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James T Rhea

Publications and source records attributed to James T Rhea.

At least 19 recordsLinked to original sources
PubMed2006

Suspected aortic dissection and other aortic disorders: multi-detector row CT in 373 cases in the emergency setting.

PURPOSE: To retrospectively review the authors' experience with multi-detector row computed tomography (CT) for detection of aortic dissection in the emergency setting. MATERIALS AND METHODS: The investigation was institutional review board approved, did not require informed patient consent, and was HIPAA compliant. In 373 clinical evaluations in the emergency setting, 365 patients suspected of having aortic dissection and/or other aortic disorders underwent multidetector CT. Criteria for acute aortic disorder were confirmed by using surgical and pathologic diagnoses or findings at clinical follow-up and any subsequent imaging as the reference standard. Positive cases were characterized according to type of disorder interpreted. Resulting sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were calculated by using two-way contingency tables. All cases found to be negative for acute aortic disorders were grouped according to alternative CT findings. RESULTS: Sixty-seven (18.0%) of the 373 cases were interpreted as positive for acute aortic disorder. One hundred twelve acute aortic disorders were identified in these 67 cases: 23 acute aortic dissections, 14 acute aortic intramural hematomas, 20 acute penetrating aortic ulcers, 44 new or enlarging aortic aneurysms, and 11 acute aortic ruptures. Three hundred five (81.8%) cases were interpreted as negative for acute aortic disorder. In 48 negative cases, multidetector CT depicted alternative findings that accounted for the clinical presentation. Of these, three included both acute aortic disorders and alternative findings, and 45 included only alternative findings. One (0.3%) case was indeterminate for acute aortic disorder. Overall, 112 findings were interpreted as positive for acute aortic disorder, an alternative finding, or both at CT. No interpretations were false-positive, one was false-negative, 67 were true-positive, and 304 were true-negative. Sensitivity, specificity, PPV, NPV, and accuracy were 99% (67 of 68), 100% (304 of 304), 100% (67 of 67), 99.7% (304 of 305), and 99.5% (371 of 373), respectively. CONCLUSION: The positivity rate for acute aortic dissection or other acute aortic disorder in 373 cases examined at multi-detector row CT was 18.0%.

Acute Disease↗
PubMed2005

How to simplify the CT diagnosis of Le Fort fractures.

OBJECTIVE: The numerous components seen in the Le Fort fractures make classification difficult. Our objective is to simplify the task of classifying Le Fort fractures. CONCLUSION: Each of the Le Fort fractures has at least one unique component that is easily recognizable: I, the anterolateral margin of the nasal fossa; II, the inferior orbital rim; and III, the zygomatic arch. Classification of the Le Fort fractures is simplified by using these unique components to establish a tentative classification that is then confirmed.

Diagnosis, Differential↗
PubMed2005

The status of appendiceal CT in an urban medical center 5 years after its introduction: experience with 753 patients.

OBJECTIVE: Appendiceal CT was introduced at our hospital in 1996 and now is used in most patients. The use of appendiceal CT has generated controversy and mixed results in various investigations. Our purpose was to determine the percentage of patients for whom CT was performed, incidence of appendicitis, accuracy of CT, percentage of equivocal interpretations, and negative appendectomy rates for those patients who did and did not undergo CT. MATERIALS AND METHODS: Patient records from 2001 that included clinical or CT preoperative examination were analyzed, with follow-up through 2003. Patient age and sex, clinical presentation, CT techniques, CT interpretations, operative reports, pathology reports, and patient disposition were determined. Final diagnoses were provided by pathologic criteria, patient follow-up, or patient survey. Statistical analysis included Fisher's exact test and receiver operating characteristic (ROC) curves. RESULTS: Of 753 patients, 663 (88%) were examined on CT for suspected appendicitis and 90 had an appendectomy without undergoing CT. The incidence of appendicitis in the patients who underwent CT was 39.2%. The sensitivity and specificity of CT were 99% and 95%, respectively; the area under the ROC curve was 0.9896; and the percentage of equivocal CT interpretations was 3.3%. The false-negative appendectomy rates were 3.0% and 5.6% for patients with and without CT, respectively (for all patients, p = 0.326; for female pediatric patients, p = 0.030). CONCLUSION: Five years ago, the negative appendectomy rate dropped from 20% to 7%, and it is now 3.0%. The incidence of appendicitis in patients who are examined on CT is stable compared with similar cohorts from prior investigations. Patients who do not undergo CT also have a low negative appendectomy rate, but this relatively small group is selected on the basis of a convincing clinical presentation. Female pediatric patients likely would have a lower negative appendectomy rate with greater use of CT.

