HOW I DO IT: SIRT for Hepatocellular Carcinoma

Transcription

1 HOW I DO IT: SIRT for Hepatocellular Carcinoma Philip Chong-hei KWOK Department of Radiology and Imaging Queen Elizabeth Hospital HONG KONG SAR, CHINA

2 Declaration I have no financial interest to declare My presentation concentrates on treatment of HCC with SIRT Similar principle for CRC liver metastases Different in patient choice, dosimetry method and dose reduction after previous chemotherapy

3 The Aim of Treatment For beginners and early users, the ultimate aim is To deliver an adequate dose to the tumor(s) accurately and in a safe mode (for both the patients and operators, staff) REMINDER: SIRT is a palliative treatment for most patients!

4 The Challenges Essential to know before and during SIRT Choose the right patient Know the anatomy of supplying arteries, adjacent arteries Know your equipment: microcatheters and embolization material Choose the right dosimetry method

5 Patient selection See the patient in a clinic setting Child Pugh s class A or B (B7 or B8) ECOG score

6 Patient Selection Tumor < 50% total liver volume Patient may still have Child Pugh s A liver function until very late Tumor > 50% liver volume usually cannot receive enough radiation dose for tumor control Has high lung shunting

7 CT Abdomen and CT Angiogram CT abdomen preferrable Tumor size baseline for response assessment later (mrecist) volume measurement dosimetry Portal vein tumor invasion prognostic indicator Extrahepatic spread SIRT exclusion Multiple lung metastases, LNs, bony metastases, etc CT angiogram reconstructed really helpful before catheter angiogram to understand anatomy and supply

8 Catheter Angiogram Use Power injector Fast Frame rate: 7.5 Frames/sec in first 5 to 6 seconds for really clear images, and to avoid respiratory artefacts during subtraction Know the pressure limit and flow rate for microcatheter E.g. 2.9Fr Progreat (Terumo) can accommodate up to 3ml/sec at 750 psi injection pressure

9 Arteries Lots of variants in: hepatic arteries, gastric arteries other adjacent arteries

10 When to Embolize Gastroduodenal Artery Usually embolization is not needed when microcatheter is used, and the catheter tip is deep enough in the target artery for Y90 injection Embolize it when liver is cirrhotic, and with slow antegrade flow in hepatic artery, especially in left and middle HA Embolize it when patient has received previous TACE higher chance of reflux

11 GDA anatomy Anatomy of GDA Early supraduodenal, retroduodenal, superior pancreatico-duodenal branches Embolization till the GDA origin Use the usual principle of embolization one or two stiffer coils (Stainless steel, Platinum, Inconel MReye coils) as scaffolding, then soft coils (Nester) for tight packing

12 GDA anatomy

13 GDA Embolization

14 GDA Reverse blood flow Watch for reverse flow of GDA GDA reverse flow seen in SMA angiogram Flow artefacts noted in coeliac angiogram

15 GDA reverse flow To and fro blood flow in GDA

16 GDA reverse flow Actually, reverse flow of GDA is protective No need to do GDA embolization

17 Right gastric artery Right gastric artery Can arise from LHA, MHA, PHA May form an acute angle with the parent artery, difficult to embolize Embolized with a small and short coil (2-4mm) Retrograde embolization through the left gastric artery

18 Cystic artery Cystic artery No need to embolize most of the time If MAA CT-SPECT shows an intense lightbulb in the gall bladder May embolize with small coils +/- NBCA glue Proximal embolization to prevent ischemic perforation of GB wall

19 Cystic Artery Coned beam CT on site

20 Cystic Artery SPECT-CT after MAA injection shows accumulation in gall bladder

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22 Gastrohepatic trunk Gastrohepatic trunk Left HA and gastric arteries May embolize the main gastric branch

23 Esophageal branch from left hepatic a Left hepatic artery and esophageal branches Gastrohepatic trunk esophageal branches Difficult to embolize the small branches Radiation induced esophagitis

24 Esophageal branches Esophagitis after Y90 Pre Y90 3 months post Y90

25 Esophageal branches Retrospective review of angiogram A small esophageal branch from left hepatic artery, flowing up to the lower thorax

26 Falciform artery From LHA, MHA Supposed to be more common than we observed during TACE/ angiogram 24.5% (Gibo et al)

27 Falciform artery

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31 What is this? See it in angiogram Go back to CT Angiogram May not see the fine vessels Use Coned beam CT to confirm and correlate

32 What if The tumor has parasitic supply from: The inferior phrenic artery The adrenal artery Intercostal artery Internal mammary artery Omental artery Cystic artery

33 Redistribution of blood flow Abdelmaksoud et al. JVIR 2011; 22:

34 Bilbao et al. CVIR 2010; 33: After embolization of LHA from LGA, inject in CHA

35 May not work May cause ischemic complication JVIR 2013

36 Dosimetry Challenges Covered in other talks BSA Model: A simple model Endorsed by SIRTEX Can adjust dose according to the lobar volume to be injected, tumor volume

