Showing 11 results for Computed Tomography
Kazemi Khaledi A, Taghizadeh M,
Volume 66, Issue 8 (11-2008)
Abstract
Background: Multislice computed tomography (MSCT) is a noninvasive method of detecting coronary artery disease (CAD). The purpose of the present study was to investigate the accuracy of 64-slice MSCT (64-MSCT) in daily practice, without patient selection.
Methods: Sixty-four consecutive suspected CAD patients underwent both 64-MSCT and quantitative coronary angiography (QCA). The CT system The mean time span between MSCT and QCA was 7.2±3.9 days. For the 64-MSCT, detection or exclusion of CAD, defined as one or more areas of >50% stenosis within major epicardial coronary arteries, the sensitivity, specificity, diagnostic accuracy, positive predictive value (PPV), and negative predictive value (NPV) were evaluated both per patient and per segment.
Results: Sixty-one of the 64 coronary CT angiograms (95%) were of diagnostic image quality. QCA showed significant CAD in 64% (39/61) of the patients, with the other 36% (22/61) showing nonsignificant disease or no disease. Sensitivity, specificity, accuracy, PPV, and NPV of 64-MSCT per patient were 92%, 86%, 90%, 92% and 96%, respectively. By the per-segment analysis, 695 of 791 coronary artery segments were assessable (88%). Of these, 64-MSCT showed a sensitivity of 80%, specificity of 92%, accuracy of 90%, PPV of 65%, and NPV of 96%, respectively, in detecting CAD.
Conclusions: Both per patient and per segment analyses for coronary 64-MSCT showed a higher diagnostic accuracy than QCA. This suggests 64-MSCT should primarily be used for risk stratification on a per patient basis as a noninvasive gate-keeper diagnostic method.
Sagheb S, Tarzamni Mk, Javadrashid R, Zomorodi A, Bahluli A,
Volume 67, Issue 8 (11-2009)
Abstract
Background: In kidney transplantation decision about the proper kidney donation is different between surgeons, but simple vasculature anatomy and a kidney without abnormalities are the most important reasons of choosing a kidney. Therefore complete assessment of renal vessels of a live donor with noninvasive techniques is a necessity for nephrectomy. For delineation of the kidney vasculature anomalies and urinary system abnormalities, Multi-Detector CT seems to be excellent method for evaluation.
Methods: In this study 59 live donors were assessed with Multi-Detector CT Angiography. After injection of contrast media, we acquired images with 0.6 mm slice thickness. Processing and three dimentional reconstructions were done and the accessory arteries, early branching of main renal artery, the number of main renal vessels and the ureters were assessed. Findings were compared with the nephrectomy results.
Results: In Multi-Detector CT Angiography the prevalence of accessory renal artery was 3/4% with 98% accuracy, early branching of main renal artery was 8/4% with 100% accuracy. Multiplicity of renal veins was seen in 8/4% of donors with 98% accuracy. Duplicated ureter was not seen in any of the donors.
Conclusions: The accuracy of CT Angiography is 95% for depicting accessory renal artery and multiple renal artery and 100% for early branching. These results were comparable with findings in conventional angiography. Studies showed this method more valuable than M.R. Angiography and digital subtraction angiography. It is less invasive and can be named as the gold standard method in the diagnosis of anomalies of vessels & collecting system in live donors.
Lotfinia I, Ghavami M, Haddadi K, Vahedi P,
Volume 68, Issue 2 (5-2010)
Abstract
Background: Pedicular screws are currently the gold standard of internal fixation of spinal column. Pedicular screws have their own complications, however the surgeon should be aware of morphometery of pedicles, as well as the anatomy of surrounding neural structures to minimize these risks. No national study has ever examined the physical characteristics of lumbar pedicles and this study is unique for this purpose.Methods: This study covers the patients undergoing lumbar spinal CT-scanning due to variable causes. 25 vertebrae were selected in either gender, 18 years or older and EFilm computer software was employed to measure different diameters of pedicle and the results were analyzed with p≤0.05 regarded as significant.Results: L5 pedicle was the widest (16.8 mm), while L1 was the narrowest (8.25 mm).this figure was 8.82, 10.48 and 12.86 mm for L2, L3, L4 respectively. Longitudinal depth of pedicle was 47.98, 48.68, 50.42, 48.32 and 47.8 mm for L1, L2, L3, L4, L5 respectively.Statistically significant differences were found between some dimensions detected in our study and similar studies.
