Omental infarct: CT imaging features.

BACKGROUND: The aim of this study is to describe contrast-enhanced computed tomographic (CT) features of acute omental infarction and to study the evolutionary changes on follow-up CT imaging. METHODS: Fifteen cases of omental infarction were evaluated for their initial CT imaging features. The imaging features evaluated included size of the fatty lesion, location, peripheral rim, and relation to colon. CT findings were correlated with etiology, clinical presentation, and leukocytosis. Follow-up CT images were available in eight patients and the imaging features were studied. RESULTS: Eight omental infarcts were of unknown etiology and seven were secondary to abdominal surgery. In 53% of patients (eight of 15), the location of the omental infarct was in the right lower, mid, or upper quadrants. These eight right-side infarcts occurred in six patients with primary omental infarcts. In 13 of 14 patients who underwent CT within 15 days of onset of omental infarct, the margin of the lesion was ill defined. Primary omental (n = 8) infarcts were seen in younger patients (p = 0.02) and were larger on CT (p = 0.02) compared with secondary omental infarcts. CT findings evolved from an ill-defined, heterogeneous fat-density lesion to a well-defined, heterogeneous fat-density lesion with a peripheral hyperdense rim in all six secondary omental infarctions for which acute stage and follow-up CT images were available for interpretation. CONCLUSION: There is a significant difference in the age distribution and CT findings in terms of size of the omental infarction between primary and secondary etiologies. On follow-up CT, secondary omental infarcts progressively shrank and developed a well-defined, hyperdense rim around a fatty core.

Evaluating medical students on radiology clerkships in a filmless environment: use of an electronic test prepared from PACS and digital teaching collection images.

RATIONALE AND OBJECTIVES: The competency of medical students in radiology clerkships is traditionally evaluated with film images, projected slides of photographed films, or printed reproductions of films. As radiology departments switch to filmless imaging, it seemed appropriate to determine the feasibility of an electronic evaluation prepared directly from digital images. MATERIALS AND METHODS: The image-based portion of a multiple-choice final examination was prepared as a PowerPoint presentation that included images downloaded from the departmental picture archiving and communication system (PACS) or digital teaching collections. The images were downloaded as bitmap files, imported to Adobe Photoshop for image editing, converted to tagged image file format, and finally imported to PowerPoint, where they were combined with text to create 50 questions. A liquid crystal diode projector displayed the questions, with a timer set to advance them automatically. RESULTS: The examination was easy and inexpensive to prepare (no photography costs). In an initial survey of 25 students, 17 (71%) of 24 students rated the resolution of images as excellent and five (21%) as good. No student gave an image a poor rating. Students preferred that images cover at least 40%-50% of the slides, and most approved of a blue background. An original allowance of 30 seconds per slide was reported to be too fast; the interval was increased to 45 seconds. CONCLUSION: An electronic final examination for medical students, prepared with images downloaded from PACS or digital teaching collections, is feasible, easy to prepare, and cost-effective, and it provides an excellent display of test images.

Preparing medical students for a filmless environment: instruction on the preparation of electronic case presentations from PACS.

RATIONALE AND OBJECTIVES: As the use of picture archiving and communication systems (PACS) expands and radiology departments become increasingly filmless, it will become increasingly necessary to teach physicians how to use PACS and download diagnostic images. The authors developed an instruction method in which medical students enrolled in a radiology clerkship were taught how to use the PACS, download digital images, and incorporate them into an electronic case presentation. The feasibility and potential benefits of this instructional method were studied prospectively. MATERIALS AND METHODS: Between June and October 1999, all 36 medical students enrolled in Harvard Medical School's core radiology clerkship at Massachusetts General Hospital, Boston, were required to give an electronic radiology case presentation with images downloaded from the departmental PACS. They were taught how to download images, edit them, and then import them into PowerPoint software. They were also given access to the hospital information system to obtain pertinent clinical information. At the formal presentations, the images were displayed with a liquid crystal display (LCD) projector. The students were surveyed on the Ist and last days of the clerkship regarding their learning experiences. RESULTS: Before the radiology clerkship, 81% of the students had never given an electronic presentation with computer and LCD projector, 83% had no PACS experience, and 56% had no PowerPoint experience. All students learned to prepare and deliver electronic presentations of radiologic cases downloaded from PACS. Their presentations were informative, innovative, and entertaining, and the images were well displayed. The students praised the instruction highly and thought their new skills would serve them well. CONCLUSION: Teaching medical students how to prepare and deliver electronic presentations of radiologic cases downloaded from PACS proved to be very feasible and well appreciated by the students.

Impact of PACS on the education of radiology residents: the residents' perspective.

