How to do a CT guided renal cryoablation

as performed by AM and JF

 

Review prior imaging

 

Lesion in question was enhancing mass anterior R kidney cortex interpolar to lower pole region

 

Ideally have anesthesia present to sedate the patient

Decide on supine or prone access

Decide on decubitus positioning to make procedure easiest

 

Do initial scan and measure out to lesion from skin so know the probes will make it to the lesion

Also decide how many probes will allow for adequate coverage

Place straws

Scan again with straws and choose entry point

In this case, 2 probes were placed from inferior to superior aspect of the lesion

Have the preprocedure scan out so can compare contrast enhanced ct to noncon CT as can be tricky to see lesion on noncontrast CT with different positioning

Prep and drape area, numb skin and subcu wit lido, make skin nick

Start advancing the probe under intermittent CT guidance

Make subtle adjustments in probe position

Make sure can view CT images in the CT suite with a connected monitor to assist with needle placement at the scannerside, sometimes this is not avail

Note that the needle tip should advance just beyond the lesion as the ablation zone is usually centered a few cm prox of the needle tip

When viewing images at the CT tech area, be aware of cranial aspect, caudal aspect, needle tip position, and have tech measure distance to lesion so know how far to advance once at the scannerside

Once you are at the lesion and all the probes are placed, can perform the biopsy

Reason being that bleeding from the biopsy can be stopped by performing the ablation

Make sure you have introducer and 18 gauge biopince of sufficient length to access the lesion

Can use your probes as guides

Keep in mind can be confusing to sort out which needles are the probes and which are being advanced

Perform biopsy and remove biopsy instruments

Then can perform ablation

Have rep nearby for questions

Goal is 2 freeze and 2 thaw cycles

Can use active thaw or just regular thaw

AM Cycle:  10 min freeze, 8 min passive thaw, 10 min freeze, active thaw

Check ice ball appearance on intermittent CT and eval margins.  The ice ball will be hypodense

After last thaw cycle, ensure temperature within ablated tissue is 23 deg C prior to removal of probes to avoid kidney fracture (apparently)

Check post procedural imaging to exclude perirenal hematoma or active bleeding

Pt. can be admitted overnight

Once probes removed, placed sterile dressing and terminate procedure

 

Probes used:

Percryo PCS-17

​

​

​

Tips for CT and US guided microwave ablation of Liver

did one w/ JR around 4/2018

​

superficial L hepatic lesion

used CT and US

could see lesion well on US

lesion was close to stomach and pancreas

used 21G needle under US guidance for hydrodissection

used almost 1 L of D5W for hydrodissection

could have placed wire and then placed angioplasty balloons if wanted to

after aggressive hydrodissection, got a good placement of the needle using constant US guidance

did mild-mod burn at 60W

got great appearance of coverage, definite no involvement of critical structures such as stomach or panc

learned the hang of microwave ablation 

bottom line - its not F'ing rocket science

​