Radiology resident evaluation of head CT scan orders in the emergency department

BACKGROUND AND PURPOSE: Prior studies have revealed little difference in residents' abilities to interpret cranial CT scans. The purpose of this study was to assess the performance of radiology residents at different levels of training in the interpretation of emergency head CT images. METHODS: Radiology residents prospectively interpreted 1324 consecutive head CT scans ordered in the emergency department at the University of Arizona Health Science Center. The residents completed a preliminary interpretation form that included their interpretation and confidence in that interpretation. One of five neuroradiologists with a Certificate of Added Qualification subsequently interpreted the images and classified their assessment of the residents' interpretations as follows: "agree," "disagree-insignificant," or "disagree-significant." The data were analyzed by using analysis-of-variance or chi-squared methods. RESULTS: Overall, the agreement rate was 91%; the insignificant disagreement rate, 7%; and the significant disagreement rate, 2%. The level of training had a significant (P =.032) effect on the rate of agreement; upper-level residents had higher rates of agreement than those of more junior residents. There were 62 false-negative findings. The most commonly missed findings were fractures (n = 18) and chronic ischemic foci (n = 12). The most common false-positive interpretations involved 10 suspected intracranial hemorrhages and suspected fractures. CONCLUSION: The level of resident training has a significant effect on the rate of disagreement between the preliminary interpretations of emergency cranial CT scans by residents and the final interpretations by neuroradiologists. Efforts to reduce residents' errors should focus on the identification of fractures and signs of chronic ischemic change.     

Clinical consequences of misinterpretations of neuroradiologic CT scans by on-call radiology residents

BACKGROUND AND PURPOSE: Studies have looked at the accuracy of radiologic interpretations by radiology residents as compared with staff radiologists with regard to emergency room plain films, emergency room body CT scans, and trauma head CT scans; however, to our knowledge, no study has evaluated on-call resident interpretations of all types of neuroradiologic CT scans. Both as a part of our departmental quality control program and to address concerns of clinical services about misinterpretation of neuroradiologic CT scans by on-call radiology residents, we evaluated the frequency of incorrect preliminary interpretations of neuroradiologic CT scans by on-call radiology residents and the effect of such misinterpretations on clinical management and patient outcome. METHODS: As determined by the staff neuroradiologist the next day, all potentially clinically significant changes to preliminary reports of emergency neuroradiologic CT scans rendered by on-call radiology residents were recorded over a 9-month period. A panel of neuroradiologists reviewed and graded all the changed cases by consensus. An emergency department staff physician reviewed medical records of all submitted cases to determine clinical consequences of the misinterpretations. RESULTS: Significant misinterpretations were made in 21 (0.9%) of 2388 cases during the study period. There was a significant change in patient management in 12 of the cases, with a potentially serious change in patient outcome in two cases (0.08%). CONCLUSION: On-call radiology residents have a low rate of significant misinterpretations of neuroradiologic CT scans, and the potential to affect patient outcome is rare.     

Comparison of emergency cranial CT interpretation between radiology residents and neuroradiologists: transverse versus three-dimensional images

PURPOSE

Three-dimensional (3D) reformatted images provide a more inclusive representation of abnormalities than transverse images in cranial computed tomography (CT). The purpose of this study was to assess the value of 3D reformations for radiology residents in the interpretation of emergency cranial CTs.

MATERIALS AND METHODS

In total, 218 consecutive patients who underwent emergency cranial CT scans with 3D reformation were included in this retrospective study. Four blinded readers (three radiology residents and a neuroradiologist) interpreted the transverse and 3D images in two separate sessions. Each reader assessed 1) abnormal finding(s) and the confidence score(s) (5-point scale) for transverse and 3D images, 2) added value score of 3D images (5-point scale), and 3) interpretation time for both transverse and 3D images. We analyzed discordance between each radiology resident and the neuroradiologist on a lesion-by-lesion basis.

