Ultra-high-resolution Computed Tomography Research Articles

Ultra-High-Resolution Computed Tomography of the Lung: Image Quality of a Prototype Scanner.

PurposeThe image noise and image quality of a prototype ultra-high-resolution computed tomography (U-HRCT) scanner was evaluated and compared with those of conventional high-resolution CT (C-HRCT) scanners.Materials and MethodsThis study was approved by the institutional review board. A U-HRCT scanner prototype with 0.25 mm x 4 rows and operating at 120 mAs was used. The C-HRCT images were obtained using a 0.5 mm x 16 or 0.5 mm x 64 detector-row CT scanner operating at 150 mAs. Images from both scanners were reconstructed at 0.1-mm intervals; the slice thickness was 0.25 mm for the U-HRCT scanner and 0.5 mm for the C-HRCT scanners. For both scanners, the display field of view was 80 mm. The image noise of each scanner was evaluated using a phantom. U-HRCT and C-HRCT images of 53 images selected from 37 lung nodules were then observed and graded using a 5-point score by 10 board-certified thoracic radiologists. The images were presented to the observers randomly and in a blinded manner.ResultsThe image noise for U-HRCT (100.87 ± 0.51 Hounsfield units [HU]) was greater than that for C-HRCT (40.41 ± 0.52 HU; P < .0001). The image quality of U-HRCT was graded as superior to that of C-HRCT (P < .0001) for all of the following parameters that were examined: margins of subsolid and solid nodules, edges of solid components and pulmonary vessels in subsolid nodules, air bronchograms, pleural indentations, margins of pulmonary vessels, edges of bronchi, and interlobar fissures.ConclusionDespite a larger image noise, the prototype U-HRCT scanner had a significantly better image quality than the C-HRCT scanners.

Multislice Computed Tomography Overestimates Superior Semicircular Canal Dehiscence Syndrome

We assessed the prevalence of superior semicircular canal dehiscence (SSCD) through examination of ultrahigh-resolution computed tomography (CT) scans of the temporal bone and attempted to verify the correspondence between a radiologic diagnosis of SSCD and clinical signs of SSCD syndrome. A prospective study was carried out on 191 consecutive patients who underwent temporal bone ultrahigh-resolution CT scans. Cases that matched the radiologic diagnosis of SSCD were subsequently referred for a comprehensive audiological evaluation that might enable a final diagnosis of SSCD syndrome. Among the 191 patients, 17 had a radiologic diagnosis of SSCD, which was bilateral in 5 cases, for a total of 22 SSCD cases, with a prevalence rate of 5.8%. In 2 of the 17 patients, the audiological examination revealed signs and symptoms indicative of SSCD syndrome, with a total prevalence rate of 0.5%. Our data confirm that the radiologic diagnosis of SSCD, performed by mean thin-section CT scans reformatted in the plane of the superior semicircular canal, is not necessarily related to the clinical presentation of SSCD syndrome. Our study also showed a prevalence rate of SSCD syndrome that was similar to the prevalence of SSCD reported from studies of histologic specimens.

La déhiscence du canal semi circulaire supérieur

Introduction : Superior semicircular canal dehiscence is a rare entity witch is recently described. The common symptom is pressure-induced vertigo.Patients and methods: we report 2 cases of superior semicircular canal dehiscence identified by computed tomography (CT) of the petrous bone in patients with mixed hearing loss and a normal tympanic membrane.Results: Superior semicircular canal dehiscence was bilateral in 1 patient.Mixed hearing loss with a normal tympanic membrane without vertigo was the presenting manifestation in all cases. Ultrahigh-resolution CT of the petrous bones with coronal and sagittal sections provided the diagnosis of superior semicircular canal dehiscence.Conclusion: Mixed hearing loss with a normal tympanic membrane should suggest superior semi circular canal dehiscence. Coronal and sagittal CT sections less than 1 mm in thickness establish the diagnosis.Key words : Superior semicircular canal, dehiscence, hearing loss.

