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TRIPLE PHASE CT TECHNIQUE for ct scan technicians .pdf
- 2. The AFGHANISTAN RADIOGRAPHERS SOCIETY (ARS) is a non- profit organization, set up by professional societies that represent radiographers in the geographic continent Afghanistan. The role of the ARS is to represent, promote and develop the profession of radiographers in Afghanistan, within the whole range of medical imaging, nuclear medicine and radiotherapy. Over ons
- 3. The Triple phase CT scan of the abdomen is a screening test for carcinoma in the abdominal cavity. Use for early disease detection. This is the most accurate test available for detecting Hepatocellular carcinoma pancreatic cancer as well as problems in the kidneys, spleen, adrenal glands, gall bladder and abdominal lymph nodes. INTRODUCTION
- 4. Largest internal organ and largest gland Lies under diaphragm in the right upper abdomen and mid abdomen and extend into left upper abdomen Shape- wedge , base to right, apex to left Extension- from 5th ICS the Rt MCL down to costal margin Measurement-12-15cms coronally and 15-20 cms transversely Weight- 1800gms in males, 1400gms in females INTRODUCTION TO LIVER
- 6. LOBES OF LIVER Liver is divided into right and left lobes by falciform ligament. The right lobe also has two miner lobes Caudate lobe Quadrate lobe
- 20. RADIOLOGICAL ANATOMY OF LIVER IN CT
- 25. Pre-contrast deferred in follow up/ metastasis Arterial phase of contrast enhancement Portal phase of contrast enhancement Venous phase equilibrium Abdominal CT completed to iliac crest level haemangioma suspected-additional delayed images to assess for filling of haemangioma TECHNIQUE
- 26. Non-ionic contrast Serum creatinine EGFR-estimated glomerular filtration rate Contrast dose- 1.5 r 2 ml/kg max 150 ml Rate of injection- 4 ml/sec at 300psi Iv cannula-18 -20 Gage Multislice CT- reduce contrast dose REQUIRMENTS
- 27. Consent: Empty stomach -fasting for 6 hrs. Previous intravenous contrast injections? Any side effects or reaction due to contrast media? Diabetic? Renal abnormalities? Periods allergies? Thyroid abnormalities? Pregnancy or breast feeding? Any medication using? Dialysis?
- 28. PROTOCOL MODE SPIRAL SLICES Non contrast -5mm arterial phase -5mm venous phase-3mm delayed phase -3mm FEED-5mm PITCH-0.7mm RECONSTRUCTION-3mm SCAN ORIENTATION-Non contrast-craniocaudal Arterial craniocaudal Venous caudocranial Delay-caudocranial
- 29. PROTOCOL TIMING OF SCAN---ARTERIAL bolus tracking 18 -25 sec PORTAL -45 sec VENOUS -65 sec DELAY-5 MIN COLLIMATION-- spatial resolution /image noise TABLE SPEED --- 15 MM/rotation Kvp/mAs ---120/225 FOV ----- 350mm FILTERS-B30S MEDIUM SMOOOTH High quality , large volume, reasonable radiation dose to obtain 3D multiplanar images in single breath hold
- 30. ARTERIAL PHASE scan during injection : arterial phase ,highlight the lesions in or around the artery leading into the liver Arterial phase of scanning method- performed approximately 30 secs after the contrast injection is initiated and is most accurately determined by using bolus tracking software (eg Smart prep) to monitor the level of contrast enhancement in the aorta and automatically triggering the scan when it reaches a predetermined level of enhancement (eg 120 HU) 5mm-post contrast-top to bottom of liver for arterial phase ,2.5mm recon Excellent hepatic arterial opacification with minimally contrast in portal vein.
- 31. Hypervascular lesions like HCC, Focal nodular hyperplasia, Adenoma, haemangioma enhance during the arterial phase and appear hyperdense Arterial phase images are also used for pre operative evaluation of arterial vasculature through the use of MIPs and 3D reconstructions
- 32. Early arterial phase: 15-20 sec or immediately after bolus Late arterial phase: 35-40 sec or 20 sec after bolus Demarcation of vessels enhancement of hypervascular- elisions, stomach Normal parenchyma is supplied for 80% by portal vein and only for 20 % by hepatic artery Normal parenchyma will enhance maximally in the hepatic venous phase at 65-75 sec and only a little bit in the late arterial phase 18-35 secs
- 34. Scan during injection or shortly after : portal venous phase, show lesions in or around the portal vein Portal venous phase performed 70-90 secs post contrast and hypovascular lesions appear hypodense and hypervascular lesions appears isodense (same density as surrounding liver) SCAN METHOD- 5mm with 2.5 mm recon 80 sec delay , scan the entire abdomen in this acquisition (top of liver to spleen) Hypovascular lesions like- metastasis , cysts and abscesses Hypovascular mets- colon PORTAL VENOUS PHASE
- 36. Delayed scan after injection : allow soft tissue to absorb contrast and highlights changes in tissues Delayed scan through kidney at 3mins Delayed phase performed 5-10 mins post contrast and used to characterise the lesions hemangiomas slow to enhance and some HCC appear hypodense due to washout SCAN METHOD- 5mm with 2.5 recon 3mins from injection (top of liver to bottom of kidneys) DELAYED PHASE
- 37. ENHANCEMENT OF- fibrotic lesions, still enhancement of kidney and urinary collecting system DETECTION OF liver cholangiocarcinoma, fibrotic mets, kidney- TCC