Mesenteric lymph nodes seen at imaging: causes and significance

Mesenteric lymphadenitis as a presenting feature of Whipple's disease

Detecting Whipple’s disease, a “great imitator”, requires a high index of suspicion so that antimicrobial treatment can be initiated in a timely manner; a missed diagnosis can be fatal. Although an uncommon cause, Whipple’s disease must be considered in adults with mesenteric lymphadenitis. We report the case of a 39-year-old African American man who presented with chronic joint pain, chronic weight loss, and acute onset epigastric pain. Contrast-enhanced computed tomography of the abdomen and pelvis showed extensive mesenteric lymphadenopathy. A diagnosis of Whipple’s disease was made based upon demonstration of PAS-positive macrophages in the mesenteric lymph node and duodenal biopsies. Antimicrobial therapy resulted in weight gain and resolution of abdominal pain and arthralgia at six months follow-up.

Whipple’s disease can be fatal without antibacterial therapy and it always needs to be considered in individuals presenting with any combination of abdominal pain, weight loss, and diarrhea in the background of nonspecific arthritis or arthralgia. Whipple’s disease must also be considered in adults presenting with mesenteric lymphadenitis. Review of CT scans may be helpful, as Whipple’s disease characteristically causes low attenuation mesenteric lymphadenopathy.

Magnetic resonance enterography in pediatric celiac disease

OBJECTIVE

To assess if magnetic resonance enterography is capable of showing evidence/extent of disease in pediatric patients with biopsy-proven celiac disease by comparing with a control group, and to correlate the magnetic resonance enterography findings with anti-endomysial antibody level, which is an indicator of gluten-free dietary compliance.

METHODS

Thirty-one pediatric patients (mean age 11.7±3.1 years) with biopsy-proven celiac disease and 40 pediatric patients as a control group were recruited in the study. The magnetic resonance enterography images of both patients with celiac disease and those of the control group were evaluated by two pediatric radiologists in a blinded manner for the mucosal pattern, presence of wall thickening, luminal distention of the small bowel, and extra-intestinal findings. Patient charts were reviewed to note clinical features and laboratory findings. The histopathologic review of the duodenal biopsies was re-conducted.

RESULTS

The mean duration of the disease was 5.6±1.8 years (range: 3-7.2 years). In 24 (77%) of the patients, anti-endomysial antibody levels were elevated (mean 119.2±66.6RU/mL). Magnetic resonance enterography revealed normal fold pattern in all the patients. Ten (32%) patients had enlarged mesenteric lymph nodes.

CONCLUSION

Although a majority of the patients had elevated anti-endomysial antibody levels indicating poor dietary compliance, magnetic resonance enterography did not show any mucosal abnormality associated with the inability of magnetic resonance enterography to detect mild/early changes of celiac disease in children. Therefore, it may not be useful for the follow-up of pediatric celiac disease.

The American College of Radiology Incidental Findings Committee Recommendations for Management of Incidental Lymph Nodes: A Single-Center Evaluation

RATIONALE AND OBJECTIVES

To assess the American College of Radiology Incidental Findings Committee's (ACR-IFC) recommendations for defining and following up abnormal incidental abdominopelvic lymph nodes.

MATERIALS AND METHODS

A total of 59 lymph nodes satisfying ACR-IFC criteria as incidental (no malignancy or lymphoproliferative disorder) and with sufficient follow-up to classify as benign (biopsy, decreased size, ≥12-month stability) or malignant (biopsy, detection of primary malignancy combined with either fluorodeoxyglucose hyperactivity or increase in size of the node) were included. Two radiologists independently assessed nodes for suspicious features by ACR-IFC criteria (round with indistinct hilum, hypervascularity, necrosis, cluster ≥3 nodes, cluster ≥2 nodes in ≥2 stations, size ≥1 cm in retroperitoneum). Outcomes were assessed with attention to ACR-IFC's recommendation for initial 3-month follow-up.

RESULTS

A total of 8.5% of nodes were malignant; 91.5% were benign. Two of six malignant nodes were stable at 3 to <6-month follow-up before diagnosis; diagnosis of four of five malignant nodes was facilitated by later development of non-nodal sites of tumor. A total of 13, 5, 8, and 9 nodes were deemed benign given a decrease at <3 months, 3-5 months, 6-11 months, or ≥12 months of follow-up. No ACR-IFC feature differentiated benign and malignant nodes (P = 0.164-1.0). A cluster ≥3 nodes was present in 88.1%-93.2% of nodes. A total of 96.6%-98.3% had ≥1 suspicious feature for both readers. Necrosis and hypervascularity were not identified in any node.

