Barbara C. Good

The effect of clinical history on chest radiograph interpretations in a PACS environment.

The effect that accompanying patient information has on diagnostic accuracy in radiologic interpretation has been studied by many researchers but remains a matter of contention. Experiments in the past emphasized the chest film because this procedure is the one done most frequently in radiology. However, with the increasing importance of digital imaging, the role of patient history in these procedures should be assessed. The use of a model computerized patient history in the interpretation of digitized chest images that were displayed on a high-resolution workstation was studied. Two hundred forty-seven selected posteroanterior chest images that indicated disease and that indicated no disease were interpreted in random sequence by five board-certified radiologists, with and without accompanying patient histories. Readers were prompted by the response forms to evaluate images for the possible occurrence of interstitial diseases, nodules, or pneumothorax. No significant differences (P = .05) in the detection of these abnormalities were noted between case readings with and without history for any of the radiologists or for the group as a whole. However, this methodology reflects a direct interpretation approach. The results of this study may not necessarily be applicable to individual prompts, different imaging procedures, or other abnormalities.

Xenon/CT blood flow mapping of the kidney and liver

A noninvasive technique for measuring blood flow by xenon-enhanced X-ray transmission CT has been developed and reported quite extensively in recent years. In this method nonradioactive xenon gas is inhaled, and the temporal changes in radiographic enhancement produced by the inhalation are measured by sequential CT. Time-dependent xenon concentration within various tissue segments is used to derive local blood flow maps. The method has been amply discussed in relation to assessment of local cerebral blood flow. Its application to other body organs is explored in this paper, in which results from six preliminary blood flow studies in the liver and kidneys of nonhuman primates are reported. Blood flow in renal cortex ranged from 150 to 280 ml/100 cc/min and hepatic tissue perfusion from 80 to 120 ml/100 cc/ min. The advantages and limitations of the method in such applications are discussed.

Local cerebral blood flow alterations (Xe-CT method) in an accident victim

Computed tomography was used before and during inhalation of nonradioactive xenon gas to measure and map local cerebral blood flow noninvasively at two PaCO2 levels in a 19-year-old accident victim. The technique demonstrated normal response to elevated PaCO2 with only a regional loss of autoregulation.

X-Ray Imaging With Two-Dimensional Charge-Coupled Device (CCD) Arrays

Two basic approaches to digital radiography have been thoroughly investigated in the last decade. In one, the traditional video chain is modified, and the output of the camera is digitized and analyzed by a computer to produce an image of the area of the body being examined. The other approach uses a linear detector array to generate a sequential series of line images as the array is scanned across the area being observed; the line images are then combined by a computer to form a two-dimensional image. We are investigating the characteristics of a third method, a prototype digital radiography system in which two-dimensional diode arrays (CCD) are fiberoptically coupled directly to either a scintillating fiberoptic plate or to a fluorescent screen. In this paper we describe the- concepts and design configuration of this approach, as well as preliminary results from several phantom studies. Our results indicate that high resolution, high signal-to-noise ratio imaging can be attained with this method.

Radiologists' Perceptions Of And Preferences For A Concise Computerized History Form During Radiologic Interpretations

The purpose of this study was to develop and design a model computerized patient history form that could be used by practicing radiologists during the x-ray reading and interpretation process. We conducted a multi-observer study to determine 1) whether such a form is warranted and can be a feasible part of the reading process; and 2) what the component parts of the form and their order of appearance in the form should be. Twenty board-certified radiologists were tested in their areas of subspecialty; each radiologist read a series of 10 cases, half with and half without clinical histories. Results indicated that all those tested would use such a history if it were provided to them along with the radiographs to be read; that they prefer such a history to be brief but detailed enough to provide more information than the typical requisition does; that they prefer a rapidly accessible history; and that there are preferences about what information appears and the order in which it appears.

Training observers for receiver operating characteristic studies

In an ongoing, multi-reader, multi-project program dealing with the interpretation of radiological images, we have examined several issues of methodology which have not as yet been addressed that may impact on the determination of reader performance as measured by receiver operating characteristic (ROC) analysis. Among these are issues associated with the training of observers prior to such studies. We employed three types of observer training that we found to be necessary for the successful performance of such studies: 1) a general instructional session for observers on the study protocol and system operation; 2) practice with an interactive computerized feedback teaching file that demonstrates the imaging systems and familiarized readers with an idea of the types of cases that were used in the study along with their correct diagnoses; and 3) training sessions in which readers were taught the manner in which to distribute answer ratings over an ordinal confidence scale. The possible effect of such types of training on the performance and results of ROC studies should be carefully considered prior to their commencement.

Exploring computerized mammographic reporting with feedback

Computer-aided diagnosis is generally dependent on feature detection and identification on digitized images. In this project, we explored the use of a computerized system in which features identified by radiologists for a previous set of mammography cases, in addition to other information on those cases, formed a database of information that provided readers of new cases with statistical probabilities (feedback) for malignancy in similarly rated cases. Although in this preliminary study the feedback system did not improve levels of diagnostic accuracy (which were already high), the results suggest that in certain settings and with certain mammography readers the method may be extremely promising.