RATIONALE AND OBJECTIVES: Because digital imaging and the picture archiving and communication system (PACS) are replacing radiographic film, the effect of PACS on residents' perceptions and their educational experience was investigated. MATERIALS AND METHODS: Residents taking part in large diagnostic radiology training programs at two hospitals were surveyed. Approximately 75% of radiographic studies were reviewed with the use of PACS at both hospitals. Survey topics included technical and didactic issues based on direct and indirect comparison with analog (conventional film) images. RESULTS: Fifty residents were polled (20 respondents). The majority has been using PACS for more than 1 year (14 of 20, 70%) to interpret 75%-100% of cases (11 of 20, 55%). The majority believed that PACS improved patient care (15 of 20, 75%) and their educational experience (15 of 20, 75%). A minority believed that increased patient throughput was harmful to the educational experience (five of 20, 25%) because it permitted attending radiologists to review cases too quickly (four of 20, 20%). Residents favored PACS over hard-copy images for ease of manipulation, resolution, and ability to see pathologic conditions and normal anatomic characteristics. CONCLUSION: Residents believe that PACS has positively affected their learning experience and does not negatively affect the quality of resident education.

Clinical competence assessment in radiology: introduction of an objective structured clinical examination in the medical school curriculum.

RATIONALE AND OBJECTIVES: Traditional oral and written examinations can be limited in predicting future clinical performance. Therefore Objective Structured Clinical Examinations (OSCEs) have been introduced in other specialties. The authors assessed their value in radiology. MATERIALS AND METHODS: The study includes 122 Harvard medical students who undertook 1-month compulsory clerkships at one of three hospitals (A, B, or C) in their 3rd and 4th year and a compulsory OSCE in their 4th year. The OSCE was constructed from five cases. Each had eight or nine standardized questions designed to test, within a set time, the perception of essential findings, their interpretation, and clinical judgment (maximum possible score, 100). Clerkship grades were high honors (score of 3), honors (score of 2), satisfactory (score of 1), and fail (score of 0). Predictors of OSCE scores-clerkship grade and affiliated hospital-were modeled as linear functions. Time elapsed between clerkship and OSCE was modeled as a nonlinear function. RESULTS: Although there was a positive relation between clerkship grade and OSCE grade, it accounted for an increase of only 5.7% in OSCE score per clerkship grade and did not predict performance of individual students. Students who trained in hospital B showed significantly higher OSCE grades. OSCE scores were highest when the examination was taken 8 months after the clerkship. CONCLUSION: The OSCE may be useful to uncover deficits in individuals and groups beyond the ones detected with traditional clerkship evaluations and provide guidance for remediation. The improved performance after additional clinical exposure suggests that the OSCE may be well suited to test the integration of radiologic and clinical knowledge.

Evaluation of suspected appendicitis in children using limited helical CT and colonic contrast material.

OBJECTIVE: Colonic contrast material evaluation of suspected appendicitis in pediatric patients is technically more challenging than in adults because less intraabdominal fat is present. To determine the accuracy and feasibility of focused CT for pediatric patients, we carried out this retrospective investigation. MATERIALS AND METHODS: Between November 1995 and July 1999, 199 pediatric patients (1-18 years old; mean age, 12 years) were examined with focused CT in the emergency division for suspected appendicitis. The findings on CT were compared with the findings at surgery, pathology, and clinical follow-up. RESULTS: There were 64 true-positive CT scans, two false-negative, 128 true-negative, one false-positive, and four indeterminate. Seventy-four patients underwent appendectomy, with a negative appendectomy rate of 9%. One hundred twenty-five patients without appendicitis were treated nonoperatively. The true-positive rate was 32%, true-negative rate was 64%, sensitivity was 97%, specificity was 99%, positive predictive value was 98%, negative predictive value was 98%, and overall accuracy was 96%. Pediatric patients tolerated the procedure well. Colonic contrast material saved time and provided improved identification of the cecum and appendix. In 62 patients without appendicitis, focused CT provided alternative diagnoses. CONCLUSION: Focused CT appears to be nearly as accurate in pediatric patients as in adults. Focused CT provided alternative diagnoses in 48% of the patients for whom CT findings were negative for appendicitis.

Plain abdominal radiographs and abdominal CT scans for nontraumatic abdominal pain--added value?

