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1.  Exposure to Low-Dose Ionizing Radiation from Medical Imaging Procedures in the United States 
The New England journal of medicine  2009;361(9):849-857.
Growing use of imaging procedures in the United States has raised concerns about exposure to low-dose ionizing radiation in the general population.
We identified 952,420 non-elderly adults in 5 healthcare markets across the United States between July 1, 2005 and December 31, 2007. Utilization data were used to determine cumulative effective doses of radiation from imaging procedures in millisieverts (mSv) and to calculate population-based rates of “moderate” (>3 to 20 mSv per year), “high” (>20 to 50 mSv per year) and “very-high” (>50 mSv per year) doses.
During the study period, 655,613 (68.8%) individuals underwent at least 1 imaging procedure associated with radiation exposure. The mean effective dose from imaging procedures was 2.4 mSv per person per year (std dev, 6.0 mSv); however, a wide distribution was noted with a median effective dose of 0.1 mSv per person per year (interquartile range, 0.0 to 1.7). Overall, the annual rate for moderate effective doses in the study population was 193.8 per 1000 enrollees, while high and very-high doses occurred at annual rates of 18.6 per 1000 enrollees and 1.9 per 1000 enrollees, respectively. In general, effective doses of radiation from imaging procedures increased with advancing age and were higher in women. Computed tomography and nuclear medicine scans accounted for 75.4% of the total effective dose and 81.8% occurred in non-hospitalized settings.
Imaging procedures are an important source of ionizing radiation in the United States and can lead to high radiation doses in patients.
PMCID: PMC3707303  PMID: 19710483
2.  Radiation Exposure from Abdominal Imaging Studies in Patients with Intestinal Behçet Disease 
Gut and Liver  2013;8(4):380-387.
Recently, several studies have revealed that diagnostic imaging can result in exposure to harmful levels of ionizing radiation in inflammatory bowel disease patients. However, the extent of radiation exposure in intestinal Behcet disease (BD) patients has not been documented. The aim of this study was to estimate the radiation exposure from abdominal imaging studies in intestinal BD patients.
Patients with a diagnosis of intestinal BD established between January 1990 and March 2012 were investigated at a single tertiary academic medical center. The cumulative effective dose (CED) was calculated retrospectively from standard tables and by counting the number of abdominal imaging studies performed. High exposure was defined as CED >50 mSv.
In total, 270 patients were included in the study. The mean CED was 41.3 mSv, and 28.1% of patients were exposed to high levels of radiation. Computed tomography (CT) accounted for 81.7% of the total effective dose. In multivariate analyses, predictors of high radiation exposure were azathioprine/6-mercaptopurine use, surgery, and hospitalization.
Approximately a quarter of intestinal BD patients were exposed to harmful levels of diagnostic radiation, mainly from CT examination. Clinicians should reduce the number of unnecessary CT examinations and consider low-dose CT profiles or alternative modalities such as magnetic resonance enterography.
PMCID: PMC4113057  PMID: 25071902
Intestinal Behcet disease; Clinical course; Prognostic factors; Radiation
3.  Cumulative Exposure to Ionizing Radiation from Diagnostic and Therapeutic Cardiac Imaging Procedures: A Population-Based Analysis 
To describe radiation exposure from cardiac imaging procedures over time in a general population.
Cardiac imaging procedures frequently expose patients to ionizing radiation, but their contribution to effective doses of radiation in the general population is unknown.
We used administrative claims to identify cardiac imaging procedures performed from 2005-2007 in 952,420 non-elderly insured adults in 5 U.S. healthcare markets. We estimated 3-year cumulative effective doses of radiation in millisieverts (mSv) from these procedures We then calculated population-based annual rates of radiation exposure to effective doses ≤3 mSv/year (background level of radiation from natural sources), >3-20 mSv/year, or >20 mSv/year (upper annual limit for occupational exposure averaged over 5 years).
90,121 (9.5%) individuals underwent at least one cardiac imaging procedure using radiation. Among patients who underwent ≥1 cardiac imaging procedure, the mean cumulative effective dose over 3 years was 16.4 mSv (range 1.5-189.5 mSv). Myocardial perfusion imaging accounted for 74% of the cumulative effective dose. Overall, 47.8% of cardiac imaging procedures were performed in physician offices; this proportion was higher for myocardial perfusion imaging (74.8%) and cardiac CT studies (76.5%). The annual population-based rate of receiving an effective dose of >3-20 mSv/year was 89.0 per 1000; and 3.3 per 1000 for cumulative doses >20 mSv/year. Annual effective doses increased with age and were generally higher among men.
Cardiac imaging procedures lead to substantial radiation exposure and effective doses for many patients in the United States.
PMCID: PMC2952402  PMID: 20619569
radiation; imaging; epidemiology
4.  Does Iterative Reconstruction Lower CT Radiation Dose: Evaluation of 15,000 Examinations 
PLoS ONE  2013;8(11):e81141.
Evaluation of 15,000 computed tomography (CT) examinations to investigate if iterative reconstruction (IR) reduces sustainably radiation exposure.
Method and Materials
Information from 15,000 CT examinations was collected, including all aspects of the exams such as scan parameter, patient information, and reconstruction instructions. The examinations were acquired between January 2010 and December 2012, while after 15 months a first generation IR algorithm was installed. To collect the necessary information from PACS, RIS, MPPS and structured reports a Dose Monitoring System was developed. To harvest all possible information an optical character recognition system was integrated, for example to collect information from the screenshot CT-dose report. The tool transfers all data to a database for further processing such as the calculation of effective dose and organ doses. To evaluate if IR provides a sustainable dose reduction, the effective dose values were statistically analyzed with respect to protocol type, diagnostic indication, and patient population.
IR has the potential to reduce radiation dose significantly. Before clinical introduction of IR the average effective dose was 10.1±7.8mSv and with IR 8.9±7.1mSv (p*=0.01). Especially in CTA, with the possibility to use kV reduction protocols, such as in aortic CTAs (before IR: average14.2±7.8mSv; median11.4mSv /with IR:average9.9±7.4mSv; median7.4mSv), or pulmonary CTAs (before IR: average9.7±6.2mSV; median7.7mSv /with IR: average6.4±4.7mSv; median4.8mSv) the dose reduction effect is significant(p*=0.01). On the contrary for unenhanced low-dose scans of the cranial (for example sinuses) the reduction is not significant (before IR:average6.6±5.8mSv; median3.9mSv/with IR:average6.0±3.1mSV; median3.2mSv).
The dose aspect remains a priority in CT research. Iterative reconstruction algorithms reduce sustainably and significantly radiation dose in the clinical routine. Our results illustrate that not only in studies with a limited number of patients but also in the clinical routine, IRs provide long-term dose saving.
PMCID: PMC3841128  PMID: 24303035
5.  Multiple Testing, Cumulative Radiation Dose, and Clinical Indications in Patients Undergoing Myocardial Perfusion Imaging 
Myocardial perfusion imaging (MPI) is the single medical test with the highest radiation burden to the US population. While many patients undergoing MPI receive repeat MPI testing, or additional procedures involving ionizing radiation, no data are available characterizing their total longitudinal radiation burden and relating radiation burden with reasons for testing.