CONCLUSIONS

ACR-IFC imaging features overwhelmingly classified incidental nodes as abnormal, although did not differentiate benign and malignant nodes. Nodes stable at the ACR-IFC's advised initial 3-month follow-up were occasionally proven malignant or decreased on further imaging. Refinement of imaging criteria to define nodes of particularly high risk, integrated with other clinical criteria, may help optimize the follow-up of incidental abdominopelvic lymph nodes.

Accessory spleen versus lymph node: Value of iodine quantification with dual-energy computed tomography

OBJECTIVES

To evaluate whether iodine quantification with Dual-Energy Computed Tomography (DECT) improves the differentiation of accessory spleens (AS) from lymph nodes (LN) compared to CT number measurements.

METHODS

Abdominal DECT images of 75 patients with either AS (n=35) or LN (n=48) (benign entity) were retrospectively evaluated. Hounsfield Units (HU) and iodine concentrations of AS, LN and the main spleen were measured. Receiver operating characteristics (ROC) were performed to calculate an optimal threshold for distinguishing AS from LN. Sensitivity, specificity, and accuracy were calculated for distinguishing AS from LN by iodine concentration measurements.

RESULTS

Mean CT numbers and iodine concentrations were higher for AS (148±29 HU and 48.2±11×100μg/cc) than LN (83±19 HU and 31.5±6.2×100μg/cc, respectively, P<0.001 each). Mean CT numbers were lower for AS compared to the main spleen (161±29HU, P<0.01), whereas mean iodine concentrations (47.7±10×100μg/cc) were not significantly different (P=0.095). An iodine concentration greater than 38×100μg/cc suggested AS with a sensitivity, specificity and accuracy of 91%, 85%, and 88%, respectively (Area under ROC curve 0.941).

CONCLUSIONS

Iodine measurements might contribute to the differentiation of AS from LN. Iodine concentrations similar to that of the main spleen may help to confirm the diagnosis of AS.

Stable J-aggregation enabled dual photoacoustic and fluorescence nanoparticles for intraoperative cancer imaging

J-aggregates display nanoscale optical properties which enable their use in fluorescence and photoacoustic imaging applications. However, control over their optical properties in an in vivo setting is hampered by the conformational lability of the J-aggregate structure in complex biological environments. J-aggregating nanoparticles (JNP) formed by self-assembly of bacteriopheophorbide-lipid (Bchl-lipid) in lipid nanovesicles represents a novel strategy to stabilize J-aggregates for in vivo bioimaging applications. We find that 15 mol% Bchl-lipid embedded within a saturated phospholipid bilayer vesicle was optimal in terms of maximizing Bchl-lipid dye loading, while maintaining a spherical nanoparticle morphology and retaining spectral properties characteristic of J-aggregates. The addition of cholesterol maintains the stability of the J-aggregate absorption band for up to 6 hours in the presence of 90% FBS. In a proof-of-concept experiment, we successfully applied JNPs as a fluorescence contrast agent for real-time intraoperative detection of metastatic lymph nodes in a rabbit head-and-neck cancer model. Lymph node metastasis delineation was further verified by visualizing the JNP within the excised lymph node using photoacoustic imaging. Using JNPs, we demonstrate the possibility of using J-aggregates as fluorescence and photoacoustic contrast agents and may potentially spur the development of other nanomaterials that can stably induce J-aggregation for in vivo cancer bioimaging applications.

Abdominal manifestations of histiocytic disorders in adults: imaging perspective

Histiocytic disorders (HDs) are a diverse group of diseases characterized by pathologic infiltration of normal tissues by cells of the mononuclear phagocyte system. The spectrum of these diseases ranges from treatable infectious diseases to rapidly progressive, life-threatening conditions. Although they are rare and difficult diagnoses, HDs can be diagnosed with the help of clinical and laboratory analyses, imaging features and tissue biopsy. The clinicopathology and imaging spectrum of select entities belonging to this disorder are presented in this review.

De-misty-fying the mesentery: an algorithmic approach to neoplastic and non-neoplastic mesenteric abnormalities

Mesenteric abnormalities are often incidentally discovered on cross-sectional imaging performed during daily clinical practice. Findings can range from the vague "misty mesentery" to solid masses, and the possible etiologic causes encompass a wide spectrum of underlying pathologies including infectious, inflammatory, and neoplastic processes. Unfortunately, the clinical and imaging findings are often non-specific and may overlap. This article discusses the various diseases that result in mesenteric abnormalities. It provides a framework to non-invasively differentiate these entities, when possible.

