MDCT of the abdomen

Water as a Contrast Medium: A Re-evaluation Using the Multidetector-row Computed Tomography

Water as an intraluminal negative contrast medium produces improved image quality with reduced artefact. However, rapid absorption of oral water in the bowel relative to speed and timing of image capturing has limited its clinical application. These findings predate advances in multidetector-row computed tomography (CT). To re-evaluate differences in image quality, we studied image clarity and luminal distention between the same group of patients who received both a pancreas protocol CT (PPCT) that uses oral water and a conventional positive oral contrast scan. We reviewed 66 patients who had previously undergone both a PPCT and an oral contrast abdominal CT. CT images were independently reviewed by two board-certified radiologists who scored degree of hollow viscus distention and visualization of mural detail using a Likert 5-point scale. Results were evaluated by using the Wilcoxon-signed rank test. Student's t test was applied to evaluate the differences in radiation dosage and Spearman's correlational test was used to evaluate interrater correlation between the radiologists. In comparing the mean radiation dosage, there was no statistical difference between the two protocols, and there was good interrater association with ratios of 0.595 and 0.51 achieved for the PPCT and conventional oral scan, respectively. The Wilcoxon signed-rank test showed statistical differences in the stomach ( P < 0.001) for both clarity ( P < 0.001) and distention ( P < 0.001), the duodenum for both clarity ( P < 0.001) and distention ( P = 0.02), and the ileum for distention ( P = 0.02) with the PPCT having a better median score for organ clarity in the stomach and duodenum and better luminal distention in the stomach, equal distention in the duodenum, and slightly worse distention in the ileum. For the remainder of the bowel and organs evaluated, there was no statistically significant difference in the ratings between the two protocols. Using present CT scan technology, water can be an effective contrast medium causing better or equal distention in the bowel and better or equal clarity than routine barium contrast. This calls for a need to reconsider the use of water as a contrast medium in clinical practice.

Acute colonic diverticulitis: an update on clinical classification and management with MDCT correlation

Currently, the most commonly used classification of acute colonic diverticulitis (ACD) is the modified Hinchey classification, which corresponds to a slightly more complex classification by comparison with the original description. This modified classification allows to categorize patients with ACD into four major categories (I, II, III, IV) and two additional subcategories (Ia and Ib), depending on the severity of the disease. Several studies have clearly demonstrated the impact of this classification for determining the best therapeutic approach and predicting perioperative complications for patients who need surgery. This review provides an update on the classification of ACD along with a special emphasis on the corresponding MDCT features of the different categories and subcategories. This modified Hinchey classification should be known by emergency physicians, radiologists, and surgeons in order to improve patient care and management because each category has a specific therapeutic approach.

Defining the optimal cut-off values for liver enzymes in diagnosing blunt liver injury

BACKGROUND

Patients with blunt trauma to the liver have elevated levels of liver enzymes within a short time post injury, potentially useful in screening patients for computed tomography (CT). This study was performed to define the optimal cut-off values for serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in patients with blunt liver injury diagnosed with contrast enhanced multi detector-row CT (CE-MDCT).

METHODS

All patients admitted from May 2006 to July 2013 to Teikyo University Hospital Trauma and Critical Care Center, and who underwent abdominal CE-MDCT within 3 h after blunt trauma, were retrospectively enrolled. Using receiver operating characteristic (ROC) curve analysis, the optimal cut-off values for AST and ALT were defined, and sensitivity and specificity were calculated.

RESULTS

Of a total of 676 blunt trauma patients 64 patients were diagnosed with liver injury (Group LI+) and 612 patients without liver injury (Group LI-). Group LI+ and LI- were comparable for age, Revised Trauma Score, and Probability of survival. The groups differed in Injury Severity Score [median 21 (interquartile range 9-33) vs. 17 (9-26) (p < 0.01)]. Group LI+ had higher AST than LI- [276 (48-503) vs. 44 (16-73); p < 0.001] and higher ALT [240 (92-388) vs. 32 (16-49); p < 0.001]. Using ROC curve analysis, the optimal cut-off values for AST and ALT were set at 109 U/l and 97 U/l, respectively. Based on these values, AST ≥ 109 U/l had a sensitivity of 81%, a specificity of 82%, a positive predictive value of 32%, and a negative predictive value of 98%. The corresponding values for ALT ≥ 97 U/l were 78, 88, 41 and 98%, respectively, and for the combination of AST ≥ 109 U/l and/or ALT ≥ 97 U/l were 84, 81, 32, 98%, respectively.

CONCLUSIONS

We have identified AST ≥ 109 U/l and ALT ≥ 97 U/l as optimal cut-off values in predicting the presence of liver injury, potentially useful as a screening tool for CT scan in patients otherwise eligible for observation only or as a transfer criterion to a facility with CT scan capability.

