Abdominopelvic Computed Tomography Examinations Research Articles

Opportunistic assessment of ischemic heart disease risk using abdominopelvic computed tomography and medical record data: a multimodal explainable artificial intelligence approach

Current risk scores using clinical risk factors for predicting ischemic heart disease (IHD) events—the leading cause of global mortality—have known limitations and may be improved by imaging biomarkers. While body composition (BC) imaging biomarkers derived from abdominopelvic computed tomography (CT) correlate with IHD risk, they are impractical to measure manually. Here, in a retrospective cohort of 8139 contrast-enhanced abdominopelvic CT examinations undergoing up to 5 years of follow-up, we developed multimodal opportunistic risk assessment models for IHD by automatically extracting BC features from abdominal CT images and integrating these with features from each patient’s electronic medical record (EMR). Our predictive methods match and, in some cases, outperform clinical risk scores currently used in IHD risk assessment. We provide clinical interpretability of our model using a new method of determining tissue-level contributions from CT along with weightings of EMR features contributing to IHD risk. We conclude that such a multimodal approach, which automatically integrates BC biomarkers and EMR data, can enhance IHD risk assessment and aid primary prevention efforts for IHD. To further promote research, we release the Opportunistic L3 Ischemic heart disease (OL3I) dataset, the first public multimodal dataset for opportunistic CT prediction of IHD.

Evaluation of organ and effective doses using anthropomorphic phantom: A comparison between experimental measurement and a commercial dose calculator

IntroductionThe aim of this study was to experimentally measure organ doses for computed tomography (CT) procedures using thermoluminescence dosimeters (TLDs) on a RANDO anthropomorphic phantom and verify the measured doses using CT-Expo software. MethodsThe phantom was irradiated using clinical CT scan protocols routinely used for specific procedures in the radiology department. Fifty TLD chips were used in this study. The scanning parameters (kVp, mA, s) used to scan the phantom were used as input parameters for CT-Expo dose estimations. ResultsThe TLD measured organ doses varied between 3.97 mGy for the esophagus and 56.22 mGy for the brain. High doses were recorded in the brain (37.80–56.22 mGy) and the eye lens (29.94–36.16 mGy). Comparing the organ dose measurements between TLD and CT-Expo, the maximum organ dose difference was obtained for the eye lens. A comparison between the two methods for the other organs were all less than 32 %. The effective doses from the TLD measurements for the head, chest, and abdominopelvic CT examinations were 2.78, 6.67, and 17 mSv, respectively and CT-Expo were 2.20, 10.30, and 16.70 mSv, respectively. ConclusionThe experimental and computational results are comparable, and the reliability of the TLD measurements and CT-Expo dose calculator has been proven. Implications for studyA reason for the difference in dose measurements between the two methods has been attributed to the dissimilarity in the organ position in the Rando anthropomorphic phantom and the standard mathematical phantom used by CT-Expo. The experimental and computational results have been found to be comparable.

The role of computed tomography in enterolith causing small bowel obstruction: A case series.

Intestinal obstruction caused by enteroliths is an uncommon medical condition. Timely detection of the presence of enteroliths and identification of their origin can guide clinical treatment. This study aimed to present the Computed Tomography (CT) features of enterolithic ileus confirmed by surgery in 7 patients. Seven patients with surgically confirmed enterolithic ileus who were admitted to our hospital between December 2013 and December 2022 were continuously enrolled, and an abdominopelvic CT examination was performed before surgery. The imaging characteristics were then analyzed. In the transition zone of all patients with intestinal obstruction, the sharply defined intraluminal masses were found. Three of them had gallstones and 4 had primary enteroliths. All 5 enteroliths in the 4 patients with primary enteroliths were in the proximal small intestine and were low-density with gas. Additionally, 3 gallstones were present in the distal small bowel, and calcifications were observed. Simultaneously, cholecystitis and secondary cholecystoduodenal fistula were observed in all 3 patients with gallstones. Compared to gallstones, primary enteroliths tend to be higher positioned, less dense, and accompanied by gas. CT examination is very important, as it allows accurate identification, location, diagnosis, and identification of complications of the different types of enteroliths to provide a basis for surgery.