To characterize procedure counts, cumulative estimated effective doses of radiation, and clinical indications, for patients undergoing MPI.
Design, Setting, Patients
Retrospective cohort study evaluating, for 1097 consecutive patients undergoing index MPI during the first 100 days of 2006 at Columbia University Medical Center, all preceding medical imaging procedures involving ionizing radiation undergone beginning October 1988, and all subsequent procedures through June 2008, at that center.
Main Outcome Measures
Cumulative estimated effective dose of radiation, number of procedures involving radiation, and indications for testing.
Patients underwent a median (interquartile range, mean) of 15 (6–32, 23.9) procedures involving radiation exposure; 4 (2–8, 6.5) were high-dose (≥3 mSv, i.e. one year's background radiation), including 1 (1–2, 1.8) MPI studies per patient. 31% of patients received cumulative estimated effective dose from all medical sources >100mSv. Multiple MPIs were performed in 39% of patients, for whom cumulative estimated effective dose was 121 (81–189, 149) mSv. Men and whites had higher cumulative estimated effective doses, and there was a trend towards men being more likely to undergo multiple MPIs than women (40.8% vs. 36.6%, Odds ratio 1.29, 95% confidence interval 0.98–1.69). Over 80% of initial and 90% of repeat MPI exams were performed in patients with known cardiac disease or symptoms consistent with it.
In this institution, multiple testing with MPI was very common, and in many patients associated with very high cumulative estimated doses of radiation.
PMCID: PMC3667407  PMID: 21078807
6.  Analysis of Germline GLI1 Variation Implicates Hedgehog Signalling in the Regulation of Intestinal Inflammatory Pathways 
PLoS Medicine  2008;5(12):e239.
Ulcerative colitis (UC) and Crohn's disease (CD) are polygenic chronic inflammatory bowel diseases (IBD) of high prevalence that are associated with considerable morbidity. The hedgehog (HH) signalling pathway, which includes the transcription factor glioma-associated oncogene homolog 1 (GLI1), plays vital roles in gastrointestinal tract development, homeostasis, and malignancy. We identified a germline variation in GLI1 (within the IBD2 linkage region, 12q13) in patients with IBD. Since this IBD-associated variant encodes a GLI1 protein with reduced function and our expression studies demonstrated down-regulation of the HH response in IBD, we tested whether mice with reduced Gli1 activity demonstrate increased susceptibility to chemically induced colitis.
Methods and Findings
Using a gene-wide haplotype-tagging approach, germline GLI1 variation was examined in three independent populations of IBD patients and healthy controls from Northern Europe (Scotland, England, and Sweden) totalling over 5,000 individuals. On log-likelihood analysis, GLI1 was associated with IBD, predominantly UC, in Scotland and England (p < 0.0001). A nonsynonymous SNP (rs2228226C→G), in exon 12 of GLI1 (Q1100E) was strongly implicated, with pooled odds ratio of 1.194 (confidence interval = 1.09–1.31, p = 0.0002). GLI1 variants were tested in vitro for transcriptional activity in luciferase assays. Q1100E falls within a conserved motif near the C terminus of GLI1; the variant GLI protein exhibited reduced transactivation function in vitro. In complementary expression studies, we noted the colonic HH response, including GLI1, patched (PTCH), and hedgehog-interacting protein (HHIP), to be down-regulated in patients with UC. Finally, Gli1+/lacZ mice were tested for susceptibility to dextran sodium sulphate (DSS)-induced colitis. Clinical response, histology, and expression of inflammatory cytokines and chemokines were recorded. Gli1+/lacZ mice rapidly developed severe intestinal inflammation, with considerable morbidity and mortality compared with wild type. Local myeloid cells were shown to be direct targets of HH signals and cytokine expression studies revealed robust up-regulation of IL-12, IL-17, and IL-23 in this model.
HH signalling through GLI1 is required for appropriate modulation of the intestinal response to acute inflammatory challenge. Reduced GLI1 function predisposes to a heightened myeloid response to inflammatory stimuli, potentially leading to IBD.
Charlie Lees and colleagues identify a reduced-function variant of the hedgehog signaling pathway protein GLI1 that associates with inflammatory bowel disease, and investigate its role in a mouse model of colitis.
Editors' Summary
Inflammatory bowel diseases (IBDs) are common disorders in which parts of the digestive tract become repeatedly or continuously inflamed. The immune system normally protects the body from entities it identifies as foreign, but in IBD it mistakenly recognizes gut tissue, and immune system cells accumulate in the lining of the bowel, which causes inflammation. There are two main types of IBD—Crohn's disease (CD), which mainly affects the small bowel, and ulcerative colitis (UC), which affects only the large bowel (colon). Both types tend to run in families and usually develop between the ages of 15 and 35 years. Symptoms—including diarrhea, abdominal cramps, and unexplained weight loss—can be mild or severe and the disease can develop slowly or suddenly. There is no cure for IBD except surgical removal of the affected part of the digestive tract. However, drugs that modulate the immune system (for example, corticosteroids) or that specifically inhibit “proinflammatory cytokines” (proteins made by the immune system that stimulate inflammation) are often helpful in reducing symptoms.
Why Was This Study Done?
Why the immune system becomes unbalanced in people with IBD is not clear but it is known that IBD is “polygenic,” that is, a disease caused by the combined actions of two or more inherited gene variants. Although UC and CD are clinically different diseases, they share several “susceptibility loci” (regions of the genome that harbor disease-associated gene variants), including the IBD2 locus. The identification of the actual gene within the IBD2 locus that is altered in people who are susceptible to IBD might provide new insights into what causes the immune imbalance in IBD and into how to treat the disease. In this study, the researchers test the hypothesis that a variant of a gene called GLI1, which lies in the IBD2 locus, is associated with IBD susceptibility. GLI1 encodes a transcription factor (a protein that regulates the production of proteins) that is a central component in the signaling pathway named for a protein called “hedgehog.” This pathway is involved in the development of many organs, including the digestive tract.
What Did the Researchers Do and Find?
The researchers used a technique called gene-wide haplotype tagging to look for inherited GLl1 variants in patients with IBD and in healthy people living in Scotland, England, and Sweden. A specific variant of the GLI1 gene, resulting in alteration of a single amino acid component of the GLI1 protein, was associated with IBD (particularly with UC) in both Scotland and England; the same variant was weakly associated with IBD in the Swedish population. The variant GLI1 protein was only half as active as the normal protein in a laboratory assay, and, consistent with this result, the expression of several components of the hedgehog signaling pathway was lower in colon samples taken from patients with UC than in samples taken from healthy individuals. Finally, Gli1+/lacZ mice (which express half the normal amount of Gli1 protein) developed severe intestinal inflammation more rapidly than wild-type mice when they were treated with dextran sodium sulfate (DSS), a chemical that induces acute (sudden) colitis. Cellular analysis revealed that myeloid cells (cells that sense and modify the inflammatory response) are direct targets of the hedgehog signaling pathway. Furthermore, the expression of several pro-inflammatory cytokines (in particular, one called IL-23) increased more markedly in the Gli1+/lacZ mice than in the wild-type mice after DSS treatment.