RESULTS

In total, 509 lesions were detected in 218 patients. Discordance rates between the three residents and the neuroradiologist were 11.4%–20.2% (mean, 15.0%) and 8.8%–16.9% (mean, 12.1%) in the interpretation of transverse and 3D images, respectively. Confidence scores were higher for 3D images than for transverse images for all readers. The added value scores for the 3D images were relatively higher for the inexperienced residents. Interpretation times for 3D images were significantly higher than for transverse images for all readers.

CONCLUSION

The 3D reformations assist radiology residents in the interpretation of emergency cranial CT examinations.Unenhanced cranial computed tomography (CT) is the primary imaging modality for the emergency evaluation of patients with acute neurological deficits because of its wide availability, speed, costeffectiveness, and ability to assess less stable patients (1). Although some institutions may have 24-hour CT interpretation by an experienced neuroradiologist, many hospitals provide overnight coverage for CT studies by an on-call radiology resident. The final interpretation is then provided by attending neuroradiologists, usually the next day. Thus, accurate initial interpretation of cranial CT scans by the resident is critical for proper patient management.A few studies have investigated discordance between radiology residents and neuroradiologists in the interpretation of unenhanced cranial CT scans and they reported discordance rates in the range of 2.1%–8.3% (2–4). This discordance rate may be influenced by several factors, such as the resident’s level of training, prevalence and type of disease, and imaging technique (e.g., resolution, display, image plane).A few studies have assessed the added value of three-dimensional (3D) reformations versus transverse plane views in the evaluation of cranial CT examinations (5, 6). To our knowledge, however, no reported study has evaluated the effect of 3D reformatted images on radiology residents’ performance.The aim of this study was to assess the value of 3D reformations to radiology residents in the interpretation of unenhanced emergency cranial CT scans.     

Overnight resident preliminary interpretations on CT Examinations: should the process continue?

We report our experience with resident preliminary interpretations given at night on both abdominal and neurological CT scans to quantify the discrepancy rate when compared to the final report. An attempt was also made to document any adverse clinical outcomes as a result of the preliminary interpretation. From January 1, 2004 to December 31, 2004, adult CT examinations were prospectively interpreted by residents at night at a level I trauma center. Both the neurological and body CT scans were reviewed beginning at 7:00 a.m. the following morning by the respective subspecialty staff and discrepancies were noted. Adult CT examinations (6,858) were prospectively interpreted by residents: 5,206 cranial spinal CT examinations and 1,652 body CT examinations. Among the neurological studies, there were six cases identified as major discrepancies (0.1%) and 185 minor discrepancies (3.5%). Among the body CT cases, there were seven cases identified as major discrepancies (0.4%) and 23 cases of minor discrepancies (1.4%). There is a low discrepancy rate (0.2% major and 3.1% minor) in the preliminary resident interpretations from the final report. The process of overnight preliminary CT interpretations should continue as it is not substandard care.Presented at the American Society of Emergency Radiology 2005 Annual Meeting, Tucson, Arizona.     

Evaluation of personal digital assistants as an interpretation medium for computed tomography of patients with intracranial injury

The objective of the study was to assess the feasibility of using a personal digital assistant (PDA) as a medium for the interpretation of cranial CT scans of trauma patients. Twenty-one noncontrast cranial CT scans were transferred in their entirety to a PDA from the picture archiving and communications system (PACS) utilizing General Electric (GE) PathSpeed PACS Web Server interface and synchronization. All CT scans had been interpreted by board-certified radiologists prior to the study. Seven of the scans demonstrated subarachnoid hemorrhage, seven demonstrated subdural hematomas, and the remaining scans were normal. After transfer to the PDA, all images were separately reviewed in a blinded manner by a radiologist and a neurosurgeon. Images were graded for their quality and diagnostic utility in the evaluation of intracranial hemorrhage. Image quality was categorized as excellent, very good, acceptable for diagnosis, or not acceptable for diagnosis. Based on the radiologic diagnosis, recommendation for surgical management was made by the reviewing neurosurgeon. The accuracy rate for both the radiologist and the neurosurgeon in the detection of intracranial hemorrhage was 95%. There was one false negative which was attributed to error in judgment rather than poor image quality. This diagnostic error did not affect patient management. The sensitivity and specificity for detection of intracranial hemorrhage were 93% and 100%, respectively. Image quality was judged to be excellent in 90% of the cases and very good in the remaining 10%. Our results suggest that the PDA is a robust medium for interpretation of CT scans in patients with suspected hemorrhage following intracranial injury. In this setting, the PDA should be considered for teleradiology purposes.     

