Distortionless, free-breathing, and respiratory resolved 3D diffusion weighted imaging of the abdomen.

PURPOSE: Abdominal imaging is frequently performed with breath holds or respiratory triggering to reduce the effects of respiratory motion. Diffusion weighted sequences provide a useful clinical contrast but have prolonged scan times due to low signal-to-noise ratio (SNR), and cannot be completed in a single breath hold. Echo-planar imaging (EPI) is the most commonly used trajectory for diffusion weighted imaging but it is susceptible to off-resonance artifacts. A respiratory resolved, three-dimensional (3D) diffusion prepared sequence that obtains distortionless diffusion weighted images during free-breathing is presented. Techniques to address the myriad of challenges including: 3D shot-to-shot phase correction, respiratory binning, diffusion encoding during free-breathing, and robustness to off-resonance are described. METHODS: A twice-refocused, M1-nulled diffusion preparation was combined with an RF-spoiled gradient echo readout and respiratory resolved reconstruction to obtain free-breathing diffusion weighted images in the abdomen. Cartesian sampling permits a sampling density that enables 3D shot-to-shot phase navigation and reduction of transient fat artifacts. Theoretical properties of a region-based shot rejection are described. The region-based shot rejection method was evaluated with free-breathing (normal and exaggerated breathing), and respiratory triggering. The proposed sequence was compared in vivo with multishot DW-EPI. RESULTS: The proposed sequence exhibits no evident distortion in vivo when compared to multishot DW-EPI, robustness to B0 and B1 field inhomogeneities, and robustness to motion from different respiratory patterns. CONCLUSION: Acquisition of distortionless, diffusion weighted images is feasible during free-breathing with a b-value of 500 s/mm2, scan time of 6 min, and a clinically viable reconstruction time.

Hyperpolarized 13 C metabolic imaging of the human abdomen with spatiotemporal denoising.

PURPOSE: Improving the quality and maintaining the fidelity of large coverage abdominal hyperpolarized (HP) 13 C MRI studies with a patch based global-local higher-order singular value decomposition (GL-HOVSD) spatiotemporal denoising approach. METHODS: Denoising performance was first evaluated using the simulated [1-13 C]pyruvate dynamics at different noise levels to determine optimal kglobal and klocal parameters. The GL-HOSVD spatiotemporal denoising method with the optimized parameters was then applied to two HP [1-13 C]pyruvate EPI abdominal human cohorts (n = 7 healthy volunteers and n = 8 pancreatic cancer patients). RESULTS: The parameterization of kglobal = 0.2 and klocal = 0.9 denoises abdominal HP data while retaining image fidelity when evaluated by RMSE. The kPX (conversion rate of pyruvate-to-metabolite, X = lactate or alanine) difference was shown to be <20% with respect to ground-truth metabolic conversion rates when there is adequate SNR (SNRAUC > 5) for downstream metabolites. In both human cohorts, there was a greater than nine-fold gain in peak [1-13 C]pyruvate, [1-13 C]lactate, and [1-13 C]alanine apparent SNRAUC . The improvement in metabolite SNR enabled a more robust quantification of kPL and kPA . After denoising, we observed a 2.1 ± 0.4 and 4.8 ± 2.5-fold increase in the number of voxels reliably fit across abdominal FOVs for kPL and kPA quantification maps. CONCLUSION: Spatiotemporal denoising greatly improves visualization of low SNR metabolites particularly [1-13 C]alanine and quantification of [1-13 C]pyruvate metabolism in large FOV HP 13 C MRI studies of the human abdomen.

The impact of variations in subject geometry, respiration and coil repositioning on the specific absorption rate in parallel transmit abdominal imaging at 7 T.

