Multidetector-row computed tomography and 3-dimensional computed tomography imaging of small bowel neoplasms: current concept in diagnosis

Bowel Emergencies in Patients With Cancer

Cancer is the second most common cause of death worldwide. Bowel emergencies in patients with cancer are becoming increasingly more prevalent due to advances in cancer therapy and longer overall patient survival. When these patients present acutely, they are often frail and may have pre-existing co-morbidities. This article discusses the imaging features of bowel emergencies commonly encountered in oncological patients in clinical practice. These include chemotherapy related colitis, neutropenia enterocolitis and typhlitis, toxic megacolon, bowel perforation, malignant bowel obstruction and gastrointestinal haemorrhage. The radiologist plays a key role in identifying these oncological emergencies and guiding further management.

Performance of Multidetector Computed Tomography and Negative Versus Positive Enteric Contrast for Evaluation of Gastrointestinal Neuroendocrine Neoplasms

BACKGROUND

Routine computed tomography (CT) scans are thought to have poor performance for detection of gastrointestinal (GI) neuroendocrine neoplasms (NENs), which leads to delayed workup. Detection of even 1 bowel tumor can guide diagnostic workup and management. The purposes of this study were to assess the accuracy of multidetector computed tomography (MDCT) and to compare negative versus positive enteric contrast in detecting at least 1 GI tumor per patient with suspected or confirmed diagnosis of a NEN.

METHODS

This retrospective study included 107 patients with intravenous and oral contrast (65 positive, 40 negative, and 2 no oral contrast) abdominopelvic MDCT. Two abdominal radiologists independently analyzed the CTs for detection and localization of bowel NENs. Surgical pathology was considered the reference standard. Analyses included κ and summary statistics, McNemar test, Pearson χ2 test, and Fisher exact test.

RESULTS

Among the 107 CT scans, there were 30 pathology negative studies and 77 studies with positive pathology for GI NEN. Interreader agreement for CT evaluation was substantial (κ = 0.61). At least 1 GI NEN per patient was detected with 51% to 53% sensitivity, 87% to 93% specificity, 91% to 95% positive predictive value (PPV), 42% negative predictive value, and 63% accuracy for each reader, and 57% accuracy when only the concordant (ie, matching) results of the 2 readers were considered. Computed tomography scans with negative enteric contrast had significantly higher sensitivity for concordant results than CTs with positive enteric contrast (58% vs 30%, P = 0.01). Specificity (100% vs 95%, P = 0.5), PPV (100% vs 93%, P = 0.49), negative predictive value (39% vs 39%, P = 0.99), and accuracy (67% vs 51%, P = 0.10) were not significantly different for negative versus positive enteric contrast for the concordant results. There was no significant difference in GI NEN localization between the readers.

CONCLUSIONS

Routine MDCT with either positive or negative enteric contrast can detect at least 1 GI tumor per patient with more than 90% PPV and more than 50% accuracy in patients suspected of GI NEN. Using negative enteric contrast improves sensitivity for GI NEN versus positive enteric contrast. In addition, there is high accuracy in localizing the bowel tumor with positive or negative enteric contrast, which may guide surgery. Radiologists should have heightened awareness that evaluating such scans closely may lead to detection of primary bowel NENs at a higher rate than previously reported.

Imaging Spectrum of Duodenal Emergencies

The duodenum, the first portion of the small bowel, is divided into four segments and extends to both retro- and intraperitoneal spaces. Some conditions arise primarily from the duodenum, but it can be secondarily affected by processes that involve neighboring structures. When duodenal emergencies are not identified and treated promptly, they may result in high morbidity and mortality. Imaging plays an important role in the diagnosis of duodenal conditions in the acute setting. However, the radiologic findings can be subtle, and awareness of relevant patient history and clinical presentation is important as it may increase the index of suspicion and one's ability to diagnose these conditions. Duodenal peptic disease is common and can be complicated by bleeding and perforation. The duodenum can be secondarily involved by pancreatitis and gallbladder pathologic conditions and may be affected by iatrogenic complications following endoscopic procedures. Traumatic injuries to the duodenum are generally uncommon, with penetrating traumatic injury being the most frequent mechanism of injury. Duodenal vascular pathologic conditions such as aortoduodenal fistula are uncommon but can be life threatening. The knowledge of which pathologic condition can involve which duodenal segment can help the radiologist establish a differential diagnosis and achieve a more targeted imaging approach. The online slide presentation from the RSNA Annual Meeting is available for this article. ^©RSNA, 2020.

Value of 18F-FDG PET/CT in patients with hepatic metastatic carcinoma of unknown primary

PURPOSE

This retrospective study aimed to investigate the clinical value of -deoxy-2-(F)-fluorodeoxyglucose positron emission tomography/computed tomography (F-FDG PET/CT) in detecting primary lesions of hepatic metastases.

METHODS

A total of 124 patients with hepatic metastatic carcinoma of unknown primary underwent whole body F-FDG PET/CT imaging. According to the final diagnoses for both primary sites and hepatic metastases that were confirmed either histopathologically or by clinical follow up, all patients were divided into 4 groups: a true positive group (TP, 95 cases), a false positive group (FP, 9), a true negative group (TN, 8) and a false negative group (FN, 12).

RESULTS

The TP rate of primary lesions, detected by F-FDG PET/CT, was 76.61%, the FP rate 7.26%, the TN rate 6.45% and the FN rate 9.68%. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of F-FDG PET/CT in the detection of primary tumors were 88.78%, 52.94%, 91.35%, 40%, and 83.06%, respectively. Accurate diagnosis groups (TP, TN) showed a significantly higher SUVmax (standard uptake maximum value) level than that in error diagnosis groups (FP, FN). The SUVmax between hepatic metastases and primary lesions had a positive correlation. The primary tumor sites of hepatic metastases were mainly located in the gastrointestinal organs and the lungs.