What Do These Findings Mean?
These findings suggest that the normal response of the mammalian gut to challenge with inflammatory substances involves hedgehog signaling through GLI1 and that reduced GLI1 function might be one trigger for IBD. More specifically, the human genetic studies identify a GLI1 variant that is associated with IBD (at least in certain north European populations), the laboratory experiments indicate that this GLI1 variant encodes a protein with reduced activity, and the animal studies show that a similar reduction in Gli1 activity is sufficient to heighten intestinal inflammatory responses. Although this last result needs to be confirmed in animal models of chronic colitis that more closely resemble human IBD, these findings suggest that drugs that modulate hedgehog signaling might be useful in the treatment of IBD.
Additional Information.
Please access these Web sites via the online version of this summary at
The MedlinePlus Encyclopedia has pages on Crohn's disease and on ulcerative colitis (in English and Spanish)
MedlinePlus provides links to other information Crohn's disease and ulcerative colitis (in English and Spanish)
The US National Institute of Diabetes and Digestive and Kidney Diseases provides information on Crohn's disease and ulcerative colitis
The UK National Health Service Direct Encyclopedia also provides information on Crohn's disease and on ulcerative colitis
Wikipedia has a page on the hedgehog signaling pathway (note: Wikipedia is a free online encyclopedia that anyone can edit; available in several languages)
PMCID: PMC2596854  PMID: 19071955
7.  An Antibiotic-Responsive Mouse Model of Fulminant Ulcerative Colitis  
PLoS Medicine  2008;5(3):e41.
The constellation of human inflammatory bowel disease (IBD) includes ulcerative colitis and Crohn's disease, which both display a wide spectrum in the severity of pathology. One theory is that multiple genetic hits to the host immune system may contribute to the susceptibility and severity of IBD. However, experimental proof of this concept is still lacking. Several genetic mouse models that each recapitulate some aspects of human IBD have utilized a single gene defect to induce colitis. However, none have produced pathology clearly distinguishable as either ulcerative colitis or Crohn's disease, in part because none of them reproduce the most severe forms of disease that are observed in human patients. This lack of severe IBD models has posed a challenge for research into pathogenic mechanisms and development of new treatments. We hypothesized that multiple genetic hits to the regulatory machinery that normally inhibits immune activation in the intestine would generate more severe, reproducible pathology that would mimic either ulcerative colitis or Crohn's disease.
Methods and Findings
We generated a novel mouse line (dnKO) that possessed defects in both TGFβRII and IL-10R2 signaling. These mice rapidly and reproducibly developed a disease resembling fulminant human ulcerative colitis that was quite distinct from the much longer and more variable course of pathology observed previously in mice possessing only single defects. Pathogenesis was driven by uncontrolled production of proinflammatory cytokines resulting in large part from T cell activation. The disease process could be significantly ameliorated by administration of antibodies against IFNγ and TNFα and was completely inhibited by a combination of broad-spectrum antibiotics.
Here, we develop to our knowledge the first mouse model of fulminant ulcerative colitis by combining multiple genetic hits in immune regulation and demonstrate that the resulting disease is sensitive to both anticytokine therapy and broad-spectrum antibiotics. These findings indicated the IL-10 and TGFβ pathways synergize to inhibit microbially induced production of proinflammatory cytokines, including IFNγ and TNFα, which are known to play a role in the pathogenesis of human ulcerative colitis. Our findings also provide evidence that broad-spectrum antibiotics may have an application in the treatment of patients with ulcerative colitis. This model system will be useful in the future to explore the microbial factors that induce immune activation and characterize how these interactions produce disease.
Paul Allen and colleagues describe the development of a mouse model of fulminant ulcerative colitis with multiple genetic hits in immune regulation which can be moderated by anti-cytokine therapy and broad-spectrum antibiotics.
Editors' Summary
Inflammatory bowel disease (IBD), a group of disorders characterized by inflammation (swelling) of the digestive tract (the tube that runs from the mouth to the anus), affects about 1.4 million people in the US. There are two main types of IBD. In Crohn's disease, which can affect any area of the digestive tract but most commonly involves the lower part of the small intestine (small bowel), all the layers of the intestine become inflamed. In ulcerative colitis, which primarily affects the colon (large bowel) and the rectum (the part of the bowel closest to the anus), only the lining of the bowel becomes inflamed, the cells in this lining die, and sores or ulcers form. Both types of IBD most commonly develop between the ages of 15 and 35 years, often run in families, and carry an increased risk of cancer. Symptoms—usually diarrhea and abdominal cramps—can be mild or severe and the disorder can develop slowly or suddenly. There is no medical cure for IBD, but drugs that modulate the immune system (for example, corticosteroids) can help some people. Some people benefit from treatment with drugs that specifically inhibit “proinflammatory cytokines,” proteins made by the immune system that stimulate inflammation (for example, TNFα and INFγ). When medical therapy fails, surgery to remove the affected part of the bowel may be necessary.
Why Was This Study Done?
Exactly what causes IBD is not clear, but people with IBD seem to have an overactive immune system. The immune system normally protects the body from harmful substances but in IBD it mistakenly recognizes the food substances and “good” bacteria that are normally present in the human gut as foreign and hence reacts against them. As a result, immune system cells accumulate in the lining of the bowel and cause inflammation. Several different pathways usually prevent inappropriate immune activation, so could IBD be caused by alterations in one or several of these immune regulatory pathways? In previous studies, mice with a defect in just one pathway have developed mild intestinal abnormalities but not the problems seen in the most severe forms of IBD. In this study, therefore, the researchers have generated and characterized a new mouse line with defects in two immune regulatory pathways to see whether this might be a better animal model of human IBD.
What Did the Researchers Do and Find?
To make their new mouse line, the researchers mated mice that had a defective TGFβ signaling pathway in their T lymphocytes with mice that had a defective IL-10 signaling pathway. Both these pathways are anti-inflammatory, and mice with defects in either pathway develop mild and variable inflammation of the colon (colitis) by age 3–4 months. By contrast, the doubly defective mice (dnKO mice) failed to thrive, lost weight, and died by 4–6 weeks of age. The colons of 4- to 5-week old dnKO mice were inflamed and ulcerated (some changes were visible in 3-week-old mice) and contained many immune system cells. Mice with a single defective signaling pathway had no gut abnormalities at this age. The dnKO mice, just like people with IBD, had higher than normal blood levels of IFNγ, TNFα, and other proinflammatory cytokines; these raised levels were the result of abnormal lymphocyte activation. Treatment of the dnKO mice with a combination of agents that neutralize IFNγ and TNFα (anti-cytokine therapy) greatly reduced the colitis seen in these mice; neutralization of IFNγ alone had some beneficial effects, but neutralization of TNFα alone had no effect. Finally, early treatment of the dnKO mice with broad-spectrum antibiotics completely inhibited colitis.
What Do These Findings Mean?