Cranial CT interpretation by senior emergency department staff

The aims of the present study were to determine the rate of misinterpretation of non-contrast cranial CT scans by emergency specialists and trainees compared with specialist radiologists, and the proportion of misinterpretations that is consequential. A 12-month prospective blinded cohort study was performed. One-hundred and ninety of 1,282 scans (14.8%) were misinterpreted, and 78 of these (41.1%) were of potential or actual consequence. We conclude that the performance of senior emergency department staff in non-contrast cranial CT interpretation is no better than moderately good, and a large proportion of misinterpretations are of potential or actual clinical consequence.     

Evaluation of emergency CT scans of the head: is there a community standard?

OBJECTIVE: This study was designed to assess the accuracy of general radiologists in the interpretation via teleradiology of emergency CT scans of the head. MATERIALS AND METHODS: We studied the interpretations of 716 consecutive emergency CT scans of the head by a group of 15 board-certified general radiologists practicing in the community (as opposed to an academic setting). The scans were sent via teleradiology, and the preliminary interpretations were made. Three of the general radiologists were functioning as nighthawks, and the remaining 12 were acting as on-call radiologists in addition to their normal daytime duties. Each CT examination was interpreted by one of five neuroradiologists the day after the initial interpretation had been performed. The findings of the final interpretation and the preliminary interpretation were categorized as showing agreement, insignificant disagreement, or significant disagreement. The reports in the two categories indicating disagreement were reviewed and reclassified by a consensus of three university-based neuroradiologists. RESULTS: Agreement between the initial interpretation by the general radiologist and the final interpretation by the neuroradiologist was found in 95% of the CT scans. The interpretations were judged to show insignificant disagreement in 3% (23/716) of the scans and to show significant disagreement in 2% (16/716). Of the 16 significant errors, five were false-positive findings and 11 were false-negative findings. Forty-seven CT scans depicted significant or active disease, and in 11 (23%) of these scans, the final report differed significantly from the preliminary interpretation. Three patients had pituitary masses, none of which had been described on the preliminary interpretation. CONCLUSION: The rate of significant discordance between board-certified on-call general radiologists and neuroradiologists in the interpretation of emergency CT scans was 2%, which was comparable to previously published reports of residents' performance. The pituitary gland may be a blind spot, and additional attention should be focused on this area.     

Influence of availability of clinical history on detection of early stroke using unenhanced CT and diffusion-weighted MR imaging

OBJECTIVE: The radiologic diagnosis of stroke requires accurate detection and appropriate interpretation of relevant imaging findings; both detection and interpretation may be influenced by knowledge of the patient's presentation. In our study, we evaluated the effect of the availability of clinical history on the sensitivity for stroke detection using unenhanced CT and diffusion-weighted MR imaging. MATERIALS AND METHODS: The records of 733 consecutive patients with a clinically based admission diagnosis of early stroke were reviewed. Among the criteria for inclusion in our study were the availability of an unenhanced CT scan (561 cases) or diffusion-weighted MR imaging examination (409 cases) obtained at admission and a discharge diagnosis indicating whether a patient had actually had a stroke. The radiology requisition forms, available at the time of image interpretation, were classified as either indicating or not indicating a clinical suspicion of early stroke. Sensitivity, specificity, and accuracy of stroke detection were computed, stratified by the presence or absence of an available history indicating suspicion of stroke. Results were compared using the Fisher's exact two-tailed test. RESULTS: Unenhanced CT sensitivity was 52% (specificity, 95%) for the suspicion-of-stroke group and 38% (specificity, 89%) for the no-suspicion-of-stroke group (p = 0.008). Diffusion-weighted MR imaging sensitivity was 95% (specificity, 94%) for the suspicion-of-stroke group and 94% (specificity, 98%) for the no-suspicion-of-stroke group (p = 0.822). CONCLUSION: Availability of a clinical history indicating that early stroke is suspected significantly improves the sensitivity for detecting strokes on unenhanced CT without reducing specificity. In contradistinction, the availability of such a history did not significantly improve the sensitivity for detecting stroke using diffusion-weighted MR imaging. Whenever possible, relevant clinical history should be made available to physicians interpreting emergency CT scans of the head.     