CONCLUSIONS

Whole body F-FDG PET/CT imaging was sensitive for detecting primary sites/lesions with hepatic metastatases of unknown primary, especially when the SUVmax of hepatic metastases were greater than 4.7.

Duodenal emergencies: utility of multidetector CT with 2D multiplanar reconstructions for challenging but critical diagnoses

Duodenal pathology is an infrequent cause of acute abdominal pain for which patients present to the emergency department. Critical pathology on multidetector CT (MDCT) may be overlooked if the radiologist does not carefully evaluate the duodenum as part of the search pattern. Optimal MDCT protocols include intravenous contrast with multiplanar reconstructions (MPRs). A variety of etiologies ranging from infection to malignancy can involve the duodenum, for which interrogation with MPRs is most helpful given the anatomy and complex relationship with surrounding structures. The purpose of this review article is to highlight the importance of CT acquisition with multiplanar reconstructions and review the spectrum of emergent duodenal pathology, with the goal of ensuring accurate and timely diagnosis to best guide patient management.

Tumors of the jejunum and ileum: a pattern-based imaging approach on CT

Since a broad spectrum of tumors can occur in the small bowels, it is not easy to make a correct differential diagnosis among small bowel tumors on CT findings. Therefore, once a mass is detected on CT, the radiologist needs to analyze the mass based on presenting patterns such as location, multiplicity, morphology, and enhancement patterns. In this article, we will illustrate various kinds of small bowel tumors based on imaging patterns at CT to facilitate making a correct diagnosis.

Clinical time course and CT detection of metastatic disease to the small bowel

PURPOSE

The purpose of this study was to identify the CT characteristics of metastatic disease of the small bowel and define the clinical time course between primary tumor diagnosis and small bowel metastasis detection.

METHODS

A retrospective search of a pathologic database for metastases to small bowel identified 242 cases. Exclusion criteria were cases without CT (N = 49), serosal or mesenteric metastases (N = 114), or cases of direct invasion to small bowel (N = 63). The clinical records and imaging were reviewed for 16 patients.

RESULTS

Melanoma was the most common malignancy to metastasize to small bowel (7 of 16 patients). Only one of the 16 cases was detected at the time of initial diagnosis of their primary malignancy. The average time from diagnosis of the primary malignancy or remission to the time of detection of the small bowel metastasis was 7.2 and 8.3 years, respectively. The most common symptoms were gastrointestinal bleeding (N = 5) and small bowel obstruction (N = 5). In 3 cases, the masses were not identified on pre-operative CT.

CONCLUSION

Metastases to the small bowel often occur many years after the initial diagnosis of the primary malignancy or entering remission and may be symptomatic. Attention to the small bowel is particularly important in melanoma patients, who may have multiple small bowel metastases, even after many years of being disease free. As oncology patients undergo numerous surveillance scans and improved therapies allow for longer survival, detection of these masses at a small size can facilitate elective resection to avert urgent surgical intervention.

Multimodality imaging of small bowel neoplasms

Although the small intestine accounts for over 90% of the surface area of the alimentary tract, tumors of the small intestine represent less than 5% of all gastrointestinal tract neoplasms. Common small bowel tumors typically are well evaluated with cross-sectional imaging modalities such as CT and MR, but accurate identification and differentiation can be challenging. Differentiating normal bowel from abnormal tumor depends on imaging modality and the particular technique. While endoscopic evaluation is typically more sensitive for the detection of intraluminal tumors that can be reached, CT and MR, as well as select nuclear medicine studies, remain superior for evaluating extraluminal neoplasms. Understanding the imaging characteristics of typical benign and malignant small bowel tumors is critical, because of overlapping features and associated secondary complications.

Cinematic rendering of small bowel pathology: preliminary observations from this novel 3D CT visualization method

3D visualization methods for volumetric CT data have played an important role in diagnostic imaging of the small bowel, a structure which intrinsically crosses numerous slices in any 2D imaging plane. Recently, a new approach to 3D CT image creation has become available-cinematic rendering (CR). CR differs from other 3D methods in making use of a global lighting model that produces high surface detail and realistic shadowing effects that lead to 3D visualizations with photorealistic quality. Although the utility of these images for improving diagnostic accuracy has not yet been established, our group's early experience in regions of complex anatomy and pathology has been encouraging. In this pictorial review, we review the established role of 3D CT in many of the most common small bowel pathologies, provide examples of those pathologies visualized with CR, and suggest future directions for researchers to pursue.

Utility of CT oral contrast administration in the emergency department of a quaternary oncology hospital: diagnostic implications, turnaround times, and assessment of ED physician ordering

PURPOSE

To compare studies with and without oral contrast on performance of multidetector computed tomography (CT) and the order to CT examination turnaround time in cancer patients presenting to the emergency department (ED). To the best of our knowledge, oral contrast utility has not previously been specifically assessed in cancer patients presenting to the emergency department.

MATERIALS & METHODS

Retrospective review of CT abdomen examinations performed in oncology patients presenting to the emergency department during one month. CT examinations performed with and without oral contrast were rated by two consensus readers for degree of confidence and diagnostic ability. Correlations were assessed for primary cancer type, age, sex, chief complaint/examination indication, body mass index, intravenous contrast status, repeat CT examination within 4 weeks, and disposition. Turnaround times from order to the start of the CT examination were calculated.

