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AIM: To evaluate a novel deep-learning denoising method for ultra-low dose CT (ULDCT) in the assessment of coronary artery calcium score (CACS). MATERIALS AND METHODS: Sixty adult patients who underwent two unenhanced chest CT examinations, a normal dose CT (NDCT) and an ULDCT, were enrolled prospectively between September 2017 to December 201. A special training set was created to learn the characteristics of the real noise affecting the ULDCT implementing a fully convolutional neural network with batch normalisation. Subsequently, the 60 ULDCTs of the evaluation set were denoised. Two blinded radiologists assessed the NDCT, ULDCT, and denoised-ULDCT (DULDCT), assigning a CACS and categorised each scan as having a score above or below 100 and presence of calcifications (score 0 versus >0). Statistical analysis was used to evaluate the agreement between the readers and differences in CACSs between each imaging method. RESULTS: After excluding one patient, the cohort included 59 patients (median age 67 years, 58% men). The ULDCT median effective radiation dose (ERD) was 0.172 mSv, which was 2.8% of the NDCT median ERD. Denoising improved the signal-to-noise ratio by 27.7% (p<0.001). Interobserver agreement was almost perfect between readers (intraclass correlation coefficient >0.993). CACSs were lower for ULDCT and DULDCT as compared to the NDCT (p ≤ 0.001). In differentiating between the presence and absence of coronary artery calcifications, DULDCT showed greater accuracy (98-100%) and positive likelihood ratio (14.29->99) compared to ULDCT (92% and 2.78, respectively). CONCLUSION: DULCT significantly reduced the image noise and better identified patients with no coronary artery calcifications than native ULDCT.

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AIM: To present the computed tomography (CT) imaging features of floating aortic thrombus with emphasis on clinical and radiographic predictors for systemic shower emboli. MATERIALS AND METHODS: A retrospective computerised search for patients with protruding thoracic aortic thrombus on CT was conducted. Clinical and demographic characteristics were retrieved from medical files. Patients were divided into two groups: symptomatic and asymptomatic, based on the presence or absence of documented systemic emboli at the time of diagnosis or during follow-up. CT imaging features were analysed: location and extent of systemic emboli, presence or absence of thrombus insertion calcification, percentage of thrombus circumference that is attached to the aortic wall and thrombus volume. Clinical and demographic variables and CT imaging features were analysed as potentially associated with symptomatic emboli. RESULTS: The symptomatic group included 6/15 (40%) patients and the asymptomatic group included 9/15 (60%) patients. Patients in the symptomatic group were significantly younger (symptomatic: 53.3±11.7 years, asymptomatic: 76.9±8.4 years, p=0.003). All the symptomatic patients were women (100%), while 2/9 (22.2%) of the asymptomatic patients were women, (p=0.007). A non-calcified insertion site was more frequent in the symptomatic group (symptomatic 4/6 [66.7%] versus asymptomatic group 1/9 [11.1%], p=0.011). The percentage of thrombus circumference attached to the aortic wall was significantly smaller in symptomatic patients (symptomatic: 31.8±8.4%, asymptomatic: 43.7±5%, p=0.003). CONCLUSION: The imaging features of symptomatic floating thrombus include a narrow base of attachment and lack of insertion calcification. Free-floating thrombus should be actively sought and diagnosed or excluded when performing CT andiography for emboli.

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AIM: To assess the frequency of undetected colon cancer on conventional abdominal CT and to evaluate the imaging features that are characteristic of those cancers. MATERIALS AND METHODS: The present study included consecutive patients diagnosed with colorectal cancer at colonoscopy (2006-2015) who also underwent abdominal computed tomography (CT) performed for various reasons within a year prior to the colonoscopy. The frequency of undetected lesions was evaluated for the original CT interpretations ("original readers"). Two radiologists ("study readers"), blinded to the tumour location, independently performed interpretations oriented for colon cancer detection. The study readers analysed the imaging features of detected tumours (tumour shape, length, maximal wall thickness, free fluid, fat stranding, vascular engorgement, stenosis, and lymphadenopathy). Imaging features of the cancers undetected by the original readers were evaluated. RESULTS: The study included 127 patients. The original readers' frequency of undetected cancer was 25/127 (19.7%). Each study reader could not identify the cancer in 8/127 (6.3%) patients. Imaging features associated with undetected cancers by the original readers included the absence of fat stranding (p=0.007, p=0.003), absence of vascular engorgement (p<0.0001, p<0.0001) and absence of lymphadenopathy (p=0.005, p=0.004). Undetected tumours were shorter than those detected (original reader: 33.2±11.9 versus 51.4±18.2 mm; study reader: 32.5±9.6 versus 61.3±23.4 mm; p<0.001). CONCLUSION: Colon cancer is undetected in 20% of abdominal CT examinations in patients subsequently proven to have colon cancer at colonoscopy. The absence of fat stranding, vascular engorgement, or lymphadenopathy, and an average tumour length of 3.3 cm are contributing factors for failure of detection. Radiologists' training should emphasis these findings as it may improve cancer detection, and clinicians should be aware of the limitations of abdominal CT.