Diagnosis of bowel diseases: The role of imaging and ultrasonography

Examinations with a visualisation of the anatomy and pathology of the gastrointestinal (GI) tract are often necessary for the diagnosis of GI diseases. Traditional radiology played a crucial role for many years. Endoscopy, despite some limitations, remains the main technique in the differential diagnosis and treatment of GI diseases. In the last decades, the introduction of, and advances in, non-invasive cross-sectional imaging modalities, including ultrasound (US), computed tomography (CT), positron-emission tomography (PET), and magnetic resonance imaging, as well as improvements in the resolution of imaging data, the acquisition of 3D images, and the introduction of contrast-enhancement, have modified the approach to the examination of the GI tract. Moreover, additional co-registration techniques, such as PET-CT and PET-MRI, allow multimodal data acquisition with better sensitivity and specificity in the study of tissue pathology. US has had a growing role in the development and application of the techniques for diagnosis and management of GI diseases because it is inexpensive, non-invasive, and more comfortable for the patient, and it has sufficient diagnostic accuracy to provide the clinician with image data of high temporal and spatial resolution. Moreover, Doppler and contrast-enhanced ultrasound (CEUS) add important information about blood flow. This article provides a general review of the current literature regarding imaging modalities used for the evaluation of bowel diseases, highlighting the role of US and recent developments in CEUS.

The accuracy of 64-slice MDCT for determining the perforation site of the gastrointestinal tract: ROC analysis

PURPOSE

This study was performed to evaluate the diagnostic performance of 64-slice multidetector-row computed tomography (MDCT) for preoperatively detecting the perforation site in patients with gastrointestinal (GI) tract perforations.

MATERIALS AND METHODS

A total of 49 patients with pathologically proven GI tract perforations, who had undergone MDCT were included in this study. The contrast-enhanced axial images (3 mm thick) and multiplanar reformation (MPR) images (3 mm thick) were generated for all the patients. Two radiologists independently reviewed the two sets of MDCT images (axial set: the axial images alone, and combined set: the axial and MPR images) for the detection of the perforation site. The perforation site was considered to be positive according to the direct and indirect findings. The diagnostic accuracy was assessed with a receiver operating characteristic (ROC) analysis. Weighted kappa statistics were used to evaluate the interobserver agreement.

RESULTS

The corresponding values in respect of the first and the second observers for the areas under the ROC curve were 0.984 and 0.966 for the axial set; and 0.998 and 0.973 for the combined set. The differences were not statistically significant between the two data sets for each observer (P > 0.05). Both the observers detected the perforation site in 43 (87.8%) and 40 (81.6%) patients on the axial set, and in 46 (93.9%) and 41 (83.7%) patients on the combined set, respectively. The kappa values between the two observers showed excellent agreement with the two data sets.

CONCLUSION

64-slice MDCT showed a consistently excellent diagnostic performance for preoperatively determining the perforation site in patients with GI tract perforations, irrespective of the availability of the MPR images.

Multidetector-row computed tomography findings of sclerosing mesenteritis with associated diseases and its prevalence

PURPOSE

Our aim was to report the multidetector-row computed tomography (MDCT) findings of sclerosing mesenteritis, which is a rare disease characterized by chronic nonspecific inflammation of mesenteric adipose tissue. It has associated diseases, and we explored its prevalence.

MATERIALS AND METHODS

A total of 2100 patients were evaluated retrospectively for sclerosing mesenteritis between December 2007 and May 2009. Signs and symptoms, associated diseases, laboratory data, surgical histories, and related findings of a misty mesentery, which corresponds to sclerosing mesenteritis on MDCT, were recorded.

RESULTS

Misty mesentery findings were seen in 51 (2.43%; 35 men) patients. Their ages ranged between 33 and 78 years (mean 56.2 years). The most frequent complaint of patients was abdominal pain (n = 19; 37.2%). The most prominent possible causative and/or associated factors in our study were malignancy (n = 9; 17.6%), previous surgery (n = 17; 33.3%), smoking (n = 20; 39.2%), coronary artery disease (n = 9; 17.6%), urolithiasis (n = 10; 19.6%), hypertension (n = 18; 35.2%), hyperlipidemia (n = 13; 25.5%), and diabetes mellitus (n = 11; 21.5%). On MDCT, density values in mesenteric fat (-62.8 ± 18.6 HU) were significantly higher than the values for subcutaneous (-103.9 ± 5.8 HU) and retroperitoneal (-105 ± 6 HU) fatty tissues (both P < 0.0001). A partially hyperdense stripe (n = 37; 72.6%), well-defined soft tissue nodules (100%), hypodense fatty halo enclosing vessels (n = 1; 1.9%), and nodules (n = 12; 23.5%) were demonstrated in most of the patients.

CONCLUSION

The diagnosis of sclerosing mesenteritis has increased with the more frequent use of MDCT and the popularization of the DICOM viewer. Defined hallmarks on MDCT can be helpful for differentiating sclerosing mesenteritis from other pathologies.

