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Biomedical subjects

B D Doust

Publications and source records attributed to B D Doust.

At least 37 records · Page 2Linked to original sources
PubMed1984

Frequency domain processing for ultrasonic attenuation measurement in liver.

A frequency domain signal processing scheme is developed for measuring attenuation and attenuation slope in vivo, using equally spaced depth samples and linear regression techniques. The algorithm may be expressed in terms of linear, commuting operators acting on an array of log power spectra. By interchanging operators, a computationally efficient scheme may be developed, and the accuracy of the result assessed in terms of tissue uniformity and frequency linearity. Corresponding algorithms are demonstrated for measurement of attenuation at particular frequencies and attenuation in focal lesions. Measurements have been made using an Octoson water-delay echoscope on both normal and pathological livers. Variation of attenuation with a number of disease states has been found.

Colonic Neoplasms↗
PubMed1981

CT scanning of the breast using a conventional CT scanner.

Using a conventional body CT scanner, computed tomography of the breast was performed on 32 patients known to have or suspected of having breast masses. Xeromammograms were available for comparison in all cases. All mass lesions were histologically proved. Seven patients were examined prone, 25 supine. The prone position yielded pictures that resembled craniocaudal mammograms. Breast asymmetry, skin thickening, stranding from a mass to the chest wall, calcification, and axillary lymphadenopathy could be demonstrated by means of CT. The portion of the breast adjacent to the chest wall was more readily examined by means of CT than by conventional mammography. Internal mammary nodes could not be demonstrated.

Adenofibroma↗
PubMed1980

CT imaging of the thoracic spinal cord without intrathecal contrast medium.

Demonstration of the thoracic spinal cord by computed tomography (CT) without intrathecal contrast medium has not been reported frequently. We studied the factors that affect the demonstration of the thoracic spinal cord by CT. Slice thickness, artifacts, the size of the subarachnoid space, and dose were the most important factors. With optimal factors, CT demonstrates the thoracic cord effectively without intrathecal contrast enhancement.

Contrast Media↗
PubMed1980

Cine display of numerous static ultrasound images: a step toward automation of ultrasound studies.

Ultrasound images were assembled and viewed in a motion picture format to facilitate the laborious task of reviewing numerous sonograms. Sequential, closely spaced images from an automated water bath ultrasound scanner were recorded both on a video disc recorder capable of high speed playback and on a film strip using a 35-mm half frame camera. A conventional 35-mm cine viewer was used to evaluate the film strip. Advantages of the motion picture format are (a) many images can be reviewed easily and rapidly, (b) objects that extend through several images are easily perceived and an impression of the third dimension is obtained, (c) the chances of diagnostic errors due to wide spacing or selective recording of images are lessened, and (d) fuller advantage can be taken of the scanner's capacity for automatic operation. Disadvantages of the technique are (a) respiratory motion must be minimized, and (b) the method is useful only in conjunction with water bath scanners.

Automation↗
PubMed1978

Ultrasonography of abdominal fluid collections.

Ultrasonic examination of abdominal fluid collections sometimes allows identification of the nature of the contained fluid. Abscesses, hematomas, and lymphoceles tend to be ellipsoidal unless confined by particularly resistant structures. Abscesses often contain fine debris. Hematomas develop coarse clumps of strongly echoing material as they age. Lymphoceles have sharp walls and are echo-free. Ascites has an irregular outline, a sharply defined wall, and is echo-free. There may be bowel loops floating in it. Pseudocysts have a widely variable appearance. Bowel loopes that are distended with fluid often show peristalsis. Ultrasonically directed fine needle puncture allows confirmation of the nature of the fluid.

Abdomen↗
PubMed1978

Confusing appearance of a dilated jejunal loop.

A case report is presented concerning a patient with a dilated loop of bowel that was misinterpreted on ultrasound examination. Attention is called to this entity as part of the differential diagnosis of an intra-abdominal fluid collection demonstrated by ultrasound.

Adult↗
PubMed1977

Ultrasonic characterization of solid renal lesions: echographic, angiographic and pathologic correlation.

Seventy-two patients with solid renal lesions were studied by renal echography and the echography and the results were correlated with angiography and pathologic examination of excised specimens. Thirty-one tumors were diagnosed by echography and were proved by angiography and pathology. Renal tumors are either more echo-producing or less echogenic than adjacent normal renal parenchyma. All angiographically hypervascular tumors and hypovascular tumors with areas of hemorrhage and necrosis are more echo-producing. Hypovascular homogenous renal carcinomas, transitional cell carcinoma invading the kidney, and metastases are less echo-producing. Pseudo-tumors have the same echo characteristics as surrounding and adjacent normal renal parenchyma.

Adenocarcinoma↗
PubMed1977

Ultrasonic distinction of abscesses from other intra-abdominal fluid collections.

