Reducing radiation dose in CT enterography

Diagnostic performance and image quality of an image-based denoising algorithm applied to radiation dose-reduced CT in diagnosing acute appendicitis

PURPOSE

To evaluate diagnostic performance and image quality of ultralow-dose CT (ULDCT) in diagnosing acute appendicitis with an image-based deep-learning denoising algorithm (IDLDA).

METHODS

This retrospective multicenter study included 180 patients (mean ± standard deviation, 29 ± 9 years; 91 female) who underwent contrast-enhanced 2-mSv CT for suspected appendicitis from February 2014 to August 2016. We simulated ULDCT from 2-mSv CT, reducing the dose by at least 50%. Then we applied an IDLDA on ULDCT to produce denoised ULDCT (D-ULDCT). Six radiologists with different experience levels (three board-certified radiologists and three residents) independently reviewed the ULDCT and D-ULDCT. They rated the likelihood of appendicitis and subjective image qualities (subjective image noise, diagnostic acceptability, and artificial sensation). One radiologist measured image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). We used the receiver operating characteristic (ROC) analyses, Wilcoxon's signed-rank tests, and paired t-tests.

RESULTS

The area under the ROC curves (AUC) for diagnosing appendicitis ranged 0.90-0.97 for ULDCT and 0.94-0.97 for D-ULDCT. The AUCs of two residents were significantly higher on D-ULDCT (AUC difference = 0.06 [95% confidence interval, 0.01-0.11; p = .022] and 0.05 [0.00-0.10; p = .046], respectively). D-ULDCT provided better subjective image noise and diagnostic acceptability to all six readers. However, the response of board-certified radiologists and residents differed in artificial sensation (all p ≤ .003). D-ULDCT showed significantly lower image noise, higher SNR, and higher CNR (all p < .001).

CONCLUSION

An IDLDA can provide better ULDCT image quality and enhance diagnostic performance for less-experienced radiologists.

Automatic Segmentation and Radiomics for Identification and Activity Assessment of CTE Lesions in Crohn's Disease

BACKGROUND

The purpose of this article is to develop a deep learning automatic segmentation model for the segmentation of Crohn's disease (CD) lesions in computed tomography enterography (CTE) images. Additionally, the radiomics features extracted from the segmented CD lesions will be analyzed and multiple machine learning classifiers will be built to distinguish CD activity.

METHODS

This was a retrospective study with 2 sets of CTE image data. Segmentation datasets were used to establish nnU-Net neural network's automatic segmentation model. The classification dataset was processed using the automatic segmentation model to obtain segmentation results and extract radiomics features. The most optimal features were then selected to build 5 machine learning classifiers to distinguish CD activity. The performance of the automatic segmentation model was evaluated using the Dice similarity coefficient, while the performance of the machine learning classifier was evaluated using the area under the curve, sensitivity, specificity, and accuracy.

RESULTS

The segmentation dataset had 84 CTE examinations of CD patients (mean age 31 ± 13 years , 60 males), and the classification dataset had 193 (mean age 31 ± 12 years , 136 males). The deep learning segmentation model achieved a Dice similarity coefficient of 0.824 on the testing set. The logistic regression model showed the best performance among the 5 classifiers in the testing set, with an area under the curve, sensitivity, specificity, and accuracy of 0.862, 0.697, 0.840, and 0.759, respectively.

CONCLUSION

The automated segmentation model accurately segments CD lesions, and machine learning classifier distinguishes CD activity well. This method can assist radiologists in promptly and precisely evaluating CD activity.

Image quality and diagnostic accuracy of reduced-dose computed tomography enterography with model-based iterative reconstruction in pediatric Crohn's disease patients

This study assessed the image quality and diagnostic accuracy in determining disease activity of the terminal ileum of the reduced-dose computed tomography enterography using model-based iterative reconstruction in pediatric patients with Crohn's disease (CD). Eighteen patients were prospectively enrolled and allocated to the standard-dose (SD) and reduced-dose (RD) computed tomography enterography (CTE) groups (n = 9 per group). Image quality, reader confidence in interpreting bowel findings, accuracy in determining active CD in the terminal ileum, and radiation dose were evaluated. Objective image quality did not show intergroup differences, except for image sharpness. Although reader confidence in detecting mural stratification, ulcer, and perienteric fat stranding of the RD-CTE were inferior to SD-CTE, RD-CTE correctly diagnosed active disease in all patients. The mean values of radiation dose metrics (SD-CTE vs. RD-CTE) were 4.3 versus 0.74 mGy, 6.1 versus 1.1 mGy, 211.9 versus 34.5 mGy∙cm, and 4.4 versus 0.7 mSv mGy∙cm for CTDI_vol, size-specific dose estimation, dose-length product, and effective dose, respectively. RD-CTE showed comparable diagnostic accuracy to SD-CTE in determining active disease of the terminal ileum in pediatric CD patients. However, image quality and reader confidence in detecting ulcer and perienteric fat stranding was compromised.

COMPARATIVE ANALYSIS OF TWO ORAL CONTRAST AGENT VOLUMES FOR COMPUTED TOMOGRAPHY ENTEROGRAPHY IN CROHN'S DISEASE PATIENTS

BACKGROUND

Crohn's disease (CD) is an inflammatory bowel disease characterized by a chronic and recurrent inflammation of the gastrointestinal tract caused by an interaction of genetic and environmental factors.

OBJECTIVE

To compare the quality and acceptance of two different oral contrast volumes for computed tomography enterography in Crohn's disease patients.

METHODS

A cross-sectional study was conducted in 58 consecutive Crohn's disease patients who randomly received an oral contrast agent composed of 78.75 g polyethylene glycol diluted in either 1,000 mL or 2,000 mL of water. An examination was performed to evaluate the presence of inflammation or complications in the small bowel. The variables included the quality of intestinal segment filling and luminal distension, and oral contrast agent acceptance and tolerance in the patients. Statistical analysis included descriptive statistics and association tests.

RESULTS

A total of 58 patients were assessed, in which 58.6% were female, 34.5% exhibited clinically-active disease, and 63.8% were receiving biologic therapy. As for comparative analysis between the two different volumes of oral contrast, no statistically significant difference was found regarding bowel loop filling (P=0.58) and adequate luminal distension (P=0.45). Patients who received a larger volume (2,000 mL) exhibited side-effects more frequently (51.7% vs 31.0%; P=0.06) and had greater difficulty ingesting the agent (65.5% vs 37.9%; P=0.07) compared with a volume of 1,000 mL.

CONCLUSION

The quality of computed tomography enterography was not influenced by the contrast volume. However, acceptance and tolerance were better in the 1,000 mL group.

Iron Deficiency and the Small bowel​

PURPOSE OF REVIEW

This article reviews iron deficiency anemia (IDA) and suspected small bowel bleeding (SSBB) from initial consultation through laboratory evaluation, endoscopic evaluation, and therapeutic options.