These findings suggest that dnKO mice are a good model for fulminant (severe and rapidly progressing) ulcerative colitis and support the idea that IBD involves multiple genetic defects in immune regulation. They also indicate that the IL-10 and the TGFβ signaling pathways normally cooperate to inhibit the inappropriate immune responses to intestinal bacteria seen in IBD. This new mouse model should help researchers unravel what goes wrong in IBD and should also help them develop new treatments for ulcerative colitis. More immediately, these findings suggest that combined anti-cytokine therapy may be a better treatment for ulcerative colitis than single therapy. In addition, they suggest that clinical studies should be started to test whether broad-spectrum antibiotics can ameliorate ulcerative colitis in people.
Additional Information.
Please access these Web sites via the online version of this summary at
The Medline Plus Encyclopedia has pages on Crohn's disease and on ulcerative colitis (in English and Spanish)
Information is available from the UK National Health Service Direct Health Encyclopedia about Crohn's disease and ulcerative colitis
The US National Institute of Diabetes and Digestive and Kidney Diseases provides information on Crohn's disease and ulcerative colitis
Information and support for patients with inflammatory bowel disease and their caregivers is provided by the Crohn's and Colitis Foundation of America and by the UK National Association for Colitis and Crohn's Disease
PMCID: PMC2270287  PMID: 18318596
8.  A pilot study of transrectal endoscopic ultrasound elastography in inflammatory bowel disease 
BMC Gastroenterology  2011;11:113.
Using standard diagnostic algorithms it is not always possible to establish the correct phenotype of inflammatory bowel disease which is essential for therapeutical decisions. Endoscopic ultrasound elastography is a new endoscopic procedure which can differentiate the stiffness of normal and pathological tissue by ultrasound. Therefore, we aimed to investigate the role of transrectal ultrasound elastography in distiction between Crohn's disease and ulcerative colitis.
A total 30 Crohn's disease, 25 ulcerative colitis, and 28 non-inflammatory bowel disease controls were included. Transrectal ultrasound elastography was performed in all patients and controls. In all ulcerative coltis patients and 80% of Crohn's disease patients endoscopy was performed to assess disease activity in the rectum.
Significant difference in rectal wall thickness and strain ratio was detected between patients with Crohn's disease and controls (p = 0.0001). CD patients with active disease had higher strain ratio than patients in remission (p = 0.02). In ulcerative colitis group a significant difference in rectal wall thickness was found between controls and patients with active disease (p = 0.03). A significant difference in rectal wall thickness (p = 0.02) and strain ratio (p = 0.0001) was detected between Crohn's disease and ulcerative colitis patient group. Crohn's disease patients with active disease had a significantly higher strain ratio compared to ulcerative colitis patients with active disease (p = 0.0001).
Transrectal ultrasound elastography seems to be a promising new diagnostic tool in the field of inflammatory bowel disease. Further study on a larger cohort of patients is needed to definitely assess the role of transrectal ultrasound elastography in inflammatory bowel disease.
PMCID: PMC3220645  PMID: 22014337
Crohn's disease; ulcerative colitis; elastography; ultrasound
9.  Pulmonary Venous Anatomy Imaging with Low-Dose, Prospectively ECG-Triggered, High-Pitch 128-Slice Dual Source Computed Tomography 
Efforts to reduce radiation from cardiac computed tomography (CT) are essential. Using a prospectively triggered, high-pitch dual source CT (DSCT) protocol, we aim to determine the radiation dose and image quality (IQ) in patients undergoing pulmonary vein (PV) imaging.
Methods and Results
In 94 patients (61±9 years, 71% male) who underwent 128-slice DSCT (pitch 3.4), radiation dose and IQ were assessed and compared between 69 patients in sinus rhythm (SR) and 25 in atrial fibrillation (AF). Radiation dose was compared in a subset of 19 patients with prior retrospective or prospectively triggered CT PV scans without high-pitch. In a subset of 18 patients with prior magnetic resonance imaging (MRI) for PV assessment, PV anatomy and scan duration were compared to high-pitch CT. Using the high-pitch protocol, total effective radiation dose was 1.4 [1.3, 1.9] mSv, with no difference between SR and AF (1.4 vs 1.5 mSv, p=0.22). No high-pitch CT scans were non-diagnostic or had poor IQ. Radiation dose was reduced with high-pitch (1.6 mSv) compared to standard protocols (19.3 mSv, p<0.0001). This radiation dose reduction was seen with SR (1.5 vs 16.7 mSv, p<0.0001) but was more profound with AF (1.9 vs 27.7 mSv, p=0.039). There was excellent agreement of PV anatomy (kappa 0.84, p<0.0001), and a shorter CT scan duration (6 minutes) compared to MRI (41 minutes, p<0.0001).
Using a high-pitch DSCT protocol, PV imaging can be performed with minimal radiation dose, short scan acquisition, and excellent IQ in patients with SR or AF. This protocol highlights the success of new cardiac CT technology to minimize radiation exposure, giving clinicians a new low-dose imaging alternative to assess PV anatomy.
PMCID: PMC3384510  PMID: 22586259
arrhythmia (Heart Rhythm Disorders); atrial fibrillation; imaging; pulmonary vein isolation; computed tomography
10.  Divergent patterns of total and cancer mortality in ulcerative colitis and Crohn’s disease patients: the Florence IBD study 1978–2001 
Gut  2004;53(9):1309-1313.
Background and aims: Two divergent patterns of mortality for smoking related diseases in ulcerative colitis and Crohn’s disease patients were suggested in a previous population based study in Florence, Italy. Long term follow up (median 15 years) was completed to re-evaluate mortality in this Mediterranean cohort.
Patients and methods: Overall, 920 patients with inflammatory bowel disease were followed until December 2001 or death, with seven patients (0.8%) lost to follow up. A total of 14 040 person years were available for analysis; 118 deaths were observed (81/689 in ulcerative colitis and 37/231 in Crohn’s disease). Expected deaths were estimated using age, sex, and calendar specific national and local mortality rates; standardised mortality ratios (SMR) and 95% confidence interval (CI) were calculated.
Results: Among Crohn’s disease patients, mortality was strongly increased for gastrointestinal diseases (SMR 4.49 (95% CI 1.80–9.25)), all cancers (SMR 2.10 (95% CI 1.22–3.36)), and lung cancer (SMR 4.00 (95% CI 1.60–8.24)), leading to a significant 50% excess total mortality. Ulcerative colitis patients showed a significantly reduced total mortality because of lower cardiovascular (SMR 0.67 (95% CI 0.45–0.95)) and lung cancer (SMR 0.32 (95% CI 0.07–0.95)) mortality. No significant excess for colorectal cancer mortality was evident in this extended follow up.
Conclusions: These clearly divergent patterns of mortality correlate with documented differences in smoking habits between Crohn’s disease and ulcerative colitis patients. Family doctors and gastroenterologists should consider stopping cigarette smoking a specific priority for Crohn’s disease patients; the latter should be offered free participation in structured programmes for smoking cessation, with the aim of reducing smoking related excess mortality. Overall, no evidence of an increased mortality for large bowel cancer emerged in this series.
