cttg leg runoff

Scott PlowmanCT SupervisorSymbion ImagingKnox Private Hospital : 

CT Leg Runoff Scott PlowmanCT SupervisorSymbion ImagingKnox Private Hospital

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Peripheral arterial disease (PAD) A chronic and progressive disease The manifestation of atherosclerosis in the arteries usually of the lower limbs 1.6-12% of people over 55 y.o. Usually presents as intermittent claudication Smokers, diabetics, hyperlipidaemia Exact visualisation of extent and severity of disease is mandatory prior to treatment.

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Duplex Ultrasound (US), MRA, CT, and DSA Need to be sure that you can make an accountable therapeutic choice with the diagnostic information available

MRI : 

MRI No radiation Patient compliance/contraindications Very motion sensitive Limited resolution when scanning large area Sensitivities 77-95%, specificities 84-95% Time consuming Toxic effects of gadolinium Nephrogenic systemic fibrosis Now there is Gadovist – no reported cases of NSF macrocyclic

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Duplex Ultrasound : 

Duplex Ultrasound Non-invasive Low cost No radiation Arduous task No roadmap Slow blood flow makes it very difficult to get readings Difficult/impossible in presence of calcified blood vessels Difficult with fat/swollen/oedematous legs Bowel gas for pelvic vessels Ulcers

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DSA : 

DSA Gold standard Temporal/haemodynamic information Possible intervention at the time Patient discomfort High radiation dose for both patient and investigator Invasive Risk of complications : 1% Expensive Port-procedural observation

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CT : 

CT CT image quality of all arterial segments must be sufficient for diagnosis Older scanners had difficulty with smaller vessels 16 / 64 slice = faster, better resolution, increased tube capacity Non-invasive, outpatient procedure Inexpensive Fast (~15min)

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Numerous papers showing CT is accurate sometimes even better than DSA (Schernthaner et al. 2007) Accurate with grafts No studies done with 64slice technology Accurate- Willman et al. 16slice scanner, 0.75mm thickness Aortoiliac – 95% sensitivity, 98% specificity Femoral – 98% sensitivity, 94% specificity Poplitealcrural – 96% sensitivity, 95% specificity

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Disadvantages Contrast contraindications Acceptance by vascular surgeons Post processing can be time consuming May be limited in heavily calcified arteries Radiation dose

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Radiation dose Increase the number of detector rows, improve beam efficiency Improved dose modulation with all vendors Less than with DSA Willmann et al. 2003 CT: 6.92mSv for men, 5.43mSv for women DSA: 11.1mSv for men, 14.1mSv for women Willmann et al. 2005 CT: 3.0mSv for men, 2.3mSv for women DSA : 11mSv

The Knox Way : 

The Knox Way 2 long Scouts Legs together with tourniquet/strap 17/01/2009 19

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2 timing boluses 15ml contrast, 15ml saline for each 4-4.5ml/sec One at level of approximately coeliac axis Other just below the knee for the distal popliteal arteries Perform Multi-image ROI (MIROI) on each of these

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70-90ml 370mg/ml Isovue @ 4-4.5ml/sec Total 100-120ml contrast 50ml saline @ 4-4.5ml/sec Total 80ml saline Dual barrel injector Possible pitfalls- Heavily calcified arteries – widen the window width Incorrect timing of contrast

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Post Processing Axials the entire way Sagittal MIPs done in 3 sections- 1 abdo/iliac, 1 femur, 1 popliteal-crural Ensure overlap Coronal MIPs done in 3 sections VR entire length and then filmed in same 3 sections 3D MIP of entire section and also in 3 magged areas Curves along all vessels, including abdominal vessels, and all 3 from trifurcation at knee- curves most important images.

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17/01/2009 43 SEED

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Summary: Long Scouts 2 timing boluses Calculate timing carefully Inject contrast quickly Ensure patient compliance- explain entire process to them Reconstruct as required, minimum is axials, coronal +/or Sagittal mips and curves

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CONCLUSION Explain everything to patient Timing is essential Reconstruct curves