Parallel transmit MRI at 7 T has increasingly been adopted in research projects and provides increased signal-to-noise ratios and novel contrasts. However, the interactions of fields in the body need to be carefully considered to ensure safe scanning. Recent advances in physically flexible body coils have allowed for high-field abdominal imaging, but the effects of increased variability on energy deposition need further exploration. The aim of this study was to assess the impact of subject geometry, respiration phase and coil positioning on the specific absorption rate (SAR). Ten healthy subjects (body mass index [BMI] = 25 ± 5 kg m-2 ) were scanned (at 3 T) during exhale breath-hold and images used to generate body models. Seven of these subjects were also scanned during inhale. Simplifications of the coil and body models were first explored, and then finite-difference time-domain simulations were run with a typical eight-channel parallel transmit coil positioned over the abdomen. Simulations were used to generate 10 g averaged SAR (SAR10g ) maps across 100,000 phase settings, and the worst-case scenario 10 g averaged SAR (wocSAR10g ) was identified using trigonometric maximisation. The average maximum SAR10g across the 10 subjects with 1 W input power per channel was 1.77 W kg-1 . Hotspots were always close to the body surface near the muscle wall boundary. The wocSAR10g across the 10 subjects ranged from 2.3 to 3.2 W kg-1 and was inversely correlated to fat volume percentage (R = 8) and BMI (R = 0.6). The coefficient of variation values in SAR10g due to variations in subject geometry, respiration phase and realistic coil repositioning were 12%, 4% and 12%, respectively. This study found that the variability due to realistic coil repositioning was similar to the variability due to differing healthy subject geometries for abdominal imaging. This is important as it suggests that population-based modelling is likely to be more useful than individual modelling in setting safe thresholds for abdominal imaging.

Influence of spectral shaping and tube voltage modulation in ultralow-dose computed tomography of the abdomen.

PURPOSE: Unenhanced abdominal CT constitutes the diagnostic standard of care in suspected urolithiasis. Aiming to identify potential for radiation dose reduction in this frequent imaging task, this experimental study compares the effect of spectral shaping and tube voltage modulation on image quality. METHODS: Using a third-generation dual-source CT, eight cadaveric specimens were scanned with varying tube voltage settings with and without tin filter application (Sn 150, Sn 100, 120, 100, and 80 kVp) at three dose levels (3 mGy: standard; 1 mGy: low; 0.5 mGy: ultralow). Image quality was assessed quantitatively by calculation of signal-to-noise ratios (SNR) for various tissues (spleen, kidney, trabecular bone, fat) and subjectively by three independent radiologists based on a seven-point rating scale (7 = excellent; 1 = very poor). RESULTS: Irrespective of dose level, Sn 100 kVp resulted in the highest SNR of all tube voltage settings. In direct comparison to Sn 150 kVp, superior SNR was ascertained for spleen (p ≤ 0.004) and kidney tissue (p ≤ 0.009). In ultralow-dose scans, subjective image quality of Sn 100 kVp (median score 3; interquartile range 3-3) was higher compared with conventional imaging at 120 kVp (2; 2-2), 100 kVp (1; 1-2), and 80 kVp (1; 1-1) (all p < 0.001). Indicated by an intraclass correlation coefficient of 0.945 (95% confidence interval: 0.927-0.960), interrater reliability was excellent. CONCLUSIONS: In abdominal CT with maximised dose reduction, tin prefiltration at 100 kVp allows for superior image quality over Sn 150 kVp and conventional imaging without spectral shaping.

Prevalence of intra-abdominal injury among patients with seatbelt signs, a systematic review and meta-analysis.

INTRODUCTION: The advancement of seat belts have been essential to reducing morbidity and mortality related to motor vehicle collisions (MVCs). The "seat belt sign" (SBS) is an important physical exam finding that has guided management for decades. This study, comprising a systematic review and random-effects meta-analysis, asses the current literature for the likelihood of the SBS relating to intra-abdominal injury and surgical intervention. METHODS: PubMed and Scopus databases were searched from their beginnings through August 4, 2023 for eligible studies. Outcomes included the prevalence of intra-abdominal injury and need for surgical intervention. Cochrane's Risk of Bias (RoB) tool and the Newcastle-Ottawa Scale (NOS) were applied to assess risk of bias and study quality; Q-statistics and I2 values were used to assess for heterogeneity. RESULTS: The search yielded nine observational studies involving 3050 patients, 1937 (63.5%) of which had a positive SBS. The pooled prevalence of any intra-abdominal injury was 0.42, (95% CI 0.28-0.58, I2 = 96%) The presence of a SBS was significantly associated with increased odds of intra-abdominal injury (OR 3.62, 95% CI 1.12-11.6, P = 0.03; I2 = 89%), and an increased likelihood of surgical intervention (OR 7.34, 95% CI 2.03-26.54, P < 0.001; I2 = 29%). The measurement for any intra-abdominal injury was associated with high heterogeneity, I2 = 89%. CONCLUSION: This meta-analysis suggests that the presence of a SBS was associated with a statistically significant higher likelihood of intra-abdominal injury and need for surgical intervention. The study had high heterogeneity, likely due to the technological advancements over the course of this study, including seat belt design and diagnostic imaging sensitivity. Further studies with more recent data are needed to confirm these results.

