The Target Sign: Bowel Wall

Imaging the post-treatment pelvis with gynecologic cancers

Gynecological malignancies, such as ovarian cancers, cervical cancers, and endometrial cancers, have a significant global impact. Women with gynecologic malignancies may receive a single or a combination of treatments, including surgery, chemotherapy, and radiation-based therapies. Radiologists utilize various diagnostic imaging modalities to provide the surgeon with relevant information about the diagnosis, prognosis, optimal surgical strategy, and prospective post-treatment imaging. Computerized Tomography (CT) and magnetic resonance imaging (MRI) may be used initially to evaluate and detect post-treatment complications. Although CT is primarily used for staging, MRI is commonly used for a more accurate evaluation of a tumor's size and detection of local invasion. Complications such as hematoma, abscess, inclusion cyst, seroma, tumor thrombosis, anorectovaginal fistula, and gossypiboma may occur after the three primary treatments, and systems such as the genitourinary, gastrointestinal, neurological, and musculoskeletal may be affected. In order to distinguish between early-onset and late-onset complications following gynecological treatment, radiological findings of the most common post-treatment complications will be presented in this review.

Small Bowel Imaging from Stepchild of Roentgenology to MR Enterography: Part I: Guidance in Performing and Observing Normal and Abnormal Imaging Findings

MRE has become a standard imaging test for evaluating patients with small bowel pathology, but the indications, interpretation of imaging findings, methodology, and appropriate use must be standardized and widely known. Several signs of small bowel damage in inflammatory and non-inflammatory small bowel pathology include strictures, abscess, inflammatory activity, sinus tract, wall edema, fistula, mucosal lesions, and mesentery fat hypertrophy, all of which are widely and accurately explained by MRE. MRE is a non-invasive modality that accurately assesses the intra-luminal, parietal, and extra-luminal small bowel. The differential MRE appearance allows us to distinguish between different small bowel pathologies, such as neoplastic and non-neoplastic small bowel diseases. The purpose of this paper is to present the MRE technique, as well as the interpretation of imaging findings, through the approach of a rigorous stepwise methodology.

Computed tomography enterography-based multiregional radiomics model for differential diagnosis of Crohn's disease from intestinal tuberculosis

PURPOSE

To build computed tomography enterography (CTE)-based multiregional radiomics model for distinguishing Crohn's disease (CD) from intestinal tuberculosis (ITB).

MATERIALS AND METHODS

A total of 105 patients with CD and ITB who underwent CTE were retrospectively enrolled. Volume of interest segmentation were performed on CTE and radiomic features were obtained separately from the intestinal wall of lesion, the largest lymph node (LN), and region surrounding the lesion in the ileocecal region. The most valuable radiomic features was selected by the selection operator and least absolute shrinkage. We established nomogram combining clinical factors, endoscopy results, CTE features, and radiomic score through multivariate logistic regression analysis. Receiver operating characteristic (ROC) curves and decision curve analysis (DCA) were used to evaluate the prediction performance. DeLong test was applied to compare the performance of the models.

RESULTS

The clinical-radiomic combined model comprised of four variables including one radiomic signature from intestinal wall, one radiomic signature from LN, involved bowel segments on CTE, and longitudinal ulcer on endoscopy. The combined model showed good diagnostic performance with an area under the ROC curve (AUC) of 0.975 (95% CI 0.953-0.998) in the training cohort and 0.958 (95% CI 0.925-0.991) in the validation cohort. The combined model showed higher AUC than that of the clinical model in cross-validation set (0.958 vs. 0.878, P = 0.004). The DCA showed the highest benefit for the combined model.

CONCLUSION

Clinical-radiomic combined model constructed by combining CTE-based radiomics from the intestinal wall of lesion and LN, endoscopy results, and CTE features can accurately distinguish CD from ITB.