Acute Disease↗
PubMed2004

Controversies in emergency radiology. CT versus ultrasound in the evaluation of blunt abdominal trauma.

There has been controversy regarding ultrasonography (US) versus CT in blunt abdominal trauma (BAT). Each modality has its strengths and weaknesses. US is fast and allows resuscitative efforts to proceed while the patient is being scanned. However, the sensitivity of US is inferior to that of CT, and there is user variability. CT is better at determining the extent, type, and grade of injury, resulting in a more tailored therapeutic plan and safe conservative management of many patients. However, CT involves ionizing radiation, cannot be performed portably, and requires only visual monitoring while scanning. Given each modality's strengths and weaknesses we conclude that CT is the preferred examination when the BAT patient is stable or moderately stable, enough to be taken to CT. If a BAT patient is unstable, US is beneficial in screening for certain injuries or large hemoperitoneum prior to an exploratory laparotomy.

Abdominal Injuries↗
PubMed2004

CT of nontraumatic abdominal fluid collections after initial fluid resuscitation of patients with major burns.

OBJECTIVE: The purpose of this study was to describe the presence and CT distribution of nontraumatic fluid collections and edema in the abdomen and pelvis after initial fluid resuscitation of patients with major (>/==" BORDER="0"> 25% total body surface area) thermal burns. CONCLUSION: Awareness of the presence and expected CT distribution of nontraumatic fluid after initial fluid resuscitation in patients with major burns can assist the radiologist in differentiating such collections from those caused by mechanical trauma.

Abdomen↗
PubMed2004

Trends in the use of CT and radiography in the evaluation of facial trauma, 1992-2002: implications for current costs.

OBJECTIVE: CT has replaced conventional radiography of the face in many trauma centers. Concern exists that increased costs are associated with increased use of CT. Our goal was to compare the amount of CT and radiography performed for facial trauma at a level 1 trauma center in 1992 and in 2002 and to determine hospital costs for the imaging of these patients. MATERIALS AND METHODS: The changes in volume and types of facial imaging examinations were determined comparing 1992 and 2002. Hospital costs of different imaging examinations were determined for 2002. Current costs of imaging facial trauma were compared with what 2002 costs would have been if the practice pattern in 1992 had continued. RESULTS: In 1992, 890 patients were evaluated for facial trauma. Six hundred seventy-one had only radiography, 153 only CT of the face, and 66 both CT and radiography. In 2002, 828 patients were evaluated. Five hundred eighty-four patients had only CT of the face; 228, only radiography; and 16, both CT and radiography. The number of facial imaging examinations per patient in 1992 and 2002 was 1.23 and 1.03, respectively. The 2002 hospital cost of a facial CT examination was $121 and of a facial radiography series was $154. Using CT instead of radiography for evaluating facial injury resulted in an overall cost savings of 22% per patient in 2002. CONCLUSION: The availability of CT has not resulted in increased use of facial imaging. The increased use of CT from 1992 to 2002 results in decreased current costs for the hospital.

Adolescent↗
PubMed2004

Comparison of image quality between conventional and low-dose nonenhanced head CT.