RECENT FINDINGS

Recent guidelines on management of SSBB, IDA, video capsule endoscopy (VCE), and device-assisted enteroscopy (DAE) are reviewed. The advantages and limitations of VCE, DAE, and imaging are discussed. Medical treatment for refractory small bowel bleeding is discussed. Evaluation of IDA starts with a detailed history and physical exam. Additional lab work can establish the diagnosis of IDA and evaluate for associated conditions. If initial endoscopic tests are unrevealing, SSBB should be ruled out. Further investigation can be performed using video capsule endoscopy (VCE), device-assisted enteroscopy (DAE), and imaging. The mainstay of medical treatment of IDA secondary to SSBB is iron supplementation. Additional treatment is tailored to the pathology and may include medical, endoscopic and surgical options.

Radiation exposure during the treatment of spinal deformities

AIMS

To benchmark the radiation dose to patients during the course of treatment for a spinal deformity.

METHODS

Our radiation dose database identified 25,745 exposures of 6,017 children (under 18 years of age) and adults treated for a spinal deformity between 1 January 2008 and 31 December 2016. Patients were divided into surgical (974 patients) and non-surgical (5,043 patients) cohorts. We documented the number and doses of ionizing radiation imaging events (radiographs, CT scans, or intraoperative fluoroscopy) for each patient. All the doses for plain radiographs, CT scans, and intraoperative fluoroscopy were combined into a single effective dose by a medical physicist (milliSivert (mSv)).

RESULTS

There were more ionizing radiation-based imaging events and higher radiation dose exposures in the surgical group than in the non-surgical group (p < 0.001). The difference in effective dose for children between the surgical and non-surgical groups was statistically significant, the surgical group being significantly higher (p < 0.001). This led to a higher estimated risk of cancer induction for the surgical group (1:222 surgical vs 1:1,418 non-surgical). However, the dose difference for adults was not statistically different between the surgical and non-surgical groups. In all cases the effective dose received by all cohorts was significantly higher than that from exposure to natural background radiation.

CONCLUSION

The treatment of spinal deformity is radiation-heavy. The dose exposure is several times higher when surgical treatment is undertaken. Clinicians should be aware of this and review their practices in order to reduce the radiation dose where possible. Cite this article: Bone Joint J 2021;103-B(4):1-7.

Dual-source abdominopelvic computed tomography: Comparison of image quality and radiation dose of 80 kVp and 80/150 kVp with tin filter

Objective

To compare the radiation dose and the objective and subjective image quality of 80 kVp and 80/150 kVp with tin filter (80/Sn150 kVp) computed tomography (CT) in oncology patients.

Methods

One-hundred-and-forty-five consecutive oncology patients who underwent third-generation dual-source dual-energy CT of the abdomen for evaluation of malignant visceral, peritoneal, extraperitoneal, and bone tumor were retrospectively recruited. Two radiologists independently reviewed each observation in 80 kVp CT and 80/Sn150 kVp CT. Modified line-density profile of the tumor and contrast-to-noise ratio (CNR) were measured. Diagnostic confidence, lesion conspicuity, and subjective image quality were calculated and compared between image sets. The effective dose and size-specific dose estimate (SSDE) were calculated in the image sets.

Results

Modified line-density profile analysis revealed higher attenuation differences between the tumor and normal tissue in 80 kVp CT than in 80/Sn150 kVp CT (127 vs. 107, P = 0.05). The 80 kVp CT showed increased CNR in the liver (8.0 vs. 7.6) and the aorta (18.9 vs. 16.3) than the 80/Sn150 kVp CT. The 80 kVp CT yielded higher enhancement of organs (4.9 ± 0.2 vs. 4.7 ± 0.4, P<0.001) and lesion conspicuity (4.9 ± 0.3 vs. 4.8 ± 0.5, P = 0.035) than the 80/Sn150 kVp CT; overall image quality and confidence index were comparable. The effective dose was reduced by 45.2% with 80 kVp CT (2.3 mSv ± 0.9) compared to 80/Sn150 kVp CT (4.1 mSv ± 1.5). The SSDE was 7.4 ± 3.8 mGy on 80/Sn150 kVp CT and 4.1 ± 2.2 mGy on 80 kVp CT.

Conclusions

The 80 kVp CT reduced the radiation dose by 45.2% in oncology patients while showing comparable or superior image quality to that of 80/Sn150 kVp CT for abdominal tumor evaluation.

Evaluation of Low-Dose Multidetector Computed Tomography Whole Gastroenterography With Oral Administration of Contrast Agents

PURPOSE

To evaluate the degree of gastric, enteric, colonic, and rectal filling in multidetector computed tomography (MDCT) whole gastroenterography.

METHODS

In this prospective study involving 124 patients, 78 and 46 patients underwent MDCT whole gastroenterography using positive and neutral oral contrast agents, respectively. The degree of filling of the stomach, small and large bowel, was qualitatively analyzed by experienced radiologists using a 3-point scoring system.

RESULTS

The majority of patients received a score of ≥2 for small intestine filling using both positive and neutral contrast agents (90.5% and 78.2%, respectively), and <9% of the patients had a score of 0. The highest score for the degree of filling in the small intestine was observed in the ileum, followed by the duodenum and jejunum. There was a significant difference in the degree of filling achieved with positive and neutral contrast agents in the duodenum (P = .013) and jejunum (P = .047). More than 74% of cases had an optimal filling of the stomach, whereas >80% of the cases had an optimal filling of the colorectal segments. Only ≤5.1% had a score of 0 for the analyzed segments of the colorectum. Positive and neutral contrast agents were associated with similar degree of filling in the stomach and colon segments without a significant difference in the extent of contrast agent filling (P > .05).

CONCLUSIONS

Multidetector computed tomography whole gastroenterography was found to be a simple, safe, noninvasive, painless, and effective modality for the diagnosis of stomach and bowel complications in clinical settings.

Feasibility of thin-slice abdominal CT in overweight patients using a vendor neutral image-based denoising algorithm: Assessment of image noise, contrast, and quality

The purpose of this study was to investigate whether the novel image-based noise reduction software (NRS) improves image quality, and to assess the feasibility of using this software in combination with hybrid iterative reconstruction (IR) in image quality on thin-slice abdominal CT. In this retrospective study, 54 patients who underwent dynamic liver CT between April and July 2017 and had a body mass index higher than 25 kg/m² were included. Three image sets of each patient were reconstructed as follows: hybrid IR images with 1-mm slice thickness (group A), hybrid IR images with 5-mm slice thickness (group B), and hybrid IR images with 1-mm slice thickness denoised using NRS (group C). The mean image noise and contrast-to-noise ratio relative to the muscle of the aorta and liver were assessed. Subjective image quality was evaluated by two radiologists for sharpness, noise, contrast, and overall quality using 5-point scales. The mean image noise was significantly lower in group C than in group A (p < 0.01), but no significant difference was observed between groups B and C. The contrast-to-noise ratio was significantly higher in group C than in group A (p < 0.01 and p = 0.01, respectively). Subjective image quality was also significantly higher in group C than in group A (p < 0.01), in terms of noise and overall quality, but not in terms of sharpness and contrast (p = 0.65 and 0.07, respectively). The contrast of images in group C was greater than that in group A, but this difference was not significant. Compared with hybrid IR alone, the novel NRS combined with a hybrid IR could result in significant noise reduction without sacrificing image quality on CT. This combined approach will likely be particularly useful for thin-slice abdominal CT examinations of overweight patients.

