Biomedical subjects

M E Noz

Publications and source records attributed to M E Noz.

13 recordsLinked to original sources

PubMed1992

High-attenuation lymphadenopathy in AIDS patients: significance of findings at CT.

A retrospective evaluation was performed of the location and attenuation characteristics of abdominal and pelvic lymphadenopathy, identified at dynamic sequential bolus computed tomography (CT) in 69 patients with acquired immunodeficiency syndrome (AIDS). Lymph node appearance at CT was characterized as hyperattenuating, isoattenuating, or hypoattenuating relative to the iliopsoas muscle. The significance of finding hyperattenuating adenopathy in the patient population was evaluated. Thirty-three patients had hyperattenuating adenopathy, including 26 with the epidemic form of Kaposi sarcoma (KS). Of 38 patients with epidemic KS, 26 had hyperattenuating, 11 had isoattenuating, and one had hypoattenuating lymphadenopathy. The positive predictive value of hyperattenuating adenopathy for epidemic KS was 79%. These findings were statistically significant at the 95% confidence interval (P < .005). Hyperattenuating lymphadenopathy, identified on dynamic sequential bolus CT scans in AIDS patients, was seen with disseminated KS in approximately 80% of cases.

AIDS-Related Opportunistic Infections↗

PubMed1991

CT-SPECT fusion for analysis of radiolabeled antibodies: applications in gastrointestinal and lung carcinoma.

Fusing or image registration improves the information obtained by correlating images from various imaging modalities. We "fused" radiolabeled antibody SPECT with CT in patients with colorectal or lung cancer. We identified corresponding landmarks on cross-sectional images and used standard graphics algorithms for untilting to match planes of reconstruction and for two-dimensional warping or transformation of images or regions of interest. Fusing localizes activity on SPECT to specific anatomic structures and decreases SPECT false positives and CT false negatives.

Antibodies, Monoclonal↗

PubMed1991

Bowel obstruction: evaluation with CT.

Eighty-four computed tomographic (CT) scans from patients referred for bowel obstruction between January 2, 1988, and December 31, 1989, were retrospectively evaluated. A pair of radiologists without knowledge of patient histories determined the presence or absence of bowel obstruction. Sixty-four patients ultimately proved to have intestinal obstruction, and 20 did not. Diagnosis was established by means of surgery (n = 39), barium studies (n = 17), and clinical course (n = 28). Causes of obstruction included adhesions (n = 37), metastases (n = 6), primary tumor (n = 7), Crohn disease (n = 4), hernia (n = 3), hematoma (n = 2), colonic diverticulitis (n = 2), and other (n = 3). In addition, 83 CT examinations in patients with no history or indication of intestinal obstruction were simultaneously reviewed. The overall sensitivity was 94%, specificity was 96%, and accuracy was 95%. The cause of obstruction was correctly predicted in 47 of 64 cases (73%). Intestinal obstruction was not diagnosed in any of the 83 control patients. CT is most useful in patients with a history of abdominal malignancy and in patients who have not been operated on and who have signs of infection, bowel infarction, or a palpable abdominal mass.

Barium Sulfate↗

PubMed1991

Hepatic hemangiomas: diagnosis with fusion of MR, CT, and Tc-99m-labeled red blood cell SPECT images.

A method of image analysis was developed for correlation of hemangiomas detected at computed tomography (CT) and/or magnetic resonance (MR) imaging with increased blood pool activity evident at single photon emission CT (SPECT) performed after labeling of red blood cells with technetium-99m. Image analysis was performed in 20 patients with 35 known hepatic hemangiomas. After section thickness and pixel sizes of the different studies were matched, intrinsic landmarks were chosen to identify anatomically corresponding locations. Regions of interest (ROIs) drawn on the CT and/or MR images were translated, rotated, and reprojected to match the areas of interest on the corresponding SPECT images by means of a two-dimensional polynomial-based warping algorithm. Analysis of ROIs on 30 SPECT-MR and 20 SPECT-CT pairs of registered images provided absolute confirmation that 34 suspected hemangiomas identified on SPECT images correlated exactly with lesions seen on CT and/or MR images. Accuracy of fusion was within an average of 1.5 pixels +/- 0.8 (+/- 1 standard deviation). The technique enabled diagnostic confirmation of hemangiomas as small as 1.0 cm and proved useful for evaluating lesions located adjacent to intrahepatic vessels.