Preliminary interpretations of after-hours CT and sonography by radiology residents versus final interpretations by body imaging radiologists at a level 1 trauma center

OBJECTIVE: At many academic institutions, preliminary interpretations of CT scans and sonograms obtained after regular hours of operation are performed by radiology residents, with attending radiologists reviewing the interpretations the next morning. We sought to determine the rate of discrepancy between residents' interpretations of imaging studies and the final interpretations performed by an attending body imaging radiologist as well as any resulting clinical consequences stemming from the discrepancies. Therefore, we reviewed 928 CT and sonographic images that had been obtained after hours at a level 1 trauma center during a 6-month period. MATERIALS AND METHODS: Any discrepancies between the preliminary and final interpretations were judged as either major (i.e., necessitating an urgent change in treatment) or minor errors. We conducted patient follow-up via a retrospective review of the medical charts to determine whether any of the discrepancies led to additional imaging, an increase in patient morbidity, an extension of a hospital stay, or a change in treatment. RESULTS: The overall discrepancy rate in interpretations rendered by the residents and those performed by the attending radiologist was 3.8%, with most of these discrepancies (86%) judged to be minor. If we combined the data for body CT scans and sonograms, the rate of minor discrepancies was 3.2%, and the rate of major discrepancies was 0.5%. If we considered only body CT data in the evaluation, the overall discrepancy rate increased to 6.4%, with a 5.4% rate of minor discrepancies and a 1.0% rate of major discrepancies. CONCLUSION: Our evaluation of discrepancy rates was unusual in that we included interpretations of sonograms, on which residents and the attending radiologist had a higher rate of agreement (99.5%). Because of the high agreement in the interpretation of sonograms, the overall discrepancy rate was 3.8%. However, if only body CT scan interpretations were evaluated, our results were closer to the rates reported in previously published studies. Major discrepancies led to a change in patient treatment but did not lead to any increase in patient morbidity or to any quantifiable increase in the length of the hospital stay.     

Radiology resident interpretations of on-call imaging studies: the incidence of major discrepancies

RATIONALE AND OBJECTIVES: To determine the incidence of radiology resident preliminary interpretation errors for plain film, body computed tomography, and neuroradiology (neuro)computed tomographic examinations read on call. MATERIALS AND METHODS: We retrospectively reviewed the data in a prospectively acquired resident quality assurance (QA) database dating between January 2000 and March 2007. The database comprises all imaging studies initially interpreted by an on-call resident and later reviewed by a board-certified attending radiologist who determined the level of discrepancy between the two interpretations according to a graded scale from 0 (no discrepancy) to 3 (major discrepancy). We reviewed the data with respect to resident training level, imaging modality, and variance level. Statistical analysis was performed with chi(2) test, alpha = 0.05. We compared our results with other published series studying resident and attending accuracy. RESULTS: A total of 141,381 cases were entered into the database during the review period. Of all examinations, 95.7% had zero variance, 3.3% minor variance, and 1.0% major variance. There was a slight, statistically significant increase in overall accuracy with increased resident year from 95.4% of examinations read by first-year residents (R1s) to 96.1% by fourth-year resident (R4s) (P < .0001). Overall percentages of exams with major discrepancies were 1.0% for R1s, 1.1% for second-year residents, 1.0% for third-year residents, and 0.98% for R4s. CONCLUSIONS: The majority of preliminary resident interpretations are highly accurate. The incidence of major discrepancies is extremely low and similar, even with R1s, to that of attending radiologists published in other studies. A slight, statistically significant decrease in the error rate is detectable as residents gain experience throughout the 4 years of residency.     