Microbiota-Dependent Sequelae of Acute Infection Compromise Tissue-Specific Immunity

Infections have been proposed as initiating factors for inflammatory disorders; however, identifying associations between defined infectious agents and the initiation of chronic disease has remained elusive. Here, we report that a single acute infection can have dramatic and long-term consequences for tissue-specific immunity. Following clearance of Yersinia pseudotuberculosis, sustained inflammation and associated lymphatic leakage in the mesenteric adipose tissue deviates migratory dendritic cells to the adipose compartment, thereby preventing their accumulation in the mesenteric lymph node. As a consequence, canonical mucosal immune functions, including tolerance and protective immunity, are persistently compromised. Post-resolution of infection, signals derived from the microbiota maintain inflammatory mesentery remodeling and consequently, transient ablation of the microbiota restores mucosal immunity. Our results indicate that persistent disruption of communication between tissues and the immune system following clearance of an acute infection represents an inflection point beyond which tissue homeostasis and immunity is compromised for the long-term. VIDEO ABSTRACT.

Non-invasive mapping of deep-tissue lymph nodes in live animals using a multimodal PET/MRI nanoparticle

The invasion status of tumour-draining lymph nodes (LNs) is a critical indicator of cancer stage and is important for treatment planning. Clinicians currently use planar scintigraphy and single-photon emission computed tomography (SPECT) with (99m)Tc-radiocolloid to guide biopsy and resection of LNs. However, emerging multimodality approaches such as positron emission tomography combined with magnetic resonance imaging (PET/MRI) detect sites of disease with higher sensitivity and accuracy. Here we present a multimodal nanoparticle, (89)Zr-ferumoxytol, for the enhanced detection of LNs with PET/MRI. For genuine translational potential, we leverage a clinical iron oxide formulation, altered with minimal modification for radiolabelling. Axillary drainage in naive mice and from healthy and tumour-bearing prostates was investigated. We demonstrate that (89)Zr-ferumoxytol can be used for high-resolution tomographic studies of lymphatic drainage in preclinical disease models. This nanoparticle platform has significant translational potential to improve preoperative planning for nodal resection and tumour staging.

Multimodal Image-Guided Surgical and Photodynamic Interventions in Head and Neck Cancer: From Primary Tumor to Metastatic Drainage

PURPOSE

The low survival rate of head and neck cancer (HNC) patients is attributable to late disease diagnosis and high recurrence rate. Current HNC staging has inadequate accuracy and low sensitivity for effective diagnosis and treatment management. The multimodal porphyrin lipoprotein-mimicking nanoparticle (PLP), intrinsically capable of positron emission tomography (PET), fluorescence imaging, and photodynamic therapy (PDT), shows great potential to enhance the accuracy of HNC staging and potentially HNC management.

EXPERIMENTAL DESIGN

Using a clinically relevant VX-2 buccal carcinoma rabbit model that is able to consistently develop metastasis to regional lymph nodes after tumor induction, we investigated the abilities of PLP for HNC diagnosis and management.

RESULTS

PLPs facilitated accurate detection of primary tumor and metastatic nodes (their PET image signal to surrounding muscle ratios were 10.0 and 7.3, respectively), and provided visualization of the lymphatic drainage from tumor to regional lymph nodes by both preoperative PET and intraoperative fluorescence imaging, allowing the identification of unknown primaries and recurrent tumors. PLP-PDT significantly enhanced cell apoptosis in mouse tumors (73.2% of PLP-PDT group vs 7.1% of PLP alone group) and demonstrated complete eradication of primary tumors and obstruction of tumor metastasis in HNC rabbit model without toxicity in normal tissues or damage to adjacent critical structures.

CONCLUSIONS

PLPs provide a multimodal imaging and therapy platform that could enhance HNC diagnosis by integrating PET/computed tomography and fluorescence imaging, and improve HNC therapeutic efficacy and specificity by tailoring treatment via fluorescence-guided surgery and PDT.

Current radiological strategies for the assessment of right lower quadrant abdominal pain

Right lower quadrant abdominal pain is a common clinical entity. Imaging and the radiologistplay an integral role in achieving a diagnosis, so guiding prompt management of patients.This review discusses the spectrum of pathology and imaging findings, and highlights and contrasts the preferred imaging modalities in different subsets of patients.

CT enterography as a powerful tool for the evaluation of inflammatory activity in Crohn's disease: relationship of CT findings with CDAI and acute-phase reactants

PURPOSE

Few studies have correlated computed tomography enterography (CTE) findings with Crohn's disease (CD) clinical and biochemical activity. The aim of this study was to evaluate correlations between CTE findings with CD activity.

MATERIALS AND METHODS

The CTE datasets from 62 patients were retrospectively reviewed for different parameters: bowel wall thickening and hyperenhancement, mesenteric alterations, abdominal free fluid and complications related to the disease (fistulas, strictures, abscesses). Activity was assessed using the Crohn's Disease Activity Index (CDAI) and some biochemical markers (C-reactive protein, erythrocyte sedimentation rate, alpha 2-globulins, fibrinogen, platelets, haemoglobin). Correlations between CTE parameters, clinical activity score and laboratory parameters were assessed by logistic regression.