We conducted a retrospective descriptive study to determine the value of plain abdominal radiographs in emergency department (ED) patients also receiving abdominal computed tomography scans (CT) for the evaluation of nontraumatic abdominal, back and flank pain (NTAP). Cases were identified through radiology log books. Medical records and radiology reports were reviewed to determine whether the CT confirmed the findings of the plain abdominal radiographs, and whether the clinical course confirmed the results of either. Test characteristics for the plain abdominal radiograph and for the CT, using the clinical course including subsequent invasive procedures as the gold standard, were calculated. Of 177 patients who received CTs, 97 (55%) also received plain abdominal radiographs. Among the 74 patients who were admitted to the hospital and had complete data, the sensitivity and specificity for the plain abdominal radiographs were .43 and .75 respectively, compared to .91 and .94 for the CT scan (P(sens.) < .05, P(spec.) < .05). In 4 patients (5%), both studies failed to identify pathology shown in a subsequent procedure. In ED patients with NTAP, the plain abdominal radiograph may have some value as a screening tool; however, in patients in whom a CT is likely to be ordered anyway, a plain abdominal radiograph is unhelpful and often misleading.

Helical CT in emergency radiology.

Today, a wide range of traumatic and nontraumatic emergency conditions are quickly and accurately diagnosed with helical computed tomography (CT). Many traditional emergency imaging procedures have been replaced with newer helical CT techniques that can be performed in less time and with greater accuracy, less patient discomfort, and decreased cost. The speed of helical technology permits CT examination of seriously ill patients in the emergency department, as well as patients who might not have been taken to CT previously because of the length of the examinations of the past. Also, helical technology permits multiple, sequential CT scans to be quickly obtained in the same patient, a great advance for the multiple-trauma patient. Higher quality CT examinations result from decreased respiratory misregistration, enhanced intravenous contrast material opacification of vascular structures and parenchymal organs, greater flexibility in image reconstruction, and improved multiplanar and three-dimensional reformations. This report summarizes the role and recommended protocols for the helical CT diagnosis of thoracic aortic trauma; aortic dissection; pulmonary embolism; acute conditions of the neck soft tissues; abdominal trauma; urinary tract stones; appendicitis; diverticulitis; abdominal aortic aneurysm; fractures of the face, spine, and extremities; and acute stroke.

Helical CT of appendicitis and diverticulitis.

The clinical diagnosis of appendicitis and diverticulitis remains challenging. Clinical diagnosis alone can lead to unnecessary hospitalizations and surgeries, prolonged periods of hospital observation, and delays prior to necessary medical or surgical treatment. Helical CT combined with recently reported techniques for imaging appendicitis and diverticulitis offers rapid and accurate confirmation or exclusion of these entities as well as identification of alternative conditions that can clinically mimic them. More routine use of helical CT holds great promise for improving patient care and lowering hospital resource use in patients with clinically suspected appendicitis and diverticulitis.

Helical CT and three-dimensional CT of facial and orbital injury.

Knowledge of the regions of the face and their buttresses and knowledge of the types of facial injuries frequently encountered simplifies the diagnostic task. The indications for CT include detection of suspected fractures and preoperative planning. The cost of facial CT to the hospital has declined and is little different than the cost of plain films. CT may become the screening modality of choice depending on the cost structure at any given hospital.

Helical CT of abdominal trauma.

CT has revolutionized the diagnostic work-up of trauma patients with suspected abdominal injuries. A wide range of intraperitoneal and retroperitoneal organ injuries can be quickly and accurately diagnosed with CT. Today, helical CT technology permits even faster examinations, with improved intravenous contrast opacification of parenchymal organs and vascular structures and reduced CT artifacts caused by patient motion, respiration, and arterial pulsation. Severely injured and potentially unstable patients, who might not have been able to tolerate the long CT examinations of the past, may be quickly evaluated today with helical CT. Accurate diagnosis requires high quality CT examinations that are performed with optimum CT protocols. This article reviews the currently recommended helical CT protocols for evaluating patients with suspected abdominal injuries, and the CT findings when injuries are present.

Introduction of appendiceal CT: impact on negative appendectomy and appendiceal perforation rates.

UNLABELLED: OBJECTIVE To evaluate the impact of appendiceal computed tomography (CT) availability on negative appendectomy and appendiceal perforation rates. SUMMARY BACKGROUND DATA: Appendiceal CT is 98% accurate. However, its impact on negative appendectomy and appendiceal perforation rates has not been reported. METHODS: The authors reviewed the medical records of 493 consecutive patients who underwent appendectomy between 1992 and 1995, 209 consecutive patients who underwent appendectomy in 1997 (59% of whom had appendiceal CT), and 206 patients who underwent appendiceal CT in 1997 without subsequent appendectomy. RESULTS: Before appendiceal CT, 98/493 patients (20%) taken to surgery had a normal appendix. After CT availability, 15/209 patients (7%) taken to surgery had a normal appendix; 7 patients did not have CT, 5 patients had surgery despite a negative CT, and 3 patients had a false-positive CT. Negative appendectomy rates were lowered overall (20% to 7%), in men (11% to 5%), in women (35% to 11%), in boys (10% to 5%), and in girls (18% to 12%). Appendiceal perforation rates dropped from 22% to 14% after CT availability. CT excluded appendicitis in 206 patients in 1997 who avoided appendectomy and identified alternative diagnoses in 105 of these patients (51%). CONCLUSION: The availability of appendiceal CT coincided with a drop in the negative appendectomy rate from 20% to 7% in all patients, and to only 3% in patients with a positive CT. Perforation rates decreased from 22% to 14%. Appendiceal CT can be advocated in nearly all female and many male patients.

