Helical CT Scans Research Articles

A1762 Association of Circulating Osteoprotegerin (OPG) and RANKL with Intracranial Arterial Calcification in Hypertensive Patients

Objectives: The axis of osteoprotegerin (OPG), the receptor activator for nuclear factor kB (RANK), and RANK ligand (RANKL) is critical for skeletal biology and calcification process. However, data was scarce on its involvement in intracranial arterial calcification. Methods: Hypertensive patients with at least two cardiovascular risk factors were recruited from Shanghai Xinzhuang Community. Plasma OPG and serum RANKL were measured with ELISA. Brain tomographic angiography was performed with a GE helical CT scanner. Calcification was defined as a focal high-density lesion of at least 120 Hounsfield units at the intracranial arteries. Results: The 831 patients (mean age, 65 years; 54% women) included 465 (56%) with intracranial arterial calcification. Mean clinic blood pressure was 137/72 mmHg and 736 (89%) patients were on anti-hypertensive treatment. Plasma OPG was negatively associated with RANKL (r = − 0.25; P < 0.001). The prevalence of intracranial arterial calcification increased with plasma OPG (49.1%, 56.8% and 61.9% in tertiles 1, 2, and 3, respectively; P = 0.003) and decreased with serum RANKL (61.6%, 54.8% and 49.2%; P = 0.005). In continuous analyses, RANKL, but not OPG (P = 0.57), remained significantly associated with intracranial arterial calcification after adjustment (OR [95%CL] associated with 1-SD increase: 0.63 [0.41, 0.99], P = 0.043). Pathway analysis showed that RANKL mediated part of the association between serum lipids and intracranial arterial calcification (P = 0.008). Conclusion: Circulating RANKL was associated with intracranial arterial calcification, highlighting that it might be a marker for vascular calcification. The involving mechanisms deserve further investigation.

Evaluation of Blunt Abdominal Trauma by Helical Spiral CT Scan - A One Year Study at a Tertiary Care Hospital

Evaluation of Blunt Abdominal Trauma by Helical Spiral CT Scan - A One Year Study at a Tertiary Care Hospital

Effect of body position and time on quantitative computed tomographic measurements of lung volume and attenuation in healthy anesthetized cats.

OBJECTIVE To quantify the effect of time and recumbency on CT measurements of lung volume and attenuation in healthy cats under general anesthesia. ANIMALS 8 healthy research cats. PROCEDURES Anesthetized cats were positioned in sternal recumbency for 20 minutes and then in left, right, and left lateral recumbency (40 minutes/position). Expiratory helical CT scan of the thorax was performed at 0 and 20 minutes in sternal recumbency and at 0, 5, 10, 20, 30, and 40 minutes in each lateral recumbent position. For each lung, CT measurements of lung volume and attenuation and the extent of lung areas that were hyperaerated (-1,000 to -901 Hounsfield units [HU]), normoaerated (-900 to -501 HU), poorly aerated (-500 to -101 HU), or nonaerated (-100 to +100 HU [indicative of atelectasis]) were determined with a semiautomatic threshold-based technique. A restricted maximum likelihood analysis was performed. RESULTS In lateral recumbency, the dependent lung had significantly greater attenuation and a lower volume than the nondependent lung. Within the dependent lung, there was a significantly higher percentage of poorly aerated lung tissue, compared with that in the nondependent lung. These changes were detected immediately after positioning the cats in lateral recumbency and remained static with no further significant time-related change. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that once anesthetized healthy cats were positioned in lateral recumbency, the dependent lung lobes underwent a rapid reduction in lung volume and increase in lung attenuation that did not progress over time, predominantly attributable to an increase in poorly aerated lung tissue.

Technical Note: FreeCT_ICD: An open-source implementation of a model-based iterative reconstruction method using coordinate descent optimization for CT imaging investigations.