RESULTS

CDAI was significantly correlated with increased fat density (p = 0.03) and intestinal strictures (p = 0.04). Platelet counts were elevated in patients with enlarged mesenteric lymph nodes (p = 0.009) and the comb sign (p = 0.05). Serum alpha 2-globulins were higher in the presence of the comb sign (p = 0.03).

CONCLUSION

The CTE finding of perienteric inflammation (increased fat density) and vascular engorgement of the vasa recta in CD patients suggest that the disease is clinically active and that these patients may require more aggressive treatment than patients without these findings.

Contrast enhanced computed tomography characterization of fluorodeoxygluocose-avid regional and non-regional lymph nodes in patients with suspicion of metastatic bladder cancer

Objective:

The objective of this study is to assess if size alone can predict the presence of metastatic disease within lymph nodes seen on contrast enhanced-computed tomography (CE-CT) in patients with suspicion of metastatic bladder cancer and also to evaluate the nodal distribution and morphological characteristics of fluorodeoxygluocose (FDG) avid lymph nodes on CE-CT.

Materials and Methods:

A retrospective analysis from 2002 to 2009 was performed on patients with suspicion of recurrent disease undergoing restaging FDG-positron emission tomography (PET)/CT. Standardized uptake value (SUVmax) adjusted for lean body mass was recorded in abnormal lymph nodes in the abdominopelvic region. Distribution, size, shape, presence of necrosis and clustering of the FDG-avid lymph nodes was assessed on CE-CT obtained within 4 weeks of the PET/CT. The abnormal nodes were then compared with non-FDG avid lymph nodes on the contralateral side serving as control.

Results:

A total of 103 lymph nodes were found to be FDG-avid in 14 patients on 17 PET/CT examinations. Overall, mean SULmax was 4.7 (range: 1.6-10.7), which is significantly higher than background of 1.5 (P < 0.05). Regional pelvic lymph nodes were FDG-avid in 93% of patients and metastatic extra-pelvic in 100% of patients. The overall average size of the FDG avid lymph nodes on CE-CT was 11 mm with a third of these measuring 3-8 mm. The average size of FDG-avid lymph nodes was 11 mm in the paraaortic region 13 mm in the common iliac 9 mm in the internal iliac and 13 mm in the external iliac regions. Nearly 88.4% of lymph nodes were round in shape, clustering was present in 68% and necrosis in 7% and average size of lymph nodes that served as controls was 6 mm with reniform morphology in 92% and absence of clustering and necrosis.

Conclusion:

Overlap in size exists between FDG-avid pathological and non-pathological lymph nodes seen on CE-CT in patients with metastatic bladder cancer. Other characteristic such as abnormal morphology and clustering are useful adjuncts in the evaluation of nodal metastatic disease.

The management of retroperitoneal lymphadenopathy in spermatocytic seminoma of the testicle

Spermatocytic seminoma is an extremely rare clinically and pathologically distinct subtype of testicular cancer that infrequently metastasizes and typically yields a good prognosis. While retroperitoneal lymphadenopathy in the typical testicular cancer patient often harbors metastatic disease, in a patient with spermatocytic seminoma this finding should be viewed with suspicion, and pathologic confirmation of metastatic disease is essential. We present a 49-year-old man with spermatocytic seminoma and retroperitoneal and mesenteric lymphadenopathy who was found to have concurrent low-grade lymphoma.

Cross-sectional imaging of nontraumatic peritoneal and mesenteric emergencies

Multiple nontraumatic peritoneal and mesenteric emergencies are encountered at imaging of patients in the emergency department. Peritoneal and mesenteric emergencies are usually detected in patients in the emergency department during evaluation of nonspecific abdominal pain. A high index of suspicion is required for the establishment of early diagnosis and aversion of life-threatening complications in cases of peritoneal carcinomatosis, nontraumatic hemoperitoneum, and peritonitis. A correct diagnosis of omental infarction, mesenteric adenitis, and mesenteric panniculitis helps patients primarily by avoiding unnecessary surgery. In this review article, we illustrate the cross-sectional imaging appearance of various nontraumatic peritoneal and mesenteric emergencies by emphasizing the role of the emergency radiologist in detecting and managing these entities.

Percutaneous tattoo pigment simulating calcific deposits in axillary lymph nodes

The isolated finding of calcific deposits within axillary lymph nodes on mammography suggests a broad range of differential diagnoses, from benign causes such as granulomatous reaction secondary to previous histoplasmosis infection to malignancies such as breast cancer and metastatic disease from extramammary primary malignancies. Therefore, the isolated finding of intranodal calcium may warrant biopsy for a definitive diagnosis when a benign etiology is not apparent. We present a patient with isolated axillary lymph node densities on mammography and chest computed tomography, which were subsequently proven to represent deposition of tattoo pigment.