Spontaneous splenic rupture in a neonate: a case report and literature review.

Splenic rupture in a neonate is a rare but potentially fatal condition that may trigger evaluation for child abuse. It is a diagnosis of exclusion that has been reported in the surgical literature but may be underrecognized by pediatric radiologists. We report a case of a newborn with an unremarkable prenatal, delivery, and nursery course who presented with anemia, abdominal distension, and lethargy. Abdominal ultrasound with Doppler and computed tomography (CT) of the head, cervical spine, chest, abdomen, and pelvis without contrast showed findings of splenic rupture and anoxic brain injury. An extensive workup for traumatic, infectious, coagulopathic, and congenital etiologies was unrevealing, leading to a presumptive diagnosis of spontaneous splenic rupture in a neonate.

Pearls and Pitfalls of Imaging Small Bowel Obstruction.

Small bowel obstruction (SBO) is a common condition encountered by radiologists in the evaluation of patients with abdominal pain, and is an important diagnosis to be comfortable with given substantial associated morbidity and mortality. In this review, we summarize an imaging approach to evaluating patients with suspected SBO, discuss the role of certain imaging modalities such as radiography and small bowel follow through, CT, and MRI, as well as review some common and also less common causes of SBO such as internal hernia. We will also discuss tailoring the imaging approach to address specific clinical questions and special patient populations such as imaging the pregnant patient with suspected SBO, and the inflammatory bowel disease patient.

Imaging of Right Lower Quadrant Pain in Children and Adolescents: AJR Expert Panel Narrative Review.

Right lower quadrant (RLQ) pain is a common clinical presentation in children, and accurate clinical diagnosis remains challenging given that this nonspecific presentation is associated with numerous surgical and nonsurgical conditions. The broad differential diagnosis varies by patient age and sex. Important considerations in the selection of a diagnostic imaging strategy include the sequencing, performance, and cost of tests. This article provides a comprehensive narrative review of the diagnostic imaging of RLQ pain in children and adolescents, including a discussion of the complementary roles of ultrasound, CT, and MRI; description of key imaging findings based on available evidence; and presentation of salient differential diagnoses. Subspecialized pediatric emergency medicine and surgical perspectives are also provided as further clinical insight into this common, but often challenging, scenario. Finally, the current status of imaging of RLQ pain in children and adolescents is summarized on the basis of expert consensus.

Cancellation of streak artifacts in radial abdominal imaging using interference null space projection.

PURPOSE: In radial abdominal imaging, it has been commonly observed that signal from the arms cause streaks due to system imperfections. We previously introduced a streak removal technique (B-STAR), which is inherently spatially variant and limited to work in image space. In this work, we propose a spatially invariant streak cancellation technique (CACTUS), which can be applied in either image space or k-space and is compatible with iterative reconstructions. THEORY AND METHODS: Streak sources are typically spatially localized and can be represented using a low-dimensional subspace. CACTUS identifies the streak subspace by leveraging the spatial redundancy of receiver coils and projects the data onto the streak null space to eliminate the streaks. When applied in k-space, CACTUS can be combined with iterative reconstructions. CACTUS was tested in phantoms and in vivo abdominal imaging using a radial turbo spin-echo pulse sequence. RESULTS: In phantoms, CACTUS improved T2 estimation in comparison to previous de-streaking methods. In vivo experiments showed that CACTUS reduced streaks and yielded T2 estimation, in regions affected by streaks, closer to a streak-free reference. Evaluation using a clinical abdominal dataset (n = 20) showed that CACTUS is comparable to B-STAR and yields significantly better signal preservation and streak cancellation than coil removal and suppression methods. CONCLUSION: CACTUS provides superior signal preservation and streak reduction performance compared to coil removal and suppression methods. As a clear advantage over B-STAR, CACTUS can be integrated with iterative reconstruction methods. In abdominal T2 mapping, CACTUS improves the accuracy of parameter estimation in areas affected by streaks.