Development of size-specific dose estimates for common computed tomography examinations: a study in Ghana

This study determined the size-specific dose estimate (SSDE) of computed tomography (CT) examinations and derived mathematical expressions for dose output estimation and optimization in a teaching hospital in Ghana. Demographic and scanner output indices, including CT dose index (CTDIvol) and dose length product for adult head, chest and abdominopelvic (ABP) CT examinations carried out at the hospital from 2018 to 2020, were retrieved from the picture archiving and communication system of the CT scanner machine. Other indices such as the antero-posterior diameter (D AP), lateral diameter (D L) and diagonal diameter (D dia) of the patients’ bodies were measured on the mid-slice axial image using a digital caliper. The effective diameter (D eff) was then calculated as the square root of the product of the D AP and D L. The SSDEs were calculated as the product of the CTDIvol and the size-specific conversion factors obtained from Report 204 of the American Association of Physicists in Medicine. Regression analyses were performed to find the relationship between SSDE and the various parameters to derive mathematical equations for the dose estimations. There were more female samples (n= 468, 56.3%) than male samples (n = 364, 43.7%) for each CT procedure. The SSDEs and size-specific diagnostic reference levels (SSDRLs) were: head (83.9 mGy; 86.9 mGy), chest (8.1 mGy; 8.7 mGy) and ABP (8.4 mGy; 9.2 mGy). The variations between CTDIvol and SSDEs for head (2.50%), chest (25.9%), and ABP (26.2%) showed an underestimation of radiation dose to patients, especially in chest and ABP examinations, if CTDIvol is used to report patient doses. The SSDEs of the chest and ABP CT examinations showed linear correlations with the CTDIvol. The estimated values could be used to optimize radiation doses in the CT facility. The SSDE and SSDRLs for head, chest and ABP CT examinations have been developed at a teaching hospital in Ghana. The SSDEs of chest and ABP examinations showed linear correlations with the CTDIvol and hence can be calculated using the mathematically derived equations in the study.

Establishment of local diagnostic reference levels for common adult CT examinations: a multicenter survey in Addis Ababa

BackgroundIn medical imaging, a computed tomography (CT) scanner is a major source of ionizing radiation. All medical radiation exposures should be justified and optimized to meet the clinical diagnosis. Thus, to avoid unnecessary radiation doses for patients, diagnostic reference levels (DRLs) have been used. The DRLs are used to identify unusually high radiation doses during CT procedures, which are not appropriate for the clinical diagnosis. It has been successfully implemented in Europe, Canada, Australia, the United States, several industrialized countries, and a few underdeveloped countries. The present study aimed to establish DRLs for the head, chest, and abdominopelvic (AP) CT procedures in Addis Ababa, Ethiopia.MethodsA pilot study identified the most frequent CT examinations in the city. At the time of the pilot, eighteen CT scan facilities were identified as having functioning CT scanners. Then, on nine CT facilities (50% of functional CT scanners), a prospective analysis of volume CT dose index (CTDIvol) and dose length product (DLP) was performed. We collected data for 838 adult patients’ head, chest, and AP CT examinations. SPSS version 25 was used to compute the median values of the DLP and CTDIvol dose indicators. The rounded 75th percentile of CTDIvol and DLP median values were used to define the DRLs. The results are compared to DRL data from the local, regional, and international levels.ResultThe proposed DRLs using CTDIvol (mGy) are 53, 13, and 16 for the head, chest, and AP examinations respectively, while the DLP (mGy.cm) for the respective examinations were 1210, 635, and 822 mGy.cm.ConclusionBaseline CT DRLs figures for the most frequently performed in Addis Ababa were provided. The discrepancies in dose between CT facilities and as well as between identical scanners suggests a large potential for dose optimization of examinations. This can be actually achieved through appropriate training of CT technologists and continuous dose audits.