The nature of 103 intra-abdominal fluid collections examined by ultrasound was determined by autopsy, needle aspiration, spontaneous drainage or surgical exploration. Abscesses, chronic hematomas, lymphoceles, urinomas, cysts and fluid-filled bowel loops are all approximately elliptical or circular in cross section. Collections of ascites have a very irregular outline. Bowel loops appear as multiple circles, all of similar size. Chronic hematomas contain strongly echoing material, while lymphoceles, urinomas, renal and hepatic cysts and collections of ascites are echo-free. Ovarian cysts into which there has been bleeding may contain echoes. The walls of abscesses, chronic hematomas, and bowel loops are less sharp than the walls of other collections. Intrahepatic abscesses may have more ragged walls than abscesses elsewhere. Ultrasonic characteristics of abscesses and hematomas overlap. It is sometimes possible to distinguish the nature of the fluid by its ultrasonic properties, but atypical appearances are not rare.

Abdomen↗
PubMed1976

An inexpensive photographic strip-chart recorder for use with a commercially available ultrasonic scanner.

A simple arrangement for producing strip-chart records using moving 70mm film and a commercially available motor-driven film magazine is described. The quality of the records is excellent and the cost is about $500. It is necessary to modify the ultrasonic B-mode scanner slightly by connecting the verticle deflection plates of the oscilloscope to one another through an on-off switch.

Humans↗
PubMed1976

Gray-scale ultrasonic properties of the normal and inflamed pancreas.

Eighty-seven examinations of the pancreas in 52 patients with acute or chronic pancreatitis and 31 examinations in 31 normal subjects were reviewed. Demonstration of the portal and splenic veins served as a guidepost to the pancreas. The normal pancreas was indistinguishable from the surrounding tissues in a substantial minority of examinations, and the ultrasonic characteristics of the normal pancreas were quite variable. Acute pancreatitis was found to be characterized by swelling, loss of internal echoes, and loss of distinction between the pancreas and splenic vein. In 50% of patients with chronic inactive pancreatitis, the pancreas could not be identified. Ultrasound should precede endoscopic retrograde cholangiopancreatography whenever a pseudocyst might be present.

Acute Disease↗
PubMed1976

The use of ultrasound in the diagnosis of gastroenterological disease.

Ultrasound is high frequency mechanical vibration. As far as is presently known, there are no harmful effects of ultrasound at the energy levels used in currently available commercial ultrasonic scanners. Ultrasonic studies are independent of organ function, are painless, and require nor special preparation. Ultrasonic scanning is useful in the diagnosis of pancreatic disease, especially in the detection of complications of pancreatitis such as pancreatic abscess or pseudocyst, and in diagnosing pancreatic carcinoma. Gallstones and dilation of the biliary tree can be detected ultrasonically even when the patient is jaundiced. Primary liver tumors and hepatic metastases can often be demonstrated. Intraabdominal abscesses are better investigated by ultrasound than by any other means currently available. Ultrasonic scanning also provides a sensitive means of detecting ascites. Ultrasonic control of needle placement has been suggested for pancreatic and liver biopsy, for aspiration of intraabdominal fluid collections, and for percutaneous transhepatic cholangiography. Ultrasonic B-mode scans provide undistorted images of cross sections through the abdomen which can be used in radiotherapy planning to localize tumor masses and to place kidney shields accurately. Organ volumes can be estimated from a set of ultrasonic B-mode scans without any assumptions being made as to the shape of the organ.

Abdomen↗
PubMed1975

Ultrasonic evaluation of pleural opacities.

Forty-one patients with substantial pleural opacities on chest films were examined by A-mode and B-mode ultrasound. Ultrasonic examination provides an accurate means of differentiating pleural fluid from other conditions which produce such opacities and is superior to the chest films as a means of localizing fluid. With the gain setting used in this series, fluid collections less than 1 cm thick were missed and were probably obscured by reverberation from the ribs. M-mode scanning provides a simple and accurate means of localizing the diaphragm in nearly all patients, almost completely eliminating difficulties caused by subdiaphragmatic placement of the thoracocentesis needle.

Diagnosis, Differential↗
PubMed1975

Xerotomographic diagnosis of central bronchogenic carcinoma.

Xerotomography was used to examine 14 patients with substantial pulmonary opacities, in whom the diagnosis of bronchogenic carcinoma had been suspected. Xerotomography was valuable because it provided excellent delineation of the tracheobronchial tree, which assisted in differentiation of benign from malignant lesions. Malignancy was suggested by: 1) amputation, 2) eccentric narrowing of the bronchus, 3)irregularity of the bronchial wall, 4)presence of an intraluminal mass. Mediastinal and hilar node enlargement could also be assessed. The use of these criteria allowed a correct preoperative diagnosis in 12 of 14 patients. Due to the high radiation dosage, this method is not suitable for use as a screening procedure.

Adult↗