Improving B1+ homogeneity in abdominal imaging at 3 T with light, flexible, and compact metasurface.

PURPOSE: Radiofrequency field inhomogeneity is a significant issue in imaging large fields of view in high- and ultrahigh-field MRI. Passive shimming with coupled coils or dielectric pads is the most common approach at 3 T. We introduce and test light and compact metasurface, providing the same homogeneity improvement in clinical abdominal imaging at 3 T as a conventional dielectric pad. METHODS: The metasurface comprising a periodic structure of copper strips and parallel-plate capacitive elements printed on a flexible polyimide substrate supports propagation of slow electromagnetic waves similar to a high-permittivity slab. We compare the metasurface operating inside a transmit body birdcage coil to the state-of-the-art pad by numerical simulations and in vivo study on healthy volunteers. RESULTS: Numerical simulations with different body models show that the local minimum of B1+ causing a dark void in the abdominal domain is removed by the metasurface with comparable resulting homogeneity as for the pad with decreasing maximum and whole-body SAR values. In vivo results confirm similar homogeneity improvement and demonstrate the stability to body mass index. CONCLUSION: The light, flexible, and inexpensive metasurface can replace a relatively heavy and expensive pad based on the aqueous suspension of barium titanate in abdominal imaging at 3 T.

Abdominal T2-Weighted Imaging and T2 Mapping Using a Variable Flip Angle Radial Turbo Spin-Echo Technique.

BACKGROUND: T2 mapping is of great interest in abdominal imaging but current methods are limited by low resolution, slice coverage, motion sensitivity, or lengthy acquisitions. PURPOSE: Develop a radial turbo spin-echo technique with refocusing variable flip angles (RADTSE-VFA) for high spatiotemporal T2 mapping and efficient slice coverage within a breath-hold and compare to the constant flip angle counterpart (RADTSE-CFA). STUDY TYPE: Prospective technical efficacy. SUBJECTS: Testing performed on agarose phantoms and 12 patients. Focal liver lesion classification tested on malignant (N = 24) and benign (N = 11) lesions. FIELD STRENGTH/SEQUENCE: 1.5 T/RADTSE-VFA, RADTSE-CFA. ASSESSMENT: A constrained objective function was used to optimize the refocusing flip angles. Phantom and/or in vivo data were used to assess relative contrast, T2 estimation, specific absorption rate (SAR), and focal liver lesion classification. STATISTICAL TESTS: t-Tests or Mann-Whitney Rank Sum tests were used. RESULTS: Phantom data did not show significant differences in mean relative contrast (P = 0.10) and T2 accuracy (P = 0.99) between RADTSE-VFA and RADTSE-CFA. Adding noise caused T2 overestimation predominantly for RADTSE-CFA and low T2 values. In vivo results did not show significant differences in mean spleen-to-liver (P = 0.62) and kidney-to-liver (P = 0.49) relative contrast between RADTSE-VFA and RADTSE-CFA. Mean T2 values were not significantly different between the two techniques for spleen (T2VFA  = 109.2 ± 12.3 msec; T2CFA  = 110.7 ± 11.1 msec; P = 0.78) and kidney-medulla (T2VFA  = 113.0 ± 8.7 msec; T2CFA  = 114.0 ± 8.6 msec; P = 0.79). Liver T2 was significantly higher for RADTSE-CFA (T2VFA  = 52.6 ± 6.6 msec; T2CFA  = 60.4 ± 8.0 msec) consistent with T2 overestimation in the phantom study. Focal liver lesion classification had comparable T2 distributions for RADTSE-VFA and RADTSE-CFA for malignancies (P = 1.0) and benign lesions (P = 0.39). RADTSE-VFA had significantly lower SAR than RADTSE-CFA increasing slice coverage by 1.5. DATA CONCLUSION: RADTSE-VFA provided noise-robust T2 estimation compared to the constant flip angle counterpart while generating T2-weighted images with comparable contrast. The VFA scheme minimized SAR improving slice efficiency for breath-hold imaging. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY STAGE: 1.

