Helical Computed Tomography Examinations Research Articles

In Vıvo Evaluatıon Of The Chemıcal Composıtıon Of Urınary Stones Usıng Non-Contrast Helıcal Computerized Tomography

ABSTRACT: 
 Aim:
 To determine the density and chemical structure of renal stones by using in vivo low dose helical computerized tomography.
 Methods:
 79 patients with renal or uretheral stones were included in our study who were going to have extracorporeal shock wave lithotripsy (ESWL) or planned to go through urinary stone surgery due to renal stones. All stone densities were measured in Hounsfield Unit by low dose abdominal non-contrast helical computed tomography examination. Marconi MX 8000 CT system with 4 detectors was used for the CT examination. X-Ray diffractometry was used in the analyses of all stones.
 Results:
 The stone type was found to be one type, and mixed stone in 27 patients. The largest group among the mixed stones included whevellite-weddellite stone with 17 patients. Uric acid stones had the smallest, whevellite stones had the highest density. The difference between the density values of uric acid and cystine stones and the other stone types were statistically significant.
 Conclusion:
 Non-contrast helical computed tomography used in the diagnosis can also be used in the in vivo determination of the stone composition. It can be very helpful to define stone compositions by imaging studies to provide suitable therapeutic alternatives.

Patient-specific fetal radiation dosimetry for pregnant patients undergoing abdominal and pelvic CT imaging.

Accurate estimation of fetal radiation dose is crucial for risk-benefit analysis of radiological imaging, while the radiation dosimetry studies based on individual pregnant patient are highly desired. To use Monte Carlo calculations for estimation of fetal radiation dose from abdominal and pelvic computed tomography (CT) examinations for a population of patients with a range of variations in patients' anatomy, abdominal circumference, gestational age (GA), fetal depth (FD), and fetal development. Forty-four patient-specific pregnant female models were constructed based on CT imaging data of pregnant patients, with gestational ages ranging from 8 to 35weeks. The simulation of abdominal and pelvic helical CT examinations was performed on three validated commercial scanner systems to calculate organ-level fetal radiation dose. The absorbed radiation dose to the fetus ranged between 0.97 and 2.24 mGy, with an average of 1.63±0.33 mGy. The CTDIvol -normalized fetal dose ranged between 0.56 and 1.30, with an average of 0.94±0.25. The normalized fetal organ dose showed significant correlations with gestational age, maternal abdominal circumference (MAC), and fetal depth. The use of ATCM technique increased the fetal radiation dose in some patients. A technique enabling the calculation of organ-level radiation dose to the fetus was developed from models of actual anatomy representing a range of gestational age, maternal size, and fetal position. The developed maternal and fetal models provide a basis for reliable and accurate radiation dose estimation to fetal organs.

"Radiochromic Film Dosimetry Method used to Estimate the Peak Skin Dose During Helical Computed Tomography Examinations of the Head"

"Radiochromic Film Dosimetry Method used to Estimate the Peak Skin Dose During Helical Computed Tomography Examinations of the Head"

The Imaging Performances of Contrast-Enhanced Ultrasound, Computed Tomography, and Magnetic Resonance Imaging for Extrahepatic Cholangiocarcinoma

Objective: To compare the imaging performances of contrast-enhanced ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI), thereby explore their values and significances in clinical practices of diagnosing extrahepatic cholangiocarcinoma. Methods: A total of 56 patients with extrahepatic cholangiocarcinoma were included as research objects. All the patients underwent contrast-enhanced ultrasound examination, enhanced MRI examination, and multi-slice helical CT (MSCT) examination. The major contents of analysis and observation included the location of the lesion, the range, the features of blood flow signal, the echoes of lesions at various phases, the enhancement levels, and the morphology. Then, the tabu search algorithm was applied to reconstruct the images, thereby completing the construction of the image objective function. Results: In terms of histopathological typing, 9 papillary adenocarcinomas, 22 invasive adenocarcinomas, and 25 poorly-to-moderate differentiated adenocarcinomas were found. In terms of ultrasound results, 27 lesions were isoechoic, 23 lesions were hypoechoic, and 6 lesions were hyperechoic. In terms of MRI results, 66% of the patients had hyperechoic lesions during the arterial phase, and 55.1% of the patients had isoechoic lesions during the portal phase. During the delay phase, 30.3% of the patients had isoechoic lesions, and 58.9% of the patients had hyperechoic lesions. Conclusion: Contrast-enhanced ultrasound, CT, and MRI had magnificent values and significance in the clinical diagnosis of extrahepatic cholangiocarcinoma, which could be widely applied in the diagnosis and treatment of extrahepatic cholangiocarcinoma. In addition, the contrast-enhanced ultrasound and CT could be used as an effective supplementary basis for enhanced MRI diagnosis. These three diagnostic methods had respective advantages and could be used in combination.

