The Question: What is the diagnosis on the CT image below?
The answer to the image quiz of 2/29/12 is bilateral renal infarction.
The Question What does the non-contrast CT image demonstrate? What could be the possible cause?
Explanation
This is a case of simultaneous thromboembolism of both the mesenteric and renal arteries.
1. Arterial atheroembolism has an incidence of about 10% in the visceral vessels, 20% in the cerebrovascular circulation and 70% in the peripheral circulation.
2. Visceral emboli preferentially lodge in the superior mesenteric artery (SMA) due to its oblique origin from the abdominal aorta.
3. Thrombo-embolism of the renal arteries is rare.
4. The most important source of spontaneous arterial macroemboli is the heart. Two thirds to three fourths of these are due to dysarrythmia and 20% are secondary to myocardial infarction.
5. Left ventricular (LV) mural thrombus is a well-recognized complication of acute myocardial infarction. The pathophysiology involves a combination of dyskinesis and freshly infarcted inflamed myocardium containing abundant fibrin. This serves as a nidus for platelet aggravation and activation of the coagulation cascade. The resultant thrombus is composed of fibrin, red blood cells and platelets.
6. The overall incidence of a mural thrombus at post-mortem in patients dying from myocardial infarction is reported to be 30-40%. In the patients who survive myocardial infarction, the incidence of LV mural thrombus depends on the size, site and the imaging modality used to detect it. Large anterior Q-wave infarction has higher incidence of mural thrombus as compared to inferior Q-wave and non-Q-wave infarctions.
7. The transthoracic 2-D echocardiography is the most common imaging modality used to detect a mural thrombus. It has a reported sensitivity of 95% and specificity of 86%.
8. 50% of all mural thrombi are visible 48 hours after a myocardial infarction and 90% within the first week. Rarely, the thrombus may appear one month after the infarction.
(Source: D. Joshi, N.et al, published previously in The Internet Journal of Surgery. 2007 Volume 11 Number 1)
