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At least 37 records · Page 2Linked to original sources
PubMed2026

Non-invasive screening in hereditary cancer: a randomized controlled trial to test cell-free DNA-based early detection in the CHARM consortium.

Individuals with hereditary cancer syndromes are born with germline genetic variants that significantly increase their lifetime risk of developing multiple cancers. Cancer rates and overall mortality can be reduced with intensive surveillance to facilitate early cancer detection. However, participating in diagnostic imaging and endoscopy surveillance programs is often time-consuming, overwhelming, inconvenient, and anxiety-inducing. To improve this, multi-cancer early detection tests are being developed using cell-free DNA (cfDNA) sequencing analysis to detect cancers with more sensitivity than conventional screening methods. Our community (the CHARM consortium: Cell-free DNA in Hereditary And high-Risk Malignancies) has been exploring the use of cfDNA sequencing in hereditary cancer, and has launched the CHARM2 prospective randomized controlled trial, which is enrolling 1000 participants with Hereditary Breast and Ovarian Cancer, Lynch syndrome, Li-Fraumeni syndrome, Neurofibromatosis type 1 and Hereditary Diffuse Gastric Cancer to improve equitable access, early detection and surveillance for high-risk individuals. All participants will have screening as per conventional syndrome-specific surveillance recommendations. Half the participants (experimental cohort) will also have cfDNA analysis at least three times a year, with abnormal results triggering dedicated clinical imaging and diagnostic evaluation, and heightened surveillance. Vetted by our patient advisors, validated patient-reported outcome and experience measures assessing participant psychosocial outcomes, engagement, and test preferences will be administered to both arms. Our goal is to inform if and how cfDNA analysis could be implemented into routine clinical care and offer a path to equitable and more convenient cancer screening for all high-risk Canadians.

Female↗
PubMed1978

The effect of image quality on the identification of cephalometric landmarks.

The effect of rare-earth phosphor intensifying screens on diagnostic image quality was examined. Five observers were asked to identify ten landmarks on each of fifteen cephalometric images having varying screen-film-kvp combinations. The most sensitive screens were found to significantly affect diagnostic image quality and thereby the reliability of landmarks identification. This finding was, however, only established for those landmarks having the lowest standard deviations and the clinical significance is thus questionable. There would appear to be other more important factors than physical image quality involved in the reliability of landmark identification. High intensifying screens are, therefore, recommended for use in cephalometric analyses since they help to reduce patient dose and do not appear to sacrifice diagnostic image quality to the extent that the reliability of cephalometric measurements is significantly affected.

Cephalometry↗
PubMed1979

Images, image quality and observer performance: new horizons in radiology lecture.

Technical and diagnostic image quality are distinguished and the limitations of three methods currently used for assessing diagnostic image quality are discussed. They are evaluations based on individual clinical experience, measurement of diagnostic performance, and physical measurements made on images or imaging systems. Finally, a psychophysical approach to image quality evaluation is presented and its potential value discussed.

Humans↗
PubMed1977

The role of Ga-67 citrate imaging and diagnostic ultrasound in patients with suspected abdominal abscesses.

Fifty patients with suspected abdominal abscesses were examined by [67Ga[ Gallium citrate imaging and abdominal sonography. Fifteen of the patients had a proven intra-abdominal abscess; Gallium-67 images were positive in 13 (87%), while the sonogram detected the abscess in 11 (73%). Nineteen patients had true-negative radionuclide images and sonography, and one had a false-positive result by both procedures. The remaining 15 patients did not have abdominal abscesses, but did have other abnormalities (e.g., pyelonephritis, extra-abdominal sites of inflammation) which were detected by the nuclide study. Gallium-67 imaging and abdominal ultrasound have similar sensitivity for detection of abdominal abscesses. A significant advantage of Gallium imaging is its ability to detect other inflammatory foci (both within and outside the abdomen).

Abdomen↗
PubMed1976

New methods of imaging in diagnostic radiology Sylvanus Thompson Memorial Lecture.

A brief history of the recent developments in computer-assisted tomography (CAT) is presented. The development of whole-body scanners from the basic brain scanner, the trend towards higher-speed scanners using multiple detectors in a fan-type geometry, and some of the unsolved problems related to CAT scanners are discussed, as well as the potential use of whole-body scanning in radiotherapy treatment planning and in radiobiology. A review of recent developments in electrostatic imaging is presented and a new method of imaging called ionography is described in detail. It is shown how a single exposure can be used to produce a number of copies, each with a different amount of edge contrast, under the control of the radiologist. Further, it is shown how this can be done using a closed system so that the ionography chamber never needs to be opened. Some of the recent commercial developments in this field are described. It is suggested that in the future radiology departments may be replaced by departments of imaging, which will include all ways of obtaining diagnostic information and where such a department would be problem oriented rather than technique oriented. The need for basic scientific support by a medical physics and engineering group in such a department is emphasized.