PMCID: PMC1774198  PMID: 15306591
Crohn’s disease; ulcerative colitis; inflammatory bowel disease; mortality; epidemiology
11.  Cancer Risk in Diagnostic Radiation Workers in Korea from 1996–2002 
This study was aimed to examine the association between the effective radiation dose of diagnostic radiation workers in Korea and their risk for cancer. A total of 36,394 diagnostic radiation workers (159,189 person-years) were included in this study; the effective dose and cancer incidence were analyzed between the period 1996 and 2002. Median (range) follow-up time was 5.5 (0.04–7) years in males and 3.75 (0.04–7) years in females. Cancer risk related to the average annual effective dose and exposure to more than 5 mSv of annual radiation dose were calculated by the Cox proportional hazard model adjusted for occupation and age at the last follow-up. The standardized incidence ratio of cancer in radiation workers showed strong healthy worker effects in both male and female workers. The relative risk of all cancers from exposure of the average annual effective dose in the highest quartile (upper 75% or more of radiation dose) was 2.14 in male workers (95% CI: 1.48–3.10, p-trend: <0.0001) and 4.43 in female workers (95% CI: 2.17–9.04, p-trend: <0.0001), compared to those in the lower three quartiles of radiation exposure dose (less than upper 75% of radiation dose). Cancer risks of the brain (HR: 17.38, 95% CI: 1.05–287.8, p-trend: 0.04) and thyroid (HR: 3.88, 95% CI: 1.09–13.75, p-trend: 0.01) in female workers were significantly higher in the highest quartile group of radiation exposure compared to those in the lower three quartiles, and the risk of colon and rectum cancers in male workers showed a significantly increasing trend according to the increase of the average annual radiation dose (HR: 2.37, 95% CI: 0.99–5.67, p-trend: 0.02). The relative risk of leukemia in male workers and that of brain cancer in female workers were significantly higher in the group of people who had been exposed to more than 5 mSv/year than those exposed to less than 5 mSv/year (HR: 11.75, 95% CI: 1.08–128.20; HR: 63.11, 95% CI: 3.70–1,075.00, respectively). Although the present study involved a relatively young population and a short follow-up time, statistically significant increased risks of some cancers in radiation workers were found, which warrants a longer follow-up study and more intensive protective measures in this population.
PMCID: PMC3564144  PMID: 23343985
cancer risk; diagnostic radiation workers; effective dose
12.  Inflammatory bowel disease in children--clinical, endoscopic, radiologic and histopathologic investigation. 
This paper reviews our five years' clinical experience (1987 to 1991) of 22 patients with inflammatory bowel disease (IBD). There were 12 patients with Crohn's disease and 10 patients with ulcerative colitis. The mean age at diagnosis was 8.7 years (2 to 14 years). Clinical impressions before referral were chronic diarrhea in 11, irritable bowel syndrome in 5, colon polyp in 4, lymphoma in 3, intestinal tuberculosis in 2, amoebic colitis in 2, ulcerative colitis in 2 children and other diseases. The mean interval from the onset of symptoms to the diagnosis of IBD was 18 months. Diagnosis of Crohn's disease was delayed for more than 13 months in 8 (67%), whereas that of ulcerative colitis was delayed for more than 13 months in 4 (40%). Diarrhea (50%), abdominal pain (36%) and rectal bleeding (36%) were the three most frequent presenting complaints of IBD. Moderately severe abdominal pain was a more common chief complaint in Crohn's disease (58%) than in ulcerative colitis (10%). Hematochezia (90% vs 17%) and moderately severe diarrhea (90% vs 75%) were more common gastrointestinal manifestations in ulcerative colitis than in Crohn's disease. The associated extraintestinal manifestations were oral ulcer in 7, arthralgia in 11 and arthritis in 4, skin lesions in 2, eye lesions in 2 and growth failure in 9 patients. Of 12 children with Crohn's disease, granuloma was found in 5, aphthous ulcerations in 8, cobble stone appearance in 8, skip area or asymmetric lesions in 6, transmural involvement in 7, and perianal fistula in 3. Among 10 children with ulcerative Colitis, there were crypt abscess in 8, granularity or friability in 10 and rectosigmoid ulcerations with purulent exudate in 8 children. The main sites of involvement in children with Crohn's disease were both the small and large bowels in 7 (58%), small bowel only in 2 (16%), and colon only in 3 (25%). Terminal ileum involvement was seen in 75% of Crohn's disease cases. The main sites of involvement in children with ulcerative colitis were total colon in 4 (40%), up to the splenic flexure in 2 (20%), rectosigmoid in 3 (30%) and rectum only in one (10%). Medical treatment including sulfasalazine, and systemic or topical steroid was administered initially in most patients. Seven of 12 patients with Crohn's disease and 2 of 10 patients with ulcerative colitis were operated on.(ABSTRACT TRUNCATED AT 400 WORDS)
PMCID: PMC3053786  PMID: 1285921
13.  Cancer risk related to low-dose ionizing radiation from cardiac imaging in patients after acute myocardial infarction 
Patients exposed to low-dose ionizing radiation from cardiac imaging and therapeutic procedures after acute myocardial infarction may be at increased risk of cancer.
Using an administrative database, we selected a cohort of patients who had an acute myocardial infarction between April 1996 and March 2006 and no history of cancer. We documented all cardiac imaging and therapeutic procedures involving low-dose ionizing radiation. The primary outcome was risk of cancer. Statistical analyses were performed using a time-dependent Cox model adjusted for age, sex and exposure to low-dose ionizing radiation from noncardiac imaging to account for work-up of cancer.
Of the 82 861 patients included in the cohort, 77% underwent at least one cardiac imaging or therapeutic procedure involving low-dose ionizing radiation in the first year after acute myocardial infarction. The cumulative exposure to radiation from cardiac procedures was 5.3 milliSieverts (mSv) per patient-year, of which 84% occurred during the first year after acute myocardial infarction. A total of 12 020 incident cancers were diagnosed during the follow-up period. There was a dose-dependent relation between exposure to radiation from cardiac procedures and subsequent risk of cancer. For every 10 mSv of low-dose ionizing radiation, there was a 3% increase in the risk of age- and sex-adjusted cancer over a mean follow-up period of five years (hazard ratio 1.003 per milliSievert, 95% confidence interval 1.002–1.004).
Exposure to low-dose ionizing radiation from cardiac imaging and therapeutic procedures after acute myocardial infarction is associated with an increased risk of cancer.
PMCID: PMC3050947  PMID: 21324846
14.  Thiol methyltransferase activity in inflammatory bowel disease 
Gut  2000;47(2):206-210.
BACKGROUND—Luminal anionic sulphide may contribute to epithelial damage in ulcerative colitis. Thiol methyltransferase (TMT) governs sulphide detoxification by the colonic mucosa and circulating erythrocytes.
AIMS—To measure levels of TMT activity in erythrocytes of surgically treated cases of colitis or in rectal biopsies of defined groups of colitis.
PATIENTS—Venepuncture blood was obtained from 37 blood donors and 27 subjects who had previously undergone a proctocolectomy for colitis: 18 for ulcerative colitis and nine for Crohn's colitis. Rectal biopsies from 122 cases were obtained: 47 without mucosal disease, 33 post-colon resection for cancer, 14 with moderate to severe ulcerative colitis, 15 with quiescent ulcerative colitis, seven with acute Crohn's colitis, and six with radiation proctitis.