To facilitate investigations into the impacts of acquisition and reconstruction parameters on quantitative imaging, radiomics and CAD using CT imaging, we previously released an open-source implementation of a conventional weighted filtered backprojection reconstruction called FreeCT_wFBP. Our purpose was to extend that work by providing an open-source implementation ofa model-based iterative reconstruction method using coordinate descent optimization, called FreeCT_ICD. Model-based iterative reconstruction offers the potential for substantial radiation dose reduction, but can impose substantial computational processing and storage requirements. FreeCT_ICD is an open-source implementation of a model-based iterative reconstruction method that provides a reasonable tradeoff between these requirements. This was accomplished by adapting a previously proposed method that allows the system matrix to be stored with a reasonable memory requirement. The method amounts to describing the attenuation coefficient using rotating slices that follow the helical geometry. In the initially proposed version, the rotating slices are themselves described using blobs. We have replaced this description by a unique model that relies on trilinear interpolation together with the principles of Joseph's method. This model offers an improvement in memory requirement while still allowing highly accurate reconstruction for conventional CT geometries. The system matrix is stored column-wise and combined with an iterative coordinate descent (ICD) optimization. The result is FreeCT_ICD, which is a reconstruction program developed on the Linux platform using C++ libraries and released under the open-source GNU GPL v2.0 license. The software is capable of reconstructing raw projection data of helical CT scans. In this work, the software has been described and evaluated by reconstructing datasets exported from a clinical scanner which consisted of an ACR accreditation phantom dataset and a clinical pediatric thoracic scan. For the ACR phantom, image quality was comparable to clinical reconstructions as well as reconstructions using open-source FreeCT_wFBP software. The pediatric thoracic scan also yielded acceptable results. In addition, we did not observe any deleterious impact in image quality associated with the utilization of rotating slices. These evaluations also demonstrated reasonable tradeoffs in storage requirements and computational demands. FreeCT_ICD is an open-source implementation of a model-based iterative reconstruction method that extends the capabilities of previously released open-source reconstruction software and provides the ability to perform vendor-independent reconstructions of clinically acquired raw projection data. This implementation represents a reasonable tradeoff between storage and computational requirements and has demonstrated acceptable image quality in both simulated and clinical image datasets.

Helical CT Scan Evolution of Periprosthetic Cysts of a Stainless Steel DLC Coated Total Ankle Arthroplasty at Four Years Apart and Survival at 13 Years

Category: Ankle Introduction/Purpose: Total ankle arthroplasty (TAA) is the alternative to tibio-talar fusion in the non-conservative operative treatment of osteoarthritis. It preserves joint range of motion and prevents adjacent joints while improving quality of life and relief. Long-term studies frequently show the presence of periprosthetic cysts, which is linked to an increased risk of revision, pain or lameness. In 2012, a stainless steel, DLC coated, TAA was subjected to a clinical review and a CT scan analysis. The main objective of this study was to analyze periprosthetic cysts evolution (numbers and volumes) on helical CT scans at 4 years apart of this same cohort of patients. The secondary objective was to present clinical results and survival curve of the implant. Methods: We retrospectively reviewed the cohort of 68 cases from 2012. The average follow-up was 13 ± 6 years. 42 CT analysis of the Periprosthetic cysts, were performed at the last follow-up and compared to the 2012 analysis. Cysts were classified in 3 groups (A: 0-200mm2, B: 200-400mm2, C:&gt; 400 mm2) distributed over 7 areas. Numbers, locations and sizes were listed. The functional evaluation was performed in 2012 and at the last follow-up with the American Orthopedic Foot and Ankle Society Ankle and Hindfoot Score (AOFAS-AHS) and with the range of motion. TAR survival at 5 years were calculated for the 68 patients, and for the last 34 to avoid the learning curve effect. Two end points were defined: revision or removal of the implant for any reasons and revision or removal of the implant for aseptic loosening. TAR survival at 10 years was also analyzed thanks to the long follow-up. Results: Cysts size and prevalence were not significantly different at 4-year apart (p&gt; 0.05). No type C cysts were revealed. The mean AOFAS-AHS was 77.6 ± 15.4 [38-98] in 2012 and stable at 75 ± 18.2 [16-97] at the last follow-up. Pre-operative ankle range of motion and at the last follow-up were not significantly different. The 5-year survival for the last 34 cases were 85.2% [73.2; 97.2] for any cause of revision and 90.7% [80.7; 100] for aseptic loosening. The 10-year survival for the last 34 cases were 77.1% [67.3; 87.4] for any cause of revision and 85.4% [73.4; 98.4] for aseptic loosening. Between 2012 and 2016, one case was revised for aseptic loosening of the talar component and two cases needed fusion. Conclusion: This study shows no significant increase of cysts volume or number at 4-year apart with a stainless steel, DLC coated TAA. The clinical results and 5-year survival are similar to those in the literature. The strength of this study is its mean follow-up greater than 13 years which allowed a 10-year survival and a long-term CT scan analysis. The implant design (spherical tibial component, dual curvature PE insert, trochlear-shaped talar component), its materials (DLC coated stainless steel) and its fixation (alumina coating) ensure long-term similar clinical results, with no break after 5-year survival, and stability of cysts prevalence and size.