Mesenterial, omental, and peritoneal disorders in antiretroviral-treated HIV/AIDS patients: spectrum of cross-sectional imaging findings

In the era of highly active antiretroviral therapy, radiologists are increasingly confronted with a progressively aging HIV-infected population with improved immune function and survival, in whom a wide spectrum of infectious and neoplastic opportunistic disorders may be encountered. Furthermore, HIV / AIDS patients commonly have unspecific symptoms and physical signs, multicentric or coexisting diseases, so that diagnostic imaging studies are crucial to correctly identify and stage HIV-related abnormalities. Currently, volumetric multidetector CT (MDCT) provides comprehensive assessment and confident post-treatment follow-up of opportunistic abnormalities involving the mesentery, omentum, and peritoneum. In this pictorial essay, the cross-sectional imaging appearances of opportunistic disorders involving the mesentery, peritoneum, or both compartments in HIV / AIDS patients are reviewed, with emphasis on those MDCT findings that may be helpful for differential diagnosis along with knowledge of the degree of immune suppression as measured by the CD4 lymphocyte count. Familiarity with the varied spectrum of HIV-related opportunistic disorders encountered in antiretroviral - treated patients and their imaging appearances should allow radiologists to improve their confidence in the characterization of abnormal findings observed on abdominal cross-sectional imaging studies.

Case report: Calcifying fibrous tumor presenting as an asymptomatic pelvic mass

Calcifying fibrous tumor (CFT) is a rare benign mesenchymal tumor most commonly found in the soft tissues of the extremities and pleura. It is characterized by hyalinized collagenous fibrous tissue, with bland spindle cells, psammomatous or dystrophic calcifications, and focal lymphoplasmacytic infiltrate. CFT of the gastrointestinal tract is exceedingly uncommon. We report a case of CFT arising from the small intestine and associated mesentery; this case was identified incidentally in an otherwise healthy 45-year-old man.

Positron lymphography: multimodal, high-resolution, dynamic mapping and resection of lymph nodes after intradermal injection of 18F-FDG

The lymphatic system plays a critical role in the maintenance of healthy tissues. Its function is an important indicator of the presence and extent of disease. In oncology, metastatic spread to local lymph nodes (LNs) is a strong predictor of poor outcome. Clinical methods for the visualization of LNs involve regional injection and tracking of (99m)Tc-sulfur colloid ((99m)Tc-SC) along with absorbent dyes. Intraoperatively, these techniques suffer from the requirement of administration of multiple contrast media ((99m)Tc-SC and isosulfan blue), unwieldy γ-probes, and a short effective surgical window for dyes. Preclinically, imaging of transport through the lymphatics is further hindered by the resolution of lymphoscintigraphy and SPECT. We investigated multimodal imaging in animal models using intradermal administration of (18)F-FDG for combined diagnostic and intraoperative use. PET visualizes LNs with high sensitivity and resolution and low background. Cerenkov radiation (CR) from (18)F-FDG was evaluated to optically guide surgical resection of LNs.

METHODS

Imaging of (18)F-FDG uptake used PET and sensitive luminescent imaging equipment (for CR). Dynamic PET was performed in both sexes and multiple strains (NCr Nude, C57BL/6, and Nu/Nu) of mice. Biodistribution confirmed the uptake of (18)F-FDG and was compared with that of (99m)Tc-SC. Verification of uptake and the ability to use (18)F-FDG CR to guide nodal removal were confirmed histologically.

RESULTS

Intradermal injection of (18)F-FDG clearly revealed lymphatic vessels and LNs by PET. Dynamic imaging revealed rapid and sustained labeling of these structures. Biodistribution of the radiotracer confirmed the active transport of radioglucose in the lymphatics to the local LNs and over time into the general circulation. (18)F-FDG also enabled visualization of LNs through CR, even before surgically revealing the site, and guided LN resection.

CONCLUSION

Intradermal (18)F-FDG can enhance the preclinical investigation of the lymphatics through dynamic, high-resolution, and quantitative tomographic imaging. Clinically, combined PET/Cerenkov imaging has significant potential as a single-dose, dual-modality tracer for diagnostics (PET/CT) and guided resection of LNs (Cerenkov optical).

Imaging of acute right lower quadrant abdominal pain: differential diagnoses beyond appendicitis

Evaluation of acute right lower quadrant pain remains a common and challenging clinical scenario for emergency medicine physicians due to frequent nonspecific signs, symptoms, and physical examination findings. Therefore, imaging has evolved to play a pivotal role in the emergency setting. While appendicitis is a common cause for acute pain, there are numerous other important differential considerations with which the radiologist must be aware. The purpose of this review is to list an anatomy-based, encompassing differential diagnosis in addition to acute appendicitis for right lower quadrant pain; demonstrate the key imaging findings of numerous differential considerations; and describe helpful imaging and clinical features useful in narrowing the differential diagnosis.