METHODS—TMT activity was measured by high performance liquid chromatography with radioactive detection to measure 14C methylmercaptoethanol formation, the reaction product of cell extracts incubated with mercaptoethanol and 14C S-adenosylmethionine.
RESULTS—Erythrocyte TMT activity of surgically treated cases of colitis was significantly elevated (p<0.001) compared with control cases. TMT activity of rectal biopsies was significantly decreased (p<0.02) in acute but not quiescent ulcerative colitis, Crohn's colitis, or radiation colitis.
CONCLUSIONS—Erythrocyte TMT activity was persistently elevated after proctocolectomy for Crohn's disease and ulcerative colitis. No primary defect of TMT activity was found in any case of unoperated colitis but mucosal activity was diminished with disease progression of ulcerative colitis. Studies of genetic control of TMT activity of erythrocytes in inflammatory bowel disease appear worthwhile.

Keywords: thiol methyltransferase; hydrogen sulphide; methylation; ulcerative colitis; Crohn's disease
PMCID: PMC1727999  PMID: 10896911
15.  Inpatient radiation exposure in patients with spinal trauma 
Radiation exposure from medical imaging is an important patient safety consideration; however, patient exposure guidelines and information on cumulative inpatient exposure are lacking.
Trauma patients undergo numerous imaging studies, and spinal imaging confers a high effective dose; therefore, we examined cumulative effective radiation dose in patients hospitalized with spinal trauma. We hypothesized that people with spinal cord injury (SCI) would have higher exposures than those with spine fractures due to injury severity.
Retrospective data were compiled for all patients with spine injuries admitted to a level I trauma center over a 2-year period.
Outcome measures
Injury severity score (ISS) and cumulative radiation exposure were then determined for these patients, including 406 patients with spinal fractures and 59 patients with SCI.
Cumulative effective dose was 45 millisieverts (mSv) in SCI patients, compared to 38 mSv in spinal fracture patients (P = 0.01). Exposure was higher in patients with an ISS over 16 (P = 0.001). Mean exposure in both groups far exceeded the European annual occupational exposure maximum of 20 mSv. More than one-third of patients with SCI exceeded the US occupational maximum of 50 mSv.
Patients with SCI had significantly higher radiation exposure and ISS than those with spine fracture, but the effective dose was globally high. Dose did not correlate with injury severity for patients with SCI. While the benefits of imaging are clear, radiation exposure does involve risk and we urge practitioners to consider cumulative exposure when ordering diagnostic tests.
PMCID: PMC3595958  PMID: 23809525
Imaging studies; Radiation; Ionizing; Radiation risks; Spinal cord injuries; Spinal trauma; Fractures; Computed tomography; Injury severity score
16.  A Quality Assurance Initiative Targeting Radiation Exposure to Neuroscience Patients in the Intensive Care Unit 
The Neurohospitalist  2015;5(1):9-14.
Patients admitted to an intensive care unit (ICU) with a primary neurologic disorder often receive multiple radiation-based diagnostic studies of the head and neck. Although radiation exposure puts them at risk of intracranial and neck tumors, the amount of radiation received is largely unknown.
We sought to accurately collect cumulative radiation exposure data from radiation-based studies in a retrospective cohort of patients admitted to the neuroscience ICU (NICU) at a single institution. Radiation doses of studies were converted to estimated effective doses in mSv via literature-published formulas. To impact ordering practices, we piloted an educational initiative on patient radiation exposure to a cohort of physicians caring for patients with a diagnosis of acute subarachnoid hemorrhage. Patients were randomized to have radiation exposure data posted at the bedside for physician viewing.
We identified 641 patients from July 2010 to March 2011 who had received at least 1 computed tomography-based study of the head. Patients received on average 18.4 mSv of radiation from head and neck imaging. Patients with subarachnoid hemorrhage received the highest average levels of radiation exposure (37.1 mSv). Attributable risk of carcinogenesis was estimated to be low. A pilot educational initiative did not reduce the total estimated effective dose per patient.
Accurate reporting of estimated effective doses for NICU patients is feasible and can be provided to ordering physicians to assist with clinical decision making and potentially lower exposure risk. Further strategies are needed to reduce unnecessary radiation exposure at the physician ordering level.
PMCID: PMC4272353  PMID: 25553223
cerebral angiography/adverse effects; cranial irradiation/adverse effects; intensive care units; neuroradiography; radiation dosage; radiation injuries/prevention & control; risk assessment; subarachnoid hemorrhage/radiography
17.  Use of Diagnostic Imaging Studies and Associated Radiation Exposure For Patients Enrolled in Large Integrated Healthcare Systems, 1996–2010 
JAMA : the journal of the American Medical Association  2012;307(22):10.1001/jama.2012.5960.
Diagnostic imaging use increased significantly within fee-for-service models of care. Little is known about patterns of imaging among members of integrated health care systems.
To estimate trends in imaging utilization and associated radiation exposure among members of integrated healthcare systems.
Design, Setting, and Participants
Retrospective analysis of electronic records of members of six large integrated health systems from diverse regions of the country. Review of medical records allowed direct estimation of radiation exposure from selected tests. Between 1–2 million member-patients were included each year from 1996 to 2010.
Main Outcome Measure
Advanced diagnostic imaging rates, and cumulative annual radiation exposure from medical imaging.
During the 15 year study period, enrollees underwent a total of 30.9 million imaging examinations (over 25.9 million person-years), reflecting 1.18 (95% CI 1.17–1.19) tests per person per year, of which 35% were for advanced diagnostic imaging (CT, MRI, nuclear medicine, and ultrasound). Use of advanced diagnostic imaging increased from 1996 to 2010; computed tomography examinations increased from 52/1000 enrollees in 1996 to 149/1000 in 2010, 7.8% annual growth (95% CI 5.8%, 9.8%); MRI increased from 17/1000 to 65/1000, 10% annual growth (95% CI 3.3%, 16.5%); and ultrasound increased from 134/1000 to 230/1000, 3.9% annual growth (95% CI 3.0% to 4.9%). While nuclear medicine decreased from 32/1000 to 21/1000, 3% annual decline (95% CI 7.7% decline to 1.3% increase), after 2004, PET imaging rates increased from 2.2/10 000 to 23.5/10 000, 15.2% annual growth. While imaging increased within all health systems, the adoption of different modalities for anatomic area assessment varied. Increased use of CT resulted in increased radiation exposure for enrollees, with a doubling in the mean per capita effective dose and in the proportion of enrollees who received high (>20–50 mSv) or very high (>50mSv) annual radiation exposure. By 2010, nearly 7% of enrollees who underwent imaging received a high annual radiation exposure (>20–50 mSv) and 4% received a very high annual exposure (>50 mSv).
Within integrated health care systems there was a large increase in the rate of advanced diagnostic imaging and associated radiation exposure between 1996 and 2010.
PMCID: PMC3859870  PMID: 22692172
18.  Radiation Exposure from Diagnostic Procedures following Allogeneic Stem Cell Transplantation – How Much Is Acceptable? 