CT features associated with underlying malignancy in patients with diagnosed mesenteric panniculitis

PurposeThe purpose of this study was to identify abdominal computed tomography (CT) features associated with underlying malignancy in patients with mesenteric panniculitis (MP). Materials and methodsThis single-institution retrospective longitudinal cohort study included patients with MP and a minimum 1-year abdominopelvic CT follow-up or 2-year clinical follow-up after initial abdominopelvic CT examination. Two radiologists, blinded to patients’ medical records, conjointly reviewed CT-based features of MP. Electronic medical records were reviewed for newly diagnosed malignancies with the following specific details: type (lymphoproliferative disease or solid malignancy), location (possible mesenteric drainage or distant), stage, time to diagnosis. An expert panel of three radiologists and one hemato-oncologist, who were blinded to the initial CT-based MP features, assessed the probability of association between MP and malignancy based on the malignancy characteristics. ResultsFrom 2006 to 2016, 444 patients with MP were included. There were 272 men and 172 women, with a median age of 64 years (age range: 25–89); the median overall follow-up was 36 months (IQR: 22, 60; range: 12–170). A total of 34 (8%) patients had a diagnosis of a new malignancy; 5 (1%) were considered possibly related to the MP, all being low-grade B-cell non-Hodgkin lymphomas. CT features associated with the presence of an underlying malignancy were the presence of an MP soft-tissue nodule with a short axis >10 mm (P < 0.0001) or lymphadenopathy in another abdominopelvic region (P < 0.0001). Associating these two features resulted in high diagnostic performance (sensitivity 100%; [95% CI: 57–100]; specificity 99% [95% CI: 98–100]). All related malignancies were identified. ConclusionFurther workup to rule out an underlying malignancy is only necessary in the presence of an MP soft-tissue nodule >10 mm or associated abdominopelvic lymphadenopathy.

Effect of more versus less frequent abdominopelvic computed tomography follow-up testing on overall survival in patients with stage II or III colon cancer.

3604 Background: Patients with colon cancer undergo an abdominopelvic computed tomography (AP-CT) scan surveillance every 6-12 months for five years after surgery. However, evidence of survival benefit from more intensive AP-CT patients in stage II and III colon cancer is still elusive. Methods: A total of 2,137 patients with stage II-III colon cancer who received curative aim surgery were analyzed in the Yonsei Cancer Registry Database between Jan 1, 2005, to Dec 31, 2015. The surveillance start date was defined as 90 days after curative resection or one day after adjuvant chemotherapy. All patients had at least one AP-CT for two years after the surveillance period. The average interval of AP-CT per patient was calculated as the postoperative surveillance duration divided by the number of AP-CT examinations. Patients who underwent AP-CT with an average interval of 6 months and 12 months were assigned to the high-frequent and low-frequent surveillance groups. Association of AP-CT frequency and demographic factors with overall survival (OS) were evaluated. Univariate and multivariate analyses were conducted. Results: Among 2,137 patients who underwent curative aim surgery, the median intervals of AP-CT scan were 6.1 months in high-frequent surveillance and 10.8 months in the less-frequent surveillance group, respectively. The 5-year overall survival (OS) was not significantly different in both groups; however, OS was significantly longer in the high-frequent surveillance group of patients who harvested lymph nodes less than 12 in curative resection ( P = 0.015) or measured postoperative serum carcinoembryonic antigen (CEA) level higher than 5 ng/ml ( P = 0.023). Of note, high-frequent surveillance group detected liver metastasis earlier (6.7 months) than the low-frequent group, leading to more curative aim metastasectomy (28.0% vs 4.3%, P = 0.020), and significantly longer 5-year OS (62.2% vs 34.8%, P = 0.017). Multivariate analysis showed that harvesting lymph nodes less than 12 (HR = 4.37, P = 0.004) and postoperative CEA level higher than 5 ng/ml (HR = 7.39, P &lt; 0.001) were prognostic factors for overall survival. Conclusions: The average interval of AP-CT in patients with stage II-III colon cancer is not associated with improved OS. However, a high-frequent AP-CT enabled early detection of liver metastases, leading to the improved OS in high-risk patients, including the number of harvested lymph nodes less than 12 or postoperative CEA level is higher than 5 ng/ml. The risk-stratified approach is warranted to guide postoperative colon cancer surveillance.