Conclusions: The advantages of pedicular screws and rods to stabilize spinal column are well known. To avoid neurological complications, an understanding of anatomy and pedicle orientation is mandatory. The shape and diameters of pedicles are different base on races. Some differences were found in our study regarding pedicle dimensions.
Varshosaz M, Sharifi S,
Volume 68, Issue 7 (10-2010)
Abstract
Background: Paranasal sinus disease is one of the most common problems of patients that refer to ENT centers. Adding to clinical examination imaging plays an important role in diagnosis and treatment. Also the imaging of paranasal sinuses is necessary before surgery. Although computed tomography is the modality of choice for these areas, it has some disadvantages which the most important one is its high patient's dose. The aim of this study is the comparison between cone beam volumetric tomography and conventional computed tomography computed tomography, in evaluation of these areas.
Methods: In this descriptive-analytic study Coronal computed tomography imaged and cone beam volumetric tomography images were performed for 40 patients referred to ENT department of Amir Aelam Hospital in Tehran, Iran. Computed tomography images were observed by general radiologist and cone beam volumetric tomography images by Maxillofacial radiologist and their results' were recorded. Also ENT surgeon recorded her observations during surgery. Data were analyzed using McNemar test with Kappa and weighted Kappa agreement coefficient.
Results: No statistical difference was shown between the efficacy of computed tomography and cone beam volumetric tomography in evaluation of paranasal sinuses (p> 0.05).
Conclusion: As there was not any difference between conventional computed tomography and cone beam volumetric tomography in the assessment of paranasal sinuses and additional advantages of the later, cone beam volumetric tomography is suggested for paranasal sinus imaging before surgery.
Parsa Hosseini M, Soltanian-Zadeh H, Akhlaghpoor Sh,
Volume 68, Issue 12 (3-2011)
Abstract
Background: Chronic Obstructive Pulmonary Disease (COPD) is one of the most prevalent pulmonary diseases. Use of an automatic system for the detection and diagnosis of the disease will be beneficial to the patients' treatment decision-making process. In this paper, we propose a new approach for the Computer Aided Diagnosis (CAD) of the disease and determination of its severity axial CT scan images.
Methods: In this study, 24 lung CT scans in full inspiratory and expiratory states were performed. Variations in
the normalized pattern of the lungs' external parenchyma were exploited as a feature for COPD diagnosis.Subsequently, a Bayesian classifier was used to classify variations into two normal and abnormal patterns for the discrimination of patients and healthy individuals. Finally, the accuracy of the classification was assessed
statistically.
Results: With the proposed method, the lungs parenchymal elasticity and air-trapping
were determined quantitatively. The more this feature tended to zero, the more severe air-trapping and obstructive pulmonary disease is. By analyzing CT
images in the healthy and patient groups, we calculated the hard threshold for the diagnosis of the disease. Clinical results tested by the
mentioned method, suggested the effectiveness of this approach.
Conclusion: In regard to the challenges of COPD diagnosis, we propose a new computer-aided design which may be helpful to physicians for a more accurate diagnosis of the disease. Moreover, this severity scoring algorithm may be
useful for targeted disease management and risk-adjustment.
R Afzalipour, Sr Mahdavi, H Khosravi, A Neshasteh-Riz, A Fatemeh Hosseini,
Volume 71, Issue 2 (5-2013)
Abstract
Background: Today, a CT scan examination play an important role in disease diagnosis and thus allocates a significant dose of medical X-ray examinations. One of the important principles in the use of ionizing radiations is to observe radiation protection principles. Evaluating patient's absorbed dose and implementing the strategies for reducing dose are prior in safety issues. To achieve this purpose, sufficient studies should be performed in this regard. Therefore, patient's absorbed dose and the factors affecting have been studied in this research. This study aims to present and develop an acceptable level of absorbed dose in CT scan examinations.