Application of Adaptive Statistical Iterative Reconstruction-V With Combination of 80 kV for Reducing Radiation Dose and Improving Image Quality in Renal Computed Tomography Angiography for Slim Patients

OBJECTIVES

To explore the application of adaptive statistical iterative reconstruction-V (ASIR-V) with combination of 80 kV for reducing radiation dose and improving image quality in renal computed tomography angiography (CTA) for slim patients compared with traditional filtered back projection (FBP) reconstruction using 120 kV.

METHODS

Eighty patients for renal CTA were prospectively enrolled and randomly divided into group A and group B. Group A used 120 kV and 600 mgI/kg contrast agent and FBP reconstruction, while group B used 80 kV and 350 mgI/kg contrast agent and both FBP and ASIR-V reconstruction from 10%ASIR-V to 100%ASIR-V with 10%ASIR-V interval. The CT values and SD values of the right renal artery and left renal artery were measured to calculate the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). The image quality was subjectively scored by two experienced radiologists blindly using a five-point criterion. The contrast agent, volumetric CT dose index (CTDI_vol), and dose length product in both groups were recorded and the effective radiation dose was calculated.

RESULTS

There were no significant difference in patient characteristics between two groups (p > 0.05). The CTDI_vol, dose length product and effective radiation dose in group B were 59.0%, 65.0%, and 65.1% lower than those in group A, respectively (all p < 0.05), and the contrast agent in group B was 42.2% lower than that in group A (p < 0.05). In group B, with the increase of ASIR-V percentage, CT values showed no significant difference, SD values decreased gradually, SNR values and CNR values increased gradually. The CT values showed no statistically significant difference (p > 0.05) between two groups with different reconstructions. The SD values with 40%ASIR-V to 100%ASIR-V reconstruction in group B was significantly lower(p < 0.5), while the SNR values with 50% ASIR-V to 100% ASIR-V reconstruction and CNR values with 70%ASIR-V to 100%ASIR-V were significantly higher than those of group A with FBP reconstruction (p < 0.5). Two radiologists had excellent consistency in subjective scores of image quality for renal CTA (kappa >0.75, p < 0.05). The subjective scores with 60% ASIR-V to 90% ASIR-V in group B were significantly higher than those of FBP in group A (p < 0.5), of which 70%ASIR-V reconstruction obtained the highest subjective score for renal CTA.

CONCLUSION

ASIR-V with combination of 80 kV can significantly reduce effective radiation dose (about 65.1%) and contrast agent (about 42.2%) and improve image quality in renal CTA for slim patients compared with traditional FBP reconstruction using 120 kV, and the 70% ASIR-V was the best reconstruction algorithm in 80 kV renal CTA.

ADVANCES IN KNOWLEDGE

Using 80 kV with combination of ASIR-V can significantly reduce radiation dose and contrast agent dose as well as improve image quality in renal CTA for thin patients when compared with FBP using 120 kV.

Automatic current selection with iterative reconstruction reduces effective dose to less than 1 mSv in low-dose chest computed tomography in persons with normal BMI

Most of the recent studies have used fixed tube current while few investigators use automatic current selection (ACS) with iterative reconstruction (IR) techniques to reduce effective dose (ED) to < 1 mSv in low-dose chest computed tomography (LDCCT). We investigated whether image quality of lungs as produced by a fixed tube current (FTC) of 35 mAs can be maintained with ED < 1 mSv produced by ACS with IR techniques in LDCCT. A total of 32 participants were included. The LDCCT was performed by a FTC 35 mAs (with a kilovoltage peak of 120 kVp) in 16 participants (Group A), and by a DoseRight ACS in 16 participants (Group B). Their images were improved by IR technique. The ED was estimated by multiplying the individual dose length product (DLP) by the dose conversion factor. The image quality was assessed by the CT number, noise levels, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) of the regions of interest in the apex, upper lobe, and lower lobe of lung regions in the CT images. A t-test was used to evaluate the LDCCT image quality between the groups. The ED was significantly 49.2% lower in Group B than in Group A (0.71 ± 0.05 mSv vs 1.40 ± 0.02 mSv, P < .001). However, noise level, SNR, and CNR were not significantly different between Groups A and B, indicating the image quality was similar between two groups, or our setting parameters for DoseRight ACS with IR technique can achieve the image quality as good as obtained on the FTC 35 mAs with IR techniques. Our results suggest that the DoseRight ACS with IR technique reduces ED to lower than 1 mSv (averagely 0.71 mSv) yet maintains an image quality as good as produced by FTC 35 mAs with IR technique in normal BMI persons. The ACS setup thus is more preferable than the FTC to achieve the ALARA (as low as reasonably achievable) principle.

Multi-detector CT enterography in active inflammatory bowel disease: Image quality and diagnostic efficacy of a low-radiation high contrast protocol

PURPOSE

To prospectively evaluate image quality and diagnostic efficacy of a low radiation-high contrast (LR-HC) CT Enterography (CTE) in active Inflammatory Bowel Disease (IBD).

MATERIALS AND METHODS

Eighty-five (36M; 49F; 17-75 yrs) patients with active IBD underwent contrast-enhanced CTE and were stratified in two groups according to age (< or ≥45 yrs): Group A (N = 45; 32 ± 9 yrs; 58 ± 10 kg) and Group B (N = 40; 58 ± 10 yrs; 61 ± 13 kg). Each group received a different amount of radiation (Noise Index, NI) and non-ionic iodinated contrast media (LOCM) as follows: Group A (NI = 15; 2.5 ml/kg) and Group B (NI = 12.5; 2 ml/kg). Thyroid functional tests were performed in all patients of group A at 4-6 wks. Signal- and contrast-to-noise ratios were calculated for liver (L) and abdominal aorta (A). Statistical analysis was performed by Student's t- or Chi-square test for continuous and categorical data, respectively.