Radiation dose and cancer risks from radiation exposure during abdominopelvic computed tomography (CT) scans: comparison of diagnostic and radiotherapy treatment planning CT scans.

In the present study, radiation doses and cancer risks resulting from abdominopelvic radiotherapy planning computed tomography (RP-CT) and abdominopelvic diagnostic CT (DG-CT) examinations are compared. Two groups of patients who underwent abdominopelvic CT scans with RP-CT (n = 50) and DG-CT (n = 50) voluntarily participated in this study. The two groups of patients had approximately similar demographic features including mass, height, body mass index, sex, and age. Radiation dose parameters included CTDIvol, dose-length product, scan length, effective tube current, and pitch factor, all taken from the CT scanner console. The ImPACT software was used to calculate the patient-specific radiation doses. The risks of cancer incidence and mortality were estimated based on the BEIR VII report of the US National Research Council. In the RP-CT group, the mean ± standard deviation of cancer incidence risk for all cancers, leukemia, and all solid cancers was 621.58 ± 214.76, 101.59 ± 27.15, and 516.60 ± 189.01 cancers per 100,000 individuals, respectively, for male patients. For female patients, the corresponding risks were 742.71 ± 292.35, 74.26 ± 20.26, and 667.03 ± 275.67 cancers per 100,000 individuals, respectively. In contrast, for DG-CT cancer incidence risks were 470.22 ± 170.07, 78.23 ± 18.22, and 390.25 ± 152.82 cancers per 100,000 individuals for male patients, while they were 638.65 ± 232.93, 62.14 ± 13.74, and 575.73 ± 221.21 cancers per 100,000 individuals for female patients. Cancer incidence and mortality risks were greater for RP-CT than for DG-CT scans. It is concluded that the various protocols of abdominopelvic CT scans, especially the RP-CT scans, should be optimized with respect to the radiation doses associated with these scans.

The CT scout view: complementary value added to abdominal CT interpretation.

Computed tomography (CT) scout images, also known as CT localizer radiographs, topograms, or scanograms, are an important, albeit often overlooked part of the CT examination. Scout images may contain important findings outside of the scanned field of view on CT examinations of the abdomen and pelvis, such as unsuspected lung cancer at the lung bases. Alternatively, scout images can provide complementary information to findings within the scanned field of view, such as characterization of retained surgical foreign bodies. Assessment of scout images adds value and provides a complementary "opportunistic" review for interpretation of abdominopelvic CT examinations. Scout image review is a useful modern application of conventional abdominal radiograph interpretation that can help establish a diagnosis or narrow a differential diagnosis. This review discusses the primary purpose and intent of the CT scout images, addresses standard of care and bias related to scout image review, and presents a general systematic approach to assessing scout images with multiple illustrative examples, including potential pitfalls in interpreting scout images.

Risk of Hematologic Malignant Neoplasms From Abdominopelvic Computed Tomographic Radiation in Patients Who Underwent Appendectomy

Whether computed tomography (CT) radiation is truly carcinogenic remains controversial. Large epidemiological studies that purportedly showed an association between CT radiation and carcinogenesis were limited by confounding by indication and reverse causation, because the reasons for CT examination were unknown. To measure the risk of hematologic malignant neoplasms associated with perioperative abdominopelvic CT radiation among patients who underwent appendectomy for acute appendicitis. This nationwide population-based cohort study used the National Health Insurance Service claims database in South Korea to assess 825 820 patients who underwent appendectomy for appendicitis from January 1, 2005, to December 31, 2015, and had no underlying risk factors for cancer. Patients were divided into CT-exposed (n = 306 727) or CT-unexposed (n = 519 093) groups. The study was terminated on December 31, 2017, and data were analyzed from October 30, 2018, to September 27, 2020. Perioperative abdominopelvic CT examination from 7 days before to 7 days after appendectomy. The primary outcome was the incidence rate ratio (IRR) of hematologic malignant neoplasms for both groups. The secondary outcomes were IRR of abdominopelvic organ cancers and IRR of all cancers. The lag period was 2 years for the primary outcome and 5 years for secondary outcomes. The IRRs were calculated using Poisson regression models with adjustment for age and sex. Among the study population of 825 820 patients (52.9% male; median age, 28 [interquartile range, 15-41] years), hematologic malignant neoplasms developed in 323 patients in the CT-exposed group during 1 486 518 person-years and 500 patients in the CT-unexposed group during 3 422 059 person-years. For all hematologic malignant neoplasms, the IRR for the CT-exposed vs CT-unexposed group was 1.26 (95% CI, 1.09-1.45; P = .002). In terms of individual categories of hematologic malignant neoplasms, the CT-exposed group had an elevated risk only for leukemia (IRR, 1.40 [98.75% CI, 1.04-1.87, adjusted by Bonferroni correction]; P = .005). There was no between-group difference in incidence rate of abdominopelvic organ cancers (IRR, 1.07 [95% CI, 1.00-1.15]; P = .06) and that of all cancers (IRR, 1.04 [95% CI, 0.99-1.09]; P = .14). This study controlled for reverse causation bias by defining the reasons for CT scan, and findings suggest that abdominopelvic CT radiation is associated with a higher incidence of hematologic malignant neoplasms. Efforts should be continued for judicious use of CT examinations.