Patients receiving allogeneic stem cell transplants (SCT) can remain acutely sick for many weeks and incur repeated diagnostic radiology procedures which may significantly increase radiation exposure. This retrospective cohort study was conducted to determine the cumulative radiation dose from diagnostic studies following SCT. Sixty-four consecutive patients with hematologic malignancies in a single tertiary care institution underwent total body irradiation-based myeloablative conditioning followed by 6/6 HLA-identical sibling allogeneic stem cell transplantation. The median follow up was three years. The cumulative effective dose in mSv from diagnostic radiologic studies in the peri-transplant period from day −30 to day +200 was calculated for each patient and its impact on overall survival and nonrelapse mortality was determined. The median cumulative radiation exposure from diagnostic radiologic procedures was 92 mSv (range 1.2–300), representing about 30× the normal annual background radiation for the population and 10% of the 1200cGy total body irradiation (TBI) dose used in conditioning. Sixty-five percent of the cumulative radiation exposure was delivered between day +1 and day 100 and CT scans contributed 88%. While radiation exposure from diagnostic procedures did not impact clinical outcomes the risk of second cancers in long term survivors is likely to be increased. Our results indicate that patients who are acutely ill for prolonged periods can receive clinically significant radiation doses during their hospital care. Our findings should prompt attempts to limit radiation exposure from diagnostic procedures in post-SCT recipients.
PMCID: PMC4155497  PMID: 24094072
HSCT; diagnostic; radiation; CT; outcome
19.  Cost of illness of inflammatory bowel disease in the UK: a single centre retrospective study 
Gut  2004;53(10):1471-1478.
Background and aims: The potentially high costs of care associated with inflammatory bowel disease (IBD) are recognised but we have little knowledge of the scale, profile, or determinants of these costs in the UK. This study aimed to describe costs of illness for a group of IBD patients and determine factors associated with increased healthcare costs.
Setting: A university hospital serving a target population of approximately 330 000.
Patients and methods: A six month cohort of IBD patients receiving any form of secondary care was identified, comprising 307 cases of ulcerative (or indeterminate) colitis and 172 cases of Crohn’s disease. Demographic and clinical data were abstracted from clinical records and individual resource use was itemised for all attributable costs (including extraintestinal manifestations). Item costs were derived from national and local sources. Cost data were expressed as mean six month costs per patient (with 95% confidence interval (CI)) obtained using non-parametric bootstrapping. Determinants of cost were analysed using generalised linear regression modelling. A postal survey of patients was undertaken to examine indirect costs, out of pocket expenses, and primary care visits.
Results: Inpatient services (medical and/or surgical) were required by 67 patients (14%) but accounted for 49% of total secondary care costs. Drug costs accounted for less than a quarter of total costs. Individual patient costs ranged from £73 to £33 254 per six months. Mean (95% CI) six month costs per patient were £1256 (£988, £1721) for colitis and £1652 (£1221, £2239) for Crohn’s disease. Hospitalisation, disease severity grade, and disease extent correlated positively with cost of illness but costs were independent of age or sex. Compared with quiescent cases of IBD, disease relapse was associated with a 2–3-fold increase in costs for non-hospitalised cases and a 20-fold increase in costs for hospitalised cases. Survey data suggested average six month costs were <£30 per patient for primary care visits (both diseases) and median loss of earnings were £239 for colitis and £299 for Crohn’s disease.
Conclusions: This study represents the first detailed characterisation of the scale and determinants of costs of illness for IBD in a British hospital. Hospitalisation affected a minority of sufferers but accounted for half of the total direct costs falling on the healthcare system.
PMCID: PMC1774248  PMID: 15361497
inflammatory bowel disease; ulcerative colitis; Crohn’s disease; costs; economics
20.  Pediatric Hodgkin Lymphoma: Are We Over-Scanning Our Patients? 
Pediatric hematology and oncology  2012;29(5):415-423.
Despite the favorable outcome of most pediatric patients with Hodgkin lymphoma (HL), there is rising concern about risks of carcinogenesis from both diagnostic and therapeutic radiation exposure for patients treated on study protocols. Although previous studies have investigated radiation exposure during treatment, radiation from post-treatment surveillance imaging may also increase the likelihood of secondary malignancies. All diagnostic imaging examinations involving ionizing radiation exposure performed for surveillance following completion of therapy were recorded for 99 consecutive pediatric patients diagnosed with HL from 2000 to 2010. Cumulative radiation dosage from these examinations and the frequency of relapse detection by these examinations were recorded. In the first 2 years following completion of therapy, patients in remission received a median of 11 examinations (range 0–26). Only 13 of 99 patients relapsed, 11 within 5 months of treatment completion. No relapse was detected by 1- or 2-view chest radiographs (n = 38 and 296, respectively), abdomen/pelvis computed tomography (CT) scans (n = 211), or positron emission tomography (PET) scans alone (n = 11). However, 10/391 (2.6%) of chest CT scans, 4/364 (1.1%) of neck CT scans, and 3/47 (6.4%) of PET/CT scans detected relapsed disease. Thus, only 17 scans (1.3%) detected relapse in a total of 1358 scans. Mean radiation dosages were 31.97 mSv for Stage 1, 37.76 mSv for Stage 2, 48.08 mSv for Stage 3, and 51.35 mSv for Stage 4 HL. Approximately 1% of surveillance imaging examinations identified relapsed disease. Given the very low rate of relapse detection by surveillance imaging stipulated by current protocols for pediatric HL patients, the financial burden of the tests themselves, the high cure rate, and risks of second malignancy from ionizing radiation exposure, modification of the surveillance strategy is recommended.
PMCID: PMC3685486  PMID: 22632168
Hodgkin disease; late effects; radiology
Computed tomography (CT) radiation exposure has come under increasing scrutiny due to dramatically increased utilization. Multiphase CT studies (repeated scanning before and after contrast injection) are potentially important, overlooked source of medically unnecessary radiation due to the dose-multiplier effect of extra phases. The purpose of this study is to determine the frequency of unindicated multiphase scanning and resultant excess radiation exposure in a sample referral population.
This study was IRB approved and HIPAA compliant. Abdomen/pelvis CT exams (n=500) performed at outside institutions submitted for tertiary interpretation were retrospectively reviewed for 1) appropriateness of each phase based on clinical indication and American College of Radiology (ACR) Appropriateness Criteria, and 2) per phase and total radiation effective dose.
A total of 978 phases were performed in 500 patients, 52.8% (264/500) received phases that were not supported by ACR criteria. Overall, 35.8% (350/978) of phases were unindicated, most commonly being delayed imaging (272/350). The mean overall total radiation effective dose per patient was 25.8 mSv (95% CI 24.2, 27.5 mSv). Mean effective dose for unindicated phases was 13.1 (12.3, 14.0) mSv, resulting in a mean excess effective dose of 16.8 (15.5, 18.3) mSv per patient. Unindicated radiation comprised 33.3% of the total radiation effective dose in this population. Radiation effective doses exceeding 50 mSv were found in 21.2% (106/500) of patients.
The results of this study suggest that a large proportion of patients undergoing abdominal/pelvic CT scanning receive unindicated additional phases that add substantial excess radiation dose with no associated clinical benefit.