RESULTS

No patient of Group A developed signs of thyrotoxicosis. SNR_L, CNR_L and diagnostic accuracy of CTE were 8.4 ± 1.7 vs 8.9 ± 2.1 (p = 0.256), 5.4 ± 1.5 vs 5.6 ± 1.7 (p = 0.486) and 91.1 vs 92.5% (p = 0.764) whereas the effective dose and the LOCM administered were 6.7 ± 2.2 vs 13.9 ± 6.0 mSv (p < 0.001) and 144 ± 25 vs 122 ± 25 ml (p < 0.001) for Group A and B, respectively.

CONCLUSION

LR-HC CTE is a dose-effective protocol in the evaluation of active IBD in young patients.

Differences in the imaging of Crohn's disease patients between North America and Europe: are we ready to bridge the divide?

The emphasis of treatment in Crohn's disease has evolved from a reactive model to "treat-to-target" approaches. Cross-sectional imaging has rapidly evolved in parallel, with a growing evidence base supporting its abilities for diagnosis, monitoring and prognostication. Whilst there are differences in emphasis between Europe and North America, particularly around the type of imaging modalities and patterns of multidisciplinary care, there is increasing convergence. This perspective piece provides an overview of the evolving role of cross-sectional imaging in Crohn's disease, discusses practice differences between North America and Europe and provides suggestions on areas for future collaboration and research priorities.

Advanced CT Techniques for Decreasing Radiation Dose, Reducing Sedation Requirements, and Optimizing Image Quality in Children

CT is an invaluable diagnostic tool for pediatric patients; however, concerns have arisen about the potential risks of ionizing radiation associated with diagnostic imaging in young patients, particularly for pediatric populations that may require serial CT examinations. Recent attention has also been focused on the immediate and long-term risks of administration of anesthetic medications to infants and young children who require sedation to undergo imaging examinations. These concerns can be mitigated with use of advanced CT techniques that can decrease scan time and radiation dose while preserving image quality. In this article, current state-of-the-art CT acquisition techniques are reviewed as part of a comprehensive strategy to reduce radiation dose, decrease sedation needs, and optimize image quality in infants and young children. Three imaging strategies are discussed, including (a) dual-energy CT (DECT), (b) imaging with a low tube potential, and (c) rapid scanning. Consolidating multiphase imaging protocols into a single phase with virtual nonenhanced imaging on DECT scanners, as well as use of low tube voltage, can reduce the radiation dose while increasing the conspicuity of contrast material-enhanced structures with a reduced volume of iodinated contrast material and a reduced rate of injection. Rapid scanning techniques with either ultrahigh pitch at dual-source CT or with wide-area detector single-source CT facilitate scanning without the need for sedation in many children. ^©RSNA, 2019 See discussion on this article by Szczykutowicz .

Patient centring and scan length: how inaccurate practice impacts on radiation dose in CT colonography (CTC)

OBJECTIVE

The aim of this study was to acknowledge errors in patients positioning in CT colonography (CTC) and their effect in radiation exposure.

MATERIALS AND METHODS

CTC studies of a total of 199 patients coming from two different referral hospitals were retrospectively reviewed. Two parameters have been considered for the analysis: patient position in relation to gantry isocentre and scan length related to the area of interest. CTDI vol and DLP were extracted for each patient. In order to evaluate the estimated effective total dose and the dose to various organs, we used the CT-EXPO^® software version 2.2. This software provides estimates of effective dose and doses to the other various organs.

RESULTS

Average value of the patients' position is found to be below the isocentre for 48 ± 25 mm and 29 ± 27 mm in the prone and supine position. It was observed that the increase in CTDI and DLP values for patients in Group 1, due to the inaccurate positioning, was estimated at about 30% and 20% for prone and supine position, respectively, while in Group 2, a decrease in CTDI and DLP values was estimated at about 16% and 18% for prone and supine position, respectively, due to an average position above isocentre. A dose increase ranging from 4 up to 13% was calculated with increasing the over-scanned region below anal orifice.

CONCLUSION

Radiographers and radiologists need to be aware of dose variation and noise effects on vertical positioning and over-scanning. More accurate training need to be achieved even so when examination protocol varies from general practice.

Computed Tomography Technology-and Dose-in the 21st Century

In the last decade or so, a number of disruptive technological advances have taken place in x-ray computed tomography, making possible new clinical applications. Changes in scanner design have included the use of two x-ray sources and two detectors or the use of large detector arrays that provide 16 cm of longitudinal coverage in one gantry rotation. These advances have allowed images of the entire heart to be acquired in just one heartbeat, lowering the effective dose from cardiac computed tomography from ~15 mSv to <1 mSv. Dual-energy computed tomography is now in widespread clinical use, enabling the assessment of material composition and concentration, as well as a range of new clinical applications. An emerging technology known as photon-counting detector computed tomography directly measures the energies of detected photons and is capable of simultaneously acquiring more than two energy data sets. Photon-counting detector computed tomography also provides advantages such as the ability to reject electronic noise, better iodine contrast-to-noise for a given dose, and spatial resolution as fine as 150 μm. Optimized x-ray tube potential selection has allowed reduction in radiation and contrast doses. Finally, wide adoption of iterative reconstruction and noise-reduction techniques has occurred. In all, body computed tomography doses have fallen dramatically, for example, by over a factor of 3 from the early 1980s. All of these advances increase the medical benefit and decrease the potential radiation risk associated with computed tomography. However, care must be taken to ensure that doses are not lowered to the level at which the clinical task is compromised.

Novel Imaging Approaches in Inflammatory Bowel Diseases

Inflammatory bowel diseases are chronic autoimmune conditions of the gastrointestinal tract, mainly grouped into ulcerative colitis or Crohn's disease. Traditionally, symptoms have been used to guide IBD management, but this approach is fatally flawed, as symptoms don't correlate with disease activity and often fail to predict disease complications, especially with Crohn's disease. Hence, there is increasing recognition of the need for treatment algorithms based on objective measures of bowel inflammation. In this review, we will focus on advancements in the endoscopic and radiological imaging armamentarium that allow detailed assessments from intestinal mucosa to mesentery.

Computed Tomography Enterography

Computed tomography (CT) enterography is a noninvasive imaging modality with superb spatial and temporal resolution, specifically tailored to evaluate the small bowel. It has several advantages over other radiologic and optical imaging modalities, all of which serve as complementary investigations to one another. This article describes CTE technique, including dose reduction techniques, special considerations for the pediatric population, common technical and interpretive pitfalls, and reviews some of the more common small bowel entities seen with CTE.

Creeping fat in patients with ileo-colonic Crohn's disease correlates with disease activity and severity of inflammation: A preliminary study using energy spectral computed tomography

OBJECTIVE

To investigate the relationship between creeping fat and inflammatory activity as well as the prognosis of ileo-colonic Crohn's disease (CD), based on a quantitative analysis of energy spectral computed tomography (CT).

