Linear vs. pluridirectional tomography of the chest: correlative radiographic anatomic study

The basic imaging capabilities of 15 degrees linear, 30 degrees linear, hypocycloidal, and trispiral tomographic movements were compared using a fresh frozen human cadaver. Large numbers of tomograms, 100 with each tomographic movement, were compared as a motion study developed by copying the four tomographic series on movie film. In addition, the integrity of the tomograms was compared with radiographs of representative 2 mm coronal sections sawed from the fresh frozen thorax specimen. The study demonstrated the theoretical conclusion that a linear tomogram is not a sectional image and does not truthfully represent the planar anatomy of the intended layer. The pluridirectional tomograms, on the other hand, do accurately depict the anatomic section. The more general use of pluridirectional tomographic techniques in the chest is encouraged and should be used as the basis for comparing conventional tomographic imaging capabilities to other new modalities, particularly computed tomography.     

Adenomyomatosis of the gallbladder in CT

The computed tomographic findings of adenomyomatosis of the gallbladder are described in nine patients, including all main types of this disease. Diagnosis was confirmed by typical cholecystographic findings in all cases, as well as by histological evaluation in three cases. Only in the fundal type were the intramural diverticula well visualized on CT. Although in the other types the Rokitansky-Aschoff sinuses were not clearly shown by CT, when performed without application of a cholegraphic agent, the computed tomographic findings nevertheless appeared to be characteristic. In the area involved, layering of the thickened gallbladder wall, associated with irregular ill-defined borders of the inner layer, appears to be typical. Visualization of these findings was improved following enhancement by intravenous contrast media.     

Intravenous computed tomographic cholangiography in acute cholecystitis. A comparison with conventional cholangiography

Forty-nine patients with clinical signs of acute cholecystitis underwent conventional and computed tomographic cholangiography. Among 39 patients with signs of contrast medium in the biliary system at both examinations there was a diagnostic discrepancy in only one patient. Conventional radiography demonstrated cholecystopathy in this patient while contrast medium in the gallbladder and an acute pancreatitis were found at computed tomography. Ten patients with an indeterminate conventional cholangiography had a conclusive computed tomographic examination. Twenty of 30 patients with an abnormal computed tomographic cholangiography underwent cholecystectomy and all had diseased gallbladders. All 17 patients with histopathologically confirmed acute cholecystitis had signs of subserosal edema and/or changes in the omental fatty tissue adjacent to the gallbladder at computed tomography. A layer of tissue of water-density adjacent to the gallbladder and/or changes in omental fatty tissue were also seen in one patient with congestive heart failure and in one with a penetrating duodenal ulcer. None of the 19 patients with a normal computed tomographic cholangiography had a proven acute cholecystitis.     

Tomoscopy: dynamic layer imaging without mechanical movements

A tomographic system in which electronic movement of the x-ray source and the image receptor replace the mechanical movement of conventional tomography has been constructed and tested. Because the system permits very short, rapidly repeated exposures, viewing by television provides real-time fluoroscopic tomography, termed tomoscopy. Further, electronic adjustment of tomographic layer height permits rapid direct search for the optimum layer. The system requires no more than conventional fluoroscopic radiation levels and resolves 3 line pairs per millimeter (LP/mm) in the televised image and 4 LP/mm in the spot film images. It offers rapid, highly customized, high-resolution tomography under direct fluoroscopic control. Precise percutaneous biopsy with integrated needle-controlled equipment and tomography of contrast-filled blood vessels incorporating digital subtraction principles are theoretic possibilities.     

Radiology of the pleural fissures

The pleural fissures, formed by a double layer of visceral pleura, represent extensions of the pleural space between lobes of the lungs. The fissures are frequently an anatomic barrier to the spread of inflammatory or neoplastic disease. Identification of the fissures is important for the accurate localization of lung parenchymal or pleural pathology. The plain radiographic and computed tomographic (CT) imaging of normal and variant fissural anatomy, as well as of some abnormalities that may affect the fissures will be reviewed and illustrated.     

Quantity of tomographic blurring.

A spiral tomographic movement gives rise to a lower quantity of blurring than does a circular movement with the same tomographic angle since in the former the focus comes nearer to the central point. It has been demonstrated that the transfer function may be used to express the quantity of blurring for different tomographic movements. For the sake of convenience the blurring quantity for every type of spiral movement may be expressed in terms of the tomographic angle of a circular movement giving rise to the same transfer function.     

