CT scan

• CT colonography
• CT enterography
• CT bronchography
• Cardiac CT scan (calcium score)
• CT coronary angiography

• Head CT scan
• MRI of the pituitary gland
• CT scan of the eye sockets
• CT scan of the craniofacial region
• CT scan of the sinuses
• CT scan of the temporal bones
• CT scan of the craniocervical junction
• Neck CT scan
• CT scan of the cervical spine
• CT scan of the thoracic spine
• CT scan of the lumbar spine
• Chest CT scan
• TK HRCT
• Abdominal CT scan
• CT scan of the abdomen and pelvis
• Multiphase CT scan of the liver
• Multiphase CT scans of the pancreas
• Multiphase CT scan of the adrenal glands
• Multiphase CT scan of the kidneys
• Pelvic CT scan
• MRI of bones and joints
• CT angiography of the cerebral arteries
• CT angiography of the carotid arteries
• CT angiography of the pulmonary arteries
• CT angiography of the abdominal aorta
• CT angiography of the renal arteries
• CT angiography of the iliac arteries
• CT angiography of the limbs

It allows for the assessment of nervous tissue, distinguishing between grey and white matter, the spaces containing cerebrospinal fluid, the ventricular system and the arachnoid cisterns. The examination is carried out without any patient preparation in emergency situations, such as trauma, the differentiation between ischaemic and haemorrhagic strokes, and in the diagnosis of subarachnoid haemorrhages (SAH). Apart from the situations described above, the patient should always have an empty stomach, as a contrast agent must be administered intravenously. With very few exceptions, the contrast agent is administered when neoplastic processes and/or metastases, or inflammation within the brain, meninges or bones, are suspected.

This examination is performed exclusively in patients with contraindications to magnetic resonance imaging (MRI) – which has greater diagnostic value in the assessment of the pituitary gland – and in whom proliferative lesions of the pituitary gland, most commonly adenomas, are suspected. When referring a patient for this examination, it should be borne in mind that, due to the use of thin slices, it is intended solely for the assessment of the pituitary gland, the sella turcica, the cavernous sinuses and the arachnoid cisterns, both parasellar and suprasellar.

One of the advantages of multi-detector CT scanners in this case is the significant reduction in radiation dose, which is particularly important in CT scans of the eye region due to the risk of cataracts. Furthermore, as with CT scans of the temporal bone pyramids, the use of sub-millimetre slices allows for a very detailed analysis of post-traumatic changes throughout the entire facial skeleton. Apart from post-traumatic conditions and the search for a foreign body in the orbit, the scan is performed using a contrast agent (the patient should have an empty stomach). In non-traumatic cases, a CT scan is indicated only if the result of the ultrasound scan routinely performed in such situations is inconclusive. A CT scan enables the assessment of tumour infiltration from the outside, metastases to the eyeball, extraocular structures and primary tumours of the eyeball.

This examination is recommended for assessing the alveolar processes of the maxilla and mandible, and following maxillofacial trauma. The examination is carried out without the use of a contrast agent, unlike in the diagnosis of patients with cancer (primary tumours, metastases and infiltrations from neighbouring organs). During the scan, the patient usually lies on their stomach with their head tilted backwards. The use of multi-detector CT and thin-slice imaging enhances the quality of three-dimensional reconstructions and allows for a more accurate assessment of bone structures, which is particularly important in post-traumatic conditions.

This scan is used to assess congenital abnormalities, post-traumatic conditions and inflammatory conditions. We perform it using high-resolution computed tomography (HRCT), which does not require the administration of contrast agents and involves a low radiation dose for the patient. Patients with suspected primary or secondary sinus tumours are examined using a contrast agent and should therefore attend the scan on an empty stomach. Despite the various methods of data acquisition (patient positioning), the use of multi-detector spiral CT allows for the acquisition of frontal, sagittal and transverse sections using multi-planar reconstruction (MPR).