Manifestations of Sickle Cell Disorder at Abdominal and Pelvic Imaging

Sickle cell disorder (SCD) refers to a spectrum of hematologic disorders that cause a characteristic clinical syndrome affecting the entire body. It is the most prevalent monogenetic hemoglobinopathy worldwide, with a wide range of focal and systemic expressions. Hemoglobin gene mutation leads to the formation of abnormal sickle-shaped red blood cells, which cause vascular occlusion and result in tissue and organ ischemia and infarction. Recurrent episodes of acute illness lead to progressive multisystem organ damage and dysfunction. Vaso-occlusion, hemolysis, and infection as a result of functional asplenia are at the core of the disease manifestations. Imaging plays an essential role in the diagnosis and management of SCD-related complications in the abdomen and pelvis. A thorough understanding of the key imaging findings of SCD complications involving hepatobiliary, gastrointestinal, genitourinary, and musculoskeletal systems is crucial to timely recognition and accurate diagnosis. The authors aim to familiarize the radiologist with the SCD spectrum, focusing on the detection and evaluation of manifestations that may appear at imaging of the abdomen and pelvis. The topics the authors address include (a) the pathophysiology of the disease, (b) the placement of SCD among hemoglobinopathies, (c) the clinical presentation of SCD, (d) the role of imaging in the evaluation and diagnosis of patients with SCD who present with abdominal and pelvic manifestations in addition to extraperitoneal manifestations detectable at abdominal or pelvic imaging, (e) imaging features associated with common and uncommon sequelae of SCD in abdominal and pelvic imaging studies, and (f) a brief overview of management and treatment of patients with SCD. Online supplemental material is available for this article. ^©RSNA, 2022.

Small bowel obstruction and intestinal ischemia: emphasizing the role of MDCT in the management decision process

The objective of this article is to assess the computed tomography (CT) findings of small bowel obstruction (SBO) complicated by ischemia. SBO is a frequent clinical entity characterized by high morbidity and mortality. The radiologic aim is not just to diagnose the obstruction itself but to rule out the presence of complications related to SBO. This is crucial for differentiating which patients can be safely treated non-operatively from the ones who may need an urgent surgical approach. The main complication of SBO is intestinal ischemia. In the emergency setting, CT imaging is the modality of choice for SBO because of its ability to assess the bowel wall, the supporting mesentery and peritoneal cavity all in one. On the other hand, the radiologist who documents an intestinal ischemia should think about SBO as possible cause. In this case, the main finding which helps the radiologist in the identification of SBO is the presence of multiple and packed valvulae conniventes in the dilated bowel wall and the "transition zone" that indicates the passage between compressed and decompressed small bowel, otherwise the localization of the obstruction cause. Once the site of obstruction has been recognized, the other issue is to assess the cause of obstruction, considering that the most common cause of SBO remains "unidentified" and related to intra-abdominal adhesions. After that, the following most important point is to rule out the presence of an ischemic bowel and mesenteric changes associated to SBO. CT signs of bowel ischemia include reduced or increased bowel wall enhancement, mesenteric edema or engorgement, fluid or free air in the peritoneal cavity. This condition usually leads to an urgent laparotomy and, in some cases, to a surgical resection.

Imaging side effects and complications of chemotherapy and radiation therapy: a pictorial review from head to toe

Newer biologic drugs and immunomodulatory agents, as well as more tolerated and effective radiation therapy schemes, have reduced treatment toxicity in oncology patients. However, although imaging assessment of tumor response is adapting to atypical responses like tumor flare, expected changes and complications of chemo/radiotherapy are still routinely encountered in post-treatment imaging examinations. Radiologists must be aware of old and newer therapeutic options and related side effects or complications to avoid a misinterpretation of imaging findings. Further, advancements in oncology research have increased life expectancy of patients as well as the frequency of long-term therapy-related side effects that once could not be observed. This pictorial will help radiologists tasked to detect therapy-related complications and to differentiate expected changes of normal tissues from tumor relapse.

Clinical Features of Ischemic Enteritis Diagnosed by Double-Balloon Endoscopy

INTRODUCTION

Ischemic enteritis (IE) is a relatively rare small bowel disease that is diagnosed via double-balloon endoscopy (DBE), although the lack of established diagnostic criteria can make it difficult to confirm the diagnosis. This study aimed to describe the clinical characteristics, endoscopic imaging features, and treatments for IE at our center. Patients and Methods. We retrospectively searched the DBE database (1,521 patients) at Nagoya University Hospital for patients with IE and collected data regarding endoscopic findings, clinical background, and histological findings. The cases were categorized according to whether they involved transient or stenotic IE.

RESULTS

The DBE database included 24 patients (14 men) with IE. Transient IE was identified in 9 patients, and stenotic IE was identified in 15. Half of the patients had a history of cerebrovascular and cardiovascular disease. A granular structure at the ulcer base was the most frequently observed DBE finding at the stenotic site. Enterography using the contrast medium revealed that transient IE had a similar stenotic lesion length, relative to stenotic IE, although stenotic IE had a significantly higher stenosis ratio (81% vs. 63%, P=0.033). Small bowel enteroclysis revealed the "lead pipe" sign (11 patients), thumbprinting (3 patients), and the serrated lumen sign (1 patient). Only 1 patient with stenotic IE experienced recurrence after conservative treatment.

CONCLUSION

During DBE, IE was characterized by cannular stenosis with extended and variable ulceration types, which spread over the edge of the stenosis, and a granular appearance at the ulcer base. These findings may help guide the diagnosis of IE.