Abstract PD2-06: Preoperative diagnosis of sentinel lymph node metastasis using computed tomography lymphography for early breast cancer patients

Abstract Background: Sentinel lymph nodes (SLN) biopsy has been established as a standard of care in the treatment of early breast cancer. This technique represents a minimally invasive, highly accurate method of axillary staging and is an alternative to conventional axillary lymph node dissection. However, an indication of SLN navigation to metastatic disease may lead to misdiagnosis for staging. Recently, SLN identification using computed tomography lymphography (CTLG) has been reported in Japan. This study investigated the value of CTLG for preoperative prediction of SLN status in early breast cancer patients. Patients and method: Between January 2013 and August 2016, 350 breast cancer patients without clinical evidence of lymph node metastasis were treated. On the day before the operation, CTLG was performed using 64-row multidetector helical CT scanner. Patients were placed in a supine position with their arms positioned in a cranial direction with CT guidelineattached to the skin at the axilla. We performed an intradermal injection in the periareolar area, using 4 ml of iopamidolwith 1 ml of local anesthetic. The contrasted lymph route and SLN were identified in reconstructed three-dimensional imaging. The SLN spot was indicated by CT laser light navigator system. We established typical pattern of the lymphography: stain defect of SLN, stagnation of lymphatic route for preoperative diagnosis of metastatic SLN. SLN biopsy was performed using the fluorescence imaging system, Photpdynamic Eye (pde-neo, Hamamatsu Photonics Co., Japan) referring to the point by axillary compression technique by plastic device. Intraoperative pathological analysis of SLN was examined, and an axillary lymph node dissection was performed in patients with SLN metastasis pathologically. Results: The median age of the 350 patients was 59 (range 28 – 90) years old. One patient was male and others were female. CTLG were safely performed in all patients. CTLG could visualize lymphatic route and accurately identify SLN in 336 (96.0 %) and 343 (98.0 %) cases, respectively. Lymphatic routes of CTLG were completely consistent with those of fluorescence imaging. The mean number of SLN identified by CTLG was 1.1. Fifty of 350 patients had metastatic SLN pathologically, and 11 of them had micrometastases of SLNs. The accuracy for metastatic diagnosis of SLN using CTLG without micrometastasis was 84.1 %, sensitivity was 82.1 % and specificity was 84.3 %. The positive predictive value was 40.5 % and negative predictive value was 97.3 %. There were no complications associated with SLN identification. Conclusion: CTLG in SLN biopsy has some advantages in that this method is simple and quite useful for obtaining accurate anatomic images of the SLN, lymph vessels, and tumor. CTLG could select the candidate with truly node negative cases in early breast cancer patients, because it predicts lymph node metastasis preoperatively from natural status of the lymphographic image. Citation Format: Abe H, Teramoto A, Tanaka M, Yamasaki K, Yoneda K. Preoperative diagnosis of sentinel lymph node metastasis using computed tomography lymphography for early breast cancer patients [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr PD2-06.

A prospective gating method to acquire a diverse set of free-breathing CT images for model-based 4DCT