Thanks to the introduction of spiral CT scanners with the CINE option (multiple scans at the same level), it is now possible to carry out a state-of-the-art assessment of blood flow in the capillaries of the area under examination. This method has been used, amongst other things, to assess cerebral blood flow. It allows the penumbra – an area of ischaemia – to be visualised before irreversible morphological changes, i.e. a stroke, occur there. Conventional CT scans visualise areas of stroke, but do not allow for analysis of the penumbra. CT perfusion is also being introduced for the diagnosis of tumours of the brain, liver, prostate and other organs.

In the diagnosis of organs located within the neck, CT scans of the neck, larynx and nasopharynx are performed. These examinations should be carried out following the intravenous administration of a contrast agent, for which the patient must have fasted. Imaging of the neck is performed to assess lymph nodes, inflammatory and neoplastic infiltrates, and their relationship to arterial and venous vessels, the airways or the salivary glands. The diagnostic accuracy of laryngeal imaging is significantly improved by the use of secondary reconstructions, such as 3D volumetric rendering, MIP, MPR and others, which allow for a better assessment of the shape, size and changes affecting this organ.

This clinically very useful examination has emerged thanks to the introduction of spiral CT, and its quality is improving in line with the evolution of multi-detector technology. Technological advances are making it possible to examine vessels of increasingly smaller diameters. Currently, multi-detector CT scanners allow such large anatomical areas as the arterial vessels of the lower limbs, together with the iliac arteries and the distal abdominal aorta, to be scanned during a single examination. To visualise the blood vessels and the blood circulating within them, we must mix the blood with a contrast agent; and because a large volume of contrast agent is required – usually 2 or more ml/kg of body weight – non-ionic contrast agents are used for the examination, as these reduce the risk of complications. In addition to the routine assessment of cross-sections of the vessels, an important element of the CT angiography assessment is the 2D and 3D reconstructions of the interior of the vessel containing blood mixed with the contrast agent. The examination may involve, amongst other things: cerebral vessels (to detect vascular malformations), the carotid and vertebral arteries (to assess the severity of atherosclerotic changes), abdominal vessels (stenosis of the main arterial trunks, particularly the renal arteries, to investigate the cause of hypertension), the pulmonary arteries (pulmonary artery embolism or embolism of its major branches), the thoracic and/or abdominal aorta (diagnosis of aneurysms).

Computed tomography is one of the fundamental techniques for examining the abdominal cavity. It enables the assessment of parenchymal organs – the liver, spleen, pancreas and kidneys – and, if the ultrasound scan results are inconclusive, it allows the diagnosis to be confirmed and a differential diagnosis to be made between primary and secondary tumours and benign lesions. In addition, we visualise the gallbladder and the extrahepatic and intrahepatic bile ducts. This method also allows us to assess the extent of inflammatory and neoplastic infiltrates within the walls of the stomach, small and large intestines, and adrenal glands, as well as to evaluate local recurrence following tumour resection. Appropriate patient preparation for the examination is always required. This involves filling the intestinal loops with a 1–2% aqueous solution of an iodinated, non-ionic contrast agent, which allows differentiation between the interior of the intestine, its wall and the structures adjacent to the intestines. The patient must fast for 4–6 hours prior to the examination. The volume of fluid administered orally and the duration of administration depend on the indications for the scan. Thanks to multi-detector spiral CT scanners, dynamic multi-phase scans have now become the standard in imaging. A recent development is the use of perfusion scans of the liver and pancreas.

It is performed to distinguish between metastases and vascular malformations of the liver, and in cases of suspected pancreatic cancer; it involves a three-phase scan of these organs.

The possibility of dynamic examinations arose with the introduction of spiral scanners, particularly multi-detector scanners (the scanner must ‘keep up with the passage of the contrast agent through the arterial, capillary and venous beds’).

Indications for a CT scan of the liver:

• Tumour diagnosis: undifferentiated liver lesion, primary liver tumours, metastases.
• Post-operative: complications (haematoma, bile leakage, abscess), perfusion disorders.
• Vascular: portal vein thrombosis, vascular anatomy (pre-operative/intraoperative assessment), Osler’s disease.
• Other: abscess, injuries.
• Quantitative measurements: haemosiderosis (iron content), liver volume and tumour volume.