Diagnostic performance of reformatted isotropic thin-section helical CT images in the detection of superior semicircular canal dehiscence.

Purpose The purpose of this article is to assess the diagnostic performance of computed tomography (CT) reformatted images for detection of superior semicircular canal (SSC) dehiscence. Material and methods Forty-two patients, with sound- and/or pressure-induced vestibular symptoms, and 42 control participants underwent helical CT examination with a highly collimated beam (0.5 mm). Reformatted images of the vestibular labyrinth were obtained in the standard axial and coronal planes (group A images), and in a plane parallel and perpendicular to the SSC (group B images). Diagnostic performance obtained by evaluating the group A images alone and the group B images alone was analyzed by using the area under the receiver operating characteristic curve (AUC). Results The diagnostic performance of group A images was AUC = 0.929 with an overall accuracy of 92.9%. The diagnostic performance of group B images was AUC = 0.988 with an overall accuracy of 98.8%. The evaluation of group B images alone showed an improved diagnostic performance over the group A images alone. Conclusion Thin-section 0.5-mm collimation CT with reformatted images oriented in the plane parallel and perpendicular to the SSC improves diagnostic accuracy in assessing for SSC dehiscence in comparison to CT images with reconstructions limited to traditional axial and coronal planes.

Real time evaluation of overranging in helical computed tomography

Overranging or overscanning increases the dose delivered to patients undergoing helical Computed Tomography examinations. In order to reduce it, nowadays most of the multidetector tomographs close the X-ray beam aperture at the scan extremes. This technical innovation, usually referred to as dynamic or adaptive collimation, also influences the overranging assessment methods. In particular, the film free approach proposed in previous studies is not suitable for these modern tomographs. The present study aims to introduce a new method of estimating overranging with real time dosimetry, even suitable for tomographs equipped with adaptive collimation. The approach proposed is very easy to implement and time saving because only a pencil chamber is required. It is also equivalent in precision and in accuracy to the film based one, considered an absolute benchmark.

Pitfalls and mimickers at 64-section helical CT that cause negative appendectomy: an analysis from 1057 appendectomies

PurposeTo determine the rate of negative appendectomy and clarify the causes of negative appendectomy in patients with clinically suspected acute appendicitis who had surgery after 64-section helical computed tomography (CT). Material and MethodsA retrospective analysis of 1057 patients who had appendectomy after 64-section helical CT was performed to determine the rate of negative appendectomy. The 64-section helical CT examinations obtained with submillimeter and isotropic voxels in the patients with negative appendectomy were analyzed by two readers and compared to clinical, operative and histopathological reports, discharge summaries and original radiology reports. ResultsThe negative appendectomy rate was 1.7% (18/1057). Appendix enlargement (>6 mm) and fat stranding were present in 17 (17/18; 94%) and 6 patients (6/18; 33%), respectively. In 13 patients (13/18; 72%) 64-section helical CT findings were consistent with acute appendicitis. Interpretive errors in original imaging reports were identified in five patients (5/18; 28%). ConclusionThe preoperative use of 64-section helical CT results in a very low rate of negative appendectomy. Patients with negative appendectomy have 64-section helical CT findings consistent with a diagnosis of acute appendicitis in the majority of cases. Interpretive errors are less frequent.