Chest CT target sign in a couple with COVID-19 pneumonia

We describe a target sign on chest CT characterized by a combination of peripheral ring-like opacity and a central nodular ground-glass opacity surrounding a vessel in a couple with COVID-19 pneumonia confirmed by real-time reverse transcriptase fluorescence polymerase chain reaction sputum analysis.

Contrast-Enhanced CT for the Diagnosis of Acute Mesenteric Ischemia

OBJECTIVE. The purpose of this article is to provide an overview of the diagnostic and prognostic roles of CT in the management of acute mesenteric ischemia. CONCLUSION. Acute mesenteric ischemia is defined as inadequate blood supply to the gastrointestinal tract resulting in ischemic and inflammatory injury. The prognosis is poor without treatment. Contrast-enhanced CT has become the cornerstone of diagnosis to identify features of vascular disorders and of intestinal ischemic injury and to visualize bowel necrosis.

Targets and Combs: A Case of Lupus Enteritis

Lupus is a common autoimmune disorder with the potential to affect all organ systems. Lupus enteritis is a rare complication that is seen in a subset of patients that present with gastrointestinal symptoms. Its diagnosis commonly involves imaging, showing bowel wall edema as the target sign and vascular engorgement of bowel vessels as the comb sign on CT scans. These findings can help guide the diagnosis, but they are nonspecific and are also found in other conditions that cause bowel wall ischemia. These symptoms are reversible if treated with immunosuppressants. Unfortunately, recurrence is common in lupus enteritis and perforation needs to be ruled out on presentation. In this report, we present the case of a patient with known lupus who was diagnosed with lupus enteritis on imaging and was treated with immunosuppressants. The patient's symptoms resolved subsequently. Our case highlights the fact that the appropriate diagnosis and management of this condition require physical exams, labs, and imaging.

CT-Visualized Colonic Mural Stratification Independently Predicts the Need for Medical or Surgical Rescue Therapy in Hospitalized Ulcerative Colitis Patients

BACKGROUND

Severe ulcerative colitis is associated with significant morbidity. Multidetector computed tomography (MDCT) scans are frequently obtained upon hospital admission, but the ability of radiographic findings to predict steroid failure is unknown.

AIM

To identify MDCT features predictive of inpatient rescue in hospitalized UC.

METHODS

Patients hospitalized with UC who underwent a CT scan within 48 h of hospitalization were retrospectively identified. Radiologists blinded to the outcome prospectively evaluated CT scans for the presence of bowel wall thickening, stranding, and hyperenhancement as well as mural stratification, mesenteric hyperemia, and proximal dilation. Logistic regression adjusting for potential confounders was used to test the independent association between radiographic findings and need for rescue therapy.

RESULTS

The study cohort included 74 patients. The mean age of the group was 45 years, and two-thirds (66%) were male. Twenty-eight (38%) patients required either inpatient medical rescue or colectomy. The mean number of positive radiographic findings was 4.4 (range 2-6) with a higher median number of findings in those who required rescue therapy (5 vs. 4, p = 0.03). Mural stratification was significantly more common among those who required rescue therapy (92% vs. 49%, p = 0.001). No other radiographic findings were independently associated with inpatient rescue. On multivariable analysis, mural stratification (OR 14.9, 95% CI 2.76-80.2) and number of positive findings (OR 2.10, 95% CI 1.06-4.16) remained independently predictive of the need for rescue therapy.

CONCLUSIONS

Mural stratification was highly predictive of steroid refractoriness and need for medical or surgical rescue therapy in hospitalized UC.

[Imaging of gastrointestinal inflammation : Characteristic patterns and signs]

CLINICAL PROBLEM

Pathological conditions of the gastrointestinal tract can result from various disorders, including inflammatory, infectious, neoplastic, and ischemic diseases.

RADIOLOGICAL STANDARD PROCEDURES

Cross-sectional imaging techniques have largely replaced many of the conventional fluoroscopic examinations, such as small bowel follow-through and double-contrast barium enema. The former allow for time-efficient, accurate, and minimally invasive diagnostics. Therefore, they have become important diagnostic tools for the evaluation of inflammatory diseases of the gastrointestinal tract. The distension of the intestinal lumen with orally administered neutral contrast media improves not only the evaluation of the intraluminal aspect, but also of the cross-sectional appearance. Furthermore, with cross-sectional imaging techniques, the additional assessment of the extraintestinal structures and organs is also possible.