37 Dosimetry Challenges Partition Model We use Y90 to treat big HCC or with portal vein invasion More logical Similar principle used by researchers for tumor response assessment in glass spheres (whole lobe dosimetry)

38 Challenges of Partition Model Simple if there is one tumor, in one lobe Challenges if Tumor supplied by more than 1 blood vessel how to split the dose Tumor with area of necrosis, or with previous TACE how to decide the dose Tumors of different size in both right and left lobes how much to each HA

39 Partition Model Back to basic of partition model for calculation

40 Planar Views to calculate Percentage of Lung Shunting

41 Planar Views to calculate Percentage of Lung Shunting Lung shunt fraction should be studied as soon as possible after injecting in the target heaptic artery Delay scan: Increased breakdown of MAA in liver higher lung shunt + systemic uptake Wrong dose calculation De Gersem R et al. Clin Nucl Med 2013

42 Axial CT-SPECT with ROIs for MAA distribution in Tumor, right and left lobe Uptake in Right lobe (include tumor) Uptake in left lobe Uptake in Tumor

43 Counts from Planar scan? CT-SPECT? To align the meaning of counts in planar scan and CT-SPECT The equivalent lung count by CT-SPECT= % lung shunt X whole liver count ( 1 - % lung shunt) (Assuming MAA injected in the hepatic arteries is distributed inside the liver and to lungs only, with minimal amount in the rest of body, shortest interval between HA injection and scanning)

44 The Partition Model MIRD principle: 1GBq of Y90 per kilogram of soft tissue results in a delivered dose of 49.67Gy to that tissue Tissue MAA count Proportion [for 1 GBq] Tissue Weight (kg) Gy/ 1 GBq Y90 by MIRD principle [proportion/weight X 49.67] Lung v v/ total count (Vp) 1 Vp x 49.67/1 Tumor in Right lobe Right lobe (excluding tumor) Tumor in Left lobe Left lobe (excluding tumor) w w/total count (Wp) a Wp x 49.67/a x x/total count (Xp) b Xp x 49.67/b y y/total count (Yp) c Yp x 49.67/c z z/total count (Zp) d Zp x 49.67/d

45 The Aim Increase the dose of Y90 till it reaches the tumorcidal dose: 120Gy (at least 100Gy) Without exceeding the safety liver dose Liver with cirrhosis or previous chemotherapy: 40Gy (or 50Gy in suitable patient) Or the safe lung dose Lung : 20Gy (or 25Gy in suitable patient)

46 The Partition Model Can create a simple EXCEL table with input v-z, a-d. Has the lung dose exceeded 20 (25Gy)? Increase Y90 dose till 120Gy Has the liver dose Exceeded 40Gy (50Gy)? w or y = 0 If there is no tumor in that lobe

47 Suggested work-up of activity calculation to minimize REILD while delivering tumoricial radiation This protocol minimizes REILD in HCC patients Importantly, in those with poor liver function, keep D liver to maximum of 40 Gy Gil-Alzugaray et al Hepatology 2013;57:

48 Problem with Partition Model MAA is not an exact surrogate for Y90 microspheres Difference in particles size, number, injection volume Distribution of MAA and Y90 is not uniform in the tumor and non tumor bearing liver Dosimetry is not a precise science yet Need more research and validation

49 On the Day of Treatment Within 3 weeks after MAA study, preferably 2 weeks Catheter and microcatheters in same location Y90 injected according to protocol Femoral wound closure with closure device (Angioseal or Perclose) Radiation safety monitoring by Radiation physicist

50 On the Day of Treatment Patient transferred to Radiation Ward for 1/2 to 2 days according to dose injected (Radiation Law in Hong Kong) Protocols for handling of excreta and blood specimen Medication for pain control Ursodeoxycholic Acid 250mg PO BD for 8 weeks Prednisolone 1mg PO Daily x 4 weeks, then 5mg PO Daily for 4 weeks

51 Follow up Bremsstrahlung scan on next day Planar scan not too helpful because of low resolution, just better than not-to-do Bremsstrahlung CT-SPECT better to pick up GI uptake Register with pre-sirt CT or MR for tumor dose and liver parenchymal dose calculation Post Y90 CT-PET (time of flight CT-PET) Even better resolution and easier to perform Better dose calculation Detect non-target activity and uptake in vascular thrombus

52 Follow up Follow up in out-patient clinic Ultrasound once per month in first 3 months To pick up ascites CT 3 months later for early response assessment +/- MR Diffusion-weighted images (DWI) picks up changes at 1 month: increased ADC

53 More Sophisticated Equipment Angio- CT Suite Much better images as compared with cone-beam CT Much better for calculation of Y90 dose splitting in tumors with 2 or more supplying arteries Much better for imaging of potential Y90 microspheres flowing to extrahepatic locations

54 Intraprocedural CT-PET

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56 I wish I have these, but I don t With a critical mind, carefulness and passion, you can also offer SAFE and EFFECTIVE Y90 treatment to the needed.

57 Thank You