Electrons↗
PubMed1979

Multiple imaging modalities for the study of pancreatic disease.

Gray scale ultrasonography (US) and computed tomography (CT) have enhanced the role of various imaging modalities in the evaluation of patients with suspected pancreatic disease. When these anatomical studies are normal or equivocal, a functional, radionuclide pancreas scan may be useful. Pancreatic imaging can be achieved using ultrasound, transmission CT, single photon radionuclide imaging, and positron emission CT. A diagnostic imaging decision chart for the evaluation of patients with possible pancreatic disease is useful in choosing the correct imaging modality in a specific situation. Such a chart and its theoretic basis are described in this review. The need to optimize the pancreatic work-up with respect to cost-benefit decisions and diagnostic accuracy, sensitivity, and specificity are of particular concern to the physician. Of all the potential areas for disease, the pancreas has been and remains a particularly difficult diagnostic problem.

Humans↗
PubMedDate not supplied

Dose reduction in mammography.

Two mammographic imaging systems (Xerox and Kodak Min-R) were evaluated. Three hundred consecutive mammographic examinations were performed utilizing both imaging systems. Results of these studies indicated equivalency of image detail at identical source-to-image receptor distance (SID). Patient exposure as measured by the thermoluminescent dose meter for Kodak Min-R system was approximately 25% that of Xeromammography system. Due to reduced power requirement, it is possible to increase the SID when Min-R system is employed for imaging. Improved geometric arrangement provided superior diagnostic images in 5.5% of 200 comparison cases.

Female↗
PubMed1979

Bone scanning in otolaryngology.

Modern radionuclide bone scanning has introduced a new concept in physiologic and anatomic diagnostic imaging to general medicine. As otolaryngologists must diagnose and treat disease in relation to the bony and/or cartilaginous supporting structures of the neurocranium and upper airway, this modality should be included in the otolaryngologist's diagnostic armamentarium. It is the purpose of this manuscript to study the specific applications of bone scanning to our specialty at this time, based on clinical experience over the past three years. This thesis describes the development of bone scanning in general (history of nuclear medicine and nuclear physics; history of bone scanning in particular). General concepts in nuclear medicine are then presented; these include a discussion of nuclear semantics, principles of radioactive emmissions, the properties 99mTc as a radionuclide, and the tracer principle. On the basis of these general concepts, specific concepts in bone scanning are then brought forth. The physiology of bone and the action of the bone scan agents is presented. Further discussion considers the availability and production of the bone scan agent, patient factors, the gamma camera, the triphasic bone scan and the ultimate diagnostic principle of the bone scan. Clinical applications of bone scanning in otolaryngology are then presented in three sections. Proven areas of application include the evaluation of malignant tumors of the head and neck, the diagnosis of temporomandibular joint disorders, the diagnosis of facial fractures, the evaluation of osteomyelitis, nuclear medicine imaging of the larynx, and the assessment of systemic disease. Areas of adjunctive or supplementary value are also noted, such as diagnostic imaging of meningioma. Finally, areas of marginal value in the application of bone scanning are described.

Bone and Bones↗
PubMed1979

Early imaging of experimental intestinal infarction with 99mTc-pyrophosphate.

Extensive mucosal small-bowel infarction was produced in 8 dogs by occluding the cranial mesenteric artery. After one hour of reperfusion, 15 mCi (555 MBq) of 99mTc-pyrophosphate was intra-arterially injected into 4 dogs and venously into the other 4. Positive images were obtained in all dogs except 1 which had received an intravenous injection. Diagnostic images were obtained consistently as early as 15 minutes after injection, and the infarcted bowel could still be visualized two hours later. The average tracer content in infarcted small bowel was 0.015% I.D./g. This was about eight times the uptake found in normal dogs. The results show that experimental small-bowel infarction can be detected as early as five hours after the onset of ischemia.

Animals↗
PubMed1977

Clinical information from medical images. A comparison of two types of ultrasonic image in the detection of focal intrahepatic lesions.

If the uncertainty in the diagnosis is measured before and after viewing a diagnostic image, the change in uncertainty is a measure of the information contributed by that image. The formal basis of information theory has been used to calculate the change in uncertainty. These analytical methods have been applied to assess two types of ultrasonic grey-scale image in the demonstration of possible focal intrahepatic lesions.

Humans↗
PubMed1979

Formulation and evaluation of ethiodized oil emulsion for intravenous hepatography.