Gut barrier dysfunction in the Apc(Min/+) mouse model of colon cancer cachexia

BACKGROUND

The Apc(Min/+) mouse, an animal model of colorectal cancer and cachexia, has a heterologous mutation in the Apc tumor suppressor gene, predisposing the mouse to intestinal and colon tumor development. This mouse develops intestinal polyps by ~4 weeks of age, and loses body weight gradually between ~14 and ~20 weeks of age. The strengths of this cachexia model derive from several features that mimic human cancer, including a gradual increase in tumor burden, chronic inflammation, and anemia. Little is known about the role of gut barrier dysfunction and endotoxemia in the development of cancer cachexia. We sought to determine how gut permeability and resultant endotoxemia change with the progression of cachexia.

METHODS

Intestinal gut barrier integrity was assessed by permeability to FITC-dextran (MW(av)=4000kDa; FD4). Plasma glucose and triglycerides were measured by enzymatic assays, IL-6 by enzyme-linked immunosorbent assay, and endotoxin by the limulus amoebocyte assay. Body temperature was measured using a rectal probe.

RESULTS

Progression of cachexia was accompanied by development of gut barrier dysfunction (permeability to FD4), hypertrophy of mesenteric lymph nodes, and an increase in plasma endotoxin concentration. Changes in blood glucose and glucose tolerance, plasma IL-6, triglycerides, and body temperature were characteristic of endotoxemia.

CONCLUSION

We propose a role for gut barrier dysfunction (GBD) and subsequent endotoxemia in the development of inflammation and progression of cachexia in the Apc(Min/+) mouse.

Beyond appendicitis: common and uncommon gastrointestinal causes of right lower quadrant abdominal pain at multidetector CT

Right lower quadrant abdominal pain is one of the most common causes of a patient visit to the emergency department. Although appendicitis is the most common condition requiring surgery in patients with abdominal pain, right lower quadrant pain can be indicative of a vast list of differential diagnoses and is thus a challenge for clinicians. Other causes of right lower quadrant pain beyond appendicitis include inflammatory and infectious conditions involving the ileocecal region; diverticulitis; malignancies; conditions affecting the epiploic appendages, omentum, and mesentery; and miscellaneous conditions. Multidetector computed tomography (CT) has emerged as the modality of choice for evaluation of patients with several acute traumatic and nontraumatic conditions causing right lower quadrant pain. Multidetector CT is an extremely useful noninvasive method for diagnosis and management of not only the most common causes such as appendicitis but also less common conditions.

Pelvic incidentalomas

Recent advances in multi-detector computed tomography, magnetic resonance imaging, and ultrasound have led to the detection of incidental ovarian, uterine, vascular and pelvic nodal abnormalities in both the oncology and non-oncology patient population that in the past remained undiscovered. These incidental pelvic lesions have created a management dilemma for both clinicians and radiologists. Depending on the clinical setting, these lesions may require no further evaluation, additional immediate or serial follow-up imaging, or surgical intervention. In this review, guidelines concerning the diagnosis and management of some of the more common pelvic incidentalomas are presented.

[Peritoneum and mesenterium. Radiological anatomy and extent of peritoneal diseases]

The abdominal cavity is subdivided into the peritoneal cavity, lined by the parietal peritoneum, and the extraperitoneal space. It extends from the diaphragm to the pelvic floor. The visceral peritoneum covers the intraperitoneal organs and part of the pelvic organs. The parietal and visceral layers of the peritoneum are in sliding contact; the potential space between them is called the peritoneal cavity and is a part of the embryologic abdominal cavity or primitive coelomic duct. To understand the complex anatomical construction of the different variants of plicae and recesses of the peritoneum, an appreciation of the embryologic development of the peritoneal cavity is crucial. This knowledge reflects the understanding of the peritoneal anatomy, deep knowledge of which is very important in determining the cause and extent of peritoneal diseases as well as in decision making when choosing the appropriate therapeutic approach, whether surgery, conservative treatment, or interventional radiology.

Nonvascular mesenteric disease: utility of multidetector CT with 3D volume rendering

Creation of isotropic volumes with submillimeter multidetector computed tomography (CT) has expanded interpretative practice to routinely include two-dimensional (2D) and three-dimensional (3D) postprocessing techniques. Currently, 2D multiplanar reformatting, maximum intensity projection, and 3D volume rendering are available on most workstations. Only volume rendering yields a 3D display that depicts all tissue types from any orientation. Utility is not limited to vascular applications, as 3D volume rendering can be used to evaluate neoplastic, infectious, and inflammatory processes that affect the small-bowel mesentery. Specifically, interactive interpretation of multidetector CT data sets with volume rendering can help characterize nonvascular mesenteric disease, elucidate its extent through more comprehensive display, and facilitate the identification of complications.