Clinical analysis of endoscopic ultrasonography in preoperative TNM staging of 126 gastric cancer cases

Objective To evaluate the accuracy of endoscopic ultrasonography (EUS) in preoperative TNM staging of gastric cancer.Methods EUS and abdominal helical computed tomography (HCT) were performed one week before the surgery in 126 gastric cancer patients who would receive surgery to determine the depth of tumor invasion (T),lymph node metastasis (N) and distant metastasis (M) stage and which were also compared with pathologic TNM stage after surgery to evaluate the accuracy of EUS in TNM staging.Pairing x2 test was performed for data analysis.Results Compared with pathologic TNM stage after surgery,the accuracy of EUS in T1,T2,T3 and T4 staging of gastric cancer were 84.6％,14/18,82.0 ％ and 85.7％ respectively.The accuracy of EUSin N0,N1,N2 and N3 staging of gastric cancer were 74.2％,75.0％,57.9％ and 5/17 respectively.The accuracy of HCT in N0,N1,N2 and N3 staging of gastric cancer were 80.6％,75.0％,73.7％ and 12/17 respectively.The accuracy of EUS was similar to HCT in N0 and N1 stage.For N2 and N3 stage,HCT was obviously better than EUS (x2 =4.89,P=0.027; x2 =13.88,P＜0.01).The accuracy of EUS and HCT in M1 stage of gastric cancer were 36.4％ and 95.5％respectively,HCT was better than EUS in M1 determination (x2 =7.90,P=0.001).Conclusions The clinical application value of EUS in the preoperative gastric cancer T staging was high,however the accuracy in determining lymph node metastasis N2 and N3 staging and distant metastasis M staging should be improved.In order to acquire more accurate preoperative TNM stage to guide the treatment selection,the combination with HCT examination is necessary. Key words: Stomach neoplasms; Endosonography; Tomography, X-ray computed; Neoplasm staging

Aspectos tomográficos da coluna cervical de equinos

Descreveu-se a anatomia da região cervical de equinos adultos, com base em imagens obtidas no exame de tomografia computadorizada helicoidal realizado em peças anatômicas de equinos adultos. A tomografia computadorizada foi o método de imagem diagnóstica de escolha e possibilita as reconstruções de imagens tridimensionais e em outros planos anatômicos, como sagital e coronal. Todas as imagens foram adquiridas e avaliadas em filtro e janela para tecido ósseo. Observaram-se diferenças anatômicas e as particularidades normais das vértebras, principalmente da região occipitoatlantoaxial, a qual apresenta maior incidência de alterações.

Juvenile idiopathic arthritis with involvement of the temporomandibular joint: the role of image examinations

PURPOSE: Juvenile idiopathic arthritis (JIA) has unknown etiology, and the involvement of the temporomandibular joint (TMJ) is rare in the early phase of the disease. The present article describes the use of computed tomography (CT) and magnetic resonance (MRI) images for the diagnosis of affected TMJ in JIA. CASE DESCRIPTION: A 12-year-old, female, Caucasian patient, with systemic rheumathoid arthritis and involvement of multiple joints was referred to the Imaging Center for TMJ assessment. The patient reported TMJ pain and limited opening of the mouth. The helical CT examination of the TMJ region showed asymmetric mandibular condyles, erosion of the right condyle and osteophyte-like formation. The MRI examination showed erosion of the right mandibular condyle, osteophytes, displacement without reduction and disruption of the articular disc. CONCLUSION: The disorders of the TMJ as a consequence of JIA must be carefully assessed by modern imaging methods such as CT and MRI. CT is very useful for the evaluation of discrete bone changes, which are not identified by conventional radiographs in the early phase of JIA. MRI allows the evaluation of soft tissues, the identification of acute articular inflammation and the differentiation between pannus and synovial hypertrophy.

Aortic Branch Artery Pseudoaneurysms Accompanying Aortic Dissection. Part I. Pseudoaneurysm Anatomy

Small areas of blood flow are sometimes seen within an otherwise thrombosed false lumen on computed tomography (CT) scans of intramural hematomas of the aorta. These are blood-filled spaces that, although they have no apparent communication with the true lumen, appear isodense with the aorta on contrast-enhanced CT scans. The purpose of this report is to describe angiographic and autopsy studies that establish the nature of this entity and describe the principal CT features distinguishing it from a penetrating ulcer. Conventional angiographic and CT aorta findings in two cases with small collections of contrast material within an otherwise thrombosed false lumen of an aortic dissection are discussed. Also examined is another case with pathologic and histologic findings in addition to those of small collections of contrast material within an otherwise thrombosed false lumen of an aortic dissection, which illustrate the pathoanatomy of these lesions. Angiographic and necropsy evidence shows that some of these lesions represent branch artery pseudoaneurysms and, as such, are secondary to an intramural hematoma, not the primary cause of it. Difficulty in demonstrating communication between these collections of contrast material and the adjacent true lumen of the aorta on helical CT examinations and the characteristic location of these lesions along the nonpleural portion of the aortic circumference distinguish them from penetrating ulcers and should suggest the diagnosis of branch artery pseudoaneurysm. Demonstration of a branch artery originating from the contrast collection confirms the diagnosis. These branch artery pseudoaneurysms should be distinguished from penetrating atherosclerotic ulcers.