PMCID: PMC4131253  PMID: 22051457
22.  Computed Tomography Enterography for Evaluation of Inflammatory Bowel Disease 
Clinical Endoscopy  2013;46(4):327-366.
Computed tomography enterography (CTE) has become a main modality for the evaluation of inflammatory bowel disease (IBD). It simultaneously offers visualization of the small bowel and extraintestinal status, which is helpful for diagnosing IBD. Crohn disease has long segmental enhancing wall thickening related with the eccentric longitudinal distribution. In addition, mural stratification, fibrofatty proliferation, positive comb sign by increased mesenteric vascularity and internal/perianal fistula are characteristics of Crohn disease and can be identified on CTE. Short segmental inflammatory wall thickening and the central low attenuated lymph nodes are favorable CT finding of intestinal tuberculosis. A geographic, relatively large, and deep penetrating ulcer with bowel wall thickening and mural hyperenhancement in ileocecal area are characteristics of intestinal Behcet disease. Each of CTE findings for the IBDs is helpful for differential diagnosis. The main disadvantage of this technique is the requisite radiation exposure of patients, particularly in young patients. However, recent development of advanced CT techniques is promising for radiation dose reduction without compromising diagnostic image quality.
PMCID: PMC3746137  PMID: 23964329
Computed tomography enterography; Inflammatory bowel diseases; Crohn disease; Intestinal tuberculosis; Behcet syndrome
23.  Coronary CTA using scout-based automated tube potential and current selection algorithm, with breast displacement results in lower radiation exposure in females compared to males 
To evaluate the effect of automatic tube potential selection and automatic exposure control combined with female breast displacement during coronary computed tomography angiography (CCTA) on radiation exposure in women versus men of the same body size.
Materials and methods
Consecutive clinical exams between January 2012 and July 2013 at an academic medical center were retrospectively analyzed. All examinations were performed using ECG-gating, automated tube potential, and tube current selection algorithm (APS-AEC) with breast displacement in females. Cohorts were stratified by sex and standard World Health Organization body mass index (BMI) ranges. CT dose index volume (CTDIvol), dose length product (DLP) median effective dose (ED), and size specific dose estimate (SSDE) were recorded. Univariable and multivariable regression analyses were performed to evaluate the effect of gender on radiation exposure per BMI.
A total of 726 exams were included, 343 (47%) were females; mean BMI was similar by gender (28.6±6.9 kg/m2 females vs. 29.2±6.3 kg/m2 males; P=0.168). Median ED was 2.3 mSv (1.4-5.2) for females and 3.6 (2.5-5.9) for males (P<0.001). Females were exposed to less radiation by a difference in median ED of –1.3 mSv, CTDIvol –4.1 mGy, and SSDE –6.8 mGy (all P<0.001). After adjusting for BMI, patient characteristics, and gating mode, females exposure was lower by a median ED of –0.7 mSv, CTDIvol –2.3 mGy, and SSDE –3.15 mGy, respectively (all P<0.01).
Conclusions: We observed a difference in radiation exposure to patients undergoing CCTA with the combined use of AEC-APS and breast displacement in female patients as compared to their BMI-matched male counterparts, with female patients receiving one third less exposure.
PMCID: PMC4278037  PMID: 25610804
Coronary computed tomography angiography (CCTA); female; breast displacement; radiation exposure
24.  Diagnostic Ionizing Radiation Exposure in a Population-based Sample of Children with Inflammatory Bowel Diseases 
Background and Aims
The degree of diagnostic radiation exposure in children with inflammatory bowel diseases (IBD) is largely unknown. Here we describe this exposure in a population-based sample of children with IBD and determine characteristics associated with moderate radiation exposure.
We ascertained radiological study use, demographic characteristics, IBD medication use, and the requirement for hospitalization, emergency department (ED) encounter, or inpatient GI surgery among children with IBD within a large insurance claims database. Characteristics associated with moderate radiation exposure (at least one computed tomography (CT) or three fluoroscopies over two years) were determined using logistic regression models.
We identified 965 children with Crohn’s Disease (CD) and 628 with Ulcerative Colitis (UC). Over 24 months, 34% of CD subjects and 23% of UC subjects were exposed to moderate diagnostic radiation [odds ratio (OR) 1.71, 95% confidence interval (CI), 1.36–2.14]. CT accounted for 28% and 25% of all studies in CD and UC subjects, respectively. For CD subjects, moderate radiation exposure was associated with hospitalization (OR 4.89, 95% CI 3.37–7.09), surgery (OR 2.93, 95% CI 1.59–5.39), ED encounter (OR 2.65, 1.93–3.64 95% CI), oral steroids (OR 2.25, 95% CI 1.50–3.38), and budesonide (OR 1.80, 95% CI 1.10–3.06); an inverse association was seen with immunomodulator use (OR 0.67, 95% CI 0.47–0.97). Except for oral steroids and immunomodulators, similar relationships were seen in UC.
A substantial proportion of children with IBD are exposed to moderate amounts of radiation as a result of diagnostic testing. This high utilization may impart long-term risk given the chronic nature of the disease.
PMCID: PMC2788488  PMID: 19690524
25.  Coronary computed tomography angiography with model-based iterative reconstruction using a radiation exposure similar to chest X-ray examination 
European Heart Journal  2014;35(17):1131-1136.
To evaluate the feasibility and image quality of coronary computed tomography angiography (CCTA) acquisition with a submillisievert fraction of effective radiation dose using model-based iterative reconstruction (MBIR) for noise reduction.
Methods and results
In 42 patients undergoing standard low-dose (100–120 kV; 450–700 mA) and additional ultra-low-dose CCTA (80–100 kV; 150–210 mA) reconstructed with MBIR, segmental image quality was graded on a four-point scale [(i): non-evaluative, (ii): good, (iii): adequate, and (iv): excellent]. Signal-to-noise ratio (SNR) was calculated dividing left main artery (LMA) and right coronary artery (RCA) attenuation by the aortic root noise. Over a wide range of body mass index (18–40 kg/m2), the estimated median radiation dose exposure was 1.19 mSv [interquartile range (IQR): 1.07–1.30 mSv] for standard and 0.21 mSv (IQR: 0.18–0.23 mSv) for ultra-low-dose CCTA (P < 0.001). The median image quality score per segment was 3.5 (IQR: 3.0–4.0) in standard CCTA vs. 3.5 (IQR: 2.5–4.0) in ultra-low dose with MBIR (P = 0.29). Diagnostic image quality (scores 2–4) was found in 98.7 vs. 97.8% coronary segments (P = 0.36). Introduction of MBIR for ultra-low-dose CCTA resulted in a significant increase in SNR (P < 0.001) for LMA (from 15 ± 5 to 29 ± 7) and RCA (from 14 ± 4 to 27 ± 6) despite 82% dose reduction.
Coronary computed tomography angiography acquisition with diagnostic image quality is feasible at an ultra-low radiation dose of 0.21 mSv, e.g. in the range reported for a postero-anterior and lateral chest X-ray.
PMCID: PMC4006092  PMID: 24553723
Ultra-low-dose coronary computed tomography angiography; Model-based iterative reconstruction; Feasibility

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