METHODICAL INNOVATIONS AND ASSESSMENT

With the ongoing development of scanner and software technology, pathologic conditions of the gastrointestinal wall can be characterized in more detail by both computed tomography and magnetic resonance imaging. A structured approach, based on the analysis of typical radiological signs and patterns, combined with the evaluation of extraintestinal findings may help to assign the observed imaging findings to specific disease groups.

RECOMMENDATIONS

This article summarizes common signs and typical patterns frequently seen in inflammatory conditions of the gastrointestinal tract. A systematic approach for structured analysis of specific and nonspecific imaging features and common pitfalls may aid in the interpretation and help to narrow the spectrum of potential differential diagnoses.

Gastrointestinal tract involvement in acute pancreatitis: initial findings and follow-up by magnetic resonance imaging

Background

To study the initial and follow up patterns of gastrointestinal tract involvement in acute pancreatitis (AP) using magnetic resonance imaging (MRI).

Methods

A total of 209 patients with AP undergoing abdominal MRI on 1.5 T MRI were compared to 100 control patients selected from our daily clinical caseload who underwent MRI over the same recruitment period and had no other disease which can cause abnormality of gastrointestinal tract. Initial and follow up MRI examinations of gastrointestinal tract abnormalities were noted for AP patients. The severity of AP was graded by the MRSI and APACHE II. Spearman correlation of gastrointestinal tract involvement with MRSI and APACHE II was analyzed.

Results

In 209 patients with AP, 63% of the AP patients on their initial MRI exams and 5% of control subjects had at least one gastrointestinal tract abnormality (P<0.05). In the control group, thirty-seven patients were normal on MRI, 24 patients with renal cysts, eighteen patients with liver cysts, eleven patients with liver hemangiomas, and ten patients with splenomegaly. The abnormalities of gastrointestinal tract observed in AP patients included thickened stomach wall (20%), thickened duodenum wall (27%), thickened ascending colon wall (11%), thickened transverse colon wall (15%), and thickened descending colon wall (26%), among others. Gastrointestinal tract abnormalities were correlated with the MRSI score (r=0.46, P<0.05) and APACHE II score (r=0.19, P<0.05). Among 62 patients who had follow up examinations, 26% of patients had gastrointestinal tract abnormality, which was significantly lower than that in the initial exams (P<0.05). Resolution of gastrointestinal tract abnormal MRI findings coincided with symptom alleviation in AP patients.

Conclusions

Gastrointestinal tract abnormalities on MRI are common in AP and they are positively correlated with the severity of AP. It may add value for determining the severity of AP.

Predictive factors of gastroduodenal bleeding after postoperative radiotherapy in biliary tract cancer

Objective

To identify predictive factors for gastroduodenal bleeding after postoperative radiation therapy in patients with biliary tract cancer.

Methods

We identified 186 patients with biliary tract cancer who completed scheduled postoperative radiation therapy from March 2000 to August 2013. To isolate the effects of radiation on gastroduodenal bleeding, patients with pylorus-preserving pancreaticoduodenectomy, pylorus-resecting pancreaticoduodenectomy or Whipple surgery (n = 67) were excluded from this analysis. Postoperative radiation therapy was started at a median 5 weeks (range: 4-12 weeks) after surgery with a median dose of 44 Gy (range: 44-54), and chemotherapy was also concurrently administered to 102 patients.

Results

The median age of the patients was 59 years (range: 36-76 years). Of the 119 patients, 26 had intrahepatic cholangiocarcinoma, 29 had hilar cholangiocarcinoma, while 64 had extrahepatic tumors (gallbladder cancer, n = 53; proximal bile duct cancer, n = 10; choledochal cyst cancer, n = 1). Of all, 11 patients (9%) developed gastroduodenal bleeding. In univariate analyses, hepatic artery resection and gastroduodenal wall thickening on postoperative radiation therapy simulation computed tomography were statistically significant factors for gastroduodenal bleeding. Multivariate analysis by a logistic regression model using those two variables revealed that both parameters were independent predictors for gastroduodenal bleeding.

Conclusions

Concomitant hepatic artery resection and presence of gastroduodenal wall thickening on postoperative radiation therapy simulation computed tomography were predictive factors for gastroduodenal bleeding after postoperative radiation therapy in biliary tract cancer. In such cases, patients should be informed of the high risk of gastroduodenal bleeding, and should be closely observed during and after postoperative radiation therapy.

Cytomegalovirus Colitis: An Uncommon Mimicker of Common Colitides

Cytomegalovirus latency, though ubiquitous in the human population, is known to cause colitis in both immunocompromised and immunocompetent hosts. Furthermore, the clinical, endoscopic, and histologic appearance of cytomegalovirus colitis can mimic that of inflammatory bowel disease, an extremely well-documented disease. In this context, though many reports have looked at inflammatory bowel disease with superimposed cytomegalovirus infection, less attention has been paid to cytomegalovirus as a primary cause of isolated colitis. Owing to the rarity of this phenomenon, it is important to consider this diagnosis and implement proper testing to avoid misdiagnosis and mismanagement.