The examination report should take into account layers thinner than 1 mm (sub-millimetre), a feature available only in multi-detector CT scanners. CT scanning of the temporal bone pyramids is a high-resolution CT (HRCT) scan, performed without the administration of a contrast agent (the patient does not need to fast). It allows for the assessment of the ossicles, the cochlea, the semicircular canals, the internal and external auditory canals, the aeration of the mastoid air cells, congenital anomalies, post-traumatic changes, and benign and malignant proliferative processes. The image quality obtained in two-dimensional and three-dimensional reconstructions is very high, and thanks to the use of spiral, multi-row CT, secondary image processing methods are also available, such as: virtual endoscopy of the inner ear, multi-planar reconstruction (MPR) and virtual reality (VR), which significantly enhance the diagnostic value of the examination.

This examination is recommended in cases of suspected colon polyps, post-inflammatory changes, diverticulosis or cancer; as a screening test; and for all patients in whom a conventional colonoscopy cannot be performed. Conventional colonoscopy is the gold standard for the detection and diagnosis of colon diseases. Before the introduction of virtual colonoscopy into diagnostic imaging, it was only possible to assess the bowel filled with a 1–2 per cent solution of non-ionic, iodinated contrast agents in a conventional CT scan. This allowed for the assessment of wall thickness, changes in the position of the bowel, or changes in the width of its lumen. Virtual colonoscopy allows for the assessment of the inner surface of the bowel walls. This is only possible on suitable workstations – high-performance computers capable of advanced three-dimensional reconstruction. Another prerequisite for obtaining a clear image of the bowel’s interior is the complete emptying of its lumen of food residues; the patient preparation procedure is similar to that for a conventional colonoscopy. However, there is a possibility that, in the near future, we will have access to contrast agents that bind to food contents and allow them to be subtracted from the image.

The most common indications include the assessment of thoracic organs in cases of benign and malignant neoplastic processes, both primary and metastatic, as well as in cases of chronic inflammation or conditions with an atypical course. Other indications include assessing the extent of infiltration in oesophageal cancers, mediastinal lymph node involvement, pulmonary embolism, post-radiation changes, tumour infiltration extending from the pericardium or heart, and chest trauma. To achieve high-contrast visualisation of the heart and large mediastinal vessels, a contrast agent must be administered intravenously. This then makes it possible to distinguish pathological lesions from unaffected organs. For a selective assessment of lung tissue, we perform a chest CT scan with HRCT reconstruction, which is recommended in cases of pneumoconiosis, systemic connective tissue diseases, interstitial pulmonary fibrosis, bronchiectasis and emphysema.

Indications:

• Tumour diagnosis: lung and mediastinal tumours, metastases, tumour assessment (single nodule), assessment of tumour stage.
• Detection and quantification: latent inflammation, tissue breakdown, asbestosis, silicosis, emphysema, bronchiectasis.

High-resolution computed tomography (HRCT) – Diffuse lung diseases:

• Detection of subtle changes in the lung parenchyma.
• Morphological characteristics.
• Quantitative assessment of changes in the lung parenchyma.

A CT scan of the spinal canal is performed solely to assess bony structures in post-traumatic lesions, tumour infiltrates, and degenerative diseases of the small joints of the spine. Another indication is pathology of the intervertebral disc and the adjacent vertebral body surfaces. Patients do not need to fast before this examination. The examination does not routinely require the administration of contrast medium.

