Abdominal CT Scan

Liver

No. Name of student1 الزيدي عبدالرحمن

2 المحمود عبدالعزيز

3 الغ�فيص عبدالله

4 الوليعي عبدالله

5 المدلله عبدالمحسن

Content :

1-INTRODUCTION 2- ANATOMY OF LIVER 3-INDUCATION 4-CONTRAINDUCTION 5-PATIENT PREPARATION6-CONTRAST MEDIA7-TECHNIQUE 8-CT IMAGES

1.what is the definition of CT scan?COMPUTED TOMOGRAPHY DEFINED:Computed tomography uses a computer to process information collected from the passage of x-ray beams through an area of anatomy. The images created are cross-sectional.difference between radiography and tomography:A. Radiography :_The use of X-rays to view a non-uniformly composed material such as the human body.B. Tomography : _Imaging by sections or sectioning.

2. what are the main advantage of CT over conventional radiography?

1. Ability to differentiate small differences in density of anatomic structures and abnormalities.2. Superior quality of the images.3. Better detail compared with ultrasonography.4. Relatively quick compared with MRI scanning.5. Most systems can be scanned (brain to leg).

Benefits of CT include more effective medical management by:

1. determining when surgeries are necessary2. reducing the need for exploratory surgeries3. improving cancer diagnosis and treatment4. reducing the length of hospitalizations5. guiding treatment of common conditions such as injury, cardiac disease and stroke6. improving patient placement into appropriate areas of care, such as intensive care units

3. what are the instrument we use in CT scan?

There are essentially two types of CT scans:

A. Conventional CT scan - the scan is taken slice by slice and after each slice the scan stops and moves down to the next slice - e.g. from the top of the abdomen down to the pelvis. This requires patients to hold their breath to avoid movement artefact.

B. Spiral/helical CT scan - this is a continuous scan which is taken in a spiral fashion. It is a much quicker process and the scanned images are contiguous.

4. what are the anatomy of liver in the CT scan?

The anatomy of the liver can be described using two different aspects: morphological anatomy and functional anatomy. The traditional morphological anatomy is based on the external appearance of the liver and does not show the internal features of vessels and biliary ducts branching, which are of obvious importance in hepatic surgery.

Segmental anatomy

Segment 1 : posterior segment – caudate lobe

Segment 2 : left posterior lateral segment

Segment 3 : left anterior lateral segment

Segment 4 : left medial segment

Segment 5 : anterior medial segment

Segment 6 : anterior lateral segment

Segment 7 : posterior lateral segment

Segment 8 : posterior medial segment

5. what are anatomic positions of view liver in the CT scan?

Axial view - Coronal view - Sagittal view

Indication of liver study in CT A- Diffuse liver diseases:

1- steatosis (Fatty Liver): its the abnormal accumulation of lipids, particularly triglycerides within hepatocytes due to: alcohol abuse, diabetes mellitus, and obesity.

2- cirrhosis: its chronic liver disease processes which cause hepatocellular necrosis and often due to: alcohol: 60-70%

viral hepatitis: 10% 3- hepatitis : is an inflammation of the liver. 4- Sarcoidosis: is a systemic inflammatory disease of unknown

origin characterized by the formation of non-caseating granulomas. 5-portalvenous thrombus.

B- Focal liver lesion:

1- benign tumors like:A- cysts (simple and polycystic)B- Hemangioma: is a noncancerous (benign) mass that occurs in the liver.C- focal nodular hyperplasia. is a benign tumor of the liver (hepatic tumor), which is the second most prevalent tumor of the liverD- hepatocellular adenoma: is an uncommon benign liver tumour that is hormone induced. The tumours are usually solitary and have a predilection to haemorrhage

2- Malignant tumors: A- hepatocellular carcinoma: it’s a cancer that

bring in liver.