CT abdominal imaging findings in patients with sickle cell disease: acute vaso-occlusive crisis, complications, and chronic sequelae

Sickle cell disease (SCD) is the most prevalent hemoglobinopathy. Survival in patients with SCD has improved over the past few decades. These patients experience a lifetime of repeated acute pain crises, which are thought to result from sickling and microvascular occlusions; acute abdominal pain is common. Moreover, repeated crises often lead to organ dysfunction, such as asplenia, hepatic failure, and renal failure. The spleen, liver, biliary system, kidneys, and gastrointestinal tract can all be affected. Patients may undergo CT to further direct clinical management. We review the spectrum of CT imaging findings of abdominal manifestations in patients with SCD, from the acute microvascular occlusive pain crisis to the potential complications and chronic sequelae.

Gastrointestinal manifestations of systemic disease: a multimodality review

Systemic diseases have many different presentations, including imaging findings in the bowel. Recognizing the imaging findings in these diseases is important in making the correct diagnosis. Although certain imaging features overlap, knowledge of specific findings along with the clinical presentation aid in narrowing the differential or in making an imaging diagnosis. The pictorial review will focus on the gastrointestinal manifestations of systemic diseases, including amyloidosis, angiotensin converter enzyme inhibitor-induced angioedema, celiac sprue, distal intestinal obstruction syndrome, graft-versus-host disease, hemolytic uremic syndrome, hemophilia, Henoch-Schönlein purpura, intestinal lymphangiectasia, mastocytosis, scleroderma, systemic lupus erythematosus, Wegener's granulomatosis, and Whipple's disease. The aforementioned diseases can be subdivided based upon the underlying process leading to the disease. The diseases discussed are categorized into autoimmune, infiltrative, treatment related, congenital/hereditary, and infectious etiologies.

CT of Gastrointestinal Vasoocclusive Crisis Complicating Sickle Cell Disease

OBJECTIVE

The purposes of this article are to illustrate the CT appearance of gastrointestinal vasoocclusive crisis in patients with sickle cell disease (SCD), highlight potential complications, and review other conditions that may have similar findings.

CONCLUSION

The gastrointestinal vasoocclusive crisis in SCD is rare but can result in potentially life-threatening ischemia and death. Knowledge of the spectrum of CT features of the gastrointestinal vasoocclusive crisis is important in making the diagnosis and potentially preventing complications.

Computed tomography features associated with operative management for nonstrangulating small bowel obstruction

BACKGROUND

The management of nonstrangulating small bowel obstruction (SBO) may require surgery, but the need for and timing of surgical intervention isn't always apparent. We sought to determine whether specific features on computed tomography (CT) can predict the necessity for operative management.

METHODS

Two radiologists independently reviewed CT scans from all patients admitted to hospital with SBO between 2004 and 2006. We examined the association between radiographic features and operative management by univariate analysis using the χ(2) or Fisher exact test. Significant factors with high concordance between radiologists were entered into a multivariable stepwise logistic regression model.

RESULTS

There were 228 patients with SBO, 63 of whom met our inclusion criteria and had CT scans available for review. Three CT features were frequently associated with operative management and had good concordance between radiologists: complete bowel obstruction, small bowel dilation greater than 4 cm and transition point. Transition point was the only significant factor predictive of operative management for SBO on multivariable logistic regression analysis (OR 19, 95% confidence interval 1.8-201, p = 0.014).

CONCLUSION

In patients with nonstrangulating SBO, the presence of a transition point on CT scan should alert the surgeon to the increased likelihood that operative management may be required.

Bowel wall thickening at CT: simplifying the diagnosis

Objective

In this article we present a simplified algorithm-based approach to the thickening of the small and large bowel wall detected on routine computed tomography (CT) of the abdomen.

Background

Thickening of the small or large bowel wall may be caused by neoplastic, inflammatory, infectious, or ischaemic conditions. First, distinction should be made between focal and segmental or diffuse wall thickening. In cases of focal thickening further analysis of the wall symmetry and perienteric anomalies allows distinguishing between neoplasms and inflammatory conditions. In cases of segmental or diffuse thickening, the pattern of attenuation in light of clinical findings helps narrowing the differential diagnosis.