Adult↗

PubMed1990

Definitive diagnosis of hepatic hemangiomas: MR imaging versus Tc-99m-labeled red blood cell SPECT.

Thirty-seven patients with 69 suspected hemangiomas found by means of computed tomography (CT) and/or ultrasound were studied with both 0.5-T magnetic resonance (MR) imaging and single photon emission CT (SPECT) with technetium-99m-labeled red blood cells. Using a criterion of "perfusion-blood pool mismatch," SPECT readers diagnosed 50 of 64 hemangiomas and all five "nonhemangiomas" (sensitivity, 78% [95% confidence interval, 0.664 - 0.864]; accuracy, 80% [0.69 - 0.877]). Qualitative analysis of lesion signal intensity on T2-weighted spin-echo MR images allowed readers to diagnose 58 of 64 hemangiomas and four of five nonhemangiomas (sensitivity, 91% [0.814 - 0.96]; accuracy, 90% [0.807 - 0.951]). Because of the significantly higher cost of MR imaging and its inability to categorically differentiate hemangiomas from hypervascular metastases, the authors consider SPECT to be the method of choice for diagnosing hepatic hemangiomas. MR imaging should be reserved for the diagnosis of lesions smaller than 2.0 cm and for those 2.5 cm and smaller adjacent to the heart or major hepatic vessels; in such cases MR imaging was found superior to SPECT.

Adult↗

PubMed1989

CT-SPECT fusion to correlate radiolabeled monoclonal antibody uptake with abdominal CT findings.

To enhance the information provided by computed tomography (CT) and single photon emission computed tomography (SPECT) performed with radiolabeled, anti-carcinoembryonic antigen monoclonal antibody (MoAb), the authors performed fusion of these types of images from eight subjects with suspected colorectal adenocarcinoma. Section thickness and pixel size of the two studies were matched, coordinates of corresponding points from each study were identified, and CT sections were translated, rotated, and reprojected to match the corresponding SPECT scans. The CT-SPECT fusion enabled identification of anatomic sites of tumor-specific MoAb accumulation in four cases, showed non-specific MoAb accumulation in two, and helped confirm information only suggested by the two studies separately in one.

Adenocarcinoma↗

PubMed1988

Multimodality image display: desirable frame buffer characteristics.

The intent of this paper is to understand the characteristics of those frame buffers currently used to display images, versus more ideal frame buffers for medical image display purposes. This study is based on current needs and what characteristics might be desirable. Two case examples are presented: (1) a system developed for high quality computer graphics and (2) a system developed for nuclear medicine and radiation therapy treatment planning. Our study considers: (1) defining a pixel depth sufficient to hold data, (2) the desirability of multiple color look-up tables, (3) how cine loops are managed, and (4) display memory size.

Computer Graphics↗

PubMed1987

Use of graphical techniques for error evaluation.

Anatomic localization in functional (such as PET) imaging often requires a structural (such as CT or NMRI) study of the brain in the same plane. Some neuropsychiatric conditions make it difficult for a patient to hold his/her head immobile even when a rigid head holder is used. We studied the effect of tilt of the anatomic reference image, in this instance CT, relative to the functional image, here PET, on the quantification of receptor ligand concentration in anatomically defined regions of the brain.

Computer Graphics↗

PubMed1986

Standardizing the raster display for medical images using a fixed set of frame buffer primitives.

Two major difficulties associated with medical image processing are the diverse image formats that must be dealt with because of the differences in image sources and the number of incompatible display systems available for viewing images both before and after processing. We describe a very small set of primitives that need to be defined to utilize any raster display. When these primitives have been implemented for a particular device, then a standard set of image display programs can be compiled and images and the results of image processing can be displayed. The main purpose of this paper is to describe what a raster display looks like from the point of view of the programmer and to define the specific hardware and software data about the raster display that must be known in order to implement the small set of primitives.