A database of 40 patient-based computational models for benchmarking organ dose estimates in CT.

Patient radiation burden in computed tomography (CT) can best be characterized through risk estimates derived from organ doses. Organ doses can be estimated by Monte Carlo simulations of the CT procedures on computational phantoms assumed to emulate the patients. However, the results are subject to uncertainties related to how accurately the patient and CT procedure are modeled. Different methods can lead to different results. This paper, based on decades of organ dosimetry research, offers a database of CT scans, scan specifics, and organ doses computed using a validated Monte Carlo simulation of each patient and acquisition. It is aimed that the database can serve as means to benchmark different organ dose estimation methods against a benchmark dataset. Organ doses were estimated for 40 adult patients (22 male, 18 female) who underwent chest and abdominopelvic CT examinations. Patient-based computational models were created for each patient including 26 organs for female and 25 organs for male cases. A Monte Carlo code, previously validated experimentally, was applied to calculate organ doses under constant and two modulated tube current conditions. The generated database reports organ dose values for chest and abdominopelvic examinations per patient and imaging condition. Patient information and images and scan specifications (energy spectrum, bowtie filter specification, and tube current profiles) are provided. The database is available at publicly accessible digital repositories. Consistency in patient risk estimation, and associated justification and optimization requires accuracy and consistency in organ dose estimation. The database provided in this paper is a helpful tool to benchmark different organ dose estimation methodologies to facilitate comparisons, assess uncertainties, and improve risk assessment of CT scans based on organ dose.

Is visceral obesity associated with colorectal cancer? The first volumetric study using all CT slices.

We aimed to examine the possible relationship between abdominal adiposity parameters and the presence of colorectal cancer (CRC) and between these adiposity parameters and various histopathologic findings of the tumor. A total of 60 control subjects and 111 CRC patients, 63 with early-stage and 48 with advanced-stage disease, were enrolled. Medical data and abdominopelvic computed tomography (CT) examinations of each study group were retrospectively reviewed. Abdominal adiposity parameters, including visceral adipose tissue (VAT) volume, subcutaneous adipose tissue (SAT) volume, and total adipose tissue (TAT) volume, were calculated on all slices of the CT examinations with specialized software, and results for each study group were compared. Adiposity parameters were also compared with tumor histopathologic findings. We found lower VAT and higher SAT volumes in advanced-stage CRC patients, compared with the early-stage group. However, this relationship was not statistically significant (P = 0.721 for VAT and P = 0.432 for SAT volumes). We detected significantly lower VAT and SAT volumes in the early-stage CRC group compared with the control group (P = 0.014 for both). There was no significant relationship between TAT volumes and the study groups (P = 0.06). No statistically significant relationship was detected between adipose tissue parameters and histopathologic features of the CRC group (P > 0.05). We found statistically significant lower VAT and SAT volumes in patients with early-stage CRC compared with the control group. Volumetric adipose tissue measurements may be more accurate than area measurements and can easily be performed on abdominopelvic CT examination, which is the routine imaging modality for CRC patients.