Conclusion

Focal bowel wall thickening may be caused by tumours or inflammatory conditions. Bowel tumours may appear as either regular and symmetric or irregular or asymmetric thickening. When fat stranding is disproportionately more severe than the degree of wall thickening, inflammatory conditions are more likely. With the exception of lymphoma, segmental or diffuse wall thickening is usually caused by benign conditions, such as ischaemic, infectious and inflammatory diseases.

Key points

• Thickening of the bowel wall may be focal (<5 cm) and segmental or diffuse (6-40 cm or >40 cm) in extension.

• Focal, irregular and asymmetrical thickening of the bowel wall suggests a malignancy.

• Perienteric fat stranding disproportionally more severe than the degree of wall thickening suggests an inflammatory condition.

• Regular, symmetric and homogeneous wall thickening is more frequently due to benign conditions, but can also be caused by neoplasms such as well-differentiated adenocarcinoma and lymphoma.

• Segmental or diffuse bowel wall thickening is usually caused by ischaemic, inflammatory or infectious conditions and the attenuation pattern is helpful in narrowing the differential diagnosis.

Magnetic resonance colonography in rats with TNBS-induced colitis: a feasibility and validation study

BACKGROUND

Magnetic resonance colonography (MRC) has been recently developed to assess bowel inflammation in inflammatory bowel disease (IBD) patients. Evaluating animal models of inflammation with MRC may be important in new drug-screening processes. The aim of this study was to assess the feasibility of MRC in colitic rats and confront it with model characteristics.

METHODS

Colitis was induced by rectal injection of trinitrobenzene-sulfonic acid (TNBS) in 13 rats while six rats received the vehicle. MRC was performed at day 2. Colon inflammation and production of inflammatory mediators were evaluated. Image quality was assessed by wall and motion artifacts. MRC criteria were bowel wall thickness, wall signal intensity on T2-weighted (T2w) and T1w images, the appearance of a target sign pattern, and irregular patterns of mucosal surface.

RESULTS

MRC quality was good or excellent in 16/21 examinations with no difference between groups. Colitis rats were significantly different from controls in terms of wall thickness (P = 0.004), the appearance of a target sign pattern (P = 0.02), irregular patterns of mucosal surface (P = 0.01), and hyperintensity on T1w images (P = 0.03). All MRC criteria except maximal bowel wall thickness were associated with colon weight:length ratio and inflammatory biomarkers (all P < 0.05). Minimal bowel wall thickness and wall signal intensity on T2w images were associated with histological score (P < 0.05).

CONCLUSIONS

MRC is feasible and reliable in rats with TNBS-induced colitis. MRC criteria including colon wall thickness, wall signal intensity on T2w images, hyperintensity in T1w sequence, and the appearance of a target sign pattern may be potential targets for new IBD drugs.

[Computed tomography characteristics of isolated caecal ischaemia]

OBJECTIVE

The aims of this review are to describe the main characteristics for the CT diagnosis of isolated caecal ischaemia (ICA) and give details of the differential diagnosis with other conditions with a similar clinical picture.

MATERIAL AND METHODS

A retrospective study was conducted to review the CT findings of 4 patients diagnosed with ICA in our hospital. The parameters recorded to analyse their characteristics in the CT were: maximum thickness of the caecum wall, the appearance of the peri-caecum fat, presence of free fluid, signs of caecal or portal pneumatosis, the appearance of the caecal appendix, and general signs of the presence of vasculopathy.

RESULTS

In all cases it was recorded that there was a thickening of the walls of the blind loop with an abrupt transition between the caecal wall and the walls of the ascending colon wall. In all cases the caecal thickening had a characteristic image in the central area. Signs of caecal pneumatosis were observed in two cases. All of them had an appendix with normal characteristics.

CONCLUSIONS

The combination of caecal wall thickening with oedematous characteristics, with no changes in the appendix, ileum and colon, suggest the diagnosis of caecal ischaemia, particularly with the presence of pneumatosis.

Glutaraldehyde-induced colitis: case reports and literature review

Glutaraldehyde-induced colitis is an uncommon colitis in clinical practice. Because the involvement of colonic segment is determined by the endoscopic part where glutaraldehyde remains, a recent history of endoscopy and a demarcated involvement of colonic segment are the most characteristic signs of glutaraldehyde-induced colitis. The typical clinical scenario is acute onset of lower abdominal pain, fever, and bloody stool. Laboratory data usually show leukocytosis and elevated C-reactive protein. The endoscopic pictures of involved segments are compatible with acute colitis, including hyperemic, edematous, with or without multiple erosions. Acute ischemic colitis and infectious colitis should be differentiated at the outset of the disease. Stool pathogen tests are usually negative. Parenteral empiric antibiotic may be considered if severe transmural edema of the involved segment is observed in computed tomography. Conservative treatment, including bowel rest and parenteral hydration, is able to stabilize the condition in a week. Herein, we present two cases of acute proctocolitis caused by glutaraldehyde after uneventful colonoscopy.