Natural Language Processing for Imaging Protocol Assignment: Machine Learning for Multiclass Classification of Abdominal CT Protocols Using Indication Text Data.

A correct protocol assignment is critical to high-quality imaging examinations, and its automation can be amenable to natural language processing (NLP). Assigning protocols for abdominal imaging CT scans is particularly challenging given the multiple organ specific indications and parameters. We compared conventional machine learning, deep learning, and automated machine learning builder workflows for this multiclass text classification task. A total of 94,501 CT studies performed over 4 years and their assigned protocols were obtained. Text data associated with each study including the ordering provider generated free text study indication and ICD codes were used for NLP analysis and protocol class prediction. The data was classified into one of 11 abdominal CT protocol classes before and after augmentations used to account for imbalances in the class sample sizes. Four machine learning (ML) algorithms, one deep learning algorithm, and an automated machine learning (AutoML) builder were used for the multilabel classification task: Random Forest (RF), Tree Ensemble (TE), Gradient Boosted Tree (GBT), multi-layer perceptron (MLP), Universal Language Model Fine-tuning (ULMFiT), and Google's AutoML builder (Alphabet, Inc., Mountain View, CA), respectively. On the unbalanced dataset, the manually coded algorithms all performed similarly with F1 scores of 0.811 for RF, 0.813 for TE, 0.813 for GBT, 0.828 for MLP, and 0.847 for ULMFiT. The AutoML builder performed better with a F1 score of 0.854. On the balanced dataset, the tree ensemble machine learning algorithm performed the best with an F1 score of 0.803 and a Cohen's kappa of 0.612. AutoML methods took a longer time for completion of NLP model training and evaluation, 4 h and 45 min compared to an average of 51 min for manual methods. Machine learning and natural language processing can be used for the complex multiclass classification task of abdominal imaging CT scan protocol assignment.

Abdominal and pelvic imaging in the diagnosis of acute abdominal attacks in patients with hereditary angioedema due to C1-inhibitor deficiency.

Introduction: Hereditary angioedema (HAE) is a rare inherited autosomal dominant disease caused by deficiency or dysfunction of C1 inhibitor (C1INH). Clinical symptoms include recurrent subcutaneous and submucosal angioedema of the internal organs. Abdominal attacks affect more than 90% of patients, are often misdiagnosed and result in unnecessary surgical procedures. Aim: To analyse the utility of imaging studies (USG, CT) in patients with C1INH-HAE during an abdominal attack and remission. Material and methods: We enrolled 40 patients with type I and II HAE (30 women, 10 men; mean age 39 years). The diagnosis of C1INH-HAE was based on patient and family history, significantly reduced values of C1INH serum level and activity. Abdominal and pelvic ultrasound were performed in patients within the first 6 h of the abdominal attack and repeated during remission. Moreover, 23 cases underwent abdominal or pelvic computed tomography during acute abdominal symptoms. The most common ultrasound and CT findings showed the transient presence of a significant amount of fluid in the free abdominal cavity and intestinal oedema during the symptom progression and spontaneously disappearing during the seizure in 90% and 50% of patients, respectively. CT revealed also an enlargement of the mesenteric lymph nodes as well as a fat stranding along the bowel wall thickening. Conclusions: Ultrasound or CT imaging facilitates the diagnosis of the patient suspected of having an abdominal attack due to C1INH-HAE. They allow to identify transitional presence of an abundant fluid in the free abdominal cavity and intestinal swelling which spontaneously disappear with a symptoms attack.

Free-breathing abdominal T1 mapping using an optimized MR fingerprinting sequence.