Transtomography: a new tomographic scanning technique

OBJECTIVES: To introduce and test a new tomographic technique, namely transtomography, making it possible to expose tomographic images employing the narrow beam of an advanced panoramic machine. METHODS: The working principle of the new technique is described. It combines a translational movement with a pendular movement of the beam that creates motion unsharpness analogous to that of conventional tomography. In order to verify whether the new technique works and results in tomographic images, test radiographs were exposed on phantoms. RESULTS: The principle of transtomography works and give images with properties essentially equivalent to those of conventional tomography. With the transtomographic technique using a narrow beam, tomographic images may be exposed with an advanced panoramic machine. CONCLUSION: Transtomography may be employed to expose tomographic images basically on the same indications as for conventional tomography.     

A feasibility study on gamma-ray tomography by Monte Carlo simulation for development of portable tomographic system

The electron beam X-ray tomographic scanner has been used in industrial and medical field since it was developed two decades ago. However, X-ray electron beam tomography has remained as indoor equipment because of its bulky hardware of X-ray generation devices. By replacing X-ray devices of electron beam CT with a gamma-ray source, a tomographic system can be a portable device. This paper introduces analysis and simulation results on industrial gamma-ray tomographic system with scanning geometry similar to electron beam CT. The gamma-ray tomographic system is introduced through the geometrical layout and analysis on non-uniformly distributed problem. The proposed system adopts clamp-on type device to actualize portable industrial system. MCNPx is used to generate virtual experimental data. Pulse height spectra from F8 tally of MCNPx are obtained for single channel counting data of photo-peak and gross counting. Photo-peak and gross counting data are reconstructed for the cross-sectional image of simulation phantoms by ART, Total Variation algorithm and ML-EM. Image reconstruction results from Monte Carlo simulation show that the proposed tomographic system can provide the image solution for industrial objects. Those results provide the preliminary data for the tomographic scanner, which will be developed in future work.     

CT appearance of the normal inferior pulmonary ligament

The inferior pulmonary ligament, a double layer of pleura that tethers the lower lobe of the lung to the mediastinum, is rarely appreciated on plain radiographs but may be involved in pathologic processes. A linear structure on axial computed tomographic (CT) images of the lung bases corresponds to the inferior pulmonary ligament on cadaver sections. Review of 100 CT studies identified at least one inferior pulmonary ligament in 42%. Its presence and configuration did not correlate with patient age or gender. The anatomy and CT appearance of the ligament are discussed.     

Length-based Fourier analysis in the pre-excitation syndrome

Length-based Fourier analysis (LFA) was applied to tomographic gated blood-pool study, and phase and percent-shortening diagrams were generated. In 22 patients with pre-excitation syndrome and ten control subjects, the most basal short-axis section was used for tomographic analysis. When the initial abnormal phase was considered as the location of accessory conduction pathway (ACP), correct diagnosis for the localization of ACP was given in 19 of 22 patients. In ten control subjects, no specific segments of initial phase were noted, although six patients had initial phase in the septal or paraseptal segments. The tomographic LFA was more effective for pinpointing the segment of the earliest phase than tomographic count-based phase analysis. The LFA provided objective three-dimensional information for contraction sequence. Because movements of ventricular edges are essential in tomography, the LFA was considered to be a reasonable approach for the analysis of tomographic gated blood-pool study.     

Tomographic DSA using temporal filtration: initial neurovascular application

A preliminary study showed that encouraging laboratory results reported previously using tomographic digital subtraction angiography (DSA) can be transferred to clinical application for neurovascular imaging. Tomography may show cervical carotid disease more clearly than standard DSA images, and it eliminates the interference caused by overlapping vessels. Production of multiple tomographic image planes from a single set of projection data, tomosynthesis, must be incorporated into this imaging system before tomographic DSA becomes clinically useful. This is a practical reality with the present equipment; clinical evaluation of this new capability is underway.     

I-123 HIPDM brain imaging with a rotating gamma camera and slant-hole collimator

The performance of a slant-hole collimator was compared with that of a standard straight-bore, low-energy collimator for tomographic imaging of I-123-iodinated amine brain agents. Improved in-slice resolution was due to the greater proximity between collimator and the subjects' heads. We conclude that high quality tomographic images of the brain can be obtained from rotating cameras equipped with slant-hole collimators.     

Optimised tomography for clinical use

A technique elaborated by the present authors (1974) for the establishment of optimum tomographic movements was applied to ear tomography in order to design a movement that is not too complex, but yielding good tomographic depiction. Such a movement was found to consist of a spiral of 5 revolutions. Modern engineering appears to allow such complex movements to be carried out with satisfactory stability within a reasonable exposure time.     