The sandwich sign of non-lymphomatous origin

PURPOSE

To investigate the etiologies of the sandwich sign other than lymphoma.

METHOD

The images of 34 patients with sonographic sandwich sign over a 5-year period were retrospectively reviewed. The etiology was based on the pathologic report of mesenteric lymph nodes, or the presence of extensive metastatic disease in case of known advanced primary cancer or disappearance of the sign after specific treatments.

RESULTS

Malignancy accounted for the majority of cases (91%), and was divided into non-Hodgkin's lymphoma (50%) and metastatic carcinomas (41%). Mycobacterium tuberculosis infection was diagnosed in a previously healthy patient, and 2 patients with acquired immunodeficiency syndrome had Mycobacterium avium-complex infection. The sandwich sign was 1 of the initial presentations in 11 cases with newly diagnosed malignancies, including 6 cases of non-Hodgkin's lymphoma and 5 cases of metastatic carcinomas.

CONCLUSION

Metastatic carcinomas, M. avium-complex, and M. tuberculosis infection may produce the sandwich sign. Searching for etiologies other than lymphoma is important in patients presenting with the sandwich sign.

Tuberculosis versus non-Hodgkin’s lymphomas involving small bowel mesentery: Evaluation with contrast-enhanced computed tomography

AIM: To evaluate the specific computed tomography (CT) imaging criteria for differentiating tuberculosis involving the small bowel mesenteric lymph nodes from lymphomas.

METHODS: We retrospectively reviewed the anatomic distribution, CT enhancement patterns of lymphoma in 18 patients with mesenteric tuberculosis and 22 with untreated non-Hodgkin’s lymphomas (NHL) involving small bowel mesentery (SBM). Of the 18 patients with tuberculosis, 9 had purely mesenteric tuberculous lymphadenopathy (TL), and 9 had mesenteric TL accompanied with tuberculous mesenteritis (TLM).

RESULTS: CT showed that tuberculosis and NHL mainly affected lymph nodes in the body and root of SBM. Homogeneously enhanced lymph nodes in the body and root of SBM were found more often in the NHL (P < 0.05). Homogeneously mixed peripheral enhanced lymph nodes in the body of SBM were found more often in mesenteric TL and TLM (P < 0.05). Peripheral enhanced lymph nodes in the root of SBM were found more often in mesenteric TL and TLM (P < 0.01). “Sandwich sign” in the root of SBM was observed more often in NHL (P < 0.05).

CONCLUSION: Anatomic lymph node distribution, sandwich sign and specific enhancement patterns of lymphadenopathy in SBM on CT images can be used in differentiating between tuberculosis and untreated NHL involving SBM.

Forty-slice MDCT enteroclysis: evaluation after oral administration of isotonic solution in Crohn's disease

OBJECTIVE

The aim of this study was to evaluate the accuracy of multidetector computed tomography (MDCT) enteroclysis after oral hyperhydration with isotonic solution in detecting bowel wall alterations in patients with Crohn's disease.

MATERIALS AND METHODS

Twenty-eight patients with a diagnosis of Crohn's disease established by ileocolonoscopy and histology were enrolled in the study; 15 patients with negative ileocolonoscopy served as controls. In all cases, MDCT enteroclysis was performed after oral administration of 2,000 ml of isotonic solution and intravenous administration of N-butylscopolamine. Axial, isotropic multiplanar and volume-rendered reconstructions were used to evaluate bowel wall thickness, ulceration, contrast enhancement, extraparietal involvement and possible complications.

RESULTS

MDCT enteroclysis identified the typical signs of Crohn's disease in 26 patients (92.8%), with sensitivity of 92.8%, specificity of 100%, positive predictive value 100% and negative predictive value 75%.

CONCLUSIONS

MDCT enteroclysis after oral hyperhydration with isotonic solution showed a high level of accuracy in detecting small bowel changes in patients with Crohn's disease. It can be considered a safe and effective alternative to conventional radiography and small-bowel spiral computed tomography enema, especially in patients who refuse nasojejunal intubation.

An emergency diagnostic dilemma: a case of Yersinia enterocolitica colitis mimicking acute appendicitis in a beta-thalassemia major patient: the role of CT and literature review

The role of computed tomography (CT) scanning in a case of Yersinia enterocolitica (YE) enteritis mimicking acute appendicitis in a 34-year-old female patient with beta-thalassemia major is presented. Although the abdominal CT findings on admittance were indicative of acute appendicitis (enlargement of the appendix and thickening of its wall), making appendectomy a likely treatment option, a second CT scan 3 days later was diagnostic for infectious colitis (bowel wall thickening, ulcerations of the colonic mucosa, and fat stranding), and an unnecessary appendectomy was thus avoided. The diagnosis of YE colitis was later confirmed by serology tests.