Nonenhanced limited CT in children suspected of having appendicitis: prospective comparison of attending and resident interpretations.

PURPOSE: To prospectively compare resident and attending radiologic interpretations of nonenhanced limited computed tomographic (CT) scans obtained in children suspected of having appendicitis. MATERIALS AND METHODS: Seventy-five consecutive children underwent nonenhanced limited CT for suspected appendicitis. The scans were prospectively interpreted by a resident and an attending radiologist, each unaware of the other's interpretation. The probability that the findings indicated a diagnosis of appendicitis, level of certainty in the interpretation, and presence of an alternate diagnosis were statistically analyzed. RESULTS: Nineteen children (25%) had appendicitis. The area under the receiver operating characteristic curve was not significantly different between residents (0.97 +/- 0.02) and attendings (0.95 +/- 0.04). The percentage agreement between residents and attendings was 91% (kappa = 0.73 +/- 0.095). The average level of certainty tended to be higher for attendings (93% +/- 15) than residents (89% +/- 12). The sensitivity, specificity, and accuracy of resident interpretations were 63%, 96%, and 88%, respectively, compared with those of attending interpretations--95%, 98%, and 97%, respectively. Residents and attendings noted alternate diagnoses in 30% of children without appendicitis. CONCLUSION: A high level of agreement exists between resident and attending radiologists in the interpretation of nonenhanced limited CT scans in children suspected of having appendicitis. Residents, however, tend to be less confident in their interpretations.     

Accuracy of outside radiologists’ reports of computed tomography exams of emergently transferred patients

Purpose

Growing numbers of patient with advanced imaging being transferred to trauma centers has resulted in increased numbers of outside CT scans received at trauma centers. This study examines the degree of agreement between community radiologists’ interpretations of the CT scans of transferred patients and trauma center radiologists’ reinterpretation.

Methods

All CT scans of emergency transfer patients received over a 1 month period were reviewed by an emergency radiologist. Patients were classified as trauma or non-trauma and exams as neuro or non-neuro. Interpretive discrepancies between the emergency radiologist and community radiologist were classified as minor, moderate, or major. Major discrepancies were confirmed by review of a second emergency radiologist. Discrepancy rates were calculated on a per-patient and per exam basis.

Results

Six hundred twenty-seven CT scans of 326 patients were reviewed. Major discrepancies were encountered in 52 (16.0%, 95% CI 12.2–20.5) patients and 53 exams (8.5%, 95% CI 6.5–10.5). These were discovered in 46 trauma patients (21.6%, 95% CI 16.4–27.9) compared to six non-trauma patients (5.3%, 95% CI 2.2–11.7) (P?<?0.001). A significant difference in the major discrepancy rate was also found between non-neuro and neuro exams (12.4 vs 3.3%, respectively, P?<?0.001), primarily due to discrepancies in trauma patients, rather than non-trauma patients.

Conclusions

Potentially management-changing interpretive changes affected 16% of transferred patients and 8.5% of CT exams over a 1 month period. Trauma center reinterpretations of community hospital CT scans of transferred patients provide valuable additional information to the clinical services caring for critically ill patients.

