Browsing by Author "Brito, JB"
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- Gastroenterologic and Radiologic Approach to Obscure Gastrointestinal Bleeding: How, Why, and When?Publication . Graça, B; Freire, PA; Brito, JB; Ilharco, J; Carvalheiro, VM; Caseiro-Alves, FGastrointestinal (GI) bleeding is a common clinical condition that is increasingly seen in an aging population and frequently requires hospitalization and intervention, with significant morbidity and mortality. Obscure GI bleeding (OGIB) is defined as loss of blood with no source identified after upper endoscopy and colonoscopy. Whether an obscure site of bleeding is clinically evident or silent, it constitutes a diagnostic and therapeutic challenge for the clinician. Gastroenterology and radiology provide the essential diagnostic tools used to evaluate suspected OGIB, each with its strengths and weaknesses. Small bowel series and conventional enteroclysis have a limited role in OGIB. Computed tomographic (CT) enterography and CT enteroclysis are noninvasive techniques with promising results in evaluation of small bowel disease and silent OGIB. CT angiography is a useful triaging tool for diagnosing or excluding active GI hemorrhage, localizing the site of bleeding, and guiding subsequent treatment. Tagged red blood cell scanning is the most sensitive technique for detection of active GI bleeding and allows imaging over a prolonged period, making it useful for detecting intermittent bleeding. Capsule endoscopy has emerged as an important tool for investigating OGIB, but it may soon have competition from double-balloon enteroscopy, a diagnostic technique that can also facilitate therapy.
- The hypointense liver lesion on T2-weighted MR images and what it meansPublication . Curvo-Semedo, L; Brito, JB; Seco, MF; Costa, JM; Marques, CB; Caseiro-Alves, FThe vast majority of focal liver lesions are hyperintense on T2-weighted magnetic resonance (MR) images. Rarely, however, hepatic nodules may appear totally or partially hypointense on those images. Causes for this uncommon appearance include deposition of iron, calcium, or copper and are related to the presence of blood degradation products, macromolecules, coagulative necrosis, and other conditions. Although rare, low signal intensity relative to surrounding liver on T2-weighted images may be seen in a wide spectrum of lesions. Examples include cases of focal nodular hyperplasia, hepatocellular adenoma, hepatocellular carcinoma, metastases, leiomyoma, siderotic or dysplastic nodules, nodules in Wilson disease, granuloma, and hydatid cyst. On fat-suppressed T2-weighted images, nodules with a lipomatous component, such as lipoma, angiomyolipoma, hepatocellular adenoma, and hepatocellular carcinoma may also appear partially or totally hypointense. The conjunction of other MR imaging findings and their integration in the clinical setting may allow a correct diagnosis in a considerable proportion of cases. The cause for T2-weighted hypointensity may not be, however, always recognized, and only pathologic correlation may provide the answer. The aims of this work are to discuss the causes and mechanisms of hypointensity of liver lesions on T2-weighted images and proposing an algorithm for classification that may be useful as a quick reminder for the interested reader.