Search PubMed⌕ Search

Biomedical subjects

L L Fajardo

Publications and source records attributed to L L Fajardo.

68 records · Page 4Linked to original sources
PubMed1989

Detection of pneumothorax: comparison of digital and conventional chest imaging.

To investigate radiologists' performance at interpreting digital radiographic images, we compared the detectability of pneumothoraces on computed radiographic chest images with 0.2-mm pixel size (2.5 Ip/mm) with their detectability on matched conventional screen-film images (5 Ip/mm). Eight radiologists reviewed 50 computed and 50 screen-film chest radiographs from 25 patients with pneumothoraces and 25 patients with other (or no) abnormalities. Four of the readers who best detected pneumothoraces on screen-film examinations performed worse when interpreting computed radiographic studies; the other four readers detected pneumothoraces similarly with both techniques. No relationship was found between the size of a pneumothorax and its likelihood of detection by either technique. These results raise concerns about implementing computed radiography for comprehensive chest imaging.

Adult↗
PubMed1989

The lack of sonographic image degradation after barium upper gastrointestinal examination.

The presence of barium in the gastrointestinal tract after barium studies of the stomach and colon is thought to interfere with the performance of abdominal sonography. This notion results in delays in diagnosis and scheduling inconveniences when both studies are indicated at the same time. To determine if this belief is true, we prospectively obtained sonograms before and after biphasic upper gastrointestinal examinations in 40 patients. The 80 sonograms were randomized and blindly interpreted by two radiologists who used a scale from 0 to 4 to rate the appearance of six anatomic areas (gallbladder, pancreas, aorta, porta hepatis, and right and left lobes of the liver). The results showed no degradation of the image of these structures on the sonograms obtained after the barium meal compared with the prebarium sonograms. We conclude that barium does not interfere with sonography performed immediately after an upper gastrointestinal examination. Consequently, when both studies are needed, a sonogram can be scheduled after an upper gastrointestinal exam.

Abdomen↗
PubMed1989

Evaluation of contrast dose reduction for excretory urography using computed radiography.

We prospectively investigated whether performing excretory urography by computed radiography (CR) - with CR's broader dynamic range and potential for post-processing - would permit lower contrast dose while maintaining usual image quality. The rationale for this experiment was to evaluate whether CR had potential in reducing the risks and costs associated with urography. Sixty sequential patients were randomly assigned to undergo computed urography with either our full (282 mg I/kg body weight) or half our usual dose (141 mg I/kg body weight) of intravenous 60% diatrizoate meglumine. Three blinded observers judged automatically post-processed full dose tomograms and KUBs as qualitatively superior to both automatically post-processed and individually, interactively post-processed half dose images. Thus, post-acquisition image manipulation could not fully compensate for diminished image quality due to contrast dose reduction.

Diatrizoate Meglumine↗
PubMed1988

Image quality, diagnostic certainty, and accuracy: comparison of conventional and digital urograms.

Our previous research showed that radiologists could interpret digital urograms with sensitivity, specificity, and receiver operating characteristic (ROC) curve performance similar to their interpretations of conventional urograms. To evaluate further the suitability of digital radiology for performing excretory urography, we investigated relationships among image quality, radiologists' certainty of diagnostic decisions, and diagnostic accuracy for digital and conventional urograms. We examined data from a study of 100 excretory urograms performed using matched film-screen and digital exposures. Three radiologists rated the quality of digital urographic images compared to film-screen images. Image quality did not correlate well with diagnostic accuracy for either modality, perhaps because of the overall high level of quality of the exposures. Radiologists' level of certainty in their diagnostic decisions decreased with poorer image quality for both modalities. The similarities of the tested relationships provides further evidence that digital technology is suitable for use in urography.

Humans↗
PubMed1988

Computed tomography findings in squamous cell carcinoma of the pancreas.

This case illustrates previously unreported computed tomography findings in a primary pancreatic squamous cell carcinoma, an unusual pancreatic malignancy. With bolus injection of intravenous contrast, attenuation of this tumor increased from 35 to 61 Hounsfield units, a finding not typical for pancreatic adenocarcinoma.

Biopsy, Needle↗
PubMed1988

Correlation between breast parenchymal patterns and mammographers' certainty of diagnosis.

The density of breast tissue on a mammogram may affect radiologists' diagnostic decisions. To evaluate possible correlations among breast parenchymal pattern and diagnostic confidence, six radiologists classified 655 mammograms as N1, P1, P2, and DY, according to Wolfe's criteria. Evaluation of radiologists' confidence interpreting the mammograms (1 = absolutely certain, 2 = fairly certain, 3 = uncertain), shows a significant correlation between decreasing diagnostic certainty and increasing complexity of the mammographic breast parenchymal pattern. That readers are less confident in their interpretation of P2 and DY breast parenchymal patterns has implications for the operation of breast cancer screening programs.

Breast↗
PubMed1988

Radiologic appearance of the Jarvik artificial heart implant and its thoracic complications.