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PURPOSE: 1) To evaluate and classify the indications for fetal brain MRI in a tertiary referral center. 2) To assess the contribution of fetal brain MRI to fetal neurosonography. MATERIALS AND METHODS: A retrospective study in a tertiary medical center during a two-year period (2011 - 2012) included pregnant women who underwent fetal brain MRI. MRI was implemented at 32 weeks of gestation unless a severe abnormality possibly requiring earlier medical intervention was suspected. RESULTS: 633 patients were included, 40 (6.3%) underwent repeated examinations with a total of 733 fetal MRI scans. Patients were classified to three main indication cohorts: Suspected primary brain anomaly (52.9%), non-CNS disorders (32.5%) and obstetrical complications (14.6%). These cohorts were further divided into 16 separate groups with lateral ventricle abnormalities being the most common (23.7%), followed by exposure to TORCH (17.5%) and cerebral cortex abnormalities (13%). 149 (19.3%) fetal MRI scans demonstrated additional findings. Repeated examinations were commonly implemented in complicated monochorionic-biamniotic (MCBA) twin pregnancies (34.6%) and in cases of supra-tentorial cysts (19%). The average gestational age for MRI scan in the MCBA group was 26 ±â€Š5 weeks in comparison to ≥ 31st weeks in all other groups (p < 0.001). CONCLUSION: The current study describes a detailed picture of fetal brain MRI indications. Most patients were referred because of CNS anomalies. The impressive diversity of 16 separate entities emphasizes the expanding use of fetal brain MRI. Complicated MCBA pregnancies, which may have dramatic events, constitute a unique challenge due to early and repetitive MRI examinations and may serve as a role model for the contribution of fetal MRI during antenatal evaluation. The contribution of MRI to prenatal evaluation in various indications is discussed.

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AIM: To evaluate a revised protocol for whole-body computed tomography (CT) for multi-trauma patients in an emergency department and compare it to conventional protocols. MATERIALS AND METHODS: Forty-two of 82 multi-trauma patients underwent unenhanced CT examinations of the head, cervical spine, and upper abdomen, followed by an arterial-phase contrast-enhanced CT examination of the thorax and a porto-venous scan of the abdomen and pelvis (conventional protocol). The other 40 patients underwent unenhanced CT examinations of the head, cervical spine, and upper abdomen, followed by a one-step acquisition of the thorax, abdomen, and pelvis using a 64-section multidetector CT (MDCT) system following a triphasic injection (revised protocol). Contrast enhancement was measured in the ascending, descending, and abdominal aorta, common iliac arteries, inferior vena cava (IVC), liver, spleen, and kidneys. Image count, radiation dose, total acquisition time, mediastinal artefacts, and image quality of each area were reviewed. RESULTS: Mean enhancement values in the ascending and descending aorta were significantly greater with the conventional protocol. Enhancement of the abdominal aorta, iliac arteries, IVC, liver, spleen, and kidneys was significantly greater with the revised protocol. Mediastinal streak artefacts were present in all conventional protocol images and absent in all revised protocol images. Image quality using the revised protocol was significantly better (p < 0.002). The mean effective radiation dose was significantly lower (p = 0.005), and image number reduced (p < 0.001). CONCLUSION: The revised triphasic injection single-pass whole-body imaging protocol was superior to the conventional protocol using 64-MDCT. It enabled better vascular and abdominal parenchymal imaging with reduction in radiation dose and image overload.