Methods: Diagnostic reference dose level in the adult age group (older than 15 years) has been studied in eleven CT scan centers in Tehran. For this purpose, CT scan examinations prevalent in above-mentioned centers were chosen and Weighted Computed Tomography dose index (CTDIw) and dose length product (DLP) parameters were studied. Standard phantoms with 16 and 32 diameters of Polymethylmethacrylate (PMMA) origin have been used in the centers for CT scan calibration process. CTDIw third quartile has been considered as the diagnostic reference dose level (DRL).
Results: Rate of diagnostic reference dose in the adult age group (older than 15 years) for the head, sinus, lungs, abdomen and pelvis are 50.87, 38.27, 8.05 and 9.11 mg, respectively. Dose measurements made in this survey have been used to set up local DRLs and can be used as a template for national DRLs.
Conclusion: Value of diagnostic reference dose for the head examinations is more than the other parts and diagnostic reference dose in Tehran city in the Adult age group and the protocols compared is less than national reference dose.
Ayoub Amirnia, Parinaz Mehnati , Nasrollah Jabbari ,
Volume 75, Issue 2 (5-2017)
Abstract
Background: Due to the presence of radiosensitive organs in the abdominopelvic region and increasing the number of requests for CT scan examinations, concerns about increasing radiation doses in patients has been greatly elevated. Therefore, the goal of this study was to determine the absorbed dose of radiosensitive organs and the effective dose in patients underwent abdominopelvic CT scan using ImPACT CT patient dosimetry Calculator (version 1.0.4, Imaging Performance Assessment on Computed Tomography, www.impactscan.org).
Methods: This prospective cross-sectional study was conducted in Imam Reza Hospital from November to February 2015 February 2015 in the Imam Reza Hospital, in Urmia, Iran. The demographic and dosimetric information of 100 patients who underwent abdominopelvic CT scan in a 6-slice CT scanner were obtained through the data collection forms. The demographic data of the patients included age, weight, gender, and BMI. The dosimetric parameters included pitch value, CT dose volume index (CTDIvol), dose-length product (DLP), tube voltage, tube current, exposure time, collimation size, scan length, and scan time. To determine the absorbed dose of radiosensitive organs and also the effective dose in patients, ImPACT CT patient dosimetry calculator was used.
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Results: The results of this study demonstrated that the mean and standard deviation (SD) of patients' effective dose in abdominopelvic CT scan was 4.927±0.164 mSv. The bladder in both genders had the greatest mean organ dose, which was 64.71±17.15 mGy for men and 77.56±18.48 mGy for women (P<0.001).
Conclusion: The effective dose values of this examination are in the same range as previous studies, as well as International Commission on Radiological Protection (ICRP) recommendations. However, the radiation dose from CT scan has the largest contribution to the medical imaging. According to the ALARA principle, it is recommended that the scan parameters, especially mAs, should be chosen so that the patient dose is minimum, and the image quality is maximum. Furthermore, other imaging modalities are used as an alternative to the CT scan.
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Daryoush Khorramian , Soroush Sistani , Amin Banaei , Salar Bijari ,
Volume 75, Issue 7 (10-2017)
Abstract
Background: There are several techniques for reducing the delivered dose from CT (Computed tomography) scanning such as the automatic exposure control (AEC). This technique modulates the tube current regarding the patient size and weight. The aim of this study was to estimate the effect of the AEC on the radiosensitive organs effective doses in women undergoing chest CT scanning.