METHODS

A total of 40 patients with CD and 40 with other gastrointestinal diseases who underwent an energy spectral CT scanning between March 2014 and March 2015 were retrospectively enrolled. The endoscopic severity of CD was evaluated by the simple endoscopic score for Crohn's disease (SES-CD). The slope of the Hounsfield unit (HU) curve (λ_HU ) was measured and calculated on energy spectral CT images. Visceral and subcutaneous fat areas were also measured. The relationship between the quantitative data of creeping fat as well as the fat area and CD inflammation were analyzed.

RESULTS

The λ_HU of creeping fat in patients with CD increased with the severity of intestinal inflammation (moderate/severe vs mild: -0.17 ± -0.68 vs -0.49 ± -0.61, P < 0.01). Moreover, the λ_HU of creeping fat around the intestinal segments without lesions in CD was significantly larger than that in the controls (-1.19 ± -0.56 vs - 1.42 ± -0.45, P < 0.01). The λ_HU was more accurate for detecting inflammatory lesions in CD than for calculating visceral fat. It was significantly correlated with SES-CD (r = 0.66, P < 0.01) and moderately correlated with the Harvey-Bradshaw index (r = 0.414, P < 0.01).

CONCLUSION

The quantitative analysis of creeping fat using energy spectral CT is an effective method in inflammatory evaluation in patients with CD.

New cross-sectional imaging in IBD

PURPOSE OF REVIEW

Cross-sectional imaging, namely ultrasound, CT and MR enterography, complements clinical and endoscopic monitoring of activity and complications in IBD, and emerging new radiological technologies may have clinical applications in the near future. This review offers an update on the potential role of these new imaging methods in the management of IBD.

RECENT FINDINGS

Specific MR techniques [diffusion-weighted imaging (DWI), diffusion kurtosis imaging (DKI) and magnetization transfer] allow accurate detection of inflammation (DWI and maybe DKI) and fibrosis (magnetization transfer) in Crohn's disease, without the need of intravenous gadolinium administration. ultrasonography developments (elastography, contrast-enhanced ultrasonography, small intestine contrast ultrasonography and multispectral optoacoustic tomography) are promising techniques for evaluation of fibrosis (elastography) and inflammation (contrast ultrasonography). Dose-reduction techniques in CT allow similar quality imaging and diagnostic accuracy with lower radiation exposure. Hybrid imaging (PET/MR and PET/CT) hold promise for grading inflammation in Crohn's disease.

SUMMARY

The potential benefits of new cross-sectional imaging techniques in IBD include better inflammation grading, such as identification of mild degree of activity, which may be relevant whenever assessing response to treatment and, of uttermost importance, accurate preoperative detection and grading of fibrosis in stricturing Crohn's disease, facilitating surgical vs. medical therapeutic decisions.

CT Angiography in the Lower Extremity Peripheral Artery Disease Feasibility of an Ultra-Low Volume Contrast Media Protocol

Purpose

The ALARA principle is not only relevant for effective dose (ED) reduction, but also applicable for contrast media (CM) management. Therefore, the aim was to evaluate the feasibility of an ultra-low CM protocol in the assessment of peripheral artery disease (PAD).

Materials and methods

Fifty PAD patients were scanned on third-generation dual-source computed tomography, from diaphragm to the forefoot, as follows: tube voltage: 70 kV, reference effective tube current: 90 mAs, collimation: 192 × 2 × 0.6 mm, with individualized acquisition timing. The protocol ED (mSv) was quantified with dedicated software. CM protocol consisted of 15 ml test bolus and 30 ml main bolus (300 mgI/ml) injected at 5 ml/s, followed by a 40 ml saline chaser at the same flow rate. Aorto-popliteal bolus transit time was used to calculate the overall acquisition time and delay. Objective (hounsfield units—HU; contrast-to-noise ratio—CNR) and subjective image quality (four-point Likert score) were assessed at different anatomical regions from the aorta down to the forefoot.

Results

Mean attenuation values were exceeding 250 HU from aorta down to the anterior tibial artery with CNR < 13. However, decline in attenuation was observed in more distal region with mean values of 165 and 199 HU, in left and right dorsalis pedis artery, respectively. Mode subjective image quality from the level of aorta down to the popliteal segment was excellent; below the knee mode score was good. The mean ED per protocol was 1.1 ± 0.5 mSv.

Conclusion

Use of an ultra-low CM volume protocol at 70 kV is feasible in the evaluation of PAD, resulting in good to excellent image quality with mean ED of 1.1 ± 0.5 mSv.

Level of evidence

Level 3, Local non-random sample

Kaleidoscopic View of Bowel Tuberculosis on Multi- Detector Computed Tomography (CT) Enterography - A Novel Technique Unfolding an Archaic Disease

Gastrointestinal tuberculosis (GI TB) is an important manifestation of abdominal tuberculosis (TB), an extra-pulmonary form of the disease. GI TB commonly affects the small bowel but is difficult to diagnose due to the challenge of evaluating the entire length of overlapping small bowel loops with traditional diagnostic methods like Barium meal follow through, abdominal computed tomography (CT), and endoscopy. New techniques of CT/MR enteroclysis/enterography are now available which specifically image the small bowel. MDCT enterography (MDCTE) is a non-invasive, simple to perform, modified abdominal CT imaging technique permitting reasonably accurate evaluation of the small bowel lumen, wall, perienteric tissues, and solid organs within the abdomen. As GI TB can cause morphological alterations in and around the small bowel, MDCTE seems to be an attractive modality for patients suspected of abdominal or GI TB. As scarce literature is available on MDCTE on tuberculosis, we present a pictorial review on MDCTE findings in patients with GI tuberculosis proved on FNAC and clinical and/or imaging follow-up.

The combination of a reduction in contrast agent dose with low tube voltage and an adaptive statistical iterative reconstruction algorithm in CT enterography: Effects on image quality and radiation dose