     

Significant on-call misses by radiology residents interpreting computed tomographic studies: Perception versus cognition

The purpose of this study was to evaluate the etiology of significant false-negative computed tomographic (CT) interpretations by radiology residents on-call. Over a 1-year period, significant on-call false-negative CT interpretations were analyzed to determine whether errors were perceptual (i.e., the resident did not see the finding or findings) or cognitive (i.e., the resident did not recognize the implications or misinterpreted a finding or findings). Significant misses were defined as errors that delayed surgical treatment or misdirected management in a potentially life-threatening manner.A total of 12 significant false-negative interpretations occurred over a 1-year period. All head CT misses (extraaxial hemorrhage, pneumocephalus, contusion, subarachnoid hemorrhage due to ruptured aneurysm) were perceptual errors. Misses on thoracic, abdominal, and pelvic CT scans (2 abscesses, abdominal aortic aneurysm rupture, superior vena cava perforation due to catheter placement, ischemic bowel, liver laceration, hypoperfusion syndrome, appendicitis) were mixed (4 cognitive and 4 perceptual errors).Since the diagnostic possibilities of emergency head CT scans are limited, residents missed only subtle, perceptual manifestations and had little difficulty interpreting findings when they were correctly recognized. The gamut of diagnostic possibilities in the thorax, abdomen, and pelvis was more challenging to residents on-call; errors in both perception and interpretation arose with equal frequency, and the significant error rate was higher than that for head CT interpretation. Junior residents, who make most of the significant on-call errors, commonly feel overwhelmed in attempting to assimilate the knowledge required to take call. Prepartion needs to be extensive, yet it should be focused on areas that will engender optimal impact on after-hours performance. When preparing residents to interpret on-call CT studies, perceptual manifestations of neuroradiology should be emphasized, whereas a more comprehensive approach to thoracic, abdominal, and pelvic disorders needs to be stressed.Presented at the 8th Annual Meeting of the American Society of Emergency Radiology, New Orleans, March 20, 1997     

Resident Interpretation of Emergency CT Scans in the Evaluation of Acute Appendicitis

PURPOSE: Radiology resident interpretation of computed tomographic (CT) scans at academic institutions often guides management of cases of suspected acute appendicitis in the emergency department. The purpose of this study was to compare resident and faculty interpretation of CT scans obtained for acute appendicitis. MATERIALS AND METHODS: From December 16, 1999, to July 13, 2000, CT was performed in 103 consecutive patients between the hours of 9:00 PM and 8:00 AM who were suspected of having acute appendicitis. The authors compared the residents' preliminary written interpretations with both the final reports written by the faculty and the surgical findings. The faculty interpreting the CT scans were aware of resident interpretations but were not aware that a study was being conducted. RESULTS: The final faculty interpretation and the preliminary resident interpretation were identical in 96 of the 103 patients (93%; 95% confidence interval: 87.8%, 97.2%). In only one patient was a scan originally interpreted as negative interpreted as positive by the faculty member. Clinically, the patient did not have acute appendicitis, and surgery was not perforrmed. CONCLUSION: In the diagnosis of acute appendicitis, image interpretations made by adequately trained radiology residents can be expected to closely match those of the radiology faculty, and the practice of after-hours interpretation of such studies by radiology residents is safe.     

The iPad as a mobile device for CT display and interpretation: diagnostic accuracy for identification of pulmonary embolism

Recent software developments enable interactive, real-time axial, 2D and 3D CT display on an iPad by cloud computing from a server for remote rendering. The purpose of this study was to compare radiologists' interpretative performance on the iPad to interpretation on the conventional picture archive and communication system (PACS). Fifty de-identified contrast-enhanced CT exams performed for suspected pulmonary embolism were compiled as an educational tool to prepare our residents for night call. Two junior radiology attendings blindly interpreted the cases twice, one reader used the PACS first, and the other interpreted on the iPad first. After an interval of at least 2 weeks, the cases were reinterpreted in different order using the other display technique. Sensitivity, specificity, and accuracy for identification of pulmonary embolism were compared for each interpretation method. Pulmonary embolism was present in 25 patients, ranging from main pulmonary artery to subsegmental thrombi. Both readers interpreted 98 % of cases correctly regardless of display platform. There was no significant difference in sensitivity (98 vs 100 %, p?=?1.0), specificity (98 vs 96 %, p?=?1.0), or accuracy (98 vs 98 %, p?=?1.0) for interpretation with the iPad vs the PACS, respectively. CT interpretation on an iPad enabled accurate identification of pulmonary embolism, equivalent to display on the PACS. This mobile device has the potential to expand radiologists' availability for consultation and expedite emergency patient management.     

