MDCT for suspected appendicitis: effect of reconstruction section thickness on diagnostic accuracy, rate of appendiceal visualization, and reader confidence using axial images.

OBJECTIVE: The purpose of this study was to evaluate interpretative performance with different MDCT reconstruction parameters in adult patients with suspected appendicitis. MATERIALS AND METHODS: MDCT scans of 212 adult patients obtained in an emergency department with a 64-MDCT scanner were prospectively collected. Acquisition technique included 24 x 1.2 mm detector configuration and IV contrast administration with or without oral contrast administration. Data sets were reconstructed with three techniques: 5 x 5 mm, 3 x 3 mm, and 2 x 1 mm (section thickness x interval). Each of the 212 sets of images (grouped by reconstruction technique) was reviewed retrospectively using axial sections by two independent readers blinded to diagnosis. Medical record review was conducted to identify patients with appendicitis. Visualization of the appendix, confidence in visualization, confidence for presence or absence of specific CT findings, diagnostic accuracy, and diagnostic confidence were compared across reconstruction techniques. Data were analyzed with simple and ordinal logistic regression with adjustment for multiple observations derived from each patient and for reader differences. RESULTS: Progressively thinner reconstruction section thickness was associated with a significant increase in the rate of visualization of the appendix (p < 0.001 for 5 x 5 vs 3 x 3; p = 0.03 for 3 x 3 vs 2 x 1), visualization confidence (p < 0.001 for 5 x 5 vs 3 x 3 and 3 x 3 vs 2 x 1), and confidence for presence or absence of findings. Seventeen subjects (8%) had appendicitis. Correctness of diagnosis was not significantly associated with reconstruction method. However, for correctly diagnosed cases interpreted as normal, impression confidence increased with progressively thinner section thickness (p < 0.001 for 5 x 5 vs 3 x 3 and 3 x 3 vs 2 x 1). CONCLUSION: In this investigation of contrast-enhanced MDCT of the appendix, visual ization of the appendix and confidence in interpretation of axial images progressively improved with use of thinner reconstruction sections.

Thoracic aortic stent-grafts: utility of multidetector CT for pre- and postprocedure evaluation.

Indications for and experience with placement of endovascular stent-grafts in the thoracic aorta are still evolving. Common pathologic conditions of the thoracic aorta that are amenable to stent placement include penetrating ulcers, aortic dissection, aortic aneurysms, aortic rupture, and congenital abnormalities. Advances in multidetector computed tomography (CT) permit high-quality two-dimensional multiplanar reformation and three-dimensional rendering, which are essential for comprehensive assessment of the thoracic aorta. The ability of multidetector CT to allow detailed evaluation in any plane or perspective enables detection of thoracic aortic disease and assessment of its relationship to normal vessels. Potential complications of endovascular stent placement include endoleaks, stent migration, pseudoaneurysms, dissection, aortic perforation, kinking, thrombosis, and coverage of vital branch vessels. It is important for the radiologist to not only detect pathologic conditions of the thoracic aorta but also to provide the referring clinician with the necessary pre- and postprocedure information to determine appropriate clinical care.

Three-dimensional computed tomographic imaging of complex congenital cardiovascular abnormalities.

Primary evaluation of congenital cardiac abnormalities traditionally relies upon echocardiography and conventional angiography, both of which have potential limitations. Echocardiography is an operator dependant study, limited by a small window and patient movement. Conventional angiography is an invasive procedure with an inherent risk of catheter complication such as vessel damage, bleeding, stroke and infection. During angiography, overlapping of the pulmonary and systemic circulation often provides a confusing picture given complex anatomy. Another limiting factor of particular significance in young children is radiation dose and contrast administration during catherization procedures. Three-dimensional MDCT provides an alternative to alleviate these pitfalls of traditional cardiac diagnostic studies. Development of multi-detector computed tomography (MDCT) and 3D software provides new methods for non-invasive visualization and evaluation of congenital cardiac abnormalities. The multiplanar, volumetric functions allow faster and more complete computed tomography diagnosis and better understanding of clinical relevance of complex cardiac anatomy. In addition, 3D imaging is particularly useful for preoperative planning and postoperative outcomes. This essay provides case studies to illustrate the usefulness of MDCT/3D CT for evaluation of complex congenital heart disease.

Focal FDG uptake in a pancreatic lipoma mimicking malignancy.

Positron emission tomography (PET) using the glucose analog 18-F-fluoro-2-deoxy-D-glucose (FDG) is commonly obtained to stage patients with cancer. Benign lesions can be a source of false-positive PET examinations, leading to incorrect staging and treatment of tumors. Computed tomography can aid in distinguishing between certain benign and malignant lesions. The authors report a case of a pancreatic lipoma producing a false-positive PET examination.

Concurrent focal hepatic and splenic lesions: a pictorial guide to differential diagnosis.

Although medical literature and differential diagnoses discussions tend to be organ specific, systemic diseases more commonly manifest with multi-organ involvement. Detection of dual organ involvement combined with clinical history narrows the differential to provide a more specific diagnosis. Two organs closely linked are the liver and the spleen. Many processes affect both of these organs through their common denominator, the reticuloendothelial system (RES). This pictorial essay reviews the wide spectrum of benign and malignant pathologies to be considered when computed tomography (CT) demonstrates concurrent focal disease in the liver and spleen.