Multidetector computed tomography in large bowel lesions-a study of 100 cases

This study aims to evaluate the role of multidetector computed tomography (MDCT) in detecting and classifying the large bowel lesions. A prospective study of 100 adult patients was conducted from June 2007 to October 2009. Rectal and IV contrast were used for three dimensional reconstruction. Angiography was performed in cases of suspected ischemic pathology. CT colongraphy was done to evaluate adenomas. CT findings were correlated and confirmed by either colonoscopy, biopsy, postoperative findings or follow-up CT. The pathologies were common in 50-70 yrs (44%). M: F ratio was 2:1. Malignant lesions were seen in (55%) followed by inflammatory lesions in 26%, diverticulitis and ischemic colitis in 6% each. Miscellaneous conditions like polyps, volvulus and intussusceptions were seen in 7%. Adenocarcinoma was the common malignancy (81.2%). Present study showed that adenocarcinomas were associated with marked thickening of bowel wall (>1.5 cm) in 85.4% of patients, asymmetrical wall thickening (96.4%), focal involvement (length <10 cm) in 85.5% with heterogeneous post contrast enhancement (96.3%). Inflammatory lesions showed mild thickening (69%),segmental or diffuse involvement (77%), symmetrical wall thickening (89%) and homogenous post contrast enhancement (81%). Ischemic lesions showed marked thickening (83.4%), symmetrical thickening (100%) and homogenous enhancement (100%). Diverticulitis showed marked thickening (100%), asymmetrical wall thickening (66.7%) with heterogeneous post contrast enhancement (100%), with pericolic fluid. Arterial/venous thrombosis was diagnosed in 66.66%. Three per cent had benign adenomatous polyps on CT colonographic studies. MDCT was accurate in 98.2% cases for differentiating between benign and malignant etiology and is the modality of choice.

Radiologic signs of weapons and munitions: How will noncombatants recognize them?

OBJECTIVE

The purpose of this work was to show the radiologic signs named after weapons and munitions along with their military counterparts to help radiologists recognize these signs, which will allow confident interpretation and diagnosis.

CONCLUSION

Numerous pathologic conditions have classic radiologic manifestations that resemble weapons and ammunition. Most of these signs are highly memorable and easy to recognize. However, the names of the weapons (some of them antique and some not commonly known) may confuse radiologists who are not familiar with the appearance of such weapons as the scimitar, bayonet, or dagger. The value of the signs is reduced if the radiologist is unfamiliar with the appearance of the corresponding weapon.

Role of imaging in vasculitis and connective tissue diseases

Imaging techniques play a pivotal role in securing the diagnosis of large vessel vasculitis, and in demonstrating internal organ involvement in connective tissue diseases. In large vessel vasculitis, angiography is useful in demonstrating vessel stenoses or aneurysms. However, angiography is unable to reveal initial lesions such as vessel wall oedema and thickening, and is thus not useful to make an early diagnosis. In contrast, colour Doppler ultrasonography, computerized tomography angiography, and magnetic resonance imaging/angiography are able to delineate both the vessel wall and the lumen. Therefore, they may show vessel wall alterations when the lumen is still unaffected on angiography. 18fluorodeoxyglucose positron emission tomography does not visualize the vessel wall, but is very sensitive in revealing inflamed vessels. All of these investigations have also been used to follow up patients over time and to monitor response to treatment. In connective tissue diseases, imaging techniques are particularly useful to study internal organs, especially the brain and lung. Magnetic resonance imaging is the investigation of choice to detect and monitor brain disease, while computerized tomography is the best procedure for lung disease. However, since most imaging findings are not entirely specific for any given condition, it is important to interpret the results of imaging in the broader clinical context.

Bowel wall thickening in children: CT findings

A wide variety of bowel diseases, some of which are unique to or more prevalent in pediatric patients, may manifest with intestinal wall thickening at computed tomography (CT). Common causes of bowel wall thickening include edema, hemorrhage, infection, graft-versus-host disease, and inflammatory bowel disease; more unusual causes include immunodeficiencies, lymphoma, hemangioma, pseudotumor, and Langerhans cell histiocytosis. Radiologists must be familiar with the CT signs of bowel disease and should take careful note of the bowel characteristics (eg, extent and distribution of disease involvement, bowel dilatation, mural stratification, perienteric findings) to generate an adequate differential diagnosis. The study should be tailored and optimized in advance according to the clinical scenario to decrease radiation exposure due to repeated or delayed scanning. With spiral CT scanners, studies can be performed quickly, thereby eliminating the need for sedation, and multiple reconstructed images can be generated. CT is an invaluable diagnostic tool in the evaluation of pediatric diseases involving the bowel, in spite of the use of ionizing radiation.