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AIM: To evaluate the effect of physical activity on the structural, morphological, and metabolic characteristics of the gastrocnemius muscle in familial Mediterranean fever (FMF) patients, utilizing quantitative (31)P magnetic resonance spectroscopy (MRS), in order to elucidate the mechanism of their exertional leg pain. MATERIALS AND METHODS: Eleven FMF patients suffering from exertional leg pain (eight male, three female; mean age 33 years) and six healthy individuals (three male, three female; mean age 39 years) constituted the control group. All of the participants underwent magnetic resonance imaging (MRI) and non-selective (31)P MRS (3 T) of the leg muscles before and after graded exercise on a treadmill. Phosphocreatine (PCr):inorganic phosphate (Pi), PCr:adenosine triphosphate (ATP) ratios and the intracellular pH of the leg muscles were measured using (31)P MRS. RESULTS: For both groups, normal muscle mass with no signal alterations was observed on the MRI images after exercise. The normal range of pre- and post- exercise MRS muscle parameters was observed in both groups. However, the intracellular pH post-exercise, was significantly higher (less acidic) in the FMF group compared to the control group [pH (FMF) = 7.03 ± 0.02; pH (control) 7.00 ± 0.02; p < 0.0006]. CONCLUSIONS: The finding of a less prominent, post-exercise acidification of the gastrocnemius muscle in this FMF patient group suggests a forme fruste of glycogenosis. This preliminary observation should be further investigated in a future, larger-scale study.

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OBJECTIVES: Familial Mediterranean fever (FMF) is characterized by recurrent episodes of fever, peritonitis, arthritis, and pleuritis, caused by neutrophil-induced sterile serositis. Another clinical manifestation in patients with FMF is exertional leg and ankle pain that appears after minor exercise, for which the underlying mechanism is obscure. The purpose of the current study was to feature distal leg changes in FMF patients complaining of exertional leg pain, using magnetic resonance imaging (MRI). METHODS: Eleven patients with FMF who suffer from exertional leg pain (eight males, three females; mean age 33 years) and six unaffected controls (three males, three females; mean age 39 years) underwent MRI (3 T) of the ankle, including conventional T1 and T2 with fat saturation sequences, before and after graded exercise on a treadmill. Clinical and genetic data and sacroiliac radiographs were obtained. RESULTS: Ten patients (91%) with FMF but none of the control group had signs compatible with enthesitis of the Achilles tendon, long plantar ligament, or the plantar fascia (including enthesophytes, erosions, and bone marrow oedema). Nine patients (80%) had radiographic signs of sacroiliitis on the pelvic radiograph. CONCLUSIONS: Exertional leg pain in FMF patients, shown to be associated with signs of enthesopathy on imaging, may be included within the spectrum of spondyloarthropathy.

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PURPOSE: To assess the CT features of sealed rupture of abdominal aortic aneurysm. PATIENTS AND METHODS: We reviewed the CT scans of six index cases obtained over a 3 year period with a sealed rupture of an abdominal aortic aneurysm and those reported in the literature over a 21 year period. CT scans were reviewed for aneurysm size, the presence of a draped aorta and adjacent vertebral erosion. A group of consecutive patients with non-ruptured abdominal aortic aneurysm, referred for endovascular aneurysm repair during the same 3 year period constituted the control group. RESULTS: In the study group of 31 patients the mean size of the aneurysm was 6.24 +/- 2.01 cm, compared to 6.01 +/- 0.99 cm in the control group, without statistically significant difference (t = 0.75, df = 97, P = 0.46). A draped aorta was detected in all patients with a sealed rupture. Vertebral erosion was present in all our six, but mentioned in only 14 of the cases reported. CONCLUSION: A sealed rupture of an abdominal aortic aneurysm can occur in relatively small aneurysms. A draped aorta and adjacent vertebral erosion are characteristic CT signs of such a rupture.

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Intravenous leiomyomatosis is a rare, benign neoplasm of the uterine, affecting adult women. We report two cases in whom intravenous leiomyomatosis extended through the inferior vena cava into the right heart chambers and the pulmonary artery. Both patients underwent staged operation with excision of the cardiac and primary tumour. The differential diagnosis of a right atrial mass in middle-aged women should include intravenous leiomyomatosis.