Value and necessity of pelvic CT in gastric cancer staging: an observational study

Background: The value and necessity of pelvic computed tomography (CT) examination in gastric cancer (GC) staging is unknown and the recommendations are unclear in guidelines. The objective of this study was to evaluate the value and necessity of pelvic CT in routine GC staging.Methods: We reviewed the medical records of GC patients proved by endoscopic biopsy who received abdominopelvic CT examination before treatments at our institution from January 2013 through July 2017. The pathology findings seen in the pelvis were classified into two categories as metastatic disease or not. These findings were further categorized as isolated pelvis metastasis or not, and isolated pelvis metastasis was defined as the presence of pelvis metastasis without any other sites of metastasis on CT scan.Results: A total of 227 GC patients received abdominopelvic CT examinations at our institution. Of the patients, 22.0% (n = 50) had findings in the pelvis, and the most common was ascites (8.8%, n = 20). The metastatic diseases in pelvis were found in 2.2% (n = 5) of all patients, including peritoneal thickening with nodules, left adnexal solid masses, bladder wall mass, bone lesions, and lymphatic spread. The isolated pelvis metastasis was found in 1.3% (n = 3) of patients.Conclusions: Our results indicated that CT of the pelvis has a negligible yield in GC staging. In consideration of health care cost, radiation dose and radiologist fatigue, the pelvic CT performed as a routine staging tool for GC is unnecessary and not a wise choice in our setting.

Experience With Iterative Reconstruction Techniques for Abdominopelvic Computed Tomography in Morbidly and Super Obese Patients.

The aim of this study was to investigate the diagnostic performance of abdominopelvic computed tomography (CT) images reconstructed using filtered back projection (FBP) and iterative reconstruction (IR) algorithms in morbidly and super obese patients. One hundred eighty-seven abdominopelvic CT examinations in portal venous phase were performed between February 2015 and February 2016 in 182 patients (mean age = 52 years, mean body mass index = 45.5). One hundred fourteen of 187 examinations were reconstructed using IR and 73 examinations were processed using FBP. Patients were further stratified based on body mass index. Sixty CT scans were reviewed by a single reader for image quality, image noise, and artifacts. Objective noise and attenuation were also determined. Size-specific dose estimate and CT dose index volume were compared and statistically analyzed. A diagnostic interpretation was rendered for all 187 examinations. A single-reader review of 60 cases showed greater diagnostic acceptability for IR when compared with FBP (image quality = 4.2 and 3.8 [P = 0.035], noise = 1.5 and 1.6 [P = 0.692], artifact = 1.4 and 1.5 [P = 0.759], respectively). For all examinations, the IR group had lower objective image noise (IR = 9.3 and FBP = 14.3; P < 0.001) and higher contrast-to-noise ratio (IR = 17.2 and FBP = 11.7; P < 0.001) without increase in radiation dose (size-specific dose estimate [IR = 15.1, FBP = 16.5 mGy; P = 0.045] and CT dose index volume [IR = 17.6, FBP = 18 mGy; P = 0.62]). In morbidly and super obese patients, diagnostic quality images could be reliably generated with minimal artifacts and noise using newer generation scanners integrated with IR without increasing radiation dose.

DEVELOPMENT OF AGE-SPECIFIC JAPANESE PHYSICAL PHANTOMS FOR DOSE EVALUATION IN INFANT CT EXAMINATIONS.

Secondary to the previous development of age-specific Japanese head phantoms, the authors designed Japanese torso phantoms for dose assessment in infant computed tomography (CT) examinations and completed a Japanese 3-y-old head-torso phantom. For design of age-specific torso phantoms (0, 0.5, 1 and 3 y old), anatomical structures were measured from CT images of Japanese infant patients. From the CT morphometry, it was found that rib cages of Japanese infants were smaller than those in Europeans and Americans. Radiophotoluminescence glass dosemeters were used for dose measurement of a 3-y-old head-torso phantom. To examine the validity of the developed phantom, organ and effective doses by the in-phantom dosimetry system were compared with simulation values in a web-based CT dose calculation system (WAZA-ARI). The differences in doses between the two systems were <20 % at the doses of organs within scan regions and effective doses in head, chest and abdominopelvic CT examinations.