RESULTS

The studied group consisted of 267 patients (127 men and 140 women) with a mean age of 56 years and a mean body mass index of 27.8 kg/m². One hundred sixty CT examinations were performed without oral contrast, and 107 CT examinations were performed with oral contrast. There was no significant difference between cases with oral contrast and cases without oral contrast in the number of cases rated as "improved confidence" (odds ratio [OR] 0.54, 95% confidence interval [CI] 0.23-1.31, P = 0.17), "improved diagnosis" (OR 0.58, 95% CI 0.20-1.64, P = 0.3), "impaired confidence" (OR 3.92, 95% CI 0.46-33.06, P = 0.21), or "impaired diagnosis" (OR 2.63, 95% CI 0.29-23.89, P = 0.39). The turnaround time in the group receiving oral contrast (mean, 141 min; standard deviation, 49.8 min) was significantly longer than that in the group not receiving oral contrast (mean, 109.2 min; standard deviation, 64.8 min) with a mean difference of 31.8 min (P < 0.0001).

CONCLUSION

On the basis of our findings and prior studies, targeted rather than default use of oral contrast shows acceptable diagnostic ability in the emergency setting for oncology patients. Benefit from oral contrast use is suggested in scenarios such as suspected fistula/bowel leak/abscess, hypoattenuating peritoneal disease, prior bowel surgery such as gastric bypass, and the absence of intravenous contrast administration. Improvement through the use of targeted oral contrast administration also supports the emergency department need for prompt diagnosis and disposition.

Multidetector CT enterography of focal small bowel lesions: a radiological-pathological correlation

Focal small bowel lesions present a diagnostic challenge for both the radiologist and gastroenterologist. Both the detection and characterization of small bowel masses have greatly improved with the advent of multidetector CT enterography (MD-CTE). As such, MD-CTE is increasingly utilized in the workup of occult gastrointestinal bleeding. In this article, we review the spectrum of focal small bowel masses with pathologic correlation. Adenocarcinoma, the most common primary small bowel malignancy, presents as a focal irregular mass occasionally with circumferential extension leading to obstruction. Small bowel carcinoid tumors most commonly arise in the ileum and are characterized by avid enhancement and marked desmoplastic response of metastatic lesions. Aneurysmal dilatation of small bowel is pathognomonic for lymphoma and secondary findings of lymphadenopathy and splenomegaly should be sought. Benign small bowel masses such as leiomyoma and adenoma may be responsible for occult gastrointestinal bleeding. However, primary vascular lesions of the small bowel remain the most common cause for occult small bowel gastrointestinal bleeding. The arterial phase of contrast obtained with CTE aids in recognition of the vascular nature of these lesions. Systemic conditions such as Peutz-Jeghers syndrome and Crohn's disease may be suggested by the presence of multiple small bowel lesions. Lastly, potential pitfalls such as ingested material should be considered when faced with focal small bowel masses.

Small bowel neoplasms: enhancement patterns and differentiation using post-contrast multiphasic multidetector CT

PURPOSE

The purpose of the present study was to analyze the enhancement patterns of small bowel neoplasms on post-contrast multiphasic multidetector CT and to assess the diagnostic capacity for differentiating five tumor types.

METHODS

We performed a retrospective study of data on 92 small bowel neoplasms. The neoplasms were categorized into five groups according to pathology findings, not imaging findings (23 adenocarcinomas; 22 lymphomas; 19 metastases; 18 gastrointestinal stromal tumors [GIST]; 10 neuroendocrine tumors [NET]).

RESULTS

GIST and NET demonstrated a hypervascular pattern in the multiphasic dynamic study. Adenocarcinoma and lymphoma showed a delayed enhancement pattern. Metastasis was classified as an intermediate enhancement pattern. The receiver operating characteristic analyses revealed that attenuation thresholds could be set with acceptable accuracies for most of the small bowel neoplasms.

CONCLUSIONS

Multiphasic dynamic studies may have the potential to improve the diagnostic capacity of multidetector CT for small bowel neoplasms.

Small Bowel Stromal Tumors: Different Clinicopathologic and Computed Tomography Features in Various Anatomic Sites

Gastrointestinal stromal tumors (GISTs) can present with different clinical and immunohistochemical characteristics according to different anatomic sites. The aim of this study was to compare clinicopathologic and computed tomography (CT) features of small bowel stromal tumors located in the duodenum, jejunum, and ileum. In total, 197 patients (109 male, 88 female) with small bowel GISTs were retrospectively reviewed. All tumors had definite anatomic sites in the small bowel tract with surgical confirmation. The clinicopathologic variables included age, sex, onset of symptoms, and tumor risk category. CT variables included tumor size, degree enhancement, enhancement pattern (region of necrosis), adjacent tissue involvement, lymphadenopathy, and distant metastasis. We assessed any possible differences according to different GIST site of origin. Based on tumor size and mitotic count, the risk categories in different anatomic sites did not differ significantly between duodenal and jejunal GISTs. However, high risk ileum GISTs accounted for 66.0% of ileal cases, which was higher than duodenum cases (36.8%, P = 0.002) and jejunum cases (43.9%, P = 0.004). The mean size of GISTs in the ileum was 9.77 cm, which was significantly larger than in the duodenum (7.41 cm, P = 0.043), and in the jejunum (8.14 cm, P = 0.027). On CT images, enhancement degree appeared to gradually increase from the duodenum to the ileum in the portal phase, and the enhancement pattern presented a tendency for heterogeneity. In Conclusions, the clinicopathologic and CT features of small bowel GISTs can differ according to different primary anatomic sites.

MDCT and clinicopathological features of small bowel gastrointestinal stromal tumours in 102 patients: a single institute experience

OBJECTIVE

Small bowel (SB) is the second most common site of gastrointestinal stromal tumours (GISTs). We evaluated clinical presentation, pathology, imaging features and metastatic pattern of SB GIST.