Certain Background Factors Exhibit an Association With an Increased Risk for Pancreatic Calcification Among Japanese Male Alcoholics

This was a cross-sectional study conducted from April 2003 through March 2004 to investigate the background factors related to pancreatic calcification (PC) in male Japanese alcoholics. Helical computed tomography examination revealed PC in 44 of 263 alcoholics, and this group was further divisible into 3 subgroups: "scant" (n = 24), "moderate" (n = 6), and "extensive" PC subgroups (n = 14). The extensive subgroup was associated with larger daily ethanol consumption (P = 0.05) and high-alcohol beverages, such as whisky (P = 0.02). The moderate subgroup was associated with a longer duration of habitual drinking (P = 0.04), whereas the scant PC group was associated with never having smoked (P = 0.05) and with low-alcohol beverages, such as beer (P = 0.09). None of the 40 subjects with inactive mitochondrial aldehyde dehydrogenase (ALDH2*2 allele) exhibited PC (P = 0.004). Heterozygous alcohol dehydrogenase 2 genotype (ADH2*1/2*2) exhibited an association with the scant subgroup (P = 0.02). The TG12 repeats in the cystic fibrosis transmembrane conductance regulator (CFTR) gene tended to have a weak association with PC. Drinking behavior, smoking status, and genetic backgrounds are associated with PC and are likely to increase the risk for alcoholic chronic pancreatitis.

Nontraumatic Acute Abdominal Pain: Unenhanced Helical CT Compared with Three-View Acute Abdominal Series

To prospectively evaluate and compare the diagnostic accuracy of unenhanced helical computed tomography (CT) for patients with nontraumatic acute abdominal pain with that of traditional abdominal radiography. Institutional review board approval and informed consent were obtained; this study was completed before implementation of the HIPAA. Ninety-one patients (44 men; 47 women; age range, 18-84 years; mean age, 48.5 years) with acute nontraumatic abdominal pain over a 7-month period were referred by the emergency department of one institution. These patients underwent a three-view acute abdominal series (AAS) and unenhanced helical CT. AAS included an upright chest radiograph and upright and supine abdominal radiographs. Unenhanced helical CT images with 5-mm collimation were obtained from the lung bases to the pubic symphysis, without intravenous, oral, or rectal contrast material. AAS and unenhanced helical CT images were each separately and prospectively interpreted by a different experienced radiologist who was blinded to patient history and the images and interpretation of the other examination for each patient. Final diagnosis was established with surgical, pathologic, and clinical follow-up. The sensitivity, specificity, accuracy, positive predictive value, negative predictive value, and positive and negative likelihood ratios were calculated for AAS and unenhanced helical CT. Confidence intervals of 95% were calculated for each value with the standard equation for population proportions. Results of AAS and unenhanced helical CT examinations were compared with chi2 analysis. Among the 91 patients examined, unenhanced helical CT yielded an overall sensitivity, specificity, and accuracy of 96.0%, 95.1%, and 95.6%, respectively. The AAS interpretations yielded an overall sensitivity, specificity, and accuracy of 30.0%, 87.8%, and 56.0%, respectively. The accuracy of unenhanced helical CT was significantly greater than the accuracy of AAS (P < .05). AAS is an insensitive technique in the evaluation of nontraumatic acute abdominal pain in adults. Unenhanced helical CT is an accurate technique in the evaluation of adult patients with nontraumatic acute abdominal pain and should be considered as an alternative to radiography as the initial imaging modality.

Usefulness of helical computed tomography in diagnosing pulmonary vein stenosis in infants.