B- cholangiocarcinoma: are malignancies of the biliary duct system that may originate in the liver and extrahepatic bile ducts, which terminate at the ampulla of Vater

C- metastasis: is a cancerous tumor that has spread to the liver from another place in the body. It is also called secondary liver cancer

Contraindication First: Related to contrast agent: A- oral contrast: gastrografin or barium sulfate Hypersensitivity: history of asthma, premedication with

antihistamines

Thyroid Dysfunction: known or suspected hyperthyroidism or goitre, as iodinated contrast media may interfere with thyroid function.

Very Poor State of Health: careful consideration in patientswith a very poor general state of health.

Gastrointestinal: In case of prolonged retention of Gastrografin in the gastrointestinal tract (e.g.obstruction, stasis), tissue damage, bleeding, bowel necrosis and intestinal perforation may occur.

Hydration: Adequate hydration and electrolyte balance should be established and maintained in the patients, since the hyperosmolarity of Gastrografin may cause dehydration and electrolyte imbalance.

Second related to I.V. Contras contraindication:There are two main contraindications for the administration of iodinated IV contrast: contrast induced nephropathy and allergy to iodinated contrast. Current policy suggests a creatinine of less than or equal to 1.5 mg/dl and no evidence of acute kidney injury for IV contrast administration. Hepatic failure. Death brain. Any allergic reaction. Hemorrhage. Vascular rupture.

Preparation the patient for liver scan The patient fasting for few hours before the scan. All metallic objects should be removed from the

area to be studied, including such items as earrings, bobby pins and necklaces.

The patient may want to wear loose, comfortable clothing because he\she will be required to lie down on the table.

The patient should be instructed to empty the bladder before the is done, because use of iv contrast may causes the bladder to fill rapidly ,and the scan should not be interrupted for a bathroom break.

Contrast media

- Contrast material used in the liver is Iodine-based contrast materials ,injected into a vein (intravenously) used to enhance x-ray and CT images.

- The injection should therefore ideally have a rapid flow of2-6 ml/sec for achieving sufficient density enhancement.

- Avenflon canula with a diameter of at least (20G)for children, or preferably (18G-17G)for adults, is used.

Performing the procedureThe technologist begins by positioning on the CT examination table, scouts AP and lateral head or feet first. Arms flexed under the head. Straps and pillows may be used to help you maintain the correct position and to help you remain still during the exam.

The techniqueYou may be asked to take inspiration during the scanning. Any motion, or body movements, can lead to artifacts on the images. Abdomen is performed with 5 mm slice thickness. Pre and post contras medium. Start post C.M after 10 secStart location: at the level of xiphisternumEnd location: Just at the level of iliac crest Liver study extend from above the xiphoid, and extend quite far caudally to the reference point at umbilical region.The tri-phases important from up to down arteries, from down to up portal veinAnd from up to down veins

The tri-phases

cont

Next, the table will move quickly through the scanner to determine the correct starting position for the scans.

For spiral scanning volume acquisition 10mm slice thickness, and 10 mm table incremented but with 5 mm reconstruction index to give over-lapping section.

The CT examination is usually completed within a few minutes.

Normal liver CT

Steatosis (Fatty Liver):

A CT scan of the upper abdomen showing disproportional steatosis(fattening) of the liver.

Hepatitis

antigen-positive chronic hepatitis B.

Cystic (simple)

Hepatic hemangiomas

Malignant tumors

Hepatocellular carcinoma

Metastases

 Multiple hypoattenuating lesions of varying sizes are seen in both the left and right lobes of the liver, some

with indistinct margins. The patient had colorectal carcinoma.

Conclusion For treatment planning we use

Ultrasound first before other modality because:

1- US more safer 2- low cost. 3- less preparation. Benift for CT: 1- Has Tri-phase technique that can

localize the hepatic paranchyma and vascular supply.

2- has more sections than US. 3- enhance the supply for tumor.

MRI: 1- better for soft tissue. 2- safe than CT 3- long time than CT. 4- worst for bone.

References

PROTOCOLS FOR MULTISLICE CT second edition, Burening. A.kuettner and the flohr editors

Computed tomography for technologists, lois E. romans. http://radiopaedia.org Lectuer notes http://www.epidemic.org

Thank you