Breathing motion modeling requires observation of tissues at sufficiently distinct respiratory states for proper 4D characterization. This work proposes a method to improve sampling of the breathing cycle with limited imaging dose.We designed and tested a prospective free-breathing acquisition protocol with a simulation using datasets from five patients imaged with a model-based 4DCT technique. Each dataset contained 25 free-breathing fast helical CT scans with simultaneous breathing surrogate measurements. Tissue displacements were measured using deformable image registration. A correspondence model related tissue displacement to the surrogate. Model residual was computed by comparing predicted displacements to image registration results. To determine a stopping criteria for the prospective protocol, i.e. when the breathing cycle had been sufficiently sampled, subsets of N scans where 5 ⩽ N ⩽ 9 were used to fit reduced models for each patient. A previously published metric was employed to describe the phase coverage, or ‘spread’, of the respiratory trajectories of each subset. Minimum phase coverage necessary to achieve mean model residual within 0.5 mm of the full 25-scan model was determined and used as the stopping criteria. Using the patient breathing traces, a prospective acquisition protocol was simulated.In all patients, phase coverage greater than the threshold necessary for model accuracy within 0.5 mm of the 25 scan model was achieved in six or fewer scans. The prospectively selected respiratory trajectories ranked in the (97.5 ± 4.2)th percentile among subsets of the originally sampled scans on average. Simulation results suggest that the proposed prospective method provides an effective means to sample the breathing cycle with limited free-breathing scans. One application of the method is to reduce the imaging dose of a previously published model-based 4DCT protocol to 25% of its original value while achieving mean model residual within 0.5 mm.

Low dose computed tomography KUB region for management of urolithiasis in Indian scenario

Background: The incidence, prevalence and recurrence of urolithiasis are very high; especially in the north-western part of India. Ultrasonography has decreased sensitivity and specificity as compared with NCCT for detection of both renal and ureteral calculi. Drawbacks of NCCT in terms of radiation exposure, cost and repeatability can be overcome by Low dose NCCT protocols. Low dose NCCT can be an investigation with high diagnostic accuracy, less radiation hazards and financial acceptability. Aim of this study was to evaluate use of Low dose CT-KUB over ultrasound (US) for diagnosis of urolithiasis, in Indian scenario.Methods: This is a prospective study, at Tertiary Care Hospital. Patients with acute flank pain, who underwent both US and Low dose NCCT within an interval of 24 hours, at Tertiary Care Hospital. Helical CT scanner (Phillips 128 slice medical systems) with exposure factors setting of KVp 120 and mAs 70 was used.Results: A total of 136 Patients with mean age of 33.01 years (range 19-62 years, SD 10.93), were examined with 82(60.29%) males and 54(39.7%) females, average BMI was 25.07(range 17.2 to 35.02). Low Dose NCCT has a sensitivity of 95% (CI of 89.43-98.14%) and specificity of 87.50% (95% CI of 61.65-98.45%) in the diagnosis of urolithiasis. Mean effective dose of radiation administered in low dose CT-KUB was 1.8-2.2 mSv.Conclusions: In view of information, reliability, repeatability, radiation exposure and cost acceptability; unenhanced Low dose CT-KUB region should be the preferred investigation for the management of urolithiasis, in the scenario of a developing country.

Digital Assessment of the Implantation Angle of Proximal Femoral Nail Antirotation Helical Blade Using CT Three-dimensional Reconstruction

ABSTRACTObjectives: To facilitate simple and safe manipulation during proximal femoral nail antirotation (PFNA) operation, we studied the range of safe implantation angle of the helical blade of the PFNA system by using a digital-based three-dimensional reconstruction model of CT images. Methods: Thirty-five healthy volunteers were recruited. Original multilayer helical CT scan data of the left femur were collected and imported into Mimics software. Anatomic features of the femur, including the safe implantation angle, anterior and posterior angle, were measured. Differences in each angle between male and female subjects were compared using Student's t test, and the determinants of each angle were analyzed by linear regression. Results: The mean safe implantation angle was 30.09° ± 4.73°, the mean anterior angle was 15.82° ± 2.07°, and the mean posterior angle was 14.27° ± 3.19°. All the three angles were greater in males than females (P < 0.05). Neck shaft angle and the diameter of the femoral neck and head were linearly correlated with the safe implantation angle, the anterior and posterior angle, respectively. Femoral neck diameter was a significant determinant of the safe implantation angle and posterior angle, respectively. Moreover, femoral neck diameter and femoral head diameter were significant determinants of the anterior angle. Conclusions: The study has introduced and delineated a novel parameter, the safe implantation angle, for FPNA surgery, which may help orthopedic surgeons in deciding a safe range of PFNA operation and improve the accuracy of PFNA helical blade implantation.