To investigate the subjective and quantitative image quality and radiation exposure of CT enterography (CTE) examination performed at low tube voltage and low concentration of contrast agent with adaptive statistical iterative reconstruction (ASIR) algorithm, compared with conventional CTE.One hundred thirty-seven patients with suspected or proved gastrointestinal diseases underwent contrast enhanced CTE in a multidetector computed tomography (MDCT) scanner. All cases were assigned to 2 groups. Group A (n = 79) underwent CT with low tube voltage based on patient body mass index (BMI) (BMI < 23 kg/m, 80 kVp; BMI ≥ 23 kg/m, 100 kVp) and low concentration of contrast agent (270 mg I/mL), the images were reconstructed with standard filtered back projection (FBP) algorithm and 50% ASIR algorithm. Group B (n = 58) underwent conventional CTE with 120 kVp and 350 mg I/mL contrast agent, the images were reconstructed with FBP algorithm. The computed tomography dose index volume (CTDIvol), dose length product (DLP), effective dose (ED), and total iodine dosage were calculated and compared. The CT values, contrast-to-noise ratio (CNR), and signal-to-noise ratio (SNR) of the normal bowel wall, gastrointestinal lesions, and mesenteric vessels were assessed and compared. The subjective image quality was assessed independently and blindly by 2 radiologists using a 5-point Likert scale.The differences of values for CTDIvol (8.64 ± 2.72 vs 11.55 ± 3.95, P < .001), ED (6.34 ± 2.24 vs 8.52 ± 3.02, P < .001), and DLP (422.6 ± 149.40 vs 568.30 ± 213.90, P < .001) were significant between group A and group B, with a reduction of 25.2%, 25.7%, and 25.7% in group A, respectively. The total iodine dosage in group A was reduced by 26.1%. The subjective image quality did not differ between the 2 groups (P > .05) and all image quality scores were greater than or equal to 3 (moderate). Fifty percent ASIR-A group images provided lower image noise, but similar or higher quantitative image quality in comparison with FBP-B group images.Compared with the conventional protocol, CTE performed at low tube voltage, low concentration of contrast agent with 50% ASIR algorithm produce a diagnostically acceptable image quality with a mean ED of 6.34 mSv and a total iodine dose reduction of 26.1%.

Prospective Comparison of Standard- Versus Low-Radiation-Dose CT Enterography for the Quantitative Assessment of Crohn Disease

OBJECTIVE

CT enterography (CTE) is sensitive and specific for active inflammatory changes of Crohn disease (CD), but its use has been limited by exposure to ionizing radiation. The objective of this study is to show the noninferiority of a model-based iterative reconstruction (MBIR) technique using lower radiation doses compared with standard-dose CTE in the assessment of CD.

SUBJECTS AND METHODS

Patients referred to a hospital radiology department for CTE for the evaluation of CD underwent both a standard examination (used to generate filtered back-projection and adaptive statistical iterative reconstruction [ASIR] images) and low-dose MBIR CTE performed in a random sequence on the same day. Images were reviewed by two radiologists for signs of small-bowel CD. Radiologic findings obtained using ASIR and clinical assessments of disease activity served as the reference standard for comparison with low-dose CTE findings.

RESULTS

A total of 163 patients, 92 (56.4%) of whom had active disease, underwent CTE. MBIR was found to be noninferior to the two standard-dose techniques, with no significant differences noted between the three types of images when compared with the clinical reference standard. As compared with the radiologic standard of ASIR, the very-low-dose scans had a high degree of accuracy, with sensitivity ranging from 0.85 to 0.94 and specificity ranging from 0.84 to 0.97 depending on the reader. A significant reduction in radiation exposure was noted with MBIR (mean [± SD] reduction, 3.30 ± 3.17 mSv) versus standard-dose imaging (7.16 ± 4.61 mSv; p < 0.001).

CONCLUSION

Low-dose CTE using MBIR is sensitive and specific for the detection of active inflammatory changes of CD while utilizing radiation doses substantially lower than those associated with standard techniques.

Imaging in Patients with Crohn's Disease: Trends in Abdominal CT/MRI Utilization and Radiation Exposure Considerations over a 10-Year Period

PURPOSE

To study the trends in utilization of computed tomography (CT) and magnetic resonance imaging (MRI) in patients with Crohn's disease and to evaluate changes in CT radiation exposure over a 10-year period.

METHODS

In this institutional review board-approved single-institution retrospective study, we included patients who underwent CT and MRIs for evaluation of Crohn's disease between 2006 and 2015. A total of 3196 CTs and 1924 MR scans were performed in 2156 patients (mean age: 34.8 ± 17.71 yr; range: 3-91 yr) for initial diagnosis or follow-up of Crohn's disease between 2006 and 2015. Trends in CT/MR utilization was assessed by comparing the volume of CT/MRI studies performed each year. The changes in CT radiation exposure over the study period were estimated and compared.

RESULTS

The annual combined CT/MR utilization demonstrated a 1.9-fold rise over the last decade (2006: n = 358, 2015: n = 681, P < 0.001, r = 0.96). It was predominantly because of a substantial growth (9.2-fold increase) in the MR scan volume (2006: n = 37, 2015: n = 341, P < 0.001, r = 0.93), whereas CT volume did not show significant change (2006: n = 321, 2015: n = 340, P = 0.6). Over this same period, there was a 59.4% reduction in mean radiation exposure (2006: CT dose indexvol 16.9 ± 7.1 mGy, 2015: CT dose indexvol 6.87 ± 4.62 mGy, P < 0.001).

CONCLUSIONS

A 9-fold growth in annual MR scan volume contributed to a nearly 2-fold rise in yearly cross-sectional imaging utilization in Crohn's patients between 2006 and 2015. Rising trend in imaging utilization paralleled a 60% reduction of CT radiation exposure.

Intestinal tuberculosis versus crohn's disease: Clinical and radiological recommendations

Intestinal tuberculosis is a common clinical problem in India. The clinical features of this disease are nonspecific and can be very similar to Crohn's disease. Radiological evaluation of the small bowel has undergone a paradigm shift in the last decade. This long tubular organ that has traditionally been difficult to evaluate can now be well-visualized by some innovative imaging and endoscopic techniques. This article highlights the state-of-the-art evaluation of ulceroconstrictive diseases of the bowel and provides recommendations for the differentiation of intestinal tuberculosis from Crohn's disease.

Risk factors for radiation exposure in newly diagnosed IBD patients

PURPOSE

Patients with inflammatory bowel disease (IBD) may be exposed to high doses of diagnostic radiation. The purpose of this study is to identify subsets of this population at risk for significant radiation exposure.

METHODS

This HIPAA compliant, IRB approved study consists of 336 patients (237 adult and 99 pediatric) within the Ocean State Crohn's & Colitis Area Registry (OSCCAR). All were newly diagnosed with IBD and prospectively enrolled between 1/2008 and 12/2012. Comprehensive chart review was performed.

RESULTS

207 (61.6%) patients were diagnosed with Crohn's disease (CD), 120 (35.7%) with ulcerative colitis (UC), and 9 (2.7%) with inflammatory bowel disease, type unspecified (IBDU). 192 (57.1%) patients were exposed to GI-specific radiation. Average GI-specific radiation dose for adult IBD patients was 14.1 mSV and was significantly greater among adult CD than adult UC patients (p = 0.01). Pediatric patients underwent fewer CT scans (p < 0.0001). Risk factors for increased radiation exposure include: GI surgery (p = 0.003), biologic therapy (p = 0.01), pain-predominant symptoms (as compared to diarrhea-predominant symptoms; p < 0.05), and isolated ileal disease (p = 0.02). Patients with stricturing or penetrating disease received higher radiation doses than patients with non-stricturing, non-penetrating disease (p < 0.0001).