The principles of total artificial heart devices, their radiologic appearance, and the complications associated with their use have become increasingly relevant as these devices are used more often in patients with end-stage cardiac disease. The Jarvik artificial heart implant is the one used most frequently. Intrathoracic complications related to its use were evaluated radiographically in seven patients undergoing implantation at our institution. Because of the relatively large size of the device, complications from compression of the left lung are common. Four of the seven patients had prolonged atelectasis of the left lower lobe and two had major vascular compression (pulmonary veins in the left lung in one and the inferior vena cava in another). Other chest complications were infection in the surgical site (three patients), mediastinal bleeding (one patient), and extensive fibrous adhesions around the device, making explantation difficult (one patient). All seven patients had pulmonary edema before surgery, which regressed over several days after surgery. Radiographs readily display the major components of the Jarvik heart and are valuable for detecting pulmonary complications associated with its use.

Adult↗
PubMed1987

AUR memorial award--1987. The impact of focused instruction on learning mammography.

Recent promotion of breast cancer screening has increased the demand for mammography services and well-trained mammographers. To determine whether focused instruction, which may occur in continuing medical education courses, is effective in imparting mammography skills and knowledge, an instructional program was developed and evaluated. Seventeen physicians were tested before and after six 1-hour instructional sessions about breast disease and cancer screening, mammogram interpretation, and determining appropriate patient disposition. Twelve weeks after instruction, subjects demonstrated significant improvement in factual knowledge, in decision-making ability regarding patient disposition, and in recognition of benign disease on mammograms. There also was significant improvement in specificity, but no improvement in cancer detection. Further, no correlation between participants' subjective self-assessment of improvement and their actual performance on the postinstruction evaluation was found. Evaluation of instructional programs is necessary to determine their effectiveness, and promotes improvement in instructional offerings.

Breast Neoplasms↗
PubMed1987

Excretory urography using computed radiography.

A computed radiographic system for generating digital film images was evaluated in the performance of excretory urography. Three experienced radiologists reviewed digital and conventional screen-film urograms for 100 patients in a prospective study to evaluate the clinical utility of the digital system. Results indicate no difference between digital and screen-film urograms in diagnostic sensitivity, specificity, or receiver-operating-characteristic curves for differentiating normal from abnormal studies. Readers' performances in making specific diagnoses were also the same with both techniques.

Humans↗
PubMed1987

Mammogram interpretation by physician assistants.

The objective of this study was to determine whether a health maintenance organization (HMO) desirous of providing low-cost, quality mammography could employ physician assistants (PAs) to interpret mammograms under the supervision of HMO radiologists. After intensive training in mammographic interpretation, four PAs individually interpreted 727 mammograms of 470 normal breasts, 75 breasts with benign breast masses, and 182 breasts with cancer. The interpretations by the PAs were more sensitive and as specific as those made by six HMO radiologists who interpreted the same cases, and as effective as those by radiologists described in the literature. In receiver-operating-characteristic curve analysis, the areas under curves for PAs were larger than those under curves for radiologists. Interpretations by PAs took less time and cost less than did those by radiologists; the dispositions recommended by PAs were similar to those recommended by radiologists. We conclude that properly trained, evaluated, and supervised PAs can interpret mammograms. Legal, practical, and ethical considerations dictate that this can best be accomplished under the direction of radiologists who are well trained in mammography.

Female↗
PubMedDate not supplied

Image processing algorithms for digital mammography: a pictorial essay.

Digital mammography systems allow manipulation of fine differences in image contrast by means of image processing algorithms. Different display algorithms have advantages and disadvantages for the specific tasks required in breast imaging-diagnosis and screening. Manual intensity windowing can produce digital mammograms very similar to standard screen-film mammograms but is limited by its operator dependence. Histogram-based intensity windowing improves the conspicuity of the lesion edge, but there is loss of detail outside the dense parts of the image. Mixture-model intensity windowing enhances the visibility of lesion borders against the fatty background, but the mixed parenchymal densities abutting the lesion may be lost. Contrast-limited adaptive histogram equalization can also provide subtle edge information but might degrade performance in the screening setting by enhancing the visibility of nuisance information. Unsharp masking enhances the sharpness of the borders of mass lesions, but this algorithm may make even an indistinct mass appear more circumscribed. Peripheral equalization displays lesion details well and preserves the peripheral information in the surrounding breast, but there may be flattening of image contrast in the nonperipheral portions of the image. Trex processing allows visualization of both lesion detail and breast edge information but reduces image contrast.

Algorithms↗
PubMedDate not supplied

Stereotactic core-needle biopsy of the breast: a report of the Joint Task Force of the American College of Radiology, American College of Surgeons, and College of American Pathologists.

A national task force consisting of members from the American College of Radiology, the American College of Surgeons, and the College of American Pathologists examined the issues surrounding stereotactic core-needle biopsy for occult breast lesions. Their report includes indications and contraindications, informed consent, specimen handling, and management of indeterminate, atypical, or discordant lesions.

Biopsy, Needle↗