Evaluation of high dose volumetric CT to reduce inter-observer delineation variability and PTV margins for prostate cancer radiotherapy

PurposeThe aim was to determine whether the enhanced soft tissue contrast provided by high-dose volumetric CT (HDVCT) can reduce inter-observer variability in delineating prostate compared to helical conventional CT (CCT) scans and 3T MRI scans for patients undergoing radical prostate cancer radiotherapy. Secondly, to quantify the potential PTV reduction with decreased inter-observer variability. Materials and methodsA 320 slice volumetric CT scanner was used. The wide-detector coverage of 16cm enabled volumetric image acquisition of prostate gland in one rotation. Three imaging studies were performed on ten patients. CCT and HDVCT were performed consecutively at the same coordinate system followed by MRI. Five radiation oncologists delineated the prostate. ResultsThe inter-observer variability is 2.0±0.6, 1.9±0.4 and 1.8±0.4mm for CCT, HDVCT and MR respectively with the maximum at the apex region. Comparing inter-observer difference variability between CCT and HDVCT with MR indicates that observers have larger variations in contouring using CCT than HDVCT especially at apex. Jaccard index of HDVCT is significantly higher than CCT with a mean difference of 0.03 (p=0.011). Both MRI and HDVCT provide the opportunity for a 2mm PTV margin reduction at the apex compared to CCT. ConclusionInter-observer variability in delineation remains an important source of systematic error. HDCTV for treatment planning reduces this error without recourse to MRI and permits a PTV reduction of 2mm at the apex. The margins required to account for residual error with any imaging modality are still greater than are used in typical current practice.

Calculus in a Paraureteral Diverticulum Masquerading as Calculus at the Ureterovesical Junction on Unenhanced Helical CT Scan

Unenhanced Helical CT scan done in a prone position differentiates a calculus at the ureterovesical junction from the a calculus in abladder lying near the ureteric orifice by the fact that the calculus at the ureterovesical junction doesnot change its position owever a calculus in a paraureteral diverticulum mimicas a calculus at the ureterovesical junction and maynot show change in position in prone scan if the diverticulum has a narrow mouth We present a case to highlight this point

Preferred treatment position between supine and prone for pelvic radiation therapy; quantification of the intrafractional body motion component by 3D surface imaging system

Purpose: We investigated the preferred treatment position between supine and prone during pelvic radiation treatment using real time tracking data from AlignRT. Our findings will provide valuable information regarding the role of intrafractional body motion in answering the question of prone versus supine position for pelvis radiation. Methods: Ten patients receiving pelvic radiation were enrolled in this study. For each patient, two simulation helical CT scans were performed, one in supine and one in prone position. Body surface contours were automatically generated and then exported to the AlignRT system as reference images. AlignRT continuous patient body motion tracking (1.5 to 2 minutes) was performed for both positions for each patient once per week for five weeks. The equivalent patient body motion along three principle directions was calculated from the six degree of freedom real time patient displacements data. The maximum and the standard deviation (STD) of equivalent patient body motion were calculated, so as the average of maximum and STD of equivalent patient motion over five fractions. These were then compared between supine and prone orientations. Results: A correlation was observed between the intrafractional body motion and large BMI. For overweight/obese patients, the intrafractional body motion was smaller for the supine position in both vertical and longitudinal directions. For normal range BMI patients, we observed no clear advantage for either supine or prone position in both vertical and longitudinal directions. In lateral direction, the intrafractional motion did not have statistically difference between two positions. Conclusion: Our study shows that the amount of intrafractional body motion between supine and prone orientation is correlated with patient BMI. Overweight/obese patients experienced significantly less overall body motion in supine orientation. The preferred treatment position for normal BMI patients was seen to be individually variable.