METHODS

Imaging and clinicopathological data of 102 patients with jejunal/ileal GIST treated at Dana-Farber Cancer Institute and Brigham and Women's Hospital (Boston, MA) between 2002 and 2013 were evaluated. Imaging of treatment-naive primary tumour (41 patients) and follow-up imaging in all patients was reviewed.

RESULTS

90/102 patients were symptomatic at presentation, abdominal pain and lower gastrointestinal blood loss being the most common symptoms. On pathology, 21 GISTs were low risk, 17 were intermediate and 64 were high risk. The mean tumour size was 8.5 cm. On baseline CT (n = 41), tumours were predominantly well circumscribed, exophytic and smooth/mildly lobulated in contour. Of 41 tumours, 16 (39%) were homogeneous, whereas 25 (61%) were heterogeneous. Of the 41 tumours, cystic/necrotic areas (Hounsfield units < 20) were seen in 16 (39%) and calcifications in 9 (22%). CT demonstrated complications in 13/41 (32%) patients in the form of tumour-bowel fistula (TBF) (7/41), bowel obstruction (4/41) and intraperitoneal rupture (2/41). Amongst 102 total patients, metastases developed in 51 (50%) patients (27 at presentation), predominantly involving peritoneum (40/102) and liver (32/102). 7/8 (87%) patients having intraperitoneal rupture at presentation developed metastases. Metastases elsewhere were always associated with hepatic/peritoneal metastases. At last follow-up, 28 patients were deceased (median survival, 65 months).

CONCLUSION

SB GISTs were predominantly large, well-circumscribed, exophytic tumours with or without cystic/necrotic areas. Complications such as TBF, bowel obstruction and intraperitoneal perforation were visualized at presentation, with patients with perforation demonstrating a high risk of metastatic disease. Exophytic eccentric bowel wall involvement and lack of associated adenopathy are useful indicators to help differentiate GISTs from other SB neoplasms.

ADVANCES IN KNOWLEDGE

SB GISTs are predominantly large, well-circumscribed, exophytic tumours, and may present with complications. They often are symptomatic at presentation, are high risk on pathology and metastasize to the peritoneum more commonly than the liver.

Improvement of distension and mural visualization of bowel loops using neutral oral contrasts in abdominal computed tomography

AIM: To assess and compare the image quality of 4% sorbitol and diluted iodine 2% (positive oral contrast agent) in abdomino-pelvic multi-detector computed tomography.

METHODS: Two-hundred patients, referred to the Radiology Department of a central educational hospital for multi-detector row abdominal-pelvic computed tomography, were randomly divided into two groups: the first group received 1500 mL of 4% sorbitol solution as a neutral contrast agent, while in the second group 1500 mL of meglumin solution as a positive contrast agent was administered in a one-way randomized prospective study. The results were independently reviewed by two radiologists. Luminal distension and mural thickness and mucosal enhancement were compared between the two groups. Statistical analysis of the results was performed by Statistical Package for the Social Sciences software version 16 and the Mann-Whitney test at a confidence level of 95%.

RESULTS: Use of neutral oral contrast agent significantly improved visualization of the small bowel wall thickness and mural appearance in comparison with administration of positive contrast agent (P < 0.01). In patients who received sorbitol, the small bowel showed better distention compared with those who received iodine solution as a positive contrast agent (P < 0.05).

CONCLUSION: The results of the study demonstrated that oral administration of sorbitol solution allows better luminal distention and visualization of mural features than iodine solution as a positive contrast agent.

Abdominal and pelvic CT: is positive enteric contrast still necessary? Results of a retrospective observational study

PURPOSE

Evaluation of diagnostic accuracy of abdominal CT depending on the type of enteric contrast agent.

METHODS AND MATERIALS

Multislice CTs of 2,008 patients with different types of oral preparation (positive with barium, n = 576; neutral with water, n = 716; and no enteric contrast, n = 716) were retrospectively evaluated by two radiologists including delineation of intestinal segments and influence on diagnosis and diagnostic reliability exerted by the enteric contrast, using a three-point scale. Furthermore, diagnostic reliability of the delineation of selected enteric pathologies was noted. CT data were assigned into groups: oncology, inflammation, vascular, pathology, trauma and gastrointestinal pathology.

RESULTS

Delineation of the bowel was clearly practicable across all segments irrespective of the type of enteric contrast, though a slight impairment was observed without enteric contrast. Although delineation of intestinal pathologies was mostly classified "clearly delimitable" more difficulties occurred without oral contrast (neutral/positive/no contrast, 0.8 %/3.8 %/6.5 %). Compared to examinations without enteric contrast, there was a significant improvement in diagnosis that was even increased regarding the reader's diagnostic reliability. Positive opacification impaired detection of mucosal enhancement or intestinal bleeding.

CONCLUSION

Water can replace positive enteric contrast agents in abdominal CTs. However, selected clinical questions require individual enteric contrast preparations. Pathology detection is noticeably impaired without any enteric contrast.

Malignant tumours of the small intestine

Adenocarcinoma, neuroendocrine tumours, sarcomas and lymphomas are the four most common malignant tumours arising in the small intestine, although over forty different histological subtypes are described. Collectively these account for only 2% of cancers of the digestive system. The incidence of small bowel cancer has increased in recent decades with a four-fold increase in carcinoid tumours. Risk factors for small bowel tumours include coeliac disease, inflammatory bowel disease and a number of genetic abnormalities. The non-specific nature of their symptoms and the difficulty in visualising these tumours with normal endoscopic techniques often results in late diagnosis. Furthermore the paucity of literature on this topic has made it difficult to standardise management. There has however been marked improvement in imaging methods resulting in earlier diagnosis in many cases. As expected, early detection of localised, well differentiated tumours followed by surgical resection with negative margins offers the best chance of long term survival. Better adjuvant treatment, notably for gastrointestinal stromal tumours, has improved 5-year survival rates significantly. Development of surveillance guidelines for at risk populations may be a valuable way of improving early diagnosis of this challenging group of conditions.