The acute abdomen in the immune compromised host

Recent advances in transplantation, oncology and AIDS therapy have greatly increased life expectancies of patients diagnosed with malignancy, auto-immune disorders and organ failure. However, as this immune compromised population grows, complications of such therapies have become a major source of morbidity and mortality. Classical clinical and laboratory evidence of intra-abdominal pathology may be absent in the immune compromised host. Consequently, the radiologist is increasingly called upon to diagnose acute intra-abdominal complications associated with immunodeficiency. This review explores the aetiology of the acute abdomen in the immune compromised host. The typical radiological appearances of the commonest conditions are illustrated. The challenges and limitations in the radiological diagnosis of these conditions are discussed.

Predicting and monitoring colitis development in mice by micro-computed tomography

BACKGROUND

Computed tomography (CT) has been developed as a tool for monitoring human inflammatory bowel disease (IBD). The aim of this study was to evaluate colon wall thickness as a noninvasive marker in the dextran sodium sulfate (DSS) mouse model of colitis using micro-CT.

METHODS

Mice were examined by micro-CT 1, 2, or 4 times between day 0 (d0) and d26 after induction of colitis to document the kinetics of changes in colon wall thickness and its relation to colitis development.

RESULTS

DSS-treated mice displayed a significantly thicker colon wall at all timepoints (days 5, 8, 12, 19, and 26) investigated compared to healthy controls. Colon wall thickness showed a good correlation to the macroscopic grading of colitis (r = 0.81). The increase in colon wall thickness occurred mainly during the acute phase of colitis (between days 5 and 12) and did not progress much further in the chronic phase of colitis (d26). Colon wall thickness at d26 was thereby predicted by measurements at d12. All mice did not respond equally to DSS and this difference was manifest during the first 2 weeks of colitis, providing an important tool in stratifying responders from nonresponders.

CONCLUSIONS

While the potential impact of handling and anesthesia should be considered on repeated micro-CT, irradiation exposure during repeated micro-CT did not affect the development of colitis. Thus, the results suggest that micro-CT can be used for monitoring and prediction of the inflammatory response in mouse colitis in future therapeutic studies.

Chemical colitis

Chemical colitis can occur as a result of accidental contamination of endoscopes or by intentional or accidental administration of enemas containing various chemicals. Most cases have occurred after accidental contamination of endoscopes with glutaraldehyde and/or hydrogen peroxide. There have been multiple case reports of chemical colitis resulting from unintentional administration of caustic chemicals. Intentional administration of corrosive enemas has been implicated in sexual practices, bowel cleansing, or in suicide attempts. Patients present with nonspecific symptoms including abdominal pain, rectal bleeding, and/or diarrhea. As chemical colitis remains rare, the literature consists of scattered case reports and small series. Agents implicated in chemical colitis that are covered in this review include alcohol, radiocontrast agents, glutaraldehyde, formalin, ergotamine, hydrofluoric acid, sulfuric acid, acetic acid, ammonia, soap, sodium hydroxide, hydrogen peroxide, herbal medicines, chloro-m-xylenol, and potassium permanganate. Clinical, endoscopic, and histologic features are outlined for each agent in addition to the existing literature. Given the nonspecific presentation of many cases of chemically induced colitis, the diagnosis can be challenging if the pertinent history is not obtained. Most patients demonstrate the resolution of chemical-induced colitis after conservative or medical therapy. Depending on the depth and extent of injury, patients rarely require colectomy for ischemic colitis and/or peritonitis. Other postingestion complications include colonic strictures and rectovaginal fistulae. The benefits of medical therapy compared with conservative therapy are not known, as comparative clinical management trials have not been performed.

Pseudomembranous colitis revisited: spectrum of imaging findings

In recent years there has been a marked increase in the incidence of pseudomembranous colitis (PMC). PMC is more common in patients over 65 years of age and can cause significant morbidity. The purpose of this article is to review the imaging features of PMC on plain radiography, sonography, computed tomography (CT), scintigraphy and magnetic resonance imaging (MRI). It is important to recognize the imaging findings of PMC using different imaging methods and encourage urgent confirmation of the diagnosis serologically, as the differential includes other fulminant colitides for which colectomy may be the required. Awareness of the spectrum of imaging findings of PMC can help radiologists make the primary or incidental diagnosis of PMC.