Absorbed doses on patients undergoing tomographic exams for pre-surgery planning of dental implants

The thermoluminescent (TL) dosimetry was used to measure entrance skin absorbed doses at anatomical points close to critical organs of patients undergoing tomographic techniques as part of a pre-surgery planning for dental implants. The dosimetric procedure was applied in 19 patients, and absorbed doses could be measured with a combined uncertainty down to 14%. Results showed that patient doses may be increased by a factor of 20 in the helical computed tomography compared to panoramic and spiral conventional tomographic exams.     

Orbital trauma evaluation by computed tomography

Computed tomographic scans are useful for the evaluation of orbital trauma because they provide visualization of fractures, soft tissue damage, and embedded foreign bodies. Six cases are presented to demonstrate the usefulness of these studies in the evaluation of patients with a variety of injuries. By using both coronal and axial computed tomographic scans, orbital details can be studied with three-dimensional accuracy.     

Technical note. Computer assisted analysis of tomographic images of the brain

A computer system for the analysis of computed tomography and positron emission tomography scans of the brain is described. The system, called TOAP (Tomographic Overlay and Analysis Program), permits the registration of user specified slices from a digital brain atlas with the tomographic images. Regions of interest can then be defined with respect to the atlas. The system thus affords an objective and reproducible means for the analysis of tomographic images.     

SPECT性能的定量质量控制的新进展

目的：单光子发射计算讥断层仪（SPECT）的完整性性能测试项目，过去发表和使用的步骤很复杂．化费时间很长，并需要特殊的测试条件．美国核医学委员会最近推荐了简单、实用、需少量测试仪器的方法，几小时内就能用常用的核医学仪器完成，它能够测出均匀度和灵敏度．旋转的稳定性，断层的空间分辨率均匀度和对比度，并可进行准确的衰减校正，此步骤在3小时内即可全部完成、仅需要^57Co泛源、线源和断层圆柱形模型．此方法对仪器的购买验收及仪器的常规检测有实用价值。     

Tomographic levels for intravenous urography: CT-determined guidelines

The selection of levels for tomographic sections of the kidneys during intravenous urography has previously been based on empirical observation. Three hundred abdominal computed tomographic scans were analyzed for the anteroposterior (AP) midpoints of the kidneys and their relationship to the patient's AP abdominal diameter. A graph for selection of tomographic levels was generated and compared with existing methods. These guidelines enable a more objective approach to urographic tomography.     

Gated cardiac tomography

An ECG gated tomographic system is described and its application to routine diagnosis of cardiac wall dyskinesis discussed. The tomographic sections are gathered by a single section scanning system (Aberdeen Section Scanner). Technetium labelled red blood cells are used as the imaging agent. The time of the occurrence of the ECG R-wave is superimposed on the tomographic projection data stream and the gated images produced subsequently. The average patient study requires 15 min. Images at 8 phases of the cardiac cycle are generated at each of 5 levels, 16 mm apart, covering the length of the left ventricle. The images are stored as a three dimensional matrix and may be analysed in sections at any orientation. Fourier analysis of computer generated short axis sections are used to generate a set of coefficients describing the contraction of the left ventricle. The coefficients for each patient study are displayed as a series of two dimensional polar images, schematically displaying the spatial distribution of the coefficient over the left ventricle. These polar images are further analysed by comparison with distributions obtained from normal patient studies. The calculated deviations from the normal are then used to diagnose the magnitude and position of any dyskinesis. Initial results show that the tomographic system is capable of routinely detecting inferior cardiac wall dyskinesis, showing an advantage over non tomographic techniques.     

Gated cardiac tomography

An ECG gated tomographic system is described and its application to routine diagnosis of cardiac wall dyskinesis discussed. The tomographic sections are gathered by a single section scanning system (Aberdeen Section Scanner). Technetium labelled red blood cells are used as the imaging agent. The time of the occurrence of the ECG R-wave is superimposed on the tomographic projection data stream and the gated images produced subsequently. The average patient study requires 15 min. Images at 8 phases of the cardiac cycle are generated at each of 5 levels, 16 mm apart, covering the length of the left ventricle. The images are stored as a three dimensional matrix and may be analysed in sections at any orientation. Fourier analysis of computer generated short axis sections are used to generate a set of coefficients describing the contraction of the left ventricle. The coefficients for each patient study are displayed as a series of two dimensional polar images, schematically displaying the spatial distribution of the coefficient over the left ventricle. These polar images are further analysed by comparison with distributions obtained from normal patient studies. The calculated deviations from the normal are then used to diagnose the magnitude and position of any dyskinesis. Initial results show that the tomographic system is capable of routinely detecting inferior cardiac wall dyskinesis, showing an advantage over non tomographic techniques.