Quantitative and qualitative bowel analysis using mannitol, water and iodine-based endoluminal contrast agent on 64-row detector CT

OBJECTIVE

To assess the performance of mannitol as a luminal contrast as compared to water and positive contrast in evaluation of bowel on multidetector computed tomography (MDCT).

MATERIALS AND METHODS

Three hundred patients were randomly selected for this study and were divided equally into three groups. Each subject received 1500 ml of oral contrast. Group 1 received 3% mannitol in water, group 2 received diluted iodinated positive contrast, and group 3 received plain water without additives. Qualitative and quantitative analysis for distension, fold visibility, and overall image quality were analyzed by actual diameter measurement and point scale system at different bowel levels. One-way analysis of variance (ANOVA) followed by Tukey's HSD Post-hoc test and Pearson's Chi-square (exact test) test were applied.

RESULTS

Group 1 showed better results for small bowel distension, intraluminal homogeneity, and visibility of mucosal folds on quantitative and qualitative analysis with statistically significant P value (P<0.001). The ileo-caecal junction distension and mural feature visibility was better with mannitol (P < 0.001). No significant difference in distension of stomach and duodenum was found between the three groups.

CONCLUSION

Mannitol as endoluminal contrast increases the diagnostic accuracy of the investigative studies in comparison to water and iodine-based contrast by producing significantly better bowel distension and visibility of mural features with improved image quality without additional adverse effects.

MDCT of primary, locally recurrent, and metastatic duodenal gastrointestinal stromal tumours (GISTs): a single institution study of 25 patients with review of literature

AIM

To describe the multidetector computed tomography (MDCT) features of primary, locally recurrent, and metastatic duodenal gastrointestinal stromal tumours (GISTs).

MATERIALS AND METHODS

In this institutional review board-approved, Health Insurance Portability and Accountability Act of 1996 (HIPAA)-compliant, retrospective study, 25 patients [13 men, 12 women; mean age 56 years (34-74 years)] with histopathologically confirmed duodenal GISTs seen at Dana Farber Cancer Institute and Brigham and Women's Hospital from December 1999 to October 2009 were identified. The MDCT of primary tumours in six patients and follow-up imaging in all the 25 patients was reviewed by two radiologists in consensus. Electronic medical records were reviewed to document the clinical characteristics and management.

RESULTS

The mean size of the primary tumour was 3.7 cm (range 2.5-5.6 cm). Three of six primary tumours were in the second and third portions of the duodenum, one in the third portion, one in the third and fourth portions, and one in the fourth portion. Three of six of the tumours were exophytic, two were both exophytic and intraluminal, and one was intramural. The tumours were well-circumscribed, round or oval masses, with few lobulations, and were either homogeneously hyper-enhancing or heterogeneously isodense at MDCT. None of the tumours had necrosis, haemorrhage, calcification, or loco regional lymphadenopathy on imaging. Sixteen of 25 (64%) patients developed metastatic disease, the most common sites being liver (14/16; 87.5%) and peritoneum (5/16; 31%).

CONCLUSION

Duodenal GISTs are well-circumscribed, round or oval masses, and occur in the second through fourth portions of the duodenum, without lymphadenopathy or duodenal obstruction. Duodenal GISTS metastasize frequently to the liver and peritoneum.

Current status of PET/CT in the diagnosis and follow up of lymphomas

Lymphomas are a heterogeneous group of malignancies that have a distinct biological behavior according to the subtype and degree of differentiation. Adequate staging, which has a direct impact on prognosis, is essential to properly plan therapy. Structural cross-sectional imaging, such as computed tomography, has been the standard imaging tool to stage and monitor patients with lymphoma. However, molecular imaging such as positron emission tomography has shown complementary diagnostic and prognostic values. This review discusses the current value of positron emission tomography imaging using 2-[fluorine-18]fluoro-2-deoxy-d-glucose in staging, restaging, monitoring and detecting relapse in Hodgkin's and non-Hodgkin lymphoma.

Carcinoid tumors of the small-bowel: evaluation with 64-section CT-enteroclysis

PURPOSE

To describe the imaging presentation of carcinoid tumors of the small-bowel at 64-section CT-enteroclysis and determine the sensitivity of this technique for tumor detection.

PATIENTS AND METHODS

The 64-section CT-enteroclysis examinations of 22 patients with histopathologically proven small-bowel carcinoid tumors and those of 6 patients with suspected recurrence after small-bowel resection for carcinoid tumor were reviewed. Images were analyzed with respect to imaging presentation. Sensitivity, specificity, and accuracy, of 64-section CT-enteroclysis for the diagnosis of carcinoid tumor of the small-bowel were estimated with 95% confidence intervals (CIs).

RESULTS

Twenty-five carcinoid tumors were confirmed in 22 patients (prevalence, 22/28; 79%). Overall sensitivity for carcinoid tumor detection was 76% (19/25; 95%CI: 55-91%) on a per-lesion basis. On a per-patient basis, 64-section CT-enteroclysis had a sensitivity of 86% (19/22; 95%CI: 65-97%), a specificity of 100% (6/6; 95%CI: 54-100%) and an accuracy of 89% (25/28; 95%CI: 72-98%) for the diagnosis of carcinoid tumor. Focal small-bowel wall thickening, mesenteric stranding, and mesenteric mass were found in 20/22 (91%), 18/22 (82%) and 15/22 (68%) patients with pathologically confirmed tumors.

CONCLUSION

64-Section CT-enteroclysis shows highly suggestive features for the diagnosis of carcinoid tumor of the small-bowel and achieves high degrees of sensitivity for tumor detection.