Estimation of Local Data-Insufficiency in Motion-Corrected Helical CT

Previously we have proposed a reconstruction algorithm which corrects for known rigid motion in helical CT. This paper describes a method to determine data-insufficiency of helical CT data affected by rigid object motion. We propose a local measure that quantifies the degree to which Tuy’s completeness condition is violated in each voxel. This measure identifies regions for which artifact-free reconstruction is not assured. For every voxel, a local data-insufficiency measure is computed. We call the resulting image the Tuy map. Its values range from 0 to 1, where high values indicate data-insufficiency. As shown by classic theory, exact reconstruction is not possible, where the Tuy map contains high values. The predictions based on this Tuy map were verified with simulated helical-CT data, where the object moved during the scan and the motion was correctly taken into account during reconstruction. We also analyzed the reconstruction from an actual motion-corrected CT-scan of a moving phantom. For motion-free helical scans, the Tuy map was close to zero everywhere and the reconstructions were artifact-free. Rigid motion induces an effective source trajectory (with respect to a stationary patient) which, combined with axial or even transaxial truncation, can cause incomplete sampling. In simulations with severe motion or transaxial detector truncation, the Tuy map contained high values and the reconstructions suffered from artifacts. In the phantom scan, the combination of a high pitch and severe motion created artifacts which the Tuy map successfully indicated. In all cases, the Tuy map indicated all regions with incomplete sampling which were prone to reconstruction artifacts. However, we also contrived a special case, where exact reconstruction was not assured although the local Tuy condition was satisfied. The proposed method provides a useful measure of data-incompleteness, which can be used to verify the validity of motion-corrected helical CT scans. The method is general and could also be useful for other tomographic problems for which no exact data sufficiency measures are available.

Effect of total lung capacity, gender and height on CT airway measurements.

Testing the hypothesis that CT airway measurements could be influenced by total lung capacity (TLC), gender and height in normal individuals. In this ethics committee-approved prospective trial, 87 healthy never-smoking volunteers who provided written informed consent were included. From a helical CT scan of the chest, the wall thickness (WT) and the lumen area were twice measured in the third- and fourth-generation airways by three readers using a dedicated software. In addition, the TLC was also measured using CT (TLCCT). The percentage of airway area occupied by the wall (WA%) and the square root of wall area at an internal perimeter of 10 mm (√WAPi10) were calculated. CT airway measurements were compared between genders by using a mixed linear model. The correlations between height, TLCCT and CT airway measurements were tested by using a Pearson correlation analysis. These correlations were arbitrarily considered as significant if there was a significant correlation observed for each of the six measurement sessions. √WAPi10, WT3rd and WT4th were significantly different between genders. For both genders, there was no significant correlation between any airway measurements and TLCCT. In females only, WT3rd and WT4th were significantly and negatively correlated with height. √WAPi10, WT3rd and WT4th are different in males and females. WT3rd and WT4th are correlated with height in females only but not with TLC or in males. Advances in knowledge: CT airway measurements are influenced by gender and by height in females only but not by TLC. They should be adjusted according to gender and height in females.

Technical Note: Analysis of motion blurring artifact in fast helical free-breathing thoracic CT scans.

The aim of this study was to measure and characterize breathing-induced motion artifacts in fast helical free-breathing CT scans. Ten lung cancer patients were scanned using fast helical CT during free breathing. In each case, 25 low-dose CT scans were acquired in alternating craniocaudal and caudocranial directions. A bellow-based breathing surrogate was simultaneously acquired. A published breathing motion model was used to estimate the diaphragm craniodaudal velocity at each CT scan. The Hounsfield unit (HU) profiles passing through a small square (7 × 7 mm2 ) portion of the diaphragm were examined and fit to error functions, which were used to characterize the motion blur. The HU profiles that intersected diaphragm-adjacent non-parenchymal tissue were excluded from analysis. The five profiles for each scan that were best isolated from non-parenchymal tissue were used to determine the amount of blurring. A convolution-based blurring model was also employed to compare against the human data. There was a distinct relationship between blurring and diaphragm speed. The convolution model well described the blurring behavior in the patients. Most of the CT scans were acquired at tissue velocities less than 20 mm s-1 , which was the threshold where blurring exceeded 1 mm (corresponding to the slice spacing in this study). Breathing motion-induced blurring occurs even for relatively fast modern helical CT scans. Measurable motion-induced blurring occurs for velocities greater than 15 mm s-1 and greater than 1 mm for velocities greater than 20 mm s-1 . Methods to manage the residual blurring artifacts will need to be developed to maximize the image quality for free-breathing CT protocols.