Computer Graphics↗

PubMed1986

Local area networks in an imaging environment.

There is great interest at present in incorporating image-management systems popularly referred to as picture archiving and communication systems (PACS) into imaging departments. This paper will describe various aspects of local area networks (LANs) for medical images and will give a definition of terms and classification of devices by describing a possible system which links various digital image sources through a high-speed data link and a common image format, allows for viewing and processing of all images produced within the complex, and eliminates the transport of films. The status of standards governing LAN and particularly PACS systems along with a proposed image exchange format will be given. Prototype systems, particularly a system for nuclear medicine images, will be presented, as well as the prospects for the immediate future in terms of installations started and commercial products available. A survey of the many questions that arise in the development of a PACS for medical images and also a survey of the presently suggested/adopted answers will be given.

Archives↗

PubMed1977

A modular computer system for the nuclear medicine/ultrasound laboratory.

Computer-controlled graphic displays are a necessity in many nuclear medicine studies. The authors propose using a set-up consisting of three modules: (a) a display system based on television technology; (b) an instrument interface employing list mode and having a low information loss rate; and (c) flexible modular software which can easily be tailored to the needs of both radiologists and technicians. The authors consider a mini-computer system with broad, flexible applications to be a valuable tool, particularly for those function studies which can only be done by means of nuclear medicine techniques.

Computers↗

PubMedDate not supplied

QSH: a minimal but highly portable image display and handling toolkit.

We describe a software system developed to handle images obtained from different sources, namely, computer-assisted tomography, positron emission tomography, single photon emission tomography and magnetic resonance imaging. In developing the system, it was necessary to address the following points. (1) The types of values that were encountered in both the header information and the pixel elements, namely, integers, floating point numbers, complex numbers and strings. (2) The use of domain-dependent sets of keys, that is, how to choose keys and how to stabilize the use of keys among the user population. This is, for example, how information such as the patient name, or the activity in becquerel is kept. It is necessary to keep both the key values and the units. (3) The development of a method for providing a database using flat files, i.e. linear text. (4) The maintenance of a history of values and operations. This is necessary in order to address the problem of determining from an image how that image was produced. The connection between an image and how it was derived is analogous to describing how a secondary standard is derived from a primary one.

Algorithms↗

PubMedDate not supplied

Image formats: five years after the AAPM standard for digital image interchange.

The publication of AAPM Report No. 10 was the first attempt to standardize image formats in the medical imaging community. Since then, three other groups have formed (CART--the Scandinavian collaboration for Computer Assisted Radiation Therapy treatment planning; ACR-NEMA, a collaboration whose purpose is to formulate a standard digital interface to medical imaging equipment; and COST B2 Nuclear Medicine Project a European collaboration whose purpose is to define a format for digital image exchange in Nuclear Medicine). The AAPM format uses key-value pairs in plain text to keep track of all information associated with a particular image. The radiation oncology community in the U.S. has been defining key-value pairs for use with CT, nuclear medicine and magnetic resonance (MR) images. The COST B2 Nuclear Medicine Project has also adopted this format and together with the Australian/New Zealand Society of Nuclear Medicine Technical Standards Sub-Committee which has also adopted this format, has defined an initial set of key-value pairs for Nuclear Medicine images. Additionally, both ACR-NEMA and CART have been defining fields for use with the same types of images. The CART collaboration has introduced a database which is available electronically, but is maintained by a group of individuals. ACR-NEMA operates through committee meetings. The COST B2 Nuclear Medicine Project operates through electronic (and postal where necessary) mail. To insure a consistent set of field names in such a rapidly developing arena requires the use of a server rather than a committee. Via a server a person would inquire if a particular field had been defined. If so, the defined name would be returned.(ABSTRACT TRUNCATED AT 250 WORDS)

Health Physics↗