Malignant tumours of the small intestine: a review of histopathology, multidetector CT and MRI aspects

Small bowel neoplasms, including adenocarcinoma, carcinoid tumour, lymphoma and gastrointestinal stromal tumours, represent a small percentage of gastrointestinal cancers, yet are among those with the poorest prognosis compared with other gastrointestinal malignancies. Unclear clinical scenarios and difficult radiological diagnosis often delay treatment with negative effects on patient survival. Recently, multidetector CT (MDCT) and MRI have been introduced as feasible and accurate diagnostic techniques for the identification and staging of small bowel neoplasms. These techniques are gradually replacing conventional barium radiography as the tool of choice. However, the inherent technical and physiological challenges of small bowel imaging require a familiarity with patient preparation and scan protocols. Adequate knowledge of the histopathology and natural evolution of small bowel neoplasms is also important for differential diagnosis. The aim of this article is to review MDCT and MRI protocols for the evaluation of small bowel tumours and to provide a concise yet comprehensive guide to the most relevant imaging features relative to histopathology.

Positive enteric contrast material for abdominal and pelvic CT with automatic exposure control: what is the effect on patient radiation exposure?

OBJECTIVE

To assess the effect of positive enteric contrast administration on automatic exposure control (AEC) CT radiation exposure in (1) a CT phantom, and (2) a retrospective review of patients.

MATERIALS AND METHODS

We scanned a CT phantom containing simulated bowel that was sequentially filled with water and positive enteric contrast, and recorded the mean volume CT dose index (CTDIvol). We also identified 17 patients who had undergone 2 technically comparable CT scans of the abdomen and pelvis, one with positive enteric contrast and the other with oral water. Paired Student's t-tests were used to compare the mean CTDIvol between scans performed with and without positive enteric contrast. Both the phantom and patient CT scans were performed using AEC with a fixed noise index.

RESULTS

The mean CTDIvol for the phantom with simulated bowel containing water and positive enteric contrast were 8.2 ± 0.2 mGy, and 8.7 ± 0.1 mGy (6.1% higher than water, p=0.02), respectively. The mean CTDIvol for patients scanned with oral water and with positive enteric contrast were 11.8 mGy and 13.1 mGy, respectively (p=0.003). This corresponded to a mean CTDIvol which was 11.0% higher (range: 0.0-20.7% higher) in scans with positive enteric contrast than those with oral water in patients.

CONCLUSIONS

When automatic exposure control is utilized for abdominopelvic CT, the radiation exposure, as measured by CTDIvol, is higher for scans performed with positive enteric contrast than those with oral water.

Obscure gastrointestinal bleeding: diagnostic performance of multidetector CT enterography

PURPOSE

To evaluate the diagnostic performance of computed tomographic (CT) enterography in identifying the source of obscure gastrointestinal bleeding and to determine clinical features associated with a higher diagnostic yield of CT enterography.

MATERIALS AND METHODS

The institutional review board approved this study, with waiver of informed consent. CT enterographic images in 65 patients (46 men [mean age, 54 years; range, 18-85 years] and 19 women [mean age, 62.1 years; range, 33-79 years]) who presented with obscure gastrointestinal bleeding between August 2005 and July 2007 were reviewed retrospectively and independently by two radiologists. The diagnostic performance of CT enterography was assessed by using the results of endoscopic and other imaging examinations, surgery, and clinical follow-up as the reference standard. Differences in the diagnostic yield of CT enterography according to patient demographic and clinical features, including age, sex, type and episode of bleeding (occult, initial overt, and recurrent overt), occurrence of recent bleeding, and history of massive bleeding, were evaluated by using univariate and multivariate logistic regression analyses.

RESULTS

CT enterography helped identify the source of obscure gastrointestinal bleeding in 16 (24.6%) of 65 patients. The sensitivity, specificity, positive predictive value, and negative predictive value of CT enterography were 55.2% (16 of 29), 100% (32 of 32), 100% (16 of 16), and 71.1% (32 of 45), respectively. Among patients' clinical features, a history of massive bleeding (diagnostic yield, 58.3% [seven of 12]; adjusted odds ratio, 7.2; P = .01) was independently associated with a higher diagnostic yield for CT enterography.

CONCLUSION

CT enterography has a potential role in the evaluation of obscure gastrointestinal bleeding. Despite the limited sensitivity of CT enterography, positive CT enterographic findings can reliably indicate the true source of obscure gastrointestinal bleeding. CT enterography is particularly effective in helping identify the source of bleeding in patients with a history of massive bleeding.

SUPPLEMENTAL MATERIAL

http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101936/-/DC1.

Imaging of malignant neoplasms of the mesenteric small bowel: new trends and perspectives

This article describes the recent advances in radiological imaging of malignant neoplasms of the mesenteric small bowel and provides an outline of new trends and perspectives that can be anticipated. The introduction of multidetector row technology, which allows the acquisition of submillimeter and isotropic voxels, has dramatically improved the capabilities of computed tomography in the investigation of the mesenteric small bowel. This technology combined with optimal filling of small bowel loops through the use of appropriate enteral contrast agents has markedly changed small bowel imaging. Computed tomography-enteroclysis, which is based on direct infusion of enteral contrast agent into the mesenteric small bowel through a naso-jejunal tube, provides optimal luminal distension. By contrast, computed tomography-enterography is based on oral administration of enteral contrast agent. These two techniques are now well-established ones for the detection and the characterization of small bowel neoplasms. During the same time, combining the advantages of unsurpassed soft tissue contrast and lack of ionizing radiation, magnetic resonance imaging has gained wide acceptance for the evaluation of patients with suspected small bowel neoplasms. Rapid magnetic resonance imaging sequences used in combination with specific enteral contrast agents generate superb images of the mesenteric small bowel so that magnetic resonance-enteroclysis and magnetic resonance-enterography are now considered as effective diagnostic tools for both the detection and the characterization of neoplasms of the mesenteric small bowel. Recent improvements in image post-processing capabilities help obtain realistic three-dimensional representations of tumors and virtual enteroscopic views of the small bowel that are useful for the surgeon and the gastroenteroenteologist to plan surgical or endoscopic interventions. Along with a better knowledge of the potential and limitations of wireless capsule endoscopy and new endoscopic techniques, these recent developments in radiological imaging reasonably suggest that substantial changes in the investigation of small bowel tumors may be anticipated in a near future, thus potentially create a new paradigm shift after standard small bowel follow-through study has been universally abandoned.