BACKGROUND AND PURPOSE: Increasing use of CT for evaluating neurologic disease may expose patients to considerable levels of ionizing radiation. We compared the image quality of low-mAs head CT scans with that of conventional nonenhanced scans. METHODS: Conventional head CT scans were obtained in 20 patients (all >65 years with history of non-CNS malignancy) by using a multidetector technique: 170 mA and 1-second scanning time (ie, 170 mAs), 140 kVp, table speed of 7.5 mm per rotation, pitch of 0.75, section thickness of 5 mm, and field of view of 25 mm. A limited volume helical data acquisition covering four 5-mm-thick images was obtained by using 90 mAs but otherwise the same parameters. Three neuroradiologists visually rated the resulting images for quality in a blinded comparison. Representative 1- to 4-mm(2) regions of interest were chosen in gray matter and white matter locations. Conspicuity and the contrast-to-noise ratio were analyzed. Statistical comparisons were done by using the Student t test. RESULTS: Mean gray matter conspicuity was not significantly different between the 170- and 90-mAs groups (0.39 +/- 0.19 vs 0.41 +/- 0.03, P =.32). Mean gray matter contrast-to-noise ratio was approximately 22% higher with 170 mAs than with 90 mAs (1.77 +/- 0.52 vs 1.39 +/- 0.38, P =.005). All 90-mAs images were rated as having slightly greater image noise than the 170-mAs scans but with sufficient perceived resolution. CONCLUSION: Although 90-mAs head CT images were moderately noisier than 170-mAs images, they were rated as having acceptable diagnostic quality.

Aged↗
PubMed2003

The jet ski open-book pelvic fracture: diagnosis with multidetector CT.

A 10-year-old girl sustained a traumatic open-book pelvic fracture from a straddle injury in a jet ski accident. Plain films and computed tomography both demonstrated diastasis of the symphysis pubis and bilateral widening of the sacroiliac joints. The open-book fracture resulted from the patient's striking the steering column of the watercraft during a deceleration accident. The unusual cause of this injury is of clinical interest because with increasing popularity of personal watercraft and changes in the design of these vehicles, the incidence and prevalence of this type of injury may increase in the future.

Journal Article↗
PubMed2003

Transportable versus fixed platform CT scanners: comparison of costs.

PURPOSE: To compare the aggregate hospital technical costs of a transportable computed tomographic (CT) scanner used to image patients in an intensive care unit with those of a fixed platform CT scanner in the radiology department. MATERIALS AND METHODS: Direct fixed costs (ie, machine and service contract costs) and direct variable costs (ie, personnel costs) were calculated. Indirect costs, including space costs and departmental overhead, were calculated. Total costs were calculated as the sum of indirect, direct fixed, and direct variable costs. Personnel costs were calculated from time-motion analyses involving 95 patients who underwent brain CT with either a transportable (n = 51) or a fixed platform (n = 44) CT scanner. Costs per examination were calculated by using both low- and high-examination-volume models and compared with use of the Wilcoxon rank sum test. RESULTS: The total cost per examination for the transportable scanner ranged from 108.98 dollars to 167.20 dollars for the high- and low-volume models. Total cost per examination for the fixed platform scanner ranged from 75.24 dollars to 112.39 dollars for the high- and low-volume models. For the transportable scanner, direct fixed, variable, and overhead costs were 87.05 dollars, 70.73 dollars, and 9.42 dollars per examination, respectively, with the low-volume model. The corresponding costs for the fixed platform scanner were 46.66 dollars, 55.69 dollars, and 10.04 dollars, respectively. CONCLUSION: The technical cost of using an in-hospital transportable CT scanner is higher than that of using a fixed platform scanner.

Costs and Cost Analysis↗
PubMed2003

Multi-detector row CT: radiation dose characteristics.