Intracranial calcifications in childhood medulloblastoma: relation to nevoid basal cell carcinoma syndrome

BACKGROUND AND PURPOSE: Medulloblastoma is one of the most common posterior fossa tumors to occur in children. Our purpose was to document the frequency, location, and time of occurrence of intracranial calcifications in cranial CT studies of children with medulloblastoma. METHODS: We retrospectively reviewed cranial CT studies of 56 patients diagnosed with medulloblastoma from 1983 through 1997 for the presence of intracranial calcifications. The findings were compared with 159 cranial CT studies of patients who were evaluated in the emergency department (control group). Thirty-two patients with medulloblastoma without shunts were compared with 118 patients from the control group without shunts. Similarly, 24 patients with medulloblastoma with shunts were compared with 41 patients from the control group with shunts. RESULTS: Overall, three (9%) patients with medulloblastoma without shunts, four (16%) patients with medulloblastoma with shunts, and four (10%) patients from the control group with shunts had falx calcification. Only the two children carrying the diagnoses of medulloblastoma and nevoid basal cell carcinoma syndrome, however, had calcification of the falx cerebri shown on the cranial CT scans obtained during the peridiagnostic period. Both were diagnosed with medulloblastoma before the age of 3 years and later developed jaw cysts and multiple basal cell carcinomas in the radiation field. CONCLUSION: Previous studies have shown that falx calcification is a major component of nevoid basal cell carcinoma syndrome. Our two cases illustrate the importance of considering the diagnosis of nevoid basal cell carcinoma syndrome when falx calcification is present in young patients with medulloblastoma. If the concomitant diagnosis of nevoid basal cell carcinoma syndrome is made, alternative types of therapy should be sought to minimize radiation therapy sequelae.     

Practical selection criteria for unenhanced cranial CT in patients with acute headache

We studied clinical predictors of cranial computed tomography (CT) abnormalities in patients with acute or acutely worsened headache. Data were collected from chart review of 333 consecutive patients presenting to an emergency department and who were clinically selected for cranial CT. Patients with a positive neurologic examination were at 10.7 times greater risk for a positive CT than the rest of the sample (p<1.5 – 10⁻¹⁰). Using only neurologic examination to select patients for CT would have missed 30.3% of the positive scans. The amnesia, depressed sensorium, and hypertension variables had CT yields approximating 10% or greater even in the presence of a negative neurologic examination. Together with a positive neurologic examination, these variables detected 87.9% of the patients in this sample with positive scans; their absence had a negative predictive value of 98.0%. Of the four patients with positive scans who would have been missed using this strategy, one was discharged directly from the emergency department anyway and the other three developed positive neurologic examinations within 24 hours. One died of causes unrelated to the intracranial pathology. Positive neurologic examination, hypertension, history of amnesia, or a depressed sensorium provide reasonable initial guidelines to select for CT patients with an acute headache.     

Lung cancers missed at low-dose helical CT screening in a general population: comparison of clinical,histopathologic, and imaging findings

PURPOSE: To compare clinical, histopathologic, and imaging features of lung cancers missed at low-radiation-dose helical computed tomography (CT). MATERIALS AND METHODS: Eighty-three primary lung cancers were found during an annual low-dose CT screening program and confirmed histopathologically at either surgery or biopsy. Thirty-two of these lung cancers were missed on 39 CT scans: on 23 scans owing to detection errors and on 16 owing to interpretation errors. The clinical characteristics, CT features, and histopathologic findings of these missed lung cancers were correlated. RESULTS: All missed cancers were intrapulmonary, and 28 (88%) were stage IA. All 20 detection errors occurred in cases of adenocarcinoma, 17 (85%) of which were well-differentiated tumors and 11 (55%) of which were in nonsmoking women. The mean size of cancers missed owing to detection error, 9.8 mm, was smaller than that of cancers missed owing to interpretation error, 15.9 mm (P <.001). In the detection error group, the percentages of nodules with ground-glass opacity (91%) or judged to be subtle (91%) were greater than those of nodules in the interpretation error group (38% and 25%, respectively) (P <.001). In the detection error group, 83% (19/23) of cancers were overlapped with, obscured by, or similar in appearance to normal structures such as pulmonary vessels. On 14 of the 16 CT scans with which there were interpretation errors, the CT findings mimicked benign disease, and the patients also had underlying lung disease, such as tuberculosis, emphysema, or lung fibrosis. CONCLUSION: The lung cancers missed at low-dose CT screening in this series generally were very subtle and appeared as small faint nodules, overlapping normal structures, or opacities in a complex background of other disease.     