In this work, we propose a free-breathing magnetic resonance fingerprinting (MRF) method that can be used to obtain B1+ -robust quantitative T1 maps of the abdomen in a clinically acceptable time. A three-dimensional MRF sequence with a radial stack-of-stars trajectory was implemented, and its k-space acquisition ordering was adjusted to improve motion-robustness in the context of MRF. The flip angle pattern was optimized using the Cramér-Rao Lower Bound, and the encoding efficiency of sequences with 300, 600, 900 and 1800 flip angles was evaluated. To validate the sequence, a movable multicompartment phantom was developed. Reference multiparametric maps were acquired under stationary conditions using a previously validated MRF method. Periodic motion of the phantom was used to investigate the motion-robustness of the proposed sequence. The best performing sequence length (600 flip angles) was used to image the abdomen during a free-breathing volunteer scan. When using a series of 600 or more flip angles, the estimated T1 values in the stationary phantom showed good agreement with the reference scan. Phantom experiments revealed that motion-related artifacts can appear in the quantitative maps and confirmed that a motion-robust k-space ordering is essential. The in vivo scan demonstrated that the proposed sequence can produce clean parameter maps while the subject breathes freely. Using this sequence, it is possible to generate B1+ -robust quantitative maps of T1 and B1+ next to M0 -weighted images under free-breathing conditions at a clinically usable resolution within 5 min.

Dynamic T2 mapping by multi-spin-echo spatiotemporal encoding.

PURPOSE: To develop a pulse sequence for acquiring robust, quantitative T2 relaxation maps in real time. METHODS: The pulse scheme relies on fully refocused spatiotemporally encoded multi-spin-echo trains, which provide images that are significantly less distorted than spin-echo echo planar imaging-based counterparts. This enables single-shot T2 mapping in inhomogeneity-prone regions. Another advantage of these schemes stems from their ability to interleave multiple scans in a reference-free manner, providing an option to increase sensitivity and spatial resolution with minimal motional artifacts. RESULTS: The method was implemented in preclinical and clinical scanners, where single-shot acquisitions delivered reliable T2 maps in ≤200 ms with ≈250 µm and ≈3 mm resolutions, respectively. Ca. 4 times higher spatial resolutions were achieved for the motion-compensated interleaved versions of these acquisitions, delivering T2 maps in ca. 10 s per slice. These maps were nearly indistinguishable from multi-scan relaxometric maps requiring orders-of-magnitude longer acquisitions; this was confirmed by mice head and real-time mice abdomen 7T scans performed following contrast-agent injections, as well as by 3T human brain and breast scans. CONCLUSION: This study introduced and demonstrated a new approach for acquiring rapid and quantitative T2 data, which is particularly reliable when operating at high fields and/or targeting heterogeneous organs or regions.

Utilization Trends in Abdominal Imaging, 2004-2016.

OBJECTIVE. The purpose of this study was to analyze recent trends in abdominal imaging utilization in the Medicare population. MATERIALS AND METHODS. Medicare Part B databases for 2004-2016 were reviewed, and all Current Procedural Terminology codes pertaining to noninvasive imaging of the abdomen and pelvis were identified. Codes were grouped into six categories: CT and CT angiography (CTA), MRI and MR angiography (MRA), ultrasound, radionuclide imaging, radiography, and gastrointestinal fluoroscopy. Annual utilization rates per 1000 Medicare beneficiaries were calculated. Medicare physician specialty codes were used to identify studies performed by radiologists versus nonradiologist physicians. Reimbursements were determined. RESULTS. Total abdominal imaging utilization decreased from 558.0 examinations per 1000 Medicare beneficiaries in 2004 to 441.9 in 2016 (-20.8%). CT and CTA examinations increased by 22.5% from 2004 to 2010, followed by a sharp drop in 2011 caused by code bundling. From 2011 to 2016, CT and CTA use increased by only 7.2%. Radiography utilization decreased from 129.6 examinations per 1000 Medicare beneficiaries in 2004 to 91.5 in 2016 (-29.4%). Radionuclide studies decreased from 14.0 to 9.5 (-32.1%), and gastrointestinal fluoroscopy decreased from 37.8 examinations to 22.5 (-40.5%). Utilization of ultrasound increased slightly (1.5%), whereas MRI and MRA utilization sharply increased on a percentage basis (81.2%). Reimbursements peaked in 2009 at $1.704 billion, dropped substantially in 2011 because of code bundling, and remained relatively stable thereafter. The radiologists' market share of abdominal imaging was approximately 87% in both 2004 and 2016. CONCLUSION. Abdominal imaging utilization rates have declined in recent years, in part due to code bundling, but also largely because of a decrease in the use of abdominal radiography, gastrointestinal fluoroscopy, and nuclear imaging. Reimbursements have also declined. This study also showed that most of the abdominal imaging was performed by radiologists.