CONCLUSIONS

A variety of risk factors are associated with increased exposure to ionizing radiation after diagnosis of IBD. Knowledge of these risk factors can help physicians prospectively identify patients at risk for elevated radiation exposure and consider low-dose or radiation-free imaging.

Observer performance for adaptive, image-based denoising and filtered back projection compared to scanner-based iterative reconstruction for lower dose CT enterography

PURPOSE

The purpose of this study was to compare observer performance for detection of intestinal inflammation for low-dose CT enterography (LD-CTE) using scanner-based iterative reconstruction (IR) vs. vendor-independent, adaptive image-based noise reduction (ANLM) or filtered back projection (FBP).

METHODS

Sixty-two LD-CTE exams were performed. LD-CTE images were reconstructed using IR, ANLM, and FBP. Three readers, blinded to image type, marked intestinal inflammation directly on patient images using a specialized workstation over three sessions, interpreting one image type/patient/session. Reference standard was created by a gastroenterologist and radiologist, who reviewed all available data including dismissal Gastroenterology records, and who marked all inflamed bowel segments on the same workstation. Reader and reference localizations were then compared. Non-inferiority was tested using Jackknife free-response ROC (JAFROC) figures of merit (FOM) for ANLM and FBP compared to IR. Patient-level analyses for the presence or absence of inflammation were also conducted.

RESULTS

There were 46 inflamed bowel segments in 24/62 patients (CTDIvol interquartile range 6.9-10.1 mGy). JAFROC FOM for ANLM and FBP were 0.84 (95% CI 0.75-0.92) and 0.84 (95% CI 0.75-0.92), and were statistically non-inferior to IR (FOM 0.84; 95% CI 0.76-0.93). Patient-level pooled confidence intervals for sensitivity widely overlapped, as did specificities. Image quality was rated as better with IR and AMLM compared to FBP (p < 0.0001), with no difference in reading times (p = 0.89).

CONCLUSIONS

Vendor-independent adaptive image-based noise reduction and FBP provided observer performance that was non-inferior to scanner-based IR methods. Adaptive image-based noise reduction maintained or improved upon image quality ratings compared to FBP when performing CTE at lower dose levels.

CT enterography: technical and interpretive pitfalls

CT enterography is a first-line test at many institutions to investigate potential small bowel disorders. While numerous articles have focused on the ability of CT enterography to diagnose and stage Crohn's disease, small bowel neoplasia, and malabsorptive or vascular disorders, this article reviews CT enterography limitations, technical and interpretive pitfalls, image review tactics, and complementary radiologic and endoscopic examinations to improve diagnostic accuracy. CT enterography limitations include its inability to demonstrate isolated mucosal abnormalities such as aphthous ulcers and its use of ionizing radiation. The most common technical pitfall of CT enterography is inadequate small bowel distention resulting from inadequate ingestion, gastric retention, or rapid small bowel transit of a large volume of neutral enteric contrast material. Additionally, segments of jejunum are frequently collapsed. Interpretive pitfalls commonly result from peristaltic contractions, transient intussusception and opaque intraluminal debris. Opaque debris is especially problematic during multiphasic CT enterography performed to identify potential small bowel sources of obscure gastrointestinal bleeding. False-negative examinations may result from inadequate radiation dose. Examinations complementary to CT enterography include small bowel follow through, enteroclysis, CT enteroclysis, MR enterography, MR enteroclysis, capsule endoscopy, and balloon-assisted endoscopy. Properly performed and accurately interpreted CT enterography contributes to the diagnosis and management of small bowel disease by itself and as a complement to other radiologic and optical small bowel imaging examinations.

Pediatric inflammatory bowel disease: imaging issues with targeted solutions

To date, there have been many advances in inflammatory bowel disease (IBD) imaging in every cross-sectional imaging modality, particularly in children. The main emphasis in pediatric IBD imaging is on robust and reproducible measures of small bowel Crohn's disease inflammation, accurate diagnosis of IBD-related complications, and minimizing radiation burden to the patient, as repeat imaging is necessary over the course of their disease. In this article, we discuss the current state-of-the-art imaging techniques, in addition to routine fluoroscopy, including MR and CT enterography and bowel ultrasound. We also present the emerging use of new methods to characterize disease severity and distinguish active inflammation from fibrosis such as diffusion-weighted imaging, bowel elastography, and contrast-enhanced ultrasound. The diagnostic performance of particular examinations, their strengths and weaknesses, and role in IBD management will be discussed. Although these advanced imaging techniques applied to children are similar to those performed in adults, special considerations related to their application in pediatric patients will also be reviewed.

Role of imaging in the evaluation of inflammatory bowel disease: How much is too much?

Inflammatory bowel disease (IBD) is a lifelong condition with waxing and waning disease course that requires reassessment of disease status as well as screening for complications throughout a patient’s lifetime. Laboratory testing, endoscopic assessment, and fecal biomarkers are often used in the initial diagnosis and ongoing monitoring of a patient with IBD. Imaging plays an integral role in the diagnosis and evaluation of IBD. Different imaging modalities can be used over the course of a patient’s lifetime, from the initial screening and diagnosis of IBD, to determining the extent of intestinal involvement, monitoring for disease activity, and evaluating for complications of uncontrolled IBD. The various imaging modalities available to the provider each have a unique set of risks and benefits when considering cost, radiation exposure, need for anesthesia, and image quality. In this article we review the imaging techniques available for the evaluation of IBD including fluoroscopic small bowel follow-through, computed tomography enterography, magnetic resonance enterography, and transabdominal ultrasound with particular focus on the judicious use of imaging and the risks and benefits of each option. We also review the risks of ionizing radiation, strategies to reduce exposure to ionizing radiation, and current imaging guidelines among pediatric and adult patient with IBD.

Methods for clinical evaluation of noise reduction techniques in abdominopelvic CT

Most noise reduction methods involve nonlinear processes, and objective evaluation of image quality can be challenging, since image noise cannot be fully characterized on the sole basis of the noise level at computed tomography (CT). Noise spatial correlation (or noise texture) is closely related to the detection and characterization of low-contrast objects and may be quantified by analyzing the noise power spectrum. High-contrast spatial resolution can be measured using the modulation transfer function and section sensitivity profile and is generally unaffected by noise reduction. Detectability of low-contrast lesions can be evaluated subjectively at varying dose levels using phantoms containing low-contrast objects. Clinical applications with inherent high-contrast abnormalities (eg, CT for renal calculi, CT enterography) permit larger dose reductions with denoising techniques. In low-contrast tasks such as detection of metastases in solid organs, dose reduction is substantially more limited by loss of lesion conspicuity due to loss of low-contrast spatial resolution and coarsening of noise texture. Existing noise reduction strategies for dose reduction have a substantial impact on lowering the radiation dose at CT. To preserve the diagnostic benefit of CT examination, thoughtful utilization of these strategies must be based on the inherent lesion-to-background contrast and the anatomy of interest. The authors provide an overview of existing noise reduction strategies for low-dose abdominopelvic CT, including analytic reconstruction, image and projection space denoising, and iterative reconstruction; review qualitative and quantitative tools for evaluating these strategies; and discuss the strengths and limitations of individual noise reduction methods.

