X-ray signs of tumors of the skull and brain

Clinical diagnosis of brain tumors involves great difficulties. Depending on the location and nature of growth, the tumor can cause both cerebral symptoms (headache, dizziness, impaired consciousness, personality change, etc.) and focal neurological disorders (visual, hearing, speech, motor impairment, etc.) . Moreover, the same tumor in different periods of development is completely "silent", it causes severe disorders right up to loss of consciousness.

Currently, doctors have a set of radiation methods that provide detection of a brain tumor in almost 100% of cases. The recognized leaders among the radiation methods of diagnosis are CT and MRI. The main tasks facing a specialist in the field of radiation diagnosis in the examination of patients with brain tumors:

1. to reveal a tumor;
2. determine its topography;
3. establish its macrostructure (solid or cystic character, the presence of necrosis or calcification);
4. to determine the relationship of the tumor with the surrounding brain structures (the presence of hydrocephalus, mass effect).

On computer and magnetic resonance tomograms there are direct and indirect signs of a tumor. Direct indication is the direct image of the tumor itself. Tumor imaging on magnetic resonance tomograms is associated with different proton density and magnetic relaxation time of normal and tumor tissue. On computer tomograms, the image arises from the fact that the tumor tissue differs from the surrounding brain substance from the absorption coefficient of X-ray radiation. With a small absorption of X-ray radiation, the tumor emerges as a region of reduced density (hypodense region). According to its shape, size and outlines, it is possible to judge to a certain extent the magnitude and nature of the growth of the neoplasm. We only note that there may be a hypodense zone around the edema around it, somewhat "concealing" the true dimensions of the tumor. Some resemblance to the tumor has a brain cyst, especially when it is irregularly configured, but the content of the cyst by the amount of absorbed X-ray radiation is close to water.

Tumors emanating from the arachnoid membrane - arachnoidendothelioma (meningioma) often have a fairly high density and are distinguished on the tomograms as rounded hyperdense formations. Most of these tumors are well supplied with blood, so after the introduction of the radiopaque substance their density on the tomograms increases. A direct image of the tumor can be obtained by radionuclide study. A number of RFPs, for example 99mTc-pertechnetate, accumulate in an increased quantity in the neoplasm due to a violation of the blood-brain barrier. On scintigrams and especially on emission tomograms the site of the increased concentration of the radionuclide is determined - the "hot" focus.

Indirect signs of a brain tumor include:

1. mixing of the surrounding parts of the brain, including the structures of the midline;
2. ventricular deformation and disturbances of the liquor circulation, up to the development of occlusive hydrocephalus;
3. different in extent and severity of the phenomenon of cerebral edema;
4. lime deposits in the tumor;
5. destructive and reactive changes in the adjacent bones of the skull.

The role of angiography in the diagnosis of brain tumors is low. Its main purpose is to determine the nature of vascularization, if surgical treatment is planned, or preoperative embolization. Naturally, they always prefer to perform DSA.

Tumors of the skull bones are diagnosed by conventional radiographs and tomograms. The osteoma is most visible, as it consists of bone tissue and excels in pictures. In most cases, the osteoma is localized in the region of the frontal sinus. The hemangioma picture is quite indicative. It determines the rounded defect of bone tissue with finely grooved compressed edges. Sometimes, against the background of such a defect, one can notice radially divergent finest bone rafters or cellular structures.

However, it is especially common for specialists in the field of radiation diagnostics to encounter single or multiple destructive foci in the bones of the skull, which have a round or irregular shape. The number of foci varies from one to several tens. Their magnitude varies widely. The contours of the destructive foci are smooth, but they are not clear, there are no sequestration in them. Such foci are either metastasis of a malignant tumor originating from a tumor of the lung, breast, stomach, kidney, etc., or the manifestation of myeloma. According to radiographs, it is almost impossible to distinguish myeloma nodes and metastasis of cancer. Differential diagnosis is based on the results of plasma protein electrophoresis and urinalysis. Detection of the paraprotein testifies to myeloma. In addition, scintigraphy in patients with metastases reveals hyperfaxation of RFP in sites of bone tissue destruction, whereas in myeloma such hyperfixation is usually absent.

Tumors in the field of the Turkish saddle occupy a special place in clinical oncology. The reasons for this are manifold. First, the anatomical factors matter. In the Turkish saddle there is such an important endocrine organ as the pituitary gland. To the saddle there are carotid arteries, venous sinuses, and behind - the basilar venous plexus. Above the Turkish saddle, at a distance of about 0.5 cm, there is a cross between the optic nerves, therefore, if the area is affected, visual disturbances often occur. Secondly, with tumors of the pituitary gland, hormonal status is violated, since many kinds of adenomas of the pituitary gland are able to produce and release into the blood strong substances that cause endocrine syndromes.

Of the pituitary tumors, the most common is the chromophobic adenoma growing from the chromophobic cells of the anterior lobe of the gland. Clinically, it manifests itself in the syndrome of adiposogenital dystrophy (obesity, weakening of sexual function, reduction of basal metabolism). The second most frequent tumor is eosinophilic adenoma, which also develops from the cells of the anterior lobe of the pituitary gland, but causes a completely different syndrome - acromegaly. For this disease, in addition to a number of common symptoms, the growth of bones is characteristic. In particular, the radiographs of the skull determine the thickening of the bones of the arch, the increase of the superciliary arches and frontal sinuses, the enlargement of the lower jaw and the external occipital protrusion. Basophilic and mixed adenomas also originate in the anterior pituitary gland. The first of these causes the syndrome, known in endocrinology as the Itzenko-Cushing syndrome (lunar face, obesity, sexual dysfunction, increased blood pressure, systemic osteoporosis).

The assumption of a pituitary tumor is based on clinical and anamnestic data, but an accurate diagnosis is established taking into account the results of radiation studies. The role of the radiologist is very important, since the adenomas of the pituitary gland are subject to surgical or radiation treatment. In the latter case, an impeccable aiming of the radiation beam (for example, a proton beam) is required on the pathological focus to exclude damage to neighboring brain tissues.

The possibilities and methodology of radiation diagnosis depend on the size of the adenoma. Small tumors (microadenomas) on X-rays are not recognized, CT or MRI is required to detect them. On computer tomograms of adenoma, if it is sufficiently well delimited, immersed in the parenchyma of the gland and not too small (not less than 0.2-0.4 cm), it appears as a rounded center of increased density.

Recognition of large adenomas is usually not difficult even when analyzing the survey radiographs of the skull, as they cause changes in the bones forming the Turkish saddle. The saddle increases, the bottom deepens, the walls become thinner, the anterior wedge-shaped processes of the small wings of the sphenoid bone rise. The entrance to the Turkish saddle is expanding. The back is straightened and lengthened.

The size of the Turkish saddle normally depends on the sex, age, and physique of the person, therefore special tables have been created, according to which specialists in the field of radiation diagnostics determine the proper values.

Above we already mentioned craniopharyngiomas - embryonic tumors originating from the remains of the pituitary path (Ratchet's pocket). Craniopharyngioma can grow in the Turkish saddle and then appears typical symptoms of the endosellar tumor, as well as adenomas. However, in the vast majority of cases, it develops above the saddle, quickly leads to visual disorders, increased intracranial pressure and hydrocephalus. Then the entrance to the saddle widens, atrophy and destruction of the apex of the saddle back develop. Diagnosis is facilitated by the detection of a variety of calcareous inclusions, often found in craniopharyngioma, in the form of numerous grains of sand, larger clumps or annular or arcuate shadows.