PURPOSE: To determine the dose characteristics of multi-detector row computed tomography (CT) and to provide tabulated dose values and rules of thumb that assist in minimizing the radiation dose at multi-detector row CT. MATERIALS AND METHODS: Weighted CT dose index (CTDI100w) values were obtained from three multi-detector row CT scanners (LightSpeed; GE Medical Systems, Milwaukee, Wis) for both head and body CT modes by using standard CT-dose phantoms. The CTDI100w was determined as a function of x-ray tube voltage (80, 100, 120, 140 kVp), tube current (range, 50-380 mA), tube rotation time (0.5-4.0 seconds), radiation profile width (RPW) (5, 10, 15, 20 mm), and acquisition mode (helical high-quality and high-speed modes and axial one-, two-, and four-section modes). Statistical regression was performed to characterize the relationships between CTDI100w and various technique factors. RESULTS: The CTDI100w (milligray) increased linearly with tube current: in head mode, CTDI100w = (0.391 mGy/mA +/- 0.004) x tube current (milliampere) (r2 = 0.999); in body mode, CTDI100w = (0.162 mGy/mA +/- 0.002) x tube current (milliampere) (r2 = 0.999). The CTDI100w increased linearly with rotation time: in head mode, CTDI100w = (34.7 mGy/sec +/- 0.2) x rotation time (seconds) (r2 = 1.0); in body mode, CTDI100w = (13.957 mGy/sec +/- 0.005) x rotation time (seconds) (r2 = 1.0). The relationship of normalized CTDI100w (milligrays per 100 mAs) with tube voltage followed a power law: in head mode, CTDI100w = (0.00016 mGy/100 mAs. kVp +/- 0.00007) x (tube voltage)(2.5+/-0.1) (r2 = 0.997); in body mode, CTDI100w = (0.000012 mGy/100 mAs. kVp +/- 0.000007) x (tube voltage)(2.8+/-0.1) (r2 = 0.996). In all scanning modes, CTDI100w decreased when RPW increased. CTDI100w was 10% higher in head mode and 13% lower in body mode compared with the value suggested by the manufacturer, which is displayed at the scanner console. When deposited power exceeded 24 kW, CTDI100w increased by 10% as a result of use of the large focal spot. CONCLUSION: The authors provide a set of tables of radiation dose as a function of imaging protocol to facilitate implementation of radiation dose-efficient studies.

Head↗
PubMed2003

Radiation dose is reduced with a single-pass whole-body multi-detector row CT trauma protocol compared with a conventional segmented method: initial experience.

Radiation dose data were collected from a calibrated multi-detector row computed tomographic (CT) scanner during trauma CT. One protocol (used with 10 case subjects) involved a single-pass continuous whole-body acquisition from cranial vertex to symphysis pubis, while the other, conventional protocol (used with 10 control subjects) involved scouting and scanning body segments (head, cervical spine, chest, abdomen, and pelvis) individually. Technical factors were kept constant within each body segment for the single-pass and the segmented protocols. Statistics included univariate analysis, two-tailed t testing to evaluate statistical significance of the summary statistic, and power and subject population contingency tables. The mean dose length product (DLP) with the single-pass protocol was 17% lower than the sum of the DLPs of each of the individual body segment scans (P <.001). Analysis of power and subject population by using a difference in mean of 500 mGy. cm and an alpha of.05 revealed a (1-beta) of higher than 0.90 for a sample of 10 patients. Thus, a whole-body single-pass trauma protocol, compared with a typical segmented acquisition protocol matched for imaging technique, resulted in reduced total radiation dose. The reduction in radiation dose is thought to represent a reduction in redundant imaging at overlap zones between body segments scanned in the segmental protocol but not in the continuous acquisition.

Humans↗
PubMed2003

Cerebral fractional anisotropy score in trauma patients: a new indicator of white matter injury after trauma.

OBJECTIVE: Previous studies evaluating quantitative cerebral white matter diffusion anisotropy indexes have shown alteration in patients after trauma. To date, no clinically applicable scale exists by which to gauge and test the relevance of these findings. We propose the cerebral fractional anisotropy score in trauma (C-FAST) as an index of white matter injury, and we correlate C-FAST with several predictor and outcome variables. MATERIALS AND METHODS: Fifteen patients were randomly selected from the trauma surgery service. Thirty control patients were randomly selected from the emergency department. All patients were subjected to MRI evaluation, including a diffusion-weighted sequence. Data extracted from the record of each subject included Glasgow Coma Scale, revised trauma score, Abbreviated Injury Scale, initial head CT results, patient disposition, length of hospital stay, and length of stay in intensive care unit. Region of interest measurements were made in fractional anisotropy maps in each of 12 white matter regions. Univariate statistics and a two-tailed t test were performed on the raw fractional anisotropy data. Data were then dichotomized using thresholds from univariate statistics. A C-FAST score was devised from the dichotomized data. Logistic regression analyses were performed among the C-FAST, outcome, and predictor data. RESULTS: Good correlation was noted between the C-FAST and death, hospital stay greater than 10 days, and intensive care unit stay greater than 5 days. Correlation with discharge to rehabilitation facility was good when adjusted for age and sex. Glasgow Coma Scale, revised trauma score, and Abbreviated Injury Scale show good correlation as predictors of a critical C-FAST. CONCLUSION: The C-FAST is a promising index derived from MRI diffusion fractional anisotropy measurements that shows successful correlation with outcome and predictor variables. A larger investigation is needed to verify the validity and stability of the correlations.

