Medical Radiology - Lazar A.P. 2008

Radiation Examination of the Heart and Blood Vessels
Vascular Diseases

Most commonly among large vessels, the aorta is affected, and less frequently the SUPERIOR VENA CAVA and pulmonary trunk.

Atherosclerosis involves lipid deposition in the vessel wall, The formation of atheromatous plaques, and Connective Tissue proliferation accompanied by calcium salt deposits. Radiologically, sclerotic vascular changes are characterized by widening of the vessel lumen, elongation and tortuosity of its course, and a more intense shadow of the sclerosed vessel. Angiographically, irregular contours and filling defects caused by atheromatous plaques are revealed.

Aortic atherosclerosis mostly begins after the age of 40, predominantly affecting the abdominal portion, and less frequently the aortic arch and thoracic section. The radiological signs of aortic atherosclerosis in the anteroposterior projection include a high position of the upper arch margin (reaching the clavicle level) and a significant Displacement of the aorta to the left of the spinal margin. Not infrequently, the Thoracic Aorta displaces the Trachea and Esophagus to the right. In this case, an impression is formed on the left wall of the esophagus. In the left anterior oblique projection, an increase in the diameter of the aortic shadow up to 5-6 cm and widening of the aortic window are observed, and bands of calcification along the edge of the aortic shadow are often visible.

Sclerosis of the superior vena cava is likewise accompanied by an increase in its length and width. Upon radiological examination in the anteroposterior projection, an intense shadow with a convex lateral margin is defined along the right border of the cardiovascular shadow. The shadow of the superior vena cava extends upward to the lung apex and crosses the clavicle.

Atherosclerosis of the aorta, the superior vena cava, and smaller vessels, manifested as wall calcifications, is best detected using computed tomography.

An aneurysm is defined as a local dilatation of a Blood vessel. Aortic aneurysms are classified into: 1) true aneurysms, when all three layers of the arterial wall bulge; 2) false aneurysms, when the intima and media rupture and only the adventitia bulges; 3) dissecting aneurysms, when a space is formed between the layers of the arterial wall. Dissecting aneurysms are the most difficult to diagnose; they are characterized by an unfavorable prognosis due to the potential rupture of an intramural hematoma. According to the shape of the dilatations, cylindrical, fusiform, and saccular aneurysms are distinguished (Fig. 157).

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Fig. 157. Saccular Aneurysm of the anterior cerebral artery on a digital subtraction angiogram.

Fig. 158. Aortic aneurysm on a radiograph (diagram).

A - of the aortic arch above the isthmus; B - of the descending part of the aorta below the isthmus.

The majority of aneurysms are caused by atherosclerosis or trauma. Atherosclerotic aortic aneurysms predominantly occur in the descending portion, whereas traumatic ones are localized in the arch region. Radiologically, an additional shadow is revealed that abuts the aorta with a broad base and has clear, smooth contours (Fig. 158). In the thoracic region, displacement of the trachea and the contrast-filled esophagus to the right may be observed, while in the abdominal region, erosion (cupping) of vertebral bodies can occur. CT, aortography, and ultrasound assist in determining the localization, size, and shape of the aneurysm (Fig. 159). Thrombi within an aneurysm are detected on computed tomograms due to a lower densitometric density (+20-+30 HU) compared to blood density.

Obliterating endarteritis involves the narrowing primarily of peripheral vessels. Most researchers recognize an autoimmune genesis for the disease. It occurs more frequently in young men who smoke heavily. Prolonged arterial spasm caused by the effects of nicotine leads to chronic ischemia of the arterial wall, resulting in intimal hyperplasia, adventitial fibrosis, and degenerative Changes in the nervous apparatus of the vascular wall. These morphological changes create conditions for thrombus formation and obliteration of the arterial lumen. The Tissues of the peripheral PARTS OF THE extremities suffer the most from the disease. The Nature and extent of vascular lesions in obliterating endarteritis are best revealed by arteriography (Fig. 160).

Fig. 159. Atherosclerosis and aneurysm of the descending part of the aorta (arrow) on a computed tomogram:

A - in the horizontal plane;

B - multiplanar reconstruction in the sagittal plane.

Fig. 160. Obliterating endarteritis of the right common iliac artery on an arteriogram.

Narrowing (stenosis) of the cerebral Arteries can cause an infarction (or ischemic stroke) in a specific area of the Brain. The arterial and venous Vessels of the brain can be examined non-invasively using brain MRI in angiographic mode (Fig. 161).

Fig. 161. Stenosis of the right middle and left posterior cerebral arteries on brain MRI in angiographic mode.