CT scans of these organs involve two different examination methods, depending on the indications. The first group of indications includes examinations performed without the use of contrast agents, aimed at assessing bone structure in Paget’s disease, fibrous dysplasia, post-traumatic changes or osteoarthritis of the large joints, where the clinical and radiological picture is inconclusive on a standard X-ray. The second group of indications, in addition to the assessment of bone structures, covers soft-tissue pathologies surrounding the bone, as well as inflammatory and neoplastic infiltrates spreading from bone to soft tissues or vice versa. Indications include benign and malignant tumours of the bones and joints, assessment of the extent of neoplastic infiltrates and their relationship to the bone marrow cavity and soft tissues, as well as chronic and atypical inflammatory conditions of the bones and joints. In these cases, the administration of a contrast agent is necessary – the patient should fast beforehand. Multi-detector CT systems, in addition to enabling a detailed assessment of complex fractures (thin slices, retro-reconstructions and 3D), are also capable of visualising even soft tissues, such as cruciate ligaments, with high quality – for which magnetic resonance imaging is the examination of choice. Furthermore, modern software allows images from different cross-sectional levels of the limb to be superimposed on one another to calculate angles, such as anteversion, or other parameters useful for planning orthopaedic procedures.

This examination is used to assess the bladder in cases of cancer, the pelvic lymph nodes, the extent of tumour infiltration in the reproductive organs, prior to planned surgery or radiotherapy, and to assess recurrence where the ultrasound result is inconclusive. In men, however, a common indication is to assess the extent of prostate cancer and any possible spread to neighbouring organs, where an ultrasound scan is inconclusive. This examination, like an abdominal CT scan, always requires the patient to be prepared for the procedure, except, of course, in cases of trauma. It involves filling the intestinal loops with a 1–2% aqueous solution of an iodinated, non-ionic contrast agent, which allows the interior of the intestine to be distinguished from its wall and the intestine to be separated from neighbouring structures. In addition, the patient must fast for 4–6 hours prior to the examination. The volume of fluid administered orally depends on whether the examination is combined with an abdominal CT scan or performed as a separate procedure. Alternatively, patients undergoing a pelvic CT scan alone may have the contrast agent administered rectally.

When should you consider having a CT scan of the heart:

• Ruling out coronary heart disease in patients at moderate and low risk of developing it.
• In patients where other diagnostic tests (SPECT, exercise test) have not led to a definitive diagnosis, particularly where the patient’s symptoms are atypical.
• Monitoring of patients with risk factors for coronary heart disease (smoking, high blood pressure, obesity, age, high cholesterol). People with diabetes constitute a particular group requiring monitoring, as coronary heart disease may be asymptomatic or present with masked symptoms in this group.
• Inspection of the condition and patency of bypass bridges.
• Assessment for cardiac surgery procedures such as, for example: suspected stenosis of the left main coronary artery, prior to valve replacement, in order to assess the condition of the coronary arteries.
• Prior to the ablation procedure – a thorough assessment of the anatomy of the left atrium, the pulmonary vein ostia and venous drainage, and the exclusion of thrombi in the heart chambers.
• People who refuse to undergo conventional coronary angiography despite there being medical indications for the procedure.
• Suspected coronary artery abnormalities (including in athletes).
• A thorough assessment of cardiac morphology and function in patients with reduced left ventricular ejection fraction (cardiomyopathies) who have contraindications to cardiac MRI.

What are the advantages of a CT scan of the coronary arteries over conventional coronary angiography?

• Low invasiveness – The scan takes 5–10 seconds; it does not require a catheter to be inserted directly into the heart; the contrast agent is administered solely via a venflon inserted into the antecubital vein, as with any other CT scan.
• Assessment of the quality of atherosclerotic plaques that is, their potential stability and the risk of rupture, and consequently the occlusion of the arterial lumen, leading to a heart attack. Coronary angiography provides an image of the arterial lumen but does not allow for an assessment of the arterial walls.
• Description of the anatomy and function of the heart muscle in a manner similar to an ultrasound scan (echo) following each examination; in addition to the assessment of the coronary arteries, this provides further information from the examination.
• Diagnosis of structures adjacent to the heart such as the oesophagus, the spine and the lung parenchyma, which can also cause symptoms similar to those of coronary heart disease.

Contraindications to the test:

• Patients with a recent heart attack and acute coronary syndrome. In these patients, conventional coronary angiography is the recommended investigation.
• Other contraindications are the same as for any other examination involving the administration of an iodine-based contrast medium: symptomatic hyperthyroidism, allergy to iodine, kidney damage, and pregnancy.