New progress in CT and MRI examination and diagnosis of small intestinal tumors

Precise examination and diagnosis of small intestinal tumors is difficult because of the curved course and overlapping canal of the small intestine. Traditional technology for intestinal canal examination and endoscopy cannot exhibit the intestinal wall and extra-luminal structure well. With the development and advancement of multi-slice spiral computed tomography and magnetic resonance imaging (MRI), computed tomography enteroclysis (CTE) and magnetic resonance enteroclysis (MRE) are widely used in the examination and diagnosis of small intestinal tumors. CTE and MRE, with three-dimensional imaging capabilities and excellent soft-tissue contrast, can analyze the abnormalities of peripheral intestinal structure as well as the tunica mucosa. In addition, these two technologies can clearly reveal the localization, appearance, degree of mesenteric infiltration and remote tumor metastasis, which increases our cognition of the imaging diagnosis for intestinal tumors. Here we review recent progress in imaging (CT and MRI) examination and diagnosis of small intestinal tumors.

Do radiologists agree on the quality of computed tomography enterography?

This study aimed to assess variation between radiologists evaluating the quality of multi-detector computed tomography enterography. For 40 consecutive examinations, three experienced radiologists independently rated the following quality variables: % length of adequately filled bowel, bowel lumen diameters, bowel wall delineation, superior mesenteric vein, and bowel wall enhancement, artefacts, and total quality. We calculated the mean difference between observers with standard deviation (SD) for continuous variables and % total agreement, exact Fleiss kappa, and P-values (McNemar's test) for categorical variables. Depending on bowel segment (duodenum distal to bulb, jejunum, ileum, terminal ileum), mean difference between observers ranged from two to 33 (SD from 11 to 32) for % length of adequately filled bowel judged subjectively, 0-2 (SD 0-3) mm for smallest bowel lumen diameter and 0-4 (SD 3-7) mm for largest bowel lumen diameter. Agreement on bowel wall delineation was 80%/kappa 0.50 in duodenum, 90%/kappa 0.57 in jejunum, 75%/kappa 0.14 in ileum and 88%/kappa 0.17 in terminal ileum, where ratings differed between observers (P < 0.04). Agreement was 65%/kappa 0.18 for bowel wall enhancement judged subjectively. For contrast enhancement measured in Hounsfield Units, mean difference between observers ranged from two to 11 (SD 12-15) in normal jejunum wall and zero to one (SD 4-5) in the superior mesenteric vein depending on observer pair. Agreement was 78%/kappa 0.12 for image artefacts. Rating of total examination quality (good/optimal versus poor/very poor) differed between observers (P < 0.01); agreement was 60%/kappa 0.41. Many subjective evaluations varied between observers. We believe that measurements of bowel lumen diameters and contrast enhancement may be preferable.

Melanoma of the small intestine

Intestinal melanomas can be primary tumours or metastases of cutaneous, ocular, or anal melanomas. Primary intestinal melanoma is extremely rare, whereas metastatic melanoma of the small bowel is common because of the tendency for cutaneous melanoma to metastasise to the gastrointestinal tract. Because distinguishing between primary and metastatic intestinal melanoma can be difficult, the main features of each are discussed, and the diagnostic images used to detect intestinal melanoma are assessed. Routine barium examinations and CT have limited sensitivity, but PET imaging can improve detection of melanoma metastases to the small bowel. Although various treatment strategies have been tried in patients with intestinal melanoma, surgical removal of intestinal metastases is the treatment of choice in patients with resectable tumours. No systemic therapy improves survival in patients with melanoma metastatic to the intestines; thus, the prognosis for these patients is poor. Patients with primary melanoma of the small intestine have a worse prognosis than do patients with metastases of cutaneous melanoma.

Small bowel adenocarcinoma

Small bowel cancers are rare, accounting for only about 6000 cases/year in the United States, approximately 25% of which are small bowel adenocarcinomas. Small bowel adenocarcinomas have traditionally been considered to be highly fatal due to their nonspecific presentation at the time of diagnosis, and to the lack of responsiveness to older chemotherapy regimens. However, that paradigm may be changing. Newer diagnostic techniques such as video capsule and double balloon enteroscopy may facilitate earlier diagnosis. In addition, modern chemotherapy regimens have produced improved response rates and survival rates, when compared to historical controls. Still, there remains great need for multi-institutional, cooperative group studies to define the optimal treatment of small bowel adenocarcinoma, both in the adjuvant and advanced/metastatic setting.

Differential diagnosis of small bowel ischemia

This article presents the differential diagnosis for small bowel ischemia. Clinical presentation of small bowel ischemia is variable, presenting with a myriad of specific or nonspecific clinical and laboratory findings. The imaging findings associated with small bowel ischemia are variable and combinations of findings may be necessary for definitive diagnosis. More specific imaging findings in patients with acute small intestine ischemia include bowel wall gas, mesenteric vessel occlusion, mesenteric venous gas, portal venous gas, or absence of bowel wall enhancement. Less specific imaging findings include small bowel wall thickening, mesenteric stranding, and mesenteric fluid. Further complicating the issue, several small intestinal disease processes may mimic ischemia both clinically and radiographically. These alternate diagnoses include infectious, inflammatory, and infiltrative processes.