228P Significance of para-aortic lymph node dissection for advanced gastric cancer patients following DCS therapy

Background Although JCOG0405 revealed preoperative S-1 plus cisplatin chemotherapy followed by surgery was safety and effective, it was not clear for detailed consideration, such as the correlation between the number of metastatic lymph nodes and prognosis. In this study, we demonstrated the significance of para-aortic lymph node dissection (PAND) for advancedgastric cancer patients following DCS therapy. Methods Between July 2005 and November 2015, we evaluated retrospectively 24 advanced gastric cancer patients with para-aortic lymph node metastasis diagnosed by thin slice helical CT scan, without hematological metastasis or disseminated metastasis (16a2b1: 14, +a: 10). Patients received two or three cycles of preoperative chemotherapy consistingofdocetaxelandcisplatin(35mg/m2) onday1 and15andoralS-1 (40mg/m2 twice daily) on day 1-14 every 4weeks. After chemotherapy, gastrectomywith systematic PAND (16a2b1) was performed. The lymph nodes with disappeared cancer cellsduetochemotherapyweredeterminedasfollows:noevidenceofcancercellsbyH- E staining; lymphoid follicles were disturbed by fibrosis and granulomatous changes. Results Response rate was 92%, and pathological response rate was 77%. The adverse eventsrelatedDCStherapy(G3/4) were38%ofneutropenia,8%ofdiarrheaand8%of anorexia. Gastrectomywith PANDrequired396min(median) ofoperation timeand lost1225gofblood.Mediannumberofdissectedpara-aorticlymphnodewas13. Surgery related complications were anastomotic leakage in 2, chyle leakage in 2, and pancreas fistula in 1, postoperative bleeding in 1 and SSI in 1. The mean number of residual cancer cells in dissected para-aortic lymph node was 6, in which small lymph nodes without diagnosis as metastasis were contained. Three-years overall survival was 53%.Thepatientswith3morethanPANmetastasisorwithexpandlymphnode metastasis beyond 16a2b1 showed significantly worse prognosis than patients without them. Conclusions:AlthoughPANDfollowingDCStherapyhasunderwentsafely,this therapy should be only performed in specialized institutions. To improve prognosis, systematic PAND or basin dissection should be recommended rather than pick up dissection. Clinical trial indentification UMIN000006036 Legal entity responsible for the study N/A Funding N/A Disclosure All authors have declared no conflicts ofinterest.

CT and MRI features of aggressive angiomyxoma

Objective To analyze the imaging features of aggressive angiomyxoma (AAM) on CT and MRI. Methods Seven patients with pathologically confirmed AAM had CT and/or MRI examination within 1 week prior to surgery. Six patients had multi-slice helical CT scanning while four of the six patients had multi-phase contrast enhancement. Five patients had MR scanning with contrast administration covering the chest, mid-abdomen or pelvis. The imaging and pathological findings were retrospectively reviewed. Results (1) CT presentations: pre-contrast CT images revealed isodensity (1 case), heterogeneous density (5 cases), cystic degeneration (2 cases) and mural nodule (2 cases). Contrast CT images showed homogeneous and gradual enhancement (1 case), heterogeneous and progressive enhancement (3 cases), whorl sign (3 cases) and opacification of small vessels (3 cases). (2) On MR images, five cases showed high or slightly high signal on T2WI; three cases presented with whorl sign; two cases had cystic degenerations. Iso-signal or low-signal was shown at T1WI in all five cases. DWI demonstrated high or mildly high signal in five cases. At contrast images, a whole-lesion homogeneous and gradual enhancement was present in one case. Four cases revealed progressive and expanding enhancement, where whorl sign and gradual enhancement were present in three cases. A progressive ascending pattern of time-signal curve was delineated in three cases. (3) Microscopically, the tumor comprises of poorly-defined satellite or spindle cells with sparse cytoplasm and varied sizes of vessels, which distribute among stroma with rich collagen fibre and myxoid. Those components were heterogeneous to congregate compact cell cluster. The stroma in four cases was abundant in collagen fibre that was aligned with myxoid stroma and tumor cell alternately. Conclusion AAM exhibits characteristic CT and MRI features. The imaging features correlated well with pathological findings. Key words: Myxoma; Tomography,X-ray computed; Magnetic resonance imaging; Pathology