Adult↗
PubMed2002

Is the screening portable pelvis film clinically useful in multiple trauma patients who will be examined by abdominopelvic CT? Experience with 397 patients.

The multiple trauma patient is usually initially imaged with a portable "trauma series" consisting of a lateral cervical spine film, a portable chest film, and a portable pelvis film (PPF). An investigation was performed to determine whether the screening PPF could be eliminated for multiple trauma patients being examined by abdominopelvic CT scan (APCT). A retrospective investigation analyzed all patients evaluated in our level I trauma center from 1 January to 31 December 2000 who were examined with a "trauma series" followed by an APCT scan within 8 h. The numbers and types of fractures diagnosed by PPF and by APCT were compared and correlated with clinical follow-up. Of 397 patients imaged by both PPF and APCT, 43 patients were diagnosed with 109 individual fractures by CT scan. The PPF did not detect 51 of the 109 individual fractures (47%) and failed to diagnose 9 of the 43 patients (21%) with a pelvic fracture. The PPF most often failed to detect sacral and iliac fractures. The four cases in which the PPF reported a fracture not listed in the APCT report were due to reporting errors or film artifacts. No soft tissue injuries were seen by PPF that were not also seen by APCT. We conclude that the screening PPF appears to be an unnecessary exam in multiple trauma patients about to be imaged by APCT scan.

Journal Article↗
PubMed2002

Lumbar fractures in adult blunt trauma: axial and single-slice helical abdominal and pelvic computed tomographic scans versus portable plain films.

BACKGROUND: Our hypothesis was that abdominal and pelvic computed tomographic (AP-CT) scans are equivalent to portable two-view plain films in detecting lumbar spine fractures in adults. Since many trauma patients often undergo AP-CT scanning to evaluate for possible intra-abdominal injuries, using the AP-CT scan to screen for lumbar fractures could make the trauma evaluation process more efficient. METHODS: The institutional trauma registry at a Level I trauma center was used to identify all blunt lumbar fractures during a 6-year period. Medical records were reviewed. RESULTS: A total of 7,216 adult blunt trauma patients were evaluated, and 115 patients were identified as having a lumbar fracture, for an incidence rate of 1.6%. Missed fracture rates were high for both AP-CT scans (23.2%, 13 of 56) and portable two-view films (12.7%, 14 of 110, = 0.08). Fifty-two patients had both AP-CT scans and plain films. In this group, AP-CT scans missed 23.1% (12 of 52) of the lumbar fractures and plain films missed 15.4% (8 of 52). However, the combination of the two diagnostic methods did not miss any fractures (0 of 52). The missed fractures required surgery or brace in 50% (7 of 14) patients who had fractures missed by plain films and 46% (6 of 13) patients whose fractures were missed by AP-CT scanning. CONCLUSION: Both AP-CT scans and plain films failed to diagnose significant lumbar fractures that required therapy. When screening for lumbar fractures, obtaining both AP-CT scans and portable two-view plain films may decrease missed lumbar fractures in blunt adult trauma.

Adult↗
PubMed2002

Frequency, sensitivity, and specificity of individual signs of diverticulitis on thin-section helical CT with colonic contrast material: experience with 312 cases.