A typical presentation of a rare cause of obscure gastrointestinal bleeding

A 52-year-old white woman had suffered from intermittent gastrointestinal (GI) bleeding for one year. Upper GI endoscopy, colonoscopy and peroral double-balloon enteroscopy (DBE) did not detect any bleeding source, suggesting obscure GI bleeding. However, in videocapsule endoscopy a jejunal ulceration without bleeding signs was suspected and this was endoscopically confirmed by another peroral DBE. After transfusion of packed red blood cells, the patient was discharged from our hospital in good general condition. Two weeks later she was readmitted because of another episode of acute bleeding. Multi-detector row computed tomography with 3D reconstruction was performed revealing a jejunal tumor causing lower gastrointestinal bleeding. The patient underwent exploratory laparotomy with partial jejunal resection and end-to-end jejunostomy for reconstruction. Histological examination of the specimen confirmed the diagnosis of a low risk gastrointestinal stromal tumor (GIST). Nine days after surgery the patient was discharged in good health. No signs of gastrointestinal rebleeding occurred in a follow-up of eight months. We herein describe the complex presentation and course of this patient with GIST and also review the current approach to treatment.

Spiral head CT in the evaluation of acute intracranial pathology: a pictorial essay

The purpose of this pictorial essay is to review the benefits of spiral head computed tomography (CT) with routine multiplanar reformations in the evaluation of acute intracranial pathology. This technique is particularly useful in trauma patients for detection of skull base or calvarial fractures, thin tentorial subdural hematomas, or for more specific characterization of intracranial hemorrhage. The benefits of multiplanar reformations have been described for a variety of other diagnoses in the chest, abdomen, extremities, and spine, and their routine use continues to grow with the widespread availability of multi-slice CT scanners. In this article, we describe spiral head CT technique with multiplanar reformations as an alternative to the routinely used sequential technique. Subtle findings and lesions aligned predominantly in the axial plane can often be visualized to better advantage with multiplanar reformations. We also address technical factors for optimizing spiral technique.

Prevalence of extravascular collateral findings during 64-slice CT angiography of the abdominal aorta and lower limbs

PURPOSE

The aim of this study was to assess the prevalence of extravascular collateral findings during 64-slice CT angiography of the abdominal aorta (AA-CTA) and lower limbs (LL-CTA).

MATERIALS AND METHODS

The images of 536 AA-CTA and LL-CTA examinations performed for suspected aortic and peripheral vascular disease in 500 patients were retrospectively reviewed. Two radiologists evaluated the 5-mm axial images independently using appropriate window settings for the area under investigation. Collateral findings were divided according to their clinical significance into significant, nonsignificant and meriting further investigation.

RESULTS

No collateral findings were identified in 97/500 patients (19.4%). In the remaining patients, 821 collateral findings were detected, of which 43 (5.24%) were classified as significant, 135 (16.44%) as meriting further investigation and 643 (78.32%) as nonsignificant. The findings indicative of the presence of a malignant lesion totalled 36 (4.5%).

CONCLUSIONS

AA-CTA and LL-CTA demonstrate a nonnegligible prevalence of collateral findings, many of them major. It therefore appears that the evaluation should focus not only on the image reconstructions to identify vascular disease, but also on the native axial images to detect incidental findings.

Imaging of the gastrointestinal tract-novel technologies

Imaging of the gastrointestinal tract is very useful for research and clinical studies of patients with symptoms arising from the gastrointestinal tract and in visualising anatomy and pathology. Traditional radiological techniques played a leading role in such studies for a long time. However, advances in non-invasive modalities including ultrasound (US), computed tomography (CT), positron emission tomography (PET), magnetic resonance imaging (MRI), etc, have in the last decades revolutionised the way in which the gastrointestinal tract is studied. The resolution of imaging data is constantly being improved and 3D acquisition, tools for filtering, enhancement, segmentation and tissue classification are continually being developed. Additional co-registration techniques allow multimodal data acquisition with improved classification of tissue pathology. Furthermore, new functional imaging techniques have become available. Altogether, the future of gastrointestinal imaging looks very promising which will be of great benefit in clinical and research studies of gastrointestinal diseases. The purpose of this review is to highlight the capabilities of the newest techniques to explore the detailed morphology, biomechanical properties, function and pathology of the gastrointestinal tract.

Acute inflammatory bowel disease of the small intestine in adult: MDCT findings and criteria for differential diagnosis

Inflammatory changes of the intestine leading to acute abdomen could represent a frequent diagnostic challenge for radiologists actively involved in the emergency area. MDCT imaging findings needs to be evaluated considering the clinical history and symptoms and other abdominal findings that could be of help in differential diagnosis. Several protocols have been suggested and indicated in the imaging of patient with acute intestine. However, a CT protocol in which the precontrast scanning of the abdomen is followed by i.v. administration of contrast medium using the 45-55 s delay could be effective for an optimal visualization of the bowel wall. It is important to learn to recognize how the intestine reacts to the injury and how it "talks", in order to become aware of the different patterns of disease manifestation related to an acute intestinal condition, for an effective diagnosis of active and acute inflammatory bowel disease.