Effect of an Institutional Triaging Algorithm on the Use of Multidetector CT for Patients with Blunt Abdominopelvic Trauma over an 8-year Period.

Purpose To evaluate the effect of an institutional clinical triaging algorithm on the rate of multidetector computed tomography (CT) utilization in blunt abdominopelvic trauma (BAPT) over an 8-year period at an urban level 1 trauma center. Materials and Methods Adult patients (n = 13 096; mean age, 42 years; age range, 15-95 years) admitted with BAPT from January 1, 2006, to December 31, 2013, were included. Patients with BAPT were divided into two groups: those admitted before (referred to as the prealgorithm group, from January 1, 2006, to June 30, 2010) and after (referred to as the postalgorithm group, from July 1, 2010, to December 31, 2013) the implementation of an institutional clinical triaging algorithm. The following parameters were recorded from abdominopelvic CT study reports for the pre- and postalgorithm groups: number of abdominopelvic CT examinations at admission, number of abdominopelvic CT examinations with positive BAPT-related findings, injury severity score, length of hospital stay, and number of mortalities. The unpaired t test and χ2 analysis were used to determine significant differences. Results The percentage of patients admitted for BAPT who underwent an abdominopelvic CT study was 76.7% (5900 of 7688) in the prealgorithm group and 44.6% (2413 of 5408) in the postalgorithm group, a 32.1% decrease in use of CT (P < .001). The mean injury severity score increased from 10.1 ± 9.1 (standard deviation) to 13.3 ± 11.9 after implementation of the algorithm in patients admitted for BAPT who underwent abdominopelvic CT examination (P < .001). The percentage of abdominopelvic CT examinations with BAPT-related findings increased from 17.1% (1007 of 5900) to 19.8% (479 of 2413) (P = .003). There was a significant difference in average length of stay, from 4.8 days ± 7.0 to 4.2 days ± 6.2 (P < .001). Mortality decreased from 3.1% (242 of 7688) to 2.7% (148 of 5408) after implementation of the algorithm (P = .19). Conclusion The implementation of a clinical triaging algorithm resulted in decreased use of multidetector CT in patients who presented with BAPT to the emergency department. © RSNA, 2016.

Assessing the Appropriateness of Outpatient Abdominopelvic CT and MRI Examinations Using the American College of Radiology Appropriateness Criteria

To retrospectively assess the appropriateness of outpatient abdominal and pelvic computed tomography (CT) and magnetic resonance imaging (MRI) examinations using the American College of Radiology Appropriateness Criteria (AC). A total of 570 adult outpatient abdominopelvic CT (304) and MRI (266) studies performed in a 1-month period with available documentation of the clinical encounter generating the imaging order were included. On the basis of review of the imaging report and patient record, examinations were classified in terms of match to a specific AC variant, appropriateness score, and the presence of a significant result. Data were analyzed using Fisher's exact test. Forty-five percent of examinations matched an AC variant: 52% of CT and 38% of MRI (P<.001). Ninety-two percent of examinations matching the AC were appropriate: 96% of CT and 86% of MRI (P=.009). Appropriate examinations were more likely to provide a significant result than not appropriate studies (48% vs. 24%, P=.041). Although a significant result was related to the primary study indication more frequently in appropriate than not appropriate examinations, this difference was not significant (93% vs. 80%, respectively, P=.204). The most common indications not matching an AC were colon cancer follow-up (n=14) and melanoma follow-up (n=14) among CT, and hepatocellular carcinoma screening (n=31) and elevated prostate-specific antigen (PSA) without prior biopsy (n=14) among MRI. Most examinations matching the AC were appropriate, and appropriate examinations were more likely to have a significant result. However, most examinations, including 62% of MRI, had no relevant clinical condition, highlighting a critical area for future AC expansion and modification.

Imaging for appendicitis: should radiation-induced cancer risks affect modality selection?