We investigated the usefulness of helical computed tomography(CT)in the morphological diagnosis of pulmonary vein stenosis, particularly that in infants and small children. In total, 20 helical CT examinations were performed in 10 post-operative cases of Total Anomalous Pulmonary Venous Drainage(TAPVD), 3 cases of single right ventricle, and 1 case of single left ventricle. In all cases, distinct morphological imaging was possible. Pulmonary vein stenosis could be categorized into three types: (1)stenosis from the anastomosis of the common pulmonary vein (CPV)-the left atrium (LA) to the peripheral pulmonary vein; (2) stenosis only at the anastomosis of CPV-LA; and (3) stenosis due to compression by nearby organs. Coronal views by multiplanar reconstruction (MPR) provided morphological information along the up-down direction of the body axis. Morphological diagnosis of pulmonary vein stenosis is important in deciding prognosis and therapeutic regimens, and helical CT was considered useful for such diagnosis in our 14 young patients.

A New, Accurate and Conventional Five-point Method for Quantitative Evaluation of Ascites Using Plain Computed Tomography in Cancer Patients

To assess the exact response of the malignant ascites to the treatment, the objective measurement of the volume of ascites is essential. We have developed a simple method to measure the volume of ascites by using standard abdomino-pelvic computed tomography (CT). The aim of the study is to validate the accuracy of the measurements by comparing them with the standard volume calculation by using 3D-CT. Twelve consecutive patients with cancer who had measurable ascites underwent 15 helical CT examinations. On conventional CT images, the thickness of ascites in centimeters was measured in three planes such as the bilateral subphrenic space (A and B), the bilateral paracolic space (C and D) and the pre-bladder space (E), and the average thickness: (A + B + C + D + E)/5 was then multiplied by the area of standard abdominal cavity in the anterior projection, that was assumed to be 1000 cm(2), to yield the volume of ascites: (A + B + C + D + E) x 200 (ml). The volume of ascites was compared with the exact volume, that was obtained from 3D-CT with the volume rendering method. The volume of ascites measured by the present method and the volume rendering method ranged from 140 to 4040 ml and from 86 to 4279 ml, respectively. The correlation was statistically significant with a correlation coefficient of 0.956 (P < 0.01) using the Spearman's rank correlation. In 13 examinations with the exact volume > or =300 ml, the average ratio of the absolute difference in the volume was 12.9 +/- 13.9% as compared with 62.8 and 162.0% in two examinations with the exact volume < 300 ml. The preliminary study indicated that the present five-point method using a conventional CT was accurate in patients with the volume of ascites > or =300 ml. Because this procedure is simple and easy to perform, it should be feasible in many hospitals for the follow-up of ascites after treatment.

The effect of overscanning on patient effective dose from multidetector helical computed tomography examinations

z overscanning in multidetector (MD) helical CT scanning is prerequisite for the interpolation of acquired data required during image reconstruction and refers to the exposure of tissues beyond the boundaries of the volume to be imaged. The aim of the present study was to evaluate the effect of z overscanning on the patient effective dose from helical MD CT examinations. The Monte Carlo N-particle radiation transport code was employed in the current study to simulate CT exposure. The validity of the Monte Carlo simulation was verified by (a) a comparison of calculated and measured standard computed tomography dose index (CTDI) dosimetric data, and (b) a comparison of calculated and measured dose profiles along the z axis. CTDI was measured using a pencil ionization chamber and head and body CT phantoms. Dose profiles along the z axis were obtained using thermoluminescence dosimeters. A commercially available mathematical anthropomorphic phantom was used for the estimation of effective doses from four standard CT examinations, i.e., head and neck, chest, abdomen and pelvis, and trunk studies. Data for both axial and helical modes of operation were obtained. In the helical mode, z overscanning was taken into account. The calculated effective dose from a CT exposure was normalized to CTDI(free in air). The percentage differences in the normalized effective dose between contiguous axial and helical scans with pitch = 1, may reach 13.1%, 35.8%, 29.0%, and 21.5%, for head and neck, chest, abdomen and pelvis, and trunk studies, respectively. Given that the same kilovoltage and tube load per rotation were used in both axial and helical scans, the above differences may be attributed to z overscanning. For helical scans with pitch = 1, broader beam collimation is associated with increased z overscanning and consequently higher normalized effective dose value, when other scanning parameters are held constant. For a given beam collimation, the selection of a higher value of reconstructed image slice width increases the normalized effective dose. In conclusion, z overscanning may significantly affect the patient effective dose from CT examinations performed on MD CT scanners. Therefore, an estimation of the patient effective dose from MD helical CT examinations should always take into consideration the effect of z overscanning.