Fire victim identification by post-mortem dental CT: Radiologic evaluation of restorative materials after exposure to high temperatures

Objectives The aim of this study was to evaluate the use of high resolution CT to radiologically define teeth filling material properties in terms of Hounsfield units after high temperature exposure. Methods 122 human molars with 10 different filling materials at defined filling diameters were examined. The teeth were CT scanned both before and after the exposure to different temperatures. After image reconstruction, the teeth and filling materials were analyzed regarding their morphology and Hounsfield units (HU) using an extended HU scale. Results The majority of filling materials diminished in size at temperatures ≥400 °C. HU values were stable for all materials up till 200 °C, and only slightly changed up to 600 °C. Cerec, Dyract and dentin showed only minor changes in HU at all temperatures. The other materials, inclusive enamel, showed specific patterns, either increasing or decreasing in HU with increasing temperatures over 600 °C. Conclusions Over 600 °C the filling materials show specific patterns that can be used to discriminate filling materials. Ultra high resolution CT may improve the identification processes in fire victims. Existing 3D visualization presets for the dentition can be used until 600 °C and have to be optimized for bodies exposed to higher temperatures.

Standardization in CT Terminology: A Physicist's Perspective

HomeRadiologyVol. 241, No. 3 PreviousNext Reviews and CommentaryEditorialsStandardization in CT Terminology: A Physicist's PerspectiveCynthia H. McColloughCynthia H. McColloughAuthor Affiliations1From the Department of Radiology, Mayo Clinic and Mayo Foundation, 200 First St SW, Rochester, MN 55905. Received May 26, 2006; final version accepted May 30.Address correspondence to the author (e-mail: [email protected]).Cynthia H. McColloughPublished Online:Dec 1 2006https://doi.org/10.1148/radiol.2413060924MoreSectionsFull textPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked In References1 Kalra MK, Saini S. Standardized nomenclature and description of CT scanning techniques. Radiology 2006;241(3):657–660. Link, Google Scholar2 Kalender WA. Spiral or helical CT: right or wrong [letter]. Radiology 1994;193(2):583. Link, Google ScholarArticle HistoryPublished in print: 2006 FiguresReferencesRelatedDetailsCited ByEuropean Radiology, Vol. 24, No. 1Radiation Protection Dosimetry, Vol. 157, No. 4Journal of the ICRU, Vol. 12, No. 1Physics in Medicine and Biology, Vol. 54, No. 7Health Physics, Vol. 97, No. 4Otolaryngologic Clinics of North America, Vol. 40, No. 3Recommended Articles Demystifying the CT Radiation Dose SheetRadioGraphics2022Volume: 42Issue: 4pp. 1239-1250Effect of Localizer Radiography Projection on Organ Dose at Chest CT with Automatic Tube Current ModulationRadiology2016Volume: 282Issue: 3pp. 842-849Digital Breast Tomosynthesis: Physics, Artifacts, and Quality Control ConsiderationsRadioGraphics2019Volume: 39Issue: 2pp. 413-426CT Angiography of the Aorta: Contrast Timing by Using a Fixed versus a Patient-specific Trigger DelayRadiology2019Volume: 291Issue: 2pp. 531-538CT Angiography of the Aorta: Prospective Evaluation of Individualized Low-Volume Contrast Media ProtocolsRadiology2016Volume: 280Issue: 3pp. 960-968See More RSNA Education Exhibits Demystifying the CT Dose Sheet and Image HeadersDigital Posters2020Improved Delineation of Brain Perforating Arteries in Brain CTA by Ultra High-Resolution CT: What the Radiologist and Radiology Technologist Need to KnowDigital Posters2019Effect of Connecting Part of Extension Table on Radiation Dose and Image Quality at Head CT ScanDigital Posters2018 RSNA Case Collection Trans-scaphoid Perilunate DislocationRSNA Case Collection2020TrichobezoarRSNA Case Collection2021latrogenic tracheal perforation from urgent cricothyrotomyRSNA Case Collection2020 Vol. 241, No. 3 Metrics Altmetric Score PDF download

Morphological Analysis of Pulmonary Peripheral Airways by Ultra High-resolution CT

Morphological Analysis of Pulmonary Peripheral Airways by Ultra High-resolution CT

Computed tomographic measurement of macroporosity in chisel-disk and no-tillage seedbeds