Helical computed tomography in differentiating appendicitis and acute gynecologic conditions.

OBJECTIVE: To determine the accuracy and effect of helical computed tomography (CT) in women clinically suspected of having either appendicitis or an acute gynecologic condition. METHODS: One hundred consecutive nonpregnant women suspected of having appendicitis or an acute gynecologic condition prospectively had helical CT. Interpretations were correlated with surgical and pathologic findings (41 cases) and clinical follow-up for at least 2 months (59 cases). The accuracy for confirming or excluding both appendicitis and acute gynecologic conditions was determined. The effect on patient care was determined by comparing pre-CT plans with actual treatment. RESULTS: Thirty-two women had appendicitis, 15 had acute gynecologic conditions, 27 had other specific diagnoses, and 26 had nonspecific abdominal pain. For diagnosing appendicitis or acute gynecologic conditions, CT had 100% and 87% sensitivity, 97% and 100% specificity, 94% and 100% positive predictive value, 100% and 98% negative predictive value, and 98% and 98% accuracy, respectively. After CT was done, 36 planned hospital admissions, 25 planned hospital observations, and six planned appendectomies were deferred; six women had alternative surgical procedures on the basis of CT results. One patient had an unnecessary appendectomy on the basis of CT findings. CONCLUSION: Helical CT is an excellent imaging option for differentiating appendicitis from most acute gynecologic conditions.

Head trauma: CT scan interpretation by radiology residents versus staff radiologists.

PURPOSE: To determine the rate and clinical outcome of discrepancies in interpretation by radiology residents and staff neuroradiologists of posttraumatic cranial computed tomographic (CT) scans. MATERIALS AND METHODS: Prospective evaluation was performed for 419 consecutive emergency posttraumatic cranial CT studies that had been interpreted by radiology residents on call over a 16-month period. Discrepancies between the interpretations made by residents and those made by staff radiologists were divided into two groups: failure to recognize an abnormality (false-negative finding) and interpretation of normal as abnormal (false-positive finding). Discrepancies were considered major if they could affect patient care in the emergency setting and minor if they could not. RESULTS: Major and minor discrepancies were 1.7% and 2.6%, respectively, among interpretations made by residents and those by staff radiologists. Major discrepancies were four subdural hematomas, one pneumocephalus, one hemorrhagic contusion, and one subarachnoid hemorrhage. Minor discrepancies included six skull and five facial fractures. The discrepancy rate was statistically significantly higher (12.2%) when CT findings were abnormal than when they were normal (1.5%). No change in treatment was attributed to the delay in diagnosis. CONCLUSION: A low discrepancy rate was found between interpretations made by radiology residents and those made by staff neuroradiologists of posttraumatic cranial CT scans. There were no adverse clinical outcomes.

Helical CT with only colonic contrast material for diagnosing diverticulitis: prospective evaluation of 150 patients.

OBJECTIVE: We prospectively evaluated a helical CT technique in which contrast material is administered only through the colon for the imaging of suspected diverticulitis. SUBJECTS AND METHODS: One hundred fifty consecutive patients who presented to our emergency department with clinically suspected diverticulitis underwent helical abdominal CT after contrast material was administered only through the colon. CT findings of diverticulitis included diverticula, muscular wall hypertrophy, focal colonic wall thickening, and pericolonic fat stranding. CT results were correlated with clinical follow-up (all patients) and with pathologic findings (41 patients). RESULTS: A final clinical diagnosis of diverticulitis was made in 64 patients (43%), of whom 62 (97%) had CT results positive for diverticulitis. Of the 86 patients for whom diverticulitis was clinically excluded, all (100%) had CT results that were negative for diverticulitis. CT interpretations had a sensitivity of 97%, a specificity of 100%, a positive predictive value of 100%, a negative predictive value of 98%, and an overall accuracy of 99%. Alternative diagnoses were noted on CT in 50 (58%) of 86 patients who did not have diverticulitis and included 50 (78%) of the 64 patients in whom an alternative condition other than nonspecific abdominal pain was established. CONCLUSION: Helical CT obtained after contrast material administered only through the colon is accurate (99%) for confirming or excluding clinically suspected diverticulitis and for suggesting alternative conditions (78%) when they are present. This CT technique avoids the risks, discomforts, and costs of oral and i.v. contrast material administration and allows immediate scanning.