OBJECTIVE: The aim of our study was to determine the frequency, sensitivity, and specificity of the individual signs of diverticulitis using helical CT with colonic contrast material. MATERIALS AND METHODS: Between March 1997 and September 1999, 312 patients with suspected diverticulitis were examined on helical CT using rectally administered colonic contrast material. CT scans that were positive for diverticulitis or indeterminate were rereviewed by two radiologists; CT interpretations were correlated with patients' clinical courses and surgical findings. RESULTS: One hundred fourteen (37%) of the 312 CT scans were interpreted as positive for diverticulitis; 192 scans (61%), as negative; six scans (2%), as indeterminate. Of the 114 scans that were positive for diverticulitis, 109 (96%; sensitivity 96%, specificity 91%) showed bowel wall thickening; 108 (95%; sensitivity 96%, specificity 90%), fat stranding; 104 (91%; sensitivity 91%, specificity 67%), diverticula; 57 (50%; sensitivity 50%, specificity 100%), fascial thickening; 51 (45%; sensitivity 45%, specificity 97%), free fluid; 49 (43%; sensitivity 43%, specificity 100%), inflamed diverticula; 34 (30%; sensitivity 30%, specificity 100%), free air; 18 (16%; sensitivity 16%, specificity 100%), "arrowhead" signs; nine (8%; sensitivity 8%, specificity 99%), abscesses; four (4%; sensitivity 4%, specificity 100%,), phlegmons; five (4%; sensitivity 4%, specificity 99%), intramural air; two (2%; sensitivity 2%, specificity 100%), intramural sinus tracts. Overall CT interpretation had a sensitivity of 99%, a specificity of 99%, a positive predictive value of 99%, a negative predictive value of 99%, and an overall accuracy of 99%. CONCLUSION: The two most frequent signs of diverticulitis were bowel wall thickening (96%) and fat stranding (95%). Less frequent but highly specific signs were fascial thickening (50%), free fluid (45%), and inflamed diverticula (43%).

Adult↗
PubMed2002

Clinical comparison of standard-dose and 50% reduced-dose abdominal CT: effect on image quality.

OBJECTIVE: We hypothesized that radiation doses for abdominal CT could be reduced by adjusting the dose for a patient's weight and cross-sectional abdominal dimensions, with the resultant scans still being of diagnostic quality. SUBJECTS AND METHODS: Using a multidetector CT scanner, we prospectively studied 39 patients who were 65 years and older who had a known history of cancer. After performing a diagnostic contrast-enhanced CT examination, we obtained four slices each (centered at the top of the right kidney) at a standard radiation dose (240-300 mA) and at a 50% reduced dose (120-150 mA) at a constant kilovoltage of 140. Scans were obtained during a single breath-hold, with a 2.5-mm detector configuration and a slice pitch of 6:1. Reconstructed slice thickness was 5 mm. In a blinded review, two radiologists rated the randomized CT scans for overall image quality and anatomic details of liver, spleen, adrenal glands, kidneys, pancreas, and abdominal wall, using a 5-point scale (1 = unacceptable, 2 = substandard, 3 = acceptable, 4 = above average, and 5 = superior). Patients' weight and abdominal circumference, area, and anteroposterior and transverse diameters were correlated with image quality of scans obtained at standard-dose and 50% reduced-dose CT. Statistical analysis of the data was performed using Wilcoxon's signed rank test. RESULTS: Overall, the image quality score was significantly higher (p < 0.005) on the scans obtained with standard-dose CT. No statistically significant difference in image quality was noted in the 50% reduced- and standard-dose CT scans in patients who weighed less than 180 lb, or 81 kg, (p > 0.05) and who had a transverse abdominal diameter of less than 34.5 cm (p > 0.05), an anteroposterior diameter of less than 28 cm (p > 0.05), a cross-sectional circumference of less than 105 cm (p > 0.05), and a cross-sectional area of less than 800 cm(2) (p > 0.05). Good interobserver agreement (p > 0.5) was found between the two reviewing radiologists. CONCLUSION: Abdominal CT scan quality appears to be acceptable even with a 50% reduction in radiation dose except in patients with large anthropometric measurements. A reduction in CT radiation dose is possible if the tube current is optimized for the patient's weight and abdominal dimensions.

Abdomen↗