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AIM: To evaluate the prevalence and localization of the deposition of submucosal fat, the "fat halo sign" (FHS), using computed tomography (CT) in the bowel wall of patients with Crohn's Disease, and to assess its relation to the duration of the disease. MATERIALS AND METHODS: The abdominal CT examinations of 100 consecutive patients were reviewed for the presence of the FHS in the bowel wall. A measurement of less than -10HU was regarded as indicative of fat. CT findings were correlated with the duration of the disease and statistically tested by simple regression analysis. The patients were divided into two groups: group A included 26 patients with a disease duration of less than 1 year and group B included 73 with a longer disease duration. In one patient disease duration was unknown. To test the relationship between disease duration and FHS the cumulative number of FHS positive and negative patients was plotted against disease duration. RESULTS: The FHS was present in 17 of the 100 patients in 20 bowel segments, mainly in the ileum (10) and the ascending colon (8). The FHS was present in 3.8% in group A and in 21.9% in group B (p<0.0375). CONCLUSION: The FHS was present in 17% of patients with CD. Its location was mainly in the terminal ileum and ascending colon, typical sites of the disease. Its prevalence was significantly duration dependent.

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Helical computed tomography (CT) has an important role in the evaluation of a wide range of congenital and acquired thoracic abnormalities. The development of advanced computerized reformations enables the generation of bronchographic and bronchoscopic images of the tracheobronchial tree, as well as angiographic images of pulmonary arteries and veins. Additionally, it provides coronal and sagittal reconstruction imaging of parenchymal abnormalities. This information is obtained by a 20-30s procedure on a typical single channel system, which makes helical CT an optimal technique for the evaluation of patients undergoing major upper airways and thoracic interventions. The recent introduction of multisection CT scanners allows faster imaging of patients with thinner collimation, thus improving spatial resolution along the longitudinal (z) axis of the patient along with reduction of motion artefacts. This article demonstrates the use of dual and quad-section helical CT in the postoperative evaluation of patients undergoing laryngo-tracheal and thoracic interventions, including laryngoplasty, tracheal endoscopic laser ablation, lobectomy, pneumonectomy, lung transplantation, sleeve resection, pulmonary angioplasty, and pulmonary artery thromboendarterectomy. Emphasis is given to the additive value of using computerized reformations over axial images, especially for delineation of complex postoperative anatomical details in the tracheobronchial tree and pulmonary vasculature.

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We present two cases of an extrapleural hematoma, on a follow-up chest X-ray after coronary artery bypass surgery using an internal mammary artery (IMA). In both cases, the finding was disclosed on a routine chest film obtained 1 month post-operatively, in a patient who was either asymptomatic or had nonspecific symptoms. Follow-up chest films showed spontaneous resolution in both patients. We emphasize the recognition and significance of such a self-limited post-operative radiological finding.

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OBJECTIVE: Our purpose was to evaluate the role of post-operative helical computed tomography (CT) and computerized reformations in patients after laryngo-tracheal segmental resection with anastomosis. METHODS: Helical CT and computerized reformations were obtained in 11 consecutive patients who underwent laryngo-tracheal resection with anastomosis for obstruction or stenosis caused by longstanding intubation or tracheostomy. Post-operative computer assisted cross-sectional area, coronal and sagittal diameter measurements at the level of maximal narrowing of the trachea were compared with clinical assessment in all patients. The additive value of various coronal and sagittal computerized reformations over axial images was subjectively evaluated by a consensus of a thoracic radiologist and a neuroradiologist who were blinded to clinical information. RESULTS: Various degrees of restriction in daily activities were reported by patients with cross-sectional area narrowing of more than 50%, by 4/6 patients with cross-sectional area of less than 90mm(2), by 4/5 and 4/6 patients with coronal or sagittal narrowing of more than 25% respectively, and by 4/5 patients with sagittal diameter of less than 12mm. All five patients with cross-sectional area stenosis of less than 50% assessed themselves as 'asymptomatic'. Sagittal multi-planar and volume rendering reformations clarified or added additional information over axial images in all six patients with significant cross-sectional area stenosis (>50%). Volume rendering scores were significantly higher than minimal intensity projection reformations (P=0.01). CONCLUSION: Our preliminary results suggest that CT-based cross-sectional area and diameter measurements of the trachea represent a clinically helpful tool for post-operative evaluation of patients with tracheoplasty. The need for post-operative endoscopy may be obviated in some cases.