CT of the Abdomen with Reduced Tube Voltage in Adults: A Practical Approach

Recent innovations in computed tomographic (CT) hardware and software have allowed implementation of low tube voltage imaging into everyday CT scanning protocols in adults. CT at a low tube voltage setting has many benefits, including (a) radiation dose reduction, which is crucial in young patients and those with chronic medical conditions undergoing serial CT examinations for disease management; and (b) higher contrast enhancement. For the latter, increased attenuation of iodinated contrast material improves the evaluation of hypervascular lesions, vascular structures, intestinal mucosa in patients with bowel disease, and CT urographic images. Additionally, the higher contrast enhancement may provide diagnostic images in patients with renal dysfunction receiving a reduced contrast material load and in patients with suboptimal peripheral intravenous access who require a lower contrast material injection rate. One limitation is that noisier images affect image quality at a low tube voltage setting. The development of denoising algorithms such as iterative reconstruction has made it possible to perform CT at a low tube voltage setting without compromising diagnostic confidence. Other potential pitfalls of low tube voltage CT include (a) photon starvation artifact in larger patients, (b) accentuation of streak artifacts, and (c) alteration of the CT attenuation value, which may affect evaluation of lesions on the basis of conventional enhancement thresholds. CT of the abdomen with a low tube voltage setting is an excellent radiation reduction technique when properly applied to imaging of select patients in the appropriate clinical setting.

Risk factors of radiation dose in patients undergoing peripherally-inserted central catheter procedure using conventional angiography equipment and flat panel detector-based mobile C-arm fluoroscopy

BACKGROUND

Although peripherally-inserted central catheter (PICC) insertion is commonly performed under fluoroscopic guidance, few reports have addressed performance and dosimetry when PICC is inserted under C-arm fluoroscopy.

PURPOSE

To evaluate the risk factors of radiation dose in performing PICC insertion using flat panel detector-based mobile C-arm fluoroscopy and a conventional angiography machine.

MATERIAL AND METHODS

Ninety-eight patients underwent the PICC procedure using conventional angiography equipment (n=49) or flat panel detector-based mobile C-arm fluoroscopy (n=49). Data were prospectively analyzed from July to November 2012. Dose-area product (DAP), tube voltage, tube current, fluoroscopy time, and image quality measured on a 5-point scale were estimated and compared using appropriate statistical tests.

RESULTS

There were no significant differences in tube voltage, fluoroscopy time, and image quality between conventional angiography and mobile C-arm fluoroscopy. DAP, mean arm tube current, and tube current in chest fluoroscopy were significantly lower in mobile C-arm fluoroscopy than using the conventional angiography machine (P < 0.05). Multivariate analysis identified tube current in chest fluoroscopy, arm tube current, and fluoroscopy equipment as significant risk factors for elevated radiation dose in PICC insertion.

CONCLUSION

PICC insertion can be performed using flat panel detector-based mobile C-arm fluoroscopy instead of a conventional angiography machine. Image quality and fluoroscopy time were not different between the two systems and the use of C-arm fluoroscopy significantly reduced radiation dose.

Imaging modalities in pediatric inflammatory bowel disease

PURPOSE OF REVIEW

To review the various imaging modalities in the evaluation of pediatric inflammatory bowel disease (IBD) to determine disease location, clinical phenotype and the severity of disease in order to optimize treatment.

RECENT FINDINGS

Assessment of the extent, location and severity of IBD routinely involves imaging of the gastrointestinal tract. Cross-sectional modalities such as magnetic resonance enterography (MRE) and computed tomography enterography visualize the lumen, transmural involvement, extraintestinal manifestations and may facilitate decision-making in disease management. MRE has evolved as the imaging modality of choice for many pediatric IBD indications because it does not involve exposure to ionizing radiation.

SUMMARY

Advances in imaging modalities have revolutionized the assessment of children with IBD in recent years. Small-bowel follow-through is no longer considered the imaging modality of choice in this setting. Cross-sectional enterography is now preferred because, among other advantages, it can potentially distinguish active inflammation from fibrosis, characterize stricturing and penetrating complications, and diagnose extraintestinal manifestations. Although MRE avoids ionizing radiation exposure, it remains costly. Cross-sectional imaging and endoscopy complement each other in the development of objective measures for the assessment of disease activity and monitoring of response to treatment.

Vertebral body Hounsfield units as a predictor of incidental durotomy in primary lumbar spinal surgery

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To assess the association between vertebral body Hounsfield unit (HU) measurements on quantitative computed tomography and the risk for incidental durotomy (ID).

SUMMARY OF BACKGROUND DATA

ID during spine surgery has been associated with adverse postoperative sequelae that may require prolonged hospital stay and reoperation. Previously identified independent risk factors include age, revision surgery, and lumbar surgery.

METHODS

ID was prospectively documented in spine surgery patients at a single institution during a 2-year period (incidence: 4%, 191/4,822). Patients with ID were matched 1:1 to a control cohort without ID based on age and sex. Inclusion criteria for both cohorts were primary lumbar surgery and quantitative computed tomographic scans within 1 year of date of surgery. Demographic, radiographical, and intraoperative data, along with dual x-ray absorptiometry t scores, were collected and analyzed.

RESULTS

A total of 71 patients with ID met the inclusion criteria (38 male, 33 female). Average age of patients with ID was 63.8 ± 12.9 years (range: 34-85 yr). Computed tomographic scans were acquired 1.5 ± 2.2 months away from date of surgery (range: 0-12 mo). Inter-rater reliability for HU measurements between a fellowship-trained spine surgeon and a research fellow was strong (r = 0.901, P < 0.001). HU values were significantly lower in patients with ID than controls (149.2 ± 60.7 [range: 44.5-301.5] versus 177.0 ± 81.4, [range: 62.0-524.0], respectively; P = 0.023). The area under the receiver operating characteristic curve was 0.603 (P = 0.034). A threshold of 169 HU optimized sensitivity (0.718) and specificity (0.451), and patients with HU value 169 or less were found to be at increased risk for ID (odds ratio: 2.092, 95% confidence interval: 1.042-4.201, P = 0.037).

CONCLUSION

Lower HU value is an accessible clinical marker for increased risk of ID. A threshold value of HU was defined (≤169) that may be used clinically to identify patients at elevated risk for ID, which may improve the informed decision making process prior to spinal surgery.

LEVEL OF EVIDENCE

3.