Optimizing radiation exposure for CT localizer radiographs

IntroductionThe trend towards submillisievert CT scans leads to a higher dose fraction of localizer radiographs in CT examinations. The already existing technical capabilities make dose optimization of localizer radiographs worthwhile. Modern CT scanners apply automatic exposure control (AEC) based on attenuation data in such a localizer. Therefore not only this aspect but also the detectability of anatomical landmarks in the localizer for the desired CT scan range adjustment needs to be considered. Materials and methodsThe effective dose of a head, chest, and abdomen-pelvis localizer radiograph with standard factory settings and user-optimized settings was determined using Monte Carlo simulations. CT examinations of an anthropomorphic phantom were performed using multiple sets of acquisition parameters for the localizer radiograph and the AEC for the subsequent helical CT scan. Anatomical landmarks were defined to assess the image quality of the localizer. CTDIvol and effective mAs per slice of the helical CT scan were recorded to examine the impact of localizer settings on a helical CT scan. ResultsThe dose of the localizer radiograph could be decreased by more than 90% while the image quality remained sufficient when selecting the lowest available settings (80kVp, 20mA, pa tube position). The tube position during localizer acquisition had a greater impact on the AEC than the reduction of tube voltage and tube current. Except for the use of a pa tube position, all changes of acquisition parameters for the localizer resulted in a decreased total radiation exposure. ConclusionA dose reduction of CT localizer radiograph is necessary and possible. In the examined CT system there was no negative impact on the modulated helical CT scan when the lowest tube voltage and tube current were used for the localizer.

Computed tomographic findings of pulmonary atelectasis in healthy anesthetized Beagles.

OBJECTIVE To characterize the extent and location of atelectasis in healthy anesthetized dogs positioned in lateral recumbency and to determine whether repositioning dogs in sternal recumbency would resolve atelectasis. ANIMALS 6 healthy adult Beagles. PROCEDURES Each dog was anesthetized and underwent a CT examination twice with a 2-week interval between examinations. Once anesthetized, each dog was positioned in sternal recumbency, and a breath-hold helical transverse thoracic CT scan was acquired. The dog was then positioned in lateral recumbency for 30 minutes, and images were obtained at 5 preselected sites at 3, 8, 13, 20, and 30 minutes after repositioning (phase 1). Then, the dog was repositioned in sternal recumbency, and CT images were obtained at the 5 preselected sites at 5, 10, and 20 minutes after repositioning (phase 2). The protocol for the second examination was the same as the first except the dog was positioned in the opposite lateral recumbency during phase 1. The attenuation and cross-sectional area of the lung lobes at the preselected sites were measured and compared over time. RESULTS Lateral recumbency did not cause atelectasis in any of the dogs. Patchy areas of abnormally increased attenuation were infrequently detected in the left cranial lung lobe when dogs were positioned in left lateral recumbency, and those areas failed to resolve when dogs were positioned in sternal recumbency. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that the extent of lung attenuation changes was minimal in healthy anesthetized Beagles positioned in lateral recumbency and should not preclude CT examination.

Volumetric study of sphenoid sinuses: anatomical analysis in helical computed tomography.

The sphenoid sinus is the most inaccessible part of the face, being inside the sphenoid bone and closely related to numerous vital neural and vascular structures. The objective of this study was to analyze and evaluate the variation of anatomy and the volume of the sphenoid sinus using helical computed tomography and medical imaging software. A total of 47 helical CT scans of sinuses of male and female individuals aged 18-86years were selected. The images were formatted using ITK-SNAP software, consisting of three steps: (1) segmentation; (2) volumetric analysis and (3) 3D reconstruction. The sphenoid sinuses were also classified according to Hammer, i.e., in conchal, pre-sellar, sellar and post-sellar types. A single investigator, who is specialist in dental radiology and was trained and calibrated, performed the volume and image analysis. After 15days, the segmentations were repeated. The Dunn's multiple comparison test revealed significant differences in the volume rankings between the right and left sides (P=0.0002), with the post-sellar type presenting the greatest volume on the right side compared to pre-sellar and sellar types. In the left sphenoid sinuses, the post-sellar type showed the greatest volume. The Lin's correlation coefficient showed excellent reproducibility values. According to the applied methodology, it was found that the volume of the sphenoid sinus was influenced by neither age nor gender (P>0.005). There was difference in the volumes of sphenoid sinus on the right and left sides and in the anatomical classification.