Progression of Focal Pure Ground-Glass Opacity Detected by Low-Dose Helical Computed Tomography Screening for Lung Cancer

To clarify the progression of focal pure ground-glass opacity (pGGO) detected by low-dose helical computed tomography (CT) screening for lung cancer. A total of 15,938 low-dose helical CT examinations were performed in 2052 participants in the screening project, and 1566 of them were judged to have yielded abnormal findings requiring further examination. Patients with peripheral nodules exhibiting pGGO at the time of the first thin-section CT examination and confirmed histologically by thin-section CT after follow-up of more than 6 months were enrolled in the current study. Progression was classified based on the follow-up thin-section CT findings. The progression of the 8 cases was classified into 3 types: increasing size (n = 5: bronchioloalveolar carcinoma [BAC]), decreasing size and the appearance of a solid component (n = 2: BAC, n = 1; adenocarcinoma with mixed subtype [Ad], n = 1), and stable size and increasing density (n = 1: BAC). In addition, the decreasing size group was further divided into 2 subtypes: a rapid-decreasing type (Ad: n = 1) and a slow-decreasing type (BAC: n = 1). The mean period between the first thin-section CT and surgery was 18 months (range: 7-38 months). All but one of the follow-up cases of lung cancer were noninvasive whereas the remaining GGO with a solid component was minimally invasive. The pGGOs of lung cancer nodules do not only increase in size or density, but may also decrease rapidly or slowly with the appearance of solid components. Close follow-up until the appearance of a solid component may be a valid option for the management of pGGO.

Pseudolesões hepáticas na tomografia computadorizada helicoidal: ensaio iconográfico

A tomografia computadorizada helicoidal é largamente empregada na avaliação do parênquima hepático e tem grande importância no planejamento clínico e cirúrgico. O fígado é o órgão que mais se beneficia de aquisições helicoidais, em fases diferentes da perfusão do parênquima, pela sua dupla vascularização e pela diferença de aporte sanguíneo entre tumores e parênquima sadio. Entretanto, várias armadilhas diagnósticas podem ser encontradas, dificultando a análise e prejudicando a diferenciação entre lesões verdadeiras e pseudolesões, principalmente aos olhos de radiologistas menos experientes. Essas pseudolesões têm forma, localização e características variadas, podendo simular lesões parenquimatosas. É de fundamental importância que estejamos aptos a reconhecê-las, no sentido de interpretar corretamente as imagens tomográficas. O objetivo deste ensaio é classificar e ilustrar as diversas pseudolesões hepáticas pela tomografia computadorizada helicoidal, com uma breve descrição dessas lesões e com alternativas para diferenciá-las das lesões do parênquima.

Application of helical computed tomographic angiography with differential color imaging three-dimensional reconstruction in the diagnosis of complicated congenital heart diseases

J Thorac Cardiovasc Surg 2003;125:36-9

Tomografia computadorizada helicoidal dos seios paranasais na criança: avaliação das sinusopatias inflamatórias

Neste estudo foi feita avaliação retrospectiva de 71 casos selecionados de pacientes pediátricos, maiores de um ano e menores de sete anos, que realizaram exame de tomografia computadorizada helicoidal dos seios paranasais no período de março de 1997 a abril de 1998, apresentando quadro clínico de sinusopatia inflamatória aguda recorrente e sinusopatia inflamatória crônica. Foram correlacionados os quadros clínicos com os achados da tomografia computadorizada helicoidal, avaliando a pneumatização dos seios paranasais, os complexos óstio-meatais, as variações anatômicas, o estado da superfície mucosa e a extensão lesional. Os achados tomográficos de maior prevalência foram o velamento total ou parcial de uma ou mais cavidades paranasais (92,9%), seguido da hipertrofia da mucosa de revestimento (67,6%). Houve, na maioria dos casos, associação entre a sinusopatia inflamatória e a obstrução dos complexos óstio-meatais (53,5%). As variações anatômicas foram identificadas já a partir de um ano, com predomínio dos desvios do septo nasal (14,1%), estando correlacionadas às sinusopatias inflamatórias em cerca de 71% dos pacientes.