Methods: This study was a cross-sectional, analytical and quantitative study that was performed during 3 months in the imaging section of the Firoozgar educational and therapeutic hospital (belonging to Shahid Beheshti University of Medical Sciences) in the spring of 2017. CT scan exposure parameters were gathered and registered for 54 women undergoing chest CT scan. 25 of these scans were performed using AEC system and 29 of them were performed without using AEC. CT dose indexes in the center and peripheral regions of the standard phantom were calculated using the exposure parameters. Weighted CT dose index was also calculated and effective organ doses were obtained using CT-Expo software, version 2 (Medizinische Hochschule, Hannover, Germany) for two mentioned groups. In addition, noise was measured for these two groups as an image quality parameter.
Results: Calculated weighted CT dose indexes were 9.94 mGy and 12.46 mGy using AEC system and without using AEC, respectively. The calculated effective doses were equal to 5.4 mSv and 6.3 mSv using AEC and without using AEC, respectively. Maximum organ effective doses were 15, 14, 14 and 14 mSv for breast, esophagus, lung and thymus respectively in the non-using AEC system imaging technique.
Conclusion: Our measurements indicated a decrease about 15% in weighted CT dose index (from 12.46 to 9.94 mGy) using AEC system. Beside of this fact, the noise increased about 11.3% (from 4.2 to 4.74) using AEC system. So, it can be said that using of AEC was an effective way for dose reduction in women undergoing chest CT scanning, and the additional noise was in the acceptable range.
Neda Pak , Fateme Zamani, Sara Naybandi Atashi, Anese Saleh Nia,
Volume 78, Issue 6 (9-2020)
Abstract
Background: Central venous catheterization is a procedure that is being performed frequently especially in critical clinical settings. In such conditions, good knowledge of the surface anatomy of venous structures is vital to avoid possible complications which could result in life-threatening situations such as bleeding and pneumothorax. Considering the difference between venous anatomy of children and adults and even among different age groups of children, and the fact that our recent knowledge of anatomy is based on studies performed on non-Iranian population, we decided to evaluate the anatomy of the intrathoracic systemic venous system in adults and children and assess the rate of catheter malposition in children.
Methods: This was a retrospective cross-sectional study performed in Dr. Shariati Hospital and Children Medical Center of Excellence, Tehran, Iran, from April 2016 to August 2019. In our study, the surface location of brachiocephalic vein (BCV) formation, the junction of superior vena cava (SVC) to right atrium and, formation of SVC were examined in 150 contrast-enhanced chest computed tomography (CT) scans in children. They were classified into three groups based on their age (neonates to three years, three to seven years, and seven to ten years). Also, 100 similar CT scans in adults were being studied. The other category which has been evaluated through 130 pediatric X-rays, was the location of the tip of the central venous catheter.
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Results: The formation of BCV was mostly depicted posterior to the sternoclavicular joint in adults while in children it’s located posterior to the medial aspect of the head of clavicle. In adults, the SVC formation was at first intercostal space (ICS) in 52% and second ICS in 29%. In first group of children, SVC was commonly at the level of 2nd costal cartilage (CC), but changed to the first ICS or first CC by increasing age. In adults, junction of right atrium to SVC was at the 3rd CC then 4th CC but in the first group of children was located at the 4th CC that changed to 3rd ICS /3rd CC by increasing age. Also, the tip of central venous catheters was located in the proper position in 74.7% of cases.
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Conclusion: This study indicated the different anatomy of central veins in children and adults which could be a cause for malposed central catheter, so knowing this difference and controlling the tip of the catheter by ultrasound during catheterization could help in avoiding this malpositioning.
Pooya Iranpour , Azadeh Sharifzadeh Yazdi , Rezvan Ravanfar Haghighi , Mahdi Saeedi-Moghadam ,
Volume 79, Issue 4 (7-2021)
Abstract
Background: Since pulmonary angiography is the only non-invasive method for diagnosing pulmonary embolism, the use of radiation reduction methods without affecting the quality of images seems necessary. One of the simplest reasons for unnecessarily increasing of patient exposure is repetitive imaging due to poor image quality. Therefore, it is necessary to identify and eliminate the factors that reduce the image quality, which leads to duplication of imaging or reduced accuracy. In this study, the reasons for decreasing the image quality of pulmonary computed tomography (CT) angiography were investigated.