Asymptomatic ileal adenocarcinoma in the setting of undiagnosed Crohn’s disease

A 53-year old previously healthy male underwent a screening colonoscopy for detection of a potential colorectal neoplasm. The terminal ileum was intubated and a mass was noted. Examination of the colon was normal. The biopsy of the ileal mass was consistent with an adenocarcinoma arising from the terminal ileum. His father who had never been previously ill from gastrointestinal disease died of natural causes, but was found to have Crohn’s disease postmortem. The patient underwent exploratory laparotomy and a right hemicolectomy with a 30 cm section of terminal ileum in continuity. Findings were consistent with ileal adenocarcinoma in the setting of Crohn’s disease. The patient made an uneventful recovery. The pathology was stage 1 adenocarcinoma. This is a unique case in that on a screening colonoscopy, a favorable ileal adenocarcinoma was discovered in the setting of asymptomatic, undiagnosed ileal Crohn’s disease in a patient whose father had Crohn’s disease diagnosed postmortem.

Cost-effectiveness and patient tolerance of low-attenuation oral contrast material: milk versus VoLumen

OBJECTIVE

The purpose of our study was to prospectively compare the cost, effectiveness, and patient tolerance of milk and VoLumen, a 0.1% barium suspension, in patients undergoing abdominal and pelvic CT with oral and i.v. contrast media.

SUBJECTS AND METHODS

Two hundred fifteen consecutive outpatients were randomly assigned to receive either whole milk (n = 115) or VoLumen (n = 100). Results were independently reviewed by two radiologists who were blinded to the oral contrast agent used. Degree of bowel distention was qualitatively scored on a 4-point scale, and bowel wall visibility was graded qualitatively on a yes-or-no basis. A questionnaire regarding oral contrast tolerability was provided to each patient. Cost comparison of the two agents was performed.

RESULTS

No statistically significant differences were seen between whole milk and VoLumen with respect to degree of bowel distention and mural visualization for all segments of bowel studied (p > 0.05 for both reviewers). Significantly more patients ranked milk as pleasant in taste compared with VoLumen (p < 0.0001). More patients preferred milk compared with VoLumen (p < 0.0001). Milk was better tolerated than VoLumen, with fewer abdominal side effects, including abdominal discomfort (p = 0.019), cramping (p = 0.019), nausea (p = 0.016), and diarrhea (p = 0.0002). The cost per patient for VoLumen is $18 compared with $1.48 for milk.

CONCLUSION

Whole milk is comparable to VoLumen with respect to bowel distention and bowel wall visualization and has a lower cost, better patient acceptance, and fewer adverse symptoms. Milk is a cost-effective alternative to VoLumen as a low-attenuation oral contrast agent.

Comparison of neutral oral contrast versus positive oral contrast medium in abdominal multidetector CT

To determine whether neutral contrast agents with water-equivalent intraluminal attenuation can improve delineation of the bowel wall and increase overall image quality for a non-selected patient population, a neutral oral contrast agent (3% mannitol) was administered to 100 patients referred for abdominal multidetector row computed tomography (MDCT). Their results were compared with those of 100 patients given a positive oral contrast agent. Qualitative and quantitative measurements were done on different levels of the gastrointestinal tract by three experienced readers. Patients given the neutral oral contrast agent showed significant better qualitative results for bowel distension (P < 0.001), homogeneity of the luminal content (P < 0.001), delineation of the bowel-wall to the lumen (P < 0.001) and to the mesentery (P < 0.001) and artifacts (P < 0.001), leading to a significant better overall image quality (P < 0.001) than patients receiving positive oral contrast medium. The quantitative measurements revealed significant better distension (P < 0.001) and wall to lumen delineation (P < 0.001) for the patients receiving neutral oral contrast medium. The present results show that the neutral oral contrast agent (mannitol) produced better distension, better homogeneity and better delineation of the bowel wall leading to a higher overall image quality than the positive oral contrast medium in a non-selected patient population.

Primary small intestinal malignant tumors: survival analysis of 48 postoperative patients

BACKGROUND

Primary small intestinal malignant tumor is relatively uncommon compared to gastric and colorectal cancer. It is difficult to make an early diagnosis due to the atypical primary symptoms and lack of effective diagnostic methods.

GOALS

To analyze the relationship between the prognoses, histologic type, and therapeutic strategy in postoperative patients with small intestinal tumor.

STUDY

The parameters that affect survival were evaluated using multivariate Cox analysis in 48 cases of small intestinal tumor (confirmed by operation and pathology) for the past 10 years.

RESULTS

The overall survival (OS) of all 48 cases after surgery was 28 months. The 5-year postoperative survival rate for all of the 48 cases was 27.1%. The median OS for all the 20 stage II/III patients who received adjuvant chemotherapy was 28 months, whereas the median OS for the 15 patients who did not receive the therapy was 37 months (P=0.276). The median time to progression for 8 patients with adenocarcinoma who received 5-fluorouracil or platinum-based palliative chemotherapy was 7 months, whereas for the patients who did not receive the therapy it was 3 months (P=0.06). The result of multivariate analyses showed that only the clinical stage was significantly correlated with OS (P<0.001).

CONCLUSIONS

The prognosis for small intestinal malignancies is associated with clinical stage, and palliative chemotherapy with a 5-fluorouracil or platinum-based regimen offers a potential benefit to patients with adenocarcinoma. Postoperative adjuvant chemotherapy seems to hold no therapeutic or survival benefit for patients with primary small bowel malignancies.