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OBJECTIVE: The purpose of this study was to determine the prevalence of the juxtaphrenic peak after upper lobectomy in a large number of consecutive patients. MATERIALS AND METHODS: Available chest radiographs of 172 of 199 sequential patients who had undergone upper lobectomy in a university hospital were evaluated for the presence of a juxtaphrenic peak. The study included 98 cases with right upper lobectomy and 74 with left upper lobectomy. Radiographs were grouped in three postoperative periods: period I, within 7 days after lobectomy (n = 142); period II, between 8 and 30 days (n = 113); and period III, 31 days or more after lobectomy (n = 101). Four experienced radiologists in consensus determined the prevalence of the "juxtaphrenic peak sign," in relation to age, sex, side of lobectomy, positioning (erect or supine), presence of juxtadiaphragmatic abnormalities, and time interval since surgery. RESULTS: The prevalence of the juxtaphrenic peak sign gradually increased from 40.6% in period I to 71.9% in period III after right upper lobectomy (p < 0.01), and from 19% to 47.7%, respectively, after left upper lobectomy (p < 0.01). Its overall prevalence was significantly higher after right upper lobectomy (58.2%) than after left upper lobectomy (40.5%) (p = 0.02), and on erect chest films (51.4%) than on supine ones (28.9%). CONCLUSION: The prevalence of the juxtaphrenic peak sign increases gradually during the weeks following lobectomy. It is more frequent on erect films and after right upper lobectomy. The juxtaphrenic peak may serve as an additional useful radiologic sign suggesting upper lobectomy.

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AIM: Sinus X-rays are still frequently used in the evaluation of paranasal sinusitis. Many radiology departments nowadays provide the referring doctors with a single Waters' projection. Our purpose was to evaluate the diagnostic accuracy of a single Waters' view vs high resolution computed tomography (CT) in the diagnosis of paranasal sinusitis. SUBJECTS AND METHODS: A total of 134 patients with suspected paranasal sinusitis underwent a Waters' view X-ray and high resolution CT on the same day. The radiographs were evaluated independently by nine experienced radiologists, who observed each sinus separately. Sensitivity, specificity, accuracy, positive and negative predictive values were calculated for each sinus and for each observer, using the CT findings as a 'gold standard'. RESULTS: The weighted mean sensitivity for diagnosis of any abnormality in the maxillary sinus was 67.7%, specificity 87.6%, accuracy 78.6%, positive predictive value 82.5% and negative predictive value 76.9%. For this sinus the variation between observers was small, however, the sensitivity for diagnosis of any disease in the frontal and ethmoid sinuses varied widely between observers (range 1.9-54.0% and 0-58.9%, respectively). The sensitivity for the sphenoid sinus was very low (range 0-3.8%), even in radiographs which seemed to demonstrate it well. CONCLUSION: The Waters' view has its limits in the diagnosis of sinusitis of the maxillary sinuses and its contribution for diagnosing lesions in the remaining sinuses is very poor. Whenever access to CT is available, a low dose high-resolution CT study of the paranasal sinuses is highly recommended.Konen, E. (2000). Clinical Radiology55, 856-860.

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Rupture of the myocardial free wall is an infrequent complication of acute myocardial infarction. Unless it occurs in a space confined by pericardial adhesions, only surgical emergency repair of ruptured myocardium can prevent death. In this paper we report the case of an 81-year-old woman who was admitted to the emergency room with cardiac tamponade, resulting from inferolateral acute myocardial infarction and a subsequent rupture of the right ventricular free wall, with the formation of pericardial thrombus and effusion. The patient refused to undergo any surgical or invasive intervention, and therefore she was only treated conservatively. Nevertheless, her condition improved dramatically, as her blood pressure increased and echocardiography abnormalities almost disappeared. Follow-up echocardiography 7 months post discharge was unremarkable. We believe that this rare case emphasizes that in special circumstances, such as creation of a thrombus that prevents more blood from extravasating, free-wall rupture without surgical repair is compatible with long-term survival.

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OBJECTIVE: Virtual bronchoscopy is a new noninvasive technique that provides an internal view of the tracheobronchial tree. The purpose of our study was to assess the role of this technique as compared with fiberoptic bronchoscopy in the evaluation of suspected compression or narrowing of the trachea and main bronchi in children. CONCLUSION: Preliminary results suggest that virtual bronchoscopy may have a useful complementary role to fiberoptic bronchoscopy in evaluation of the tracheobronchial tree of children.

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OBJECTIVE: Our purpose was to describe the use of CT angiography and three-dimensional (3D) reconstruction in the diagnosis of superior mesenteric artery syndrome in three patients. CONCLUSION: CT angiography combined with 3D reconstructions is a noninvasive technique that may have a complementary diagnostic role similar to that of angiography in patients with a classic clinical presentation suggestive of superior mesenteric artery syndrome. CT angiography combined with 3D reconstructions should be considered in patients who might otherwise require angiography.

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