to determine an ideal method of treatment; and to explore the curative effect of the application of soft channel technology-minimally invasive liquefaction and drainage of intracerebral hematoma in the treatment of hypertensive putamen hemorrhage. Patients with hypertensive cerebral hemorrhage, who were treated in our hospital from January 2015 to January 2016, were included into this study. Patients were divided into three groups: minimally invasive drainage group, internal medical treatment group and craniotomy group. In the minimally invasive drainage group, puncture aspiration and drainage were performed according to different hematoma conditions detected in brain CT, the frontal approach was selected for putamen and intracerebral hemorrhage, and drainage was reserved until the hematoma disappeared in CT detection. Drug therapy was dominated in the internal medical treatment group, while surgery under general anesthesia was performed to remove the hematoma in the craniotomy group. Post-treatment neurological function defect scores in minimally invasive drainage group and internal medical group were 16.14 ± 11.27 and 31.43 ± 10.42, respectively; and the difference was remarkably significant (P< 0.01). Post-treatment neurological function defect scores in the minimally invasive drainage group and craniotomy group were 16.14 ± 11.27 and 24.20 ± 12.23, respectively; and the difference was statistically significant (P< 0.05). There was a remarkable significant difference in ADL1-2 level during followed-up in survival patients between the minimally invasive drainage group and internal medical treatment group (P< 0.01), and there was a significant difference in followed-up mortality between these two groups (P< 0.01). Clinical observation and following-up results revealed that minimally invasive drainage treatment was superior to internal medical treatment and craniotomy.

Application of novel targeting nanoparticles contrast agent combined with contrast-enhanced computed tomography during screening for early-phase gastric carcinoma.

Gastric cancer is one of the most common human tumors worldwide. The biggest bottleneck is a lack of advanced and sensitive protocols for the diagnosis of patients with early-stage gastric cancer. Therefore, more sensitive methods of diagnosing gastric cancer are urgently required to improve survival rates. In this clinical study, contrast-enhanced computed tomography (CECT) with targeting nanoparticles contrast agent (CECT-TNCA) was used to diagnose early-stage gastric cancer. The specific-targeted tyrosine kinase inhibitors of gastric cancer, including platelet-derived growth factor receptor-β, Ret and Kit, were used as TNCAs. A total of 484 patients with suspected gastric cancer were voluntarily recruited to investigate the efficacy of CECT-TNCA in the diagnosis of patients with early-stage gastric cancer. Patients with suspected gastric cancer were subjected CT and CECT-TNCA to detect whether gastric tumors existed. TNCA was orally administered before CT and CECT-TNCA (20 min). Our diagnostic data revealed that CECT-TNCA improved sensitivity and provided a new protocol to diagnose tumors in patients with suspected gastric cancer at the early stage. In addition, imaging using CECT-TNCA enabled the visualization of tiny nodules in the gastric area. CECT-TNCA diagnosed 182 patients with suspected gastric cancer as tumor-free. CECT-TNCA confirmed gastric cancer in 302 patients. Our novel diagnosis indicated significantly (P<0.01) differential signal enhancement in the gastric nodules via CECT-TNCA compared with CT, suggesting higher accuracy and the accumulation of TNCA in tumor nodules in the stomach. Furthermore, survival rates of patients detected by early-diagnosis of CECT-TNCA were significantly higher than the mean five-year survival (P<0.01). In conclusion, our investigations demonstrate that the sensibility and accuracy of CT is improved through combination with liposome-encapsulated nanoparticle contrast agent for the diagnosis of early stage gastric cancer when compared with single CT detection. CECT-TNCA improves the accuracy of CT and diagnostic confidence in assessing mural enhancement in patients with suspected gastric cancer.

Erratum to: Impact of model-based iterative reconstruction on low-contrast lesion detection and image quality in abdominal CT: a 12-reader-based comparative phantom study with filtered back projection at different tube voltages.

Erratum to: Impact of model-based iterative reconstruction on low-contrast lesion detection and image quality in abdominal CT: a 12-reader-based comparative phantom study with filtered back projection at different tube voltages.

Type 2 endoleaks in endovascular aortic repair: cone beam CT and automatic vessel detection to guide the embolization.

Background Dual-phase cone beam computed tomography (DP-CBCT) and automatic vessel detection (AVD) software are helpful tools for detecting arteries before planned endovascular interventions. Purpose To evaluate the usefulness of DP-CBCT and AVD software in guiding the trans-arterial embolization (TAE) of challenging T2 lumbar endoleaks (T2-L-EL). Material and Methods Ten patients with T2-L-EL were included in this study. The accuracy of DP-CBCT and the AVD software was defined by the ability to detect the endoleak and arterial feeding vessel, respectively. Technical success was defined as the correct positioning of the microcatheter using AVD software and the successful embolization of the endoleak. Clinical success was defined as the absence of recurrent endoleaks during follow-up and the stability of the sac diameter for persistent endoleaks. The total volume of iodinated contrast medium, overall procedure time, mean procedural radiation dose, and mean fluoroscopy time were recorded. Results The EL was detected by DP-CBCT in all patients. The AVD software identified the feeding arterial branch in all cases. In one patient, the nidus of the endoleak was not reached due to the small caliber of the feeding artery, even though the software had clearly identified the vessel route. The mean contrast volume was 109 mL, the mean overall procedural time was 74.3 min. The mean procedural radiation dose was 140.97 Gy cm2, and the mean fluoroscopy time was 29.8 min. Conclusion The use of DP-CBCT and the AVD software is feasible and may facilitate successful embolization in challenging occult T2-L-EL with complex vasculature.

Improving CT detection sensitivity for nodal metastases in oesophageal cancer with combination of smaller size and lymph node axial ratio.

To investigate the value of CT with inclusion of smaller lymph node (LN) sizes and axial ratio to improve the sensitivity in diagnosis of regional lymph node metastases in oesophageal squamous cell carcinoma (OSCC). The contrast-enhanced multidetector row spiral CT (MDCT) multiplanar reconstruction images of 204 patients with OSCC were retrospectively analysed. The long-axis and short-axis diameters of the regional LNs were measured and axial ratios were calculated (short-axis/long-axis diameters). Nodes were considered round if the axial ratio exceeded the optimal LN axial ratio, which was determined by receiver operating characteristic analysis. A positive predictive value (PPV) exceeding 50% is needed. This was achieved only with LNs larger than 9mm in short-axis diameter, but nodes of this size were rare (sensitivity 37.3%, specificity 96.4%, accuracy 85.8%). If those round nodes (axial ratio exceeding 0.66 ) between 7mm and 9mm in size were considered metastases as well, it might improve the sensitivity to 67.2% with a PPV of 63.9% (specificity 91.6%, accuracy 87.2%). Combination of a smaller size and axial ratio for LNs in MDCT as criteria improves the detection sensitivity for LN metastases in OSCC. • CT is widely used to assess metastatic lymph nodes. • CT has low sensitivity in detecting metastases using conventional criteria. • Diagnostic sensitivity of CT was improved by using lymph node axial ratio. • New diagnostic criteria provide greater diagnostic confidence with PPVs exceeding 50%. • New diagnostic criteria may help clinicians assess patients with oesophageal cancer.