To compare life expectancy (LE) losses attributable to three imaging strategies for appendicitis in adults-computed tomography (CT), ultrasonography (US) followed by CT for negative or indeterminate US results, and magnetic resonance (MR) imaging-by using a decision-analytic model. In this model, for each imaging strategy, LE losses for 20-, 40-, and 65-year-old men and women were computed as a function of five key variables: baseline cohort LE, test performance, surgical mortality, risk of death from delayed diagnosis (missed appendicitis), and LE loss attributable to radiation-induced cancer death. Appendicitis prevalence, test performance, mortality rates from surgery and missed appendicitis, and radiation doses from CT were elicited from the published literature and institutional data. LE loss attributable to radiation exposure was projected by using a separate organ-specific model that accounted for anatomic coverage during a typical abdominopelvic CT examination. One- and two-way sensitivity analyses were performed to evaluate effects of model input variability on results. Outcomes across imaging strategies differed minimally-for example, for 20-year-old men, corresponding LE losses were 5.8 days (MR imaging), 6.8 days (combined US and CT), and 8.2 days (CT). This order was sensitive to differences in test performance but was insensitive to variation in radiation-induced cancer deaths. For example, in the same cohort, MR imaging sensitivity had to be 91% at minimum (if specificity were 100%), and MR imaging specificity had to be 62% at minimum (if sensitivity were 100%) to incur the least LE loss. Conversely, LE loss attributable to radiation exposure would need to decrease by 74-fold for combined US and CT, instead of MR imaging, to incur the least LE loss. The specific imaging strategy used to diagnose appendicitis minimally affects outcomes. Paradigm shifts to MR imaging owing to concerns over radiation should be considered only if MR imaging test performance is very high.

Prospective Randomized Trial of Iohexol 350 Versus Meglumine Sodium Diatrizoate as an Oral Contrast Agent for Abdominopelvic Computed Tomography

To compare the efficacy and patient tolerance of iohexol and meglumine sodium diatrizoate as oral contrast agents for computed tomography (CT). One hundred patients were randomly assigned to drink 1000 mL of either meglumine sodium diatrizoate or iohexol 350 before their abdominopelvic CT examination. The images were evaluated independently and in a blinded fashion by 2 radiologists who scored the extent and density of bowel opacification. Attenuation value measurements were obtained in representative areas of each gastrointestinal tract segment (stomach, duodenum, jejunum, ileum, and colon) by a research technologist. Patients' tolerance of the oral contrast agent was assessed through a questionnaire administered immediately after the CT and with a follow-up phone call 2 to 3 days later. For most of the bowel, there was no statistically significant difference in the extent or degree of opacification between the 2 contrast agents. Opacification of the ileum was better with iohexol. There was no statistically significant difference between the 2 agents in adverse effects. Patients had a small but statistically significant preference for the taste of iohexol. Iohexol 350 is a satisfactory oral contrast agent for abdominopelvic CT. It opacifies the gastrointestinal tract as well as meglumine sodium diatrizoate does, and patients prefer the taste of iohexol to that of diatrizoate.

Benefit of follow-up CT in emergency department patients with persistent non-traumatic abdominal pain

To determine the benefit of a short-term follow-up abdominopelvic computed tomography (APCT) examination among emergency department (ED) patients with persistent abdominal pain and an initially negative CT. During a 5-year period from January 2004 to December 2008, our institution's radiology department performed approximately 56,000 APCTs examinations in the ED. Sixty-eight percent of the APCT examinations used intravenous contrast. Nine hundred fifty-seven patients received two APCTs within 1 week for non-traumatic abdominal pain in the ED. Sixty-four patients with initially negative APCTs presented to the ED within 1 week with persistent abdominal pain and received follow-up APCT imaging. The mean follow-up period was 2.6 days. The mean interval period in which the second APCT yielded a positive result was 2.0 days. Seventy-five percent of follow-up examinations were performed with intravenous contrast. Twenty-three percent of patients had positive findings on the follow-up examination. Seventy-three percent of the follow-up positive findings were referable to bowel pathology. The cause of abdominal pain remained elusive at 1 week in 23% of patients. Short-term follow-up APCT examinations in patients with persistent, unexplained abdominal pain may be of benefit if the second APCT is performed with intravenous contrast in patients suspected of having bowel pathology.