Methods for evaluating soil conditions as influenced by tillage are often limited to analysis of bulk samples. The application of medical computed tomography (CT) to the characterization of tillage effects on soil provides an alternative tool for measurement since it is at a more detailed scale. The objective of this study was to compare soils under conventional and no-tillage (NT) systems using X-ray CT. Chisel-disk-disk (CDD) conventional tillage and NT systems were compared for a Mexico silt loam (fine, smectitic, mesic Aeric Vertic Epiaqualfs) soil. Five replicate soil cores (75 mm long by 75 mm diameter) were collected from each treatment. Two CT systems were used in this study: a medical CT scanner (MCT, 1 mm thick scans) and an ultra-high resolution CT scanner (UHCT, 0.1 mm thick scans). Significantly higher soil density was found for the NT treatment using the MCT scanner ( P=0.05). Data from the UHCT scanner were used to compare the effects of scan thickness and to evaluate macropore characteristics. Macropore area was significantly higher ( P<0.001) for CDD as compared to the NT treatment: 11 versus 5%. The number of macropores in the CDD treatment were twice those in NT; their perimeter was 62% longer; and their circularity was 94% of that for pores from the NT tillage treatment. The macropore box-counting fractal dimension ( D) was significantly greater ( P<0.001) for CDD ( D=1.44) as compared to the NT treatment ( D=1.26), reflecting the greater space-filling behavior of the CDD treatment. This study shows that the UHCT scanner can characterize differences in soil macroporosity more precisely than standard MCT scanners. The use of ultra-high resolution tomography can aid in the discrimination of differences between seedbeds created by different tillage systems.

Noninvasive Assessment of Bone Density and Structure Using Computed Tomography and Magnetic Resonance

For several reasons, including low cost and radiation dose, simplicity, and the ability to image several skeletal sites, dual X-ray absoptiometry (DXA) is the most widely employed technique for diagnostic and serial assessment of integral bone mass in osteoporosis and other metabolic bone diseases. However, three-dimensional imaging modalities such as quantitative computed tomography (QCT) and magnetic resonance (MR) imaging offer the ability to separately examine different factors that may play independent and important roles in osteoporosis. These factors include the density of the trabecular and cortical compartments as well as the pattern of trabecular microarchitecture. New developments in QCT include volumetric approaches for precise compartmental assessment of the spine and proximal femur as well as thin-slice tomography of the vertebral body for assessment of trabecular texture. In addition, ultrahigh resolution CT scanners (spatial resolution ë50-150¦) have been developed for imaging of trabecular structure in specimens and in some cases for the peripheral skeleton (distal radius and phalanges). High resolution MR measurements may be employed for assessment of the trabecular texture at a range of peripheral sites, including the calcaneus, distal radius, and phalanges.

A structural parameter for characterizing early trabecular changes in the spine in osteoporosis

The pattern of the spongiosa in lumbar vertebrae demonstrated by ultra high resolution CT was treated statistically. Comparison of normals with osteoporotic vertebrae showed no significant difference in the large dominant trabeculae. However, there is a significant difference when quantifying the fine structures which are not to resolve lying between the larger trabeculae.

Radiology for cochlear implants

One fifth of patients selected for cochlear implants have such bony irregularities in the cochlear duct that full insertion of a multichannel electrode array is impossible. Three cases of cochlear deafness are presented where pre- and post-operative radiology played an important part in the management. Standard CT at 2 mm cuts is compared with ultra high resolution CT at 1 mm cuts. The pitfall of poor definition is that the inexperienced surgeon may find himself unexpectedly drilling out an obliterated cochlear duct. Sections 30 degrees caudal to Reid's infra orbito-meatal base line at 1 mm intervals give maximum information for minimum radiation. Plain films show the placement of individual platinum electrode contacts in relation to the spiral 'frequency map' of the cochlea. This is vital information for the audiologist who has to route specific frequencies to specific sites within the ear for a good hearing result.

Computed tomography of the human developing anterior skull base

The ossification of the anterior skull base, especially the lamina cribrosa, has been studied by computed tomography and histopathology. Sixteen human fetuses, (referred to our laboratory for pathological examination after spontaneous abortion between 18 and 32 weeks of gestation) and three infants, (1, 2 and 6 years of age, respectively) were examined. The cartilaginous preformation of the anterior skull base creates a ‘pseudo-defect’ on CT in the coronal plane, even with ultra thin sections and high resolution CT. By the age of 6 years of life this ‘artefact’ is no longer, as the present ossification of the lamina cribrosa is, by that time, complete.

High-resolution computed tomography of the normal rat nephrogram.

This study describes a unique, film-recorded computed tomography (CT) system and its use in studying contrast flow between anatomic compartments of the rat kidney. The CT apparatus, composed of a microfocal spot tube, rotating animal carrier, film-cassette translator, and control electronics, was used to expose "sinograms" of 3:1 magnification through the kidneys of normal rats prior to and 2, 15, 30, 60, and 120 minutes after intravenous contrast injection. Microdensitometry and computer reconstruction resulted in CT images representing 1-mm thick coronal sections with lateral resolution of 150 micron. With this novel technique of ultrahigh-resolution CT, temporal alterations in absorption coefficient of cortical and medullary nephrographic components were depicted for contrast flow study in our small animal model.