A study was conducted to prepare and evaluate an ethiodized oil emulsion for intravenous administration that would selectively opacify the liver. Several formulations with differing globule size were prepared and compared for their in vivo activity (degree of liver opacification obtained) and stability. Results of studies conducted in rabbits and monkeys revealed that the oil globules that concentrate most in liver were 2.0--3.0 micrometer in diameter. The formulation of choice was stable for 6 months at refrigeration temperature (2--6 degree). In monkeys, this formulation produced an improved diagnostic image of the liver using computerized tomography at a dose of 0.2 ml/kg. The potential use of such emulsions in diagnostic radiology is briefly discussed.

Animals↗
PubMed1979

Iatrogenic alterations in radionuclide biodistributions.

The biodistribution of radiotracers used in diagnostic imaging is grossly and recognizably altered by a wide variety of drugs and other treatment modalities, such as surgery and radiotherapy. Knowledge of such altered biodistribution is important both in making diagnostic inferences from scans and in dosimetric considerations.

Anesthetics↗
PubMed2026

Shielding performance and clinical applicability of lead-free materials in computed tomography.

Owing to the high radiation exposure associated with computed tomography (CT) examinations and the image quality degradation caused by conventional radiation shielding materials, this study evaluated the dose reduction performance and image quality maintenance potential of a newly developed lead-free composite shielding material. This material was composed of bismuth, tungsten, tungsten carbide, aluminium, and polyurethane. Phantom-based dose measurements demonstrated that the shielding material achieved dose reduction rates ranging from 17.6% to 37.6%, depending on tube voltage. Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and changes in tube current-time product (mAs) under a scout-based automatic exposure control (AEC) protocol were analysed according to the presence or absence of the shielding material across regions. For the clinical evaluation, CT scans were performed on four patients. Furthermore, the images were reviewed to evaluate whether this material affected image quality. The shielding material exhibited radiation reduction levels comparable to those reported in previous studies. SNR and CNR analyses showed minor statistical variations in certain regions; however, most differences were not statistically significant, and even significant differences remained within a range that did not compromise diagnostic image quality. Under the scout-based AEC protocol, the use of the shielding material resulted in less than 1% variation in mAs values. No visually perceptible artefacts or clinically significant image quality degradation were observed. The proposed composite shielding material demonstrated the potential to mitigate some limitations of conventional shielding materials and showed preliminary clinical feasibility as an adjunctive strategy for radiation dose reduction in CT examinations.

Radiation Protection↗
PubMed1978

Effect of screen/film combinations on diagnostic certainty: Hi-Plus/RPL versus Lanex/Ortho G in excretory urography.

A method using radiologists' subjective judgments was developed to compare the quality of the diagnostic image information from two different screen/film combinations (Hi Plus/RPL versus Lanex/Ortho G). A sample of 148 comparison film pairs was obtained in the course of performing 74 urograms using the two film/screen combinations. Each film pair was evaluated by three radiologists, using a blind film-reading format, in regard to:(1) anatomic diagnostic criteria visualization; (2) radiologic diagnostic certainty; (3) presence or absence of quantum mottle; and (4) prediction of which film of a pair was the rare earth screen/film combination. There was a significant difference favoring Hi Plus/RPL in perceived quality of visualization of anatomic criteria. However, the difference was more of statistical rather than practical importance. Diagnostic certainty differed only marginally and slightly favored the Hi Plus/RPL combination. No signficant differences in perception of quantum mottle were attributable to either screen/film combination. Radiologists were able to correctly identify the screen/film combination a significant proportion of the time. Radiation exposure with the Lanex/Ortho G combination was about half that with the Hi Plus/RPL combination. In this study, this would seem to constitute the major factor in film/screen selection.

Adult↗
PubMedDate not supplied

Diagnostic evaluation of the pelvic and abdominal lymphatic system.

Evaluation of the pelvic and abdominal lymphatic systems is the subject of renewed interest by radiologists, radiotherapists, surgeons and medical oncologists. The primary reason for this interest has been the rapid advance of diagnostic imaging technology, particulary in ultrasonography and computerized tomography (CT). Another reason is the realization that with some neoplasms, particularly gynecologic neoplasms, there has been little progress in long-term survival in spite of aggressive local management. A possible explanation for this is "understaging" of neoplasms by previous radiologic procedures. Although lymphangiography has a proved and well-defined place in the diagnostic regimen, it remains tedious, time-consuming and invasive. Gray-scale ultrasound and CT have been widely used for several years and their role, limitations and relationship to lymphangiography have become established. The purpose of this monograph is to provide a short review of the lymphatic system and lymphangiogram, with particular attention to the recent radiologic literature. The role and limitations of the various diagnostic modalities are discussed and the lymphatic drainage and common pelvic neoplasms (as approached in the recent literature) are reviewed. No attempt has been made to define the lymphatic drainage of abdominal visceral organs.

Female↗