Methods: This cross-sectional study was performed over a period of 6 months (May to November 2018) in a university-affiliated hospital. Data of 75 patients suspected of pulmonary embolism who were referred for CT angiography were collected. All CT scans were performed by a 16-slice CT scanner (Lights Speed, GE Healthcare) with fixed imaging parameters including 100 kVp and 100 mA. In order to evaluate the adequacy of pulmonary artery enhancement, the Hounsfield unit (HU) of the main pulmonary artery was measured in the aortic arch, upper, and lower segmental parts. Also, 8 factors affecting the image quality were examined.
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Results: The mean HU of the main pulmonary arteries was 312 in the range of 124 to 677. The mean HU in patients with and without pulmonary embolism was 358 and 302, respectively. Most CT images (61%) had poor quality for the diagnosis of pulmonary embolism. Only 2% of the images were acceptable compared to standard images and protocols. Late imaging was the most common quality confounding factor in this study.
Conclusion: A low-quality image reduces the accuracy of the physician's diagnosis that leads to misdiagnosis. Besides, sometimes poor image quality leads to repetitive imaging, which results in increased patient exposure and therefore increased radiation hazards. Therefore, modifiable confounding factors must be identified and corrected which one of the most important ones is wrong imaging timing protocols after contrast injection.
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Mahdi Yadollahzadeh, Nader Rezaei , Mohsen Farrokhpour , Mehdi Azimi, Maedeh Barahman, Mohammad Bahadoram , Amirhossein Forouzanmehr , Seyed Ali Javad Mousavi ,
Volume 81, Issue 6 (9-2023)
Abstract
Background: The realm of diagnosing intrathoracic lesions involves a spectrum of imaging methodologies, among which computed tomography (CT)-scan and magnetic resonance imaging (MRI) stand prominent. In the context of Iran, where there is no study comparing the efficacy of CT-scan and MRI for evaluating intrathoracic lesions, our study endeavors to bridge this gap. Mindful of the nuanced advantages and drawbacks inherent in each method, we aim to conduct a comprehensive comparative analysis of CT-scan and MRI in diagnosing intrathoracic lesions, focusing on patients seeking care at Firoozgar Hospital's pulmonary clinic.
Methods: Embarking on a cross-sectional exploration at Firoozgar Hospital Pulmonary Clinic in Tehran, Iran, our investigative journey unfolded between April 2020 and March 2021. Thirty patients, spanning ages 21 to 69, presenting with intra-thoracic lesions encompassing mediastinal and chest wall anomalies, underwent simultaneous CT scan and MRI examinations. In pursuit of diagnostic certainty, histopathology was ordained as the gold standard, and the ensuing results underwent meticulous scrutiny and analysis utilizing SPSS 23 statistical software.
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Results: Our study cohort comprised 30 patients, averaging 44.83 years (SD=12.71), with males constituting 60% of the population. Delving into the histological reports, CT-scan and MRI accurately diagnosed 25 (83.3%) and 28 (93.3%) cases, respectively, in retrospective analysis. The Kappa matching coefficient for CT-scan stood at 0.783, while for MRI, it soared to 0.912. A notable revelation surfaced as the Kappa matching coefficient for both CT-scan and MRI maintained a robust 0.783 (P<0.001 in all three cases).
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Conclusion: MRI might wield a superior diagnostic prowess compared to CT-scan in evaluating intrathoracic lesions. The robust Kappa matching coefficients endorse a substantial concordance between the two imaging modalities. The implications further beckon contemplation that, in select scenarios, the acquisition of biopsy and histopathology may prove redundant when scrutinizing intrathoracic lesions using the tandem approach of CT-scan and MRI. However, to etch these findings into the annals of medical certainty, a multicenter study endowed with a judicious sample size emerges as an imperative next step.