Suspected acute appendicitis: nonenhanced helical CT in 300 consecutive patients.

PURPOSE: To determine the accuracy of helical computed tomography (CT) without the oral, intravenous, or rectal administration of contrast material in confirming suspected acute appendicitis. MATERIALS AND METHODS: Three hundred consecutive patients referred from the departments of surgery and emergency medicine were examined for suspected acute appendicitis by using thin-section nonenhanced helical CT. All transverse CT scans were obtained in a single breath hold from the upper abdomen (T12 vertebra) to the pubic symphysis with 5-mm collimation and a pitch of 1.6. All scans were obtained without oral, intravenous, or rectal contrast material. Criteria for diagnosis of acute appendicitis included an enlarged appendix (> 6 mm) and periappendiceal inflammation. CT diagnoses were recorded prospectively. Final diagnoses were established with the results of surgical or clinical follow-up or both. RESULTS: There were 110 true-positive diagnoses, 181 true-negative diagnoses (63 of which were an alternative diagnosis correctly established prospectively), five false-negative diagnoses, and four false-positive diagnoses, which yielded a sensitivity of 96%, a specificity of 99%, and an accuracy of 97%. CONCLUSION: Nonenhanced helical CT is a highly accurate technique for diagnosing or excluding acute appendicitis. Developing experience with the technique and understanding the subtleties of interpretation can further improve diagnostic accuracy.     

Peripancreatic vascular abnormalities complicating acute pancreatitis: contrast-enhanced helical CT findings

OBJECTIVE: To determine the prevalence and morphologic helical computed tomography (CT) features of peripancreatic vascular abnormalities in patients with acute pancreatic inflammatory disease in correlation with the severity of the pancreatitis. MATERIALS AND METHODS: One hundred and fifty-nine contrast-enhanced helical CT scans of 100 consecutive patients with acute pancreatitis were retrospectively and independently reviewed by three observers. CT scans were scored using the CT severity index (CTSI): pancreatitis was graded as mild (0-2 points), moderate (3-6 points), and severe (7-10 points). Interobserver agreement for both the CT severity index and the presence of peripancreatic vascular abnormalities was calculated (K-statistic). Correlation between the prevalence of complications and the degree of pancreatitis was estimated using Fisher's exact test. RESULTS: The severity of pancreatitis was graded as mild (n = 59 scans), moderate (n = 82 scans), and severe (n = 18 scans). Venous abnormalities detected included splenic vein (SV) thrombosis (31 scans, 19 patients), superior mesenteric vein (SMV) thrombosis (20 scans, 14 patients), and portal vein (PV) thrombosis (17 scans, 13 patients). Arterial hemorrhage occurred in five patients (6 scans). In our series, no cases of arterial pseudoaneurysm formation were detected. The interobserver agreement range for scoring the degree of pancreatitis and the overall presence of major vascular abnormalities was 75.5-79.2 and 86.2-98.8%, respectively. The presence of the vascular abnormalities in correlation with the severity of pancreatitis was variable. CONCLUSION: Vascular abnormalities are relatively common CT findings in association with acute pancreatitis. The CT severity index is insufficiently accurate in predicting some of these complications since no statistically significant correlation between their prevalence and the severity of pancreatitis could be established.