Biomedical subjects
Publications and source records attributed to Man Hon.
A rare source of potentially massive lower gastrointestinal hemorrhage in women is advanced gynecologic malignancy. Such patients can develop gastrointestinal hemorrhage with or without prior pelvic irradiation, due to arteriocolic fistulas. Angiography permits the correct diagnosis and subsequent embolotherapy.
Accurate diagnosis of deep venous thrombosis (DVT) is very difficult, and imaging plays a crucial role in the diagnosis or exclusion of DVT. The initial test of choice for diagnosis of acute thigh as well as upper extremity DVT is ultrasound, because of its high accuracy, relatively low cost, portability, and lack of ionizing radiation. In patients who are undergoing CT pulmonary angiography for suspected pulmonary embolism, CT venography can be performed as part of the examination, for comprehensive evaluation of the venous system in the legs, abdomen, and pelvis. MR has a problem-solving role, and conventional venography is now limited to specific scenarios including evaluation of central DVT in the upper extremities, as a prelude to intervention for thrombolysis/thrombectomy, and prior to placement of an inferior vena cava filter. This article discusses the imaging findings of DVT, and the role of these imaging examinations in the evaluation of patients with suspected DVT.
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This article reviews the research to date, as well as our clinical experience from two institutions, on gadolinium-enhanced computed tomographic angiography (gCTA) for imaging the body. gCTA may be an appropriate examination for the small percentage of patients who would benefit from noninvasive vascular imaging, but who have contraindications to both iodinated contrast and magnetic resonance imaging. gCTA is more expensive than CTA with iodinated contrast, due to the dose of gadolinium administered, and gCTA has limitations compared with CTA with iodinated contrast, in that parenchymal organs are not optimally enhanced at doses of 0.5 mmol/kg or lower. However, in our experience, gCTA has been a very useful problem-solving examination in carefully selected patients. With the advent of 16-64 detector CT, in combination with bolus tracking, we believe that the overall dose of gadolinium needed for diagnostic CTA examinations, while relatively high, can be safely administered.