Granulocytic sarcoma of bowel: CT findings

PURPOSE

To evaluate retrospectively the computed tomographic (CT) findings of granulocytic sarcoma of the bowel.

MATERIALS AND METHODS

The institutional review boards of all participating institutions approved this study and waived the requirement for informed consent. CT scans were retrospectively reviewed in eight patients (seven men, one woman; age range, 23-71 years; mean age, 46 years) with pathologically proved granulocytic sarcoma of the small and/or large bowel. CT findings were evaluated with regard to the sites, morphologic characteristics, and contrast material enhancement patterns of the lesions, along with other ancillary findings (ie, peritoneal and mesenteric infiltration, ascites, lymphadenopathy, bowel perforation, and obstruction).

RESULTS

Eight patients had a total of 13 lesions in the bowel (of which eight were pathologically proved), involving the duodenum (n=1), jejunum (n=2), ileum (n=5), sigmoid colon (n=1), and rectum (n=4); multifocal bowel lesions were noted in four patients. The lesion varied in shape, with wall thickening alone in three of 13 lesions, an intraluminal polypoid mass in four, an exophytic mass in one, and a combination of findings in five. Contrast material enhancement, relative to the back musculature, showed isoattenuation in seven lesions, hyperattenuation in four, and hypoattenuation in two. Five of eight patients had multiple peritoneal masses with diffuse mesenteric or peritoneal infiltration. Ascites was present in six of eight patients; lymphadenopathy (especially in the mesentery), in five; bowel perforation, in two; and bowel obstruction, in one.

CONCLUSION

Granulocytic sarcoma of the bowel is characterized by variability in shape and contrast enhancement and has a high predilection for mesenteric and peritoneal spread.

Hodgkin's and Non-Hodgkin's Lymphomas

The diagnosis and management of lymphoma have undergone significant changes in the past 20 years. For example, new immunophenotypic and molecular methods have replaced traditional histology-based classification schemes for lymphoma. Fluorine-18-deoxyglucose (FDG) positron emission tomography (PET) has evolved into a potent staging tool and prognostic indicator in many kinds of lymphoma. The role of radiation therapy, especially in patients who have early-stage Hodgkin's disease, has changed substantially. The introduction of anti-CD 20 antibody therapy (Rituximab) has improved the treatment of B-cell lymphoma. These changes are linked with higher expectations for imaging, such as detection of more subtle lymphoma manifestations, evaluation of residual changes, and better assessment of early response. This article reviews clinical and radiologic features of both Hodgkin's disease and non-Hodgkin's lymphoma. It also describes the radiologic staging of lymphoma and the emerging role of FDG-PET for assessing lymphoma.

Significance of mesenteric lymphadenopathy after pancreaticoduodenectomy for periampullary carcinomas: evaluation with serial MDCT studies

OBJECTIVE

To evaluate the significance of mesenteric lymphadenopathy arising after pancreaticoduodenectomy (PD) for periampullary carcinomas.

MATERIALS AND METHODS

Serial multidetector CT (MDCT) studies in 44 patients after PD for periampullary carcinomas (Group A) were retrospectively reviewed, the incidence and interval changes of mesenteric lymphadenopathy were evaluated, and comparisons were made with 21 patients who underwent PD for benign diseases (Group B).

RESULTS

In Group A, mesenteric lymphadenopathy was seen in 31 of 44 (70.5%) patients. The short axis diameter of the largest lymph node ranged from 6.2 to 11.5mm (mean+/-S.D.: 8.6+/-1.4mm), and the short-axis-to-long-axis (S/L) ratio ranged from 0.46 to 0.99 (mean+/-S.D.: 0.69+/-0.12). Six of the 31 (19.4%) mesenteric lymphadenopathy cases showed interval increases in size on follow-up studies, and three cases showed new development of mesenteric lymphadenopathy: all of these nine cases had concurrent recurrence in the mesenteric root. In Group B, 11 (52.4%) had mesenteric lymphadenopathy. The short axis diameter of the largest lymph node ranged from 5.6 to 10.9mm (mean+/-S.D.: 8.0+/-1.9mm) and the S/L ratio ranged from 0.48 to 0.93 (mean+/-S.D.: 0.67+/-0.12). Differences in the incidence, short axis diameter and S/L ratio were not significant between Groups A and B (p=0.154, 0.271 and 0.654, respectively).

CONCLUSION

Mesenetric lymphadenopathy after PD less likely reflects recurrence. Lymph node metastasis may be suggested only when coexisting recurrent mass is found in the proximal mesenteric root.