Exploring the neglected segment of the intestine: the duodenum and its pathologies.

Herein we reviewed the computed tomography (CT) findings of a spectrum of pathological entities affecting the duodenum. We discuss the CT findings of some congenital, inflammatory, traumatic, and neoplastic pathologies of the duodenum along with the conventional barium studies of selected conditions. Pathologies of this C-shaped intestinal segment, derived from both foregut and midgut, are often overlooked in clinical practice and radiological literature. While congenital anomalies like duplication cysts and diverticula are usually asymptomatic, annular pancreas and malrotation may manifest in the first decade of life. Primary as well as secondary involvement of the duodenum by various disease processes can be evaluated by careful CT technique and proper attention to the duodenum. Among congenital conditions, annular pancreas, duplication cyst, superior mesenteric artery syndrome, midgut volvulus, and diverticula are presented. Duodenal involvement in adenocarcinoma, lymphoma, gastrointestinal stromal tumours, Crohn's disease, and groove pancreatitis are discussed. Duodenal wall haematoma and traumatic duodenal perforation causing pneumoretroperitoneum in two patients after blunt trauma of the abdomen are also illustrated. CT provides superb anatomic detail and offers high diagnostic specificity for the detection of duodenal pathologies because it allows direct imaging of the intestinal wall, secondary signs of bowel disease within the surrounding mesentery, and abnormal findings in adjacent structures. Primary duodenal malignancies and local extension from adjacent malignancies can be diagnosed by CT reliably. CT also plays a vital role in the diagnosis of traumatic duodenal injury by differentiating between mural haematoma and a duodenal perforation because the latter requires immediate surgical intervention.

Fat misbehaving in the abdominal cavity: a pictorial essay.

Intra-abdominal fat is abundantly present in both the peritoneum and retroperitoneum. Fat necrosis or inflammation are common findings in abdominal imaging. The most common pathologies that we encounter are epiploic appendagitis, omental infarction, mesenteric panniculitis, and encapsulated fat necrosis. Less common entities that can occur are pancreatic saponification, heterotopic mesenteric ossification, and pseudolipoma of the capsule of Glisson. These entities can mimic more urgent pathologies such as appendicitis, diverticulitis, or malignancies.

Radial streak artifact reduction using phased array beamforming.

PURPOSE: A new method for streak artifact reduction in radial MRI based on phased array filtering. THEORY: Radial imaging in applications that require large fields-of-view can be susceptible to streaking artifacts due to gradient nonlinearities. Coil removal methods prune the coils contributing the most to streaking artifacts at the expense of signal loss. Phased array beamforming is a form of spatial filtering used to suppress unwanted signals. The proposed method uses interference covariance generated from the streaking artifact samples which are manually extracted with phased array beamforming to suppress streaking in the images. METHODS: The performance of the proposed method was evaluated on abdomen radial fast spin echo images acquired on a 1.5T Siemens scanner and compared with previously proposed methods. RESULTS: Our results demonstrate that the proposed method can effectively suppress streaking artifacts without any noticeable loss in signal levels. Coil removal methods can suppress streaks as well but they may incur significant signal loss due to coil pruning. Quantitative metrics also demonstrate the superiority of the proposed method over earlier methods. CONCLUSION: The use of interference covariance with phased array beamforming can help reduce streaking artifacts.

How We Do It: Creating Consistent Structure and Content in Abdominal Radiology Report Templates.

OBJECTIVE: The purposes of this article are to describe the creation of template report formats and content for a variety of abdominal and pelvic CT and MRI examinations and discuss a review-of-systems approach to text and avoidance of pitfalls of report templates. CONCLUSION: Organ system-specific report templates for CT and MRI incorporate radiologist preferences. Disease-specific report templates are created from these reports to provide a consistent radiologist and referring physician experience across the report templates.